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Biomedical subjects

R Millner

Publications and source records attributed to R Millner.

At least 19 recordsLinked to original sources
PubMed2000

Direct measurement of sound velocity in various specimens of breast tissue.

RATIONALE AND OBJECTIVES: Previous studies using ultrasound CT or clinical amplitude/velocity reconstruction imaging ultrasound may indicate that cancers differ from normal breast tissue by increased sound velocity. However, only limited experience with direct measurements of sound velocity exists. This study aimed to investigate sound velocity measured directly in a variety of breast specimens. METHODS: Sound velocity was measured directly by forceps in fresh breast specimens chosen to contain one type of tissue only. Eighty specimens (31 cancers, 18 benign changes of glandular/fibrous tissue, 22 fatty tissues, 5 fibroadenomas, 2 compound tissues, 1 phylloides tumor, and 1 inflammation) were analyzed. RESULTS: Ultrasound velocities in carcinoma, benign changes, fibroadenoma, inflammation, and the phylloides tumor were very similar, with almost complete overlap. In contrary, the ultrasound velocity of fatty tissue was significantly lower. Compound tissues containing fat had an intermediate sound velocity. CONCLUSIONS: Sound velocity may add complementary information to echogenicity (B-scan). Because fat lobules exhibit low ultrasound velocity and carcinomas do not, a locally exact combination of ultrasound velocity information and reflexivity information should allow improved breast cancer detection by ultrasound.

Breast Diseases↗
PubMed2000

Acute renal failure after cardiopulmonary bypass: a possible association with drugs of the fibrate group.

BACKGROUND: Renal failure is a recognized, but infrequent, complication following cardiac surgery. The causes for this condition are multifactorial, and a major concern is that the occurrence of postoperative acute renal failure is still associated with a high mortality rate. METHODS AND MATERIALS: We report unexpected acute renal failure occurring in 4 patients after uncomplicated cardiac surgery. Each patient was taking a fibric acid derivative at the time of surgery. Renal failure occurred rapidly within 3 days of surgery and was associated with increased concentrations of skeletal muscle-derived creatine kinase (CK). One patient developed myoglobinuria, and another developed a malignant hyperthermia-like syndrome. CONCLUSIONS: These cases show that patients receiving lipid lowering medications could be at higher risk of developing acute renal failure after cardiac surgery. This association merits careful evaluation in large prospective studies and, if proved, would suggest that patients taking either statins or fibrates should discontinue doing so before cardiac surgery.

Acute Kidney Injury↗
PubMed1999

[Direct in-vitro measurement of ultrasound velocity in carcinomas, mastopathic tissue, fatty tissue and fibroadenomas of the female breast].

PURPOSE: The study aimed to investigate ultrasound velocity (SV) in carcinomas, fibrocystic changes, fibroadenomas and fatty tissue of the female breast by means of direct in-vitro measurements. We intended to test whether or not differences in SV exist between the various types of tissue and whether the SV is a useful criterion to differentiate the different tissues. METHOD: SV was measured by comparing transmission time of the ultrasound beam through the specimen and through water. Altogether 40 specimens (12 cancer, 14 fibrocystic changes = FCD, 10 fatty tissues, 3 fibroadenomas, and 1 mixed tissue) were analysed. RESULTS: Velocity differed significantly between fat (1478.5 +/- 6.5 m/s) and tumor (1523.1 +/- 5.9 m/s) (p approximately 10(-11)) and between fat and FCD (1526.0 +/- 9.0 m/s) (p approximately 10(-12)). No significant differences and much overlap were seen between the ultrasound velocities of tumors and FCD. Ultrasound velocity in fibroadenomas (1533.2 +/- 3.8 m/s) was comparable with that in carcinomas and FCD. CONCLUSIONS: We conclude that ultrasound velocity may add complementary information to echogenicity (B-scan). Thus, a locally exact correlation of echogenicity and sound velocity might allow for an improved tissue characterization.

Adipose Tissue↗
PubMed1997

Transesophageal echocardiographic detection of complications after Cabrol's procedure.

Cabrol's procedure represents an improvement on earlier surgical techniques used in the management of a patient with aortic insufficiency associated with an aneurysm of the ascending aorta. We report a patient in whom the diagnosis of complications after a Cabrol procedure was facilitated by transesophageal echocardiography. The role of transesophageal echocardiography in the follow-up of these patients is discussed.

Abscess↗
PubMed1995

Effects of ultrasound on agglutination and aggregation of human erythrocytes in vitro.

A new experimental approach has shown that human erythrocytes of different blood groups were induced to form more agglutinates at a sound pressure of 70-240 kPa in vitro than the control erythrocytes. Similar effects were observed for alcian blue and dextran stimulated aggregation and for spontaneous aggregation. The increase of agglutination or aggregation was reversible. Heating and acoustic cavitation were shown not to be responsible for this effect. Bulk fluid movement produced by ultrasound irradiation appeared to cause the described phenomenon. Possible underlying mechanisms connecting the acoustic streaming and agglutination or aggregation behaviour of the cells are proposed.

Alcian Blue↗
PubMed1993

Effects of ultrasound on the steady-state transmembrane pH gradient and the permeability of acetic acid through bilayer lipid membranes.

The irradiation of bilayer lipid membranes with continuous ultrasound of a frequency of 8.2 MHz and a spacial peak time average (SPTA) intensity of 0.4 W/cm2 reduces the thickness of the unstirred layer up to 40% of its initial value under our conditions. This result was obtained from measurements of the transmembrane potential which appears after the addition of a protonophore in the presence of a gradient of acetic acid. Ultrasound exposure decreases this potential when the pH of the buffer solutions is much higher than the pK of CH3COOH and has no effect at low pH values. The latter can be explained by a simultaneous increase of the permeability of acetic acid and the buffer substances, respectively, due to ultrasound irradiation.

Acetates↗
PubMed1993

[Assessment of hemodynamics in the cerebral cortex in newborn infants].

Determinations of blood velocity in vessels of cerebral cortex have been done using a 20 MHz impulse Doppler unit. In comparison we registered the blood flow pulsation curves at the anterior cerebral artery with aid of a 5 MHz-cw-Doppler system. The peripheral resistance index was calculated and it could be proved a strong correlation between the results of the anterior cerebral artery and the vessels of cerebral cortex. Another study showed that the results of the method could be reproduced. The problem of the impulse Doppler examinations of cerebral cortical vessels is the fact, that the exact topography of the vessels examined cannot be defined exactly.

Blood Flow Velocity↗
PubMed1992

[Sonographic evaluation of changes in testicular tissue by ultrasound spectroscopy].

Experimental investigations were carried out under in vitro conditions on 25 normal human testicular specimens and on 60 pathological testicular specimens to ascertain the ultrasound attenuation using an ultrasound spectroscopic measuring technique. The ultrasound attenuation was established by calculating the ultrasound attenuation coefficient alpha. The average values of ultrasound attenuation (alpha) in normal testicular tissue were distinctly lower than in pathologically altered testicular specimens. A comparison of the various pathologically altered testes showed higher attenuation in the case of malignant neoplasms whilst the highest average values of wore recorded for non-neoplastic pathological alterations in the testicular tissue. The results of the investigations show that certain alterations in the tissue can be ascertained by ultrasound spectroscopy. The analysis of further acoustic parameters in future investigations, such as ultrasound back-scattering and velocity, along with the recording of ultrasound attenuation, gives scope for improved assessment of the tissue. Thus ultrasound spectroscopy increases the sonographic accuracy acquired through analysis and the weighing up of symptoms of tissue dependent ultrasound parameters.

Adolescent↗
PubMed1992

Doppler sonographic pulse curve analysis for estimation of the haemodynamic function.

Experience with Doppler sonographic pulse curve analysis is given from 40 glaucoma patients (examination of the temporal posterior ciliary artery), and from premature babies (blood flow in the anterior cerebral artery). In the latter group the reaction to pain and stress connected with blood sampling was studied. In the glaucoma patients focus was on the influence of IOP level on vascular autoregulation, and the possible response to therapy with beta-blockers. Describing an averaging technique, methodological problems are discussed as relevant for the detection of changes in flow and velocity in small blood vessels.

Adrenergic beta-Antagonists↗
PubMed1990

[Experimental studies of the effect of fixation time on ultrasound extinction in formalin-fixed testicular tissue].

The influence of fixation time on the ultrasound damping was investigated in vitro in both normal and altered formalin-fixed testicular tissue. By means of ultrasound spectroscopy the ultrasound damping coefficient alpha is estimated. The results of measurements in different time intervals after onset of fixation did show that in both normal and altered testicular tissue only slight changes of ultrasound damping was found. Therefore, the influence of fixation time could be neglected.

Fixatives↗
PubMed1990

[Effect of various fixation agents on ultrasound damping in normal and pathological testicular tissues].

In normal and pathological testicular tissue the influence of various fixing agents (Formalin solution, Bouins solution, Hellys solution, Carnoys solution) concerning the acoustical properties of testicular tissue was examined. By means of an ultrasound spectroscopic measurement technique the ultrasound damping was registered by calculation of the ultrasound damping coefficient alpha. The results show that the most lower alpha values were obtained by fixation with formalin solution as well in normal as in altered testicular tissue. The results of fixation according to Helly, Carnoy and Bouin did show markedly differences. Therefore, the fixation of testicular tissue using formalin solution is the best way for experimental examinations of the ultrasound damping behaviour.

Dysgerminoma↗
PubMed1990

[Influence of examining temperature on the ultrasound attenuation in testicular tissue].

By means of an ultrasound spectroscopic measurement technique the influence of examining temperature on the ultrasound attenuation was experimentally investigated on formalin-fixed normal and altered testicular tissue. In the examined tissue specimens a temperature-dependent change of ultrasound attenuation (alpha on 6 MHz) was found in the temperature area between 10 and 50 degrees C. In the altered testicular tissue a higher damping decline could be observed. On the measuring points the specimens were examined by light microscopy.

Dysgerminoma↗
PubMed1990

[Experimental investigations on the effect of the transducer-specimen distance on the ultrasound attenuation of formalin-fixed testicular tissue].

Additional information on the tissue structure are possible by estimation of sound physical parameters in comparison with normal B-scan ultrasonography, especially the frequency-dependent ultrasound attenuation. The ultrasound attenuation measurements were made on histochemical normal and pathological testicular tissue with changing transducer-specimen distance. No markedly difference in damaging behaviour was found between normal and pathological testicular tissue at different distances.

Fixatives↗