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Magnetotactic bacteria are envisaged as potential theranostic agents. Their internal magnetic compass, chemical environment specificity and natural motility enable these microorganisms to behave as nanorobots, as they can be tracked and guided towards specific regions in the body and activated to generate a therapeutic response. Here we provide additional diagnostic functionalities to magnetotactic bacteria Magnetospirillum gryphiswaldense MSR-1 while retaining their intrinsic capabilities. These additional functionalities are achieved by incorporating Tb or Gd in the bacteria by culturing them in Tb/Gd supplemented media. The incorporation of Tb provides luminescence properties, enabling potential applications of bacteria as biomarkers. The incorporation of Gd turns bacteria into dual contrast agents for magnetic resonance imaging, since Gd adds T 1 contrast to the existing T 2 contrast of unmodified bacteria. Given their potential clinical applications, the diagnostic ability of the modified MSR-1 has been successfully tested in vitro in two cell models, confirming their suitability as fluorescent markers (Tb-MSR-1) and dual contrast agents for MRI (Gd-MSR-1)., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

Magnetotactic bacteria Magnetospirillum magneticum AMB-1 have been cultured using three different media: magnetic spirillum growth medium with Wolfe's mineral solution (MSGM + W), magnetic spirillum growth medium without Wolfe's mineral solution (MSGM - W), and flask standard medium (FSM). The influence of the culture medium on the structural, morphological, and magnetic characteristics of the magnetosome chains biosynthesized by these bacteria has been investigated by using transmission electron microscopy, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism. All bacteria exhibit similar average size for magnetosomes, 40-45 nm, but FSM bacteria present slightly longer subchains. In MSGM + W bacteria, Co 2+ ions present in the medium substitute Fe 2+ ions in octahedral positions with a total Co doping around 4-5%. In addition, the magnetic response of these bacteria has been thoroughly studied as functions of both the temperature and the applied magnetic field. While MSGM - W and FSM bacteria exhibit similar magnetic behavior, in the case of MSGM + W, the incorporation of the Co ions affects the magnetic response, in particular suppressing the Verwey (∼105 K) and low temperature (∼40 K) transitions and increasing the coercivity and remanence. Moreover, simulations based on a Stoner-Wolhfarth model have allowed us to reproduce the experimentally obtained magnetization versus magnetic field loops, revealing clear changes in different anisotropy contributions for these bacteria depending on the employed culture medium. Finally, we have related how these magnetic changes affect their heating efficiency by using AC magnetometric measurements. The obtained AC hysteresis loops, measured with an AC magnetic field amplitude of up to 90 mT and a frequency, f , of 149 kHz, reveal the influence of the culture medium on the heating properties of these bacteria: below 35 mT, MSGM - W bacteria are the best heating mediators, but above 60 mT, FSM and MSGM + W bacteria give the best heating results, reaching a maximum heating efficiency or specific absorption rate (SAR) of SAR/ f ≈ 12 W g -1 kHz -1 .

Over the past few years, the use of nanomagnets in biomedical applications has increased. Among others, magnetic nanostructures can be used as diagnostic and therapeutic agents in cardiovascular diseases, to locally destroy cancer cells, to deliver drugs at specific positions, and to guide (and track) stem cells to damaged body locations in regenerative medicine and tissue engineering. All these applications rely on the magnetic properties of the nanomagnets which are mostly determined by their magnetic anisotropy. Despite its importance, the magnetic anisotropy of the individual magnetic nanostructures is unknown. Currently available magnetic sensitive microscopic methods are either limited in spatial resolution or in magnetic field strength or, more relevant, do not allow one to measure magnetic signals of nanomagnets embedded in biological systems. Hence, the use of nanomagnets in biomedical applications must rely on mean values obtained after averaging samples containing thousands of dissimilar entities. Here we present a hybrid experimental/theoretical method capable of working out the magnetic anisotropy constant and the magnetic easy axis of individual magnetic nanostructures embedded in biological systems. The method combines scanning transmission X-ray microscopy using an axi-asymmetric magnetic field with theoretical simulations based on the Stoner-Wohlfarth model. The validity of the method is demonstrated by determining the magnetic anisotropy constant and magnetic easy axis direction of 15 intracellular magnetite nanoparticles (50 nm in size) biosynthesized inside a magnetotactic bacterium.

Shape anisotropy is of primary importance to understand the magnetic behavior of nanoparticles, but a rigorous analysis in polyhedral morphologies is missing. In this work, a model based on finite element techniques has been developed to calculate the shape anisotropy energy landscape for cubic, octahedral, and truncated-octahedral morphologies. In all cases, a cubic shape anisotropy is found that evolves to quasi-uniaxial anisotropy when the nanoparticle is elongated ≥2%. This model is tested on magnetosomes, ∼45 nm truncated octahedral magnetite nanoparticles forming a chain inside Magnetospirillum gryphiswaldense MSR-1 bacteria. This chain presents a slightly bent helical configuration due to a 20° tilting of the magnetic moment of each magnetosome out of chain axis. Electron cryotomography images reveal that these magnetosomes are not ideal truncated-octahedrons but present ≈7.5% extrusion of one of the {001} square faces and ≈10% extrusion of an adjacent {111} hexagonal face. Our model shows that this deformation gives rise to a quasi-uniaxial shape anisotropy, a result of the combination of a uniaxial (Ksh-u = 7 kJ m-3) and a cubic (Ksh-c = 1.5 kJ m-3) contribution, which is responsible for the 20° tilting of the magnetic moment. Finally, our results have allowed us to accurately reproduce, within the framework of the Landau-Lifshitz-Gilbert model, the experimental AC loops measured for these magnetotactic bacteria.

Photogrammetry and cascading microscopy investigations of dental pulp specimens collected from 2,000-year-old individuals buried in a Roman necropolis in Besançon, France, revealed unprecedented preserved tissular and cellular morphology. Photogrammetry yielded 3-D images of the smallest archaeological human remains ever recovered. Optical microscopy examinations after standard haematoxylin-phloxine-saffron staining and anti-glycophorin A immunohistochemistry exposed dental pulp cells, in addition erythrocytes were visualised by electron microscopy, which indicated the ancient dental pulp trapped a blood drop. Fluorescence in situ hybridisation applied on red blood cells revealed the louse-borne pathogen Bartonella quintana, a finding confirmed by polymerase chain reaction assays. Through paleohistology and paleocytology, we demonstrate that the ancient dental pulp preserved intact blood cells at the time of the individual's death, offering an unprecedented opportunity to engage in direct and indirect tests to diagnose pathogens in ancient buried individuals.

Magnetotactic bacteria are aquatic microorganisms that internally biomineralize chains of magnetic nanoparticles (called magnetosomes) and use them as a compass. Here it is shown that magnetotactic bacteria of the strain Magnetospirillum gryphiswaldense present high potential as magnetic hyperthermia agents for cancer treatment. Their heating efficiency or specific absorption rate is determined using both calorimetric and AC magnetometry methods at different magnetic field amplitudes and frequencies. In addition, the effect of the alignment of the bacteria in the direction of the field during the hyperthermia experiments is also investigated. The experimental results demonstrate that the biological structure of the magnetosome chain of magnetotactic bacteria is perfect to enhance the hyperthermia efficiency. Furthermore, fluorescence and electron microscopy images show that these bacteria can be internalized by human lung carcinoma cells A549, and cytotoxicity studies reveal that they do not affect the viability or growth of the cancer cells. A preliminary in vitro hyperthermia study, working on clinical conditions, reveals that cancer cell proliferation is strongly affected by the hyperthermia treatment, making these bacteria promising candidates for biomedical applications., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Purpose: A phase I study was undertaken to determine the maximum-tolerated dose (MTD), principal toxicities, and pharmacokinetics of the novel topoisomerase I inhibitor irinotecan (CPT-11)., Patients and Methods: Sixty-four patients meeting standard phase I eligibility criteria were included (24 women, 40 men; median age, 51 years; primary sites: colon, head and neck, lung, pleura; 60 of 64 had been previously treated). Pharmacokinetics was determined by high-performance liquid chromatography (HPLC)., Results: One hundred ninety CPT-11 courses were administered as a 30-minute intravenous (IV) infusion every 3 weeks (100 to 750 mg/m2). Grade 3 to 4 nonhematologic toxicities included diarrhea (16%; three hospitalizations), nausea and vomiting (9%), asthenia (14%), alopecia (53%), elevation of hepatic transaminases (8%), and one case of skin toxicity. An acute cholinergic syndrome was observed during CPT-11 administration. Diarrhea appeared dose-limiting at 350 mg/m2, but this was circumvented by using a high-dose loperamide protocol that allowed dose escalation. Dose-dependent, reversible, noncumulative granulocytopenia was the dose-limiting toxicity (nadir, days 6 to 9; median recovery time, 5 days). Grade 3 to 4 anemia was observed in 9% of patients. One patient died during the study, 8 days after CPT-11 treatment. Two complete responses (cervix, 450 mg/m2; head and neck, 750 mg/m2) and six partial responses in fluorouracil (5-FU)-refractory colon cancer were observed (260 to 600 mg/m2). Pharmacokinetics of CPT-11 and active metabolite SN-38 were performed in 60 patients (94 courses). CPT-11 plasma disposition was bi- or triphasic, with a mean terminal half-life of 14.2 +/- 0.9 hours (mean +/- SEM). The mean volume of distribution (Vdss) was 157 +/- 8 L/m2, and total-body clearance was 15 +/- 1 L/m2/h. The CPT-11 area under the plasma concentration versus time curves (AUC) and SN-38 AUC increased linearly with dose. SN-38 plasma decay had an apparent half-life of 13.8 +/- 1.4 hours. Both CPT-11 and SN-38 AUCs correlated with nadir leukopenia and granulocytopenia, with grade 2 diarrhea, and with nausea and vomiting., Conclusion: The MTD of CPT-11 administered as a 30-minute IV infusion every 3 weeks is 600 mg/m2, with granulocytopenia being dose-limiting. At 350 mg/m2, diarrhea appeared dose-limiting, but high-dose loperamide reduced this toxicity and allowed dose escalation. For safety reasons, the recommended dose is presently 350 mg/m2 every 3 weeks; more experience must be gained to establish the feasibility of a higher dose in large multicentric phase II studies. However, when careful monitoring of gastrointestinal toxicities is possible, a higher dose of 500 mg/m2 could be recommended in good-risk patients. The activity of this agent in 5-FU-refractory colorectal carcinoma makes it unique and mandates expedited phase II testing.

Background: Diarrhea is a serious side effect that may prevent the administration of high doses of the antitumor drug Irinotecan (CPT-11)., Purpose: Intensive, high-dose loperamide was used in an attempt to control or downstage CPT-11-induced diarrhea and thus permit the use of higher dose intensities of CPT-11., Methods: Twenty-three patients with various cancers were treated with doses of CPT-11 ranging from 400 to 600 mg/m2, administered as a 30-minute intravenous infusion every 3 weeks. Starting 8 hours or more after the administration of CPT-11, any episode of diarrhea was treated with 2 mg of loperamide taken every 2 hours. Patients stopped taking loperamide only after a 12-hour diarrhea-free period. If diarrhea was not controlled after 3 consecutive days of nonstop loperamide intake, or if the patient was dehydrated, loperamide was stopped and the patient was hospitalized for intravenous fluids. If blood or mucus were found in the stools at any time during diarrhea, loperamide was stopped and the patient was hospitalized., Results: Seventeen of 23 patients had diarrhea while on CPT-11 treatment. Eighty-two CPT-11 cycles were administered to these 17 patients, and diarrhea occurred in 49 of these cycles, at a median time-to-onset of 6 days after CPT-11 administration. The loperamide protocol was followed in 46 of the 49 episodes of diarrhea, with 21 capsules of loperamide the median number being taken (range, 5-72). Only one patient was hospitalized for failure to respond to loperamide, and no major toxicity was associated with loperamide use. Fourteen of the 17 patients who experienced diarrhea were rechallenged with CPT-11 three or more times, and seven patients six or more times., Conclusions: High-dose loperamide controlled diarrhea in patients receiving CPT-11 and allowed administration of higher doses of CPT-11., Implications: The effectiveness of CPT-11 might be increased by higher dose intensities, which can be made tolerable by control of diarrhea with loperamide.

The clinical records of 26, predominantly male, adults with rhabdomyosarcomas in the head and neck were analyzed. Patients' ages ranged from 18 to 74 years (mean: 24.5 years). According to the retrospective clinical group classification, 18 (69%) of 26 were advanced tumors at initial presentation belonging to group III or IV. The ethmoids were the most common primary site of origin in 12 (46%) of 26 patients. Nodal and systemic metastases were noted in 12 (46%) and 6 (23%) patients, respectively. Bone metastases were noted in 4 patients. Heterogeneous treatment protocols were used with a variety of chemotherapy combinations in most cases, with surgery and radiotherapy. Overall results were poor, with a survival rate of 7.6% at 5 years. Neither histopathology nor response to chemotherapy was found to influence survival. All long-term survivors belonged to the early-stage groups (clinical groups I and II) for which complete surgical excision was possible. In spite of a poor prognosis after relapse, the use of aggressive chemotherapy appeared to prolong life in some patients.

This study was designed to determine if long-term palliation could be obtained in pre-irradiated locoregional recurrent squamous head and neck cancer patients, with the administration of simultaneous chemoradiotherapy. Mandatory eligibility criteria were histologically documented squamous head and neck cancer in previously irradiated territory, surgical or brachytherapy salvage unfeasibility, or patient refusal. The protocol consisted of radiotherapy, at a rate of 5 daily fractions of 2 Gy on alternate weeks, with simultaneous continuous intravenous infusion of 5-fluorouracil (5FU) at 800 mg/m2 and oral hydroxyurea (HU) at 1,000-1,500 mg/day for 5 days. Tolerance was good. Acute toxicity was low with no grade > or = III WHO hematologic toxicity observed. Nine patients had grade III mucositis, one had grade IV, three had grade III skin toxicity, and only four patients required a 20% to 30% 5FU dose reduction because of it. Two patients had hand and foot syndrome, and two had asymptomatic 5FU-related cardiac signs (1 ECG, 1 echographic+ECG). Chronic radiotherapy-related effects consisted of Hermitte's sign observed in two patients. Of 34 registered patients, 33 were evaluable for response. An overall rate of 55% (18 patients) of objective responses [complete response (CR) + partial response (PR)] was obtained, with 12 patients (36%) achieving local control of disease. The median survival was 11 months. These data show that palliation could be obtained for the majority of responding patients, and also suggest an improvement in the immediate prognosis with this type of salvage procedure for a selected group of recurrent squamous head and neck cancer patients.

CPT-11 (I; 7-ethyl-10-[4-(1-piperidino)-1- piperidino]carbonyloxycamptothecin) is a new anticancer agent currently under clinical development. A sensitive high-performance liquid chromatographic assay suitable for the simultaneous determination of I and its active metabolite SN-38 (II) in human plasma, and their preliminary clinical pharmacokinetics, are described. Plasma samples were processed using a solid-phase (C18) extraction step allowing mean recoveries of I, II and the internal standard camptothecin (III) of 84, 99 and 72%, respectively. The extracts were chromatographed on a C18 reversed-phase column with a mobile phase composed of acetonitrile, phosphate buffer and heptanesulphonic acid, with fluorescence detection. The calibration graphs were linear over a wide range of concentrations (1 ng/ml-10 micrograms/ml), and the lower limit of determination was 1 ng/ml for both I and II. The method showed good precision: the within-day relative standard deviation (R.S.D.) (5-1000 ng/ml) was 13.0% (range 4.9-19.4%) for I and 12.8% (6.7-19.1%) for II; the between-day R.S.D. (5-10,000 ng/ml was 7.9% (5.4-17.5%) for I and 9.7% (3.5-15.1%) for II. Using this assay, plasma pharmacokinetics of both I and II were simultaneously determined in three patients receiving 100 mg/m2 I as a 30-min intravenous infusion. The mean peak plasma concentration of I at the end of the intravenous infusion was 2400 +/- 285 ng/ml (mean +/- standard error of the mean). Plasma decay was triphasic with half-lives alpha, beta and gamma of 5.4 +/- 1.8 min, 2.5 +/- 0.5 h and 20.2 +/- 4.6 h, respectively. The volume of distribution at steady state was 105 +/- 15 l/m2, and the total body clearance was 12.5 +/- 1.9 l/h.m2. The maximum concentrations of the active metabolite II reached 36 +/- 11 ng/ml.

Secondary ion mass spectrometry microscopy enables quantitative mapping of chemical elements in tissue sections. It was used for the detection of 127I contained in 4'-iododeoxyrubicin (IDX). Metastatic cutaneous squamous cell carcinoma from 7 patients participating in a phase I study (IDX dose, 80 mg/m2, 10-min i.v. infusion) were biopsied 10 min after drug administration and compared to 3 controls who did not receive any treatment (one squamous cell carcinoma and 2 gastric carcinomas). Biopsy specimens were fixed and embedded in methacrylate resin. Then, serial semithin sections (3 microns) were analyzed simultaneously with ionic and optimal microscopes in order to identify the histological structures given by the 31P distribution in which 127I in IDX was mapped. The iodine signal was undetected in controls and found mainly in the nuclei of tumor cells of the treated patients. Its concentration, measured in at least 30 nuclei of each specimen, was undetectable in 8% of the nuclei and 91% of them were within 1 and 16 ng/mg. The mean concentration of each specimen ranged from 5 to 23 ng/mg. This study demonstrates the capacity of ion microscopy to localize a cytotoxic drug (IDX) in a human biopsy specimen without the need for radioactive labeling and enables the evaluation of drug penetration in cancer cells which is critical for its activity.