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.     

Regulation of human natural killer (NK) cell function: Induction of killing of an NK-resistant renal carcinoma cell line

Natural killer (NK)-like activity against a renal carcinoma cell line, Cur, was assessed. There was no spontaneous killing of Cur cells by human peripheral blood mononuclear cells in 4-hr assays. Cur killing was observed in 18-hr assays, but the magnitude of killing was variable and always markedly less than that against K562. Cur killing was mediated by a nonadherent, nonphagocytic lymphocyte, the activity of which could be modulated both positively and negatively by monocytes or their products. Preincubation of effectors with monocyte supernatant, interleukin 1 (IL-1), -interferon (IFN), or interleukin 2 (IL-2) greatly increased the magnitude of Cur killing and accelerated the kinetics of lysis. The addition of prostaglandin E₂ (PGE₂) duringin vitro activation of NK by IL-2 profoundly inhibited subsequent Cur lysis, whereas only minimal inhibition of K562 lysis was noted. However, following activation with IL-2, lysis of Cur targets was less sensitive to the inhibitory effects of PGE₂. Removal of Leu 11b(+), OKM1(+), orl-leucylleucine methyl ester-sensitive cells markedly decreased both Cur and K562 lysis. Moreover, CD16(+) cells purified with the fluorescence-activated cell sorter were found to mediate Cur killing. Whereas Cur and K562 lysis is mediated by phenotypically similar effector cells, the present studies demonstrate that the cytotoxic functions defined by the ability to lyse these two targets differ in response to a variety of immunoregulatory stimuli.     

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.     

Umbilical cord blood screening for cytomegalovirus DNA by quantitative PCR.

BACKGROUND: Cytomegalovirus (CMV) infection, which is the most common congenitally transmitted infection, affects approximately 1% of neonates worldwide. Despite its prevalence, no convenient screening test for neonatal CMV infection has been implemented. OBJECTIVE: The purpose of this pilot study was to evaluate the feasibility and yield of screening umbilical cord blood for CMV DNA emiaby quantitative PCR. STUDY DESIGN: Umbilical cord blood was tested for CMV DNAemia using a commercial quantitative PCR assay. Maternal CMV serostatus at the time of delivery was assessed by testing for CMV IgG and IgM antibodies in serum. CONCLUSIONS: Screening for congenital CMV infection with PCR is easily incorporated into routine labor and delivery care using discarded cord blood specimens to identify neonates whose infection is otherwise undiagnosed. Among 433 infants tested, two (0.5%) had DNAemia detected in cord blood, one of whom was symptomatic, and both of whose mothers were CMV IgG positive and IgM negative. Viremic neonates identified by screening with PCR may be at high risk of developing long-term neurological complications of CMV infection and cannot reliably be identified using clinical presentation or maternal serology. Because of its convenience, cord blood CMV screening with PCR should be further investigated for incorporation into neonatal screening protocols.     

Brain regions and their dynamics in prospective memory retrieval: a MEG study.

We measured brain activity using magnetoencephalography in five participants during ongoing tasks that included prospective memory, retrospective memory, and oddball trials. Sources were identified in the hippocampal formation and posterior parietal and frontal lobes. Posterior parietal cortex activation had an earlier onset in the prospective memory condition than retrospective memory or oddball conditions, a higher level of theta activity in the retrospective condition, and higher levels of upper alpha in the prospective and oddball conditions. Activation of the hippocampal formation had a longer duration in the retrospective memory and prospective memory conditions than the oddball condition, but prominent alpha and theta band activity was present in all three conditions. We interpret the early (87 ms) onset of activity in parietal cortex as evidence for an initial noticing of appropriate conditions for a PM response. Hippocampal activity may reflect a subsequent memory search for the intended action.     

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.     

Filling the gaps in physician communication. The role of the Internet among primary care patients

BACKGROUND: Millions of people use the Internet as a source for health information yet little is understood about how the use of the Internet for health information is related to the doctor-patient relationship. OBJECTIVE: We conducted the present study to understand the association between one's interest in using the Internet for general and quality-oriented health information and attitudes about one's communications with health care provider(s). DESIGN: Cross-sectional survey. SETTING: Four community-based primary care practices in Rhode Island. MEASUREMENTS: A single self-administered survey included items to measure: interest in using the Internet to look for general and quality-oriented information and a patient's perceptions of the degree to which their doctors over the previous year have: (1) given them information and (2) engaged them in the decision-making process. RESULTS: A total of 300 patients completed the survey. Among patients without Internet access, interest in using the Internet for health related activities was less among patients who felt that their doctor gave less information: Odds ratio 0.83 (95% CI, 0.70-0.98) and greater among patients who felt that their doctor engaged them more in decision making: Odds ratio 1.3 (95% CI, 1.1-1.6). Among patients with Internet access, we found no relationship between interest in using the Internet for health related activities and measures of patient-physician communication or patient-physician decision making. CONCLUSIONS: Interest in using the Internet for health information is greater for those who (1) felt their doctors provided less information and (2) felt their doctors engaged them more in the decision-making process, but this is true only for those without access to the Internet.     

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.     

Effects of Feeding Time on Markers of Muscle Metabolic Flexibility Following Acute Aerobic Exercise in Trained Mice Undergoing Time Restricted Feeding

Time-restricted feeding (TRF) is becoming a popular way of eating in physically active populations, despite a lack of research on metabolic and performance outcomes as they relate to the timing of food consumption in relation to the time of exercise. The purpose of this study was to determine if the timing of feeding/fasting after exercise training differently affects muscle metabolic flexibility and response to an acute bout of exercise. Male C57BL/6 mice were randomized to one of three groups for 8 weeks. The control had ad libitum access to food before and after exercise training. TRF-immediate had immediate access to food for 6 h following exercise training and the TRF-delayed group had access to food 5-h post exercise for 6 h. The timing of fasting did not impact performance in a run to fatigue despite TRF groups having lower hindlimb muscle mass. TRF-delayed had lower levels of muscle HSL mRNA expression and lower levels of PGC-1α expression but displayed no changes in electron transport chain enzymes. These results suggest that in young populations consuming a healthy diet and exercising, the timing of fasting may not substantially impact metabolic flexibility and running performance.