Molecular mechanisms for the hypoxia-dependent activation of 3-amino-1,2,4-benzotriazine-1,4-dioxide (SR 4233)

The reduction of the hypoxic cell toxin 3-amino-1,2,4-benzotriazine-1,4-dioxide (SR 4233) was investigated using pulse radiolysis, radiation chemical reduction, and xanthine oxidase. Evidence was found that the one-electron reduction product of the parent compound is an oxidizing radical that caused single- and double-strand breaks in plasmid DNA and that produced a malondialdehyde-like thiobarbituric acid adduct from 2-deoxy-D-ribose. Possible forms of the reactive radical, either carbon- or nitrogen-centered, are suggested. The "natural" lifetime of the radical was sufficiently long that it could diffuse over significant distances within hypoxic cells and thus inflict oxidative damage on cellular targets. The radical reacted with O2 at a rate comparable to those of the nitroimidazoles misonidazole and metronidazole. Thus, the selectivity for hypoxic cells is probably due to the elimination of "futile" reduction when the cellular oxygen concentration is sufficiently low.     

Changes in Skeletal Microstructure Through Four Continuous Years of rhPTH(1–84) Therapy in Hypoparathyroidism

Bone remodeling is reduced in hypoparathyroidism, resulting in increased areal bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) and abnormal skeletal indices by transiliac bone biopsy. We have now studied skeletal microstructure by high-resolution peripheral quantitative computed tomography (HR-pQCT) through 4 years of treatment with recombinant human PTH(1–84) (rhPTH[1–84]) in 33 patients with hypoparathyroidism (19 with postsurgical disease, 14 idiopathic). We calculated Z-scores for our cohort compared with previously published normative values. We report results at baseline and 1, 2, and 4 years of continuous therapy with rhPTH(1–84). The majority of patients (62%) took rhPTH(1–84) 100 μg every other day for the majority of the 4 years. At 48 months, areal bone density increased at the lumbar spine (+4.9% ± 0.9%) and femoral neck (+2.4% ± 0.9%), with declines at the total hip (−2.3% ± 0.8%) and ultradistal radius (−2.1% ± 0.7%) (p < .05 for all). By HR-pQCT, at the radius site, very similar to the ultradistal DXA site, total volumetric BMD declined from baseline but remained above normative values at 48 months (Z-score + 0.56). Cortical volumetric BMD was lower than normative controls at baseline at the radius and tibia (Z-scores −1.28 and − 1.69, respectively) and further declined at 48 months (−2.13 and − 2.56, respectively). Cortical porosity was higher than normative controls at baseline at the tibia (Z-score + 0.72) and increased through 48 months of therapy at both sites (Z-scores +1.80 and + 1.40, respectively). Failure load declined from baseline at both the radius and tibia, although remained higher than normative controls at 48 months (Z-scores +1.71 and + 1.17, respectively). This is the first report of noninvasive high-resolution imaging in a cohort of hypoparathyroid patients treated with any PTH therapy for this length of time. The results give insights into the effects of long-term rhPTH(1–84) in hypoparathyroidism. © 2020 American Society for Bone and Mineral Research.     

ImmPort: disseminating data to the public for the future of immunology

The immunology database and analysis portal (ImmPort) system is the archival repository and dissemination vehicle for clinical and molecular datasets created by research consortia funded by the National Institute of Allergy and Infectious Diseases Division of Allergy, Immunology, and Transplantation. With nearly 100 datasets now publicly available and hundreds of downloads per month, ImmPort is an important source for raw data and protocols from clinical trials, mechanistic studies, and novel methods for cellular and molecular measurements. To facilitate data transfer, templates for data representation and standard operating procedures have also been created and are also publicly available. ImmPort facilitates transparency and reproducibility in immunology research, serves as an important resource for education, and enables newly generated hypotheses and data-driven science.     

Morbidity after procurement of radial arteries in diabetic patients and the elderly undergoing coronary revascularization

BACKGROUND: The use of radial arteries for coronary revascularization is increasing. There remain concerns regarding alteration of upper extremity function after radial artery procurement. This study evaluates the functional morbidity in higher risk patients. METHODS: Between April 1997 and September 1999, 374 patients underwent unilateral or bilateral radial artery procurement. A questionnaire was used to evaluate symptoms related to motor and sensory function and changes in appearance after radial artery harvest. RESULTS: Two hundred eighty-nine patients were successfully interviewed. The average age was 63 years. Median follow-up was 9.5 months (range, 2 to 23 months). No patient suffered limb loss. Altered gross and fine motor function, residual pain, paresthesias, numbness, pallor, swelling, and altered temperature sensation were compared among diabetic patients, patients older than 70 years, and patients without these characteristics. CONCLUSIONS: Radial artery procurement for elective coronary revascularization can be done with minimal serious morbidity in higher risk patients. The most common symptoms were numbness and paresthesia. Despite the finding of greater residual pain in diabetic patients, we do not believe the use of radial artery conduits is contraindicated in these patients.     

Deficient activation by a human cell strain leads to mitomycin resistance under aerobic but not hypoxic conditions

Two non-transformed human skin fibroblast strains, GM38 and 3437T, were found to be more sensitive to the bioreductive alkylating agents mitomycin C (MMC) and porfiromycin (PM) under hypoxic compared to aerobic conditions. One of these strains, 3437T, was 6-7 times more resistant to these agents under aerobic exposure conditions, but was identical in sensitivity to the normal strain, GM38, under hypoxic conditions. Aerobic 3437T cells demonstrated no increased resistance to cisplatin compared to the normal strain, arguing against enhanced ability to repair DNA interstrand cross-links as the underlying explanation for the mitomycin resistance. The aerobic resistance of 3437T was not altered by dicumarol, an inhibitor of the enzyme DT-diaphorase which is believed to be involved in aerobic activation of MMC and PM. Dicumarol did increase the resistance of GM38, but not to the same level of resistance demonstrated by 3437T. These results suggest that the aerobic MMC and PM resistance of 3437T may arise, in part, from a deficiency in DT-diaphorase activity. The identical sensitivities under hypoxic conditions indicate that drug activation pathways operative in the absence of oxygen are similar in both the normal and 3437T cells.     

Schädigung der vegetativen Hirnzentren durch Kopftrauma

Ohne Zusammenfassung     

Modification of the cytotoxic activity of mitomycin C by oxygen and ascorbic acid in Chinese hamster ovary cells and a repair-deficient mutant

The cellular and molecular damage produced by mitomycin C (MMC) in Chinese hamster ovary cells, AA8-4, and a repair deficient mutant of this line, UV-20, was studied by utilizing a system in which oxygen levels could be altered and monitored in solution during acute drug exposures. The cytotoxic activity of MMC decreased from hypoxic conditions to 1% oxygen in solution, while from 1 to 20% there was little change. The relative level of DNA cross-linking in cells was examined under these conditions by alkaline elution and found to increase as cell survival decreased. Utilizing a cell-free assay which detects formation of alkylating species it was confirmed that, while alkylation was observed under aerobic conditions, overall levels increased in the absence of oxygen. The presence of ascorbic acid in the exposure medium (0.284 mM) increased the aerobic but not the hypoxic cytotoxicity of MMC. This resulted in a diminished differential toxicity for cells exposed under aerobic versus hypoxic conditions in the presence of ascorbic acid. When ascorbic acid was present, net alkylation increased under aerobic conditions but was unchanged under hypoxic conditions. One interpretation of these results is that at least two mechanisms of activation of MMC to toxic intermediates may be present in these cells.     

Molecular interactions, internal structure and drug release kinetics of rationally developed polymer–lipid hybrid nanoparticles

This paper presents the first study of molecular interactions of ingredients and internal nanostructure in relation to drug loading and release mechanisms/kinetics of rationally designed solid polymer–lipid hybrid nanoparticles (PLN). The PLN were prepared by using a rationally selected composition that was found in our previous work to provide optimized interactions of verapamil hydrochloride (VRP) with dextran sulfate sodium (DS) and then the VRP–DS complex with dodecanoic acid (DA). The solid-state properties of the components, their molecular interactions and the morphology, particle size and internal structure of PLN were determined by use of differential scanning calorimetry, powder X-ray diffraction, ¹³C nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering. The distribution of VRP in PLN was examined by TEM imaging using a cationic gold tracer. Drug release studies were conducted in various media. Drug loading as high as 36% and loading efficiencies up to 99% were achieved in the rationally formulated PLN. Hydrogen bonding between drug, polymer and lipid and a uniform distribution of amorphous VRP within the solid lipid matrix were evident. Sustained drug release from the PLN was mainly controlled by ion exchange and diffusion processes. The results demonstrated that strong molecular interactions among the drug, the polymer and the lipid in the optimized formulation were responsible for the improved drug loading and release performance of the PLN.