Immunogenicity of synthetic peptides corresponding to flexible and antibody-accessible segments of mouse lactate dehydrogenase (LDH)-C4

The immunological properties of a panel of synthetic peptides that represent the most accessible and mobile segments of the lactate dehydrogenase (LDH)-C4 molecule were characterized. Peptides corresponding to mouse LDH-C4 amino acid sequences: 1-14b, 5-15, 49-58, 97-110, 211-220, 231-243, 274-286, 304-316, and 318-330 were synthesized and compared in terms of binding antibodies raised in rabbits against the intact protein. Six of these sequences were covalently coupled to diphtheria toxoid and used to immunize groups of rabbits. LDH-C4-specific antibodies were detectable in immune sera by enzyme-linked immunosorbent assay, Western blotting, and immunoprecipitation assays. The immunogenicity of the mouse LDH-C4 peptides in rabbits could be ranked in the following order: 5-15, 304-316 greater than 211-220, 274-286 greater than 49-58, 97-110. The immunological properties of these short synthetic peptides did not correlate with features of the mouse LDH-C4 structure except that the most active sequences appeared to be those that differed from the somatic isozymes to the greatest extent. These results have direct bearing on the selection of immunogenic LDH-C4 peptides for contraceptive vaccine studies in humans and non-human model systems.

Shifts in hemispheric advantage during familiarization with complex visual patterns

Twenty females unfamiliar with kanji were given a recognition task involving tachistoscopic presentation of kanji to the right and left visual fields. Repeated exposure to these novel stimuli resulted in significantly increased competence at the task. To analyze different approaches to the task, subjects were divided into an initial left visual field advantage and an initial right visual field advantage group. Over the course of the experiment subjects in the initial left visual field advantage group shifted from a left to a right visual field advantage, showing both a linear trend and a quadratic trend, while the initial right visual field advantage group showed only a quadratic trend. The results are consistent with observations in other novel stimuli situations which have demonstrated a shift in hemispheric advantage from right to left with increased competence and which have demonstrated individual differences in the pattern of shifting hemispheric advantage.

Changes in body composition during refeeding of patients with anorexia nervosa

Changes in body composition were studied in 13 girls with anorexia nervosa before and during 2 months of refeeding. Fat body mass and fat-free body mass were derived from skin-fold measurements. Total body potassium was measured by whole body counter, and intracellular water was calculated from it. Extracellular water was measured as the bromide space after oral bromide administration. A gradual increase was noted in weight, fat body mass, fat-free body mass, and total body potassium during refeeding. Extracellular water was expanded on admission and increased in all patients in the first weeks of treatment; later it fell to normal. Most of the changes in fat-free body mass over the first weeks of refeeding could be accounted for by an expansion in extracellular water. Particular care must therefore be taken with fluid balance during the first few weeks of refeeding.

Energy expenditure and body composition in patients with anorexia nervosa

Blood biochemistry, body composition, and resting energy expenditure were studied in 25 patients with anorexia nervosa admitted to hospital during a period of 18 months. The patients' ages ranged from 12.9 to 17.2 years, and the abnormal feeding history from 3 to 12 months. Blood chemistry values were in the normal range, but fat body mass and lean body mass were reduced and extracellular water volume was expanded beyond normal values. Resting energy expenditure was reduced to 49% to 91% of values predicted by the Harris-Benedict equations. Substrate use after overnight fast indicated an abnormally high use of carbohydrates. Significant correlations were found between extracellular water volume and triceps skin-fold thickness, mid-arm muscle circumference and lean body mass, and substrate use and weight loss as a percentage of initial weight. We suggest that these simple anthropometric measurements can be used to assess and monitor the refeeding of patients with anorexia nervosa.

High-dose naloxone in tardive dyskinesia

Tardive dyskinesia (TD) is thought to result from nigrostriatal dopaminergic supersensitivity secondary to prolonged neuroleptic exposure. Preclinical studies have demonstrated that the opiate antagonist naloxone can acutely reverse a haloperidol-induced hyperdopaminergic state. In a trial of high-dose naloxone, 20 patients with TD received i.v. naloxone (20 mg, 40 mg, and placebo) under double-blind conditions. At baseline and at regular postdrug intervals, patients were evaluated using a battery of motor, clinical, and neuropsychological measures to study effects on neurological, behavioral, and cognitive functions. There was a significant improvement in involuntary movements at 30 min postnaloxone, together with improvement in clinical ratings at that time point, as well as some cognitive changes. The implications of these findings for the putative functional relationship between dopaminergic and enkephalinergic systems in the nigrostriatal area are discussed.

Localization of a highly divergent mammalian testicular alpha tubulin that is not detectable in brain

Sequence analysis of a mouse testicular alpha-tubulin partial cDNA, pRD alpha TT1, reveals an isotype that differs from both the somatic and the predominant testicular alpha tubulins at approximately 30% of the 212 amino acid residues determined. Although this mouse testicular cDNA retains the highly conserved sequence, Glu-Gly-Glu-Glu, found in the carboxyl termini of many alpha tubulins, the protein extends substantially beyond this sequence and does not terminate with a C-terminal tyrosine. Using rabbit antiserum prepared to a novel synthetic peptide predicted from this mouse testis alpha-tubulin cDNA, we have have detected by immunoblot and indirect immunofluorescence an antigenic epitope present in testicular alpha tubulin that is not detectable in brain alpha tubulins. We find that the antiserum specifically binds to the manchettes and meiotic spindles of the mouse testis but not with neural fibers or tubulin extracts of the adult mouse brain. These results demonstrate that at least one of the multiple alpha-tubulin isotypes of the mammalian testis is expressed and used in male germ cells but not in the brain.

Characterization of the antigenic sites on the refined 3-A resolution structure of mouse testicular lactate dehydrogenase C4

The atomic structure of mouse testicular apolactate dehydrogenase C4 has been refined to 3.0-A resolution yielding a final crystallographic R-factor of 0.256. Comparison with the refined structure of dogfish apolactate dehydrogenase A4 shows that equivalent secondary structure elements are essentially in the same position relative to the molecular 2-fold axes, except for the helices alpha D, alpha E, and alpha 2G in the vicinity of the active center, and the carboxyl-terminal helix alpha H. The positions of antigenic peptides correlate best with surface accessibilities of the monomer rather than of the full tetrameric molecule.

Evaluation of the vasodilator vs inotropic effect of milrinone using an animal model of left ventricular failure: reversal of disopyramide depression of the myocardium with milrinone

Milrinone (M) has been shown to improve left ventricular (LV) performance in animal and human studies. M has strong vasodilator action, and whether increased LV performance is due primarily to vasodilation or to a direct positive inotropic effect is unclear. Ten mongrel dogs were studied. Disopyramide caused a significant and sustained decrease in LV function and was a good model for myocardial depression. At equal reduction in systemic vascular resistance (SVR), M reversed this LV depression to a significantly greater degree than nitroprusside (NP) did. At equal levels of vasodilation, M produced significantly greater improvement in indices of LV function than NP did in our model of disopyramide-induced LV failure. This suggest that its effect on LV function is not due entirely to afterload reduction, or to reflex sympathetic stimulation, but has a substantial component of direct inotropic stimulation. This study also demonstrated a reversal of disopyramide-induced LV dysfunction by M, which may be clinically useful since, as in many antiarrhythmics, myocardial depression may be a limiting factor in its use.

Epitopes of human testis-specific lactate dehydrogenase deduced from a cDNA sequence

The sequence and structure of human testis-specific L-lactate dehydrogenase [LDHC4, LDHX; (L)-lactate: NAD+ oxidoreductase, EC 1.1.1.27] has been derived from analysis of a complementary DNA (cDNA) clone comprising the complete protein coding region of the enzyme. From the deduced amino acid sequence, human LDHC4 is as different from rodent LDHC4 (73% homology) as it is from human LDHA4 (76% homology) and porcine LDHB4 (68% homology). Subunit homologies are consistent with the conclusion that the LDHC gene arose by at least two independent duplication events. Furthermore, the lower degree of homology between mouse and human LDHC4 and the appearance of this isozyme late in evolution suggests a higher rate of mutation in the mammalian LDHC genes than in the LDHA and -B genes. Comparison of exposed amino acid residues of discrete antigenic determinants of mouse and human LDHC4 reveals significant differences. Knowledge of the human LDHC4 sequence will help design human-specific peptides useful in the development of a contraceptive vaccine.

Locus determining the human sperm-specific lactate dehydrogenase, LDHC, is syntenic with LDHA

From the data presented in this report, the human LDHC gene locus is assigned to chromosome 11. Three genes determine lactate dehydrogenase (LDH) in man. LDHA and LDHB are expressed in most somatic tissues, while expression of LDHC is confined to the germinal epithelium of the testes. A human LDHC cDNA clone was used as a probe to analyze genomic DNA from rodent/human somatic cell hybrids. The pattern of bands with LDHC hybridization is easily distinguished from the pattern detected by LDHA hybridization, and the LDHC probe is specific for testis mRNA. The structural gene LDHA has been previously assigned to human chromosome 11, while LDHB maps to chromosome 12. Studies of pigeon LDH have shown tight linkage between LDHB and LDHC leading to the expectation that these genes would be syntenic in man. However, the data presented in this paper show conclusively that LDHC is syntenic with LDHA on human chromosome 11. The terminology for LDH genes LDHA, LDHB, and LDHC is equivalent to Ldh1, Ldh2, and Ldh3, respectively.

Motor perseverations in schizophrenia

Classical neuropsychological descriptions of prefrontal syndromes emphasize qualitative, productive symptoms, among which the phenomena known as motor perseverations occupy a central position. The now popular assertions that selective prefrontal dysfunction characterizes chronic schizophrenia would be more compelling if such productive symptoms could be reliably elicited in these patients. The present study demonstrated the presence of conspicuous motor perseverations in a sample of chronic schizophrenic inpatients, elicited using techniques that were developed and validated in studies of patients with known frontal lobe lesions. The observedperseverations closely resemble, both in severity and typology, those documented in cases with focal damage to prefrontal cortex. The findings support the contention that prefrontal dysfunction exists in chronic schizophrenia.

Non-cross-reactivity of antibodies to murine LDH-C4 with LDH-A4 and LDH-B4

The induction of infertility by immunization with the sperm-specific lactate dehydrogenase, LDH-C4, suggests its use in a contraceptive vaccine. Development of an immunological contraceptive for human use, however, requires that there be no cross-reactions with somatic tissues. We have demonstrated, using enzyme-linked immunoabsorbence, solid-phase radioimmunoassay, and competitive inhibition radioimmunoassay, that antisera to LDH-C4 is specific and does not cross-react with the somatic isozymes, LDH-A4 and LDH-B4.

Varieties of perseveration: a comparison of two taxonomies

Two taxonomies of perseveration have been independently developed by Goldberg and Tucker (1979) and Sandson and Albert (1984). They are in remarkable agreement with respect to phenomenology of perseveration but differ in terms of postulated mechanisms. Sandson and Albert propose a separate mechanism for every type, whereas Goldberg and Tucker propose a unitary mechanism which can operate at different levels of neurocognitive hierarchy thus producing different types of perseveration. The issue of neuroanatomical specificity of perseveration is also addressed. It is proposed that clinical features of prefrontal syndromes need not imply the presence of selective structural or biochemical damage to prefrontal cortex, and that a structurally diffuse CNS disease often masquerades as a selective frontal-lobe disease. The difference between structural and functional definitions of focal brain disease is emphasized.

Local reproductive tract immunity to sperm-specific lactate dehydrogenase-C4

Immunity to sperm-specific lactate dehydrogenase C4 (LDH-C4) results in reduction of fertility in females. Stimulation of a local mucosal immune response to LDH-C4 in the reproductive tract would guarantee the presence of antibodies at the site of fertilization, which should enhance suppression of fertility. After intrauterine immunization with LDH-C4, SJL/J female mice secrete immunoglobulin (Ig)A antibodies specific for LDH-C4 into their uterine fluids. Furthermore, these animals demonstrate a lower pregnancy rate than controls receiving an intrauterine immunization without LDH-C4. Thus, induction of a local immune response is an effective alternative to systemic immunization for administering a contraceptive vaccine.

Control of fertilization by immunization with peptide fragments of sperm specific LDH-C4

The use of a well-defined, synthetic antigen is essential to progress in developing a vaccine for fertility control and to establish with certainty the utility of such technology. The studies with LDH-C4 are consistent with the feasibility of using a synthetic antigen in a vaccine to control fertility. LDH-C4 remains the best-developed candidate for future studies. Immunization with LDH-C4 does suppress fertility, and the complete biochemical characterization of this isozyme is well underway. These studies will provide a wealth of synthetic antigens to substitute for the natural product in experiments to determine whether immunologic contraception is appropriate and desirable for wide-scale application in human beings.

Serum antibodies to LDH-C4

Human sera from the WHO Reference Bank were tested by a liquid phase radioimmunoassay for antibodies to the sperm-specific form of lactate dehydrogenase (LDH-C4; LDH-X). Modestly elevated levels of antibodies were detected in about 10% of infertile males and females and in about 20% of vasectomized males, as well as in a few cases in other categories. The occurrence of this anti-LDH-C4 activity was without overt correlation with other anti-sperm antibody assays. The primary advantage of the radioimmunometric assay is its absolute specificity for a sperm antigen. These findings lend support to contraceptive vaccine development based on LDH-C4 antigenicity.

The antigenicity of synthetic peptide fragments of lactate dehydrogenase C4

Lactate dehydrogenase C4 (LDH-C4) is an antigenic protein found only in spermatozoa and the mature testis. Synthetic peptides containing the amino acid sequences of the C-subunit, designated MC5-15, MC97-110 and MC211-220, were each conjugated to the carrier proteins diphtheria toxoid or bovine serum albumin. Rabbits immunized with these peptide-carrier conjugates produced antibodies to the peptide that cross-reacted with native LDH-C4. These data support our map that identifies antigenic domains of LDH-C4. Such synthetic peptides will be useful in the design of a contraceptive vaccine.

Radiographic pseudofracture of bipolar pacemaker wire

We present a case in which the radiographic appearance of a bipolar pacing lead mimics a wire fracture. Recognition of this normal finding--due to lead construction--will help avoid erroneous diagnosis of wire fracture on chest x-ray films.