The RelB-BLNK Axis Determines Cellular Response to a Novel Redox-Active Agent Betamethasone during Radiation Therapy in Prostate Cancer

Aberrant levels of reactive oxygen species (ROS) are potential mechanisms that contribute to both cancer therapy efficacy and the side effects of cancer treatment. Upregulation of the non-canonical redox-sensitive NF-kB family member, RelB, confers radioresistance in prostate cancer (PCa). We screened FDA-approved compounds and identified betamethasone (BET) as a drug that increases hydrogen peroxide levels in vitro and protects non-PCa tissues/cells while also enhancing radiation killing of PCa tissues/cells, both in vitro and in vivo. Significantly, BET increases ROS levels and exerts different effects on RelB expression in normal cells and PCa cells. BET induces protein expression of RelB and RelB target genes, including the primary antioxidant enzyme, manganese superoxide dismutase (MnSOD), in normal cells, while it suppresses protein expression of RelB and MnSOD in LNCaP cells and PC3 cells. RNA sequencing analysis identifies B-cell linker protein (BLNK) as a novel RelB complementary partner that BET differentially regulates in normal cells and PCa cells. RelB and BLNK are upregulated and correlate with the aggressiveness of PCa in human samples. The RelB-BLNK axis translocates to the nuclear compartment to activate MnSOD protein expression. BET promotes the RelB-BLNK axis in normal cells but suppresses the RelB-BLNK axis in PCa cells. Targeted disruptions of RelB-BLNK expressions mitigate the radioprotective effect of BET on normal cells and the radiosensitizing effect of BET on PCa cells. Our study identified a novel RelB complementary partner and reveals a complex redox-mediated mechanism showing that the RelB-BLNK axis, at least in part, triggers differential responses to the redox-active agent BET by stimulating adaptive responses in normal cells but pushing PCa cells into oxidative stress overload.

Abstract A41: Novel mithramycin analogues with improved pharmacologic profile and efficacy in ETS transcription factor-driven tumors

Introduction: Chromosomal translocations of ETS family transcription factors (TF) are found in Ewing sarcoma, prostate cancer, and leukemia and lead to expression of aberrant ETS transcription factors driving tumorigenesis. Mithramycin (MTM) inhibits EWS-FLI1, the most common ETS-related TFs in Ewing sarcoma through interference at its DNA binding sites on promoters. However, MTM has a narrow therapeutic window marked by severe liver and hematologic toxicities and poor pharmacokinetic (PK) properties, as demonstrated recently in a pediatric clinical trial with Ewing sarcoma patients. Here, we sought to develop analogues with specificity toward ETS family TFs and improved pharmacologic properties.

Methods: Guided by crystal structures of MTM/DNA/ETS, we used semisynthetic approaches to prepare a library of analogs by substitution on the 3-side chain of MTM-SA and MTM (analogs). To select analogs with specific activity toward cells with ETS-related chromosomal translocations, analog cytotoxicity was determined in TC32 cells before and after EWS-FLI1 silencing. To confirm selectivity, analogs were tested in a panel of Ewing sarcoma cell lines (n=8) expressing EWS-ETS translocations and compared to a panel of non-Ewing cell lines (n=9) that do not express these translocations. CETSA, FRET, and luciferase reporter assays were used to evaluate interactions with EWS-FLI1 and SP1 proteins and gene promoter regions they bind. Inhibition of select transcriptionally regulated genes was determined by qRT-PCR and immunoblotting. Select analogs were tested in vivo to assess PK in mice and primates, identify the maximum tolerated dose (MTD), and determine dose-dependent efficacy in mouse xenograft models.

Results: MTM analogs had higher GI50 in silenced EWS-FLI1 cells and > 10-fold lower GI50 in ETS-dependent cell lines vs. non-ETS dependent cancer cells, as compared to ~3-fold for MTM. Target engagement was demonstrated in dose-dependent manner using a luciferase reporter TC32 cell line under control of the NR0B1 promoter, which is regulated by EWS-FLI1, and CETSA experiments showed increased physical interaction of the analogs with EWS-FLI1 as compared to MTM. Treatment with MTM and analogs produced comparable dose-dependent displacement of an ETS DNA binding domain from GGAA (microsatellite-like) DNA fragments as demonstrated by FRET. Exposure to analogs led to concentration-dependent downregulation of EWS-FLI1 and Sp1 regulated genes. In vivo studies showed that MTM analogs attained higher exposure at their respective MTD and had lower clearance in mice and primates. Unlike MTM, analogs reversed tumor growth and increased survival at the MTD and 2/3 of MTD.

Conclusion: We demonstrated that MTM analogs are selectively more cytotoxic in tumor cell lines dependent on ETS family TFs and have vastly improved PK properties as confirmed in a primate model. Given their effectiveness at 2/3 of the MTD, they are expected to have an improved therapeutic window.

Citation Format: Markos Leggas, Joseph Eckenrode, Yang Liu, Abhisek Mandal, Reiya Hayden, Oleg Tsodikov, Jon Thorson, Jurgen Rorh. Novel mithramycin analogues with improved pharmacologic profile and efficacy in ETS transcription factor-driven tumors [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A41.

Abstract 2954: Mithramycin analogues disrupt ETS transcription factor DNA binding

Introduction: Ewing sarcoma, prostate cancer, and leukemia are a few examples where ETS transcription factors drive tumorigenesis. The transcription factors EWS-FLI1 and EWS-ERG are common translocations in Ewing sarcoma and bind DNA at GGAA repeats leading to expression of genes that drive tumor growth. Pharmacologic inhibition of EWS-FLI1 with mithramycin (MTM) was shown to inhibit expression of downstream genes and tumor growth in mice. But despite this specific inhibitory activity, MTM has a narrow therapeutic window with hematologic and hepatic toxicity attributed to displacement of the ubiquitously acting Sp1 transcription factor. Thus, a synthetic effort was initiated to develop MTM analogues with reduced toxicity and increased specificity for ETS binding sites. Structural studies informed the design of MTM analogues that may stabilize transcriptional complexes leading to the disruption of transcriptional activity and DNA damage. In vitro cytotoxicity assays demonstrated that MTM analogues have significantly higher cytotoxicity in EWS-ETS expressing cell lines. Here we present mechanistic evidence for the differences in biochemical activity among MTM and its novel analogues.

Methods: Qualitative interactions between drug-DNA-protein were assessed and optimized by electrophoretic mobility shift assays (EMSA). Time-resolved fluorescence energy transfer (TR-FRET) assays were used to quantitatively determine ERG displacement from DNA in the presence of MTM and analogues. Expression of proteins indicating DNA damage (c-PARP, γ-H2AX) and phosphorylation at the C-terminal domain (CTD) of RNAPII was determined by western blot following drug treatments in ETS and non ETS expressing cell lines.

Results: Using TR-FRET, we observed that MTM displaced DNA bound ERG more potently and in a concentration dependent manner as compared to MTM analogues. As compared to MTM, treatment with MTM analogues resulted in higher expression of DNA damage markers, γ-H2AX and c-PARP, specifically in cell lines containing EWS-ETS translocations in a concentration dependent manner.

Conclusion: These studies provide insights regarding differences among MTM and analogues in DNA binding and interactions with DNA associated proteins in the presence and absence of EWS-ETS expression. Our results suggest that MTM analogues may bind and stabilize transcriptional complexes. These differences will provide the basis for structure activity relationships and for the development of analogues with decreased in vivo toxicity. Future work will incorporate co-immunoprecipitation studies to determine if physical protein interactions are being disrupted by MTM and analogues and cellular thermal shift assays to directly probe drug interactions with EWS-ETS proteins and with RNAPII.

Note: This abstract was not presented at the meeting.

Citation Format: Reiya C. Hayden, Caixia Hou, Prithiba Mitra, Abhisek Mandal, Jurgen Rohr, Jon Thorson, Oleg Tsodikov, Markos Leggas. Mithramycin analogues disrupt ETS transcription factor DNA binding [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2954.

Abstract 3630: RNA nanoparticles as a carrier for targeted drug delivery into cancer cells

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the US; the inefficiency of chemotherapeutic treatments has severely limited the treatment options in patients with CRC metastasis. Polyvalent RNA nanoparticles have demonstrated metastatic tumor homing without accumulation in normal organ tissues surrounding metastatic tumors; the flexibility in constructing trimers also enables the assembly of polyvalent nanoparticles to carry drug molecules for therapeutic purposes. The purpose of our study was to: (i) demonstrate PI3K/mTOR inhibitor conjugation to RNA nanoparticles, and (ii) pH-sensitive intracellular drug delivery by folate receptor targeting (FA)-3WJ-PI-103 nanoparticles in CRC cells.

Methods. (1) PI-103-3WJ-Folate nanoparticle binding, internalization and drug release was evaluated in HT-29 (human CRC), SK-OV-3 (human ovarian cancer), JAR (human choriocarcinoma), HCT116 (human CRC), and Caco-2 (human CRC) cell lines. (2) Confocal microscopy was used to examine RNA nanoparticle binding and internalization by endocytosis. (3) Western blot was used to confirm drug delivery with PI-103-3WJ-Folate nanoparticle.

Results. (1) Drug release from fully assembled RNA nanoparticles was confirmed after 3WJ-PI-103 nanoparticles (5 µM) incubation in PBS pH 2.5, 3, 3.5 for 4h at 37°C and analysis of pAkt (Ser473) expression, a marker of PI3K inhibition; 1.5 mM 3WJ-PI-103 was minimum dose required to inhibit PI3K/Akt signaling in cancer cell lines. (2) Rapid folate-receptor mediated RNA nanoparticle internalization was observed within 2-4 h in HT29, HCT116, JAR and SK-OV-3 cell lines by confocal microscopy. (3) Cancer cells were treated with FA-3WJ-PI-103 nanoparticles directly to evaluate all steps of targeted receptor-mediated drug delivery-receptor binding, endocytosis, pH-triggered drug release and endosomal drug escape into the cytoplasm. HCT116 and JAR cells were treated with FA-3WJ-PI-103 in 0% and 1% folate-free media for 4h, media was replaced and evaluated 3h later for PI3K pathway activation. PI3K/Akt signaling was inhibited after direct treatment with FA-3WJ-PI-103 nanoparticles at 5 mM drug concentration; 3WJ-PI-103 particles were used as a control.

Conclusions. A critical finding of our current study was the ability to conjugate PI3K/mTOR inhibitor PI-103, via a pH-selective linker, to RNA nanoparticles and the demonstration of intracellular drug delivery into cancer cells and drug release in a pH-dependent fashion. Our results demonstrate the potential of receptor-selective drug delivery to cancer cells with high FRα expression and represents a promising approach for treatment of CRC metastases.

Citation Format: Piotr G. Rychahou, Sijin Guo, Eun Y. Lee, Nicole Rychagov, Jon Thorson, Peixuan Guo, B. Mark Evers. RNA nanoparticles as a carrier for targeted drug delivery into cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3630.

Abstract B043: Mithramycin-SA analogues with reduced toxicity for the treatment of ETS transcription factor-driven tumors

Introduction: Chromosomal translocations involving the ETS family of transcription factors are common in Ewing sarcoma, prostate cancer, and leukemia. These translocations lead in overexpression of aberrant ETS transcription factors, which drive tumorigenesis. Mithramycin (MTM) inhibits EWS-FLI1, the most common ETS-related transcription factor in Ewing sarcoma, presumably through interference at its DNA binding sites on promoter regions. However, MTM has a narrow therapeutic window marked by severe liver and hematologic toxicities. These are likely the result of interference with the ubiquitously expressed SP1 transcription factor. Here, we sought to develop analogues with specificity toward ETS transcription factors and reduced interaction with SP1. Methods: Using MTM-SA and semisynthetic approaches a series of analogues were obtained. To determine specificity toward cells expressing ETS-related chromosomal translocations, MTM-SA analogues were screened for growth inhibition in a panel of Ewing sarcoma cell lines (n=8), all expressing EWS-ETS translocations, and compared to a panel of non-Ewing cell lines (n=9) that do not express these translocations. Luciferase reporter constructs were developed to evaluate interference with EWS-FLI1 and SP1 regulated genes following MTM-SA analogue treatment. Select analogues were tested in vivo to identify the maximum tolerated dose and determine pharmacokinetics (PK). Results: In growth inhibition assays, several MTM-SA analogues resulted in > 10-fold specificity toward Ewing sarcoma cell lines vs. MTM. Luciferase reporter assays identified two analogues, MTM-SA-Tryptophan-A2 and MTM-SA-Tryptophan-A10, with 10-fold reduced inhibition of SP1 but similar inhibition of EWS-FLI1, as compared to MTM. Additionally, MTM-SA-Phe analogue has lower toxicity, despite longer plasma half-life. Conclusion: These data show that MTM-SA analogues are cytotoxic against tumor cell lines expressing aberrant ETS transcription factors. Further, their reduced interference with the ubiquitously expressed SP1 transcription factor, as well as their improved PK, may result in a wider therapeutic window.

Citation Format: Markos Leggas, Joseph Eckenrode, Prithiba Mitra, Amit Jha, Shaimaa Salem, Abhisek Mandal, Jon Thorson, Jurgen Rohr. Mithramycin-SA analogues with reduced toxicity for the treatment of ETS transcription factor-driven tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B043.

Ensuring the success of women faculty at AMCs: lessons learned from the National Centers of Excellence in Women's Health

Since the early 1970s, the numbers of women entering medical school and, subsequently, academic medicine have increased substantially. However, women faculty have not advanced at the expected rate to senior academic ranks or positions of leadership. In 1996, to counter this trend, the U.S. Department of Health and Human Services (DHHS) Office on Women's Health included women's leadership as a required component of the nationally funded Centers of Excellence in Women's Health to identify effective strategies and initiate model programs to advance women faculty in academic medicine. The authors describe the experience of Centers at seven U.S. medical schools in initiating and sustaining leadership programs for women. The processes used for program formation, the current programmatic content, and program evaluation approaches are explained. Areas of success (e.g., obtaining support from the institution's leaders) and difficulties faced in maintaining an established program (such as institutional fiscal constraints and the diminishing time available to women to participate in mentoring and leadership activities) are reviewed. Strategies to overcome these and other difficulties (e.g., prioritize and tightly focus the program with the help of an advisory group) are proposed. The authors conclude by reviewing issues that programs for women in academic medicine will increasingly need to focus on (e.g., development of new kinds of skills; issues of recruitment and retention of faculty; and increasing faculty diversity).

[Successful prevention of tractor accidents in Sweden]

A decrease in the incidence of tractor roll-over fatalities, from 15/100,000 farm tractors for the period 1957(60 to 0.1/100,000 for the period 1986(90, was associated with a corresponding increase in the proportion of farm tractors equipped with roll-over protection structures (ROPS) from 6 to 93 per cent. Thus, the Swedish approach to the prevention of serious injuries due to tractor roll-over, entailing the compulsory equipment of new tractors with ROPS from July 1st 1959, may be said to have been successful. No other country seems to have introduced such effective safety regulations for the prevention of these injuries.

The 14-3-3 proteins positively regulate rapamycin-sensitive signaling

BACKGROUND

The kinase Tor is the target of the immunosuppressive drug rapamycin and is a member of the phosphatidylinositol kinase (PIK)-related kinase family. It plays an essential role in progression through the G1 phase of the cell cycle. The molecular details of Tor signaling remain obscure, however.

RESULTS

We isolated two Saccharomyces cerevisiae genes, BMH1 and BMH2, as multicopy suppressors of the growth-inhibitory phenotype caused by rapamycin in budding yeast. BMH1 and BMH2 encode homologs of the 14-3-3 signal transduction proteins. Deletion of one or both BMH genes caused hypersensitivity to rapamycin in a manner that was dependent on gene dosage. In addition, alterations in the phosphopeptide-binding pocket of the 14-3-3 proteins had dramatically different effects on their ability to relieve the growth-arresting rapamycin phenotype. Mutations that prevented 14-3-3 from binding to a phosphoserine motif abolished its ability to confer rapamycin resistance. In contrast, substitution of two residues in 14-3-3 that surround these phosphoserine-binding sites conferred a dominant rapamycin-resistant phenotype.

CONCLUSIONS

Our studies reveal 14-3-3 as an important component in rapamycin-sensitive signaling and provide significant new insights into the structure and function of 14-3-3 proteins.

Vehicle-related fatalities among Swedish conscripts

All traffic fatalities among conscripts in Sweden from 1979 through 1988 (N = 106) were studied. More than half (58%) of the victims were on leave, nearly one-third (30%) were traveling to or from the regiment, and 13 (12%) were on duty. Forty-one percent of the drivers on leave who were involved in crashes were inebriated; the mean blood alcohol concentration was 1.6 g/kg. Fifty-two percent of the conscripts on leave were injured in single-vehicle crashes. Fatalities occurring during travel to or from the regiment most often occurred in crashes with another vehicle (69%), and all the drivers were sober. At least one of the fatally injured drivers on duty was inebriated, and in another two crashes, safety belts were not used although this was compulsory for both passengers and drivers. We conclude that collective travel could reduce the danger in traveling to and from the regiment. In addition, identifying alcohol abusers and preventing them from driving is of prime importance. Increased use of safety belts and installation of airbags should also be beneficial as well.

Carbon monoxide suicide from car exhausts

STUDY OBJECTIVE

the aim of the study was to analyse the victims and circumstances in carbon monoxide suicides from car exhausts in order to find strategies for mitigation of the suicide risk.

DESIGN

necropsy, police and hospital records were scrutinized for 194 victims who committed suicide by carbon monoxide poisoning from car exhausts during a four-year period in Sweden.

SETTING AND PARTICIPANTS

the State Institutes of Forensic Medicine in Umeå and Stockholm.

RESULTS

a higher incidence (24.2/million population) was seen in the rural region than in the urban region (14.9). Males dominated (88%), most of them middle aged. Most victims committed suicide in a car outdoors. A vacuum cleaner tube connected to the compartment was most commonly used. Severe disease, mostly psychiatric, was seen in 61% of the victims. Drugs were detected in 8% of the victims under psychiatric treatment. In 37%, earlier suicide behaviour was documented. Suicide notes were found in 40%. Blood alcohol was detected in 51% of the victims and other drugs in 7%.

CONCLUSIONS

environmental changes may reduce the number of carbon monoxide suicide from car exhausts, e.g. introduction of a law requiring catalyst exhaust, of automatic idling stop, and of exhaust pipes incompatible with vacuum cleaner tubes. The importance of accurate treatment of psychiatric patients is stressed.

Nicotinic receptor binding site probed with unnatural amino acid incorporation in intact cells

The nonsense codon suppression method for unnatural amino acid incorporation has been applied to intact cells and combined with electrophysiological analysis to probe structure-function relations in the nicotinic acetylcholine receptor. Functional receptors were expressed in Xenopus oocytes when tyrosine and phenylalanine derivatives were incorporated at positions 93, 190, and 198 in the binding site of the alpha subunit. Subtle changes in the structure of an individual side chain produced readily detectable changes in the function of this large channel protein. At each position, distinct features of side chain structure dominated the dose-response relation, probably by governing the agonist-receptor binding.

National suicide prevention programme and railway suicide

Suicidal behaviour is a public health problem closely related to other problems such as mental illness, abuse, violence and accidents. This approach is illustrated by the prevention of railway suicides. A theoretical framework is sketched, which allows for the use of principles from injury prevention in the prevention of suicide. ICD-9 encoded death certificates from 1974, 1980, 1986 and 1987 which concerned suicides and undetermined deaths on roads and railways were analysed (N = 294). Additional data were collected from autopsy, police and hospital protocols and from interviews with engine-drivers. Railroad victims dominated the sample (78% of cases). The mean age was 42 yr. Alcohol was detected in 27% of cases, drugs in 36% and severe illness (mostly psychiatric) in 57%. The relationship between types of collision and nature of injury is discussed. Environmental changes, such as changing the locomotive front design, are suggested as strategies for reducing accidents and suicides on railways.

Back pain: a study of twins

To evaluate the relationship between genetic factors and back pain, 5029 MZ and 7876 DZ twin pairs were investigated by a questionnaire. The data were analyzed with regard to physical symptoms, eg, back pain, and certain work conditions. Pain was reported by about 17% of the male and 13% of the female twins in the material. The occurrence of back pain was strongly associated with work load, especially among the male twins. Twin concordance regarding back pain was considerably higher in MZ than in DZ twins. Of four groups who were studied, statistically significant differences between the two twin categories were observed in three cases. This result supports the assumption that a relationship exists between genetic factors and the occurrence of back pain. Official registrations for sick-leave pay in a sample of 247 twins confirmed the interview information on back pain. Just a few cases were wrongly classified, ie, they were sick-listed because of back pain but had stated no back pain in the questionnaire.

CD4+ murine T cell clones that express high levels of immunoglobulin binding belong to the interleukin 4-producing T helper cell type 2 subset

A panel of 20 murine CD4+ clones was examined for the presence of surface membrane receptors for IgA, IgM, IgD, IgE, and IgG. High level expression of multiple Fc receptors (FcRs) was found on all Th2 clones. FcR expression was low or undetected on the Th1 clones. The preferential expression of FcR on activated Th2 cells suggests potential mechanisms for immunoregulatory interactions with B cells.

Collisions with passenger cars and moose, Sweden

The number of collisions between motor vehicles and moose is increasing in many countries. Collisions with large, high animals such as moose cause typical rear- and downward deformation of the windshield pillars and front roof, most pronounced for small passenger cars; the injury risk increases with the deformation of the car. A strengthening of the windshield pillars and front roof and the use of antilacerative windshields would reduce the injury risk to car occupants.

Role of cross-bridge distortion in the small-signal mechanical dynamics of insect and rabbit striated muscle

The mechanism of the active tension response of insect fibrillar muscle to step changes and small oscillations of length was re-investigated, following White's demonstration (1983) that the high relaxed stiffness evidently persists during activation and cannot be neglected as had previously been assumed. White's result makes earlier explanations of the small-signal response untenable; the experimental and theoretical studies described here lead to a new class of explanations at the cross-bridge level. The response of an activated muscle to a fast stretch consists of a synchronous tension increase that is followed first by a rapid decay of tension and then by a delayed rise ('stretch activation'). It was shown in glycerinated fibre preparations from the water bug and the bumblebee that subtraction of the relaxed tension response from the active response results in a prominent undershoot of the tension level preceding the step, before the delayed rise of tension. The responses of the same fibres to sinusoidal oscillations, in the frequency range 1-150 Hz, showed an equivalent behaviour, with the active locus circling the relaxed locus in a Nyquist plot, as described by Machin & Pringle (1960). Stiffness was determined during the tension response to a large step (of 1%) by recording the immediate change of tension to a small test step (0.2%), applied at various times after the conditioning step. In the majority of preparations stiffness remained constant or increased during the undershoot of tension. Step and sinusoidal responses with the above features cannot be explained at all by an active component resembling a simple exponential delay. We show, however, that such features are predicted if certain small-signal effects of cross-bridge distortion (previously and erroneously assumed negligible in insect flight muscle for the small-signal case) are incorporated in models of the cross-bridge cycle. Two alternative hypotheses for the effects of distortion are examined: (i) distortion-induced detachments and (ii) distortion-modulated transitions among multiple attached states (Huxley & Simmons, 1971). For the first we also show that the results do not differ qualitatively whether one assumes strain, interfilament displacement or 'bridge recruitment' as the physical correlate of stretch activation. Both of the above explanations account, at least qualitatively, for the observed rapid decay and undershoot of tension following a step increase of length, and for the circling of the active Nyquist-plot loci about the passive locus. The explanation based on distortion-induced detachments, however, appears to be inconsistent with the stiffness measurements.(ABSTRACT TRUNCATED AT 400 WORDS)

An evaluation of the official swedish statistics on seriously injured in road traffic accidents

Only 32 per cent of the category "seriously injured" in road traffic accidents were correctly registered as such in the official road traffic accident statistics. Furthermore, 25 percent were registered, though wrongly, as "slightly injured". Consequently almost one-half of the seriously injured were not registered at all, and they constituted a drop-out which contributes a bias to the statistics obtained. False registration is primarily associated with short-term hospitalization and absence of surgical operations during the hospital stay, i.e. slight injuries, and low age. The material analysed was comprised of 2689 individuals from hospital or road traffic accident statistics covering the Uppsala hospital region during 1966.

Pedal cycle accidents

Injury patterns of people who had sustained pedal cycle accidents were analysed. The main finding was that simple falls among child cyclists are associated with a high risk for trunk injuries caused by impact against handlebar ends. According to animal experiments the preventive principle of spreading the impact is not valid for handlebar trauma or in case of abdominal injuries as a whole.

Industrial accidents in the construction industry

In this investigation, accidents in the Swedish construction industry in 1967 leading to permanent disability or death were studied. The aims were to illustrate the magnitude of the problem and to create a basis of decision for the taking of preventive measures.

The population consisted of nearly 400 cases. The whole population excluding a 5% non-response was studied. The course of events and causes of the accidents were analysed according to the statements of workers, employers and police. The injured workers were interviewed by telephone; otherwise information was acquired from police reports and injury reports of the National Social Insurance Board.

Not only had the injured been subjected to physical suffering and financial problems as a result of the accidents, but the humanitarian losses, in terms of limitations to family life and leisure activities were striking.

Accident prevention must not be restricted to mere technical and psychological measures. According to our results it would be more fruitful to attack juridical, organizational, professional-economical, political circumstances. It is particularly important that a practical plan be formulated and accepted by the responsible authorities.

Distributed relaxation processes in sensory adaptation

Dynamic description of most receptors, even in their near-linear ranges, has not led to understanding of the underlying physical events-in many instances because their curious transfer functions are not found in the usual repertoire of integral-order control-system analysis. We have described some methods, borrowed from other fields, which allow one to map any linear frequency response onto a putative weighting over an ensemble of simpler relaxation processes. One can then ask whether the resultant weighting of such processes suggests a corresponding plausible distribution of values for an appropriate physical variable within the sensory transducer. To illustrate this approach, we have chosen the fractional-order low-frequency response of Limulus lateral-eye photoreceptors. We show first that the current "adapting-bump" hypothesis for the generator potential can be formulated in terms of local first-order relaxation processes in which local light flux, the cross section of rhodopsin for photon capture, and restoration rate of local conductance-changing capability play specific roles. A representative spatial distribution for one of these parameters, which just accounts for the low-frequency response of the receptor, is then derived and its relation to cellular properties and recent experiments is examined. Finally, we show that for such a system, nonintegral-order dynamics are equivalent to nonhyperbolic statics, and that the efficacy distribution derived to account for the small-signal dynamics in fact predicts several decades of near-logarithmic response in the steady state. Encouraged by the result that one plausible proposal can account approximately for both the low-frequency dynamics (the transfer function s(k)) and the range-compressing statics (the Weber-Fechner relationship) measured in this photoreceptor, we have described some formally similar applications of these distributed effects to the vertebrate retina and to analogous properties of mechanoreceptors and chemoreceptors.

Injury diagnoses within morbidity statistics

The present investigation set out to determine the sensitivity of injury classification according to body area and to study the specificity of “commotio cerebri”. It was preceded by several related essays on injury statistics. The sensitivity was at least 0.94 for all body areas except neck and back, for which areas the values were 2/3 (adults) and 4/5 (all age groups). The specificity analysis showed that about half of the “commotio cerebri” diagnoses were not based on incontestable facts; one-seventh of them had no clinical basis at all according to the records.

Sequelae of accidental near-drowning in childhood

Patients admitted to hospital because of near-drownings were followed-up 2–7 years after the admissions. The material comprises 36 children and 15 adults, which is the total number of patients cared for because of accidental near-drownings within the Uppsala Hospital Region 1964–1968. The region contains one-sixth of Sweden's population. Hospital records were examined and parents of the children were interviewed by telephone. Two seriously disabled cases were found. The annual figure for severely and permanently disabled children, injured by near-drownings, is estimated at 2 or 3 for all Sweden. The corresponding point prevalence is estimated to be anything between 50 and 120 patients; this too concerns patients disabled as children. The incidence of children with non-fatal of permanent organic brain injuries due to accidental near-drowning is small compared with the corresponding mortality. Maybe the small probability of being saved within the short time required for this final result is a suitable explanation.

Phosphate starvation and the nonlinear dynamics of insect fibrillar flight muscle

The nonlinear mechanical dynamics of glycerinated insect fibrillar flight muscle are investigated. The most striking nonlinearity reported previously, which often resulted in oscillatory work being limited to frequencies below those of natural flight, disappears if 5 mM or more orthophosphate is added to the experimental solutions. We show that two further asymmetric nonlinearities, which remain even though phosphate is present, are predicted by cross-bridge theory if one takes account of the expected distortion of attached cross-bridges as filament sliding becomes appreciable. Adenosine triphosphate and adenosine diphosphate have opponent effects upon the mechanical rate constants, suggesting a scheme for the sequential ordering of the events comprising the cross-bridge cycle.

Dynamics of excitation and inhibition in the light-adapted Limulus eye in situ

The dynamics of spike discharge in eccentric cell axons from the in situ lateral eye of Limulus, under small sinusoidal modulation of light to which the eye is adapted, are described over two decades of light intensity and nearly three decades of frequency. Steady-state lateral inhibition coefficients, derived from the very low-frequency response, average 0.04 at three interommatidial spacings. The gain vs. frequency of a singly illuminated ommatidium is described closely from 0.004 to 0.4 cps by the linear transfer function s(0.25); this function also accounts approximately for the measured phase leads, the small signal adaptation following small step inputs, and for Pinter's (1966) earlier low-frequency generator potential data. We suggest that such dynamics could arise from a summation in the generator potential of distributed intensity-dependent relaxation processes along the dendrite and rhabdome. Analysis of the dynamic responses of an eccentric cell with and without simultaneously modulated illumination of particular neighbors indicates an effect equivalent to self-inhibition acting via a first-order low-pass filter with time constant 0.42 sec, and steady-state gain near 4.0. The corresponding filters for lateral inhibition required time constants from 0.35 to 1 sec and effective finite delay of 50-90 msec.

Objective measure of the dynamics of a visual movement illusion

Apparent movement in peripheral vision can be induced by sequential flashing of two dots that are spatially unresolved. Subjects used this illusion to make forced-choice estimates of the directional sequence of the two dots. Performance at this task defines spatiotemporal conditions that induce the illusion without reliance upon subjective distinctions of "movement" from "successivity" and "simultaneity." The dynamics of the illusion, defined in this way, are measured and compared with those for after-flash inhibition and the perception of real movement.