Non-invasive and invasive autonomic tests to facilitate cardioneuroablation and complex indications for transcutaneous lead extraction and discontinuation of permanent pacing

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

Rare-A-Care registry

Background

 Extracardiac vagal nerve stimulation (ECANS) and cardioneuroablation (CNA) are promising methods to cure vagally mediated bradycardia and validate indications for permanent pacing for sinus node dysfunction (SND), atrioventricular blocks (AVB), tachycardia-bradycardia syndrome (TBS) and cardio-inhibitory or mixed reflex syncope (VVS). There are limited information on clinical utility of those procedures in validation of indication for continuation of permanent pacing (PM) and transcutaneous lead extraction (TLE).

Methods

 Data were collected from prospective multicentre registry of CNA facilitated by interdisciplinary consultations, state-of-art autonomic tests, atropine/propranolol tests, electrophysiologic study as well as ECANS. Share-decision making were used by EP-HEART-TEAM to developed patient-oriented therapy.

Results

 Between June 2018-Jan 2021 the first 102 consecutive patients underwent interdisciplinary approach before invasive EPS and/or invasive ECANS, to consider biatrial, binodal CNA, if possible to cure functional bradycardia. Eleven (10%) patients had implanted permanent PM"s due to SND/AVB/TBS/CI-VVS and were considered for TLE. In 2 out of 11 cases CNA was not performed due to: 1) structural advanced 2nd and 3rd degree AVB with indication for TLE and permanent HBP (no.1), 2) incidental severely symptomatic persistent 3rd degree AVB more than 15 year ago without any further bradycardia episodes (only TLE, no.2). In further 9 of 11 cases with PM CNA was performed, however TLE was not attempted in 2 patients [(SND + PVC ablation + indication for beta-blocker therapy due to IHD in older male. TLE had not yet been attempted to confirm long-term success therapy by patient and/or physician (no.3); two periprocedural successful CNA resulted in disappearance of CI reflex however  despite pacing syncopal events persist due to mixed etiology (no.4)]. In further 7/11 cases TLE-s were performed. Three cases had TLE prior to CNA [VVS-CI + advanced functional AVB - prior 3 pacemaker reimplantations and further "rescue" CNA, (no.5); CI-VVS + pacemaker infection (no.6); TLE of PM + TBS no.7]. Finally, in 4 cases TLE was recommended after CNA [CI-VVS (no.8, no.9 and no.10); mixed etiology: TBS + VVS-CI + intermittent, recurrent pericardial efffusion due to lead perforation, PM syndrome, (no. 11)]. 

Conclusions

 Interdisciplinary and comprehensive autonomic approach with ECANS and CNA enable EP-HEART-TEAM to offer patient-oriented therapy with a complex clinical scenarios before final decision about TLE and discontinuation of permanent pacing therapy.

Socioeconomic inequalities in duration of untreated psychosis: evidence from administrative data in England

BACKGROUND

Duration of untreated psychosis (DUP) is an important measure of access to care as it predicts prognosis and treatment outcomes. Little is known about potential socioeconomic inequalities in DUP. The aim of this study was to investigate inequalities in DUP associated with socioeconomic deprivation in a national cohort in England.

METHOD

We analysed a cohort of 887 patients with a first-episode in psychosis using the administrative Mental Health Services Dataset in England for 2012/13-2014/15. We used a Generalised Linear Model to account for non-linearity in DUP and looked at inequalities across the whole distribution of DUP using quantile regression.

RESULTS

The median DUP was 22 days (mean = 74 days) with considerable variations between and within the 31 hospital providers. We found evidence of significant inequalities regarding the level of socioeconomic deprivation. Patients living in the second, third and fourth deprived neighbourhood quintiles faced a 36, 24 and 31 day longer DUP than patients from the least deprived neighbourhoods. Inequalities were more prevalent in higher quantiles of the DUP distribution. Unemployment prolonged DUP by 40 days. Having been in contact with mental health care services prior to the psychosis start significantly reduced the DUP by up to 53 days.

CONCLUSIONS

Socioeconomic deprivation is an important factor in explaining inequalities in DUP. Policies to improve equitable access to care should particularly focus on preventing very long delays in treatment and target unemployed patients as well as people that have not been in contact with any mental health professional in the past.

Bid-induced release of AIF from mitochondria causes immediate neuronal cell death

Mitochondrial dysfunction and release of pro-apoptotic factors such as cytochrome c or apoptosis-inducing factor (AIF) from mitochondria are key features of neuronal cell death. The precise mechanisms of how these proteins are released from mitochondria and their particular role in neuronal cell death signaling are however largely unknown. Here, we demonstrate by fluorescence video microscopy that 8-10 h after induction of glutamate toxicity, AIF rapidly translocates from mitochondria to the nucleus and induces nuclear fragmentation and cell death within only a few minutes. This markedly fast translocation of AIF to the nucleus is preceded by increasing translocation of the pro-apoptotic bcl-2 family member Bid (BH3-interacting domain death agonist) to mitochondria, perinuclear accumulation of Bid-loaded mitochondria, and loss of mitochondrial membrane integrity. A small molecule Bid inhibitor preserved mitochondrial membrane potential, prevented nuclear translocation of AIF, and abrogated glutamate-induced neuronal cell death, as shown by experiments using Bid small interfering RNA (siRNA). Cell death induced by truncated Bid was inhibited by AIF siRNA, indicating that caspase-independent AIF signaling is the main pathway through which Bid mediates cell death. This was further supported by experiments showing that although caspase-3 was activated, specific caspase-3 inhibition did not protect neuronal cells against glutamate toxicity. In conclusion, Bid-mediated mitochondrial release of AIF followed by rapid nuclear translocation is a major mechanism of glutamate-induced neuronal death.

Congenital amegakaryocytic thrombocytopenia--report of a new c-mpl gene missense mutation

A 44-month old girl with congenital amegakaryocytic thrombocytopenia, already with pancytopenia, underwent an unrelated allogeneic cord blood transplantation with recovery of normal blood cell counts. The patient was a compound heterozygote for two c-mpl missense mutations inherited from both parents, one of them, a G578A exon 4 mutation leading to a cysteine to tyrosine replacement of codon 193, previously unreported.

Lice, nits, and school policy

BACKGROUND

The epidemiology of head lice infestation is poorly understood. Many schools treat all children with nits as though they are contagious. Children with nits but no lice are often removed from school until they are treated and all visible nits are removed.

OBJECTIVE

To investigate the probability that children with nits alone will become infested with lice.

DESIGNS

Prospective cohort study.

SETTING

Two metropolitan Atlanta elementary schools.

PARTICIPANTS

A total of 1729 children were screened for head lice. Twenty-eight children (1.6%) had lice, whereas 63 (3.6%) had nits without lice. Fifty of the 63 children (79%) with nits alone completed follow-up.

OUTCOME MEASURE

Conversion (ie, becoming infested with lice) within 14 days after initial screening.

RESULTS

Nine of 50 children (18.0%) followed for nits alone converted. Although children who converted did not have significantly more nits than did nonconverters, having nits near the scalp was a risk factor for conversion. Seven of 22 children (31.8%) with >/=5 nits within one fourth inch of the scalp converted, compared with 2 of 28 children (7.1%) with fewer (relative risk: 4.45; 95% confidence interval: 1.03-19.35). This risk remained statistically significant after separately stratifying for sex, recent treatment, and total number of nits.

CONCLUSIONS

Although having >/=5 nits within one fourth inch of the scalp was a risk factor for conversion, most children with nits alone did not become infested. Policies requiring exclusion from school and treatment for all children with nits alone are likely excessive. Instead, these children may benefit from repeated examination to exclude the presence of crawling lice.lice, pediculus, lice infestations, pediatrics, school.

The Bcr N-terminal oligomerization domain contributes to the full oncogenicity of P190 Bcr/Abl in transgenic mice

The Bcr/Abl P190 oncoprotein is responsible for the development of Philadelphia-chromosome positive acute lymphoblastic leukemia (ALL). The Bcr moiety in Bcr/Abl activates the Abl tyrosine kinase, an ingredient essential for the transforming capability of Bcr/Abl. Residues 1-63 of Bcr form an N-terminal oligomerization domain and are key to Abl activation in vitro. Mice transgenic for P190 BCR/ABL reproducibly develop an aggressive B-lineage lymphoblastic leukemia/lymphoma. Here we test the hypothesis that residues 1-63 of Bcr have a major in vivo contribution to the oncogenicity of Bcr/Abl P190 by the generation of mice transgenic for an N-terminal deleted form of P190. We find that although the transgene is expressed in the bone marrow of mice at an early age, the incidence of leukemogenesis is greatly diminished as compared to mice transgenic for non-mutated P190 Bcr/Abl. Sporadic hematological malignancies which did develop showed decreased levels of phosphotyrosine as compared to those of wild-type P190 transgenics, although Ras was activated. These results demonstrate that the Bcr oligomerization domain contributes to the oncogenicity of Bcr/Abl in vivo.

Treatment of Bcr/Abl-positive acute lymphoblastic leukemia in P190 transgenic mice with the farnesyl transferase inhibitor SCH66336

The Philadelphia (Ph) chromosome is found in approximately 3% of pediatric patients with acute lymphoblastic leukemia (ALL) and the percentage markedly increases in adult patients. The prognosis for this class of patients is poor, and no standard chemotherapy combination so far has demonstrated long-term efficacy. The Ph-translocation joins the BCR and ABL genes and leads to expression of a chimeric Bcr/Abl protein with enhanced tyrosine kinase activity. This increase in activity leads to malignant transformation by interference with basic cellular functions such as the control of proliferation, adherence to stroma and extracellular matrix, and apoptosis. One important pathway activated by Bcr/Abl is the Ras pathway. Ras proteins have to undergo a series of posttranslational modifications to become biologically active. The first modification is the farnesylation of the C-terminus catalyzed by farnesyl transferase. We studied the effect of the farnesyl transferase inhibitor SCH66336 in an in vivo murine model of Bcr/Abl-positive acute lymphoblastic leukemia. In the early leukemic phase, mice were randomly assigned to a treatment, a vehicle, and a nontreatment group. The treatment was well tolerated without any detectable side effects. All animals of the control groups died of leukemia/lymphoma within 103 days (range, 18-103 days). In contrast, 80% of the drug-receiving group survived without any signs of leukemia or lymphoma until termination of treatment, after a median treatment period of 200 days (range, 179-232 days). We conclude that farnesyl transferase inhibitor SCH66336 is able to revert early signs of leukemia and significantly prolongs survival in a murine ALL model.

Crkl enhances leukemogenesis in BCR/ABL P190 transgenic mice

The adapter protein Crkl has been implicated in the abnormal signal transduction pathways activated by the Bcr/Abl oncoprotein, which causes Philadelphia-positive leukemias in humans. To investigate the role of Crkl in tumorigenesis, we have generated transgenic mice that express human Crkl from the CRKL promoter. Western blot analysis showed a 4-6-fold overexpression of transgenic Crkl above endogenous crkl in two lines and increased constitutive complex formation between Crkl and C3G, an exchange factor for the small GTPase Rap1. This was associated with a significant increase in integrin-based motility of transgenic macrophages. Overexpression of Crkl was associated with increased incidence of tumor formation, and Rap1 was activated in a metastatic mammary carcinoma. The coexpression of Crkl and Bcr/Abl in mice transgenic for P190 BCR/ABL and CRKL markedly increased the rapidity of development of leukemia/lymphoma, decreasing the average survival by 3.8 months. These results provide direct evidence that Crkl plays a role in tumor development and is important in the leukemogenesis caused by Bcr/Abl.

Reduced oncogenicity of p190 Bcr/Abl F-actin-binding domain mutants

The deregulated Bcr/Abl tyrosine kinase is responsible for the development of Philadelphia (Ph)-positive leukemia in humans. To investigate the significance of the C-terminal Abl actin-binding domain within Bcr/Abl p190 in the development of leukemia/lymphoma in vivo, mutant p190 DNA constructs were used to generate transgenic mice. Eight founder and progeny mice of 5 different lines were monitored for leukemogenesis. Latency was markedly increased and occurrence decreased in the p190 del C lines as compared with nonmutated p190 BCR/ABL transgenics. Western blot analysis of involved hematologic tissues of the p190 del C transgenics with end-stage disease showed high-level expression of the transgene and tyrosine phosphorylation of Cbl and Hef1/Cas, proteins previously shown to be affected by Bcr/Abl. These results show that the actin-binding domain of Abl enhances leukemia development but does not appear to be an absolute requirement for leukemogenesis.

Double induction strategy including high dose cytarabine in combination with all-trans retinoic acid: effects in patients with newly diagnosed acute promyelocytic leukemia. German AML Cooperative Group

A prospective multicenter study was performed to investigate the clinical and molecular results of intensified double induction therapy including high-dose cytarabine (ara-C) in combination with ATRA in newly diagnosed acute promyelocytic leukemia (APL), followed by consolidation and 3 years maintenance therapy. Fifty-one patients, diagnosed and monitored from December 1994 to June 1999, were evaluated. The median age was 43 (16-60) years. The morphologic diagnosis was M3 in 40 (78%) and M3v in 11 (22%) patients. In 15 (30%) patients the initial white blood cell counts were > or =5 x 10(9)/l. The cytogenetic or molecular proof of the translocation t(15;17) was a mandatory prerequisite for eligibility. The diagnosis was confirmed by karyotyping in 46 and by RT-PCR of the PML/RARalpha transcript in 45 cases. The rate of complete hematological remission was 92% and the early death rate 8%. Monitoring of minimal residual disease by RT-PCR of PML/RARalpha (sensitivity 10(-4)) showed negativity in 29 of 32 (91%) evaluable cases after induction, in 23 of 25 (92%) after consolidation, and in 27 of 30 (90%) during maintenance, after a median time of 2, 4 and of 18 months after diagnosis, respectively. After a median follow-up of 27 months, the estimated actuarial 2 years overall and event-free survival were both 88% (79, 97), and the 2 years relapse-free survival 96% (90, 100). The high antileukemic efficacy of this treatment strategy is demonstrated by a rapid and extensive reduction of the malignant clone and by a low relapse rate. The results suggest that the intensity of the induction chemotherapy combined with ATRA is one of the factors which may have a critical influence on the outcome of APL. A randomized trial should assess the value of an induction therapy including ATRA and high-dose ara-C in comparison to standard-dose ara-C.

HERV-IP-T47D, a novel type C-related human endogenous retroviral sequence derived from T47D particles

A new type C retrovirus-related endogenous pol sequence (ERV-FTD) found to be occasionally copackaged in retrovirus-like particles released by the human mammary carcinoma cell line T47D was used to screen a human genomic library (Seifarth W, Skladny H, Krieg-Schneider F, Reichert A, Hehlmann R, and Leib-Mösch C: J Virol 1995;69:6408-6416). The DNA sequence of one full-length clone now reveals a human endogenous proviral sequence (HERV) of 4190 bp in length comprising a 5' LTR (489 bp) and regions with 37 and 74% overall amino acid homology to RTVL-Ia gag and pol genes, respectively. About 35 related elements were found to be distributed on all human chromosomes except 16, 17, and Y. Sequence comparisons with Mo-MuLV and various type C-related HERVs suggest that despite a proline primer-binding site this novel HERV element, now named HERV-IP-T47D, can be assigned to one family together with known HERV-I elements. Phylogenetic analyses of 5 proviral and 25 solitary LTR sequences confirmed the existence of two distinct but closely related subgroups of the HERV-IP superfamily in the primate genome. In contrast to most known HERV-families, the evolutionary age of HERV-IP elements dates back prior to the divergence of New and Old World monkeys. Despite their old age, members of the HERV-IP family are still transcriptionally active and were found to be highly expressed in specific human tissues such as liver and kidney.

Molecular heterogeneity in complete cytogenetic responders after interferon-alpha therapy for chronic myelogenous leukemia: low levels of minimal residual disease are associated with continuing remission. German CML Study Group and the UK MRC CML Study Group

A substantial minority of patients with chronic myelogenous leukemia (CML) achieve a complete response (CR) to treatment with interferon-alpha (IFN), defined as the disappearance of Philadelphia chromosome-positive metaphases. Currently it is unclear how long IFN treatment should be continued for such patients. We used a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) to quantify levels of BCR-ABL transcripts in 297 peripheral blood specimens collected from 54 patients who had achieved CR with IFN. The median duration of observation was 1.9 years (range, 0.3-11.0 years). Total ABL transcripts were quantified as internal control and results were expressed as the ratio BCR-ABL/ABL. All 54 patients had molecular evidence of residual disease, although 3 patients were intermittently PCR negative. The median BCR-ABL/ABL ratio at the time of maximal response for each patient was 0.045% (range, 0%-3. 6%). During the period of observation 14 patients relapsed, 11 cytogenetically to chronic phase disease and 3 directly to blastic phase. The median ratio of BCR-ABL/ABL at maximal response was significantly higher in patients who relapsed than in those who remained in CR (0.49% versus 0.021%, P < 0.0001). Our findings show that the level of residual disease falls with time in complete responders to IFN, but molecular evidence of disease is rarely if ever eliminated. The actual level of minimal residual disease correlates with the probability of relapse. We suggest that for patients who reach CR, IFN should be continued at least until relatively low levels of residual leukemia are achieved. (Blood. 2000;95:62-66)

Processing and editing of overlapping tRNAs in human mitochondria

Overlapping tRNA genes in mitochondria of many metazoans introduce a problem for the processing of such polycistronic primary transcripts. Using runoff transcripts and an S100 extract from HeLa cell mitochondria, the processing of the human mitochondrial tRNATyr/tRNACys precursor (carrying an overlap of one base) was investigated: tRNACys is released in its complete form carrying the overlapping residue at the first position, whereas tRNATyr lacks that nucleotide at the discriminator position. Partial deletion of tRNACys or complete replacement by a non-tRNA-like sequence does not alter the processing reaction and indicates that the upstream tRNATyr alone is recognized by a 3'-endonuclease activity. The truncated 3'-end of this tRNATyr is then completed in an editing reaction that incorporates the missing residue. The processing of this tRNA overlap seems to be species-specific, because an overlapping tRNA precursor (tRNASer(AGY)/tRNALeu(CUN)) from opossum mitochondria is not recognized by the human extract. Because processing activities for overlapping and nonoverlapping tRNA precursors could not be separated, it seems that one general activity is responsible for the 3'-end processing of mitochondrial tRNAs and that this activity coevolved with the particular overlap between tRNATyr and tRNACys in human mitochondria, being unable to recognize overlaps between other tRNAs.

Cyclin A1 is predominantly expressed in hematological malignancies with myeloid differentiation

Cyclin A is a cell cycle regulatory protein that functions in mitotic and S phase control in mammalian cells. However, in contrast to other G1 phase regulatory proteins, such as cyclin D, retinoblastoma protein and p16INK4A, cyclin A seems not to be commonly involved in tumorigenesis. Recently, a second human cyclin A--cyclin A1--has been identified. In contrast to cyclin A which is expressed throughout embryonic development and in adult tissue, the expression of cyclin A1 has been reported to be restricted to embryonic and germ line cells. We have confirmed the absence of cyclin A1 mRNA from normal peripheral blood leukocytes of seven healthy donors by single step reverse transcriptase-polymerase chain reaction (RT-PCR). Furthermore, we have examined the expression of cyclin A1 mRNA in 173 peripheral blood samples of 162 patients with various hematological malignancies. Cyclin A1 mRNA was detectable in 11 of 11 patients with acute myeloid leukemia, three of three patients with acute biphenotypic leukemia, eight of eight patients with myelodysplastic syndrome, 59 of 69 patients with chronic myelogenous leukemia (CML) at diagnosis, 13 of 15 patients with CML in blastic transformation, 10 of 18 patients with chronic lymphocytic leukemia, two of nine patients with essential thrombocythemia, and only two of 10 patients with acute lymphoblastic leukemia (ALL) with both cyclin A1 RT-PCR positive ALL leukemias being undifferentiated relapses. In addition, cyclin A1 mRNA was found in one of six leukapheresis products, harvested from individuals without hematological disorders. Taken together, cyclin A1 is expressed in the majority of myeloid and undifferentiated hematological malignancies as well as in normal hematopoietic progenitor cells. We conclude that cyclin A1, a protein potentially involved in G1/S phase progression of immature cells, might be necessary for proliferation of early hematopoietic progenitor cells and their leukemic counterparts being blocked at that stage of differentiation.

Molecular monitoring of residual disease in chronic myelogenous leukemia patients after therapy

The degree of tumor load reduction after therapy, which is determined by the degrees of cytoreduction and cytogenetic response, is an important prognostic factor for patients with chronic myelogenous leukemia (CML). Conventional metaphase analysis is considered to be the "gold standard" for evaluating cytogenetic response. The frequency of cytogenetic analysis can be reduced considerably if patients are monitored by molecular methods, such as quantitative Southern blot, fluorescence in situ hybridization (FISH), quantitative western blot, or competitive reverse transcriptase polymerase chain reaction (RT-PCR). Molecular methods can be performed on peripheral blood specimens and are therefore less invasive than cytogenetic analyses of bone marrow metaphases. Furthermore these techniques are applicable to Ph-negative/BCR-AbL-positive cases. Results obtained by Southern blotting, western blotting, and FISH are readily quantifiable but their sensitivity is not generally superior to that of cytogenetic methods. RT-PCR is by far the most sensitive method. Quantitative RT-PCR analysis is the method of choice for monitoring patients after bone marrow transplantation (BMT). Using competitive PCR in patients after BMT, reappearance and/or rising levels of BCR-ABL transcripts can be detected prior to relapse. All complete cytogenetic responders to interferon-alpha are positive for BCR-ABL transcripts. The level of residual disease spans a range over found orders of magnitude. In both interferon-alpha-treated patients and patients after BMT a good correlation between BCR-ABL transcript numbers per microgram of RNA and cytogenetic results has been found. Variables in the competitive PCR assay may be controlled for by quantification of transcripts of the normal ABL gene as an internal standard. We suggest a stepwise strategy for diagnosis and follow-up of CML patients employing molecular methods.

The Intracellular pH of Clostridium paradoxum, an Anaerobic, Alkaliphilic, and Thermophilic Bacterium

When the extracellular pH was increased from 7.6 to 9.8, Clostridium paradoxum, a novel alkalithermophile, increased its pH gradient across the cell membrane ((Delta)pH, pH(infin) - pH(infout)) by as much as 1.3 U. At higher pH values (>10.0), the (Delta)pH and membrane potential ((Delta)(psi)) eventually declined, and the intracellular pH increased significantly. Growth ceased when the extracellular pH was greater than 10.2 and the intracellular pH increased to above 9.8. The membrane potential increased to 110 (plusmn) 8.6 mV at pH 9.1, but the total proton motive force ((Delta)p) declined from about 65 mV at pH 7.6 to 25 mV at pH 9.8. Between the extracellular pH of 8.0 and 10.3, the intracellular ATP concentration was around 1 mM and decreased at lower and higher pH values concomitantly with a decrease in growth rate.

Thermobrachium celere gen. nov., sp. nov., a rapidly growing thermophilic, alkalitolerant, and proteolytic obligate anaerobe

More than 40 isolates of a novel, ubiquitous, proteolytic, moderately alkaliphilic, thermophilic obligate anaerobe were obtained from geothermally and anthropogenically heated environments and mesobiotic environments located on three continents. Whole-cell protein sodium dodecyl sulfate gel electrophoresis revealed that most of these organisms are very similar. Eight of the isolates were characterized in detail; this analysis included 16S ribosomal DNA sequence analysis. The cells of those organisms are (depending on the isolate) 0.5 to 0.8 micron in diameter and 1.5 to 13 microns long, exhibit tumbling motility, and have a positive Gram stain reaction. The temperature range for growth is 43 degrees to 75 degrees C (optimum temperature, 66 degrees C), and the pH range for growth is 5.4 to 9.5 (optimum pH, 8.2); the shortest doubling time is around 10 min. Yeast extract is required for growth, and (depending on the strain) glucose, sucrose, fructose, galactose, and ribose are utilized. The fermentation products from glucose in the presence of yeast extract are CO2, H2, acetate, formate, and ethanol. The G + C content is 30 to 31 mol%. On the basis of these properties, which differentiate these strains from all alkalitolerant thermophiles described previously, and the results of a comparison of the 16S ribosomal DNA sequences of these organisms with previously described sequences, we propose that our isolates be placed in a single species of the new genus Thermobrachium; strain JW/YL-NZ35 is the type strain of the the type species, Thermobrachium celere.

Membrane microstructural templates for enzyme domain formation

Soluble proteins can spontaneously self-organize into two-dimensional domains at membrane interfaces, given sufficient mobility and specificity to membrane-localized ligands. The authors' recent results studying interfacial domain formation of the membrane-active enzyme, phospholipase A2, indicate that lateral phase separation of heterogeneous membrane mixtures creates anionic templates of specific morphology onto which the enzyme deposits, forming large protein assemblies. Selective removal of membrane components (lysolipid or fatty acid) produces different enzyme interfacial responses and domain morphologies. This leads to the conclusion that complex chemical and physical interactions laterally in the lipid membrane interface as well as between bound protein molecules play a role in organizing protein structures.

Parents' self-reported behaviors related to health and safety of very young children

This survey documented self-reported health and safety behaviors of parents of children enrolled in Head Start programs. The sample consisted of eight preschool programs (n = 1143) from different geographical areas of the country. This survey obtained baseline data on parent self-reported behavior as it relates to priority issues in child health and safety. A 25-item questionnaire assessed parents' behavior related to injury prevention, fire and electrical safety, firearm storage, poison prevention, automobile safety, and child supervision. More than 90% of parents reported they use car seats, teach handwashing and pedestrian safety, and keep medicine and alcohol out of children's reach. Fewer than 60%, however, reported they keep guns and bullets stored separately and locked, possess a working fire extinguisher, or have the poison control telephone number available. Findings provide direction for emphasis for those developing or implementing a comprehensive family health education program.

The ternary complex of DNase I, actin and thymosin beta4

We have recently described a method for identifying contact sites between actin and thymosin beta4 (Tbeta4) by following spectrophotometrically the extent and kinetics of distinct, thiol-specific crosslinking reactions between appropriate derivatives of the two proteins [Reichert et a]. (1996) J. Biol. Chem. 271, 1301-1308]. In the present study this method was used to show that such crosslinking, which is indicative of complex formation, occurs to the same extent with the actin-DNase I complex as with pure actin, although at a somewhat lower rate. Further evidence for the formation of the ternary complex was given by gel electrophoresis. From fluorescence spectroscopy the KD value of Tbeta4 from the actin-DNase I complex was found to be identical to that from pure actin. In line with these data, the capacity of actin for inhibiting DNase I was not affected by the addition of Tbeta4. In conclusion, DNase I and Tbeta4 are independent of each other in their interaction with actin, suggesting that the binding sites of thymosin beta4 and DNase I on actin do not overlap. A ternary complex of DNase I, actin and Tbeta4, if obtained in crystalline form, could thus provide an approach for studying the interface of Tbeta4 and actin by X-ray analysis.

A 'litmus test' for molecular recognition using artificial membranes

BACKGROUND

Sensitive and selective molecular recognition is important throughout biology. Certain organisms and toxins use specific binding at the cell surface as a first step towards invasion. A new series of biomolecular materials, with novel optical and interfacial properties, have been designed to sense molecular recognition events. These polymers, the diacetylenic lipids, have previously been shown to undergo chromatic transitions in response to virus binding to the surface of the material.

RESULTS

Gangliosides that specifically bind cholera toxin, heat-labile Escherichia coli enterotoxin and botulinum neurotoxin were incorporated into a matrix of diacetylenic lipids, 5-10% of which were derivatized with sialic acid. The lipids were self-assembled into Langmuir-Blodgett layers and polymerized with ultraviolet irradiation, yielding a polydiacetylene membrane with a characteristic blue color into which the ganglioside is non-covalently incorporated. When toxin is added, the polymerized membrane turns red. The response is specific and selective, and can be quantified by visible absorption spectrophotometry.

CONCLUSIONS

Polydiacetylenic lipid membranes offer a general 'litmus test' for molecular recognition at the surface of a membrane. A concentration of 20 ppm of protein could be detected using polymerized thin films. The speed, sensitivity and simplicity of the design offers a new and general approach towards the direct colorimetric detection of a variety of different molecules.

Identification of contact sites in the actin-thymosin beta 4 complex by distance-dependent thiol cross-linking

Binding sites of actin and thymosin beta 4 were investigated using a set of bifunctional thiol-specific reagents, which allowed the insertion of cross-linkers of defined lengths between cysteine residues of the complexed proteins. After the cross-linkers were attached to actin specifically at either Cys10, Cys374, or the sulfur atom of the ATP analog adenosine 5'-O-(thiotriphosphate) (ATP gamma S), the actin derivatives were reacted with synthetic thymosin beta 4 analogs containing a cysteine at one of the positions 6, 17, 28, 34, and 40. Immediate cross-linking as followed by UV spectroscopy was found for Cys374 of actin and Cys6 of thymosin beta 4, indicating that the N terminus of thymosin beta 4 is in close proximity (< or = 9.2 A) to the C terminus of actin. In contrast, only insignificant reactivity was measured for all thymosin beta 4 analogs when the cross-linkers were anchored at Cys10 of actin. A second contact site was identified by cross-linking of Cys17 and Cys28 in thymosin beta 4 with the ATP gamma S derivative bound to actin, indicating that the hexamotif of thymosin beta 4 (positions 17-22) is in close proximity (< or = 9.2 A) to the nucleotide. The importance of the amino acids 17 and 28 in thymosin beta 4 for the interaction with actin was emphasized by the finding that thymosin analogs containing cysteine in these positions exhibited strongly reduced abilities to inhibit actin polymerization.

Retrovirus-like particles released from the human breast cancer cell line T47-D display type B- and C-related endogenous retroviral sequences

The human mammary carcinoma cell line T47-D releases retrovirus-like particles of type B morphology in a steroid-dependent manner (I. Keydar, T. Ohno, R. Nayak, R. Sweet, F. Simoni, F. Weiss, S. Karby, R. Mesa-Tejada, and S. Spiegelman, Proc. Natl. Acad. Sci. USA 81:4188-4192, 1984). Furthermore, reverse transcriptase (RT) activity is found to be associated with particle preparations. Using a set of degenerate primers derived from a conserved region of retroviral pol genes, we repeatedly amplified three different retroviral sequences (MLN, FRD, and FTD) from purified T47-D particles in several RT-PCR experiments. Screening of a human genomic library and Southern blot analysis revealed that these sequences are of endogenous origin. ERV-MLN represents a multicopy family of human endogenous retroviral elements (HERVs) with two closely related copies and up to 20 more distantly related members. In contrast, ERV-FRD and ERV-FTD comprise only one copy and five to seven related elements per haploid human genome. DNA sequence analysis of the proviral pol region of ERV-MLN revealed an uninterrupted stretch of 241 amino acids that shows 65% identity with the RT of the type B-related HERV designated HERV-K10. ERV-FRD and ERV-FTD are defective type C-related HERVs. The pol gene of ERV-FRD displays a nucleotide homology of 54% to the gibbon ape leukemia virus, and the pol gene of ERV-FTD is about 67% homologous to members of the RTVL-I family of HERVs. Our results thus indicate that the retroviral particles released by the breast cancer cell line T47-D are probably generated by complementation of several endogenous proviruses and can package retroviral transcripts of different origins.

Total Alignment of Calcite at Acidic Polydiacetylene Films: Cooperativity at the Organic-Inorganic Interface

Biological matrices can direct the absolute alignment of inorganic crystals such as calcite. Cooperative effects at an organic-inorganic interface resulted in similar co-alignment of calcite at polymeric Langmuir-Schaefer films of 10,12-pentacosadiynoic acid (p-PDA). The films nucleated calcite at the (012) face, and the crystals were co-aligned with respect to the polymer's conjugated backbone. At the same time, the p-PDA alkyl side chains reorganized to optimize the stereochemical fit to the calcite structure, as visualized by changes in the optical spectrum of the polymer. These results indicate the kinds of interactions that may occur in biological systems where large arrays of crystals are co-aligned.

The sulfoxide of thymosin beta 4 almost lacks the polymerization-inhibiting capacity for actin

Thymosin beta 4 (T beta 4), a peptide of 43 amino acids, binds to actin monomers and inhibits filament formation. In preparations of T beta 4 from bovine lung tissue, the peptide is accompanied by a derivative in which the methionine residue in position 6 is replaced by its sulfoxide. T beta 4 sulfoxide inhibits actin polymerization to an extent approximately 20-times less than T beta 4. While an equimolar amount of T beta 4 prevented actin polymerization almost completely, polymerization with the corresponding amount of the sulfoxide proceeded in a manner similar to that of pure actin, except for a slight retardation. We showed that the decrease in the inhibitory activity is reflected by a 20-times lower affinity to actin. Interestingly, under non-polymerizing conditions, the affinity of T beta 4 sulfoxide for actin is as high as that of T beta 4 (approximately 1 microM). In accordance with this, no differences were found between T beta 4 and the sulfoxide in cross-linking experiments with the monomer, where both forms of the peptide yielded similar amounts of a 47-kDa band representing conjugates of actin and beta-thymosin, as proved by Western-blotting analysis. Likewise, both, T beta 4 and the sulfoxide retarded the exchange of G-actin-bound nucleotide to similar extents. Although the sulfoxide is presumably a product of autoxidation, it is attractive to speculate that oxidation of the methionine residue in T beta 4 may represent a regulatory switch for starting filament formation in non-muscle cells.

Polymerization of actin from the thymosin beta 4 complex initiated by the addition of actin nuclei, nuclei stabilizing agents or myosin S1

Thymosin beta 4 forms a 1:1 complex with actin and thereby prevents polymerization. Rapid formation of filaments from this complex was observed, however, when actin trimers were added. Polymerization can likewise be initiated by the addition of one equivalent of phalloidin or, less effectively, cytochalasin B. Since both toxins, which reportedly support nucleation, have similar effects as the covalently linked actin trimers, it appears that the formation of filaments from the actin-thymosin beta 4 complex depends on the availability of stable actin nuclei. Remarkably, rapid polymerization was also observed if small amounts of myosin S1 were added, suggesting that also myosin, a protein functionally connected with polymeric actin, can serve as a nucleation center. Considering the existence of thymosin beta 4 and related peptides in numerous mammalian tissues, our data suggest that spontaneous formation of microfilaments in non-muscle cells may be regulated at the level of nucleation. Uncontrolled polymerization induced by the formation of phalloidin-stabilized nuclei may explain the acute toxic effects of phalloidin in hepatocytes.

[Early changes in the hip joint following epiphysiolysis of the femoral head. Results of an MRT study]

With the aim of detecting patients at risk of developing coxarthritis, 34 patients were investigated prospectively by MRI 6-14 years after epiphysiolysis for slipped capital femoral head. In particular, cartilage changes were analysed by gradient-echo sequences. In 40% of the hip joints investigated cartilaginous lesions were present, detectable as irregularity and flattening of contour and more rarely as changes in signal intensity. In contrast, only 18% of the radiographs available revealed any pathology. When pelvic X-rays are normal or reveal slight sclerosis, cartilaginous lesions on MRI are considered early signs of coxarthrosis. This combination was seen especially often in patients with a primarily high angle of dislocation and in those who needed treatment by reposition or osteotomy. Only in 8 of the 17 hip joints showing sclerosis on conventional radiograms, sclerosis was also diagnosed by MRI, possibly because of partial volume and susceptibility effects at high field strength. Even with limited spatial resolution, cartilage examination is warranted in young patients in whom early osteoarthritis can be expected.

Use of bimanyl actin derivative (TMB-actin) for studying complexation of beta-thymosins. Inhibition of actin polymerization by thymosin beta 9

By reacting trimethylammoniobromobimane bromide (TMB bromide) with rabbit muscle actin, a fluorescent reporter group was linked to cysteine at position 374. Fluorescence of TMB-actin decreased significantly on addition of thymosin beta 4 (T beta 4), a peptide of 43 amino acid residues reported to bind to monomeric actin and to prevent filament formation. Based on this effect, we determined the KD value of the thymosin beta 4 complex as 0.8 microM, a value that is in agreement with previous determinations. In addition to the main compound thymosin beta 4, bovine tissue contains a related peptide, thymosin beta 9 (T beta 9), which has 41 amino acid residues and ca. 75% sequence homology. In the present study we show for the first time that T beta 9, similar to T beta 4, forms a 1:1 complex with monomeric actin, and hereby inhibits actin polymerization. With a KD value of 1.1 microM the affinity of T beta 9 is in the same range as that of T beta 4, suggesting that T beta 9, like T beta 4, contributes to maintaining the pool of monomeric actin in bovine non-muscle cells. Further proof of the interaction of T beta 9 with actin was provided by native PAGE, where the complex showed the reported higher mobility, as well as by crosslinking experiments. Using different crosslinking reagents, like water-soluble carbodiimide (EDC), m-maleimidobenzoyl-N-hydroxysuccinimidate (MBS), and disuccinimidylsuberate (DSS), we were able to produce conjugates of 47 kDa. In one of these (from MBS) both actin and T beta 9 could be identified by immunoblotting. When, in the MBS crosslinking experiments, native actin was replaced with (374-NEM)-actin, the 47 kDa band was not seen, indicating that Cys-374 takes part in the thiol-specific crosslinking reaction. This suggests that part of the binding site of T beta 9 must be located close to the carboxy-terminus.

Transplacental induction of pancreas tumors in hamsters by ethanol and the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

Epidemiological studies suggest that smoking during pregnancy and passive exposure of children to cigarette smoke may increase the cancer risk in children and young adults. We have previously shown that the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is an active transplacental carcinogen in Syrian golden hamsters when administered by s.c. injections to pregnant females. The majority of tumors in the offspring developed in the respiratory tract. Since in smoking women the respiratory tract is the portal of entry of tobacco-related carcinogens, including NNK, we have investigated the transplacental effects of NNK given by intratracheal instillation to pregnant hamsters. The modulating effect of ethanol on the transplacental carcinogenicity of NNK in this system was also investigated because smoking and consumption of alcoholic beverages are observed in pregnant women. Our data show that exposure to NNK via the maternal respiratory tract causes a similar tumor incidence in the offspring as the s.c. route of administration. Ethanol greatly enhanced the carcinogenic response to NNK, and up to 60% of the offspring exposed in utero to ethanol and NNK developed tumors of the exocrine pancreas.

The stability and functional properties of proteoliposomes mixed with dextran derivatives bearing hydrophobic anchor groups

Liposomes composed of Escherichia coli phospholipid were coated with polysaccharides bearing hydrophobic palmitoyl anchors. The effect on the stability of liposomes without or with integral membrane proteins was investigated. A high concentration of hydrophobized dextrans protected the liposomes against detergent degradation, decreased the fluidity of the membranes, prevented fusion of the liposomes and enhanced their stability. Proteoliposomes containing beef heart cytochrome-c oxidase and the lactose transport carrier of E. coli were similarly affected by coating with the dextrans. Under these conditions both membrane proteins were still active. Long-term stability of the coated liposomes was obtained only in the absence of the integral membrane proteins.

Spontaneous domain formation of phospholipase A2 at interfaces: fluorescence microscopy of the interaction of phospholipase A2 with mixed monolayers of lecithin, lysolecithin and fatty acid

Fluorescence microscopy has recently been proven to be an ideal tool to investigate the specific interaction of phospholipase A2 with oriented substrate monolayers. Using a dual labeling technique, it could be shown that phospholipase A2 can specifically attack and hydrolyze solid analogous L-alpha-DPPC domains. After a critical extent of monolayer hydrolysis the enzyme itself starts to aggregate forming regular shaped protein domains (Grainger et al. (1990) Biochim. Biophys. Acta 1023, 365-379). In order to confirm that the existence of hydrolysis products in the monolayer is necessary for the observed aggregation of phospholipase A2, mixed monolayers of D- and L-alpha-DPPC, L-alpha-lysoPPC and palmitic acid in different ratios were examined. The phase behavior and the interaction of these films with phospholipase A2 were directly visualized with an epifluorescence microscope. Above a certain critical concentration of lysolecithin and palmitic acid in the monolayer, compression of these mixed films leads to phase separation and formation of mixed domains of unknown composition. Their high negative charge density is evidenced by preferential binding of a cationic dye to these phase-separated areas. Introduction of fluorescence-labeled phospholipase A2 underneath these mixed domains results in rapid binding of the protein to the domains without visible hydrolytic activity, regardless of whether the L-form or the D-form of the DPPC were used. In binary mixtures, only those with DPPC/palmitic acid show formation of phase-separated areas which can be specifically targeted by phospholipase A2 leading to a rapid formation (within 2 min) of protein domains. Experiments with pyrenedecanoic acid containing monolayers give the first direct evidence that acid is located above the enzyme domains. These results show that a locally high negative charge density of the phase-separated domains is one of the prerequisites for the binding of phospholipase A2. In addition, however, small amounts of D- or L-alpha-DPPC headgroups within the domains of the monolayer seem to be necessary for recognition followed by fast binding of the protein to the domains. This is confirmed by experiments with mixed monolayers of diacetylene carboxylic acid and D-alpha-DPPC. The acid--immiscible with lecithin--forms well defined pure acid domains in the monolayer. While the cationic dye can be docked rapidly to these phase separated areas, no preferential enzyme binding and thus no protein domain formation below these acid domains can be induced.

Small unilamellar liposomes from mixed natural and polymeric phospholipids: stability and susceptibility to phospholipase A2

The concept of the uncorkable liposome composed of phase-separated mixtures of a polymerized phospholipid and an enzymically digestible phospholipid has been investigated, using small unilamellar vesicles composed of mixtures of (polymerized) dienoylphosphatidylcholine (DENPC) and dimyristoylphosphatidylcholine (DMPC). Mixed liposomes, even those containing only 10% DENPC, were much more stable than DMPC liposomes, as indicated by the release of entrapped [3H]inulin or [14C]glucose. DMPC liposomes released entrapped solute on exposure to phospholipase A2, whereas mixed vesicles were resistant. The results are compared with those of an earlier study on monolayers of similar compositions. It is concluded that the liposomes, like the monolayers, are phase-mixed, and that uncorkable liposomes cannot be constructed from the phospholipid mixture employed. It is proposed that, until further experimental evidence is produced, the enzymatically uncorkable liposome must be regarded as a theoretical construct.