Drosophilaprojectin: relatedness to titin and twitchin and correlation withlethal (4) 102 CDaandbent-Dominantmutants

We have investigated projectin, a large protein of insect muscles, in Drosophila melanogaster. The 5.3 kilobases of coding sequence reported here contains Class I and Class II motifs characteristic of titin and twitchin, arranged in a three domain ... [II-I-I] [II-I-I] ... pattern. Two mutants mapped to the location of the projectin gene in the 102C subdivision of chromosome 4, lethal(4) 102 CDa and bent-Dominant, have DNA rearrangements within their projectin gene. The lethal(4) 102 CDa mutant has a 141 nucleotide insertion containing stop codons in all three reading frames within an exon sequence, showing that it cannot synthesize normal projectin. Both bent-Dominant and lethal(4) 102 CDa homozygotes die at the completion of embryogenesis because they are unable to escape the egg vitelline membrane. We propose that this hatching failure is due to muscle weakness caused by projectin defects.

Global, behavioral and self ratings of interpersonal skills among adult children of alcoholic, divorced and control parents

OBJECTIVE

The goal of this study is to evaluate interpersonal skills and the relationships among interpersonal skills in a nonclinical sample of adult children of alcoholic, divorced and control parents using a multimethod assessment strategy.

METHOD

Subjects were prescreened to rule out parental psychopathology and maternal alcoholism. Subjects (N = 238, 50% male, 86% white) interacted with a same- or opposite-sex confederate in a series of videotaped roleplays, which were either unstructured or structured via discussion topics and acquaintance instructions. The videotapes were coded for (1) global or general impression ratings of subject and (2) four behavioral components of interpersonal skill: talk, gaze, smile and self-manipulation. Subjects also rated their own skills and anxiety during the roleplays.

RESULTS

Male and female children of alcoholics were judged to be more anxious when interacting with an opposite-sex partner than with a same-sex partner. Children of divorce and controls were not influenced by the gender of their interaction partner. Children of alcoholics were also judged to be less socially skilled then children of divorce. There was some suggestion that children of alcoholics and divorce may not accurately perceive their own level of skill.

CONCLUSIONS

The findings provide some support for interpersonal skills deficits among adult children of alcoholics, although the deficits were not pervasive or consistent across methods. Limitations of the findings and the overall study were discussed.

Alloimmunization after granulocyte transfusions

BACKGROUND

Although granulocyte transfusions are recommended for neutropenic patients with bacterial infections that are unresponsive to antibiotic therapy, the presence of white cell (WBC) antibodies in the recipient can render these transfusions ineffective.

STUDY DESIGN AND METHODS

A 25-year-old man with chronic granulomatous disease experienced a pulmonary transfusion reaction while receiving granulocyte transfusions, and he was found to be immunized to neutrophil antigen NA2. A retrospective study of alloimmunization to HLA and neutrophil antigens in 18 patients with chronic granulomatous disease who had also received repeated granulocyte transfusions was then performed. Sera were tested in lymphocytotoxicity, granulocyte agglutination, granulocyte immunofluorescence, monoclonal antibody immonobilization of granulocyte antigen, and immunoprecipitation assays.

RESULTS

After the granulocyte transfusions, sera from 14 of the 18 patients contained WBC antibodies. Seven sera samples reacted in the lymphocytotoxicity, granulocyte immunofluorescence, and granulocyte agglutination assays; seven reacted in the lymphocytotoxicity and granulocyte immunofluorescence assays but not the granulocyte agglutination assay, and four did not react. When the monoclonal antibody immobilization of granulocyte antigen assay was used, three sera samples reacted with Fc gamma receptor III, three with the 58- to 64-kDa protein carrying the neutrophil antigen NB1, one with CD11a, and one with CD18. Antibodies from three patients immunoprecipitated a neutrophil protein of 60 kDa. Overall, antibodies to neutrophil antigens other than HLA could be detected in sera from eight patients. Transfusion reactions occurred in 11 of the 14 individuals with WBC antibodies and in none of the 4 without antibodies. Seven pulmonary reactions occurred in patients with WBC antibodies. The patients with WBC antibodies were given significantly more granulocyte concentrates (78 +/- 65 vs. 29 +/- 15 units, p < 0.05).

CONCLUSION

Recipients of granulocyte transfusions often become alloimmunized. Screening for WBC antibodies periodically during transfusions, after adverse reactions, or before subsequent transfusions is indicated. If WBC antibodies are present, no further granulocyte transfusions should be given unless the granulocytes are collected from HLA- and/or neutrophil antigen-compatible donors.

Case-control study of sexually transmitted diseases as cofactors for HIV-1 transmission

The aim of the study was to investigate the association between infection with HIV-1 infection and a history of other sexually transmitted diseases (STD). We were able to match 1295 HIV-1 infected patients who attended St Mary's Hospital between 1985 and 1991 with 1273 seronegative controls on gender, sexual orientation, injecting drug use and age at time of test. The cases were 3 times more likely to have a history of ever having had another STD than the controls: multivariate conditional logistic regression showed that, after controlling for sexual behaviour, for known sexual contact with an HIV infected individual or AIDS patient or with a resident from a high HIV prevalence area, area of residence and for year of test, a history of gonorrhoea, syphilis, hepatitis B, genital herpes or genital warts were all significantly associated with HIV-1 seropositive status. These findings reinforce the need for HIV containment strategies to be promoted in conjunction with containment programmes for others STDs.

Identification of a putative membrane-inserted segment in the alpha-toxin of Staphylococcus aureus

To gain a fuller understanding of the regions of the Staphylococcus aureus alpha-toxin important in pore formation, we have used Förster dipole-dipole energy transfer to demonstrate that a central glycine-rich region of alpha-toxin (the so-called "hinge" region) inserts deeply into the bilayer on association of toxin with liposomes. Mutant alpha-toxins with unique cysteine (C) residues at positions 69 and 130 [Palmer, M., et al. (1993) J. Biol. Chem. 268, 11959) were reacted with the C-specific fluorophore acrylodan, which acted as an energy donor. The chosen acceptor was N-(7-nitrobenz-2-oxa-13- diazol-4-yl)-1,2-bis(hexadecanoyl)-sn-glycero-3-phosphoethanolamin e (NBD-PE). Measurement of the degree of donor quenching with increasing NBD-PE in the inner bilayer leaflet enables the distance of closest approach between donor and acceptor to be estimated. For toxin labeled with acrylodan at position 130 (in the hinge region), this distance is approximately 5 +/- 2 A, showing that the probe is close to the inner surface of the liposomes. A second probe labeled at position 69 (in the N-terminal domain) shows negligible energy transfer, indicating a distance of closest approach > 40 A. This implies that this N-terminal region remains "outside" the liposome. We propose a model in which the central region of the alpha-toxin inserts into the membrane and possibly participates in forming the wall of the pore.

Structure of the Aeromonas toxin proaerolysin in its water-soluble and membrane-channel states

Aerolysin is chiefly responsible for the pathogenicity of Aeromonas hydrophila, a bacterium associated with diarrhoeal diseases and deep wound infections. Like many other microbial toxins, the protein changes in a multistep process from a completely water-soluble form to produce a transmembrane channel that destroys sensitive cells by breaking their permeability barriers. Here we describe the structure of proaerolysin determined by X-ray crystallography at 2.8 A resolution. The protoxin (M(r) 52,000) adopts a novel protein fold. Images of an aerolysin oligomer derived from electron microscopy have assisted in constructing a model of the membrane channel and have led to the proposal of a scheme to account for insertion of the protein into lipid bilayers to form ion channels.

Phosphorylation of KSP motifs in the C-terminal region of titin in differentiating myoblasts

Titin is a giant structural protein of striated muscle (M(r) approximately 3000 kDa) and single molecules span sarcomeres from the M- to Z-lines. We have cloned and sequenced the C-terminal region of the titin molecule, which is an integral part of M-lines and forms intimate contacts with the 165 and 190 kDa M-line proteins. In contrast to the regular motif patterns of the A-band portion of titin, the 5.7 kb of titin sequences from the M-line show a complex structure of immunoglobulin-C2 repeats, separated by unique interdomain insertion sequences. As a striking feature, one interdomain insertion comprises four KSP repeats analogous to the multi-phosphorylation repeats of neurofilament subunits H and M. In vitro phosphorylation assays with expressed titin KSP sequences detect high levels of titin KSP phosphorylating kinases in developing but not in differentiated muscle. Since this kinase activity can be depleted from myocyte extracts by antibodies against cdc2 kinase and p13suc1 beads, the titin KSP kinase is structurally related to cdc2 kinase. We suggest that titin C-terminal phosphorylation by SP-specific kinases is regulated during differentiation, and that this may control the assembly of M-line proteins into regular structures during myogenesis.

Titin antibodies in myasthenia gravis: identification of a major immunogenic region of titin

Approximately 15% of patients with myasthenia gravis (MG) have thymus neoplasia. These MG with thymoma (MGT) patients show autoantibodies to striated muscle as well as autoantibodies to acetylcholine receptor. To characterize these thymoma-associated muscle antigens, we cloned a number of immunopositive cDNAs by immunoscreening muscle cDNA libraries with sera from MGT patients. Analysis of the isolated cDNAs show that all share a common sequence encoding a distinct region of the titin gene. We expressed this main immunogenic region (MIR) of titin in Escherichia coli, and determined autoantibody serum titers directed against the obtained recombinant antigen in a variety of patients. We could detect titin MIR autoantibodies in 97% of sera from MGT patients but not in control sera from healthy blood donors. Therefore, expressed titin from the MIR of the molecule is a sensitive marker antigen for evaluating the presence of thymoma in MG.

Kettin, a large modular protein in the Z-disc of insect muscles

Z-discs of insect flight muscle contain a large protein of 500-700 kDa. Monoclonal antibodies label an epitope in the molecule at the Z-disc in Drosophila and Lethocerus (waterbug). A partial cDNA of 1.6 kb from the Drosophila gene has been cloned and sequenced. The corresponding amino acid sequence has a modular structure composed of four conserved repeats of 95 amino acids homologous to immunoglobulin C2 domains (called class II domains in muscle proteins), separated by less conserved linker sequences of 35 amino acids. An expressed class II domain with flanking linker sequences binds to actin and alpha-actinin but not to myosin. Single molecules of the protein would be large enough to span the Z-disc. We suggest that the protein acts as scaffolding in the Z-disc and we call the protein kettin. The Ca2+ activated protease, calpain, disrupts the Z-disc of striated muscle, releasing alpha-actinin intact. Calpain digests kettin to a series of peptides of between 30 and 170 kDa which are released from the myofibril. Digestion of kettin may cause disintegration of the Z-disc and alpha-actinin release which lead to disassembly of the myofibril.

Sequential analysis of marital interactions involving alcoholic, depressed, and nondistressed men

This study was based on the investigators' earlier work on alcoholism and the family and involved a comprehensive assessment of sequential patterns associated with the marital interactions of alcoholic, depressed, and nondistressed men. A total of 131 couples were assessed in a laboratory-based discussion of personally relevant problems. Videotaped observations were conducted during drinking and nondrinking sessions and were subsequently coded according to the Marital Interaction Coding System. Depressed couples were most distinguishable in terms of unique antecedent-consequent patterns, whereas alcoholic and nondistressed control couples were similar to one another and different from depressed couples. Results are discussed in regard to the extant literature on interpersonal theories of depression and alcoholism and in regard to future research needs.

The Staphylococcus aureus alpha-toxin channel complex and the effect of Ca2+ ions on its interaction with lipid layers

Using the techniques of two-dimensional crystallization on supported lipid bilayers together with computer image processing, two distinct two-dimensional crystal types of staphylococcal alpha-toxin complex are formed depending on the presence or absence of Ca2+ ions. Without Ca2+, these are hexagonally packed (in A, a = b = 89.5 +/- 2.5 A; theta = 119.7 degrees) With Ca2+ present, rectangular crystal packing is seen (in A, a = 114.8 +/- 1.6 A, b = 140.2 +/- 0.7 A; theta = 89.1 degrees). A third, banded crystal type is also seen which is interpreted as a side-to-side packing of regular tubules. We use these tubular crystals for cross-correlation searches with top and side-on views of the complex from single particle reconstructions, and with the repeating units from the two-dimensional crystal types. The results lead us to propose a model in which the different two-dimensional crystal types are formed as a result of alpha-toxin hexamers packing in different orientations. In the hexagonal crystals the hexamers lie end-on with a 6-fold axis in projection. On the addition of Ca2+, the hexamers reorient to lie tilted with respect to the support, thus giving rise to a rectangular projection.

Interaction of tetrahydroaminoacridine with acetylcholinesterase and butyrylcholinesterase

This paper examines inhibition of acetylcholinesterase (AchE) and butyrylcholinesterase (BuchE) by tetrahydroaminoacridine (THA), an acridine analog under consideration for palliative treatment of Alzheimer's dementia. THA causes linear mixed inhibition of AchE hydrolysis of acetylthiocholine, a cationic substrate (KI = 3.8 x 10(-9) M), and linear competitive inhibition of AchE hydrolysis of 7-acetoxy-4-methylcoumarin, an uncharged substrate (KI = 6.8 x 10(-9) M), and N-methyl-7-dimethylcarbamoxyquinolinium, a cationic carbamate (KI = 1.5 x 10(-8) M). Propidium association with AchE in the presence of saturating concentrations of THA is characterized by a dissociation constant of 7.7 +/- 0.7 x 10(-6) M, a value within 2-fold of the dissociation constant in the absence of THA. Association of THA with AchE is, therefore, not mutually exclusive with association of propidium at the peripheral anionic site. Moreover, THA causes dissociation of decidium complexes with AchE at concentrations compatible with a dissociation constant of 7.0 +/- 0.4 x 10(-9) M. Similar relationships were observed for THA inhibition of BuchE hydrolysis of butyrylthiocholine (KI = 2.5 x 10(-8) M) and dissociation of decidium complexes with BuchE (KD = 1.9 +/- 0.1 x 10(-8) M). These kinetic and equilibrium data uniformly indicate that THA associates with AchE and BuchE with high affinity and that the subsequent inhibition comes about through ligand association at the active center rather than at a peripheral site. The noncompetitive component of inhibition reflects association of THA with the acyl-enzyme intermediate, with subsequent effects on the rate of deacylation.

Increased detection of HPV 16 virus in invasive, but not in early cervical cancers

Human papilloma virus type 16 (HPV 16) DNA is found in about 50% of cervical squamous cell carcinomas (SCCs), and this association has raised the possibility of a causal role for HPV 16 in cervical carcinogenesis. We have tested this hypothesis by assaying a series of biopsies (n = 119) ranging from normal mucosa to infiltrating SCC with the PCR-technique for the presence of HPV 16 DNA. While HPV 16 DNA was detected in 50% of our cases with invasive SCC, the incidence of HPV 16-positive samples was about 10% in all other biopsies ranging from normal mucosa to cases of carcinoma in situ. HPV 16 therefore appears to be involved in late tumor promotion but not in early tumor development.

Sequential analysis of marital interactions involving alcoholic, depressed, and nondistressed men

This study was based on the investigators' earlier work on alcoholism and the family and involved a comprehensive assessment of sequential patterns associated with the marital interactions of alcoholic, depressed, and nondistressed men. A total of 131 couples were assessed in a laboratory-based discussion of personally relevant problems. Videotaped observations were conducted during drinking and nondrinking sessions and were subsequently coded according to the Marital Interaction Coding System. Depressed couples were most distinguishable in terms of unique antecedent-consequent patterns, whereas alcoholic and nondistressed control couples were similar to one another and different from depressed couples. Results are discussed in regard to the extant literature on interpersonal theories of depression and alcoholism and in regard to future research needs.

Binding and internalization of iodinated neurotensin in neuronal cultures from embryonic mouse brain

The binding and internalization of labeled neurotensin were studied by means of biochemical and light microscopic radioautography techniques in primary cultures of neurons from whole cerebral hemispheres of mouse embryos. Saturable, high affinity neurotensin binding was detected 5-7 days postplating in cells incubated with 0.1 nM 125I-Tyr3-neurotensin at 37 degrees C or 10 degrees C. The binding capacity at equilibrium was 3 times higher at 37 degrees C than at 10 degrees C. Moreover, whereas virtually all the radioactivity bound at 10 degrees C was membrane-bound (i.e. was readily washable by a hypertonic, high pH, NaCl solution), more than 70% of the radioactivity bound at 37 degrees C was intracellular (i.e. resisted the same treatment). Light microscopic radioautograms of whole cells revealed that approximately 16% of neurons were labeled with 125I-Tyr3-neurotensin at either 37 degrees C or 10 degrees C. The labeling was observed over cell bodies and processes, and the density of silver grains associated with perikarya, as compared to processes, was proportionally higher at 37 degrees C than at 10 degrees C. Semi-thin (1 micron thick) sections through cells incubated at 37 degrees C confirmed that a major fraction of the radioactivity was intracellular and showed that it was mainly confined to the cytoplasm. These results indicate that 125I-Tyr3-neurotensin binds to a distinct subset of primary cultured neurons and that a large proportion of the bound radioactivity undergoes rapid internalization in a temperature-dependent manner. It is proposed that this internalization is ligand-induced and that it may play a role in the modulation of central neurotensin receptor levels.

Electron microscopic analysis of the peripheral and membrane parts of mitochondrial NADH dehydrogenase (complex I)

Two related forms of the respiratory chain NADH dehydrogenase (NADH:ubiquinone reductase or complex I) are synthesized in the mitochondria of Neurospora crassa. Normally growing cells make a large form that consists of 25 subunits encoded by nuclear DNA and six to seven subunits encoded by mitochondrial DNA. Cells grown in the presence of chloramphenicol, however, make a smaller form comprising only 13 subunits, all encoded by nuclear DNA. When the large enzyme is dissected by chaotropic agents (such as NaBr), all those subunits of the large form that are missing in the small form can be isolated as a distinct, so-called hydrophobic fragment. The small enzyme and the hydrophobic fragment make up, with regard to their redox groups, subunit composition and function, two complementary parts of the large-form NADH dehydrogenase. Averaging of electron microscope images of single particles of the large enzyme was carried out, revealing an unusual L-shaped structure with two domains or "arms" arranged at right angles. The hydrophobic fragment obtained by the NaBr treatment corresponds in size and appearance to one of these arms. A three-dimensional reconstruction from images of negatively stained membrane crystals of the large-form NADH dehydrogenase shows a peripheral domain, protruding from the membrane, with weak unresolved density within the membrane. This peripheral domain was removed by washing the crystals in situ with 2 M-NaBr, exposing a large membrane-buried domain, which was reconstructed in three dimensions. A three-dimensional reconstruction of the small enzyme from negatively stained membrane crystals, also described here, shows only a peripheral domain. These results suggest that the membrane protruding arm of the large form corresponds to the small enzyme, whereas the arm lying within the membrane can be identified as the hydrophobic fragment. The two parts of NADH dehydrogenase that can be defined by the separate genetic origin of (most of) their subunits, their independent assembly, and their distinct contributions to the electron pathway can thus be assigned to the two arms of the L-shaped complex I.

Immunological approaches to the transmembrane topology and conformational changes of the carboxyl-terminal regulatory domain of yeast plasma membrane H(+)-ATPase

Molecular genetic experiments have suggested that the carboxyl terminus of the Saccharomyces cerevisiae plasma membrane H(+)-ATPase is an inhibitory domain involved in the "in vivo" regulation of the enzyme by glucose metabolism. An antibody prepared against a fusion protein including the last 59 amino acids of the ATPase sequence has been affinity purified to yield a preparation which requires the 18 carboxyl-terminal amino acids for recognition. Antibody binding experiments show that the carboxyl-terminal domain of the ATPase can be selectively exposed by concentrations of the detergent Tween-20 which do not break down the permeability barrier of the plasma membrane to the antibody. Both enzyme-linked immunosorbent assay and immunofluorescence analysis demonstrate that the accessibility of the carboxyl-terminal domain in isolated plasma membranes depends on the physiological state of the cell being increased by glucose metabolism. Immunofluorescence analysis of isolated plasma membrane vesicles, using a dual labeling protocol with concanavalin A and antibody to reveal the orientation of individual vesicles, and colloidal gold immunoelectron microscopy of ultrathin cryosections of whole yeast cells separately demonstrate that the ATPase carboxyl terminus is located in the cytoplasmic compartment. The application of a mutant deleted of the epitope(s) recognized by the affinity purified carboxyl-terminal antibody eliminates the possibility of artifacts arising from nonspecific antibody binding. The accessibility properties and cytoplasmic location of the carboxyl-terminal domain appear to be consistent with its role as a negative regulator of the ATPase.

Evidence that nebulin is a protein-ruler in muscle thin filaments

Partial amino acid sequence was obtained from the massive myofibrillar protein nebulin. This consists of repeating motifs of about 35 residues and super-repeats of 7 x 35 = 245 residues. The repeat-motifs are likely to be largely alpha-helical and to interact with both actin and tropomyosin in thin filaments. Nebulin from different species was found to vary in size in proportion to filament length. The data are consistent with the proposal that nebulin acts as a protein-ruler to regulate precise thin filament assembly.

Experimental drinking procedures in the study of alcoholics and their families: a consideration of ethical issues

In response to G. Koocher's (1991) expressed concerns regarding the use of experimental drinking procedures with alcoholic participants described in our earlier study (Jacob, Krahn, & Leonard, 1991), our discussion focuses on six major issues: risk-benefit analysis, safeguarding participants from harm, linking alcoholic participants with treatment, the use of monetary incentives, fostering the pathology of the alcoholic family, and relationships between alcoholism and adverse family effects. In presenting this material, we hope that readers will become more appreciative of the many implications that human use issues have for the science we pursue and for the welfare of the participants whom we wish to protect.