Elemental composition of human semen is associated with motility and genomic sperm defects among older men.

BACKGROUND: Older men tend to have poorer semen quality and are generally at higher risks for infertility and abnormal reproductive outcomes. METHODS: We employed proton-induced X-ray emission (PIXE, 3 MeV proton beam) to investigate the concentrations of zinc, copper, calcium, sulfur, chlorine, potassium, titanium, iron and nickel in washed sperm and seminal plasma from non-smoking groups of 10 older men (65-80 years old) and 10 younger men (22-28 years old) who were concurrently assayed for sperm function and genomicly defective sperm. RESULTS: The older group showed elevated zinc, copper and calcium in sperm and elevated sulfur in seminal plasma compared with the younger men. The older group also showed reduced motility as well as increased sperm DNA fragmentation, achondroplasia mutations, DNA strand breaks and chromosomal aberrations. Sperm calcium and copper were positively associated with sperm DNA fragmentation (P < 0.03). Seminal sulfur was positively associated with sperm DNA fragmentation and chromosomal aberrations (P < 0.04), and negatively associated with sperm motility (P < 0.05). Sperm calcium was negatively associated with sperm motility, independent of male age (P = 0.01). CONCLUSIONS: We identified major differences in elemental concentrations between sperm and seminal plasma and that higher sperm copper, sulfur and calcium are quantitatively associated with poorer semen quality and increased frequencies of genomic sperm defects.

Assessment of proton microbeam analysis of 11B for quantitative microdistribution analysis of boronated neutron capture agents in biological tissues.

The (11)B(p,alpha)(8)Be* nuclear reaction was assessed for its ability to quantitatively map the in vivo subcellular distribution of boron within gliosarcomas treated with a boronated neutron capture therapy agent. Intracranial 9L gliosarcomas were produced in Fischer 344 rats. Fourteen days later, the majority of the rats were treated with f-boronophenylalanine and killed humanely 30 or 180 min after intravenous injection. Freeze-dried tumor cryosections were imaged using the (11)B(p,alpha)(8)Be* nuclear reaction and proton microbeams obtained from the nuclear microprobe at Lawrence Livermore National Laboratory. The (11)B distributions within cells could be imaged quantitatively with spatial resolutions down to 1.5 microm, minimum detection limits of 0.8 mg/kg, and acquisition times of several hours. These capabilities offer advantages over alpha-particle track autoradiography, electron energy loss spectroscopy, and secondary ion mass spectrometry (SIMS) for quantification of (11)B in tissues. However, the spatial resolution, multi-isotope capability, and analysis times achieved with SIMS are superior to those achieved with (11)B(p,alpha)(8)Be* analysis. When accuracy in quantification is crucial, the (11)B(p,alpha)(8)Be* reaction is well suited for assessing the microdistribution of (11)B. Otherwise, SIMS may well be better suited to image the microdistribution of boron associated with neutron capture therapy agents in biological tissues.

Characterization of clay-based enterosorbents for the prevention of aflatoxicosis.

Appropriate chemical interventions that can block, retard, or significantly diminish foodborne exposure to aflatoxins are high priorities. A practical and effective approach to the aflatoxin problem has been the dietary inclusion of a processed calcium montmorillonite clay (HSCAS). HSCAS acts as an enterosorbent that rapidly and preferentially binds aflatoxins in the gastrointestinal tract resulting in decreased aflatoxin uptake and bioavailability. In mechanistic studies, we have shown that the intact dicarbonyl system in aflatoxin is essential for optimal sorption by HSCAS. Evidence also suggests that aflatoxins react at multiple sites on HSCAS clay surfaces (especially those within the interlayer region). Due to conceivable risks associated with the dietary inclusion of nonspecific binding agents, all aflatoxin enterosorbents should be tested in sensitive animal models for efficacy, safety, and the potential for nutrient interactions.

Steady-state asymmetric nanospray dual ion source for accurate mass determination within a chromatographic separation.

Here we report the design, implementation, and initial use of an asymmetric steady-state continuous dual-nanospray ion source. This new source design consists of two independently controlled and continuously operating nanospray interfaces with funnel shaped counter electrodes. A steady-state ion mixing region combines the ions from the two sources into a single ion beam in the intermediate region after ion extraction from the nanospray sources but before the bulk of the pressure gradient of the vacuum interface. With this design we have achieved robust mixing of ions with no loss of duty cycle and remarkable ionization characteristics that appear entirely noncompetitive and potentially beneficial. This allows continuous introduction of internal mass calibration ions during a liquid chromatography-mass spectrometric analysis. This in turn allows for recalibration of individual spectra yielding sub part per million mass accuracy throughout the run. The steady-state approach presented here has several advantages over previous approaches. Since neither the voltage nor positions of the sprayers are changed, the nanospray has greater spray stability. The ions produced by the analyte sprayer are continuously sampled, as opposed to time-sharing which necessitates that the analyte ion stream be interrupted for some part of the duty cycle. There are no moving parts, no rapid changes to high voltages requiring additional control electronics, and no need for completely separate vacuum interfaces and the associated complexity. The sprayers are independently controlled and do not exhibit competition or mutual ionization suppression. This novel source has been implemented with a Bruker Apex II 9.4 T FTICR with a modified Apollo electrospray ion source as part of a nanoflow liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometry analysis platform. Because of the low cost of implementation, the new source could potentially be applied to other forms of mass spectrometry, such as electrospray ionization-time-of-flight (ESI-TOF), which can benefit from internal mass calibration.

Elemental compositions of comet 81P/Wild 2 samples collected by Stardust.

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.

Alpha-particle energy loss measurement of microgram depositions of biomolecules.

A commercially available alpha-particle spectrometer and 210Po alpha-particle source were used to determine the mass of microgram quantities of biomolecules. Samples were deposited in microliter volumes on thin silicon nitride windows and dried. The energy loss of the alpha-particles after traversing the sample was converted to a mass using tabulated alpha-particle stopping powers. The measurement was absolute, independent of biomolecule species, and no standards were needed for quantitation. The method has a dynamic range of 0.1-100 microg for deposits of diameter 1-2 mm. The precision varies from approximately 20% at 100 ng to a few percent at 5-100 microg. The silicon nitride windows allow multimodal analysis of the same quantified sample, including PIXE probing of elemental abundances, molecular identification by mass spectrometry, and isotopic quantitation of interactions. The method was used with accelerator mass spectrometry to quantify specific activities of microgram quantities of 14C-labeled proteins.