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Biomedical subjects

K J Taylor

Publications and source records attributed to K J Taylor.

At least 91 records · Page 5Linked to original sources
PubMed1988

Investigation of Doppler waveforms in porcine renal allografts: Doppler-pathologic correlation.

A porcine model was devised to investigate Doppler waveforms in dysfunctional renal allografts. NIH miniature pigs served as allografts donors and recipients. Renal transplantation was effected into the recipient pelvis while the left normotopic kidney was subjected to warm ischemia in order to induce acute tubular necrosis (ATN). Doppler demonstration of allograft arterial occlusion in six animals was confirmed at surgery. Increased pulsatility of intrarenal arterial signals constituted evidence of vascular rejection in two animals. Biopsies confirmed the diagnosis in both cases. Histologic changes of ATN were identified in two native kidneys subjected to ischemia. No waveform or pulsatility alterations were observed in these animals. The porcine model provides for the investigation of allograft Doppler waveforms in a controlled setting with free access to biopsy and operative pathologic correlation.

Animals↗
PubMed1988

Detection of neovascular signals in a 3 day Walker 256 rat carcinoma by CW Doppler ultrasound.

An animal model was used to study tumor blood flow by the Doppler CW technique. The objective was to determine when neovascularity could be detected as a function of tumor size and time since transplantation. A Walker 256 carcinosarcoma tumor was inoculated into the flank of 17 Sprague-Dawley rats. Doppler examinations, using a 9 MHz CW probe, were performed daily from day 0 to day 7. The contralateral flank was used as a control. No signals were detected from the control side nor from the inoculated side until day 3. By day 3, Doppler signals could be easily detected in all tumor implants with a minimum weight of only 50 mg. These signals showed a mean systolic frequency shift of 3.3 +/- 0.47 kHz at 3 days and 3.46 +/- 0.58 kHz at 7 days. The diastolic Doppler shifted frequency was 1.78 +/- 0.31 kHz at 3 days and 1.88 +/- 0.23 kHz at 7 days giving a Pourcelot index of 0.47 +/- 0.1 at 3 days and 0.46 +/- 0.09 at day 7. These figures indicate the presence of low impedance vessels with high velocity flow such as has been reported in many human tumors. The vascular morphology was further evaluated by digital angiography which demonstrated coincidence between the site of the high velocity Doppler signals and the presence of arteriovenous anastomoses manifested by simultaneous arterial and venous filling. Further infusion techniques using India ink or Microfil showed the chaotic arrangement of tumor vessels located around the growing edge of the tumor implant. The development of such vascularity is a well-recognized prerequisite for tumor growth and invasion.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1988

Transvaginal ultrasonography for the diagnosis of ectopic pregnancy.

The transvaginal (TVU) and transabdominal (TAU) ultrasound approaches were compared in their ability to identify by direct visualization the adnexal mass of ectopic pregnancy. There were 22 patients who had a surgically proven ectopic pregnancy. The TAU approach identified the adnexal mass in 50% and the TVU approach in 91% of the patients (P less than 0.01). Below both previously reported threshold titers for the expected TAU intrauterine sac visualization, at 6500 mIU and 3600 mIU, respectively, the TVU approach allowed the identification of significantly more ectopic adnexal masses than the TAU approach. The results of the present study demonstrate the increased efficacy of TVU over TAU in the direct identification of the adnexal mass associated with ectopic gestation.

Abdomen↗
PubMed1988

Randomized low-dose indomethacin trial for prevention of intraventricular hemorrhage in very low birth weight neonates.

We admitted 36 preterm neonates (600 to 1250 gm birth weight) with normal 6-hour echoencephalograms to a randomized, placebo-controlled prospective trial to determine whether a low dose of indomethacin would prevent germinal matrix or intraventricular hemorrhage and permit adequate urinary output. Between the sixth and tenth postnatal hours, indomethacin (0.1 mg/kg) or placebo was administered intravenously every 24 hours for a total of three doses. Cardiac ultrasound studies to assess the status of the ductus arteriosus were performed at 6 postnatal hours and on day 5. Urinary output, serum electrolytes, serum indomethacin levels, and renal and clotting functions were monitored. No differences in birth weight, gestational age, or Apgar scores were noted between the two groups of infants. Two indomethacin-treated infants and three infants given placebo had significant urinary output difficulties, requiring that the study medication be withheld. Of 19 infants given indomethacin, two had germinal matrix or intraventricular hemorrhage, in comparison with 8 of 17 infants given saline solution (p = 0.02). Of the infants who had a left-to-right patent ductus arteriosus shunt before treatment, 64% of the indomethacin-treated and 33% of the saline solution-treated infants no longer had a patent ductus arteriosus on day 5. Ductal status appeared unrelated to the development of germinal matrix or intraventricular hemorrhage.

Cerebral Hemorrhage↗
PubMed1988

Diagnostic imaging of hepatocellular carcinoma: progress in noninvasive tissue characterization.

Hepatocellular carcinoma (HCC), a common malignancy in the United States with poor prognosis, must be differentiated from hemangioma, focal fat, metastases, and regenerating nodules. Serum alpha-fetoprotein (AFP) levels are not a sensitive method for detection of HCC. High resolution ultrasound has been highly effective in detecting HCC in Japan and Taiwan. Doppler ultrasound can be used to increase the specificity. We review the roles of angiography, computed tomography (CT), and magnetic resonance, to conclude that the Japanese experience has demonstrated the efficacy of screening for HCC in the population at risk using serum AFP and ultrasound with the addition of dynamic CT and angiography where indicated. The continuing poor prognosis of patients with HCC in the United States suggests a failure to apply these methods for the early detection of HCC.

Angiography↗
PubMed1988

Correlation of Doppler US tumor signals with neovascular morphologic features.

Abnormal Doppler ultrasound signals were detected in 44 of 47 patients with primary malignant tumors of the liver, kidney, adrenal gland, or pancreas (94%). Two different signal types were noted: a high-velocity signal (n = 38) with Doppler shifts exceeding 3 kHz (at an insonating frequency of 3 MHz) and a very low-impedance signal (n = 9) demonstrating little systolic-diastolic variation. In three patients, both types were present. In 19 patients, histologic (n = 12) and/or angiographic (n = 16) correlation was available. Among 13 patients with angiographic studies and signals over 3 kHz, arteriovenous shunting was demonstrated in six. The ratio of the systolic to diastolic Doppler shift is a function of vascular impedance. This systolic/diastolic index was less than 3 in eight patients with histologic correlation. All eight had prominent vascular spaces, and the flow in such thin-walled, endothelium-lined spaces would account for the low-impedance signals. Of nine patients with systolic/diastolic indexes of 3 or less and angiographic correlation, three had marked and four had moderate tumor staining.

Adolescent↗
PubMed1988

Tumor vascular signals in renal masses: detection with Doppler US.

The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.

Adolescent↗
PubMed1988

Unusual causes of increased vascular impedance in renal transplants: duplex Doppler evaluation.

Duplex Doppler ultrasound (US) examination of the renal vasculature has proved valuable in assessing the kidney transplant. The normal renal allograft exhibits low-impedance arterial inflow similar to that seen in the normotopic kidney. The authors and others previously reported that a high vascular impedance, defined as either a pulsatility index (PI) greater than 1.8 or a resistive index greater than 0.9, indicates acute vascular rejection (AVR). Although AVR remains the most common cause of increased PI, the authors noted ten episodes among 180 serially followed-up transplants in which abnormal waveforms were clearly not due to rejection. Four other causes of increased vascular impedance are reported, including renal vein obstruction, severe acute tubular necrosis, pyelonephritis, and extrarenal compression of the graft. These new causes only slightly decrease the specificity of high vascular impedance for rejection. Furthermore, the cause can usually be recognized from the clinical history or other US findings.

Acute Kidney Injury↗
PubMed1988

Normal instability of the hip in the neonate: US standards.

In recent years, the use of real-time ultrasonography (US) has enabled dynamic evaluation of the infant hip through a range of motion and stress. Preliminary experience has suggested that a certain amount of instability in the hips of newborns is normal, but no standards have been established. In this study, a group of term neonates whose physical examinations were normal were examined with US on the 1st and 2d days of life. Each hip was imaged in the transverse plane in nonstressed and stressed positions, and movement of the femoral head under stress was quantitated. This displacement under stress was used to establish a normal range of hip instability in neonates. Patterns of hip laxity in boys and girls are identical, and in most infants hip instability diminishes between the 1st and 2d days of life. Our method of quantitating hip instability produces consistent results, with intraobserver 95% confidence intervals of +/- 1.2 mm for each measurement.

Birth Weight↗
PubMed1987

Peripheral blood eosinophil counts and bronchial responsiveness.

Bronchial responsiveness (histamine PC20) and peripheral blood eosinophil counts were measured in 23 asthmatic subjects, of whom 14 were atopic and nine non-atopic. In the group as a whole there was an inverse correlation between baseline eosinophil count and histamine PC20 (r = -0.71; p less than 0.001). For atopic subjects a relationship between eosinophil count and histamine PC20 was observed (r = -0.74; p less than 0.01), but there was no correlation between eosinophil count and baseline FEV1 or baseline FEV1 and histamine PC20. For the non-atopic subjects a similar relationship between eosinophil count and histamine PC20 was seen (r = -0.68; p less than 0.05) and a less significant inverse correlation between baseline eosinophil count and baseline FEV1 (r = -0.65; p less than 0.05). These results show a relationship between eosinophil count and non-specific bronchial responsiveness in both atopic and non-atopic asthma.

Adolescent↗
PubMed1987

Vascular complications in renal allografts: detection with duplex Doppler US.

Renal allografts are subject to many vascular complications. Over a 2-year period, 334 duplex Doppler ultrasonographic (US) examinations were performed in 88 renal allograft recipients. Vascular occlusion on the basis of severe vascular rejection was documented in ten patients (11.4%) for a sensitivity and specificity of 100%. Seven patients, for whom there was clinical and Doppler US evidence for renal artery stenosis, underwent angiography. A significant stenosis was confirmed and treated by angioplasty in four patients; one had an insignificant stenosis in an accessory artery, one had kinking of the renal vessels, and another had normal findings. The most reliable criteria for stenosis were a high-velocity jet exceeding 7.5 kHz and distal turbulence. One arteriovenous fistula was diagnosed by the presence of an intrarenal high-velocity jet. Duplex Doppler US is a useful, noninvasive, and portable initial procedure with which to screen patients for vascular complications of renal transplantation.

Adult↗
PubMed1987

Doppler signal quantitation in renal allografts: comparison in normal and rejecting transplants, with pathologic correlation.

Quantitative duplex Doppler sonography was performed in 55 renal transplant patients during 54 independent episodes of acute rejection, three episodes of chronic rejection, three episodes of acute tubular necrosis (ATN), and 23 occasions of normal graft function. Doppler signals were obtained from four arterial sites in each kidney. Nine patients, in whom signals were absent, were subsequently shown at nephrectomy to have absence of perfusion resulting from severe acute vascular rejection. In each patient with graft dysfunction, biopsy or nephrectomy was performed within 24 hours of the Doppler study. Arterial Doppler signals were quantified using a pulsatility index (PI). Acute rejection produced a significantly higher PI at each arterial site. Receiver-operator characteristics suggest that signals obtained from the segmental arteries are most sensitive to these changes. With a threshold PI of 1.5, the sensitivity of this technique for detection of acute renal allograft rejection is 75%; the specificity is 90%. In acute vascular rejection, the same PI yields a sensitivity of 79% and specificity of 90%. With a cutoff PI of 1.8, a specificity of 100% can be achieved.

Adolescent↗
PubMed1987

Focal liver masses: differential diagnosis with pulsed Doppler US.

Duplex Doppler ultrasound (US) was used in 68 consecutive patients with focal liver lesions, including 12 hepatocellular carcinomas, one cholangiocarcinoma, 37 metastases, 15 hemangiomas, one hemangioendothelioma, and two focal nodular hyperplasias. Of the hepatocellular carcinomas, six were diffusely hyperechoic, two were hypoechoic, two were single hyperechoic lesions, and two were multifocal and hyperechoic. All ten tumors with Doppler shifts of 5 kHz or above proved to be hepatocellular carcinomas. The other two hepatocellular carcinomas showed Doppler shifts of 3 kHz. In contrast, no hemangioma showed shifts above 0.7 kHz, and ten of the 15 gave no detectable signal. Of the metastases, 20 gave no signal and 17 had signals of up to 4 kHz. Three-kilohertz signals were also obtained from a cholangiocarcinoma, a hemangioendothelioma, and focal nodular hyperplasia. Correlation with angiographic findings suggested that the high-velocity Doppler signals were associated with large pressure gradients due to arteriovenous shunting. Duplex Doppler US can therefore aid in the differential diagnosis of diffuse and focal liver lesions.

Aged↗
PubMed1987

Gestational trophoblastic neoplasia: diagnosis with Doppler US.

The sonographic appearance of gestational trophoblastic neoplasia is nonspecific and also seen in complete or partial hydatidiform mole, hydropic degeneration, degenerating fibroids, or ovarian dysgerminomas. Correlation with the serum human chorionic gonadotropin (hCG) level may be helpful since levels exceeding 100,000 IU/L are strongly suggestive of gestational trophoblastic neoplasia. However, low hCG levels may also be found in the presence of this disease. The authors studied six patients who were suspected of having gestational trophoblastic neoplasia. Three of the six proved to have incomplete abortions or molar degeneration. Doppler ultrasound (US) was used to record the signal in the uterine arteries of these patients. The signals were compared with those of three nongravid volunteers and three patients in the first trimester of pregnancy. Analysis of the signals in the uterine artery showed higher systolic and diastolic Doppler shifts in gestational trophoblastic neoplasia when compared with postabortal, gravid, and nongravid signals. These preliminary results indicate that Doppler US has the potential to be clinically useful in the diagnosis of gestational trophoblastic neoplasia.

Abortion, Incomplete↗