The development of harmonic distortion in pulsed finite-amplitude ultrasound passing through liver

The progressive development of finite-amplitude distortion of ultrasonic pulses has been investigated in excised bovine liver using pulsed focused ultrasonic beams at nominal frequencies of 2.5 and 3.5 MHz. Both the transducers and the powers used were those which may be encountered with clinical imaging equipment. Significant distortion of the waveform was observed to occur, particularly at higher powers. For example, at 2.5 MHz, with a mean input pressure (p0) of 0.58 MPa, the second harmonic in the pulse spectrum showed a maximum value of 10.5 dB below the fundamental and the highest third harmonic component was 19 dB below the fundamental. These particular observations illustrate that finite-amplitude distortion may be of considerable significance in the transmission through tissue of ultrasonic pulses during diagnostic scanning.     

Autofluorescent particles of human uterine muscle cells

Smooth muscle tissue collected from the uterine fundus of 24 patients undergoing hysterectomy was examined for chromolipoid pigments by histochemical and electron microscopic techniques. Certain cytoplasmic particles were found, mainly in smooth muscle cells, which exhibited characteristic autofluorescence, sudanophilia, and acid phosphatase activity but did not correspond to any typical pigment described previously. These particles were present in all subjects and they tended to increase in number with age. Chemical tests on tissue lipid extracts failed to prove that vitamin A was responsible for the fluorescence. The ultrastructural appearance of the particles somewhat variable, but most particles were rounded and of low electron density, with a lucent central space and dense bodies, probably lysosomes, at the periphery. The whole complex was enclosed by a single trilaminar membrane.     

Immunoassays and nucleic acid detection with a biosensor based on surface plasmon resonance

A technique based on surface plasmon resonance is described which can be used to detect changes of refractive index that occur when one partner of a molecular binding pair diffuses from solution to bind the other partner which is immobilised on a silver surface. Results for the molecular binding pairs; protein-antibody, hapten-antibody and DNA-DNA are described. Instrumentation necessary for implementation of the technique is detailed. Immunoassay of proteins and haptens is possible in less than one minute with a sensitivity of 10(-9) mol/l. Hybridisation of 10 fmoles of a 97 base target sequence on the 1 mm2 area of detection to an immobilised oligonucleotide probe can be detected in less than five minutes. Advantages of the technique include the ability to record the kinetics of binding reactions in "real time" and the lack of labels in this simple assay format. Methods of improving the sensitivity are discussed.     

The new HLA.

The application of molecular genetics and biochemical techniques to the study of the HLA system over the past few years has resulted in tremendous advances in our knowledge of this area of the human genome. In this article, we describe the "new HLA" that has been pieced together recently through the combined efforts of molecular geneticists, biochemists, and HLA serologists, as well as developments in attempts to elucidate the associations of HLA antigens and disease.     

Nongerminomatous malignant germ cell tumors in children. A review of 89 cases from the Pediatric Oncology Group, 1971-1984

Clinical and morphologic features of 89 cases of childhood yolk sac tumor (YS) and embryonal carcinoma (EC) (29 associated with teratomas) submitted to the Rare Tumor Registry of the Southwest Oncology Group (1971-1979) or the Pediatric Oncology Group (1980-1984) between 1971 and 1984 were reviewed and submitted to statistical analysis. This review showed an improved survival for each 5-year period regardless of tumor site, no statistically significant difference between "pure" tumors and those mixed with other teratomatous components, no statistically significant difference between YS and EC in children, a better than reported prognosis for sacrococcygeal tumors occurring after the neonatal period, a particularly poor prognosis for neonatal "benign" sacrococcygeal teratomas resected without coccygectomy when they recur as YS, excellent survival for all testicular tumors regardless of age or the presence of EC, and the occurrence of mediastinal tumors in females.     

Long-term Impacts and Benefit–Cost Analysis of the Communities That Care Prevention System at Age 23, 12 Years After Baseline

Prevention Science - This study estimated sustained impacts and long-term benefits and costs of the Communities That Care (CTC) prevention system, implemented and evaluated in a longitudinal...     

Is diagnostic peritoneal lavage for blunt trauma obsolete?

Diagnostic peritoneal lavage was 97 percent accurate, with a 2 percent false positive rate and a 1 percent false negative rate in this series of 414 patients. The ease, safety, and accuracy of diagnostic peritoneal lavage justify its continued use in evaluating these patients. Recent studies show computerized tomography (CT) can be highly accurate in detecting intra-abdominal injuries after blunt trauma. We reviewed our experience with diagnostic peritoneal lavage (DPL) to evaluate whether the accuracy, safety, speed, and cost justified its continued use. Four hundred fifteen DPLs were performed on 414 patients from February 1, 1983, through December 31, 1987. All DPLs were done by the open technique. The lavage was considered grossly positive if 10 cc gross blood were aspirated. If there were greater than 100,000 red blood cells (RBC)/mm3, greater than 500 white blood cells (WBC)/mm3, elevated amylase or bilirubin, or bacteria or vegetable fibers the lavage was microscopically positive. There were no cases with elevated bilirubin, amylase, or presence of bacteria. All four cases with "rare vegetable fibers" were false positive. Six DPLs were for penetrating trauma to the lower chest or back. There were 291 negative lavages, including five false negatives (1%), and 124 positive DPLs, including seven false positives (2%), resulting in a crude accuracy of 97 percent. Three of the five false negative lavages had a ruptured diaphragm as the only intra-abdominal injury. There was one minor complication. DPL was usually performed in the trauma resuscitation room during the secondary survey. At our institution, the total fees for DPL are +185 less than the fees for CT. DPL is accurate, rapid, safe, and avoids the disruption of patient care that results in the radiology suite. DPL remains our procedure of choice for evaluating blunt abdominal trauma in the adult.