Diminished placental Factor XIIIA1 expression associates with pre-conception antiretroviral treatment and preterm birth in pregnant people living with HIV.

We previously showed a link between maternal vascular malperfusion and pre-term birth (PTB) in pregnant people living with HIV (PPLH) initiating antiretroviral treatment (ART) before pregnancy, indicating poor placental vascularisation. After measuring antenatal plasma angiogenic factors to seek mechanistic insights, low levels of plasma Factor XIIIA1 (FXIIIA1) and vascular-endothelial-growth-factor (VEGF) was significantly associated with PTB at the time closest to delivery (median 34 weeks) in PPLH initiating ART before pregnancy. Knowing that FXIIIA1 is crucial for haemostasis, angiogenesis, implantation and pregnancy maintenance and that expression is found on placental macrophages (Hofbauer cells), we examined placentae at delivery from matching participants who either initiating ART before pregnancy or during gestation.

Unifying considerations and evidence of macrophage activation mosaicism through human CSF1R and M1/M2 genes.

Addressing the mononuclear phagocyte system (MPS) and macrophage M1/M2 activation is important in diagnosing hematological disorders and inflammatory pathologies and designing therapeutic tools. CSF1R is a reliable marker to identify all circulating MPS cells and tissue macrophages in humans using a single surface protein. CSF1R permits the quantification and isolation of monocyte and dendritic cell (DC) subsets in conjunction with CD14, CD16, and CD1c and is stable across the lifespan and sexes in the absence of overt pathology.

AAPM Task Group 108: PET and PET/CT shielding requirements.

The shielding of positron emission tomography (PET) and PET/CT (computed tomography) facilities presents special challenges. The 0.511 MeV annihilation photons associated with positron decay are much higher energy than other diagnostic radiations.

Radiation protection standards: their evolution from science to philosophy.

The concept of applying constraints on individual sources to a small fraction of the public dose limit has been deemed inappropriate when shielding the medical X-ray sources. This represents a broad-based consensus of medical physics and radiological societies in the United States, and the report series on the shielding design for medical X-ray sources (including dental, X-ray imaging and therapeutic X ray) from the National Council on Radiation Protection and Measurements (NCRP) utilises 1 mSv y(-1) as a source control limit. In the present study, the rationale for such a conclusion is discussed, and a somewhat critical look at the current model of radiation protection of the public is made.

Radiation interactions and internal dosimetry in nuclear medicine.

The decay of a radioactive nucleus leads to the emission of energy in the form of photons or charged particles. The form and energy of the radiation emitted will depend on the decaying nucleus. Some of the emitted energy will be absorbed by target organs; the ratio of the absorbed energy to the mass of the target is the radiation dose.

Secondary shielding barriers for diagnostic x-ray facilities: scatter and leakage revisited.

Methods are presented for determining the thickness requirements for barriers against scatter and leakage radiation generated in a diagnostic x-ray facility. Equations are developed that express the shielded doses due to scatter and leakage with explicit dependence on the operating potential used in clinical settings. The 1972 scatter experiment of Trout and Kelley is revisited, with suggested values for the scatter fraction that are somewhat different from those used in Report Number 49 of the NCRP.

Primary shielding barriers for diagnostic x-ray facilities: a new model.

Traditional methods of diagnostic x-ray shielding design assume that the raw primary beam impinges directly on the structural barrier with attenuation by the patient and by the hardware in the x-ray beam (cassette, cassette holder, x-ray table) being ignored. Moreover, primary barrier calculations are done assuming a single, conservatively high value of the operating potential, rather than the lower kVp values more representative of clinical usage. This results in extreme conservatism, which is no longer defensible in light of the lowered dose limit to a member of the general public of 1 mSv y-1, which is equal in magnitude to natural background radiation (excluding radon).

Evaluation of NCRP Report No. 49 assumptions on workloads and use factors in diagnostic radiology facilities.

A survey of modern medical institutions has been performed to measure the workload and primary beam use factors used in diagnostic x-ray installations in comparison to those suggested in Report 49 of the NCRP. Seven types of radiology installations were investigated, namely general radiographic rooms, general fluoroscopic and radiographic rooms (fluoroscopic and radiographic tubes surveyed separately), chest radiographic rooms, mammographic suites, and cardiac and peripheral angiographic suites. The radiologic technique (kVp and mAs) for each exposure performed on a total of 2396 patients was recorded either manually or by a commercially-available invasive electronic sensing system.

Scatter radiation intensities about mammography units.

The intensity of scattered x rays about two clinically installed mammographic units was measured at 25, 30, and 35 kVp over a range of scattering angles. The scatter-to-primary ratio for backscattering is measured to be 4 to 7 times greater than that for 90 degrees scattering. The scatter fraction is the ratio of scatter dose at 1 m to primary dose at 1 m per primary x-ray field area.

Transmission data for shielding diagnostic x-ray facilities.

Recently published exposure transmission curves for broad diagnostic x-ray beams in lead, concrete, gypsum wallboard, steel, plate glass, and wood have been used to calculate the transmission in 5 kVp increments over the 25 to 35 kVp range for molybdenum-anode tubes and 50 to 150 kVp for tungsten-anode tubes. The data are fit to a three parameter model for ease in calculating the x-ray transmission with computers or calculators.

The spatial and energy dependence of bremsstrahlung production about beta point sources in H2O.

A Monte Carlo simulation was performed to characterize the spatial and energy distribution of bremsstrahlung radiation from beta point sources important to radioimmunotherapy (RIT). Using the EGS4 Monte Carlo code, the isotropic emission and transport of monoenergetic 0.1-, 0.

A unified approach to the optimization of brachytherapy and external beam dosimetry.

Semi-automated optimization of dose distributions is possible using techniques borrowed from imaging science. The ideal distribution of dose is first deconvolved by a convolution kernel yielding an ideal weighting distribution in the patient. The weighting distribution describes the total energy released per unit mass of the irradiated medium.

EGS4 Monte Carlo determination of the beta dose kernel in water.

The EGS4 Monte Carlo code has been used to simulate the emission and energy deposition in H2O about point sources of monoenergetic electrons and radionuclides of potential use in radioimmunotherapy. The radiations studied were 0.05, 0.

The axial ligands of heme in cytochromes: a near-infrared magnetic circular dichroism study of yeast cytochromes c, c1, and b and spinach cytochrome f.

Room temperature near-infrared magnetic circular dichroism and low-temperature electron paramagnetic resonance measurements have been used to characterize the ligands of the heme iron in mitochondrial cytochromes c, c1, and b and in cytochrome f of the photosynthetic electron transport chain. The MCD data show that methionine is the sixth ligand of the heme of oxidized yeast cytochrome c1; the identify of this residue is inferred to be the single conserved methionine identified from a partial alignment of the available cytochrome c1 amino acid sequences. A different residue, which is most likely lysine, is the sixth heme ligand in oxidized spinach cytochrome f.

Peripherally acting enkephalin analogues. 2. Polar tri- and tetrapeptides.

The design, synthesis, and biological activity of a series of D-Arg2-enkephalin-derived tetrapeptide amides and tripeptide aralkylamides are reported. These polar analogues were designed to be excluded from the central nervous system with their action thus limited to peripheral opioid receptors. The effects of the nature of the aromatic ring, aryl ring substitution, and aralkylamine chain length on activity were investigated; in a number of cases the N-terminal amino group of Tyr1 was converted to a guanidino group to further increase hydrophilicity.

Shielding requirements for constant-potential diagnostic x-ray beams determined by a Monte Carlo calculation.

A Monte Carlo calculation has been performed to determine the transmission of broad constant-potential x-ray beams through Pb, concrete, gypsum wallboard, steel and plate glass. The EGS4 code system was used with a simple broad-beam geometric model to generate exposure transmission curves for published 70, 100, 120 and 140-kVcp x-ray spectra. These curves are compared to measured three-phase generated x-ray transmission data in the literature and found to be reasonable.

Peripherally acting enkephalin analogues. 1. Polar pentapeptides.

The design, synthesis, and biological activity of a series of highly polar enkephalin-related pentapeptides are reported. These analogues incorporate structural features that exclude them from the central nervous system and thereby restrict their action to peripherally located receptors. Hydrophilic analogues were obtained by introduction of polar D-amino acid residues at position 2 and, in certain cases, by conversion of the N-terminal amino group of the Tyr residue to a guanidino function.

Antibodies to interleukin-1 raised with synthetic peptides: identification of external sites and analysis of interleukin-1 synthesis in stimulated human peripheral blood monocytes.

Rabbit antibodies against peptides corresponding to amino acids 1-18, 45-65 and 71-90 of mature human interleukin-1 beta (IL-1 beta) precipitated 125I-labelled IL-1 beta, showing that these sites are accessible to antibody and located externally. Immunoprecipitation of 35S-methionine-labelled LPS-stimulated human peripheral blood monocytes followed by SDS-PAGE revealed the expected major bands of molecular weights 35,000 and 17,500. The 35,000 protein was found in the cell lysate and extracellularly in the medium, but the 17,500 protein was exclusively in the medium.