Testing cord blood human chorionic gonadotropin as a surrogate marker for early identification of human immunodeficiency virus-1 infection in children

We measured human chorionic gonadotropin (hCG) in cord sera of 22 infants born to women infected with the human immunodeficiency virus-1 (HIV-1). hCG was also determined in cord sera from 173 infants born at a suburban hospital to HIV-1-seronegative women. The findings indicate that 16 (9%) of 173 HIV-1-seronegative samples had hCG levels greater than 90 IU/L (values were distributed as a Poisson curve). In contrast, 8 (36%) of the 22 infants born to HIV-1-infected women had hCG levels in excess of 90 IU/L, and 7 (88%) of these were shown to be HIV-infected. The remaining 14 infants born to HIV-1-infected women had low hCG levels, and 3 (21%) of the 14 had HIV infection. Mean follow-up time for HIV-uninfected infants was 17.5 months (range 9 months to 3 years). A statistically significant association between maternal-fetal HIV-1 transmission and hCG levels > or = 90 IU/L in cord sera was observed (p = 0.02). The difference between CD4 counts among mothers who transmitted HIV and those who did not was also statistically significant (p = 0.025). On the basis of this study's findings, we propose that cord blood hCG may serve as a surrogate marker for HIV-1 infection. Testing hCG levels in cord sera is an inexpensive and readily available screening test for early identification of infants at increased risk for getting HIV-1 from their mothers.     

Conditional-sampling spectrograph detection system for fluorescence measurements of individual airborne biological particles

We report the design and operation of a prototype conditional-sampling spectrograph detection system that can record the fluorescence spectra of individual, micrometer-sized aerosols as they traverse an intense 488-nm intracavity laser beam. The instrument's image-intensified CCD detector is gated by elastic scattering or by undispersed fluorescence from particles that enter the spectrograph's field of view. It records spectra only from particles with preselected scattering-fluorescence levels (a fiber-optic-photomultiplier subsystem provides the gating signal). This conditional-sampling procedure reduces data-handling rates and increases the signal-to-noise ratio by restricting the system's exposures to brief periods when aerosols traverse the beam. We demonstrate these advantages by reliably capturing spectra from individual fluorescent microspheres dispersed in an airstream. The conditional-sampling procedure also permits some discrimination among different types of particles, so that spectra may be recorded from the few interesting particles present in a cloud of background aerosol. We demonstrate such discrimination by measuring spectra from selected fluorescent microspheres in a mixture of two types of microspheres, and from bacterial spores in a mixture of spores and nonfluorescent kaolin particles.     

The effect of changes in nitrate concentration in drinking water on methemoglobin levels in infants

For a five‐day period infants consuming powdered milk formula made up with tap water were exposed to water of controlled nitrate content. There was a significant rise in MetHb levels above normal in most children after the first day of exposure to high nitrate water (108 mg/1 NO3). This was followed by some indication of a drop in MetHb levels despite the continued exposure and finally a return to normal levels when the exposure to nitrates stopped. No clinical signs of methemoglobinemia developed. The possible existence of an adaption mechanism is suggested but requires further elucidation.     

Fluorescence Particle Counter for Detecting Airborne Bacteria and Other Biological Particles

We have constructed a laser-based particle counter that detects the fluorescence, as well as the elastic scattering, from individual airborne particles as they traverse a laser beam. This fluorescence particle counter (FPC) can detect fluorescence from μm-sized Bacillus subtilis spore agglomerates when illuminated with intense light at 488 nm from an argon ion laser, either ～ 0.7 kW cm^?2 extracavity or ～ 50 kW cm^?2 intracavity. We suspect that flavins in the spores are the molecules primarily responsible for the fluorescence, because the peak fluorescence emission of the biological materials at this excitation wavelength is in the range 530–550 nm, which is characteristic of flavins. Fluorescence from kaolin, hematite, and polystyrene particles was not detectable; the lack of fluorescence indicates that the FPC may be able to differentiate between biological and nonbiological aerosols. The FPC samples aerosol-laden air at a rate of ～ 1 mL s^?1, and is capable of measuring aerosol concentrations up to several thousand per milliliter. The FPC may be helpful in detecting and characterizing airborne bacteria and other airborne particles of biological origin.     

Energy release rate calculations for an interface mode III edge crack based on a conservation integral

The M-integral is applied to the calculation of energy release races for interface edge cracks of the Mode III type. Specifically, for an edge crack along the interface between two elastic wedges of different opening angles and dissimilar elastic properties, and that is subjected to point loads at the apex, a relation is derived among the length of the crack, the energy release race of the crack, the applied loads, the wedge angles and the material parameters.     

Role of illness in producing learned taste aversions in rats: A comparison of several rodenticides.

Compared several toxic agents to test the effect of various types of illness in producing learned taste aversions. Ss in 2 experiments were 90 female and 26 male Sprague-Dawley rats. After a 10-min sucrose drinking trial, groups of Ss were injected ip with lithium chloride or with a strong, near lethal dose of a rodenticide. Strong sucrose aversions were acquired by groups injected with lithium chloride, copper sulfate, sodium fluoroacetate, or red squill, and very weak or no aversions were learned by groups injected with thallium, warfarin, cyanide or strychnine. Results are discussed in terms of onset of symptoms, duration of symptoms, and kinds of physiological effects necessary to produce aversions. It is concluded that the effects of different drugs may be mediated by different physiological systems in producing learned taste aversions. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pheromonotropic activity of naturally occurring pyrokinin insect neuropeptides (FXPRLamide) in Helicoverpa zea

Insect neuropeptides, having the common C-terminal sequence FXPRLamide X = V, T, S, or G), were tested for phyeromonotropic activity in the moth, Helicoverpa zea. Dose-response studies indicated that locustamyotropin-II or locustapyrokinin-II induced production of more pheromone than was stimulated by the pheromone biosynthesis activating neuropeptide of this moth. Other peptides showed various degrees of pheromonotropic activity. The data indicated that substitution of the variable amino acid in the C-terminal pentapeptide sequence resulted in significant differences in pheromonotropic activity. However, the overall structure of the peptide was also found to be of importance.     

Dynamic counterbalancing the single-piston linear compressor of a Stirling cryogenic cooler

Low vibration Stirling cryocoolers often rely on dual-piston linear compressors, the known disadvantages of which, as compared to their single-piston rivals, are: low reliability, increased power consumption, price, bulk, sensitivity to external vibration and g-forces. However, because of the inherently low level of vibration export, as required in numerous vibration sensitive electronic and electro-optic applications, the dual-piston approach has become prevalent in today’s industrial practice.The authors report on the novel approach to the passive control of a fundamental component of a vibration export from a single-piston compressor down to the levels typical for the actively controlled dual-piston rival. The technique relies on the newly proposed principle of dynamic counterbalancing, where an auxiliary movable mass is flexibly attached to a movable piston assembly and to the stationary compressor casing using auxiliary mechanical springs. The proper design of such a “spring-mass-spring” counterbalancer yields zero vibration export at minimum electrical power and current consumed by the motor.Based on the theoretical analysis, the design of the single-piston compressor of 1 W@77 K Ricor model K529N Stirling cryocooler was enhanced by adding such a counterbalancer. The obtained experimental results are in full agreement with the theoretical prediction. From experiment, the vibration export at driving frequency was reduced 57-fold at practically the same electrical current and power consumed by the compressor actuator as compared with the basic cooler.     

Prognostic significance of B-lineage leukemic cell growth in SCID mice: a Children's Cancer Group Study

Primary leukemic cells isolated from children (N = 681 ) with newly diagnosed B-lineage ALL enrolled on risk-adjusted treatment protocols of the Children's Cancer Group (CCG) were injected via the tail vein into 7-10 week old SCID mice. Leukemic cells from 104 of 681 patients (15.3%) were able to engraft and proliferate in one or more SCID mouse organs. These SCID+ patients were somewhat more likely than SCID patients to be older than 10 years of age (p = 0.03) and have WBC counts >20,000/microL (p = 0.04), but the groups were similar with respect to all other presenting features. Event-free survival (EFS) outcome at 3 years of follow-up was similar for SCID+ patients compared with SCID- patients (79.2%, SD = 5. 1% vs. 84.8%, SD = 2.8%; p = 0.20). Overall survival also was similar between the two groups (p = 0.93). This result was maintained within the subgroups of lower risk (N = 448) and higher risk (N = 233) patients. However, there were trends for poorer outcome among patients whose cells caused overt leukemia in SCID mice and infiltrated either 6 or more organs (p = 0.03), skeletal muscle (p = 0.0003), kidney (p = 0.05), or spleen (p = 0.06). Thus, engraftment of primary leukemic cells in SCID mice was not a significant predictor of outcome for the aggregate population of B-lineage ALL patients, the majority of whom were low risk, treated according to contemporary intensive chemotherapy programs of the CCG. However, development of disseminated overt leukemia and infiltration of SCID mouse skeletal muscle by primary leukemic cells from adjacent bone marrow may reflect a biologically more aggressive disease and identify patients at higher risk for treatment failure.