Investigation of Photodynamic Therapy Promoted by Cherenkov Light Activated Photosensitizers-New Aspects and Revelations

This work investigates the proposed enhanced efficacy of photodynamic therapy (PDT) by activating photosensitizers (PSs) with Cherenkov light (CL). The approaches of Yoon et al. to test the effect of CL with external radiation were taken up and refined. The results were used to transfer the applied scheme from external radiation therapy to radionuclide therapy in nuclear medicine. Here, the CL for the activation of the PSs (psoralen and trioxsalen) is generated by the ionizing radiation from rhenium-188 (a high-energy beta-emitter, Re-188). In vitro cell survival studies were performed on FaDu, B16 and 4T1 cells. A characterization of the PSs (absorbance measurement and gel electrophoresis) and the CL produced by Re-188 (luminescence measurement) was performed as well as a comparison of clonogenic assays with and without PSs. The methods of Yoon et al. were reproduced with a beam line at our facility to validate their results. In our studies with different concentrations of PS and considering the negative controls without PS, the statements of Yoon et al. regarding the positive effect of CL could not be confirmed. There are slight differences in survival fractions, but they are not significant when considering the differences in the controls. Gel electrophoresis showed a dominance of trioxsalen over psoralen in conclusion of single and double strand breaks in plasmid DNA, suggesting a superiority of trioxsalen as a PS (when irradiated with UVA). In addition, absorption measurements showed that these PSs do not need to be shielded from ambient light during the experiment. An observational test setup for a PDT nuclear medicine approach was found. The CL spectrum of Re-188 was measured. Fluctuating inconclusive results from clonogenic assays were found.

Gamma camera imaging characteristics of 166Ho and 99mTc used in Selective Internal Radiation Therapy

BACKGROUND

The administration of a 166Ho scout dose is available as an alternative to 99mTc particles for pre-treatment imaging in Selective Internal Radiation Therapy (SIRT). It has been reported that the 166Ho scout dose may be more accurate for the prediction of microsphere distribution and the associated therapy planning. The aim of the current study is to compare the scintigraphic imaging characteristics of both isotopes, considering the objectives of the pre-treatment imaging using clinically geared phantoms.

METHODS

Planar and SPECT/CT images were obtained using a NEMA image quality phantom in different phantom setups and another body-shaped phantom with several inserts. The influence of collimator type, count statistics, dead time effects, isotope properties and patient obesity on spatial resolution, contrast recovery and the detectability of small activity accumulations was investigated. Furthermore, the effects of the imaging characteristics on personalized dosimetry are discussed.

RESULTS

The images with 99mTc showed up to 3 mm better spatial resolution, up to two times higher contrast recovery and significantly lower image noise than those with 166Ho. The contrast-to-noise ratio was up to five times higher for 99mTc than for 166Ho. Only when using 99mTc all activity-filled spheres could be distinguished from the activity-filled background. The measurements mimicking an obese patient resulted in a degraded image quality for both isotopes.

CONCLUSIONS

Our measurements demonstrate better scintigraphic imaging properties for 99mTc compared to 166Ho in terms of spatial resolution, contrast recovery, image noise, and lesion detectability. While the 166Ho scout dose promises better prediction of the microsphere distribution, it is important to consider the inferior imaging characteristics of 166Ho, which may affect individualized treatment planning in SIRT.

[Evaluation of risk analysis in treatment with unsealed radioactive substances in nuclear medicine]

Ziel Gemäß den Anforderungen des Strahlenschutzrechts hat vor der erstmaligen Behandlung mit radioaktiven Stoffen eine Risikoanalyse (RA) zu erfolgen. Die Durchführung einer solchen RA im Bereich der universitären Nuklearmedizin wurde 2020 publiziert 1 . Entsprechend den gesetzlichen Bestimmungen hat eine Aktualisierung bei wesentlichen Änderungen von Teilprozessen zu erfolgen. Spätestens nach 3 Jahren wird eine Überprüfung empfohlen. Die Umsetzung und die Ergebnisse der Aktualisierung werden vorgestellt.

Methodik Es erfolgten schrittweise eine Evaluation der im Rahmen der initialen RA abgeleiteten Maßnahmen, eine Analyse eigener meldepflichtiger Vorkommnisse sowie von Vorkommnissen des BfS-geführten Melde- und Informationssystems für bedeutsame Vorkommnisse bei Strahlenanwendungen am Menschen (BeVoMed). Des Weiteren wurde die RA auf neue Therapien ausgeweitet und Teilbewertungen basierend auf aktuellen Erkenntnissen aktualisiert.

Ergebnisse Die im Rahmen der 2019 durchgeführten RA identifizierten Maßnahmen führten für die Radiojodtherapie, die RSO sowie die SIRT zu einer Reduktion der Risikoprioritätszahlen aufgrund einer Erhöhung der Entdeckungswahrscheinlichkeiten. Ein meldepflichtiges Vorkommnis wurde erkannt und analysiert. Die 3-jährige Erfahrung führte zudem bei vielen Prozessen zu einer Reduktion der Auftretenswahrscheinlichkeit.

Schlussfolgerung Die Aktualisierung der RA hat zu einer Reduktion der Risikoprioritätszahl als Maß für die Risikobewertung geführt, was die hohe Sicherheit bei der Durchführung nuklearmedizinischer Therapien unterstreicht. Dieses Resultat spiegelt sich in der geringen Anzahl gemeldeter nuklearmedizinischer Vorkommnisse des zentralen BeVoMed-Systems wider.

Alpha-Emitting Radionuclides: Current Status and Future Perspectives

The use of radionuclides for targeted endoradiotherapy is a rapidly growing field in oncology. In particular, the focus on the biological effects of different radiation qualities is an important factor in understanding and implementing new therapies. Together with the combined approach of imaging and therapy, therapeutic nuclear medicine has recently made great progress. A particular area of research is the use of alpha-emitting radionuclides, which have unique physical properties associated with outstanding advantages, e.g., for single tumor cell targeting. Here, recent results and open questions regarding the production of alpha-emitting isotopes as well as their chemical combination with carrier molecules and clinical experience from compassionate use reports and clinical trials are discussed.

Conformal antireflection coatings for optical dome covers by atomic layer deposition

Complex 3D-shaped optics are difficult to coat with conventional technologies. In this research, large top-open optical glass cubes with a 100 mm side length were functionalized to simulate large dome-shaped optics. Antireflection coatings for the visible range (420-670 nm) and for a single wavelength (550 nm) were applied by atomic layer deposition simultaneously on two and six demonstrators, respectively. Reflectance measurements on both the inner and outer glass surfaces confirm a conformal AR coating with a residual reflectance significantly below 0.3% for visible wavelengths and 0.2% for single wavelengths on nearly the entire surface of the cubes.

Factors influencing the length of hospital stay of patients with anorexia nervosa - results of a prospective multi-center study

BACKGROUND

The length of stay (LOS) strongly influences anorexia nervosa (AN) inpatient weight outcomes. Hence, understanding the predictors of LOS is highly relevant. However, the existing evidence is inconsistent and to draw conclusions, additional evidence is required.

METHODS

We conducted a prospective, multi-center study including adult female inpatients with AN. Using stepwise linear regression, the following demographic and clinical variables were examined as potential predictors for LOS: admission BMI, AN-subtype, age, age of onset, living situation, partnership status, education, previous hospitalization, self-rated depression, anxiety and somatic symptoms (PHQ-9, PHQ-15, GAD-7), self-rated therapy motivation (FEVER) and eating disorder psychopathology (EDI-2 subscale scores).

RESULTS

The average LOS of the sample (n = 176) was 11.8 weeks (SD = 5.2). Longer LOS was associated with lower admission BMI (ß = -1.66; p < .001), purging AN-subtype (ß = 1.91; p = .013) and higher EDI-2 asceticism (ß = 0.12; p = .030). Furthermore, differences between treatment sites were evident.

CONCLUSIONS

BMI at admission and AN-subtype are routinely assessed variables, which are robust and clinically meaningful predictors of LOS. Health care policies might consider these variables. In light of the differences between treatment sites future research on geographical variations in mental health care seems recommended.

Clinical and Functional Outcome of Assertive Outreach for Patients With Schizophrenic Disorder: Results of a Quasi-Experimental Controlled Trial

Background

The majority of studies support modern assertive health service models. However, the evidence is limited for parts of continental Europe, as well as for the pharmacological adherence outcome parameter.

Method

We conducted a quasi-experimental controlled trial including adult patients with a schizophreniform disorder and a maximum of 60 points on the Global Assessment of Functioning Scale (GAF). Interventions (n = 176) and controls (TAU, n = 142) were assessed every six-month within one year in 17 study practices in rural areas. Mental and functional state were rated using the Brief Psychiatric Rating Scale (BPRS) and the GAF. Functional limitations and pharmacological adherence were patient-rated using the WHO-Disability Assessment Schedule II (WHODAS–II) and the Medication Adherence Report Scale (MARS). We computed multilevel mixed models.

Results

The GAF and BPRS of both groups improved significantly, yet the increase in the intervention group was significantly higher. In contrast, patient-rated variables – WHODAS–II and MARS – neither showed a stable temporal improvement nor a difference between groups.

Conclusion

Our findings only partly support the investigated AO intervention, because of conflicting results between clinician- and patient-ratings. Accordingly, the benefits of AO need to be further evaluated.

Developmental patterns of thyroid hormones and testosterone in ferrets

Plasma levels of thyroxine (T4) and triiodothyronine (T3) were measured in male and female ferrets at regular intervals between postnatal day 20 and 150 as well as in adult animals. In addition, testosterone level in male ferrets was measured. All hormones showed characteristic developmental patterns. There is a T4 maximum prior to a T3 maximum in subadult animals which in both cases surpasses adult levels. Testosterone level shows a different developmental pattern. There is an outstanding peak in subadult males around day 60-80, which, however, is surpassed by adult levels during the mating season.

Effects of cyproterone acetate on mating behavior, testicular morphology, testosterone level, and body temperature in male ferrets in comparison with normal and castrated males

Effects of surgical castration of 60-day-old male ferrets are compared with the effects of a chemical castration with cyproterone acetate from postnatal day 60 until 360. Investigations were made on mating behavior, intermale aggression, testicular morphology, plasma testosterone level and body temperature. While controls show seasonal variations in all parameters, according to the annual cycle of sexual activity and inactivity, both, surgically and chemically castrated ferrets show throughout the year constant parameters similar to that of controls during the sexual inactive period. All investigated effects of a long-term treatment with cyproterone acetate are fully reversible within 2 years after termination of drug administration.

[Quantitative changes of rat's alpha 2 macroglobulin concentration by influence of carbon tetrachloride (author's transl)]

We examined the influence of carbon tetrachloride on the rat liver by means of some biological parameters (body mass, GPT-activity, time of hexobarbital narcosis, aminophenazone demethylation) in comparison to the relative concentration of alpha 2 AP under conditions of a long time experiment (8 weeks). The results show, that merely the alpha 2 AP is altered significant in test groups after 1 d of treatment in comparison to the other parameters. Afterwards, under lasting carbon tetrachloride influence the macroglobulin decreases below normal levels. The potential diagnostic value of the alpha 2 AP for toxicological examinations is discussed.

Planning of experiments for the testing of chronic toxicity in rats taking into account biorhythms

During the course of testing chronic toxicity in rats several physiological and biochemical parameters were investigated. Many of the processes studied show a circadian and infradian rhythm, which can clearly be influenced from the second year onwards by age dependent alterations. The daily rhythm of the following processes were investigated: Hexobarbital sleeping time, aminophenazone demethylation, Hb (Hemoglobin), Hc (Hematocrit), GPT (Glutamate-pyruvate-transaminase) and total plasma proteins. The seasonal changes of total plasma proteins, Hexobarbital sleeping time and aniline hydroxylation were also examined. The results obtained indicate, that for comparison and interpretation of data on acute and chronic toxicity the knowledge of daily and seasonal changes is necessary and has to be considered for an exact planning of experiments.