Spectral changes of EEG following a 6-week low-dose oral ketamine treatment in adults with major depressive disorder and chronic suicidality

BACKGROUND

Ketamine has considerable therapeutic potential in alleviating major depressive disorder (MDD) and chronic suicidality. However, the clinical diagnosis of neuropsychiatric disorders requires more robust diagnostic criteria. Electroencephalography (EEG) has shown promise in classifying depressive and suicidal patients from healthy individuals. The present study aimed to identify changes in the spectral properties of EEG in patients with MDD and chronic suicidality after completing the 6-week Oral Ketamine Trial on Suicidality (OKTOS) with follow-up occurring 4 weeks after final ketamine treatment and determine associations between EEG spectral output and clinical symptoms.

METHODS

Participants (N=25) had 4-minutes eyes closed resting state EEG recorded at frontal, temporal, centro-parietal, and occipital regions. Spectral analysis was performed with Welch's power spectrum density method, and the power of four distinct frequency bands was analysed - theta, alpha, low-beta, and high-beta. Correlation analyses between changes in clinical symptoms and spectral power were done using Spearman's ranked correlation.

RESULTS

Between pre- and post-treatment, only centro-parietal alpha power decreased. Between post-treatment and follow-up, centro-parietal alpha increased again in addition to increases in temporal alpha, centro-parietal and temporal theta, occipital low-beta, and decreases in occipital theta and temporal low-beta. Additionally, the decrease of occipital theta positively correlated with clinical subscales for depression and stress.

CONCLUSIONS

EEG spectral analysis revealed significant changes in theta, alpha, and low-beta frequency bands. Alpha band showed initial changes after treatment; however, this trended back towards baseline levels after the treatment cessation. In contrast, theta and low-beta showed significant power changes only after the treatment had ended.

MIR-NATs repress MAPT translation and aid proteostasis in neurodegeneration

The human genome expresses thousands of natural antisense transcripts (NAT) that can regulate epigenetic state, transcription, RNA stability or translation of their overlapping genes1,2. Here we describe MAPT-AS1, a brain-enriched NAT that is conserved in primates and contains an embedded mammalian-wide interspersed repeat (MIR), which represses tau translation by competing for ribosomal RNA pairing with the MAPT mRNA internal ribosome entry site3. MAPT encodes tau, a neuronal intrinsically disordered protein (IDP) that stabilizes axonal microtubules. Hyperphosphorylated, aggregation-prone tau forms the hallmark inclusions of tauopathies4. Mutations in MAPT cause familial frontotemporal dementia, and common variations forming the MAPT H1 haplotype are a significant risk factor in many tauopathies5 and Parkinson's disease. Notably, expression of MAPT-AS1 or minimal essential sequences from MAPT-AS1 (including MIR) reduces-whereas silencing MAPT-AS1 expression increases-neuronal tau levels, and correlate with tau pathology in human brain. Moreover, we identified many additional NATs with embedded MIRs (MIR-NATs), which are overrepresented at coding genes linked to neurodegeneration and/or encoding IDPs, and confirmed MIR-NAT-mediated translational control of one such gene, PLCG1. These results demonstrate a key role for MAPT-AS1 in tauopathies and reveal a potentially broad contribution of MIR-NATs to the tightly controlled translation of IDPs6, with particular relevance for proteostasis in neurodegeneration.

Distinct responses of neurons and astrocytes to TDP-43 proteinopathy in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal and incurable neurodegenerative disease caused by motor neuron loss, resulting in muscle wasting, paralysis and eventual death. A key pathological feature of ALS is cytoplasmically mislocalized and aggregated TDP-43 protein in >95% of cases, which is considered to have prion-like properties. Historical studies have predominantly focused on genetic forms of ALS, which represent ∼10% of cases, leaving the remaining 90% of sporadic ALS relatively understudied. Additionally, the role of astrocytes in ALS and their relationship with TDP-43 pathology is also not currently well understood. We have therefore used highly enriched human induced pluripotent stem cell (iPSC)-derived motor neurons and astrocytes to model early cell type-specific features of sporadic ALS. We first demonstrate seeded aggregation of TDP-43 by exposing human iPSC-derived motor neurons to serially passaged sporadic ALS post-mortem tissue (spALS) extracts. Next, we show that human iPSC-derived motor neurons are more vulnerable to TDP-43 aggregation and toxicity compared with their astrocyte counterparts. We demonstrate that these TDP-43 aggregates can more readily propagate from motor neurons into astrocytes in co-culture paradigms. We next found that astrocytes are neuroprotective to seeded aggregation within motor neurons by reducing (mislocalized) cytoplasmic TDP-43, TDP-43 aggregation and cell toxicity. Furthermore, we detected TDP-43 oligomers in these spALS spinal cord extracts, and as such demonstrated that highly purified recombinant TDP-43 oligomers can reproduce this observed cell-type specific toxicity, providing further support to a protein oligomer-mediated toxicity hypothesis in ALS. In summary, we have developed a human, clinically relevant, and cell-type specific modelling platform that recapitulates key aspects of sporadic ALS and uncovers both an initial neuroprotective role for astrocytes and the cell type-specific toxic effect of TDP-43 oligomers.

Three-Dimensional Human iPSC-Derived Artificial Skeletal Muscles Model Muscular Dystrophies and Enable Multilineage Tissue Engineering

Generating human skeletal muscle models is instrumental for investigating muscle pathology and therapy. Here, we report the generation of three-dimensional (3D) artificial skeletal muscle tissue from human pluripotent stem cells, including induced pluripotent stem cells (iPSCs) from patients with Duchenne, limb-girdle, and congenital muscular dystrophies. 3D skeletal myogenic differentiation of pluripotent cells was induced within hydrogels under tension to provide myofiber alignment. Artificial muscles recapitulated characteristics of human skeletal muscle tissue and could be implanted into immunodeficient mice. Pathological cellular hallmarks of incurable forms of severe muscular dystrophy could be modeled with high fidelity using this 3D platform. Finally, we show generation of fully human iPSC-derived, complex, multilineage muscle models containing key isogenic cellular constituents of skeletal muscle, including vascular endothelial cells, pericytes, and motor neurons. These results lay the foundation for a human skeletal muscle organoid-like platform for disease modeling, regenerative medicine, and therapy development.

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Human iPSC-derived 3D artificial muscles show features of normal skeletal muscle

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Multiple muscular dystrophy iPSC lines can be differentiated in 3D artificial muscles

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Artificial muscle constructs model severe, incurable forms of muscular dystrophy

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Isogenic vascular-like networks and motor neurons develop within artificial muscles

Widespread FUS mislocalization is a molecular hallmark of amyotrophic lateral sclerosis

Mutations causing amyotrophic lateral sclerosis (ALS) clearly implicate ubiquitously expressed and predominantly nuclear RNA binding proteins, which form pathological cytoplasmic inclusions in this context. However, the possibility that wild-type RNA binding proteins mislocalize without necessarily becoming constituents of cytoplasmic inclusions themselves remains relatively unexplored. We hypothesized that nuclear-to-cytoplasmic mislocalization of the RNA binding protein fused in sarcoma (FUS), in an unaggregated state, may occur more widely in ALS than previously recognized. To address this hypothesis, we analysed motor neurons from a human ALS induced-pluripotent stem cell model caused by the VCP mutation. Additionally, we examined mouse transgenic models and post-mortem tissue from human sporadic ALS cases. We report nuclear-to-cytoplasmic mislocalization of FUS in both VCP-mutation related ALS and, crucially, in sporadic ALS spinal cord tissue from multiple cases. Furthermore, we provide evidence that FUS protein binds to an aberrantly retained intron within the SFPQ transcript, which is exported from the nucleus into the cytoplasm. Collectively, these data support a model for ALS pathogenesis whereby aberrant intron retention in SFPQ transcripts contributes to FUS mislocalization through their direct interaction and nuclear export. In summary, we report widespread mislocalization of the FUS protein in ALS and propose a putative underlying mechanism for this process.

G-quadruplex-binding small molecules ameliorate C9orf72 FTD/ALS pathology in vitro and in vivo

Intronic GGGGCC repeat expansions in C9orf72 are the most common known cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), which are characterised by degeneration of cortical and motor neurons, respectively. Repeat expansions have been proposed to cause disease by both the repeat RNA forming foci that sequester RNA‐binding proteins and through toxic dipeptide repeat proteins generated by repeat‐associated non‐ATG translation. GGGGCC repeat RNA folds into a G‐quadruplex secondary structure, and we investigated whether targeting this structure is a potential therapeutic strategy. We performed a screen that identified three structurally related small molecules that specifically stabilise GGGGCC repeat G‐quadruplex RNA. We investigated their effect in C9orf72 patient iPSC‐derived motor and cortical neurons and show that they significantly reduce RNA foci burden and the levels of dipeptide repeat proteins. Furthermore, they also reduce dipeptide repeat proteins and improve survival in vivo, in GGGGCC repeat‐expressing Drosophila. Therefore, small molecules that target GGGGCC repeat G‐quadruplexes can ameliorate the two key pathologies associated with C9orf72 FTD/ALS. These data provide proof of principle that targeting GGGGCC repeat G‐quadruplexes has therapeutic potential.

Intron retention and nuclear loss of SFPQ are molecular hallmarks of ALS

Mutations causing amyotrophic lateral sclerosis (ALS) strongly implicate ubiquitously expressed regulators of RNA processing. To understand the molecular impact of ALS-causing mutations on neuronal development and disease, we analysed transcriptomes during in vitro differentiation of motor neurons (MNs) from human control and patient-specific VCP mutant induced-pluripotent stem cells (iPSCs). We identify increased intron retention (IR) as a dominant feature of the splicing programme during early neural differentiation. Importantly, IR occurs prematurely in VCP mutant cultures compared with control counterparts. These aberrant IR events are also seen in independent RNAseq data sets from SOD1- and FUS-mutant MNs. The most significant IR is seen in the SFPQ transcript. The SFPQ protein binds extensively to its retained intron, exhibits lower nuclear abundance in VCP mutant cultures and is lost from nuclei of MNs in mouse models and human sporadic ALS. Collectively, we demonstrate SFPQ IR and nuclear loss as molecular hallmarks of familial and sporadic ALS.

Sense and antisense RNA are not toxic in Drosophila models of C9orf72-associated ALS/FTD

A GGGGCC hexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Neurodegeneration may occur via transcription of the repeats into inherently toxic repetitive sense and antisense RNA species, or via repeat-associated non-ATG initiated translation (RANT) of sense and antisense RNA into toxic dipeptide repeat proteins. We have previously demonstrated that regular interspersion of repeat RNA with stop codons prevents RANT (RNA-only models), allowing us to study the role of repeat RNA in isolation. Here we have created novel RNA-only Drosophila models, including the first models of antisense repeat toxicity, and flies expressing extremely large repeats, within the range observed in patients. We generated flies expressing ~ 100 repeat sense or antisense RNA either as part of a processed polyadenylated transcript or intronic sequence. We additionally created Drosophila expressing > 1000 RNA-only repeats in the sense direction. When expressed in adult Drosophila neurons polyadenylated repeat RNA is largely cytoplasmic in localisation, whilst intronic repeat RNA forms intranuclear RNA foci, as does > 1000 repeat RNA, thus allowing us to investigate both nuclear and cytoplasmic RNA toxicity. We confirmed that these RNA foci are capable of sequestering endogenous Drosophila RNA-binding proteins, and that the production of dipeptide proteins (poly-glycine–proline, and poly-glycine–arginine) is suppressed in our models. We find that neither cytoplasmic nor nuclear sense or antisense RNA are toxic when expressed in adult Drosophila neurons, suggesting they have a limited role in disease pathogenesis.

Genome-wide association study of immunoglobulin light chain amyloidosis in three patient cohorts: comparison with myeloma

Immunoglobulin light chain (AL) amyloidosis is characterized by tissue deposition of amyloid fibers derived from immunoglobulin light chain. AL amyloidosis and multiple myeloma (MM) originate from monoclonal gammopathy of undetermined significance. We wanted to characterize germline susceptibility to AL amyloidosis using a genome-wide association study (GWAS) on 1229 AL amyloidosis patients from Germany, UK and Italy, and 7526 healthy local controls. For comparison with MM, recent GWAS data on 3790 cases were used. For AL amyloidosis, single nucleotide polymorphisms (SNPs) at 10 loci showed evidence of an association at P<10^-5 with homogeneity of results from the 3 sample sets; some of these were previously documented to influence MM risk, including the SNP at the IRF4 binding site. In AL amyloidosis, rs9344 at the splice site of cyclin D1, promoting translocation (11;14), reached the highest significance, P=7.80 × 10^-11; the SNP was only marginally significant in MM. SNP rs79419269 close to gene SMARCD3 involved in chromatin remodeling was also significant (P=5.2 × 10^-8). These data provide evidence for common genetic susceptibility to AL amyloidosis and MM. Cyclin D1 is a more prominent driver in AL amyloidosis than in MM, but the links to aggregation of light chains need to be demonstrated.

Atomistic simulations reveal bubbles, kinks and wrinkles in supercoiled DNA

Although DNA is frequently bent and supercoiled in the cell, much of the available information on DNA structure at the atomistic level is restricted to short linear sequences. We report atomistic molecular dynamics (MD) simulations of a series of DNA minicircles containing between 65 and 110 bp which we compare with a recent biochemical study of structural distortions in these tight DNA loops. We have observed a wealth of non-canonical DNA structures such as kinks, denaturation bubbles and wrinkled conformations that form in response to bending and torsional stress. The simulations show that bending alone is sufficient to induce the formation of kinks in circles containing only 65 bp, but we did not observe any defects in simulations of larger torsionally relaxed circles containing 110 bp over the same MD timescales. We also observed that under-winding in minicircles ranging in size from 65 to 110 bp leads to the formation of single stranded bubbles and wrinkles. These calculations are used to assess the ability of atomistic MD simulations to determine the structure of bent and supercoiled DNA.

Advances in equine practice management

As equine practices move forward in the 21st century, we feel increasing pressure to manage our businesses like business people. This requires outside expertise, in-house business-trained managers, and continuing education on various aspects of practice life. Aside from the AAEP, several other organizations are providing continuing education in management, including the Association of Veterinary Practice Managers, the Veterinary Management Institute offered at Purdue University Krannert Graduate School of Management, the American Animal Hospital Association through (The Virginia-Maryland Regional College of Veterinary Medicine's) on-line practice management course, and the University of Illinois Equine Practice Management modules.

Technical Note: Protein Conjugate-Based Immunoassay of Whole Milk Progesterone

The objectives were to develop a novel protein conjugate-based ELISA test for whole milk progesterone with a dynamic range capable of fully profiling estrous cycles in the dairy cow and to study effects of whole milk medium on antibody binding to progesterone-protein conjugates. A series of progesterone-4-ovalbumin conjugates with different length intermediate linkers were applied as coating antigens in an ELISA format to determine antibody-binding performance in whole milk. Use of an 18-atom linker gave higher binding than use of a 4- or 11-atom linker at certain conjugate concentrations, but no further increase was observed with increasing linker length. An ELISA constructed with the 18-atom linker conjugate gave a detection limit of 0.089 ng/mL progesterone and correlated well to an established radioimmunoassay procedure (r = 0.94). The assay has the distinct advantages of a wide linear range (0.1 to 100 ng/mL), allowing full profiling of bovine estrous cycles, use of whole milk directly without extraction or prior dilution, and employing more easily purified protein conjugates as coating antigens compared with commercial progesterone-enzyme conjugate for milk ELISA assays.

Effect of pravastatin on cardiovascular events in women after myocardial infarction: the cholesterol and recurrent events (CARE) trial

OBJECTIVES

We sought to determine the effect of pravastatin on recurrent cardiovascular events in women with average cholesterol levels after myocardial infarction (MI).

BACKGROUND

Little information is available on the effectiveness of lipid lowering in secondary prevention of coronary heart disease (CHD) in women; in particular, those with CHD and average cholesterol levels.

METHODS

In the Cholesterol and Recurrent Events (CARE) trial, 576 postmenopausal women, between 3 and 20 months after MI, with a total cholesterol level <240 mg/dl and a low density lipoprotein cholesterol level 115 to 174 mg/dl, were randomized to receive pravastatin 40 mg/day or matching placebo for a median follow-up period of 5 years. The main outcome measures were combined coronary events (coronary death, nonfatal MI, percutaneous transluminal coronary angioplasty [PTCA] or coronary artery bypass graft surgery [CABG]), the primary trial end point (coronary death or nonfatal MI) and stroke.

RESULTS

Women treated with pravastatin had a risk reduction of 43% for the primary end point (p = 0.035), 46% for combined coronary events (p = 0.001), 48% for PTCA (p = 0.025), 40% for CABG (p = 0.14) and 56% for stroke (p = 0.07). The 3,583 men in the CARE trial also showed a reduction in risk, but the magnitude tended to be less. Pravastatin improved plasma lipids similarly in men and women. There were no differences in risk of coronary events in the placebo group between men and women. Minor differences between men and women were present in baseline characteristics and treatment for MI, in general, conferring a higher risk status and a lower incidence of CABG in the women.

CONCLUSIONS

Pravastatin led to significant early reduction of a wide range of cardiovascular events in post-MI women with average cholesterol levels.

The development of a [211AT]-astatinated endoradiotherapeutic drug: part IV--late radiation effects

PURPOSE

6-[211At]-astato-MNDP is a high-LET endoradiotherapeutic drug that selectively targets to an oncogenically associated alkaline phosphatase isoenzyme expressed by certain tumors. A detailed histopathological study of the late tissue effects of its endogenous alpha-particle emissions has been carried out in a murine tumor model.

MATERIALS AND METHODS

Thyroid-blocked male C57BI/10 mice bearing a s.c. transplanted rectal adenocarcinoma were treated with a single i.p. injection of 10-750 kBq 6-[211At]-astato-MNDP. Cured mice (131) were studied. Detailed autopsies and histological examinations were performed on all mice. The study was concluded after 756 days.

RESULTS

Lymphoma, plasmacytoma, and intercurrent infections secondary to chronic pulmonary fibrosis were the most commonly found late manifestations of alpha-radiation exposure. Low grade B-cell non-Hodgkin's lymphoma occurred in 19 (24.7%) of 77 mice, 13-17 months after receiving 3.5-185 kBq 6-[211At]-astato-MNDP. The incidence of lymphoma alone and its latency was similar to that of the control population (23.3%). Treatment doses exceeding 200 kBq 6-[211At]-astato-MNDP, were associated with the development of soft tissue plasmacytoma in 7 (13%) of 54 mice, after 17-22 months. Generalized debilitation and nonspecific infections supervening pulmonary fibrosis significantly contributed to the late morbidity and mortality observed in mice treated with 300-750 kBq 6-[211At]-astato-MNDP. Dosimetry has afforded LD50/360 and LD50/420 estimates of 12-14 and 10-12 Cobalt-Gray equivalent (CGyE), respectively, for chronic lung damage. There was no histological evidence of chronic radiation damage to other critical healthy tissues. Normal thyroid morphology was preserved.

CONCLUSIONS

Dose activities of 6-[211At]-astato-MNDP exceeding 300 kBq, were associated an increased risk of tumor induction and development of varying degrees of chronic pulmonary fibrosis implicated in the onset of terminal intercurrent infections. Within the therapeutic dose range 55-300 kBq 6-[211At]-astato-MNDP, mortality associated with the incidence of significant late radiation damage in critical normal tissues and latent carcinogenesis was less than 15%. Data from this murine model suggest that clinically relevant activities of 6-[211At]-astato-MNDP may be given without unacceptable toxicity.

The development of a [211At]-astatinated endoradiotherapeutic drug: Part II. Therapeutic results for transplanted adenocarcinoma of the rectum in mice and associated studies

PURPOSE

6-[211At]-astato-MNDP is of a class of a high linear energy transfer endoradiotherapeutic drug, which selectively targets to an onco-APase isoenzyme expressed by certain epithelial and germ cell tumors. The therapeutic efficacy and acute toxicity of its endogenous alpha-particle emissions have been studied in a murine tumor model.

METHODS AND MATERIALS

211At was produced by the 207Bi(alpha,2n)211 At cyclotron-based nuclear reaction. High specific activity 6-[211At]-astato-MNDP was rapidly synthesized by in vacuo thermal heterogeneous isotopic exchange. The therapeutic potential of 6-[211At]-astato-MNDP and 211At- was determined in mice bearing a transplanted CMT-93 rectal carcinoma which exhibited onco-APase activity.

RESULTS

Significant therapeutic effects due to targeted alpha-particle emissions have been confirmed for the activity dose range, 10-750 kBq 6-[211At]-astato-MNDP. A therapeutic window has been identified, whereby cure rates of approximately 45-65% were achieved following administration of 55-300 kBq 6-[211At]-astato-MNDP. Estimated tumor absorbed radiation doses were not inconsistent with clinical response. Irreversible hematoxicity or stigmata of acute radiation damage in other critical normal tissues were not encountered. Nonspecifically internalized 211At- exerted no therapeutic effect.

CONCLUSION

Therapeutic results for 6-[211At]-astato-MNDP have confirmed the profound in vivo cytotoxicity of its targeted alpha-radiations in the CMT-93 tumor. Acute normal tissue toxicity was acceptable. A rationale for optimal fractionation of targeted 6-[211At]-astato-MNDP endoradiotherapy is discussed, and its putative role in the possible individualized management of certain human tumors has been proposed.

Malonyl coenzyme A decarboxylase deficiency

Two new cases of malonyl coenzyme A (CoA) decarboxylase deficiency are described. Hitherto, the worldwide experience of the disorder has been confined to reports on two affected Australian children. The new cases are Scots born and are the offspring of consanguinous parents of Scots/Irish origin. They were investigated during episodes of vomiting and febrile convulsions associated with concomitant developmental delay. Malonic aciduria and grossly reduced malonyl CoA decarboxylase activity were demonstrated and the total ion current chromatograms of urinary organic acid profiles obtained by gas chromatography-mass spectrometry are presented. The clinical and biochemical features of the Scots and Australian patients are compared.

The development of A [211At]-astatinated endoradiotherapeutic drug: Part I. Localization by alpha-particle autoradiography in a murine tumor model

Alpha-particle track autoradiography has been used to define the in vivo cellular and intracellular distribution of radioactivity from the potential high linear energy transfer endoradiotherapeutic drug, 6-[211At]-astato-2-methyl-1,4-naphthoquinol bis(diphosphate) in tumor and relevant critical normal tissues of mice bearing a transplanted murine rectal carcinoma. A strikingly selective uptake of this compound into tumor cells, particularly into specific tumor cell nuclei, has been demonstrated. Its localization in certain tumor cells appears to depend on the presence of an onco-product, in this case an alkaline phosphatase isoenzyme, which is synthesized in some tumor cells and to which the compound targets. In curable tumors, it selectively concentrates in cells which may be regarded as tumor stem cells. There is low uptake into normal cells, particularly those in bone marrow, colon, and lung, where its sequestration is mainly extranuclear.

Uptake and therapeutic effectiveness of 125I- and 211At-methylene blue for pigmented melanoma in an animal model system

The investigations concerning a targeted radiotherapy for pigmented melanoma with a radiolabeled phenothiazine derivative, 3,7-(dimethylamino)phenazathionium chloride [methylene blue (MTB)], were continued using melanotic and amelanotic sublines of B16 melanoma. Two radionuclides, 125I and 211At, emitting Auger electrons and alpha particles, respectively, replaced 35S previously studied since their biological effectiveness is significantly higher. In vitro autoradiography revealed a selective accumulation of methylene blue labeled with either of the radioisotopes in pigmented melanoma cells but its absence in nonpigmented cells. Treatments with [125I]MTB and [211At]MTB were performed both in vitro and in vivo, with their effectiveness determined by lung clonogenic assay. [125I]MTB proved to be relatively ineffective when incorporated into melanosomes distributed in the cytoplasm, i.e., too far away from the genome. Conspicuous therapeutic effects were achieved with [211At]MTB for pigmented melanoma only. 211At itself did not affect either of the investigated sublines of B16 melanoma confirming once again the high affinity of methylene blue to melanin. Calculations of cumulative radiation doses from [211At]MTB deposited in melanotic melanoma tumors and pigmented normal organs which would be at a particular risk led to the conclusion that [211At]MTB could be used for a highly selective and very efficient targeted radiotherapy of pigmented melanomas without damaging normal tissues.

Alpha-particle track autoradiographic study of the distribution of a [211At]-astatinated drug in normal tissues of the mouse

The microscopic distribution of the potential endoradiotherapeutic drug, 6-[211At]-astato-2-methyl-1,4- naphthoquinol bis (diphosphate salt) in normal tissues of the mouse has been studied by alpha-particle track autoradiography. The uptake into critical radiosensitive tissues, especially bone marrow, colon and lung, was low.

Biodistribution of 6-[211At]astato-2-methyl-1,4-naphthoquinol bis(diphosphate salt) and 211At- in mice with a transplanted rectal adenocarcinoma

6-[211At]astato-MNDP is currently being investigated as a potential high LET endoradiotherapeutic drug. Biodistribution and whole-body radiation retention studies have been carried out with 6-[211At]astato-MNDP and 211At- in a murine rectal tumour model; results indicate that the 211At-C bond in the compound is metabolically stable for at least 6 h. The Mean Biological Concentration of 6-[211At]astato-MNDP in tumour tissue ranged from 170-253% over an initial 12 h period; this was higher than that observed for the [211At]astatide anion. Conversely, the uptake of compound into radiobiologically critical organs was significantly lower.

alpha-Particle track autoradiography for localization of a 211At-astatinated drug

A potential endoradiotherapeutic drug, 6-211At-astato-2-methyl-1,4-naphthoquinol bis (diphosphate salt), incorporating the alpha-emitting radio-halogen astatine-211 of half-life 7.2 h, is shown to be valuable for localization studies by means of alpha-particle track autoradiography in malignant and normal cells and tissues in the mouse with transplanted adenocarcinoma of the rectum.

The in vitro selective concentration of an 125I-iodinated compound in human tumor cells

Uptake studies of the potential endoradiotherapeutic agent, 6-125I-iodo-2-methyl-1,4-naphthoquinol bis(diammonium phosphate) have been carried out in vitro on a wide range of normal and malignant human cells. In general, for a standardized dose of 0.1 microCi/ml, the uptake of the compound into normal cells was 0.0015-0.135 pCi/cell. Uptake into malignant cells was significantly higher than normal cells; uptakes of 0.89-11.3 pCi/cell were noted for melanoma, teratoma of testis, osteosarcoma and adenocarcinoma of colon and pancreas. Comparative uptake ratios for melanoma: Chang liver cells and testicular teratoma:normal testis were 29 23, respectively. Larger uptake ratios are usually observed with higher doses.

6-125I-iodo-2-methyl-1,4-naphthoquinol bis (diammonium phosphate) as a potential radio-halogenated anti-cancer agent: in vitro investigations and possible clinical implications

6-125-I-iodo-2-methyl-1,4-naphthoquinol bis (diammonium phosphate) (6-125I-iodo-MNDP) has been synthesised and studied as the prototype of a class of potential radio-halogenated anti-cancer agents. The incorporated 125I provides Auger electron radiations which behave like high LET radiations in the treatment of tumours, though the accompanying X- and gamma-radiations make an undesirable contribution to the total body dose. The in vitro experiments reported show that 6-125I-iodo-MNDP is selectively concentrated in the cells of some human malignant tumours by factor of about 15 to 20 or more in relation to the cells of normal origin studied. On the basis of dosimetric considerations and comparison with clinical treatment with tritiated methylnaphthoquinol diphosphate, practical dosage of 6-125I-iodo-MNDP is suggested and clinical indications and safety of use are discussed. The types of tumour of particular interest are inoperable cases of carcinoma of the colon, carcinoma of the pancreas, malignant melanoma and osteosarcoma. Further investigations are in progress.

[Influence of vitamins of the B-group upon cancer patients treated by irradiation: I. Vitamin B6 in local irradiation of tumour rats (author's transl)]

Eleven hundred rats with tumours were administered vitamin B6 (pyridoxine or pyridoxal-5-phosphate) before a single local irradiation of 10 Gy. No difference in the survival rate was found in comparison with control animals. Thus vitamin B6 in the dose used afforded no significant protection against local radiation in rats. The 24-hour-xanthurenic acid excretion in urine increased with growth of the tumor and was further elevated by local radiation (10 Gy). Radiation as well as the tumour itself induce in the rat metabolic changes typical of vitamin B6 deficiency.

Effects of norlaudanosolinecarboxylic acids on enzymes of catecholamine metabolism

Enzymes involved in catecholamine metabolism were assayed in the presence of a new class of naturally occurring tetrahydroisoquinoline alkaloids, the norlaudanosolinecarboxylic acids (NLCAs). NLCAs inhibited tyrosine hydroxylase noncompetitively with respect to its substrate, tyrosine and the cofactor, 6-methyltetrahydropterin (NLCA Kj = 4 x 10(-4) M; 3',4'-deoxynorlaudanosolinecarboxylic acid (DNLCA) Kj = 1.5 x 10(-4) M). Adrenal dopamine-beta-hydroxylase was also inhibited by NLCAs [3'O-methylnorlaudanosolinecarboxylic acid (MNLCA) Kj = 1.2 x 10(-4) M] and NLCA is a competitive inhibitor of norepinephrine methylation by hepatic catechol-O-methyltransferase (NLCA Kj = 5.6 x 10(-5) M). While a slight reduction of rat adrenal monoamine oxidase by MNLCA was also observed, NLCA did not affect the oxidation of tyrosine by D-amino acid oxidase. Kinetic patterns of tyrosine aminotransferase and aromatic amono acid decarboxylase from rat liver were not altered by addition of 1 to 10 x 10(-5) M NLCA or its 3'-O-methyl ether (MNLCA). In vivo studies of brain tyrosine metabolism in mouse neonates corroborated results on the in vitro effect of DNLCA on tyrosine hydroxylase. The potential of high-pressure liquid chromatography was demonstrated in both enzyme assays and radiometric studies of in vivo metabolism.

A simple after-loading technique for the treatment of cancer of the cervix

A simple manual after-loading system for the treatment of carcinoma of the cervix has been developed. Radiochemical Centre J-type caesium sources are used made up in PVC tubes which can be inserted into PVC uterine tubes or rubber ovoids after these have been packed in position in the patient. Radiation exposure to theatre staff has been reduced by a factor of about four.

Investigations of tritiated menadiol sodium diphosphate (T-MNDP) as a radioactive drug

An attempt has been made to develop tritiated derivatives of Synkavit (menadiol sodium diphosphate, MNDP) of high specific activity as a radioactive drug.This paper summarizes the preliminary biological and physical studies, with emphasis on approximate radiation dosimetry and the necessary preliminary testing, and then gives an account of the clinical investigations and the trials carried out so far, which correspond essentially to Phases I and II trials for a chemotherapeutic agent.In all, 214 patients with different sites and types of advanced and recurrent, inoperable, histologically verified malignant tumours including reticuloses have been treated with doses of at least 1 Ci of the various preparations. Among the 203 evaluable treated cases, some form of response was observed in 23 out of 151 (15·2%) receiving the drug by intravenous injections and 13 out of 52 (25%) after intra-arterial injections. For the sites and types of malignant diseases which showed responses after either intravenous or intra-arterial administration among the 55 patients surviving at least 3 months after the first injection, some form of response was observed in 32 but only 5 of these showed either a "complete" or a "partial" response.It is concluded that further investigation is desirable. It is suggested that clinical trials with randomization should be carried out for inoperable cases of carcinoma of the colon and of the pancreas.