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Biomedical subjects

C Anagnostopoulos

Publications and source records attributed to C Anagnostopoulos.

At least 55 records · Page 3Linked to original sources
PubMed1987

[90 fine-needle punctures for diagnosis of the upper abdomen under ultrasonic guidance. Contribution of cyto- and histologic analysis].

Fine needle puncture was performed of upper abdomen in 19 cases. The method is rapid, reliable, of low cost and only weakly traumatic. The recent possibility of coupling histologic and cytologic analysis with fine needles provides improved results by increasing diagnostic precision and identification of malignant tumors and benign tumors of difficult cytologic diagnosis.

Abdomen↗
PubMed1985

[Aberrant renal papilla. Apropos of a case].

The authors report a case of aberrant renal papilla. This exceptional benign congenital anomaly produces a pelvo-calyceal filling defect. Emphasis is made on the major interest of intraoperative nephroscopy in order to avoid inappropriate surgery since ultrasonography does not seem to bring contributing positive data.

Humans↗
PubMed1983

Bacillus subtilis strains carrying two non-tandem duplications of the trpE-ilvA and the purB-tre regions of the chromosome.

Bacillus subtilis strains possessing the trpE30 marker (splitting of the trpE locus and a non-tandem duplication of chromosome segment Ib: purB-tre) when transformed or transduced to tryptophan independence mainly give rise to haploid cells with the genetic structure of strain 168. However, among the Trp+ transformants or transductants about 10% are merodiploid carrying a non-tandem duplication of segment C (trpE-ilvA) while maintaining that of segment Ib. Linkage and segregation studies made it possible to determine their genetic structure, which can be represented by three different maps. In map a the copies of Ib are inverted repeats and one of them is flanked by two direct repeats of segment C; in map b two Ib-C segments are inverted repeats and in map c the copies of C are inverted repeats with one of them flanked by direct repeats of Ib. It is proposed that transition from map a to map b and then to map c, and vice versa, may occur by recombination between inverted repeats of either Ib or C. The merodiploids are unstable, recombination between direct repeats leading to haploid cells of 168-type structure. The models proposed for merodiploid formation call for fusion of two recipient chromosomes mediated by the donor segment and recombination between copies of a DNA sequence of the two chromosomes located in different regions. In the case of PBS-1 mediated transduction the greater length of the donor DNA segment makes it possible to obtain the merodiploids with a single recipient chromosome and this needs only a slight modification of the models. No trpE30+ merodiploids are found in transformation when the recipient carries a deletion of the SP beta prophage, or in transduction when both donor and recipient possess this deletion. These results indicate that the homologous sequences involved may be part of the SP beta prophage or that a sequence of bacterial DNA has a good homology with it.

Bacillus subtilis↗
PubMed1982

Genetic structure and internal rearrangements of stable merodiploids from Bacillus subtilis strains carrying the trpE26 mutation.

Transformation and transduction to tryptophan independence of strains of Bacillus subtilis carrying the "trpE26" chromosomal aberrations (a translocation and an inversion) with a "normal" 168 type strain as donor induce a tandem duplication of the thrA-ilvA region of the chromosome. The clones possessing this unstable duplication segregate besides the Trp- some stable Trp+ cells which retain only part of the duplication (the trpE-ilvA region) in nontandem configuration. Such clones may also be produced directly during the crosses. The genetic map of these clones (designated as class I stable merodiploids) was constructed: they possess the translocation and the inversion of the trpE26 parental strain. Another type of stable Trp+ clones (class II) also appears, although more rarely, in similar crosses. Studies on their genetic structure revealed that they are haploid for the trpE-ilvA region and carry a nontandem duplication of the thrA-trpE region. In these clones the cysB-tre region has the orientation of the 168 type strain. The duplications in both classes are stable, that of class I being more stable than that of class II where loss of one copy of the thrA-trpE region leads to about 1% haploid cells. Detailed genetic studies on heterozygous clones from both classes have shown exchange of alleles between copies of the nontandem duplications. Models are proposed for the formation of each class of merodiploids and for recombination events taking place in them. These models imply recombination at sequences of intrachromosomal homology and (or) introduction of heterologous junctions ("novel joints") by transformation or transduction.

Bacillus subtilis↗
PubMed1982

Replication terminus of the Bacillus subtilis chromosome.

Bidirectional replication of the Bacillus subtilis chromosome terminates at a point on the circular chromosome which is symmetrically opposite to the replication origin. Since replication rates are similar in both "halves" of the chromosome, termination presumably occurs at the meeting point of the two replication forks. To investigate whether the DNA sequence of this region of the chromosome contributes to the termination event, we have determined the latest replicating region of a chromosome in which this DNA sequence is no longer symmetrically opposite to the origin. The merodiploid strain GSY1127 has a very large nontandem duplication (approximately 25% of the total chromosome length) in the left-hand half of the chromosome, so that size and symmetry of this chromosome are grossly different from those of normal strains. We have examined the replication order of genetic markers in this strain by measuring subtilis terminal marker for replication remains a terminal marker in the merodiploid, i.e., replicates later than a marker situated symmetrically opposite to the replication origin. These results were supported by replication orders determined by pulse-density transfer experiments during synchronous replication. The data obtained indicate that there is a preferred site for the termination of replication in the B. subtilis chromosome.

Bacillus subtilis↗
PubMed1981

Myocardial protection from permanent injury during aortic cross-clamping: effectiveness of pharmacological cardiac arrest combined with topical cardiac hypothermia.

In two groups of animals (6 and 9 dogs), the aorta was cross-clamped 60 and 90 minutes, respectively, during hypothermic cardiopulmonary bypass. Immediately after cross-clamping, pharmacological cardiac arrest was induced by injecting 100 ml of a cold cardioplegic solution into the aortic root. Topical cardiac hypothermia was added. In hearts undergoing 90 minutes of ischemia, a repeat injection of the cardioplegic solution was done at 45 minutes. In 14 dogs (control group), only topical cardiac hypothermia was instituted for myocardial protection during 60 minutes of ischemia. Seven weeks after operation the surviving animals (6 in each group) were killed. Study of myocardial performance failed to demonstrate significant differences among the groups. Microscopic examination of transmural samples taken from anatomically defined sides of both ventricles, disclosed isolated, punctuate subendocardial scars in only 2 hearts of the control group. All the hearts having 90 minutes of pharmacological cardiac arrest and topical cardiac hypothermia exhibited diffuse fibrosis replacing 10 to 20% of the left ventricular myocardium. Extent and incidence of fibrosis were significantly higher in these hearts in comparison to those of the other groups. We conclude that pharmacological cardiac arrest plus topical cardiac hypothermia makes a safe and efficient method of myocardial protection during aortic cross-clamping only if the ischemic intervals is limited to 60 minutes. It cannot prevent permanent myocardial injury if the ischemic arrest is extended to 90 minutes.

Animals↗
PubMed1981

Substrate specificity and adenosine triphosphatase activity of the ATP-dependent deoxyribonuclease of Bacillus subtilis.

Studies on the specificity of the ATP-dependent DNase of Bacillus subtilis 168, carried out with pure enzyme at the optimal conditions for its action, have shown that the substrate is double-stranded linear DNA. Linear single-stranded DNA (separated strands of B. subtilis DNA and linear phage fd DNA) is not attacked, neither are there any circular forms (supercoiled or nicked simian virus 40 and circular single-stranded fd DNAs). The double-stranded DNA can be completely hydrolysed, the limit products being, almost exclusively, mononucleotides. The presence of terminal phosphate residues in the substrate (either at the 3' or the 5' end) is not necessary for enzyme action. This DNase appears therefore to be an exonuclease processively liberating mononucleotides from both strands of the native linear DNA. ATP (indispensable for the DNase reaction) is also hydrolysed by the enzyme, to ADP and inorganic orthophosphate (Pi) in the presence of DNA. The apparent Km for ATP, in the ATPase reaction, is 0.15 mM. At high ATP concentrations, which inhibit the DNase activity, there is activation of the ATPase reaction. Three molecules of ATP are consumed for each DNA phosphodiester bond split, at optimal conditions for DNase activity.

Adenosine Triphosphatases↗
PubMed1979

The prosthetic (Teflon) central aortopulmonary shunt for cyanotic infants less than three weeks old: results and long-term follow-up.

The expanded microporous polytetrafluoroethylene (PTFE) 4 mm vascular prosthesis has been used to create a central aortopulmonary shunt in 20 critically ill infants less than 3 weeks old. The infants ranged from 1 to 18 days old (5.25 days), and from 1.5 to 4.0 kg (2.9 kg). Conduit length ranged from 2 to 6 cm (4 cm). Sixteen patients had atresia of the tricuspid or pulmonary valve. There were 6 early deaths (30%), only 1 of which was shunt related. The mean preoperative arterial oxygen saturation was 62% (range, 33 to 80%), and mean postoperative saturation was 87% (range, 78 to 90%). There were 5 late deaths, 1 probably caused by shunt failure. Nine long-term survivors have done well. Follow-up ranges from 1 to 36 months (18 months). Factors influencing conduit function are length, technical considerations, and pulmonary vascular resistance. Late restudy in 5 of 9 survivors confirms patency and demonstrates bidirectional pulmonary blood flow. Since PTFE shunt flow capability is fixed, the infant may require repair or a second shunt within 24 months of the initial procedure.

Aorta↗
PubMed1979

Taussig-Bing anomaly with straddling mitral valve.

Five patients with the left-sided or intermediate type (Lev) of the Taussig-Bing anomaly were found to have an associated straddling of the mitral valve. In four patients the anomaly of the mitral valve was not recognized preoperatively, and all four died postoperatively. The persistent subpulmonic obstruction caused by the abnormal attachment of the anterior mitral leaflet is considered a significant factor in the poor operative outcome. Retrospective study of angiograms in these four patients revealed diagnostic clues of straddling mitral valve which enabled us to diagnose a fifth patient angiographically and confirm the diagnosis by cross-sectional echocardiography. A surgical approach to correct this association of abnormalities is proposed which avoids operating upon the mitral valve. Its function is thereby preserved, yet the hemodynamic problem caused by the straddling is bypassed. The fifth patient in this series was successfully treated by the proposed operative method.

Adolescent↗
PubMed1978

Echocardiographic diagnosis of partial pericardial constriction of the left ventricle.

In a patient with hemodynamic findings typical of severe, generalized pericardial constriction, echocardiography demonstrated partial constriction of the left ventricle; the patient had partial pericardiectomy 17 years earlier. Diagnosis was confirmed by angiocardiography and at surgery. Echocardiography suggested penetration of the myocardium at places by pericardial calcification; this finding was confirmed at surgery.

Angiocardiography↗
PubMed1978

Blockade of tissue uptake of the antineoplastic agent, doxorubicin.

Myocardial uptake of doxorubicin (Adriamycin) and its inhibition by digoxin and propranolol were studied in paced, isolated perfused cat hearts using tritiated doxorubicin. Contractility was studied using a Walton-Brody strain gauge arch and its first derivative. Coronary blood flow was measured by collecting the effluent from the heart. The myocardial content of doxorubicin was 0.069 +/- 0.101 nmol/mg after 30 minutes. Combined administration of doxorubicin and digoxin reduced the myocardial content of doxorubicin to 0.025 +/- 0.010 nmol/mg (P less than .02). The combination increased contractility compared with doxorubicin alone and increased coronary blood flow compared with digoxin alone. The reduction in the myocardial content of digoxin by doxorubicin was not significant. Propranolol also reduced the myocardial uptake of doxorubicin (P less than .05) without changing coronary blood flow and without further reducing contractility. Thus, both propranolol and digoxin merit evaluation in preventing doxorubicin cardiotoxicity.

Animals↗
PubMed1977

Does local cardiac hypothermia during cardiopulmonary bypass protect the myocardium from long-term morphological and functional injury?

Twenty-eight dogs were subjected to 90 minutes of hypothermic (30 degrees C) cardiopulmonary bypass with moderate hemodilution. In 6 dogs the heart was vented and beating for 60 minutes. Eight dogs underwent ventricular fibrillation with coronary perfusion (VF + CP). In 14 dogs the aorta was cross-clamped for 60 minutes while the myocardium was protected by local cardiac hypothermia (ICA + LCH). Eighteen animals survived. Hemodynamic studies at seven weeks revealed no major differences among the three groups. At postmortem examination, no gross scarring was noted in any heart. Microscopical examination of 14 hearts was completely-normal. In the VF + CP group, 2 hearts had isolated microscopical scars. Similar linear subendocardial scars (less than or equal to 1.5 X 0.5 mm) were noted in 2 hearts subjected to ICA + LCH. Survival after 60 minutes of VF + CP or ICA + LCH did not result in long-term morphological injury to or functional impairment of the myocardium.

Animals↗
PubMed1977

The influence of prostaglandins E1 and E2 on ouabain cardiotoxicity in the cat.

The capacity of prostaglandins E1 (PGE1) and E2 (PGE2) to influence the lethal dose and lethal myocardial content of ouabain was studied in intact cats and cats whose spinal cords had been transected. The administration of PGE1 and PGE2 to intact cats was associated with an increase in lethal dose and ventricular content of ouabain. Spinal cord transection alone was also associated with an increase in lethal dose and ventricular content of ouabain. The administration of either PGE1 and PGE2 to animals whose spinal cords had been transected changed neither the lethal dose nor the lethal ventricular content of ouabain compared with cats whose spinal cords were transected but who received only ouabain. The present data suggest that PGE1 and PGE2 are effective agents for prophylaxis of ouabain-induced arrhythmias in the cat. The failure to observe an additional antiarrhythmic effect in animals whose spinal cords had been transected implies that the nervous system plays an important role in the antiarrhythmic action of the prostaglandins.

Animals↗