Search

Investigations of the equine peripheral vascular system have been constrained by the lack of a non-invasive method of examining the arteries and veins of the limbs of the conscious horse. Precise correlations were established between the gross anatomical features of the peripheral vessels and their B-mode sonographic appearance in each thoracic limb of 35 horses. A sonographic imaging protocol was established. Additional Doppler sonographic recordings defined the arterial waveforms and demonstrated that blood flow to the foot could be evaluated in the lateral proper digital artery, distal to the level of the coronary band. Valves (with 2-4 cusps) were identified in the lumina of the medial and lateral palmar common digital veins and those of the medial and lateral palmar proper digital veins. Spontaneous echo contrast, a smoke-like haze of echoic blood, was seen in the lateral and medial palmar common digital veins, the distal deep palmar venous arch and communicating branches, and the palmar proper digital veins, and occasionally seen in the distal deep palmar arterial arch and distal proper palmar digital arteries. The value of duplex sonography (B-mode and Doppler) for anatomical and physiological studies of the peripheral vasculature of the horse was clearly established. Such data could be applied to the investigation of diseases affecting the peripheral circulation.

Quasi-three-dimensional volume imaging provides an inexpensive means of evaluating the usefulness of three-dimensional imaging. The technique works most efficiently with water-skin interfaces and therefore we investigated its application in obstetrical ultrasonography. Three-dimensional perspectives of the normal and abnormal fetal head and face were spectacular and at times provided more information than the two-dimensional images. The ability of an inexperienced observer to interpret the three-dimensional image more easily may have a role in training sonographers and counseling parents whose fetuses have structural defects. Volume imaging has certain limitations and can only be used as a complementary technique.

Real-time three-dimensional views of the fetus can be obtained with minor modification to conventional scanners. The modification consists of placing a divergent lens in the out-of-scan plane of the transducer to generate a beam fan-beam in the insonated volume. All of the echoes from which insonates a volume rather than a slice of tissue. Scanning is performed using oblique angles of incidence to provide total reflection conditions. Echoes are then received only from anterior surfaces, automatically generating the three-dimensional views. Intriguing portrayal of fetal detail can be obtained with this form of imaging which is likely to expand the clinical utility of sonographic examinations. Copyright © 1994 International Society of Ultrasound in Obstetrics and Gynecology

The reaction of selenium tetrachloride with the dichlorothiophene diselenolate 3,4-C4Cl2S(SeLi)2 gives triselenole (I) in 38% yield. Purification of I is difficult due to the occurrence of a facile decomposition on attempted dissolution in a variety of solvents.

Several studies have suggested that dietary protein quality may be an important determinant in the natural history of renal disease. We have therefore studied the effects of a predominantly vegetarian diet in eight patients with Type 1 diabetes mellitus and an albumin excretion rate (AER) in excess of 30 micrograms min-1. The AER was measured after an 8-week run-in period on the patient's usual diet, and again after 8 weeks of a predominantly vegetarian diet in which the proportion of vegetable protein was supplemented in order to minimize the reduction in total dietary protein intake. The median fractional albumin clearance fell during the study from an initial value of 188 x 10(-+) (range 58-810 x 10(-4)) at the end of the run-in period to 87 x 10(-4) (23-829 x 10(-4)) at the end of the period on low animal protein diet (difference 79 x 10(-4) (95% Cl 9-149 x 10(-4)), p less than 0.05). The AER then returned to values similar to those obtained at the beginning of the study after a further 8 weeks in those patients returning to their usual diet. No significant changes in blood glucose control or in arterial pressure were observed. A predominantly vegetarian diet may therefore have important beneficial effects on diabetic nephropathy without the need for a heavily restricted total protein intake.

Transvaginal images, under matched conditions, are in general superior in quality to transabdominal sonograms. The difference is, however, not dramatic and instances frequently occur when the same quality and even inferior images are obtained on transvaginal examinations. The dominant factor is the amount of overlying tissues. For the same thickness, subcutaneous tissues have greater degrading characteristics. Subcutaneous tissues also mar the quality of images by giving rise to strong multiple reflection artifacts. The major factors for image degradation are associated with a moderate increase in the width of the ultrasonic beam and a large increase in the side lobes. The dramatic superiority of transvaginal imaging described in previous comparison studies is due principally to the use of higher frequencies, more strongly focused beams and closer positioning of tissues to the transducer. Copyright © 1991 International Society of Ultrasound in Obstetrics and Gynecology

Summary. The waveforms of vessels supplying the ovaries of women on an in-vitro fertilization (IVF) programme were studied using transvaginal B-mode and Doppler ultrasound. There were 125 scans recorded in 65 women at weekly intervals from 3 days after embryo transfer or 5 days after gamete intrafallopian transfer (GIFT) until confirmation of pregnancy or onset of menses. At each examination the signals obtained from vessels supplying the ovaries were recorded and quantified using a resistance index (RI). Fifteen patients became pregnant of whom one has subsequently miscarried. There was a highly significant difference in the RI values between patients who became pregnant and those who did not; no patient who became pregnant had a RI greater than 0.5. Oestrogen to progesterone ratios were calculated in the subgroup of non-pregnant patients and there was no correlation between these values and the RI values. This new technique enables prediction of IVF treatment failure earlier than has been reported previously and may reflect the inadequacy of the corpus luteum.