Thermoluminescence characteristics of the 375 degreesC electron trap in quartz.
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Journal Article↗
Biomedical subjects
A Franklin
Publications and source records attributed to A Franklin.
Spread of a newly found trimethoprim resistance gene, dhfrIX, among porcine isolates and human pathogens.
A plasmid-borne gene mediating trimethoprim resistance, dhfrIX, newly found among porcine strains of Escherichia coli, was observed at a frequency of 11% among trimethoprim-resistant veterinary isolates. This rather high frequency of dhfrIX could be due to the extensive use of trimethoprim in veterinary practice in Sweden. After searching several hundred clinical isolates, one human E. coli strain was also found to harbor the dhfrIX gene. Thus, the dhfrIX gene seems to have spread from porcine bacteria to human pathogens. Furthermore, the occurrence of other genes coding for resistant dihydrofolate reductase enzymes (dhfrI, dhfrII, dhfrV, dhfrVII, and dhfrVIII) among the porcine isolates was investigated. In addition, association of dhfr genes with the integraselike open reading frames of transposons Tn7 and Tn21 was studied. In colony hybridization experiments, both dhfrI and dhfrII were found associated with these integrase genes. The most common combination was dhfrI and int-Tn7, indicating a high prevalence of Tn7.
Animals↗
Mechanical assistance of the left ventricle: acute effect on cardiac performance and coronary flow of different perfusion patterns.
Mechanical circulatory assistance by ventricular assist devices provides an opportunity to influence the aortic pressure pattern, which may affect ventricular loading and coronary perfusion. The effect of synchronous, pulsatile coronary perfusion of an assist device-supported left ventricle has not been studied. To analyze the effect of different perfusion patterns on left ventricular performance and on coronary flow, independent of pressure and volume loading, we used three different modes of aortic perfusion in an isometric, contracting, isolated canine heart model. The effect of nonpulsatile, counter-pulsatile, and copulsatile coronary perfusion was analyzed in four subgroups to simulate different, clinically relevant situations (using two different ventricular end-diastolic volumes [normal and high] and two mean perfusion pressures [normal and critically low]). Our experiments demonstrated that total coronary flow is optimized by making the perfusion pressure pulsatile and by synchronously timing the pump systole with ventricular diastole (counterpulsation). Under identical conditions of preload and mean perfusion pressure, coronary flow and left ventricular contractility were decreased during non-pulsatile and copulsatile aortic perfusion when compared with counterpulsatile flow. There were no significant differences between the nonpulsatile and copulsatile modes. We conclude from these data that a nonejecting, but contracting, left ventricle will have improved systolic function and coronary blood flow if the coronary perfusion pressure is synchronized in a counterpulsatile manner. This is a significant implication for mechanical left ventricular assist devices when used to promote myocardial recovery.
Animals↗
Excitation-contraction uncoupling during ischemia in the blood perfused dog heart.
The bioluminescent of Ca(2+)-indicator, aequorin, was loaded into the left ventricular apex of blood-perfused hearts from 13 dogs for simultaneous recording of left ventricular pressure and intracellular calcium levels. During a 2 minute period of ischemia, systolic and diastolic pressures significantly decreased. In contrast, these pressure changes were associated with an increase in both systolic and diastolic calcium reaching a maximum diastolic value of 0.59 microM and a systolic value of 1.11 microM. This apparent dissociation between pressure and [Ca2+]i supports the hypothesis that changes in myofilament Ca2+ responsiveness are of major importance in modulating contractility during ischemia in large mammalian hearts.
Aequorin↗
Distribution of penicillin-G and spiramycin to tissue cages and subcutaneous tissue fluid in calves.
Antibacterial drug concentrations in serum, tissue cage fluid (TCF) and subcutaneous tissue fluid (SF), sampled either by filter paper discs or by microcapillaries, were measured after single intramuscular injections of potassium penicillin-G (KPG), procaine penicillin-G (PPG) and spiramycin adipate in calves. Concentration-time curves had essentially similar profiles in serum and SF, but peak levels were lower and occurred later in SF. From approximately four hours after drug administration, penicillin-G levels in SF were similar to levels in serum after KPG as well as after PPG administration. Elimination half-life (t1/2) of penicillin-G in serum was similar to t1/2 in SF after PPG administration but was longer in SF than in serum after KPG administration. Spiramycin concentrations were higher in SF than in serum and the t1/2 of spiramycin in SF was longer than in serum. For all three drugs, the t1/2 was longer in TCF than in serum and concentration-time curves in TCF were characterised by a slow rise and decline. The two methods of sampling SF, by filter paper discs and by microcapillaries, gave similar but not identical results. Penetration into SF and TCF, measured as the total area under curve ratio, was better for spiramycin than for penicillin-G, but the latter drug had a higher penetration ratio to TCF in the first 12 hours.
Animals↗
Multiple regulatory elements determine adrenocortical expression of steroid 21-hydroxylase.
Steroid 21-hydroxylase (21-OHase) is specifically expressed at high levels in the adrenal cortex, where it is required for the synthesis of mineralocorticoids and glucocorticoids. In this study, we have investigated the regulatory elements in the 21-OHase promoter region which contribute to the expression of this gene in Y1 adrenocortical cells. Eight potential regulatory elements in the 5'-flanking region of the 21-OHase gene were identified by DNase I footprinting and gel mobility shift experiments. Some of these footprints were produced by nuclear extracts from many cell lines, whereas other interactions were seen only when using nuclear extracts from Y1 adrenocortical and MA-10 Leydig tumor cells. Mutation of most of the elements markedly decreased the expression of a 21-OHase gene transfected into Y1 cells, thus documenting their functional importance for expression. Moreover, oligonucleotides containing the sequences of two related elements at -65 and -210, which share the heptamer AGGTCAG, increased the activity of a heterologous promoter in a Y1 cell-specific manner. Collectively, these results demonstrate that expression of 21-OHase in Y1 adrenocortical cells requires interactions among multiple cis-acting elements and regulatory proteins.
Adrenal Cortex↗
Plasmid profile analysis and restriction enzyme fingerprinting of Salmonella DO-group strains.
In Sweden Salmonella dublin is the most common serotype within the DO-group isolated from animals. In recent years also salmonella strains belonging to the DO-group but lacking H-antigen have been isolated from cattle in different areas. It was not possible to further differentiate the latter strains by serological methods. However, all Salmonella dublin strains and those strains lacking H-antigen carried a 50 Mdal plasmid exhibiting the same EcoRI and Hind III restriction enzyme digestion pattern. Two of the 26 strains contained an additional 5 Mdal plasmid. Other serotypes within the DO-group investigated, namely Salmonella enteritidis and Salmonella panama, carried plasmids smaller than 50 Mdal. The plasmid profiles and restriction enzyme digestion patterns indicated that the salmonella strains lacking H-antigen were variants of Salmonella dublin. Thus, analysis of plasmid profile and restriction enzyme fingerprinting are useful complements to serological methods in the differentiation of salmonella DO-group strains.
Drug Resistance, Microbial↗
Identification and characterization of two upstream elements that regulate adrenocortical expression of steroid 11 beta-hydroxylase.
We have studied the mechanisms that regulate the expression of the mouse gene encoding steroid 11 beta-hydroxylase (11 beta-OHase), a steroidogenic cytochrome P450 enzyme that is expressed only in the adrenal cortex. DNase I footprinting and gel-mobility shift analyses revealed potential regulatory elements at -370 and -310 in the 11 beta-OHase promoter region. To determine the contributions of these elements to expression, we altered their sequences by site-selected mutagenesis and studied promoter activity after transfection into Y1 mouse adrenocortical tumor cells. Mutation of either element markedly decreased basal promoter activity but did not affect the response to treatment with 8-bromo cAMP. These experiments thus document the functional roles of these elements, within the context of the intact promoter, in constitutive expression of 11 beta-OHase. Moreover, addition of either of these elements to p-40GH, a 5'-deletion plasmid containing 11 beta-OHase sequences from -40 to +8 upstream of a growth hormone reporter gene, significantly increased promoter activity but did not confer cAMP responsiveness. Finally, increased expression was seen after transfection of Y1 derivatives deficient in cAMP-dependent protein kinase, indicating that neither element required cAMP-dependent protein kinase activity. These studies thus define two regulatory elements that play important roles in 11 beta-OHase expression.
Adrenal Cortex Neoplasms↗
A cAMP-responsive element regulates expression of the mouse steroid 11 beta-hydroxylase gene.
In Y1 mouse adrenocortical tumor cells, expression of steroid 11 beta-hydroxylase (11 beta-OHase) is stimulated by cAMP following a delay of 4-6 h. Our results demonstrate that a cAMP-responsive element (CRE) within the 11 beta-OHase promoter region is a major determinant of this induction. The 5'-flanking sequences from the mouse 11 beta-OHase gene were placed in front of a human growth hormone reporter gene and transfected into Y1 cells. Treatment of transfected cells with 8-bromo-cAMP increased expression directed by the 11 beta-OHase 5'-flanking region by 3.8-fold. In 5'-deletion analyses, 123 base pairs of 5'-flanking sequences were sufficient for cAMP induction, whereas cAMP treatment did not affect expression of a plasmid with only 40 base pairs of 5'-flanking sequence. Within these 123 base pairs, a region from -56 to -49 matched 7 of 8 bases comprising the consensus sequence for the CRE. 11 beta-OHase 5'-flanking sequences from -65 to -42, including the CRE-like sequence, conferred cAMP inducibility to promoters from the thymidine kinase and chorionic gonadotropin alpha-subunit genes. DNase I footprinting and Southwestern blotting analyses demonstrated that the protein which interacted with the CRE in the 11 beta-OHase promoter region was similar to the CRE-binding protein associated with other cAMP-regulated genes. Together, these results suggest that an interaction between the 11 beta-OHase CRE and CRE-binding protein mediates cAMP induction of the 11 beta-OHase gene.
Adrenal Cortex Neoplasms↗
Concentrations of sulphadimidine, oxytetracycline and penicillin G in serum, synovial fluid and tissue cage fluid after parenteral administration to calves.
Drug concentrations in serum, synovial fluid and tissue cage fluid (TCF) in calves were measured after single i.m. doses of oxytetracycline hydrochloride (OTC), procaine penicillin G (PPG) and potassium penicillin G (KPG) and single i.v. doses of sulphadimidine (SDM) and OTC. For all drugs, concentration-time curves in serum and synovial fluid were not identical but they had similar profiles, with peak levels occurring at about the same time. Concurrent concentrations were lower in synovial fluid than in serum. For each drug, elimination half-lives from synovial fluid and from serum were similar, except for penicillin G after KPG administration which had a significantly longer half-life from synovial fluid than from serum (P less than 0.05). Of the two penicillin G preparations, PPG gave a significantly higher synovial fluid:serum area under curve (AUC) ratio than did KPG; 0.76 +/- 0.10 and 0.54 +/- 0.12, respectively (P less than 0.05). For OTC, the synovial fluid:serum AUC-ratio was 0.33 +/- 0.12 after i.m. and 0.34 +/- 0.08 after i.v. administration. Drug concentration-time curves of TCF had different profiles compared with serum, with relatively low and delayed peak levels and slow elimination from TCF. TCF:serum AUC-ratios did not differ significantly for i.m. and i.v. administration of OTC; 0.10 +/- 0.10 and 0.19 +/- 0.03 respectively (P greater than 0.05). Potassium penicillin G (KPG), however, gave a significantly higher TCF:serum AUC-ratio than PPG; 0.55 +/- 0.21 and 0.19 +/- 0.07, respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Augmented bacterial adherence to tracheal epithelial cells is associated with gram-negative pneumonia in an intensive care unit population.
Gram-negative pneumonia is a frequent complication of intubated patients in an intensive care unit (ICU), and the adherence of the bacterial pathogen to the respiratory epithelial surface is thought to be the critical initial step in the infection process. However, the correlation between bacterial adherence to tracheal epithelial cells (TEC) and the acquisition of pneumonia and whether intubation or its duration affects bacterial adherence to TEC is unknown. To examine these factors we initially established that the normal adhesion index range for Pseudomonas aeruginosa strain 492c adherence to TEC was zero to 18.83 cfu/TEC on the basis of the adhesion indices of 12 healthy volunteers and 20 surgical patients undergoing elective bronchoscopy. Forty-two analyses of the adhesion index for P. aeruginosa binding to TEC of 24 ICU patients were performed in this study. Analysis of the data indicated that the adhesion index was not correlated with intubation or the duration of intubation. However, an elevated bacterial adhesion index was significantly (p less than 0.001) correlated with pneumonitis. Pneumonitis was observed in 11 of the 12 patients who had an elevated or augmented bacterial adhesion index, whereas pneumonitis was observed in only one of 12 patients who had a normal adhesion index. The bacterial adhesion index was found to parallel the clinical situation in five patients where three patients developed high adhesion indices and acquired pneumonitis and two patients who initially had pneumonitis and elevated adhesion indices subsequently resolved their pneumonitis, and their adhesion indices fell to within the normal range.
Adult↗
Cytotoxin activity on Vero cells among Escherichia coli strains associated with diarrhea in cats.
The role of Escherichia coli as a causative agent of diarrhea in cats was investigated. Isolates of E coli from healthy and diarrheic cats were serotyped and investigated for their biochemical characters, production of cytotoxin activity on Vero cells, heat-labile enterotoxin, heat-stable enterotoxin, and hemagglutination of erythrocytes from other animal species. None of 48 investigated strains produced heat-labile enterotoxin or heat-stable enterotoxin, nor did they agglutinate erythrocytes. Most strains were hemolytic and belonged to O-serotypes 2 and 6. Cytotoxin activity on Vero cells was significantly more common and produced in greater amounts among E coli strains isolated from diarrheic cats, and was neutralized by anti-Shiga-like toxin I serum.
Animals↗
Comparison of washed blood and oxygenator whole blood as vehicles for sanguinous multidose cardioplegia.
The effects of washed blood or oxygenator-traumatized whole blood as vehicles for sanguinous cardioplegia were studied utilizing the isolated blood-perfused dog heart preparation. Hearts were subjected to 2 hr of potassium-induced arrest at 27 degrees C followed by 90 min of normothermic reperfusion. Washed blood cardioplegia (n = 7) contained blood washed thrice with saline while oxygenator blood cardioplegia (n = 6) contained whole blood which had been exposed to an extracorporeal circuit for 30 to 45 min. Cardioplegic solutions were administered at a perfusion pressure of 100 mm Hg every 15 min during arrest. While the arrest-reperfusion sequence caused minor variations in the mechanical, metabolic, and biochemical parameters tested, generally insignificant differences were found to exist between groups. Differences in coronary washout PCO2 appeared to be due to inherent differences between the two cardioplegic solutions. Thus, while washing blood may be thought to be beneficial and whole blood from the extracorporeal circuit may be theorized to have a deleterious effect on the myocardium, excellent recovery of mechanical function was observed with both cardioplegic solutions. The present study suggests that it is unnecessary to wash the sanguinous cardioplegic solution obtained from the cardiopulmonary circuit.
Adenosine Triphosphate↗
Unusual causes of calf swelling--1. Unusual presentation of a tibial artery false aneurysm.
Peripheral aneurysms of the leg are rare, and nearly always involve the popliteal artery. We describe the unusual presentation of a swollen leg caused by a large false aneurysm of a branch of the posterior tibial artery. This developed in the absence of either a history of trauma, local infection or infective endocarditis.
Aneurysm↗
Concentrations of penicillin, streptomycin, and spiramycin in bovine udder tissue liquids.
Concentrations of benzylpenicillin and spiramycin adipate were determined in bovine plasma and milk and in lymph draining the udder tissue after IM or IV administration. Combined benzylpenicillin and dihydrostreptomycin sulfate concentrations were also determined in the same fluids after intramammary injection. A superficial parenchymal lymph vessel, afferent to the supramammary lymph gland of the left quarters, was cannulated with a polythene catheter from which the lymph was allowed to drain freely. After injections of 9.5 mg of benzylpenicillin/kg of body weight IM, a mean peak concentration (PC) in lymph (3.7 micrograms/ml), constituting 77% of the PC in plasma (4.8 micrograms/ml), was obtained 0.5 to 1 hour after PC in the plasma. The benzylpenicillin lymph concentration was close to that in plasma for about 7 hours after injection. Thereafter, the benzylpenicillin lymph concentration continued to exceed that in plasma, but not that in milk. After IV administration of spiramycin adipate, the lymph concentration was almost identical to that in plasma. After intramammary injection of procaine benzylpenicillin (400 mg), in combination with the same amount of dihydrostreptomycin sulfate, into 2 udder quarters each, mean PC in the lymph of 3.5 micrograms/ml and 8.4 micrograms/ml, respectively, were obtained 6 hours after injection. In plasma, the mean PC of benzylpenicillin (0.07 micrograms/ml) and of dihydrostreptomycin sulfate (0.85 micrograms/ml) were obtained after 4 and 6 hours, respectively. In milk from the nontreated quarters, a mean concentration of 5 ng of benzylpenicillin/ml was obtained, whereas dihydrostreptomycin sulfate (greater than or equal to 0.3 microgram/ml) was not detected.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Phenotypic variations among enterotoxinogenic Escherichia coli from Swedish piglets with diarrhoea.
Escherichia coli strains causing diarrhoea in Swedish piglets were isolated; this investigation was made over a 20-year period, from 1964 to 1984. Many of the isolates belonged to O-groups 8, 141 and 149. These strains were separated into different phenotypes with the aid of a new method, "biochemical fingerprinting". This method has been especially designed to sort E. coli-isolates into various phenotypes based on a pattern of quantitatively measured biochemical reactions. It was found that most pathogenic isolates carrying O-antigen 8 belonged to the same phenotype. This phenotype was common in the 1960's, but later it disappeared from the population and was replaced by a wide variety of different phenotypes, most of them non-enterotoxinogenic, but still belonging to O-group 8. In O-group 141 one phenotype dominated in the 1960's, but in the 1970's a new phenotype appeared, which further increased in number in the 1980's. By contrast, in the O-group 149 practically all strains isolated during the 20-year period were found to carry the relevant virulence factors and belong to the same phenotype.
Animals↗
Supracondylar fracture of the femur following Attenborough stabilized knee arthroplasty treated by a long-stem prosthesis plus internal fixation.
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Aged↗