Targeting PHGDH reverses the immunosuppressive phenotype of tumor-associated macrophages through α-ketoglutarate and mTORC1 signaling

Phosphoglycerate dehydrogenase (PHGDH) has emerged as a crucial factor in macromolecule synthesis, neutralizing oxidative stress, and regulating methylation reactions in cancer cells, lymphocytes, and endothelial cells. However, the role of PHGDH in tumor-associated macrophages (TAMs) is poorly understood. Here, we found that the T helper 2 (Th2) cytokine interleukin-4 and tumor-conditioned media upregulate the expression of PHGDH in macrophages and promote immunosuppressive M2 macrophage activation and proliferation. Loss of PHGDH disrupts cellular metabolism and mitochondrial respiration, which are essential for immunosuppressive macrophages. Mechanistically, PHGDH-mediated serine biosynthesis promotes α-ketoglutarate production, which activates mTORC1 signaling and contributes to the maintenance of an M2-like macrophage phenotype in the tumor microenvironment. Genetic ablation of PHGDH in macrophages from tumor-bearing mice results in attenuated tumor growth, reduced TAM infiltration, a phenotypic shift of M2-like TAMs toward an M1-like phenotype, downregulated PD-L1 expression and enhanced antitumor T-cell immunity. Our study provides a strong basis for further exploration of PHGDH as a potential target to counteract TAM-mediated immunosuppression and hinder tumor progression.

Hazard characterization of Alternaria toxins to identify data gaps and improve risk assessment for human health

Fungi of the genus Alternaria are ubiquitous plant pathogens and saprophytes which are able to grow under varying temperature and moisture conditions as well as on a large range of substrates. A spectrum of structurally diverse secondary metabolites with toxic potential has been identified, but occurrence and relative proportion of the different metabolites in complex mixtures depend on strain, substrate, and growth conditions. This review compiles the available knowledge on hazard identification and characterization of Alternaria toxins. Alternariol (AOH), its monomethylether AME and the perylene quinones altertoxin I (ATX-I), ATX-II, ATX-III, alterperylenol (ALP), and stemphyltoxin III (STTX-III) showed in vitro genotoxic and mutagenic properties. Of all identified Alternaria toxins, the epoxide-bearing analogs ATX-II, ATX-III, and STTX-III show the highest cytotoxic, genotoxic, and mutagenic potential in vitro. Under hormone-sensitive conditions, AOH and AME act as moderate xenoestrogens, but in silico modeling predicts further Alternaria toxins as potential estrogenic factors. Recent studies indicate also an immunosuppressive role of AOH and ATX-II; however, no data are available for the majority of Alternaria toxins. Overall, hazard characterization of Alternaria toxins focused, so far, primarily on the commercially available dibenzo-α-pyrones AOH and AME and tenuazonic acid (TeA). Limited data sets are available for altersetin (ALS), altenuene (ALT), and tentoxin (TEN). The occurrence and toxicological relevance of perylene quinone-based Alternaria toxins still remain to be fully elucidated. We identified data gaps on hazard identification and characterization crucial to improve risk assessment of Alternaria mycotoxins for consumers and occupationally exposed workers.

Human serum albumin as a copper source for anticancer thiosemicarbazones

Thiosemicarbazones (TSCs) are a class of biologically active compounds with promising anticancer activity. Their typical mechanism, especially of the clinically far developed representative Triapine, is chelation of iron (Fe), with the Fe-containing enzyme ribonucleotide reductase as primary intracellular target. However, for the subclass of terminally disubstituted, nanomolar-active derivatives like Dp44mT and Me2NNMe2, recent findings suggest that the chelation, stability, and reduction properties of the copper(II) (Cu) complexes are essential for their modes of action. Consequently, it is important to elucidate whether blood serum Cu(II) is a potential metal source for these TSCs. To gain more insights, the interaction of Triapine, Dp44mT or Me2NNMe2 with purified human serum albumin (HSA) as the main pool of labile Cu(II) was investigated by UV-vis and electron paramagnetic resonance measurements. Subsequently, a size-exclusion chromatography inductively coupled plasma mass spectrometry method for the differentiation of Cu species in serum was developed, especially separating the non-labile Cu enzyme ceruloplasmin from HSA. The results indicate that the TSCs specifically chelate copper from the N-terminal Cu-binding site of HSA. Furthermore, the Cu(II)-TSC complexes were shown to form ternary HSA conjugates, most likely via histidine. Noteworthy, Fe-chelation from transferrin was not overserved, even not for Triapine. In summary, the labile Cu pool of HSA is a potential source for Cu-TSC complex formation and, consequently, distinctly influences the anticancer activity and pharmacological behavior of TSCs.

Degradable Bottlebrush Polypeptides and the Impact of their Architecture on Cell Uptake, Pharmacokinetics, and Biodistribution In Vivo

Bottlebrush polymers are highly promising as unimolecular nanomedicines due to their unique control over the critical parameters of size, shape and chemical function. However, since they are prepared from biopersistent carbon backbones, most known bottlebrush polymers are non-degradable and thus unsuitable for systemic therapeutic administration. Herein, we report the design and synthesis of novel poly(organo)phosphazene-g-poly(α-glutamate) (PPz-g-PGA) bottlebrush polymers with exceptional control over their structure and molecular dimensions (Dh ≈ 15-50 nm). These single macromolecules show outstanding aqueous solubility, ultra-high multivalency and biodegradability, making them ideal as nanomedicines. While well-established in polymer therapeutics, it has hitherto not been possible to prepare defined single macromolecules of PGA in these nanosized dimensions. A direct correlation was observed between the macromolecular dimensions of the bottlebrush polymers and their intracellular uptake in CT26 colon cancer cells. Furthermore, the bottlebrush macromolecular structure visibly enhanced the pharmacokinetics by reducing renal clearance and extending plasma half-lives. Real-time analysis of the biodistribution dynamics showed architecture-driven organ distribution and enhanced tumor accumulation. This work, therefore, introduces a robust, controlled synthesis route to bottlebrush polypeptides, overcoming limitations of current polymer-based nanomedicines and, in doing so, offers valuable insights into the influence of architecture on the in vivo performance of nanomedicines.

Abstract 4901: The role of protein disulfide isomerase and copper in the paraptotic cell death of clinically investigated anticancer thiosemicarbazones

α-N-Heterocyclic thiosemicarbazones (TSCs) have long been investigated as anticancer compounds. Triapine is one of the best-known TSCs for anticancer therapy and is currently tested in a clinical phase III trial. To further improve the anticancer activity of TSCs, novel derivatives (such as DpC and COTI-2) have been developed and clinically investigated for their activity against solid tumors. These novel TSCs belong to a subclass (incl. the tetra-methylated Triapine derivative, Me2NNMe2) that are terminally disubstituted and demonstrated enhanced anticancer activity in vitro and in vivo. The improved activity of these TSCs correlated with their ability to form stable copper complexes as well as induce paraptosis, a form of programmed but caspase-independent cell death, that is characterized by the formation of vesicles originating from the endoplasmic reticulum (ER). However, the molecular events behind paraptosis induction are still not fully elucidated. Consequently, the aim of this study was to investigate the molecular signaling behind paraptosis as well as the reasons behind the induction of this quite unknown form of cell death by TSCs.

A whole-genome gene expression analysis of cells treated with a terminally disubstituted TSC revealed an upregulation of thiol homeostasis-related genes, copper metabolism, and metallothionein genes as well as ER stress response genes. In addition, we found an upregulation of the copper-sensitive and thiol-containing protein disulfide isomerase (PDI), which was confirmed on protein level. In cell-free activity studies, PDI was indeed inhibited by terminally disubstituted TSCs, although only in form of their copper complexes. In agreement, removal of copper ions by specific chelators greatly reduced their anticancer activity as well as paraptotic potential in cell culture. This inhibition was hypothesized to be induced by a general disruption of the thiol redox homeostasis affecting also other responsive proteins and resulting in a more oxidative environment, especially in the ER. In confirmation, thiol-containing small molecules could reduce the compound’s anticancer activity in viability assays. Furthermore, glutathione as well as PDI were detected predominantly in their oxidized form in cells treated with terminally disubstituted TSCs.

Consequently, terminally disubstituted TSCs, which are characterized by higher anticancer activity, induce paraptosis due to their high copper complex stability. The formation of the complex results in the interaction with thiol-containing proteins and subsequently in the disruption of the thiol-redox homeostasis, which leads to paraptotic cell death. Overall this work shed light on the paraptotic cell death and will be of interest for future clinical development of anticancer TSCs, as paraptosis is hypothesized to overcome apoptosis-resistance of cancer cells.

Citation Format: Sonja Hager, Walter Berger, Christian R. Kowol, Eva A. Enyedy, Petra Heffeter. The role of protein disulfide isomerase and copper in the paraptotic cell death of clinically investigated anticancer thiosemicarbazones. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4901.

Copper-Catalyzed Glutathione Oxidation is Accelerated by the Anticancer Thiosemicarbazone Dp44mT and Further Boosted at Lower pH

Glutathione (GSH) is the most abundant thiol in mammalian cells and plays a crucial role in maintaining redox cellular homeostasis. The thiols of two GSH molecules can be oxidized to the disulfide GSSG. The cytosolic GSH/GSSG ratio is very high (>100), and its reduction can lead to apoptosis or necrosis, which are of interest in cancer research. Cu^II ions are very efficient oxidants of thiols, but with an excess of GSH, Cu^I_n(GS)_m clusters are formed, in which Cu^I is very slowly reoxidized by O₂ at pH 7.4 and even more slowly at lower pH. Here, the aerobic oxidation of GSH by Cu^II was investigated at different pH values in the presence of the anticancer thiosemicarbazone Dp44mT, which accumulates in lysosomes and induces lysosomal membrane permeabilization in a Cu-dependent manner. The results showed that Cu^II-Dp44mT catalyzes GSH oxidation faster than Cu^II alone at pH 7.4 and hence accelerates the production of very reactive hydroxyl radicals. Moreover, GSH oxidation and hydroxyl radical production by Cu^II-Dp44mT were accelerated at the acidic pH found in lysosomes. To decipher this unusually faster thiol oxidation at lower pH, density functional theory (DFT) calculations, electrochemical and spectroscopic studies were performed. The results suggest that the acceleration is due to the protonation of Cu^II-Dp44mT on the hydrazinic nitrogen, which favors the rate-limiting reduction step without subsequent dissociation of the Cu^I intermediate. Furthermore, preliminary biological studies in cell culture using the proton pump inhibitor bafilomycin A1 indicated that the lysosomal pH plays a role in the activity of Cu^II-Dp44mT.

Liposomal formulations of anticancer copper(II) thiosemicarbazone complexes

α-N-Heterocyclic thiosemicarbazones such as triapine and COTI-2 are currently investigated as anticancer therapeutics in clinical trials. However, triapine was widely inactive against solid tumor types. A likely explanation is the short plasma half-life time and fast metabolism. One promising approach to overcome these drawbacks is the encapsulation of the drug into nanoparticles (passive drug-targeting). In a previous work we showed that it was not possible to stably encapsulate free triapine into liposomes. Hence, in this manuscript we present the successful preparation of liposomal formulations of the copper(II) complexes of triapine and COTI-2. To this end, various drug-loading strategies were examined and the resulting liposomes were physico-chemically characterized. Especially for liposomal Cu-triapine, a decent encapsulation efficacy and a slow drug release behavior could be observed. In contrast, for COTI-2 and its copper(II) complex no stable loading could be achieved. Subsequent in vitro studies in different cell lines with liposomal Cu-triapine showed the expected strongly reduced cytotoxicity and DNA damage induction. Also in vivo distinctly higher copper plasma levels and a continuous release could be observed for the liposomal formulation compared to free Cu-triapine. Taken together, the here presented nanoformulation of Cu-triapine is an important step further to increase the plasma half-life time and tumor targeting properties of anticancer thiosemicarbazones.

Structure-Activity Relationships of Triple-Action Platinum(IV) Prodrugs with Albumin-Binding Properties and Immunomodulating Ligands

Chemotherapy with platinum complexes is essential for clinical anticancer therapy. However, due to side effects and drug resistance, further drug improvement is urgently needed. Herein, we report on triple-action platinum(IV) prodrugs, which, in addition to tumor targeting via maleimide-mediated albumin binding, release the immunomodulatory ligand 1-methyl-d-tryptophan (1-MDT). Unexpectedly, structure-activity relationship analysis showed that the mode of 1-MDT conjugation distinctly impacts the reducibility and thus activation of the prodrugs. This in turn affected ligand release, pharmacokinetic properties, efficiency of immunomodulation, and the anticancer activity in vitro and in a mouse model in vivo. Moreover, we could demonstrate that the design of albumin-targeted multi-modal prodrugs using platinum(IV) is a promising strategy to enhance the cellular uptake of bioactive ligands with low cell permeability (1-MDT) and to improve their selective delivery into the malignant tissue. This will allow tumor-specific anticancer therapy supported by a favorably tuned immune microenvironment.

Cancer Cell Resistance Against the Clinically Investigated Thiosemicarbazone COTI-2 Is Based on Formation of Intracellular Copper Complex Glutathione Adducts and ABCC1-Mediated Efflux

COTI-2 is a novel anticancer thiosemicarbazone in phase I clinical trial. However, the effects of metal complexation (a main characteristic of thiosemicarbazones) and acquired resistance mechanisms are widely unknown. Therefore, in this study, the copper and iron complexes of COTI-2 were synthesized and evaluated for their anticancer activity and impact on drug resistance in comparison to metal-free thiosemicarbazones. Investigations using Triapine-resistant SW480/Tria and newly established COTI-2-resistant SW480/Coti cells revealed distinct structure–activity relationships. SW480/Coti cells were found to overexpress ABCC1, and COTI-2 being a substrate for this efflux pump. This was unexpected, as ABCC1 has strong selectivity for glutathione adducts. The recognition by ABCC1 could be explained by the reduction kinetics of a ternary Cu-COTI-2 complex with glutathione. Thus, only thiosemicarbazones forming stable, nonreducible copper(II)-glutathione adducts are recognized and, in turn, effluxed by ABCC1. This reveals a crucial connection between copper complex chemistry, glutathione interaction, and the resistance profile of clinically relevant thiosemicarbazones.

High Copper Complex Stability and Slow Reduction Kinetics as Key Parameters for Improved Activity, Paraptosis Induction, and Impact on Drug-Resistant Cells of Anticancer Thiosemicarbazones

Aims: Due to their significant biological activity, thiosemicarbazones (TSCs) are promising candidates for anticancer therapy. In part, the efficacy of TSCs is linked to their ability to chelate essential metal ions such as copper and iron. Triapine, the best-studied anticancer TSC, has been tested clinically with promising results in hematological diseases. During the past few years, a novel subclass of TSCs with improved anticancer activity was found to induce paraptosis, a recently characterized form of cell death. The aim of this study was to identify structural and chemical properties associated with anticancer activity and paraptosis induction of TSCs. Results: When testing a panel of structurally related TSCs, compounds with nanomolar anticancer activity and paraptosis-inducing properties showed higher copper(II) complex solution stability and a slower reduction rate, which resulted in reduced redox activity. In contrast, TSCs with lower anticancer activity induced higher levels of superoxide that rapidly stimulated superoxide dismutase expression in treated cells, effectively protecting the cells from drug-induced redox stress. Innovation: Consequently, we hypothesize that in the case of close Triapine derivatives, intracellular reduction leads to rapid dissociation of intracellularly formed copper complexes. In contrast, TSCs characterized by highly stable, slowly reducible copper(II) complexes are able to reach new intracellular targets such as the endoplasmic reticulum-resident protein disulfide isomerase. Conclusion: The additional modes of actions observed with highly active TSC derivatives are based on intracellular formation of stable copper complexes, offering a new approach to combat (drug-resistant) cancer cells.

Abstract 1939: Improved activity and paraptosis-induction of anticancer thiosemicarbazones requires high copper(II) complex stability and slow reduction kinetics

Triapine, which is currently tested in a clinical phase III trial, is the best-studied thiosemicarbazone (TSC) for anticancer therapy. With regard to the mode of action, anticancer activity of TSCs is frequently linked to their ability to chelate essential metal ions such as copper and iron. As Triapine monotherapy showed promising results mainly against hematological diseases, novel TSC derivatives have been developed and clinically investigated for their activity against solid tumors. These novel TSCs belong to a subclass with enhanced anticancer activity in vitro and in vivo which were recently discovered to induce paraptosis, a form of programmed but caspase-independent cell death. As these TSCs are characterized by a up to 1000-fold higher activity in cell culture compared to Triapine, the aim of this study was to elucidate the mechanism of action as well as the underlying structural and chemical requirements of these effects.

For this purpose, a panel of structurally related Triapine derivatives was examined for anticancer activity (as metal-free ligand and copper(II) complex), paraptosis-inducing potential as well as solution stability and redox properties of their copper(II) complexes. Correlation studies between these chemical and biological properties revealed that the increased anticancer activity and paraptosis-inducing potential of the nanomolar active TSCs is related to a higher copper(II) complex solution stability and slower reduction rate. Unexpectedly, the TSCs with lower activity produced higher superoxide levels in a cell-free setting. This paradox could be explained by their lower copper(II) complex stability and increased readiness to be reduced, which resulted in a fast reduction of intracellular complexes and release of the metal-free ligand. Although this process resulted in the generation of superoxide, cell damage seemed to be prevented by rapid upregulation of the superoxide dismutase (in vitro and in vivo). In contrast, the copper complexes of the highly active TSCs are stable enough to reach intracellular targets such as the ER-resident protein disulfide isomerase, whose inhibition is crucial for paraptosis induction by TSCs.

In conclusion, copper complex stability is a crucial parameter of TSC activity, influencing the (intracellular) formation or dissociation of copper complexes. This intracellular stability of complexes, affects their mechanism of action as well as cell death induction. Overall, this study points out the importance of the redox parameters in order to understand and predict the TSC anticancer activity as well as their mechanism of action and, thereby, will pave the way for the development of improved anticancer agents.

Citation Format: Sonja Hager, Veronika F. Pape, Vivien Pósa, Bianca Montsch, Lukas Uhlik, Gergely Szakàcs, Szilárd Tóth, Nikolett Jabronka, Bernhard K. Keppler, Walter Berger, Christian R. Kowol, Éva A. Enyedy, Petra Heffeter. Improved activity and paraptosis-induction of anticancer thiosemicarbazones requires high copper(II) complex stability and slow reduction kinetics [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1939.

Understanding the metabolism of the anticancer drug Triapine: electrochemical oxidation, microsomal incubation and in vivo analysis using LC-HRMS

α-N-Heterocyclic thiosemicarbazones are among the most promising ribonucleotide reductase inhibitors identified so far. Triapine, the most prominent representative of this class of substances, has been investigated in multiple phase I and II clinical trials. With regard to clinical practice, Triapine showed activity against hematological diseases, but ineffectiveness against a variety of solid tumors. However, the reasons are still vague and the amount of ADME (absorption, distribution, metabolism and excretion) data for Triapine available in the literature is very limited. Therefore, different analytical tools were used to investigate the metabolism of Triapine including electrochemical oxidations, liver microsomes and in vivo samples from mice. The main metabolic reactions, observed by all three methods, were dehydrogenation and hydroxylations, confirming that electrochemistry, as a purely instrumental approach, can be applied for the simulation of metabolic pathways. The dehydrogenated metabolite M1 was identified as a thiadiazole ring-closed oxidation product of Triapine. From a biological point of view, M1, as a key metabolite, is of interest since the crucial chemical property of α-N-heterocyclic thiosemicarbazones to bind metal ions is lost and cytotoxicity studies showed no anticancer activity of M1. The in vivo data of the urine samples revealed very high levels of the metabolites and Triapine itself already 15 min after treatment. This clearly indicates that Triapine is rapidly metabolised and excreted, which represents an important step forward to understand the possible reason for the inefficiency of Triapine against solid tumors.

The thiosemicarbazone Me2NNMe2 induces paraptosis by disrupting the ER thiol redox homeostasis based on protein disulfide isomerase inhibition

Due to their high biological activity, thiosemicarbazones have been developed for treatment of diverse diseases, including cancer, resulting in multiple clinical trials especially of the lead compound Triapine. During the last years, a novel subclass of anticancer thiosemicarbazones has attracted substantial interest based on their enhanced cytotoxic activity. Increasing evidence suggests that the double-dimethylated Triapine derivative Me₂NNMe₂ differs from Triapine not only in its efficacy but also in its mode of action. Here we show that Me₂NNMe₂- (but not Triapine)-treated cancer cells exhibit all hallmarks of paraptotic cell death including, besides the appearance of endoplasmic reticulum (ER)-derived vesicles, also mitochondrial swelling and caspase-independent cell death via the MAPK signaling pathway. Subsequently, we uncover that the copper complex of Me₂NNMe₂ (a supposed intracellular metabolite) inhibits the ER-resident protein disulfide isomerase, resulting in a specific form of ER stress based on disruption of the Ca²⁺ and ER thiol redox homeostasis. Our findings indicate that compounds like Me₂NNMe₂ are of interest especially for the treatment of apoptosis-resistant cancer and provide new insights into mechanisms underlying drug-induced paraptosis.

Flexed-knee gait in children with cerebral palsy

Aims

The purpose of this study was to evaluate the long-term outcome of adolescents with cerebral palsy who have undergone single-event multilevel surgery for a flexed-knee gait, followed into young adulthood using 3D motion analysis.

Patients and Methods

A total of 59 young adults with spastic cerebral palsy, with a mean age of 26 years (sd 3), were enrolled into the study in which their gait was compared with an evaluation that had taken place a mean of 12 years (sd 2) previously. At their visits during adolescence, the children walked with excessive flexion of the knee at initial contact and surgical or therapeutic interventions were not controlled between visits.

Results

Based on the change in flexed-knee gait over approximately ten years, improvements were seen in increased Gait Deviation Index (p < 0.001) and decreased flexion of the knee at initial contact (p < 0.001). Greater popliteal angle (p < 0.001), reduced Gross Motor Function Measure section D (p = 0.006), and reduced speed of gait (p = 0.007) suggested a mild decline in function. Quality-of-life measures showed that these patients fell within normal limits compared with typical young adults in areas other than physical function.

Conclusion

While some small significant changes were noted, little clinically significant change was seen in function and gait, with gross motor function maintained between adolescence and young adulthood. Cite this article: Bone Joint J 2018;100-B:549–56.

Quantum Dot Based Luminescent Nanoprobes for Sigma-2 Receptor Imaging

The increasing importance of sigma-2 receptor as target for the diagnosis and therapy of tumors paves the way for the development of innovative optically traceable fluorescent probes as tumor cell contrast and therapeutic agents. Here, a novel hybrid organic-inorganic nanostructure is developed by combining the superior fluorescent properties of inorganic quantum dots (QDs), coated with a hydrophilic silica shell (QD@SiO₂ NPs), the versatility of the silica shell, and the high selectivity for sigma-2 receptor of the two synthetic ligands, namely, the 6-[(6-aminohexyl)oxy]-2-(3-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)propyl)-3,4-dihydroisoquinolin-1(2H)-one (MLP66) and 6-[1-[3-(4-cyclohexylpiperazin-1-yl)propyl]-1,2,3,4-tetrahydronaphthalen-5-yloxy]hexylamine (TA6). The proposed nanostructures represent a challenging alternative to all previously studied organic small fluorescent molecules, based on the same sigma-2 receptor affinity moieties. Flow cytometry and confocal fluorescence microscopy experiments, respectively, on fixed and living cancerous MCF7 cells, which overexpress the sigma-2 receptor, prove the ability of functionalized (QD@SiO₂-TA6 and QD@SiO₂-MLP66) NPs to be internalized and demonstrate their affinity to the sigma-2 receptor, ultimately validating the targeting properties conveyed to the NPs by sigma-2 ligand conjugation. The presented QD-based nanoprobes possess a great potential as in vitro selective sigma-2 receptor imaging agent and, consequently, could provide a significant impact to future theranostic applications.

Multifunctional αvβ6 Integrin-Specific Peptide-Pt(IV) Conjugates for Cancer Cell Targeting

Increasing the specificity of cancer therapy, and thereby decreasing damage to normal cells, requires targeting to cancer-cell specific features. The α_vβ₆ integrin is a receptor involved in cell adhesion and is frequently up-regulated in cancer cells compared to normal cells. We have selected a peptide ligand reported to bind specifically to the β₆ integrin and have synthesized a suite of multispecific molecules to explore the potential for targeting of cancer cells. A combination of solid-phase peptide synthesis and chemoselective ligations was used to synthesize multifunctional molecules composed of integrin-targeting peptides, cytotoxic platinum(IV) prodrugs, and fluorescent or affinity probes joined with flexible linkers. The modular synthesis approach facilitates the construction of peptide-drug conjugates with various valencies and properties in a convergent manner. The binding and specificity of the multifunctional peptide conjugates were investigated using a cell line transfected with the β₆ integrin and fluorescence microscopy. This versatile and highly controlled approach to synthesizing labeled peptide-drug conjugates has the potential to target potent cytotoxic drugs specifically to cancer cells, reducing the doses required for effective treatment.

EGFR-targeting peptide-coupled platinum(IV) complexes

The high mortality rate of lung cancer patients and the frequent occurrence of side effects during cancer therapy demonstrate the need for more selective and targeted drugs. An important and well-established target for lung cancer treatment is the occasionally mutated epidermal growth factor receptor (EGFR). As platinum(II) drugs are still the most important therapeutics against lung cancer, we synthesized in this study the first platinum(IV) complexes coupled to the EGFR-targeting peptide LARLLT (and the shuffled RTALLL as reference). Notably, HPLC–MS measurements revealed two different peaks with the same molecular mass, which turned out to be a transcyclization reaction in the linker between maleimide and the coupled cysteine moiety. With regard to the EGFR specificity, subsequent biological investigations (3-day viability, 14-day clonogenic assays and platinum uptake) on four different cell lines with different verified EGFR expression levels were performed. Unexpectedly, the results showed neither an enhanced activity nor an EGFR expression-dependent uptake of our new compounds. Consequently, fluorophore-coupled peptides were synthesized to re-evaluate the targeting ability of LARLLT itself. However, also with these molecules, flow cytometry measurements showed no correlation of drug uptake with the EGFR expression levels. Taken together, we successfully synthesized the first platinum(IV) complexes coupled to an EGFR-targeting peptide; however, the biological investigations revealed that LARLLT is not an appropriate peptide for enhancing the specific uptake of small-molecule drugs into EGFR-overexpressing cancer cells.

Loss of phosphodiesterase 4D mediates acquired triapine resistance via Epac-Rap1-Integrin signaling

Triapine, an anticancer thiosemicarbazone, is currently under clinical investigation. Whereas promising results were obtained in hematological diseases, trials in solid tumors widely failed. To understand mechanisms causing triapine insensitivity, we have analysed genomic alterations in a triapine-resistant SW480 subline (SW480/tria). Only one distinct genomic loss was observed specifically in SW480/tria cells affecting the phosphodiesterase 4D (PDE4D) gene locus. Accordingly, pharmacological inhibition of PDE4D resulted in significant triapine resistance in SW480 cells. Hence, we concluded that enhanced cyclic AMP levels might confer protection against triapine. Indeed, hyperactivation of both major downstream pathways, namely the protein kinase A (PKA)-cAMP response element-binding protein (Creb) and the exchange protein activated by cAMP (Epac)-Ras-related protein 1 (Rap1) signaling axes, was observed in SW480/tria cells. Unexpectedly, inhibition of PKA did not re-sensitize SW480/tria cells against triapine. In contrast, Epac activation resulted in distinct triapine resistance in SW480 cells. Conversely, knock-down of Epac expression and pharmacological inhibition of Rap1 re-sensitized SW480/tria cells against triapine. Rap1 is a well-known regulator of integrins. Accordingly, SW480/tria cells displayed enhanced plasma membrane expression of several integrin subunits, enhanced adhesion especially to RGD-containing matrix components, and bolstered activation/expression of the integrin downstream effectors Src and RhoA/Rac. Accordingly, integrin and Src inhibition resulted in potent triapine re-sensitization especially of SW480/tria cells. In summary, we describe for the first time integrin activation based on cAMP-Epac-Rap1 signaling as acquired drug resistance mechanism. combinations of triapine with inhibitors of several steps in this resistance cascade might be feasible strategies to overcome triapine insensitivity of solid tumors.

Sigma-2 receptor and progesterone receptor membrane component 1 (PGRMC1) are two different proteins: Proofs by fluorescent labeling and binding of sigma-2 receptor ligands to PGRMC1

A controversial relationship between sigma-2 and progesterone receptor membrane component 1 (PGRMC1) proteins, both representing promising targets for the therapy and diagnosis of tumors, exists since 2011, when the sigma-2 receptor was reported to be identical to PGRMC1. Because a misidentification of these proteins will lead to biased future research hampering the possible diagnostic and therapeutic exploitation of the two targets, there is the need to solve the debate on their identity. With this aim, we have herein investigated uptake and distribution of structurally different fluorescent sigma-2 receptor ligands by flow cytometry and confocal microscopy in MCF7 cells, where together with intrinsic sigma-2 receptors, PGRMC1 was constitutively present or alternatively silenced or overexpressed. HCT116 cells, with constitutive or silenced PGRMC1, were also studied. These experiments showed that the fluorescent sigma-2 ligands bind to their receptor irrespective of PGRMC1 expression. Furthermore, isothermal titration calorimetry was conducted to examine if DTG and PB28, two structurally distinct nanomolar affinity sigma-2 ligands, bind to purified PGRMC1 proteins that have recently been revealed to form both apo-monomeric and heme-mediated dimeric forms. While no binding to apo-PGRMC1 monomer was detected, a micromolar affinity to heme-mediated dimerized PGRMC1 was demonstrated in DTG but not in PB28. The current data provide evidence that sigma-2 receptor and PGRMC1 are not identical, paving the pathway for future unbiased research in which these two attractive targets are treated as different proteins while the identification of the true sigma-2 protein further needs to be pursued.

Impact of Stepwise NH2-Methylation of Triapine on the Physicochemical Properties, Anticancer Activity, and Resistance Circumvention

One of the most promising classes of iron chelators are α-N-heterocyclic thiosemicarbazones with Triapine as the most prominent representative. In several clinical trials Triapine showed anticancer activity against hematological diseases, however, studies on solid tumors failed due to widely unknown reasons. Some years ago, it was recognized that “terminal dimethylation” of thiosemicarbazones can lead to a more than 100-fold increased activity, probably due to interactions with cellular copper depots. To better understand the structural requirements for the switch to nanomolar cytotoxicity, we systematically synthesized all eight possible N-methylated derivatives of Triapine and investigated their potential against Triapine-sensitive as well as -resistant cell lines. While only the “completely” methylated compound exerted nanomolar activity, the data revealed that all compounds with at least one N-dimethylation were not affected by acquired Triapine resistance. In addition, these compounds were highly synergistic with copper treatment accompanied by induction of reactive oxygen species and massive necrotic cell death.

Anti-tumour activity of platinum compounds in advanced prostate cancer-a systematic literature review

BACKGROUND

For men with advanced castration-resistant prostate cancer (CRPC), several treatment options are available, including androgen receptor (AR) pathway inhibitors (abiraterone acetate, enzalutamide), taxanes (docetaxel, cabazitaxel) and the radionuclide (radium-223). However, cross-resistance is a clinically relevant problem. Platinum compounds have been tested in a number of clinical trials in molecularly unselected prostate cancer patients. Advances in CRPC molecular profiling have shown that a significant proportion of patients harbour DNA repair defects, which may serve as predictive markers for sensitivity to platinum agents.

OBJECTIVE

To systematically identify and analyse clinical trials that have evaluated platinum agents in advanced prostate cancer patients.

METHODS

PubMed was searched to identify published clinical trials of platinum agents in advanced prostate cancer. The PRIMSA statement was followed for the systematic review process. Identified trials are analysed for study design, statistical plan, assessments of anti-tumour activity and the potential value of predictive biomarkers.

RESULTS

A total of 163 references were identified by the literature search and 72 publications that met the selection criteria were included in this review; of these 33 used carboplatin, 27 cisplatin, 6 satraplatin, 4 oxaliplatin and 2 other platinum compounds. Overall, anti-tumour activity varies in the range of 10%-40% for objective response and 20%-70% for PSA decline ≥50%. Response seemed highest for the combinations of carboplatin with taxanes or oxaliplatin with gemcitabine. The interpretation of the clinical data is limited by differences in response criteria used and patient populations studied.

CONCLUSION

Platinum compounds have moderate anti-tumour activity in molecularly unselected patients with advanced prostate cancer. Translational evidence of DNA repair deficiency should be leveraged in future studies to select prostate cancer patients most likely to benefit from platinum-based therapy.

A randomized phase II study of the telomerase inhibitor imetelstat as maintenance therapy for advanced non-small-cell lung cancer

BACKGROUND

Continuation or 'switch' maintenance therapy is commonly used in patients with advancd non-small-cell lung cancer (NSCLC). Here, we evaluated the efficacy of the telomerase inhibitor, imetelstat, as switch maintenance therapy in patients with advanced NSCLC.

PATIENTS AND METHODS

The primary end point of this open-label, randomized phase II study was progression-free survival (PFS). Patients with non-progressive, advanced NSCLC after platinum-based doublet (first-line) chemotherapy (with or without bevacizumab), any histology, with Eastern Cooperative Oncology Group performance status 0-1 were eligible. Randomization was 2 : 1 in favor of imetelstat, administered at 9.4 mg/kg on days 1 and 8 of a 21-day cycle, or observation. Telomere length (TL) biomarker exploratory analysis was carried out in tumor tissue by quantitative PCR (qPCR) and telomerase fluorescence in situ hybridization.

RESULTS

Of 116 patients enrolled, 114 were evaluable. Grade 3/4 neutropenia and thrombocytopenia were more frequent with imetelstat. Median PFS was 2.8 and 2.6 months for imetelstat-treated versus control [hazard ratio (HR) = 0.844; 95% CI 0.54-1.31; P = 0.446]. Median survival time favored imetelstat (14.3 versus 11.5 months), although not significantly (HR = 0.68; 95% CI 0.41-1.12; P = 0.129). Exploratory analysis demonstrated a trend toward longer median PFS (HR = 0.43; 95% CI 0.14-1.3; P = 0.124) and overall survival (OS; HR = 0.41; 95% CI 0.11-1.46; P = 0.155) in imetelstat-treated patients with short TL, but no improvement in median PFS and OS in patients with long TL (HR = 0.86; 95% CI 0.39-1.88; and HR = 0.51; 95% CI 0.2-1.28; P = 0.145).

CONCLUSIONS

Maintenance imetelstat failed to improve PFS in advanced NSCLC patients responding to first-line therapy. There was a trend toward a improvement in median PFS and OS in patients with short TL. Short TL as a predictive biomarker will require further investigation for the clinical development of imetelstat.

New non-invasive approaches for the diagnosis of cardiomyopathy: magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) permits a detailed look at the myocardium in patients with recent onset heart failure. Late-enhancement CMR provides information that is similar to that obtained by the naked eye of a pathologist. Myocardial scarring is endocardial in myocardial infarction, but it is epicardial in myocarditis and intramyocardial in hypertrophic cardiomyopathy. Thus, the distinction between these entities is possible by depicting scar via late-enhancement CMR and observing myocardial function by cine magnetic resonance imaging. Moreover, non-invasive follow-up--and hence observation of the healing or remodelling process--can be achieved using CMR. New CMR pulse sequences also permit depiction of myocardial oedema, which may occur early in patients with myocarditis and may be the only sign of the disease in the absence of necrosis. It is anticipated that cardiac MRI will become a standard diagnostic technique in patients with new onset of heart failure, left-ventricular hypertrophy or clinical symptoms suggestive of myocarditis.

Lack of evidence for local immune activity in oral hairy leukoplakia and oral wart lesions

BACKGROUND

Oral warts, caused by human papillomavirus (HPV), and oral hairy leukoplakia (OHL) caused by Epstein-Barr virus (EBV), are common oral manifestations in HIV-infected persons. Although both conditions occur most often with reduced blood CD4+ T-cell numbers, oral warts and OHL rarely occur simultaneously, suggesting that dysfunctions in other secondary local immune parameters are also involved. The present study evaluated tissue-associated proinflammatory and T-helper cytokine and chemokine mRNA expression and the presence of T cells in each lesion.

METHODS

Biopsies were taken from lesion-positive and adjacent lesion-negative sites of HIV+ persons with oral warts or OHL and lesion-negative sites from HIV+ persons who were oral HPV or EBV DNA-positive (matched controls). Cytokine/chemokine mRNA expression was quantified by real-time polymerase chain reaction. CD3, CD4, and CD8 cells were identified by immunohistochemistry.

RESULTS

No differences were detected in tissue-associated cytokine/chemokine mRNA expression in warts or OHL when compared to lesion-negative sites. Immunohistochemical analysis of T cells showed CD8+ cells exclusively, but few cells were present in either lesion. No differences were detected between lesion-positive and -negative control sites of each pathologic condition.

CONCLUSION

Little evidence was found for local immune reactivity to either oral warts and OHL, suggesting that CD4+ T cells are a primary host defense against both oral warts and OHL, but with nonimmune factors potentially responsible for the divergent prevalence of each.

Use of traditional drugs in a hospital of Chinese medicine in Germany

The frequency of use of traditional Chinese drugs was investigated in relation to Western and Chinese diagnostic classifications in a hospital for traditional Chinese medicine in Germany. All 1597 in-patients treated in the hospital between February 1992 and August 1993 entered a prospective observational study. About two thirds of the patients suffered from chronic pain syndromes, the most frequent single diagnosis being migraine (n=244). All patients were treated with at least one of four Chinese therapies (traditional Chinese drugs, acupuncture, Tuina-massage, Qi-gong). 95.1% of all patients received traditional Chinese drug treatment, prescribed in complex prescriptions including 3 to 12 single drugs from a total of 305. Drug patterns prescribed to patients with the same Western diagnosis tended to be similar, but could differ strongly for single drugs in subgroups with distinct Chinese diagnoses. Studies evaluating traditional Chinese treatment strategies in patients classified according to Western nosology should take into account possible diagnostic differences according to Chinese nosology. The development of a reliable coding system for Chinese diagnostic classifications is a precondition for further cross-cultural studies.

Use of traditional drugs in a hospital of Chinese medicine in Germany

The frequency of use of traditional Chinese drugs was investigated in relation to Western and Chinese diagnostic classifications in a hospital for traditional Chinese medicine in Germany. All 1597 in-patients treated in the hospital between February 1992 and August 1993 entered a prospective observational study. About two thirds of the patients suffered from chronic pain syndromes, the most frequent single diagnosis being migraine (n=244). All patients were treated with at least one of four Chinese therapies (traditional Chinese drugs, acupuncture, Tuina-massage, Qi-gong). 95.1% of all patients received traditional Chinese drug treatment, prescribed in complex prescriptions including 3 to 12 single drugs from a total of 305. Drug patterns prescribed to patients with the same Western diagnosis tended to be similar, but could differ strongly for single drugs in subgroups with distinct Chinese diagnoses. Studies evaluating traditional Chinese treatment strategies in patients classified according to Western nosology should take into account possible diagnostic differences according to Chinese nosology. The development of a reliable coding system for Chinese diagnostic classifications is a precondition for further cross-cultural studies.

Acupuncture versus placebo versus sumatriptan for early treatment of migraine attacks: a randomized controlled trial

OBJECTIVES

To investigate whether acupuncture is superior to placebo and equivalent to sumatriptan for the early treatment of an acute migraine attack.

DESIGN

Randomized, partly double-blind (sumatriptan versus placebo) trial.

SETTING

Two hospitals in Germany (one specialized in traditional Chinese medicine and one in the treatment of headache).

SUBJECTS

A total of 179 migraineurs experiencing the first symptoms of a developing migraine attack.

INTERVENTIONS

Traditional Chinese acupuncture, sumatriptan (6 mg subcutaneously) or placebo injection.

MAIN OUTCOME MEASURE

Number of patients in whom a full migraine attack (defined as severe migraine headache) within 48 h was prevented. In patients who developed a migraine attack in spite of early treatment, acupuncture and sumatriptan were applied a second time, whilst patients initially randomized to placebo received sumatriptan.

RESULTS

A full migraine attack was prevented in 21 of 60 (35%) patients receiving acupuncture, 21 of 58 (36%) patients receiving sumatriptan and 11 of 61 (18%) patients receiving placebo (relative risk of having a full attack 0.79 (95% CI, 0.64-0.99) for acupuncture versus placebo, and 0.78 (95% CI, 0.62-0.98) for sumatriptan versus placebo). Response to the second intervention in patients who developed a full attack was better with sumatriptan (17/31 patients who received sumatriptan twice and 37/46 patients who had had placebo first) than with acupuncture (4/31). The number of patients reporting side-effects was 14 in the acupuncture group, 23 in the sumatriptan group and 10 in the placebo group.

CONCLUSIONS

In this trial acupuncture and sumatriptan were more effective than a placebo injection in the early treatment of an acute migraine attack. When an attack could not be prevented, sumatriptan was more effective than acupuncture at relieving headache.

Th1/Th2 cytokine profiles in saliva of HIV-positive smokers with oropharyngeal candidiasis

Oropharyngeal candidiasis (OPC) is a common opportunistic infection among HIV-positive individuals and often correlates with a CD4 cell number < 200 cells/microl. This study further examined the association of smoking and OPC in HIV-positive persons. A strong association between smoking and OPC was seen in HIV-positive individuals with > or =200 CD4 cells/microl. In HIV-positive persons with > or =200 CD4 cells/microl, OPC+ smokers had lower gamma-interferon (IFN-gamma) concentrations and a trend toward higher interleukin (IL)-4 concentrations in whole saliva compared to OPC- persons with > or =200 CD4 cells/microl, a cytokine profile consistent with that observed in HIV+OPC+ persons with < 200 CD4 cells/microl. These results suggest that premature OPC in HIV-positive smokers is associated with altered oral host defence mechanisms that cannot be overcome by levels of systemic CD4 cells that are otherwise sufficient to protect against OPC.

Candida-specific systemic cell-mediated immune reactivities in human immunodeficiency virus-positive persons with mucosal candidiasis

Oropharyngeal candidiasis (OPC), as opposed to vulvovaginal candidiasis (VVC), is a common opportunistic infection in human immunodeficiency virus (HIV)-positive persons that correlates with reduced CD4 T cell counts. Although cell-mediated immunity (CMI) by CD4 Th1-type cells is considered to be the predominant host defense against mucosal candidiasis, the immune factors associated with susceptibility to OPC in HIV-positive persons are not well understood. This study investigated Candida-specific systemic CMI in HIV-positive persons with OPC and/or VVC. Reductions in delayed skin test reactivity to Candida antigen were observed in HIV-positive persons with CD4 cell counts <200 cells/microL, irrespective of the presence of mucosal infection. Likewise, despite the correlate of OPC with reduced CD4 cell counts in HIV-positive persons, differences in Candida-specific peripheral blood mononuclear cell proliferation and Th1/Th2 cytokine production between HIV-positive and HIV-negative persons were not consistent in a manner to suggest that deficiencies in Candida-specific systemic CMI account solely for the susceptibility to OPC.

Photocatalytic oxidation of gaseous chlorinated organics over titanium dioxide

The photocatalytic oxidation of high levels of volatile chlorinated organic compounds in gas phase has been studied using a specially designed photoreactor. The influence of light intensity, initial water vapour concentration, temperature, inlet contaminant concentration and flow rate on destruction efficiency has been investigated. The performance of the titanium catalyst was strongly affected by the presence of water in the air stream. Experiments have been most successfully conducted at room temperature, low initial contaminant concentrations, low flow rates and high light intensities. Several by-products have been detected performing photocatalytic degradation of trichloroethylene (TCE) and tetrachloroethylene (PCE). No catalyst deactivation was observed.

Monitoring of liver enzymes in patients treated with traditional Chinese drugs

BACKGROUND

Use of traditional Chinese drug treatment is widespread. While cases of hepatotoxic effects have been reported, little is known about the frequency of such effects.

OBJECTIVES

To investigate the frequency, magnitude and course of liver enzyme elevations in patients treated with traditional Chinese drugs.

DESIGN

Retrospective study.

SETTING

Hospital for traditional Chinese medicine in Germany.

PATIENTS

All 1507 patients admitted for inpatient treatment between February 1994 and July 1995.

MAIN OUTCOME MEASURE

Number of patients who presented at discharge with a more than 2-fold elevation of alanine amino transferase (ALT) levels (over maximum normal values or elevated admission values).

RESULTS

A more than 2-fold elevation of ALT values was observed in 14 patients (0.9%). In 13 cases a causal relationship with Chinese drug therapy seemed possible and, for one patient, likely. However, all patients were also on non-Chinese drug treatment. Follow-up values of ALT within 8 weeks after discharge were normal in 11 patients (six of them had continued to take traditional Chinese drugs) and close to normal in the remaining three. In five patients there were indications for previous liver damage.

CONCLUSIONS

In the population and setting studied, clinically relevant liver enzyme elevations occurred in about 1/100 patients treated with traditional Chinese drugs.

The Nursing Research Initiative for Scotland

The Nursing Research Initiative for Scotland (NRIS) was established at the end of 1994, one of seven research units core funded by the Chief Scientist Office (CSO) of the Scottish Office. It is a national unit, so although its central base is in Glasgow, it works with nurses, other direct care staff and academics throughout Scotland.

Heterogeneous photocatalytic oxidation of organics for air purification by near UV irradiated titanium dioxide

The photocatalytic degradation of high concentrations of various organic pollutants (acetone, 2-propanol and toluene) in dry and humid air streams was carried out using a specially designed photoreactor based on the UV-TiO2 principle. The influence of several parameters which control the destruction efficiency (flow rate, initial contaminant and water vapour concentration, temperature and light intensity) has been studied. The conversion was maximal at room temperature, low flow rates and low initial contaminant concentrations. The presence of water in the inlet stream strongly affected the performance of the catalyst. The primary oxidation product of 2-propanol was acetone.

Systematic clinical auditing in complementary medicine: rationale, concept, and a pilot study

A scientific evaluation of complementary medical practices commonly used in healthcare is urgently required. Although randomized clinical trials are the primary tool for such an evaluation, for a number of conceptual and pragmatic reasons, they should not be the only tool. The authors propose systematic clinical auditing as a concept to (1) provide information on the "epidemiology" of complementary medical practices, (2) make the processes used in the daily practice of these complementary methods clearly intelligible, and (3) give a preliminary estimation of outcomes. Systematic clinical auditing uses mainly observational studies of large samples of patients. A pilot study was conducted to investigate the feasibility of using a systematic clinical audit in a hospital for traditional Chinese medicine in Germany. All 1597 patients admitted between February 1, 1992, and August 31, 1993, were included in the study. Patients' characteristics, diagnoses, and preventive and therapeutic interventions were recorded, and patients were asked to rate the intensity of their main complaints (on scale of 1 to 10) at admission; at discharge; and at 2, 6, and 12 months after admission. About two thirds of all patients had chronic pain complaints; the most common diagnosis was migraine (n = 244). Nearly all patients received acupuncture and Chinese herbal therapy; 61% received tuina massages, and 16% received qigong. The mean intensity of main complaints was 7.0 (2.0, SD) at admission, 4.6 (2.4) at discharge, and 5.5 (2.7) 12 months after admission. In the authors' opinion, systematic clinical auditing is a valuable tool for collecting basic information on structural characteristics, processes, and outcomes in complementary medicine and for determining representative and relevant questions for future randomized clinical trials.

Insulin stimulates fatty acid acylation of adipocyte proteins

Isolated rat adipocytes were incubated with [3H]palmitate in the presence or absence of insulin. Insulin caused marked (20-fold), rapid (T1/2 approximately 15 min), and concentration-dependent labeling of an 80 kilodalton protein. The insulin concentration producing half-maximal labeling was 0.4 ng/ml. The label was removed from the protein by treatment with hydroxylamine indicating the fatty acid was linked to the protein via an oxyester bond. Label removed from the protein co-eluted with palmitate standard by high-performance liquid chromatography. In summary, adipocyte proteins are subject to acylation by exogenous long-chain fatty acids and this process is stimulated by insulin.

Immunologically cross-reactive and redox-competent cytochrome b6/f-complexes in the chlorophyll-free plasma membrane of cyanobacteria

Plasma and thylakoid membranes were separated and purified from cell-free extracts of the cyanobacteria Anacystis nidulans, Synechocystis 6714, Anabaena variabilis and Nostoc sp. strain Mac. Immunoblots of the membrane proteins using antisera raised against subunits I-IV of the chloroplast b6/f-complex gave evidence for the presence of a homologous complex in both plasma and thylakoid membranes from the four species of cyanobacteria investigated. Both plasma and thylakoid membranes catalyzed the electron transfer from (exogenous) plastoquinol-9 and NADH to horse heart ferricytochrome c. However, while with plasma membranes these reactions were severely inhibited by low concentrations of antimycin A and rotenone, respectively, the inhibitors were without major effect on thylakoid membranes. The results will be discussed in terms of a possible similarity (analogy and/or homology?) of cyanobacterial plasma membranes to the inner mitochondrial membrane.

The dilemma of less than 500 grams birth: epidemiologic considerations

The reporting practice of perinatal data of less than 500 gm is widely inconsistent. This is due mainly to the differences in reporting requirements and ambiguity in the definition of live births, stillbirths and abortions. To evaluate the magnitude a birthweight of less than 500 gm has on a regional perinatal network's vital statistics, we studied race and weight specific data from a cohort of 48,096 births over a 2-year period. One hundred and ten (0.23%) births weighed less than 500 gm, 60 of them were live births occurring at a mean gestation of 22.3 +/- 3 weeks, all of whom died. Blacks had the highest rates for other adverse perinatal outcome measures as well as significantly higher incidence of birthweights less than 500 gm (0.3%), compared to whites and Hispanics, 0.17 and 0.21%, respectively (P less than 0.001). Although they constituted a small fraction of the total births in all ethnic groups, infants weighing less than 500 gm accounted for a significant proportion, 18 and 21%, of the perinatal and neonatal mortality rates (PMR and NMR). These proportions were much higher in the black subgroup. We conclude that major discrepancies in reporting of vital data concerning these infants could affect the vital rates significantly. The effect is not uniform, since the subsets with a high incidence of infants weighing less than 500 gm will have far more variations. This must be considered when comparative epidemiologic studies of perinatal outcome are carried out.