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Biomedical subjects

C T Lu

Publications and source records attributed to C T Lu.

18 recordsLinked to original sources
PubMed1992

Strategies for blood screening for the hepatitis C virus and for the human immunodeficiency virus in high risk groups.

For many infectious agents, seroprevalence rate is low but has serious consequences and must therefore be kept out of donated blood supplies. However, screening to ensure the safety of blood supplies has an associated very high cost. For example, in blood banks, detection of all the harmful items in a large number of samples is an expensive and tedious process. The laboratory and statistical approaches to obtain significant savings by the pooling method were discussed from 1943, recently, there have been further discussions of pooling sera as a means to determining the HIV seroprevalence rate in the general population or the weed out all HIV-positive individuals in blood screening. Here we describe a simple mathematical method to weed out all HIV, and HCV seropositive units. The method is designed to maximize possible savings. Two examples illustrate the application of this method in determining the number to be pooled in each stage, and the resulting savings. When the prevalence rate is lower than 2 percent. our method offers savings of over 80 percent.

Blood Donors↗
PubMed1991

Vena Tech vena cava filter: experience and early follow-up.

Vena caval filters, such as the Vena Tech filter, that employ low-profile introducer systems have provided physicians with a variety of options for percutaneous placement. From April 1989 to April 1990, 81 patients underwent percutaneous placement of the Vena Tech filter at the authors' institution. Follow-up has been obtained to evaluate the filter with regard to the prevention of pulmonary embolism, the maintenance of caval patency, and mechanical stability. Two cases of pulmonary embolism have been seen following filter placement. Three cases of caval thrombosis have occurred, with recanalization of the cava seen in two of these cases. There have been one broken filter and one case of incomplete filter opening. Limited filter tilting and migration have occurred, though in no case has filter tilt or migration been clinically significant. This experience with the Vena Tech filter suggests that it is safe and effective for the prevention of pulmonary embolism.

Adolescent↗
PubMed1991

[Effects of stimulation of locus coeruleus on cardiac contractility and renal nerve activity].

Experiments were performed on 64 cats anesthetized with chloralose-urethane, paralyzed and artificially ventilated. Electrical stimulation of locus coeruleus (LC) elicited increases in BP, HR, LVSP, dP/dt max and RNA. Buffer nerve section had no effect on the increase of these parameters, but could prolong the time of rise of BP and recovery phases. Injection of L-glutamate into LC, on the other hand, could decrease BP, HR, LVSP and dP/dt max. Intra-LC injection of kainic acid could also decrease BP. When the LC neurons showed degeneration or depolarization block after kainic acid injection, electrical stimulation of the LC could still elicit marked pressor response. The results suggest that the pressor response induced by electrical stimulation of LC might be mediated by the fibers passing through LC, while activation of LC neurons themselves would result in the depressor response.

Animals↗
PubMed1990

Evaluation of radiographs developed by a new ultrarapid film processing system.

The image quality of radiographs developed by a new ultrarapid processor was evaluated to determine if faster processing causes degradation in the image. The processor used was the Konica Super-Rapid SRX-501 model. Two films designed for this processor (Konica MGH-SR and MGL-SR) were processed in 45 sec and were compared with standard rapid processing in 90 sec of corresponding conventional films (Kodak TMG and OC). Rare-earth screens (Kodak Lanex Regular and Lanex Medium) used with the new and conventional films interleaved during angiographic studies or for phantom images were assessed for image quality. The basic imaging properties of the screen-film systems were examined by measuring (1) Hurter and Driffield curves, (2) modulation transfer functions by using the slit method, and (3) noise Wiener spectra. Subjective clinical assessment showed that the images obtained with ultrarapid processing were acceptable, with increased contrast and graininess. Hurter and Driffield curve measurements confirmed higher gradients. Modulation transfer function measurements were the same as for the conventional films. Noise Wiener spectrum measurements showed a 10% increase in noise for MGH-SR vs TMG film and a 30% increase for MGL-SR vs OC film. We conclude that acceptable image quality can be obtained using ultrarapid processing, with processing time approximately 60% that of conventional rapid processing. Potential applications include all areas in which rapid availability of the radiograph for interpretation is important. Although the processor studied was the first of its kind available, our evaluation indicates that the technology is available for a new class of ultrarapid processors.

Evaluation Studies as Topic↗
PubMed1990

[Frequency distribution of birth weight and gestational age in Taiwan].

Perinatal mortality rate is closely related to birth weight. We collected data on 35919 single liveborn babies at a teaching hospital in central Taiwan between 1977 and 1987, excluding 1980. The average birth weights of the two sexes combined, and of male and female live births separately, were 3163 +/- 486 gm, 3211 +/- 499 gm (N = 18865) and 3110 +/- 466 gm (N = 17054), respectively. The average gestational age of these live births was 39.7 +/- 2.1 weeks. The skewness and kurtosis of birth weight and gestational age distribution were -0.86 and 3.13, and -2.11 and 10.29, respectively. The two distributions indicated high kurtosis and left skewness, and were approximately normally distributed. Because birth weight and gestational age are highly associated, the skew-to-left residual distribution of birth weight might have been induced by low gestational age. Babies of low gestational age might not be able to develop mature organs and tissues, which, thus, results in high perinatal mortality. The distribution of birth weight intersects the normal curve within the region between 1500 gm and 2000 gm, which means that we may divide it into a predominant part and a residual part. Many articles have shown that the residual part is highly correlated to perinatal mortality rate and deserves further analysis. The average birth weight with gestational age at 40 weeks was 3239 +/- 385 gm, skewness and kurtosis were 0.16 and 0.75, respectively. The birth-weight distribution for a given number of gestational weeks is closer to the normal distribution. This paper provides standard figures and tables of birth weight with specific gestational age as a norm for related medical research.

Birth Weight↗
PubMed1989

Percutaneous transluminal angioplasty versus surgery for limb-threatening ischemia.

This retrospective study compared the results of percutaneous transluminal angioplasty (PTA) with those of infrainguinal bypass procedures in patients with critical arterial ischemia to determine which procedure had superior patency, limb salvage, and durability. The records of 54 patients who underwent 54 PTAs and 56 patients who underwent 63 infrainguinal bypasses (29 femoropopliteal and 34 femorodistal) from 1981 to 1987 were reviewed. In each patient PTA or bypass was the initial vascular procedure. Patients in both groups were comparable with respect to age, sex, and the presence of diabetes, hypertension, obesity, hypercholesterolemia, and smoking. Mean follow-up was 40 months (4 to 88 months) for the PTA group and 28 months (6 to 78 months) for the surgery group. Thirty-nine of the 54 patients (72%) were initially improved after PTA, whereas 15 patients (28%) showed no improvement. During follow-up, 20 initially successful PTAs reoccluded. Thirty-two of 54 patients (59%) underwent subsequent procedures, which included repeat PTA (10) and distal bypass (14). Patency determined by noninvasive Doppler studies was 18% at 2 years. Limb salvage, which included such secondary procedures, was 78%. Two-year patency for femoropopliteal bypasses was 68% with a limb salvage of 90%. Femorodistal bypasses had a 2-year patency of 47% and a limb salvage of 74%. No perioperative deaths occurred. Twenty-one of the 63 patients (33%) had subsequent procedures, which included thrombectomy (5) and bypass revision (9). In patients treated for limb-threatening ischemia the 2-year patency after femoropopliteal bypass (68%) or femorodistal bypass (47%) is significantly better than that from PTA (18%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1986

Increased collagenase activity in early aneurysmal dilatation.

Increased collagenase activity has been implicated as a basic abnormality in aortic aneurysm formation. We studied a localized aneurysmal change, poststenotic dilatation, and its relation to collagenase and elastase activity of the aortic wall. Cynomolgus monkeys underwent midthoracic aortic coarctation to produce poststenotic dilatation. Serial angiography showed that poststenotic dilatation was minimal or absent at 10 days, just discernible at 3 months, and prominent at 6 months. At the 3-month time interval, collagenase activity in the region of the poststenotic dilatation increased twofold compared with the same region in aortas from animals without poststenotic dilatation (p less than 0.05). There was no change in aortic elastase activity. These data indicate that collagenolysis and aneurysmal dilatation may be induced by local modifications of pressure and/or flow. Increased collagenase activity associated with abdominal aortic aneurysms may not represent an intrinsic metabolic defect but rather a response to altered hemodynamic conditions.

Animals↗
PubMed1979

Transcatheter bronchial brush and forceps biopsies. Histologic evaluation.

The histologic findings in transcatheter brush and forceps biopsies from 472 cases over a six-year period are evaluated. Diagnostic accuracy based on histologic findings was 38% and based on cytologic findings was 70%. When the two methods of examination were used, however, the overall accuracy was improved to 76%. In Hodgkin's disease and some inflammatory processes histologic examination is essential for the diagnosis. The transcatheter biopsies under fluoroscopic control are especially useful for securing tissues from the peripherally located lesions. When possible, examination of tissue obtained by transcatheter as well as forceps biopsies is encouraged.

Adenocarcinoma↗
PubMed1979

Retrograde brush biopsy of the ureter and renal pelvis.

In resonse to the limitations of urinary cytology which have resulted in a high incidence of false negative reports, a technique of retrograde brush biopsy has been developed. This technique aids in the diagnosis of carcinomas of the ureteral and renal collecting systems, thereby permitting earlier and more intensive treatment of malignant lesions of the urinary tract.

Biopsy↗
PubMed1977

Choledochal cyst in adults. A clinical and radiological study in ten cases.

Choledochal cysts are being recognized with an increasing frequency among the adult population. In this series a correct preoperative diagnosis was established in eight of the ten patients. The clinical tirad of obstructive jaundice, right upper abdominal pain, and a palpable flactuant mass was noted in only two cases but at least one of these symptoms was present in all patients. Acute pancreatitis, cholecystitis, and biliary calculi were the commonly associated findings. New etiologic and clinical concepts of choledochal cysts are reviewed and the spectrum of radiographic features in adults is presented.

Adolescent↗
PubMed1976

Evaluation of renal masses including retrograde renal brushing.

1. The evaluation of renal masses has become an increasingly important topic because of the increasing incidence of kidney cancer, the improved cure rate of renal carcinoma with the proper preoperative diagnosis, and the proliferation in renal mass diagnostic methodology. 2. A variety of benign entities can produce an abnormal renal mass with attendant difficulties in being distinguished from malignant neoplasms. Among these benign lesions are: simple renal cysts, polycystic kidneys, congenital variations in renal size and shape, segmental renal hypertrophy, renal infarcts, intrarenal hematomas, renal hamartomas, renal leiomyomas, renal adenomas, renal angiomas, renal fibrolipomatosis, hydronephrosis of a duplicated collecting system, renal abscesses, and xanthogranulomatous pyelonephritis. 3. Nephrotomography, nephrosonography (ultrasound), adrenalin renal arteriography, selective magnification renal arteriography, renal venography and cavography, lymphangiography, renal scintillation scanning, abnormal levels of enzymes in blood and urine, immunologic studies (circulating antibodies and tumor-associated antigens), percutaneous needle aspirations, and retrograde renal brushing have all increased the diagnostic accuracy of determining the etiology of renal masses. None of these diagnostic procedures is infallible. A judicious combination of procedures gives the most reliable diagnostic results. 4. A search continues for (a) chemical agent(s) or a chemical profile in the blood or urine which is (are) specific for renal carcinoma, but as yet this is an investigational area and not a practical clinical reality.

Diagnosis, Differential↗
PubMed1976

Comparative value of four methods of investigating the pancreas.

In a prospective study for the diagnosis of pancreatic cancer, ultrasonography, radionuclide scanning, selective arteriography, and endoscopic retrograde cholangiopancreatography (ERCP) were compared. Eighty-nine consecutive patients were investigated; 58 underwent laparotomy, and 36 were found to have periampullary cancer; seven had other malignant tumors within the abdomen, and nine had pancreatitis on biopsy. Five had other benign disease, and there was one negative laparotomy. Thirty-one patients who did not have laparotomy have shown no evidence of cancer at one year follow-up. Ultrasonography was found to be more reliable than scan or arteriography in the detection and diagnosis of a mass in the pancreas. ERCP achieved the highest rate of correct definitive diagnosis.

Angiography↗
PubMedDate not supplied

Vessel, plaque, and lumen morphology after transluminal balloon angioplasty. Quantitative study in distended human arteries.

We performed transluminal balloon angioplasty in 24 cadaver and nine amputated limb superficial femoral arteries under controlled experimental conditions. The cadaver arteries were excised, restored to in situ length, redistended, and maintained at 100 mm Hg intraluminal pressure at 37 degrees C throughout the angiographic and dilation procedure and during fixation. The amputated limb arteries were dilated and pressure perfusion-fixed after dilation. Quantitative analysis of cadaver vessels revealed that arteries with prominent atherosclerotic lesions had the same internal elastic lamina (IEL) circumference (15.6 +/- 1.0 mm) as those with little or no stenosis (16.8 +/- 0.5 mm) but lumen area (8.8 +/- 1.7 mm2) was markedly reduced compared to nonstenotic sites (20.0 +/- 1.9 mm2, p less than 0.01). Lesions occupied 49 +/- 6% of the area circumscribed by the IEL in cadaver arteries with prominent plaques. After dilatation, lumen areas at stenotic sites were enlarged 43% on histologic sections (12.6 +/- 1.8 mm2 vs 8.8 +/- 1.7 mm2, p less than 0.01) and 31% as determined by angiography (p less than 0.05) when compared to immediately adjacent nondilated regions. The increased lumen area was associated with splitting of the intima near the edges of the plaque, separation of the edges of the plaque from the media, and stretching of the media and adventitia, often with accompanying rupture of the media. There was no evidence of plaque compression, fragmentation, deformation, modeling, or herniation into the media. The detached wedge-shaped edges of the lesions formed flaps projecting into the lumen, resulting in a marked increase in lumen irregularity on cross-section.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗