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Biomedical subjects

X J Hu

Publications and source records attributed to X J Hu.

29 records · Page 2Linked to original sources
PubMed1989

Choice of lasers for laser angioplasty.

Thrombi in test-tube, intraarterial thrombi and pig aorta wall were in vitro irradiated with continuous CO2 laser, short pulsal and ultrashort pulsal YAG laser (with pulse-width of 10 ns and 40 ps, respectively) and their double frequency laser and excimer laser with a wave-length of 308 nm and pulse-width of 20 ns. Their effect of vaporizing and ablating (photodecomposing) thrombi and their thermal injuring effect on adjacent tissues were compared and assessed in order to select optimal laser with little thermal injuring and more rapid vaporizing or ablating thrombi effect for laser angioplasty. The experimental results showed that excimer laser, ultrashort pulsal YAG laser and its double frequency laser, and double frequency laser of short pulsal YAG laser, with laser beam and blood vessel kept in a coaxial position, can effectively vaporize or ablate thrombi without thermal injury to vessel wall. So they may be used for laser angioplasty. Of them, especially, excimer laser and double frequency laser of ultrashort pulsal YAG laser have short wave-length and high peak power, and more effectively ablate thrombi than others, so they proved to be optimal lasers for laser angioplasty.

Angioplasty, Balloon↗
PubMed1985

[Evaluation of the atrial contribution to ventricular filling in patients with DDD pacemakers].

To evaluate the usefulness of physiologic cardiac pacing, the trasmitral flow velocity was recorded using the pulsed Doppler method combined with 2-D echocardiography in 14 patients in whom a DDD pacemaker was implanted. DDD pacemakers were programmed to atrioventricular (AV) sequential pacing with AV intervals of 50, 100, 150, 200 and 250 msec, and VVI pacing modes at a heart rate of 70 bpm. The time-velocity integral (TVI) of the left ventricular (LV) inflow curve was obtained by digitizing the outline of the tracings and expressed in the percentage of that of AV sequential pacing with AV interval of 150 msec (the percent LV filling volume). The percent LV filling volume was 75% for 50 msec, 89% for 100 msec, 96% for 200 msec and 90% for 250 msec of an AV interval in AV sequential pacing. It was significantly smaller at AV intervals of 50, 100 and 250 msec than at an AV interval of 150 msec. It was significantly smaller (68%) in VVI pacing than at AV intervals of 100, 150, 200 and 250 msec in AV sequential pacing. The left atrial (LA) contribution to LV filling was assessed in terms of the fraction of TVI during LA contraction to that during total LV filling at the optimal AV interval (A/Fmax). The optimal AV interval was defined as the interval at which the maximum LV filling volume was achieved in individual patients. The A/Fmax showed a positive correlation with the percent increase of LV inflow volume, with conversion from VVI to AV sequential pacing with the optimal AV interval. It also showed a positive correlation with age. These results suggested that the LV inflow volume was greater in AV sequential pacing with the optimal AV interval than in VVI pacing, especially in patients with a large A/Fmax. In conclusion, pulsed Doppler echocardiography could be a useful, non-invasive technique to determine the indications for implanting a DDD pacemaker and the optimal AV interval in patients in whom DDD pacemakers are implanted.

Adult↗
PubMedDate not supplied

Group sequential analyses for the mean function of a repeated measure process.

In many clinical trials, treatment efficacy is based upon response to a biological marker that is measured repeatedly during the course of follow-up. However, in some of these trials it is not clear, a priori, how treatment effects on the marker may manifest themselves or what kinds of effects are clinically meaningful and/or acceptable. It is, therefore, desirable to allow flexibility in design and monitoring process by not prespecifying a stopping rule or even the parameter on which inferences will be based. Using the more general results in Hu and Lagakos, this paper extends the idea of the repeated confidence intervals for a parameter (Jennison and Turnbull) to repeated confidence bands for the mean function of a repeated measure process. We illustrate the approach and some considerations in its application with the results of a recent AIDS clinical trial.

Adult↗
PubMedDate not supplied

Morphological diversity in terminals of W-type retinal ganglion cells at projection sites in cat brain.

The morphological features of retinal terminals in cat brain were examined at sites where projections of W-type ganglion cells predominate. These included the parvicellular C laminae of the dorsal lateral geniculate nucleus, the ventral lateral geniculate nucleus, stratum griseum superficiale of the superior colliculus, and the suprachiasmatic nucleus. Positive identification of retinal terminals was achieved following anterograde transport of intravitreally injected native or wheat germ agglutinin-conjugated horseradish peroxidase. In contrast to the classic features of retinal terminals as defined from sites where X- and Y-type ganglion cells predominate, i.e. round synaptic vesicles, large profiles, and pale mitochondria, substantial numbers of terminals in W-cell rich areas were found to contain dark mitochondria. Synaptic vesicles, although consistently round, were typically smaller in terminals with dark mitochondria than in those with pale mitochondria. These findings indicate a diversity among terminals of W-cells and suggest that such terminals cannot be distinguished on the basis of limited morphological criteria.

Animals↗