Centaur: the system

This paper describes the organization of the CENTAUR system and its main components. The system is a generic interactive environment. When given the formal specification of a particular programming language-including syntax and semantics — it produces a language specific environment. This resulting environment includes a structure editor, an interpreter/debugger and other tools, all of which have graphic interfaces. CENTAUR is made of three parts: a database component, that provides standardized representation and access to formal objects and their persistent storage; a logical engine that is used to execute formal specifications; an object-oriented man-machine interface that gives easy access to the system's functions. CENTAUR is essentially written in Lisp (Le_Lisp). The logical engine is Prolog (Mu-Prolog). The man-machine interface is built on top of the virtual graphics facility of Le_Lisp, itself primarily implemented on top of X-Windows.

The effect of Lambert-Eaton myasthenic syndrome antibody on slow action potentials in mouse cardiac ventricle

Immunoglobulin G (IgG) from Lambert-Eaton myasthenic syndrome (LEMS) patients acts at motor nerve terminal Ca2+ channels. It was injected into mice to investigate effects on cardiac Ca2+ channels. Intracellular recordings were made of slow action potentials in right ventricular muscle cells in the presence of high K+ concentrations and isoprenaline (1 microM). Reduction in Ca2+ concentration reduced the rate of rise and amplitude, but not the duration, of slow action potentials whereas verapamil (1 microM) blocked them. They were not blocked by tetrodotoxin (10 microM), and 4-aminopyridine (1 mM) prolonged the decay phase without affecting the rate of rise and amplitude. The rate of rise, amplitude and duration of slow action potentials were not affected by LEMS IgG. These results show that LEMS IgG does not act on Ca2+ channel currents that underlie slow action potentials in mouse ventricles, suggesting antigenic differences between Ca2+ channels at motor nerve terminals and heart.

Lambert-Eaton myasthenic syndrome IgG depletes presynaptic membrane active zone particles by antigenic modulation

The Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease that can be transmitted from human to mouse with immunoglobulin G (IgG). Electrophysiological studies indicate that LEMS IgG acts on presynaptic voltage-sensitive calcium channels, probably reducing their number, and freeze-fracture electron microscopy demonstrates that LEMS IgG has an effect on the presynaptic active zone particles, which represent putative voltage-sensitive calcium channels. The active zone particles, normally arranged in double parallel rows, move closer together, form clusters, and are reduced in number. The morphological data suggest modulation of the active zone particles crosslinked by LEMS IgG. If this were the case, then only divalent LEMS IgG and F(ab')2 should alter the deployment of active zone particles and monovalent Fab should be without effect. To test this hypothesis, mouse diaphragms were exposed to control and LEMS IgG and IgG fragments in organ culture for 24 hours and then studied by quantitative freeze-fracture electron microscopy. Divalent LEMS IgG and F(ab')2 aggregated and depleted the active zone particles, whereas monovalent Fab had no effect. The findings reconfirm that the active zone particles are targets of LEMS IgG and are direct evidence for modulation of the particles by LEMS IgG. The findings are in harmony with parallel electrophysiological studies of the effects of LEMS IgG fragments on transmitter release in the same diaphragm muscles (Lang et al, J Physiol 1987;390:173P).

HLA-Dw14 and HLA-DR3 haplotypes share a functional determinant recognized by a human alloreactive T-cell clone

In the process of studying the fine specificity of HLA class II molecules, we identified an alloreactive T-cell clone raised to a HLA-Dw14 homozygous cell line that was specifically stimulated by Dw14+ homozygous typing cells but negatively with cells expressing the HLA-Dw4,-Dw10, -Dw13, and -Dw15 subspecificities of DR4. Of interest, this clone was also equivalently activated by stimulation with all DR3 cells and cell lines tested. Negative responses were obtained using a panel of 87 non-DR3 and non-Dw14 cells, including cell lines of the Tenth Histocompatibility Workshop. A monoclonal antibody inhibition study revealed the relevant stimulating determinant to be on HLA-DR molecules in both Dw14- and DR3-positive cells. A comparison of the DR beta 1-chain-inferred amino acid sequences suggests that formation of a topologically equivalent stimulating determinant would involve the participation of two noncontiguous regions of the third diversity region of DR beta 1. The putative recognition conformation detected by the clone is most probably specified by the presence of a valine at position 86 and a nonnegatively charged residue at positions 70, 71, and 74, since these are the only residues where DR3 and Dw14 are distinguishable from all other HLA-DR types. These findings illustrate that the functional ability of class II molecules is not necessarily either illustrated or predicted by serologic typing or by simple considerations of amino acid sequence.

Plasma from myasthenia gravis patients reduces acetylcholine receptor agonist-induced Na+ flux into TE671 cell line

Plasma from myasthenia gravis patients was tested for its ability to inhibit agonist-induced 22Na+ influx into the TE671 cell line that expresses human acetylcholine receptors. Reduced 22Na+ influx correlated weakly with the total anti-acetylcholine receptor antibody level in the plasma, and was also related to the presence of antibody directed against the agonist binding site, as detected by inhibition of 125I-alpha-bungarotoxin binding. However, in some cases there was inhibition of 22Na+ flux without evident anti-alpha-bungarotoxin binding site antibody. We conclude that in most patients antibodies that interfere with 22Na+ influx do so by blocking the agonist binding site. However, in some cases antibodies may be directed at the Na+ ion channel or some important functional determinant.

Metabolism of 3,3'-dichlorobenzidine by horseradish peroxidase

1. The peroxidatic oxidation of 3,3'-dichlorobenzidine by horseradish peroxidase in the presence of H2O2 was examined spectrophotometrically and the reactivity of the spectral species were compared to those formed from the peroxidative oxidation of benzidine. 2. The horseradish peroxidase-catalyzed oxidation of 3,3'-dichlorobenzidine yielded two transient and one stable spectral species with absorption maxima at 630 nm, 370 nm and 410 nm, respectively, whereas that of benzidine yielded three stable spectral species with absorption maxima at 610 nm, 425 nm and 370 nm, respectively. 3. The 425 nm species from benzidine, but not the 410 nm species from 3,3'-dichlorobenzidine was scavenged by butylated hydroxyanisole, glutathione, N-acetylcysteine or 2-deoxyguanosine. 4. H.p.l.c. mass spectrometric analysis, and comparative studies with potassium dichromate oxidation of 3,3'-dichlorobenzidine, indicated that the major product from the horseradish peroxidase-catalyzed oxidation of 3,3'-dichlorobenzidine is azo-3,3'-dichlorobenzidine. 5. None of the products from enzymic or chemical oxidation of either 3,3'-dichlorobenzidine or benzidine was directly mutagenic to S. typhimurium TA98 in the Ames test; however the chemically oxidized and enzymic products from 3,3'-dichlorobenzidine were mutagenic in the presence of H2O2. 6. The data indicate that despite apparent structural similarities between the intermediates formed during the peroxidatic oxidation of all benzidines, the intermediates and products of peroxidatic oxidation of dichlorobenzidine have reactivities and stabilities different from those of other benzidines.

Lambert-Eaton syndrome antibodies: reaction with membranes from a small cell lung cancer xenograft

Lambert-Eaton myasthenic syndrome (LEMS) is a paraneoplastic autoimmune disorder caused by an IgG-mediated reduction in number of presynaptic voltage-gated calcium channels (VGCC) at the neuromuscular junction. In at least 50% of cases, the stimulus for antibody production may be VGCC on small cell lung cancer (SCLC). In this study membranes isolated from a human small cell lung cancer xenograft (Mar), that bound [3H]PN200-110, a VGCC antagonist, were subjected to Western blotting using plasma from 12 LEMS patients and eight controls. Although one band recognised by 3/12 LEMS IgGs might be associated with the VGCC, a number of other proteins were recognised both by LEMS plasma, and by plasma from patients with other disorders. The results illustrate the difficulties found using Western blotting with autoimmune plasma to identify specific polypeptides in a crude antigen preparation.

Stimulation of the conjugation of lipid dienes in hepatic microsomes by 3,3'-dichlorobenzidine

Pretreatment of male rats with 3,3'-dichlorobenzidine (DCB) resulted in the accumulation of conjugated dienes in lipids from hepatic microsomes. In vitro, these microsomes had 2-fold the NADPH-dependent malondialdehyde (MDA)-forming capacity of microsomes from untreated rats. To determine the mechanisms of the DCB-induced accumulation of diene conjugation, the effects of added DCB on NADPH- or iron + ascorbic acid- (Fe2+-ascorbate-) dependent diene conjugation, oxygen uptake and MDA formation were examined in microsomes from untreated rats in vitro. In the presence of NADPH, added DCB stimulated diene conjugation in microsomal lipids as did in vivo DCB pretreatment but inhibited the uptake of oxygen and the formation of MDA. When Fe2+-ascorbate was substituted for NADPH, the formation of diene conjugation, oxygen uptake, and MDA formation were inhibited by added DCB. The DCB-induced stimulation of diene conjugation, in addition to being strictly NADPH dependent, was carbon monoxide sensitive and was concomitant with the binding of added DCB to microsomal lipids. It is postulated that a metabolite of DCB generated by cytochrome P-450 reacts with membrane lipids both in vivo and in vitro in a manner analogous to the initiation of lipid peroxidation but at the same time prevents the autocatalytic decomposition of the lipids. The DCB-induced diene conjugation is interpreted as predisposing to deleterious changes in microsomes.

[Infection of the CNS caused by Listeria monocytogenes]

This report examines two cases of infection of the central nervous system by Listeria monocytogenes (L.m.). Both cases show that listeriosis is not only a differential diagnosis of purulent meningitis, but can also be the cause of an isolated brain stem syndrome with normal cerebrospinal fluid cell count. The prognosis depends crucially on the early antibiotic therapy (ampicillin). The first patient was a chronic alcoholic. He died of fulminant septic shock and meningitis with brain stem encephalitis (cell count of cerebrospinal fluid: 10500/microliters). L.m. was isolated from blood cultures and from cerebrospinal fluid. The second patient had no indications of preexisting immunological disorder. Two days after perianal injections for haemorrhoids, symptoms of a progredient brain stem syndrome developed. The cell count of cerebrospinal fluid was only 10/mu, but L.m. was isolated from blood cultures. The patient died of circulatory failure. At autopsy, a brain stem encephalitis and cerebellitis with inflammation of the surrounding leptomeninx was identified.

The effect of myasthenic syndrome antibody on presynaptic calcium channels in the mouse

1. The action of immunoglobulin G obtained from patients with Lambert-Eaton myasthenic syndrome (LEMS IgG) was investigated by injecting mice, followed by intracellular recordings from the mouse diaphragm. 2. End-plate potential quantal content was studied over a range of Ca2+ concentrations. Curves of log quantal content versus log Ca2+ concentration were shifted to the right by LEMS IgG. For low Ca2+ concentrations, release continued to follow Poisson statistics after LEMS IgG treatment. 3. Miniature end-plate potential (m.e.p.p.) frequency was measured in solutions containing high K+ concentrations. LEMS IgG significantly reduced m.e.p.p. frequency at each K+ concentration studied. 4. M.e.p.p. frequency was measured at fixed high-K+ concentration (15.9 mM) for a range of Ca2+ concentrations. The log-log plot of m.e.p.p. frequency versus Ca2+ concentration was shifted downwards throughout by LEMS IgG. 5. M.e.p.p. frequency was not affected by LEMS IgG in Ca2+-free solutions (K+ concentration 15.9 mM) or in solutions of low Ca2+ concentration (K+ concentration 5.9 mM). 6. At each Ca2+ concentration studied, m.e.p.p. amplitudes were not affected by LEMS IgG. 7. The data suggest that LEMS IgG acts on presynaptic voltage-dependent Ca2+ channels to cause their loss of function, probably by down-regulation.

Lambert-Eaton myasthenic syndrome: II. Immunoelectron microscopy localization of IgG at the mouse motor end-plate

The autoimmune origin of the Lambert-Eaton myasthenic syndrome (LEMS) was documented by passive transfer of its electrophysiological features from humans to mice with IgG. Freeze-fracture electron microscopy has demonstrated a loss of active-zone particles in human LEMS and in its mouse passive transfer model. These data imply that the active zones are targets of the pathogenic LEMS autoantibodies. Immunolocalization of the antibodies has been hindered, however, by a paucity of active-zone particles (about 50/micron2 normally and still lower in LEMS) and by diffusion artifacts in the immunoperoxidase method. To obviate these problems, we employed sensitive avidin-biotin detection systems, both peroxidase and ferritin labels, and quantitative immunoelectron microscopy and end-plate morphometry. We compared mice treated with LEMS IgG, control IgG, and no IgG. In all mice, nonspecific background staining was found in the basal lamina covering the muscle fibers and Schwann cells. When a single 10-mg dose of IgG was injected intravenously, IgG samples from 12 patients produced significant immunostaining of the mouse active zones; from 7 patients they did not. Higher doses of intraperitoneally injected IgG (20 mg, three times a day for 2 days, or 10 mg/day for 15 days) from each of 4 patients (3 of whose IgG previously transferred LEMS to mice) caused significant immunostaining of mouse active zones: (1) the mean density (no./micron presynaptic membrane length) of positive active zones was 0.91 in the immunoferritin study and 0.72 in the immunoperoxidase study (control values, 0.12 and 0.02); and (2) 43% of the ferritin particles in the primary cleft were concentrated at the active zones and the rest were scattered randomly (control value, 5.3%). The findings indicate that LEMS IgG binds to the active zones of the presynaptic membrane.

Antibody heterogeneity and specificity in myasthenia gravis

Anti-AChR is heterogeneous within individuals and between individuals. Anti-AChR idiotypes are not shared to any large extent. Ten monoclonal antibodies raised against human AChR: (a) bind to five partially overlapping regions; (b) are not idiotypically identical even within a region; (c) do not all bind to the main immunogenic region; (d) four distinguish between normal and denervated human AChR; (e) can be used to define the antigenic determinants in MG. Antigenic specificities vary in different clinical groups. Antigenic specificities can change during the course of the disease, but some remain relatively constant. Thymus cultures make antibodies with the same specificity as those present in the serum of the individual. All monoclonal antibodies bind to myoid cells of normal and MG thymus. We find no convincing evidence of naturally occurring antiidiotype antibodies in MG sera.

Lambert-Eaton myasthenic syndrome: I. Early morphological effects of IgG on the presynaptic membrane active zones

In the freeze-fractured presynaptic membrane of the motor end-plate, the active zones consist of two parallel arrays and each array contains 10- to 12-nm particles arranged in two rows. In the Lambert-Eaton myasthenic syndrome (LEMS) and in mice treated with 10 mg/day of LEMS IgG, administered intraperitoneally for several weeks, there was a paucity and disorganization of the active zones, and clusters of 10- to 12-nm particles appeared. To further define the changes in the active zones, mice were studied that had been treated over 2 days with 104 to 180 mg of IgG. Treatment transferred the physiological defect of LEMS. Control mice received normal human IgG or no IgG. The spacing and density (number/unit area) of active-zone particles were evaluated in presynaptic membrane P-faces using computer-assisted stereometry. In the normal active zone, the distance between particles in a given row and between adjacent rows of an array was less than, but the distance between the two arrays was greater than, the distance between the two antigen-binding sites on human IgG. In mice treated with LEMS IgG, the initial alteration in the active zone was a decrease in the distance between particles in a given row and between adjacent rows of an array; the distance between the two arrays remained unaltered. In more affected active zones, the parallel orientation of the rows was disturbed and the arrays became clusters. There was a significantly reduced density of active zones and of large-membrane particles associated with all active zones and clusters.(ABSTRACT TRUNCATED AT 250 WORDS)

Peroxidative activation of 3,3'-dichlorobenzidine to mutagenic products in the Salmonella typhimurium test

The direct and H2O2-dependent mutagenicity of 3,3'-dichlorobenzidine (DCB) were compared in Salmonella tester strains TA98, TA98/1,8-DNP6, TA100 and TA102 using the Ames test. DCB exhibited both direct and H2O2-dependent mutagenicity to both tester strains TA98 and TA98/1,8-DNP6. This H2O2-dependent mutagenicity of DCB was prevented by horseradish peroxidase. DCB, in contrast to its effects in tester strains TA98, was not mutagenic to TA100 and TA102 either directly or in the presence of H2O2. These results suggest that mechanisms, perhaps enzymes endogenous to tester strains TA98, may play a role in the activation of DCB.

Lipid peroxidation dependent aldrin epoxidation in liver microsomes, hepatocytes and granulation tissue cells

Lipid peroxidation activity was determined in liver microsomes, hepatocytes and cultured granuloma cells by measuring ethane and pentane production with an improved capillary gas chromatographic method. Lipid peroxidation initiated by ferrous ions and NADPH produced significantly more hydrocarbons at 4% O2 than under atmospheric (21% O2), hyperoxic or hypoxic conditions. In liver microsomes ferrous ions and ascorbic acid stimulated the non-enzymatic lipid peroxidation and concomitantly the epoxidation of aldrin. The results demonstrate that epoxidation of aldrin can be triggered by the iron initiated lipid peroxidation.

[Pfeifer-Weber-Christian panniculitis (PWCP). Description of a case and review of the literature]

We report on a case of Pfeifer-Weber-Christian panniculitis (PWCP) in a 40 year old woman. PWCP is a rare inflammatory disorder of the subcutaneous fatty tissue. It is characterized by painful relapsing, subcutaneous nodules occurring preferentially at the upper arm, thigh and trunk regions. The disease is often accompanied by recurrent temperatures and constitutional symptoms. The clinical course of our patient had already lasted for four years when we saw her for the first time. Besides local panniculitis of the arms and the trunk she suffered from recurrent temperatures. Antibiotics and/or antiinflammatory therapy failed to control the disease. Laboratory tests and chest X-ray did not reveal noteworthy pathological results. PWCP was proven histologically and distinguished from other soft tissue disorders. The findings are discussed in the context of previous reports. The etiopathology of PWCP remains unclear and a specific therapy still awaits introduction.

[Spontaneous pneumoperitoneum in progressive systemic sclerosis (generalized scleroderma)]

In a twenty-nine year old female patient with progressive systemic sclerosis (scleroderma) (PSS) and an impressing involvement of the intestine (disturbance of the oesophageal motility, pseudo-obstruction, malabsorption) a spontaneous, asymptomatic pneumoperitoneum is observed. Perforation or pneumatosis cystoides intestinalis (PCI) could not be proved. The possible pathogenesis, course, prognosis and therapy of this rare complication are discussed.

Paraneoplastic myasthenic syndrome IgG inhibits 45Ca2+ flux in a human small cell carcinoma line

Certain cancers exert unexplained remote effects on the nervous system. Small cell carcinoma (SCC) of the lung, a tumour capable of spike electrogenesis and which is of possible neural crest origin, is present in approximately 70% of patients with the Lambert-Eaton myasthenic syndrome (LEMS), a disorder characterized by fatigable muscle weakness. Patients with this syndrome have a defect in the (Ca2+-dependent) quantal release of acetylcholine from motor nerve terminals evoked by a nerve impulse or by high K+ (ref.5), and a decreased number of presynaptic active zone particles. The physiological and morphological features of the syndrome can be transferred to mice by the patients' IgG, consistent with an autoantibody interfering with the function of voltage-dependent Ca2+ channels. Here we demonstrate that K+-induced 45Ca2+ flux in a cultured human SCC line is significantly reduced by LEMS IgG, suggesting that in SCC-LEMS an autoantibody to tumour Ca2+-channel determinants is triggered; its cross-reaction with similar determinants at the motor nerve terminal could lead to the remote neurological syndrome.

[Autoimmune hemolytic anemia in ulcerative colitis. Report on 7 cases, possible treatment and review of the literature]

Warm-antibody autoimmune hemolytic anemia (AIHA) is a rare but typical extraintestinal complication of ulcerative colitis. Seven cases with this condition are reported here and 24 further cases from the literature are reviewed. There were no essential differences between the two groups of patients with respect to clinical and immuno-hematological findings. However, the introduction of immunosuppressive drugs has led to a change in therapy and prognosis in recent years. Our observations suggest that treatment with steroids and azathioprine is to be recommended, with accompanying therapy of the underlying disease. In patients failing to respond to this immunosuppressive regimen, splenectomy or surgical treatment of the affected intestines must be considered. For every patient with ulcerative colitis and hyperregenerative anemia the possibility of warm autoantibody formation must be ruled out by performing the direct antiglobulin test.

Action of Lambert-Eaton myasthenic syndrome IgG at mouse motor nerve terminals

We have studied the electrophysiological effects of IgG obtained from four patients with Lambert-Eaton myasthenic syndrome (LEMS) (two with small cell carcinoma), using the mouse passive transfer model. Mice received LEMS or control IgG or plasma, 10 to 60 mg daily. Microelectrode intracellular recordings were made from diaphragm muscle. LEMS IgG and plasma decreased end-plate potential quantal content similarly, confirming IgG as the active factor. LEMS IgG was equally effective in C5-deficient mice, indicating that late complement components are not required. The time course of decline and recovery of quantal content closely followed that of the human IgG in the mouse serum, with time to half-maximal effect of about 1.5 days in each case. Binding/dissociation of IgG or down/up regulation of the antigenic determinants, possibly Ca2+ channels, has a half-life of between 2 and 36 hours. The results confirm our concept that IgG antibody to nerve terminal determinants underlies the disorder of transmitter release in LEMS.

Anti-acetylcholine receptor idiotypes in myasthenia gravis analysed by rabbit anti-sera

Anti-idiotype sera, raised in rabbits against anti-acetylcholine receptor (AChR) (idiotype) purified from the serum of three myasthenia gravis patients, inhibited binding of homologous idiotype to the AChR by up to 80%. The expression of idiotype in the three individuals changed very little over a period of several years, during which they showed a declining trend in overall anti-AChR antibody. Only one of the four anti-idiotype sera inhibited the binding of anti-AChR from a number of other patients. Our results indicate a consistency of idiotype expression within an individual, and fail to show substantial idiotype sharing between individuals.

[In vitro and in vivo studies with interleukin 2 (IL-2) and various immunostimulants in a patient with AIDS]

We report on a lethal course of an acquired immunodeficiency syndrome (AIDS) in a young female patient. She had spent her vacancies six years before diagnosis in Haiti, where a sexual intercourse with a Haitian man had occurred. Leading clinical symptoms consisted of recurrent Herpes simplex infections of the genital and perianal region as well as unexplained high temperatures. There were some typical laboratory and immunologic features of this disease with leukopenia, hypergammaglobulinemia, cutaneous anergy, a reduction of peripheral T-lymphocytes (OKT 3) and an almost complete loss of OKT 4 (helper cells) positive lymphocytes. The mitogenic response upon stimulation with allogeneic cells (MLC) or with the mitogens PHA, Con A and PWM was significantly reduced. There was no measurable interleukin-2 (IL-2) secretion of peripheral blood lymphocytes. Several immunostimulators (thymopentin, inosiplex, bestatin) were tested in lymphocyte proliferation assays in vitro. The mitogenic response could not be enhanced by neither of these substances. A clinical trial with Delimmun (inosiplex) for 14 days did not show any clinical or immunologic improvement in this patient. The intravenous application of high dose immunoglobulin G was without any observable effect. The proliferation inducing capacity of a highly purified IL-2 preparation on the AIDS cells in vitro led us to a clinical trial with this substance. We applied 100 Bödeker units of IL-2 per kg body weight and day subcutaneously for 16 days. A therapeutical effect, however, could not be observed. Cell marker analyses did not show significant changes in lymphocyte subpopulation composition under IL-2 therapy. There was an increase in the spontaneous cell proliferation 14 days after start of IL-2 therapy. The PHA- and IL-2 response of the AIDS cells, however, was unchanged. It cannot be excluded that an administration of IL-2 in earlier stages of AIDS may have beneficial effects.

[HLA typing in patients of German origin with recurrent benign aphthosis and Behçet's disease]

HLA-pattern was analysed in 60 patients with recurrent benign aphthosis (RBA), in another 14 suffering from Behçet's disease (BD) and in 200 healthy individuals, all of German origin. High prevalence rates of HLA-A2, HLA-B5 and HLA-Cw3 haplotypes were found in patients with RBA, yet significant only for HLA-Cw3 (p = 0.01). HLA-B5 was shown in none but two German patients with BD. These results are discussed with particular regard to reports on racial differences of HLA-patterns in the populations of several continents including patients with aphthous disorders.

Passive transfer of Lambert-Eaton myasthenic syndrome in mice: decreased rates of resting and evoked release of acetylcholine from skeletal muscle

Mice were injected for 1-2 months daily with 10 mg immunoglobulin G (IgG) from four patients with Lambert-Eaton myasthenic syndrome (LEMS); control mice were injected with pooled human IgG from normal donors. Gastrocnemius muscles were homogenised for the assay of acetylcholine (ACh), choline acetyltransferase (ChAT), and cholinesterase (ChE). The ACh, ChAT, and ChE contents of gastrocnemius muscles from "LEMS mice" were about the same as the control values, which were 180 pmol, 40 nmol X h-1 (37 degrees C), and 15 mumol X h-1 (37 degrees C), respectively. Hemidiaphragms were treated with an irreversible ChE inhibitor (Soman) and incubated at 20 degrees C for estimation of ACh release. Resting ACh release from experimental muscles was reduced by about 25% (P2 less than 0.05) and the release evoked by 3 s-1 nervous stimulation by 50% (P2 less than 0.05). On the other hand, 50 mM KCl-induced transmitter release was not abnormal in LEMS mice. The findings indicate that IgG antibody from patients with LEMS may bind to nerve terminal determinants that are involved in quantal and nonquantal ACh release.

Passive transfer of Lambert-Eaton myasthenic syndrome with IgG from man to mouse depletes the presynaptic membrane active zones

In the Lambert-Eaton myasthenic syndrome (LEMS), there is a decreased release of acetylcholine quanta from the nerve terminal by nerve impulse. Recently, an autoimmune origin of LEMS was documented by passive transfer of its electrophysiologic features from man to mouse with IgG. Freeze-fracture electron microscopy of LEMS neuromuscular junctions has revealed a paucity of presynaptic membrane active zones. Thus, the active zones might be the targets of the pathogenic autoantibodies in LEMS. To test this assumption, freeze-fracture electron microscopic studies were done in mice injected with 10 mg of IgG daily from each of three LEMS patients and in control mice treated with normal human IgG or no IgG. IgG from patients 1 and 2 impaired neuromuscular transmission in mice, but IgG from patient 3 failed to do so. After 52-69 days of treatment, diaphragm or anterior tibial muscles were removed and coded. Paired muscles from control mice and mice receiving LEMS IgG were studied "blindly." Satisfactory freeze-fracture replicas of 185 presynaptic membrane P-faces were analyzed by stereometric methods. In mice treated with LEMS IgG that was pathogenic by electrophysiologic criteria, there was a selective depletion of active zones and active-zone particles but not of other membrane particles and there was a concomitant increase of large membrane particles aggregated into clusters. These findings provide additional evidence that the active zones facilitate quantal transmitter release by nerve impulse, lend further support to the assumption that the active-zone particles are Ca2+ channels, and establish mediation of the membrane lesions in LEMS by IgG.

Antibodies to motor nerve terminals: an electrophysiological study of a human myasthenic syndrome transferred to mouse

Immunoglobulin G(IgG) prepared from the plasma of patients with a presynaptic disorder of neuromuscular transmission (Lambert-Eaton myasthenic syndrome, l.e.m.s.), or from normal pooled control human plasma, was injected into mice (10 mg daily) for up to 99 days. Micro-electrodes were used to record end-plate potentials from the diaphragm muscle bathed in normal Krebs solution containing tubocurarine (1.0-4.6 microM). At 0.5 Hz nerve stimulation frequency, the quantal content was significantly reduced (P less than 0.01-P less than 0.001) in mice treated with six l.e.m.s. patients' IgG each compared with paired controls. The pooled quantal content was 55 +/- 3 (n = 110 end-plates) for all test animals and 131 +/- 9 (n = 47) for all controls (P less than 0.001). During short trains at 20 or 40 Hz nerve stimulation, control muscles showed marked depression, while test muscles showed either facilitation or less marked depression. Quantal content throughout these trains remained lower than in controls. The results indicate that IgG antibody from l.e.m.s. patients can induce a similar physiologic disorder in injected mice, and they support the view that this antibody interferes with evoked release of transmitter in l.e.m.s. by binding to nerve terminal determinants.

Purification of anti-acetylcholine receptor antibody from patients with myasthenia gravis

The purification of specific anti-acetylcholine receptor antibodies from the plasma of 3 patients with myasthenia gravis was achieved by affinity chromatography using an immunoadsorbent of alpha-bungarotoxin-Sepharose 4B covalently linked to acetylcholine receptor extracted from human leg muscle. The specific antibody was eluted with potassium thiocyanate. The antibody characteristics were monitored throughout the purification procedure. The high avidity of the antibodies for the acetylcholine receptor was preserved but there was some loss of lambda light chain specific antibody.

Fanconi's anemia: anomaly of enzyme passage through the nuclear membrane? Anomalous intracellular distribution of topoisomerase activity in placental extracts in a case of Fanconi's anemia

In cells of Fanconi's anemia (FA) spontaneous breakage of chromosomes was first recognized by Schroeder et al. (1964). Sensitivity to bivalent alkylants has been found to be a constant feature, whereas low levels of several repair-related enzymes have been described in different FA cell lines. In a family with known FA, during a further pregnancy the prenatal diagnosis of the disease was made by cytogenetic analysis of amniotic cells. After birth the fresh placenta was extracted for further enzymologic analysis. An unusual distribution of DNA topoisomerase activity was noted: high in the cytoplasm and only a little activity in the nuclear sap. This contrasts with findings in normal placentae. Since amniotic cells, lymphocytes, and fibroblasts of this child exhibited both high spontaneous breakage of chromosomes and sensitivity to the bivalent alkylant, diepoxybutane, a correlation between the findings on cytogenetic and enzymologic levels is assumed. Whereas in other published cases, a true reduction of activities of enzymes involved in DNA replication and repair has been found, the present results suggest the interpretation that in our patient the genetic anomaly does not affect the level of synthesis of the enzyme itself, but the passage of the enzyme from the place of synthesis (the cytoplasm) to the substrate (inside the nucleus). A genetic anomaly of the nuclear membrane might be a possible explanation, or alternatively, a structural mutation of the enzyme at a site not affecting the catalytic activity, but affecting the membrane passage or intranuclear accumulation. Meanwhile, placentae of two other cases gave similar results, thus supporting our findings.

Autoimmune aetiology for myasthenic (Eaton-Lambert) syndrome

The myasthenic (Eaton-Lambert) syndrome, associated with carcinoma of the bronchus in one patient and with immunological disorders in two others, improved after plasma exchange--observations supported by electromyographic evidence in two cases. Prednisolone and azathioprine treatment led to almost complete remission in one of the non-neoplastic cases and to improvement in the other. The IgG fraction of plasma from all three patients, injected daily (10 mg) into mice for 37-77 days, significantly reduced the initial compound muscle action potential and the quantal content of the end-plate potential measured in the diaphragm, when compared with control human IgG. These results indicate that an IgG autoantibody, binding to nerve terminal determinants, may be responsible for the disorder of neuromuscular transmission in the myasthenic syndrome, and that immunosuppressive drugs may be useful in treating the nonneoplastic form of the disease.

[Role of hormonal receptors in the regulation of the corpus luteum (author's transl)]

Recent publications dealing with the hormonal regulation of the corpus luteum function have been reviewed. Hormones involved in this regulation are: LH and placental analogue hCG, FSH, prolactin and placental analogue hPL, prostaglandins, oestradiol and androgens. The hormone receptor interaction in the luteal cells and the role of each hormone in the modulation of the cell responsiveness has been reviewed.

[Role of hormonal receptors in the regulation of the corpus luteum (author's transl)]

Recent publications dealing with the hormonal regulation of the corpus luteum function have been reviewed. Hormones involved in this regulation are: LH and placental analogue hCG, FSH, prolactin and placental analogue hPL, prostaglandins, oestradiol and androgens. The hormone receptor interaction in the luteal cells and the role of each hormone in the modulation of the cell responsiveness has been reviewed.

Extrachromosomal inheritance in Schizosaccharomyces pombe. III. Isolation and characterization of paromomycin-resistant mutants

In the antimycin--resistant mutant anar-8 of the fission yeast Schizosaccharomyces pombe (Sch.p.) spontaneous mutants were isolated showing high resistance to the aminoglycoside antibiotic paromomycin. All mutants were resistant to the structurally related antibiotic neomycin. Tetrad analysis, mitotic segregation analysis, and mitotic haploidization revealed extrachromosomal, very likely mitochondrial inheritance. In contrast to the rapid segregation of mitochondrial markers in zygotic clones of Saccharomyces cerevisiae (S.c.) the heteroplasmic state of diploids proved to persist for at least 50 generations after zygote formation. Stationary cultures of the paromomycin-resistant mutants parr-106 and parr-112 contain up to 6% respiratory-deficient mutants, but no reversion to paromomycin-sensitivity was observed among 1700-1800 colonies tested. The ability of mutant anar-8 to produce spontaneously respiratory-deficient mutants could be separated from the antimycin-resistant phenotype of anar-8.

Extrachromosomal inheritance in Schizosaccharomyces pombe. I. Evidence for an extrakaryotically inherited mutation conferring resistance to antimycin

In crosses of [ANTr8] with auxotrophic strains, resistance to antimycin segregates almost 50:50 in random spore analysis with a slight preponderance for the sensitivity allele. Tetrad analysis, however, shows all possible types of tetrads (2:2; 3:1; 1:3; 4:0; 0:4 resistant versus sensitive) with an excess of 2:2 segregations and sectoring of colonies on antimycin medium indicating an extrachromosomal mode of inheritance. The overall ratio of resistant versus sensitive spores is the same as compared with random spore data. Using a mutant blocked in meiosis (mei 1) mitotic segregation of stable diploids is achieved, leading to a ratio of 20% resistant to 80% sensitive clones. Possible reasons for the bias in transmission of the resistance determinant is discussed.

Extrachromosomal inheritance in Schizosaccharomyces pombe. II. Evidence for extrakaryotically inherited respiratory deficient mutants

In contrast to the wild-type, mutant [ANTr8] is able spontaneously to throw off stable respiratory deficient mutants. The frequency of these mutants is considerably enhanced by treatment with ethidium bromide (EB) or the azo-dye Janus green (JG). An unstable cell state with a petite-like phenotype is found in both mutant [ANTr8] and wild-type after EB-treatment. However, only in the mutant is this unstable cell state followed by the appearance of stable respiratory deficient (RD) mutants. Formation of microcolonies is observed both in [ANTr8] and wild-type. RD mutants were isolated after EB treatment. Three of them (mit-12, mit-25, and mit-30) were analyzed and mit-25 characterized in more detail.