[New psychoactive substances in emergency medicine]

New psychoactive substances (NPS) are a heterogeneous group of synthetic intoxicating substances. What they have in common is their "new" appearance as a narcotic drug. Many of them imitate known drugs; some of them are derivatives of substances developed as drugs many years ago. Changed or completely newly developed chemical structures often give the NPS a massively increased effect. This includes not only the effects desired by the consumer, but also the undesirable effects with sometimes fatal consequences. The use of NPS has been an increasing phenomenon for years. In 2018, 2.6% of German adults had already had experience with NPS. NPS-intoxicated persons represent a challenge for the treating physicians not only because of the heterogeneity of the substances, but also because of the unpredictable effects for the users. The clinical assessment is often made more difficult due to the presence of a mixed intoxication. Only systemic toxicological analysis-generally not readily available-provides safety, as conventional rapid or bedside tests do not record many substances. There is no global definition of NPS. A practical, clinical classification differentiates into four groups: synthetic stimulants, synthetic cannabinoids, synthetic hallucinogens, and synthetic sedatives.

EU alerting and reporting systems for potential chemical public health threats and hazards

A number of European and international IT platforms are used to notify competent authorities of new potential chemical exposures. Recently the European Parliament and the Council of European Union adopted new legislation that aims to improve the co-ordinated response to cross border health threats (Decision 1082/2013/EU). The Decision, inter alia, sets provisions on notification, ad hoc monitoring and coordination of public health measures following serious cross border threats to health from biological, chemical and environmental events as well as events that have an unknown origin. The legal instrument applies to all European Union Member States and is comparable to the International Health Regulations in its content, requirements and adoption of a multiple hazards approach. An inter-sectoral and multidisciplinary response to events with potentially dangerous cross border exposure pathways is often required. For example, European Poisons Centres may be aware of cases of toxic exposure to a product and, in parallel, trading standards may be aware of the same product due to a breach of consumer product standards. Whilst both cases would have been recorded for separate purposes in different alerting systems, they relate to the same exposure pathway; therefore a process for linking these records would allow a more robust approach to risk assessment and risk mitigation. The Decision seeks to reconcile this issue for serious threats by linking relevant platforms into one overarching higher level risk management IT platform called the Early Warning Response System (EWRS). This system will serve to link other sectors within the European Commission (EC) to public health (e.g. medicines), as well as other EU agencies and international bodies via co-notification features. Other European alert systems will be linked to EWRS to facilitate information sharing at both the assessment and management levels. This paper provides a timely overview of the main systems run by the EC and other international organisations that provide alerts following chemical incidents that have, or may have, the potential to affect public health. The advantages and further considerations of linking these different systems and sectors are also highlighted. Recommendations are made with the purpose of ensuring that modifications to these systems made to satisfy with EU legislation enable a more timely coordinated response and greater awareness of events in Europe, thereby reducing the public health impact from chemical exposures.

Recovery education: a tool for psychiatric nurses

Patient teaching is vital for nursing care of psychiatric patients. This paper describes the process of developing Recovery Education as a tool for nurses who lead daily patient education groups. Gundersen Lutheran's Recovery Model developed for the Inpatient Psychiatric Unit includes seven Elements of Recovery--Hope, Security, Support/Managing Symptoms, Empowerment, Relationships, Coping and Finding Meaning. Concepts of cognitive behavioural therapy, mindfulness and case-based education were woven through recovery lessons in ready-to-use folders. Statistics on patient satisfaction and patient outcome data were positive. Education for self-management can move patients forward to improve health and healing on their recovery journey.

Countering health threats by chemicals with a potential terrorist background--creating a rapid alert system for Europe

BACKGROUND

The acronym "ASHT" stands for "Alerting System and Development of a Health Surveillance System for the Deliberate Release of Chemicals by Terrorists". Imagine this scenario: 15 patients with respiratory symptoms following a concert in Rome and 12 patients coughing after lunch in a cafeteria in the Czech Republic; are these events related? Today these events would never be connected as there is no mechanism to allow EU Member States to share this type of information effectively. The main objective of the ASHT project was to improve data sharing between EU Member States. In part, this was achieved by an internet accessible EU-wide alerting system with the aim to detect the deliberate (i.e. criminal or terrorist) or accidental release of chemicals. Nevertheless more information from police, fire brigades and health professionals is needed.

METHODS

Description of the design, development, functionality and testing of the relational database system called "RAS-CHEM" (Rapid Alert System for Chemicals).

RESULTS

A database structure appropriate for the description of "events" with sophisticated retrieval functions was developed. For evaluation purposes 37 events were entered into the database including 29 scenarios and 8 historical mass intoxications. The alert level was "background information" for 21 events, "suspected mass intoxication" for 6 cases and "confirmed mass intoxication" for 10 events.

CONCLUSION

The RAS-CHEM database works and will be integrated into the Health Emergency Operations Facility (HEOF) with other European Rapid Alert Systems. Poisons centres receive a large number of enquiries and could be important sentinels in this field of toxicovigilance.

Hernienchirurgie: Wachstumsverhalten humaner Fibroblasten auf alloplastischen Kunststoffnetzen

BACKGROUND

The biocompatibility of meshes in hernia surgery seems to be influenced markedly by the amount of the selected material and its structure. Fibroblasts play a major key role during the process of mesh incorporation. This study was performed to investigate differences in cell morphology and proliferation of human fibroblasts cultured on different polypropylene meshes.

METHODS

In the present in vitro study the cellular response of human fibroblasts was investigated by scanning electron microscopy (SEM), comparing three different polypropylene meshes: a newly constructed low-weight and microporous mesh (NK1), a low-weight and macroporous mesh with absorbable polyglactin filaments (Vypro), and a heavy-weight and microporous mesh (BiomeshP1). Human fibroblasts (1,5.10(5) cells) were incubated with the meshes (each 12 mm(2)) for 6 hours, 5 days, 2, 4, 6, and 12 weeks. Computer-assisted morphometry of the fibroblast/mesh surface ratio served to reflect the biological cell response.

RESULTS

The Vypro mesh showed the significantly highest fibroblast density during the first 6 weeks, but cell growth was nearly exclusively limited to the polyglactin filaments. At 3 months, after reabsorption of the polyglactin, the fibroblast-coated polypropylene mesh surface was only 50% compared to NK1 and BiomeshP1. The morphologic aspect of the fibroblasts on the BiomeshP1 mesh was much more degenerative and unphysiological, compared to NK1 and Vypro, with isolated, single cells instead of a broad, connective growth. The BiomeshP1 showed a significantly higher fibroblast proliferation around the nodes of the mesh compared to the straight filaments. On the NK1 mesh fibroblasts exclusively proliferated on the filaments but not on the pressed mesh surface.

CONCLUSIONS

The polymer surface and structure appears to be of major importance for the biocompatibility of meshes: human fibroblasts preferably grow on low-weight meshes, thin filaments, and mesh nodes. Heavy-weight meshes induce degenerative cell reactions. Polyglactin seems to further improve cell proliferation whereas a pressed mesh surface without pores hinders fibroblast growth.

Prognosis factors in incisional hernia surgery: 25�years of experience

BACKGROUND

Incisional hernia underwent a change from conventional techniques to mesh implantation. The relevance of different factors, like operative technique, mesh material, and patient-related parameters concerning the outcome following mesh repair, are still under debate.

METHODS

In a comparative retrospective study of 421 incisional hernia operations on 348 patients, we investigated 241 Mayo procedures and 180 mesh repairs over a 25-year period. In addition to the quality of life following mesh implantation, the prognostic relevance of demographic, preoperative and intraoperative parameters, surgical technique, mesh material, and the surgeon's experience were analysed, both in a univariate and multivariate manner.

RESULTS

With a mean follow-up of 9.7+/-8.8 years, the total recurrence rate following Mayo overlap was 37%, in contrast to 15% after mesh implantation (P=0.001). Mesh size was the only significant prognostic factor concerning quality of life following mesh implantation, and 86% of the patients with mesh repair were satisfied. The complication rate was determined significantly by patients' risk factors, size of hernia, operative technique, and the surgeon's experience, whereas the rate of recurrences was significantly influenced by the parameters obesity (BMI>25), size of hernia, and surgical experience. The recurrence rate decreased significantly with surgeon's experience-a minimum of 16 mesh repairs led to a recurrence rate of less than 10%.

CONCLUSIONS

Only the mesh repair revealed acceptable recurrence rates with high patient comfort. From a surgical point of view, the most important prognostic factor following mesh repair is the surgeon's experience.

[Cocaine-body-packing. Infrequent indication for laparotomy]

INTRODUCTION

Body-packers or "mules" are drug smugglers who swallow cocaine-filled condoms in order to conceal them during air travel. Body pushers hide drug packages in the rectum or vagina. In a cooperative effort between the Frankfurt Airport Clinic and the GIZ-Nord (Goettingen University poison control center), we performed a retrospective study and developed an algorithm for the problem of "rupture of a cocaine-filled condom in a body-packer."

METHODS

In a retrospective analysis, the data of all cocaine body-packers and body pushers who were identified at Frankfurt International Airport from 1985 to 2001 were evaluated.Temporal development, demographic data, and surgical aspects were of special interest.

RESULTS

From 1985 to 2001 a total of 280 body pushers and 2880 body-packers were identified: 63 "mules" (2.2%) developed symptoms of severe cocaine intoxication following rupture of a condom. Emergency laparotomy was performed on 20 patients (i.e., 32% of all symptomatic body-packers) and the condoms were removed, while 43 body-packers (68%) died before surgical therapy could be initiated. All operated patients survived.

CONCLUSION

Severe cocaine intoxication is life threatening. Patients die from complications caused by generalized vasoconstriction. If the reason for severe cocaine intoxication is the rupture of a cocaine-filled condom,the only possible therapy consists of immediate laparotomy for removal of the condoms.

Myocardial infarction in young adults with low-density lipoprotein cholesterol levels < or = 100 mg/dL: clinical profile and 1-year outcomes

STUDY OBJECTIVES

To define the clinical profile of young adults with optimal low-density lipoprotein (LDL) cholesterol levels who present with acute myocardial infarctions (MIs); to compare and contrast differences in the clinical profiles of young adults admitted to the hospital with MIs who have LDL cholesterol levels < or = 100 mg/dL and those with LDL cholesterol values > or = 160 mg/dL; and to evaluate the clinical outcomes for the two groups at 1 year.

DESIGN

A retrospective chart review was conducted on all young men (55 years) and women (65 years) admitted to the hospital for MIs within a 2-year period (n = 232). A history of cardiovascular risk factors and 1-year outcomes were obtained.

SETTING

Rural community medical center serving a tri-state area in the midwestern United States.

PATIENTS

Patients were included in this analysis if (1) a lipid profile was drawn within 24 h of hospital admission and (2) the patient was not receiving a statin medication on hospital admission.

MEASUREMENTS AND RESULTS

Of the 183 patients who met the inclusion criteria, as many as 68% (124 patients) had LDL cholesterol levels of < or = 130 mg/dL, 29% (53 patients) had LDL cholesterol level of < or = 100 mg/dL, and only 14% (26 patients) had LDL cholesterol levels of > or = 160 mg/dL. Patients were categorized into group 1 if their LDL cholesterol level was < or = 100 mg/dL and were categorized into group 2 if their LDL cholesterol level was > or = 160 mg/dL. In group 2, 92% of patients were placed on a statin medication. By 1 year, the mean LDL cholesterol level had decreased from 188 to 106 mg/dL. The rate of coronary artery bypass graft and percutaneous coronary intervention procedures was similar between groups. Hospital readmission rates (43.4% vs 50%, respectively) and 1-year mortality rates (9% vs 8%, respectively) were not different between groups group 1 and 2.

CONCLUSIONS

Young adults experiencing acute MIs typically have acceptable cholesterol levels (ie, < or = 130 mg/dL) or optimal values (ie, < or = 100 mg/dL). In those patients with abnormal cholesterol levels, a combined strategy of aggressive intervention and adherence to secondary prevention protocols including lipid control is successful in improving outcomes.

Chronic heart failure in the community: missed diagnosis and missed opportunities

BACKGROUND

The aim of this study was to determine the incidence of congestive heart failure (CHF) in patients discharged from a hospital without a diagnosis of CHF who were admitted with shortness of breath and had a low left ventricular ejection fraction (LVEF). CHF is a devastating disease in terms of financial cost, prevalence, and effect on morbidity and mortality. The true incidence rate is not known because of reliance on discharge records and death certificates, and because diagnosis remains a clinical judgment.

METHODS AND RESULTS

CHF was diagnosed by the Framingham criteria. We retrospectively reviewed the records of 225 randomly selected patients admitted with a complaint of shortness of breath and discharged without a diagnosis of CHF (group 1). We compared group 1 with patients admitted at the same time with a diagnosis of CHF and of similar age and LVEF (group 2). In group 1, 100 patients had a low LVEF (< or =40%) and 51% met criteria for CHF that had been missed. Readmission rate was high (42%). Mortality at 12 months was 18%. Rate of cardiomegaly on x-ray films was similar in groups 1 and 2 (64.6% v 64.4%, respectively). Third heart sound (39% v 10%; P <.001) and heart rate > 120 beats/min (41.7% v 12.5%; P <.001) were significantly more frequent in group 1. By contrast, signs and symptoms suggestive of fluid overload were more frequent in group 2.

CONCLUSIONS

Many patients admitted with shortness of breath and low LVEF have CHF but are not diagnosed. Physicians are more likely to miss CHF in patients presenting without signs of fluid overload even when third heart sound is present with resting tachycardia. A missed diagnosis of CHF is associated with a high readmission rate, multiple admissions, and a mortality rate comparable to that of patients with newly diagnosed CHF.

Mild hypercholesterolemia and premature heart disease: do the national criteria underestimate disease risk?

OBJECTIVES

To determine the frequency of hospital admissions for acute coronary syndrome in young adults and to examine the risk factors that predispose to the development of premature heart disease.

BACKGROUND

Significant coronary heart disease (CHD) is considered rare in the young adult. Current guidelines do not recommend treatment of mild cholesterol abnormalities for primary prevention of CHD in the young.

METHODS

This is a large case series of 449 adults (< or =50 years) admitted to the hospital with acute coronary syndrome. A history of cardiovascular risk factors and lipid profile were recorded. The presence and extent of CHD were established.

RESULTS

Mean patient age was 44 +/- 6 years. Documented CHD was present in 61% of hospital admissions. Multivariate analysis revealed that history of hypercholesterolemia, history of smoking and diabetes were independently associated with premature CHD. The fasting lipid profiles were only borderline to mildly abnormal. Serum total cholesterol, low-density lipoprotein (LDL) and triglyceride levels were not different in cases compared with control subjects. Nearly half (49%) of those with LDL levels of > or =160 mg/dl had only one additional risk factor or none. Despite this, a history of hypercholesterolemia had independent and incremental value on other risk factors for the likelihood of premature CHD.

CONCLUSIONS

The magnitude of hospital admissions relating to premature CHD is high. In this population, the presence of borderline or mild hypercholesterolemia has significant effects on the development of premature CHD. These observations have significant implications in the development of guidelines for primary prevention of premature CHD.

Complementary visualization of mitotic barley chromatin by field-emission scanning electron microscopy and scanning force microscopy

The surface structure of mitotic barley chromatin was studied by field-emission scanning electron microscopy (FESEM) and scanning force microscopy (SFM). Different stages of the cell cycle were accessible after a cell suspension was dropped onto a glass surface, chemical fixed, and critically point dried. Imaging was carried out with metal-coated specimen or uncoated specimen (only for SFM). The spatial contour of the chromatin could be resolved by SFM correlating to FESEM data. The experimentally determined volume of the residue chromatin during mitosis was within the range of 65-85 microm(3). A comparison with the theoretically calculated volume indicated a contribution of about 40% of internal cavities. Decondensation of chromosomes by proteinase K led to a drastic decrease in the chromosome volume, and a 3-D netlike architecture of the residue nucleoprotein material, similar to that in the intact chromosome, was obvious. Incubation of metaphase chromosomes in citrate buffer permitted access to different levels of chromatin packing. We imaged intact chromosomes in liquid by SFM without any intermediate drying step. A granular surface was obvious but with an appreciably lower resolution. Under similar imaging conditions proteinase K-treated chromosomes exhibited low topographic contrast but were susceptible to plastic deformations.

Tumor suppressor protein p53 binds preferentially to supercoiled DNA

Wild type human tumor suppressor protein p53 (expressed in insect cells) binds strongly to negatively supercoiled (sc) plasmid DNA at a native superhelix density, as evidenced by electrophoretic retardation of scDNA in agarose gels and imaging by scanning force microscopy (SFM). The binding occurs both in the presence and absence of the p53 consensus sequence. At relatively low p53/DNA ratios, binding of p53 to scDNA results in the appearance of several retarded DNA bands on the gels, similar to a conventional topoisomer ladder generated enzymatically. However, after removal of p53 by deproteination, the original mobility of the scDNA is recovered, indicating that the reduction of torsional stress accompanying p53 binding does not reflect changes in linking number. In DNA samples partially relaxed by topoisomerase I p53 binds preferentially to the scDNA molecules with the largest negative superhelix density. SFM imaging of the p53/scDNA complex reveals a partial or total relaxation of the compact scDNA, the degree of which increases with the number of bound p53 molecules. Competition assays with linear DNA reveal a preference of p53 for scDNA. In addition, scDNA induces dissociation of p53 from a preformed complex with a DNA fragment (474 bp) containing the consensus sequence. We conclude that the affinity of p53 for negatively supercoiled DNA is greater than that for the consensus sequence in linear fragments. However, thermally denatured linearized plasmid DNA is efficient in competing for the binding of p53 to scDNA, although the first retarded band (presumed to contain one bound p53 molecule) is retained in the case of the plasmid containing the consensus sequence. Thus, it appears that interactions involving both the core domain and the C-terminal domain regulate the binding of p53 to scDNA. The above results are not restricted to human p53; the wild type rat p53 protein also results in the retardation of scDNA on agarose gels. The biological implications of the novel DNA binding activities of p53 are discussed.

Striving for atomic resolution in biomolecular topography: the scanning force microscope (SFM)

The invention in 1986 of scanning force microscopy (SFM) provided a new and powerful tool for the investigation of biological structures. SFM yields a three-dimensional view at nanometer resolution of the surface topography associated with biological objects. The potential for imaging either macromolecules or biomolecules and cells under native (physiological) conditions is currently being exploited to obtain functional information at the molecular level. In addition, the forces involved in individual bimolecular interactions are being assessed under static and dynamic conditions. In this report we focus on the imaging capability of the SFM. The rather broad spectrum of applications represented is intended to orient the prospective user of biological SFM.

Sequence-specific labeling of superhelical DNA by triple helix formation and psoralen crosslinking

Site-specific labeling of covalently closed circular DNA was achieved by using triple helix-forming oligonucleotides 10, 11 and 27 nt in length. The sequences consisted exclusively of pyrimidines (C and T) with a reactive psoralen at the 5'-end and a biotin at the 3'-end. The probes were directed to different target sites on the plasmids pUC18 (2686 bp), pUC18/4A (2799 bp) and pUC1 8/4A-H 1 (2530 bp). After triple helix formation at acid pH the oligonucleotides were photocrosslinked to the target DNAs via the psoralen moiety, endowing the covalent adduct with unconditional stability, e.g. under conditions unfavorable for preservation of the triplex, such as neutral pH. Complex formation was monitored after polyacrylamide gel electrophoresis by streptavidin-alkaline phosphatase (SAP)-induced chemiluminescence. The yield of triple helix increased with the molar ratio of oligonucleotide to target and the length of the probe sequence (27mer > 11mer). The covalent adduct DNA were visualized by scanning force microscopy (SFM) using avidin or streptavidin as protein tags for the biotin group on the oligonucleotide probes. We discuss the versatility of triple helix DNA complexes for studying the conformation of superhelical DNA.

Peripheral joint laxity increases in pregnancy but does not correlate with serum relaxin levels

OBJECTIVE

Our purpose was to evaluate peripheral joint laxity during pregnancy and to determine whether serum relaxin levels are associated with increased joint laxity.

STUDY DESIGN

A prospective observational study was performed.

RESULTS

A significant increase in joint laxity was found in five of seven peripheral joints over the course of the pregnancy and post partum. There was no correlation with serum relaxin levels. There were no significant differences in joint laxity on the basis of parity, age, or prepregnancy exercise levels.

CONCLUSIONS

Peripheral joint laxity is noted to increase as pregnancy progresses. The cause of this change is undetermined.

Subclavian hemodialysis catheter infections: a prospective, randomized trial of an attachable silver-impregnated cuff for prevention of catheter-related infections

OBJECTIVE

To determine if an attachable silver-impregnated cuff is effective in reducing subclavian hemodialysis catheter-related infections.

DESIGN

Prospective, randomized, nonblinded study.

SETTING

Community teaching hospital.

PATIENTS

One hundred one acute and chronic renal failure patients requiring subclavian venipuncture and catheterization. After randomization, 47 patients underwent subclavian catheterization with a silver-impregnated cuff (Ag-CC), and 54 patients had routine catheter (RC) placements.

MEASUREMENTS

Multiple presumed predictor variables for catheter-related infections, exit site infection rate, bacteremia rates, and semiquantitative cultures of all catheters.

In vitro formation of "urinary stones": generation of spherulites of calcium phosphate in gel and overgrowth with calcium oxalate using a new flow model of crystallization

Calcium phosphate (CaP) has been detected in the majority of urinary stones containing predominantly calcium oxalate (CaOx). Therefore, crystal phases of CaP might play an important role with respect to the formation of urinary calcium stones in general. Very often, CaP found in stones or tissue of human kidney occurs in the shape of small spherulites. In this paper, we report on a new flow model of crystallization (FMCG), which has been used to generate spherulites of CaP in a gel matrix of 1% agar-agar at 37 degrees C from a supersaturated, metastable solution continuously flowing over the gel surface. Scanning electron microscopy (SEM), X-ray diffraction and microscopic Fourier transformed infrared spectroscopy (FTIR) revealed that the particles formed (diameter: up to 200 microns) consisted of a poorly crystalline core of carbonatoapatite which was partly surrounded by a well-crystallized shell of octacalcium phosphate (OCP) showing radially oriented sheet-like structures. Subsequently, CaOx was grown on these spherulites from a flow of a correspondingly supersaturated solution conducted over the gel matrix. It could be shown by SEM that growth of calcium oxalate monohydrate (COM) was characteristically induced by the OCP shell. Radial sheet-like forms of OCP were directly continued by COM showing a certain radial orientation. The model of crystallization in gel matrices applied here should be well-suited to simulate the process of urinary stone formation under in vitro conditions.

Scanning force microscopy of chromatin fibers in air and in liquid

We have adapted specimen preparation techniques of conventional electron microscopy for visualizing chromatin structures in the scanning force microscope (SFM) in air and in liquid. The beaded substructure of the nucleoprotein filament was obtained after hypotonic lysis of chicken erythrocytes and air drying, whereas supranucleosomal structures were preserved after treatment of cell nuclei with detergent. In the latter case, the nucleosomes were still distinct but appeared more condensed. A modified droplet diffusion-spreading technique of chromatin from Namalwa cells (a human B-lymphoid line) yielded a uniform filamentous morphology and similar fiber appearance. A reversible swelling of spread chromatin was observed upon exposure of air-dried samples to solutions differing in salt concentrations.

Scanning force microscopy of microtubules and polymorphic tubulin assemblies in air and in liquid

We have investigated microtubules (MTs) and polymorphic assemblies, formed in vitro from isolated microtubule protein, by scanning force microscopy (SFM) in air and in liquid. Immobilization of MTs was achieved by placing a drop of the assembly solution on a polylysine-coated coverslip. After washing with taxol and air drying, the characteristic microtubular fibrous morphology appeared in the SFM. The MTs formed a network similar to that obtained by transmission electron microscopy (TEM). A height of approximately 9.5 nm for dried MTs was computed from the surface topography. Glutaraldehyde fixation of the MTs yielded higher structures (approximately 14 nm), which swelled to approximately 20 nm after rehydration, a value close to the MT diameter of approximately 25 nm determined from TEM images of ultrathin sections. The protofilament pattern of the MTs and surface attached MT-associated proteins were not apparent from SFM, although the height along the long axis of the MTs appeared slightly modulated. In addition to MTs, various polymorphic tubulin assemblies including ribbons, hoops and double-walled MTs were visualized by SFM.

Structural hierarchy in the clustering of HLA class I molecules in the plasma membrane of human lymphoblastoid cells

Major histocompatibility complex (MHC) class I antigens in the plasma membranes of human T (HUT-102B2) and B (JY) lymphoma cells were probed by immunochemical reagents using fluorescence, transmission electron, and scanning force microscopies. Fluorescent labels were attached to monoclonal antibodies W6/32 or KE-2 directed against the heavy chain of HLA class I (A, B, C) and L368 or HB28 against the beta 2-microglobulin light chain. The topological distribution in the nanometer range was studied by photobleaching fluorescence resonance energy transfer (pbFRET) on single cells. A nonrandom codistribution pattern of MHC class I molecules was observed over distances of 2-10 nm. A second, nonrandom, and larger-scale topological organization of the MHC class I antigens was detected by indirect immunogold labeling and imaging by transmission electron microscopy (TEM) and scanning force microscopy (SFM). Although some differences in antigen distribution between the B- and T-cell lines were detected by pbFRET, both cell lines exhibited similar clustering patterns by TEM and SFM. Such defined molecular distributions on the surfaces of cells of the immune system may reflect an underlying specialization of membrane lipid domains and fulfill important functional roles in cell-cell contacts and signal transduction.

The scanning force microscopy of DNA in air and in n-propanol using new spreading agents

We present recent advances in DNA specimen preparation technique for scanning force microscopy (SFM) based on spreading on mica in the presence of cationic and non-ionic detergents. Reproducible DNA imaging in air and in n-propanol has been achieved in the presence of the non-ionic detergent 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30) or the cationic detergent cetylpyridinium chloride (CP) in a microdrop containing nanograms of DNA. In an alternative procedure, a microdrop of detergent is applied to the surface just prior to the DNA. Quantitative image analysis yields as the apparent molecular dimensions of the DNA a width of approximately 7 nm and a height of approximately 0.7 nm, and delineates the problems of DNA metrology by SFM.

Imaging subcellular structures of rat mammary carcinoma cells by scanning force microscopy

Scanning force microscopy (SFM) was used for imaging subcellular structures of cultured rat mammary carcinoma cells dried in air. Identification of cellular substructures was achieved by immunofluorescence and specific fluorescence probes. Cells grown attached to a glass support exhibited submicrometer thickness in the dried state. Inside the nuclear domain the nucleoli appeared as prominent conical protrusions. Membrane extensions, microspikes and microvilli were well preserved at the cell periphery after fixation in glutaraldehyde vapor and air-drying and were distinguishable either as isolated elements or intercellular communications. The plasma membrane and soluble proteins were selectively removed with nonionic detergent in a buffer system. The mitochondria were concentrated primarily in the perinuclear space and exhibited a well defined filamentous shape. Their identity was confirmed by specific fluorescence staining with rhodamine 123. In the membrane-free system achieved by dry-cleaving of the sample surface, the cytoskeletal network was resolved as a complex mesh of actin-containing fiber bundles interwoven with a filigree arrangement of thinner filaments. The smallest fibrous substructures revealed by SFM with the scanning tips used to date were approximately 8 to 10 nm in height and 80 nm in width.

Probing specific molecular conformations with the scanning force microscope. Complexes of plasmid DNA and anti-Z-DNA antibodies

An anti-Z-DNA IgG antibody was used to probe for the left-handed Z-DNA conformation of a d(CG)11 insert in a negatively supercoiled plasmid DNA (pAN022). The complexes were spread on mica in the presence of a quaternary ammonium detergent benzyldimethylalkylammonium chloride and imaged with a scanning force microscope (SFM). The high affinity anti-Z-DNA antibody was retained even after restriction endonuclease cleavage of the DNA. The two arms in the product molecules had unequal lengths in conformity with the known location of the Z-DNA forming insert. Most complexes exhibited one IgG per DNA molecule. The bound antibodies were up to approximately 35 nm in diameter and extended approximately 2 nm from the mica surface. They were generally in a lateral orientation relative to the DNA, in accordance with prior chemical modification experimental data indicating a bipedal mode of binding for an anti-Z-DNA IgG. However, the SFM images also suggest that the DNA bends to accommodate the two Fab combining regions of the antibody. This study demonstrates the utility of the SFM for investigating conformation-dependent molecular recognition.

Probing chromatin with the scanning force microscope

With the scanning force microscope (SFM), one can image the topography of biological material adsorbed at air-solid or liquid-solid interfaces with up to nanometer resolution. In principle, fixation, contrast enhancement, and labeling are not required. We have adapted specimen preparation techniques of conventional electron microscopy for visualizing chromatin ultrastructures in the SFM. A beaded substructure of the nucleoprotein filament was obtained after hypotonic lysis of chicken erythrocytes and air drying. The beads-on-a-string morphology of the basic nucleosomal assembly was well delineated. The nucleosomes appeared as round protrusions with an apparent height of 4-6 nm. The histogram of center-to-center distances between adjacent nucleosome cores along the filament axis had a peak at approximately 30 nm. Reversible changes in the three-dimensional structure were observed upon exposure of air-dried samples of metaphase chromosomes to solutions of different ionic strengths.

Dysfunctional labor after external cephalic version

OBJECTIVE

To determine whether there is a greater occurrence of dysfunctional labor or a higher incidence of cesarean delivery for failure to progress in women who have undergone a successful version for breech presentation.

METHODS

Using a retrospective case-control design, 76 women who had undergone a successful version from January 1988 through July 1993 were identified and their medical records reviewed. The control population was matched for delivery date, parity, and gestational age.

RESULTS

There was no difference in the cesarean delivery rates for failure to progress between women undergoing successful version (6%) and the control population (6%). The incidence of dysfunctional labor between the groups did not differ significantly. Dysfunctional labor requiring oxytocin augmentation occurred in 29.6% of women who had undergone a version and in 24.2% of the control population (P = .6530).

CONCLUSION

There is no significant increase in the cesarean delivery rate in women undergoing a version for breech presentation.

Scanning force microscopy of circular and linear plasmid DNA spread on mica with a quaternary ammonium salt

Scanning force microscopy (SFM) offers the potential for subnanometer resolution in the investigation of nucleic acids, proteins, and their complexes. SFM is not bound by the requirement of classical transmission electron microscopy (TEM) for contrast enhancement through shadow casting or negative staining. A primary challenge, however, has been the reproducible fixation of samples on an atomically flat surface such as mica. We have developed a method for the routine imaging by SFM of supercoiled, relaxed, and linearized plasmid DNA, immobilized on freshly cleaved mica through the spreading action of benzyldimethylalkylammonium chloride (BAC) at micromolar concentrations. A reproducibly high yield of well-spread, dispersed molecules is obtained and background contamination is minimal. The contour lengths of the relaxed and linearized molecules imaged in air agree well with the helical rise (3.4 A/bp) of B-DNA in solution. We have also introduced the use of quantitative image analysis of SFM images to determine apparent molecular width and height over the entire molecular path.

Structure and dynamics of the complex of single stranded DNA binding protein of Escherichia coli with circular single stranded DNA of filamentous phages

We have analyzed the equilibrium and nonequilibrium properties of the complex of the single stranded DNA binding protein of Escherichia coli (EcoSSB) and circular single stranded DNA of filamentous phages M13mp8 and F1 using static and dynamic light scattering, analytical ultracentrifugation and electron microscopy. Upon binding to the single stranded DNA the EcoSSB tetramer replaces an equivalent volume of water trapped within the coiled single stranded DNA and hinders the folding of the single stranded DNA into secondary structures at all salt concentrations. The salt dependent compaction of the stoichiometric complex can be described assuming a flexible polyelectrolyte chain. The solution structure of the macromolecular complex is a random coil and in the electron microscope a beaded flexible structure of the complex with a bead diameter of 6 nm appears at all salt concentrations used. The internal motions of the stoichiometric complex can be described by the Rouse-Zimm model of polymer dynamics. The segmental mobility of the complex can be correlated with changes in the binding site size of the EcoSSB tetramer; it indicates the presence of interactions between EcoSSB tetramers bound to single stranded DNA.

Salt dependent changes in structure and dynamics of circular single stranded DNA of filamentous phages of Escherichia coli

We have analyzed the static and dynamic behaviour of the circular single stranded DNA of the filamentous Escherichia coli phages F1 and M13mp8 in solution as a function of salt concentration using static and dynamic light scattering and sedimentation analysis in the analytical ultracentrifuge. We show by static light scattering that native and denatured single stranded DNA behave like a randomly coiled macromolecule at all salt concentrations used. The size of the native single stranded DNA is governed by the formation of secondary structures. While the radius of gyration decreases with increasing salt concentration the translational diffusion of the center-of-mass of native single stranded DNA and the sedimentation coefficient increase with increasing salt concentration in a biphasic manner. Below 100 mM monovalent cation concentration there is a strong dependence of the hydrodynamic parameters upon salt which is reduced approx. 3-fold at higher salt concentrations. We attribute the compaction of single stranded DNA by salt to electrostatic shielding and, in case of native single stranded DNA, secondary structure formation. Internal motions of the native single stranded DNA are observable at all salt concentrations and can be interpreted with a model of segmental diffusion of the elements of the polymer chain. The observed segmental diffusion coefficient of the native single stranded polynucleotide increases with increasing salt under the conditions investigated.

Kinetics of binding of single-stranded DNA binding protein from Escherichia coli to single-stranded nuclei acids

The time course of the reaction of Escherichia coli single-stranded DNA binding protein (E. coli SSB) with poly(dT) and M13mp8 single-stranded DNA has been measured by fluorescence stopped-flow experiments. For poly(dT), the fluorescence traces follow simple bimolecular behavior up to 80% saturation of the polymer with E. coli SSB. A mechanistic explanation of this binding behavior can be given as follows: (1) E. coli SSB is able to translocate very rapidly on the polymer, forming cooperative clusters. (2) In the rate-limiting step of the association reaction, E. coli SSB is bound to the polymer only by one or two of its four contact sites. As compared to poly(dT), association to single-stranded M13mp8 phage DNA is slower by at least 2 orders of magnitude. We attribute this finding to the presence of secondary structure elements (double-stranded structures) in the natural single-stranded DNA. These structures cannot be broken by E. coli SSB in a fast reaction. In order to fulfill its physiological function in reasonable time, E. coli SSB must bind newly formed single-stranded DNA immediately. The protein can, however, bind to such pieces of the newly formed single-stranded DNA which are too short to cover all four binding sites of the E. coli SSB tetramer.

Acute renal failure in octogenarians

We analyzed hospital survival rates, severity of illness, and long-term outcomes in patients from three different age groups who were treated with hemodialysis for acute renal failure (ARF). Patients over age 80 had fewer bad prognostic factors. This selection bias was reflected in their hospital survival rates of 53%, compared to 57% of patients under age 70. No selection bias for patients ages 70 to 79 years was identified, and their hospital survival rate was 27%. The long-term outcome of hospital survivors was poor, particularly in the very elderly. Physicians should consider all of these factors when deciding whether to offer hemodialysis to elderly patients suffering from ARF.

Sterilization of contrast media (Isovist) containing liposomes by ethylene oxide

Liposomes containing Isovist were prepared by controlled detergent dialysis as well as by reverse phase evaporation. After preparation these liposomes were lyophilized and then submitted to sterilization by ethylene oxide. Prior to lyophilization, trehalose was added as a protective agent to preserve the size of the liposomes. After each step in the preparation size distribution was determined by photon correlation spectroscopy. The computer program CONTIN was adapted for the data analysis and proved to be applicable for polydisperse solutions of liposomes. Neither freeze-drying nor sterilization had negative effects on the morphological quality of the samples when using 4 g of trehalose per 1 g of lipid. In addition, the quality of the liposomes was controlled by scanning electron microscopy. At the end of seven days, no growth of microorganisms occurred in any of the samples.