Dynamic blood cell contact with biomaterials: validation of a flow chamber system according to international standards

The increasing number of patients requiring prosthetic substitution of segments of the vascular system strongly supports the need to optimize a relevant, standardized testing panel for new materials designed for synthetic vascular prostheses. The ISO gives the standard requirements for testing biomaterials provided for implantation. Our primary interest was the establishment of a reliable in vitro panel as a useful and relevant screening system for vascular implant devices to evaluate blood/device interactions under flow conditions. The aim of the present study was to evaluate influences of different flow conditions on blood cell-biomaterial interactions with special emphasis on the interactions of human granulocytes (PMN) and polymeric surfaces. PMN were isolated and vital cells were quantified by flow cytometrical analysis directly before, as well as immediately after the experiments. The viscosity of the final cellular suspension was analysed by using a computerized cone-plate rheometer. As reference materials we used FEP-teflon, PVC-DEHD, PU, PP and PE. Dacron and ePTFE synthetic vascular protheses were tested in a comparative way to those references. The adhesion processes were observed over a period of 40 minutes under arterial (shear stress 0.74 Pa) and venous (shear stress 0.16 Pa) flow conditions in a parallel plate flow chamber system under highly standardized conditions and laminar flow. The cells were observed with the help of inverse light microscopy. Cell behaviour was recorded and analysed in both analogue (video) and digital (imaging system) modes. Samples of the cell suspensions were obtained at regular time intervals and analysed by enzyme linked immuno sorbent assay (ELISA) to quantify LTB4 release. Irrespective of the material, approximately 3 to 4 times more PMN adhered to the biomaterial surfaces under venous flow conditions compared to the arterial. Shear intensity did not influence the running order of biomaterials with respect to cell numbers. This response in descending order at the end of the experiments was as follows: PU, PVC-DEHD, PP, PE and ePTFE. The biochemical analyses indicate that in the system used only a weak effect on LTB4 release induced by the different materials could be determined. A significant effect caused by flow conditions was not observed. Further experiments, both static as well as dynamic, must be performed for multiple, relevant parameters of haemocompatibility, for potential biomaterials as well as those currently in use in vascular prostheses.

Proximal myotonic myopathy with MRI white matter abnormalities of the brain

Proximal myotonic myopathy (PROMM) is an autosomal dominantly inherited multisystemic disorder characterized by myotonia, proximal muscle weakness, and cataracts. This disorder is not linked to the gene locus of myotonic dystrophy (DM). We describe three new families with PROMM. In all patients, CTG repeats of the DM gene in DNA from blood leukocytes were normal. MRI of the brain revealed a consistent pattern of marked white matter hyperintensity on T2-weighted images in four patients; two additional patients had similar but mild to moderate MRI abnormalities. The morphology of these abnormalities is unknown. Clinical symptoms of brain disease were not consistent and included mental changes with hypersomnia, parkinsonian features, stroke-like episodes, and seizures. The causative relationship of these clinical features with the MRI white matter abnormalities remains to be established. Our observations suggest that PROMM may involve the brain.

Stability of bilayer lipid membranes on different metallic supports

In order to arrive at an optimized s-BLM protocol, the influence of various metallic supports (silver, iridium and stainless steel) of different diameters (from 0.14 to 0.33 mm) on the process of forming and stability of supported phospholipid bilayer membranes was studied. In addition, experiments were made using different membrane-forming solutions, ionic strength and pH. The transmembrane resistance and the current ratio between bare and lipid-coated wire at +670 mV were measured. Teflon-coated stainless steel support (0.33 mm in diameter) covered with 2% crude ox brain fraction of phospholipids was most convenient for the formation of supported bilayer lipid membranes on solid support. The well-known stabilizing effect of cholesterol was confirmed for the s-BLM system. Both the pH in the range 5.0-8.0 (silver and stainless steel supports) and the ionic strength (for all types of supports) in the range from 0.025 to 0.1 mol/l at pH 7.0 were found not to be crucial.

European Gene Mapping Project (EUROGEM): breakpoint panels for human chromosomes based on the CEPH reference families. Centre d'Etude du Polymorphisme Humain

Meiotic breakpoint panels for human chromosomes 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 17, 18, 20 and X were constructed from genotypes from the CEPH reference families. Each recombinant chromosome included has a breakpoint well-supported with reference to defined quantitative criteria. The panels were constructed at both a low-resolution, useful for a first-pass localization, and high-resolution, for a more precise placement. The availability of such panels will reduce the number of genotyping experiments necessary to order new polymorphisms with respect to existing genetic markers. This paper shows only a representative sample of the breakpoints detected. The complete data are available on the World Wide Web (URL http:/(/)www.icnet.uk/axp/hgr/eurogem++ +/HTML/data.html) or by anonymous ftp (ftp.gene.ucl.ac.uk in/pub/eurogem/maps/breakpoints).

[Using a computer for accessing information in environmental medicine]

Decisions or statements about the health effects of "pollutants" are often based on not exactly known exposure conditions and/or doubtful cause-effect relationships. Even searches in international databases will not always give adequate answers or produce new problems for the specialist in environmental medicine because the information may be contradictory or leave a wide scope for interpretation, perhaps requiring detailed specialized knowledge (e.g. mutagenicity testing, immunotoxicological parameters etc.). In situations like these, inter-disciplinary working is the mandatory condition. Therefore electronic communication systems might be used to resolve problems, because they provide access to well-presented knowledge of competent colleagues. However, the fundamental concept of such mailbox system for environmental medicine requires active participation by all its users who should contribute to its files and not remain passive, i.e. only call for information.

Germline mosaicism in 4q35 facioscapulohumeral muscular dystrophy (FSHD1A) occurring predominantly in oogenesis

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominantly inherited neuromuscular disorder affecting facial and shoulder girdle muscles with subsequent progression to the pelvic girdle and lower extremities. The major gene involved has been localized to chromosome 4q35 (FSHD1A). The 4q35 DNA marker p13E-11 (D4F104S1) detects a de novo EcoRI DNA rearrangement of < 30 kb in isolated and familial cases. The intrafamilial size of the fragment is constant, inversely correlated with the severity, and directly correlated with the age of onset of the condition. There has been evidence of parental mosaicism in FSHD1A for the D4F104S1 locus. Four female and three male clinically unaffected parents have been described to be carriers of EcoRI fragments of the same size as their affected offspring, but with a markedly less intensive hybridization signal (semi-quantitative evidence). In our total sample of 42 FSHD1A families, we found semi-quantitative evidence of parental D4F104S1 mosaicism in 11 families (EcoRI fragment size range: 12-27 kb). On analysis with adjacent 4q35 probes (D4S163, D4S139), additional qualitative evidence of germline mosaicism could be obtained in two families. In our mosaic families and in the families reported in the literature, a female predominance of mosaicism carriers (13 females versus 5 males) could be noted. In our sample, mosaicism was observed in multigeneration families, in families with isolated cases, and in families with two and three affected children from seemingly unaffected parents. A short EcoRI fragment once having emerged in a mosaicism carrier was found to be transmitted autosomal dominantly to subsequent generations. Of all reported sporadic patients, 19% have a mosaic parent. Finding evidence of parental mosaicism in all our families with more than one affected child of seemingly unaffected parents suggests that there is no autosomal recessively inherited form of FSHD1A.

Diagnosis of Creutzfeldt-Jakob disease by two-dimensional gel electrophoresis of cerebrospinal fluid

BACKGROUND

The diagnosis of Creutzfeldt-Jakob disease (CJD) is based on clinical and electroencephalographic criteria which do not allow a reliable diagnosis to be made during life.

METHODS

Serum and cerebrospinal fluid (CSF) samples were obtained after informed consent from relatives of suspected cases of CJD referred to the German CJD surveillance unit. CSF samples from 58 definite (neuropathologically verified), 46 probable, and 34 possible CJD cases, and from 44 patients without CJD were analysed by two-dimensional gel electrophoresis (2-DE). Two investigators blinded to clinical findings recorded the presence of two proteins, p130/131. The kappa value for the level of agreement between these investigators was calculated. Results obtained were compared with the determination of neuron-specific enolase (NSE) in CSF. NSE concentrations of more than 35 ng/mL were considered indicative of CJD.

FINDINGS

p130/131 was detected in 81% of definite (47/58), 80% of probable (37/46), 68% of possible (23/34) CJD cases, and in none of the other 44 cases. NSE concentrations of more than 35 ng/mL were seen in 79% of definite (46/58), 80% of probable (37/46), 59% of possible (20/34) CJD cases, and 9% of other cases (4/43). The positive predictive value for 2-DE of CSF is 100% and the negative predictive value is 69%. The level of agreement for the detection of p130/131 by two evaluators in a subset of 141 2-DE gels was a kappa of 0.93 (95% CI 0.86-0.99). Of 13 cases initially classified as possible and later reclassified as definite, ten cases were identified correctly by the 2-DE analysis, indicating a better diagnostic accuracy of this test compared with the current clinical classification. None of nine cases classified as other by neuropathology had p130/131 in 2-DE.

INTERPRETATION

2-DE for p130/131 is a specific test for the diagnosis of CJD. These data suggest including detection of p130/131 as a criterion for the diagnosis of probable CJD in addition to the currently accepted criteria of a rapidly progressive dementia of less than 2 years duration, typical neurological signs, and periodic sharp-wave complexes in the EEG.

Confidence intervals for calibration with neural networks

Based on neural network calibration the confidence intervals of aromaticity determination from infrared reflectance spectra of raw brown coals were estimated by means of the bootstrap method, a simplified Monte Carlo Simulation. The standard deviations and the confidence intervals were estimated to characterise the analysis error.It is shown that confidence intervals of non-linear analysis methods like Back Propagation Neural Networks (BPNN) can be estimated by the bootstrap method. The estimated confidence intervals of the calibration confirm the analysis by BPNN.

Clinical implications of nucleic acid amplification methods for the diagnosis of viral infections of the nervous system

Amplification of viral nucleic acids from the cerebrospinal fluid (CSF) has considerably improved the diagnosis of several acute, subacute and chronic viral infections of the nervous system. In herpes simplex virus (HSV) encephalitis (HSE) the polymerase chain reaction (PCR) has become the method of choice for the rapid, non invasive diagnosis. Other herpes virus associated diseases which can now be reliably diagnosed are encephalitis, ventriculoencephalitis, polymyeloradiculitis, myelitis and an inflammatory polyradiculoneuropathy caused by cytomegalovirus (CMV), HSV, varicella-zoster virus (VZV) or Epstein-Barr virus (EBV), EBV associated primary B-cell-lymphoma of the brain, acute aseptic meningitis in young adults allied with VZV, and meningoencephalitis with recurrent seizures due to human herpes virus type 6 (HHV-6). In AIDS patients, PCR has helped to differentiate lesions either due to the human immunodeficiency virus (HIV) itself or to opportunistic infections such as progressive multifocal leukoencephalopathy (PML) caused by JC virus (JCV) or CMV related complications. HIV can be detected early in the course of infection in the CSF and the amount of proviral DNA in CSF cells seems to be correlated with the severity and/or progression of neurological signs and symptoms. Acute epidemic aseptic meningitis caused by enterovirus infections can now be reliably diagnosed and typed by reverse transcriptase PCR (RT-PCR). Meningitis cases caused by vaccination with the Jeryl Lynn and Urabe vaccine strain of mumps virus have been identified using RT-PCR and sequencing of the amplified products (amplicon).

Six new polymorphic microsatellite markers used for the integration of genetic and physical maps of human chromosome 7

We report the isolation and characterization of six new polymorphic dinucleotide repeat microsatellite markers (D7S1491, D7S1492, D7S1493, D7S1494, D7S1495, and D7S1496), their integration into the genetic map of human chromosome 7 by analysis of 40 CEPH (Centre d'Etude du Polymorphisme Humain) pedigrees, and their use for integration of physical and genetic maps of this chromosome.

[The ultrasound scalpel in laparoscopic surgery]

The ultrasonically activated scalpel works by means of the longitudinally vibrating sharp blade. The most important advantages- compared with electrosurgery-are the lack of current flow through the patient and limited local heat generation. It can be used as an instrument for coagulation, dissection and preparation. There is no generation of smoke. It is easy to use. Disadvantages are the slow speed of cutting and the high costs. In the future it could be an alternative to preparation on with dissector, scissors, and electrosurgery.

?IR-Spectroscopy? ? computer-program for the interpretation of infrared spectra

A computer-program "IR-Spectroscopy" for the interpretation of infrared spectra of organic compounds is described. It contains the following basic items for preprocessing and execution of the computer based interpretation process: handling of the rule-base CorTab, routines for automatic rule generation and interpretation modules on the basis of the programming languages PROLOG and C.

Hypothalamic-pituitary-gonadal axis, prolactin, and cortisol in alcoholics during withdrawal and after three weeks of abstinence: comparison with healthy control subjects

Serum concentrations of luteinizing hormone, follicle-stimulating hormone, testosterone, androstenedione, estradiol, sex hormone-binding globulin, cortisol, and prolactin were measured in 12 male chronic alcoholics once during withdrawal and once after 21 days of abstinence. The results were compared with those of 14 healthy volunteers. During withdrawal, luteinizing hormone, estradiol, and cortisol levels were significantly enhanced. Estradiol and cortisol concentrations fell significantly during abstinence, whereas luteinizing hormone concentrations remained elevated. The results may be interpreted as follows: the well-known inhibitory effect of alcohol on the biosynthesis of testosterone may have led to a compensatory increase in luteinizing hormone secretion, so that normal serum concentrations of testosterone were maintained. On the other hand, peripheral conversion from androstenedione to estradiol via aromatase pathways seemed to be enhanced in chronic alcoholics, at least during withdrawal. Whether this marked increase in estradiol concentrations is implicated in different clinical and psychological symptoms seen in chronic alcoholics remains to be investigated.

Comparative studies on vascular endothelium in vitro. 3. Effects of cytokines on the expression of E-selectin, ICAM-1 and VCAM-1 by cultured human endothelial cells obtained from different passages

Endothelial cells (EC) are very responsive to proinflammatory cytokines, e.g. interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha), as well as to bacterial lipopolysaccharide. EC are stimulated by these substances to secrete chemotactic factors and to increase expression of cell adhesion molecules (CAM), leading to dramatically altered interactions with leukocytes, e.g. granulocytes and monocytes. In these interactions E-selectin, ICAM-1 and VCAM-1 are known to play an important role, as they are presented by the EC and interact with corresponding ligands on the white blood cell membranes. These adhesion molecules have been studied worldwide in a variety of in vitro experiments using cultured EC. Different passages and mixtures of passages have been used in these experiments, often without any regard to the comparability of the results. In this study the expression of E-selectin, ICAM-1 and VCAM-1 on cultured human umbilical vein EC (HUVEC) obtained from different passages (passages 1-6) was studied after 4, 8 and 24 h of exposure to IL-1 beta and TNF alpha. In previous studies, we have shown that IL-1 beta and TNF alpha increase the expression of E-selectin and ICAM-1 on the cytoplasmatic membranes of HUVEC and human adult EC from the saphenous vein and femoral artery in a similar fashion. Using a comparative quantitative cell enzyme immunoassay, we found that the expression of the adhesion molecules was significantly reduced with increasing passages. There was also a decreased persistence of CAM comparing different periods of stimulation between 6 and 24 h in the different passages. These data indicate that the number of passages plays an important role in the expression of adhesion molecules on EC. The results are relevant for the meaningful planning of comparative in vitro studies on EC presentation of CAM.

Methodological Approaches to Biocompatibility and Haemocompatibility Testing of Biomaterials

Die ISO beschreibt Standards zur In-vitro-Testung von Materialien für medizinische oder zahnmedizinische Applikationen hinsichtlich deren Zytotoxizität und Hämokompatibilität. Auf der Basis dieser ISO-Standards erarbeiteten wir eine Reihe von In-vitro-Methoden zur Biomaterial-Austestung, die auf Zellkulturmodellen vor-nehmlich humaner Zellen aufbauen. Dabei werden sowohl Zellinien (z. B. HeLa, L 929 oder THP-1) als auch primär gewonnene humane Zellen (juvenile und adulte, mikro- und makrovaskuläre Endothelzellen, Mesothelzellen, Fibroblasten und glatte Muskelzellen) eingesetzt. Die Biomaterialien werden im Direktkontakt und indirek-ten Kontakt mit der jeweiligen Zellspezies im In-vitro-System getestet. Die Zellen und Materialien sowie ausgeschüttete Mediatoren im Überstand werden mittels einer weitgespannten Palette von Methoden analysiert. Morphologische und ultra-strukturelle Veränderungen werden mittels Licht-, Immunfluoreszenz-, Laser-Scanning- und Elektronen-Mikroskopie untersucht. Funktionelle Parameter von Mediatoren und/oder Oberflächenrezeptoren stellen biochemisch analytische und molekularbiologische Methoden sowie die Flow-Zytometrie dar. Die Verbindung von hier etablierten relevanten In-vitro-Modellsystemen und die Anwendung ultrasensi-tiver analytischer und molekularbiologischer Methoden sind unserer Ansicht nach unabdingbare Voraussetzung für die Durchführung reliabler Biomaterialtestung und garantieren den hohen Wert des Einsatzes dieser Methoden und Modellsysteme.

Comparative studies on vascular endothelium in vitro. 2. Hypoxia: its influences on endothelial cell proliferation and expression of cell adhesion molecules

Recent studies have presented evidence that the processes of hypoxaemia and reperfusion are involved in several pathogenetic mechanisms of atherosclerotic lesions. The ability of hypoxaemia to activate circulating white blood cells (WBCs) and enhance WBC-endothelial cell (EC) interactions is suspected to be a major factor in deleterious processes in the blood vessel wall. Various groups have suggested that cell adhesion molecules (CAMs), such as ICAM-1, VCAM-1 and E-selectin and their leukocyte ligands are involved in intercellular activities of the relevant cell types. We studied the effects of different oxygen tensions, simulating normoxic conditions, hypoxia and hyperoxia in vitro with the help of an umbilical vein EC model in order to determine the effects of oxygenation on CAM presentation on vascular ECs with and without further cytokine and endotoxin (lipopolysaccharides; LPS) stimulation. Semiquantitative analysis of ICAM-1, E-selectin and VCAM-1 was performed using cell enzyme immunoassay techniques. The presentation of ICAM-1, E-selectin and VCAM-1 remained on the whole unaffected by both hypoxia and hyperoxic conditioning after both 7 and 24 h. Stimulation of ICAM-1 by cytokines and LPS was only marginally influenced by the oxygen tension. Cytokine induction of E-selectin was not affected after 7 h and was even reduced under hypoxia, compared to the control culture after 24 h, while stimulation was increased by hyperoxia. VCAM-1 was reduced in both the hypoxic and hyperoxic culture, while being maximally stimulated by cytokines and LPS after 7 h. In general, an effect of hypoxia was not found without any further stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of annexin 33 kDa in cultured cells as a binding protein of influenza viruses

The binding of three influenza A and one influenza B virus strains to proteins of three continuously cultured cell lines was studied using protein overlay and immunostaining methods. The results obtained indicated the presence of both sialic acid-dependent and -independent binding of the virus strains; virus binding to proteins in the molecular mass range from about 40 to 103 kDa was dependent on sialic acid, whereas binding to the 33 kDa protein was independent of sialic acid. The 33 kDa binding protein was identified as annexin, a widely distributed non-glycosylated calcium-dependent phospholipid-binding protein.

[Endemic mercury burden caused by a bleaching ointment in Balken refugees]

In two camps in Ibbenbüren occupied by refugees from Balkan countries we found in 121 inhabitants, among them 56 children, high mercury concentrations in urine and blood. The median of the urinary concentrations was 12 micrograms/l (range: 0.15-770 micrograms/l) or 11.4 micrograms/g creatinin (range: 0.2-446 micrograms/g). 12 adults and 15 children had values above 50 micrograms/l. As source, a mercury-containing bleaching ointment, sold by foreign vendors, was identified. Mercury concentrations in several samples of this ointment ranged from 708 to 17,200 micrograms/g. Similar exposure to mercury may occur elsewhere. Hence, chronic mercury poisoning should by taken into differential diagnostic consideration.

Proximal myotonic myopathy: a new dominant disorder with myotonia, muscle weakness, and cataracts

We describe three families with a dominantly inherited disorder. Affected individuals have myotonia, proximal muscle weakness, and cataracts. There was no abnormal CTG repeat expansion of the myotonic dystrophy (DM) gene in DNA from blood and muscle. The structure of the three families permitted linkage analysis, and there is no linkage to the gene loci for DM or to the loci for the muscle chloride channel disorders or muscle sodium channel disorders. The collection of symptoms in these three families seems to represent a new disorder.

Molecular and genetic characterisation of German families with paramyotonia congenita and demonstration of founder effect in the Ravensberg families

Eighteen German families with a history of paramyotonia congenita (PC) were characterised by genetic and mutational analysis at the SCN4A locus, which encodes the alpha-subunit of the adult skeletal muscle sodium channel. We concentrated our analysis primarily on these families to test the hypothesis that a predominance of one common mutation occurs in all German PC families and that this mutation arose in a common ancestor originating in the North-West of the country. The present eighteen PC families exhibit two different mutations (R1448C and R1448H) on various SCN4A dinucleotide repeat haplotypes and therefore the majority of the mutations probably occurred independently. However, the R1448H mutation is extremely frequent in the North-West of Germany (Ravensberger Land) on a specific SCN4A microsatellite haplotype, indicating a founder effect within this subpopulation. Our results suggest that the R1448C/R1448H mutations are by far the most common to be associated with the PC phenotype in the German population.

Hypothalamic-pituitary-thyroid (HPT) axis in chronic alcoholism. I. HPT axis in chronic alcoholics during withdrawal and after 3 weeks of abstinence

Thyroxine (T4), free T4 (fT4), triiodothyronine (T3), free T3 (fT3), reverse T3 (rT3), thyrotropin (TSH), thyroxine binding globulin (TBG), and T3 uptake were measured in 14 chronic alcoholics during withdrawal and after 21 days of abstinence. Results were compared with those of 16 healthy volunteers. During withdrawal, the fT4 and fT3 concentrations were subnormal, whereas the respective protein-bound fractions were normal. T4, T3, and TBG increased during the abstinence period, T3 and TBG being significantly higher than in normals at the second measuring time. T3 uptake values fell, but remained well within the normal range at both measuring times. During abstinence, the fT3 levels remained significantly lower than in healthy subjects. rT3 concentrations decreased, but not significantly. The TSH values were normal throughout. These results showed numerous abnormalities in the hypothalamic-pituitary-thyroid axis in alcoholics, the reasons for which are as yet unclear. The following possible interpretations are suggested: 1. The abnormally low serum fT3 and fT4 levels during withdrawal might reflect an increase in tissue uptake. 2. The increases in T4--and partly those in T3--during abstinence seem to reflect increased binding by TBG, the level of which rose markedly for reasons as yet unknown. 3. If increases in TBG during abstinence are taken into account, the decreases in rT3 concentrations may reach the level of statistical significance. These falls in rT3 concentrations may reflect an increase in rT3 metabolization (deiodination) in various tissues, including the CNS, leading to a reduction in serum rT3 bioavailability. 4. Factors such as liver disease, protein caloric malnutrition, and "psychological stress" do not fully explain all these abnormalities. A direct effect of ethanol on intracellular thyroid hormone metabolism and/or function seems conceivable.

Application of biotin-streptavidin technology in developing a xanthine biosensor based on a self-assembled phospholipid membrane

We have designed an amperometric xanthine minibiosensor based on a supported biotinylated phospholipid membrane. To this membrane streptavidin-modified xanthine oxidase was coupled. The fabricated biosensor corresponds in shape and size to a needle of 0.3 mm in diameter. The assay is based on the electrochemical detection of enzymatically generated hydrogen peroxide. The response to xanthine was linear up to 1 mmol.l-1 with a detection limit of 0.02 mmol.l-1. The response time was less than one minute and the biosensor was stable for at least five days.

Evidence for genetic homogeneity in autosomal recessive generalised myotonia (Becker)

Generalised myotonia Becker (GM) is an autosomal recessively inherited muscle disorder. Affected subjects exhibit myotonic muscle stiffness in all skeletal muscles with marked hypertrophy in the legs. A transient muscle weakness is particularly pronounced in the arms and hands and is a typical symptom of the disorder. Recently, we showed complete linkage of the disorder GM to the gene (CLCN1) coding for the skeletal muscle chloride channel CLC-1 and the TCRB gene on chromosome 7 in German families. In the study presented here we performed linkage analysis on 14 new GM families. The GM locus was again completely linked to both the CLCN1 and the TCRB gene in all families with a combined lod score of Z = 9.26 at a recombination fraction of theta = 0.00. This confirms our previous data and supports the hypothesis that GM is a genetically homogeneous disorder. The previously detected T to G missense mutation is found on 15% of the 66 GM chromosomes counted so far.

[Traumatic false aneurysm of the subclavian artery]

Injuries of the subclavian artery are rare; still rarer are aneurysms of the subclavian artery due to blunt or penetrating trauma. Diagnosis can be performed by careful clinical investigation. To identify precisely the nature and site of the injury, angiography and CT are necessary. Rarely associated injuries, such as arteriovenous fistulas, can be recognized by means of these diagnostic tools. This will be of value for planning the surgical approach, which varies with the anatomical site of the injury and the kind of accompanying damage. Subclavian aneurysms should be treated surgically, because embolic or thrombotic complications may threaten the extremity and the brain.

Design of a glucose minisensor based on streptavidin-glucose oxidase complex coupling with self-assembled biotinylated phospholipid membrane on solid support

A simple and fast procedure to prepare a glucose-sensitive minielectrode is presented. It is based on a biotin-modified phospholipid bilayer to which a streptavidin-glucose oxidase complex is coupled. The assay is based on the electrochemical detection of enzymatically generated hydrogen peroxide at the potential +670 mV. In the case of an air-saturated buffering solution the response to glucose was measured up to 50 mmol.L-1, with a linear portion up to 7 mmol.L-1. The influence of oxygen tension, pH, and temperature as well as possibly interfering substances was investigated. The prospect usage for the measurement of blood and urine was tested.

The skeletal muscle chloride channel in dominant and recessive human myotonia

Autosomal recessive generalized myotonia (Becker's disease) (GM) and autosomal dominant myotonia congenita (Thomsen's disease) (MC) are characterized by skeletal muscle stiffness that is a result of muscle membrane hyperexcitability. For both diseases, alterations in muscle chloride or sodium currents or both have been observed. A complementary DNA for a human skeletal muscle chloride channel (CLC-1) was cloned, physically localized on chromosome 7, and linked to the T cell receptor beta (TCRB) locus. Tight linkage of these two loci to GM and MC was found in German families. An unusual restriction site in the CLC-1 locus in two GM families identified a mutation associated with that disease, a phenylalanine-to-cysteine substitution in putative transmembrane domain D8. This suggests that different mutations in CLC-1 may cause dominant or recessive myotonia.

[Imipenem in the treatment of patients with severe surgical infection]

The clinical efficacy and safety of intravenously administered imipenem/cilastatin in the treatment of 45 patients with severe bacterial septicemia due to intra-abdominal abscesses, respiratory and urinary tract as well as skin, soft tissue and bone infections was studied in the prospective and open trial. The in vitro antimicrobial activity of imipenem has been assessed on the basis of 909 bacterial strains isolated from patients treated and non-treated with imipenem/cilastatin. Among them were 526 Gram-negative, 370 Gram-positive aerobic bacteria and 13 Gram-negative anaerobic bacteria (Bacteroides sp.). Pathogen susceptibility to imipenem was determined with a disc-diffusion technique using Merck, Sharp Dohme sensitive discs containing 10 mcg of imipenem. Highly sensitive to imipenem were 96.8% of Gram-negative 82.7% of Gram-positive aerobic bacteria and 100% of Bacteroides sp. All patients, in whom evident foci of infection e.g. intra-abdominal abscesses were discovered, were operated on. The dosage of imipenem/cilastatin ranged from 1.5 to 2.0 g/24 h. Clinical cure and bacteriological elimination was achieved in 39 (86.7%) of patients while 6 (13.3%) showed marked clinical improvement. Before and during therapy, aerobic and anaerobic cultures were taken from accessible sites. All specimens were worked up using conventional bacteriological techniques. Before during and after therapy, samples for hematology, biochemistry and urinanalysis were obtained. Adverse clinical effects were noted in 2 (4.4%) patients. One had nausea and vomiting which were probably related to rapid infusion and disappeared after increasing the administration time, and one had transient diarrhea. In conclusion, imipenem/cilastatin was a well tolerated and effective drug in the treatment of life-threatening surgical infections.

[Recanalization of occlusion of the peripheral segment of the femoral artery by the Kensey method]

The aim of the presented study was to analyse the surgical technique and results of recanalization of the peripheral segment of iliac artery with Kensey's technique. Altogether 16 patients were operated. Arterial patency was observed in 14 patients immediately after surgery. This number decreased to 11 after a 3-month follow-up. Complications in the form of perforation of the arterial wall, hemorrhage at the site of puncture and thrombotic lesions in the reconstructed arterial channel were seen in 4 cases. Authors' own experience suggests that Kensey's technique together with laser surgery are the treatment of choice in case of iliac arterial occlusion in patients, in whom classic surgery is contraindicated.

Linkage data suggesting allelic heterogeneity for paramyotonia congenita and hyperkalemic periodic paralysis on chromosome 17

Paramyotonia congenita (PC), an autosomal dominant non-progressive muscle disorder, is characterised by cold-induced stiffness followed by muscle weakness. The weakness is caused by a dysfunction of the sodium channel in muscle fibre. Parts of the gene coding for the alpha-subunit of the sodium channel of the adult human skeletal muscle (SCN4A) have been localised on chromosome 17. To investigate the role of this gene in the etiology of PC, a linkage analysis in 17 well-defined families was carried out. The results (zeta = 20.61, theta = 0.001) show that the mutant gene responsible for the disorder is indeed tightly linked to the SCN4A gene. The mutation causing hyperkalemic periodic paralysis (HyperPP) with myotonia has previously been mapped to this gene locus by the same candidate gene approach. Thus, our data suggest that PC and HyperPP are caused by allelic mutations at a single locus on chromosome 17.

Confirmation of linkage of hyperkalaemic periodic paralysis to chromosome 17

Linkage studies were performed in six European families with hyperkalaemic periodic paralysis (PPII) with myotonia, an autosomal dominantly inherited disorder characterised by episodic weakness. The weakness is caused by non-inactivating sodium channels of reduced single channel conductance of the muscle fibre membrane. Recently, portions of the gene coding for the alpha subunit of the sodium channel of the adult human skeletal muscle (h-Na2) have been cloned and localised on chromosome 17q with no recombinants to the human growth hormone locus (GH1). Linkage between these two chromosome 17 markers and the disease was shown in our families (Z = 7.14, 0 = 0.00). These results, combined with the linkage data of a single large American family, suggest that the disease is caused by dominant mutations of the adult sodium channel, and that it is probably a genetically homogeneous disorder. Hyperkalaemic periodic paralysis is the first non-progressive myotonic disorder to be localised on the human genome.

Focal blockade of single unit synaptic transmission by iontophoresis of antagonists

We have assessed the use of iontophoresis for investigating the pharmacology of synaptic transmission from individual presynaptic neurones in-vivo, by modifying extracellular focal synaptic potentials (FSPs) recorded by spike-triggered averaging. FSPs from two types of excitatory neurone (muscle spindle primary afferents and expiratory bulbospinal neurones) and from one inhibitory interneurone were studied in the thoracic ventral horn of anaesthetized cats. The antagonist of excitatory amino acids at non-NMDA receptors, DNQX, blocked the FSPs from the first two, as did bicuculline for the third. Thus the FSPs were generated by excitatory amino acids acting via non-NMDA receptors and GABA, respectively. The postsynaptic neurones were probably motoneurones. Merits and limitations of the method are discussed.

Quantification of proliferative and suppressive responses of human T lymphocytes following ConA stimulation

The mitogenic response of human T lymphocytes to graded doses of concanavalin A (ConA) has been measured by means of an MTT tetrazolium dye metabolic assay. Three groups of healthy subjects, representing children, younger adults and elderly persons, were investigated. It was shown that a typical bell-shaped course of the ConA dose-response curve is the result of a proliferative response to suboptimal concentrations of ConA and a toxic action of ConA at supraoptimal concentrations. The ascending part of the response curve reflects in its shape the regulatory interaction of responding cells. A decrease in suppressive functions is accompanied by a shift of this part of the curve to lower concentrations of ConA. By means of a mathematical model derived from enzyme kinetics, an attempt was made to quantify the suppressive functions from the course of the individual dose-response curve. It was found that after suitable data processing, suppression-related shape changes can be assigned to a single parameter. The value of this parameter as a diagnostic tool was tested in a study of the age dependence of human T lymphocyte responses to ConA. While the proliferative response decreased with age, the suppressive functions exhibited their maximum effect in the group of adults. Thus it could be demonstrated that ConA induced proliferative and suppressive responses are due to two different pathways which can be independently extracted from the dose-response curve.