Immunodiagnostic tests for Lyme disease.

Standardized serologic tests for Lyme disease are needed, as isolation or in situ demonstration of the spirochete has proved difficult. At the Centers for Disease Control (CDC), an indirect immunofluorescence assay (IFA) was modified from a previously described IFA, and an enzyme-linked immunosorbent assay (ELISA) was developed with soluble spirochetal antigens. Both tests were evaluated with sera from Lyme disease patients, normal controls, and patients with other diseases. They were highly specific for Lyme disease when sera from patients with syphilis were excluded. Sensitivity varied with disease stage: for patients with erythema chronicum migrans alone, the IFA was 53 percent sensitive and the ELISA was 67 percent sensitive. In contrast, all patients with complicated Lyme disease had at least one serum specimen positive in both tests. Twenty-six percent of the sera from 289 patients with suspected Lyme disease that were submitted to CDC in 1983 had IFA titers greater than or equal to 256 and thus were considered positive. Both tests should be useful diagnostic and epidemiologic aids.     

Indications for Vena Caval Fenestration

A retrospective study of 20 patients who underwent vena caval fenestration showed that in 50% of the patients the procedure was done for prophylaxis and in 50% it was done for therapeutic reasons. After this procedure five patients had persistent leg swelling, two had deep venous thrombosis, two had pulmonary emboli and one died of a respiratory arrest. We recommend limiting the use of vena caval fenestration to those patients who have verified pulmonary embolism while adequately anticoagulated or patients who have pulmonary embolism and a major contraindication to anticoagulation.     

Binding of protein chemotactic factors to the surfaces of neutrophil leukocytes and its modification with lipid-specific bacterial toxins

Summary The binding to neutrophil leukocytes of human serum albumin (HSA), which is chemokinetic for leukocytes, i.e. influences their rate of locomotion, and of alkali-denatured HSA, which is chemotactic for leukocytes, i.e. influences their direction of locomotion, was studied. Native serum albumin showed low affinity binding to the neutrophil surface. Denatured serum albumin showed saturable binding with a K_a of approximately 10⁶ litres per mole to about 10⁶ binding sites per cell. Another protein chemotactic factor, _s-casein, gave similar binding. These results exclude that chemotactic reactions to denatured proteins are mediated in a completely non-specific manner and suggest the presence on the cell of a restricted number of defined recognition sites. Binding was reduced following treatment of the cells with either of two lipid-specific bacterial toxins, perfringolysin, the -toxin of Clostridium perfringens, an oxygen-labile cholesterol-specific toxin, and Staphylococcus aureus Sphingomyelinase C. Both have previously been shown to reduce chemotactic reactions and both were used at doses which did not reduce cell viability. These results suggest an important, and possibly direct, role for membrane lipid in the binding sites for chemotactic factors. Visual analysis of the behaviour of perfringolysin-treated neutrophils showed that these cells were still capable of chemotactic locomotion. The cells appeared to be less efficient than normal in detecting chemotactic gradients only when at a distance from the gradient source, a finding which is consistent with reduced binding of the chemotactic factor to the cell surface.     

Isolation and characterization of isocitrate lyase from a thermophilic Bacillus sp.

Isocitrate lyase was isolated in homogeneous state from a thermophilic Bacillus. The enzyme has a mol.wt. of 180000 and a pI of 4.5 and contains threonine as the N-terminal residue. It resembles in size the cognate enzyme from the mesophilic bacterium Pseudomonas indigofera, but is smaller than the enzyme from the eukaryotic fungus Neurospora crassa. All three lyases are tetramers and similar in amino acid composition, but the thermophile enzyme is distinctive from its mesophilic coutnerparts in possessing a lower catalytic-centre activity, greater resistance to chemical and thermal denaturation and fewer thiol groups and in being strongly activated by salts. Salt activation, by 0.4M-KCl, is about 3-fold at 30 degrees C and pH 6.8 and weakens progressively as the temperature or pH is raised. The activation is probably due to a change in the enzyme conformation caused by the electrolyte modifying the interaction between charged groups or between hydrophobic groups in protein. The possible significance of the salt activation, of the relative paucity of thiol groups and of the greater resistance to chemical denaturants is discussed. Besides its effect on the Vmax., KCl produces large increases in the magnitude of several kinetic parameters. A rise in reaction temperature from 30 to 55 degrees C produces a somewhat similar result. In view of these peculiar features, the patterns of inhibition of enzyme activity by compounds such as succinate and phosphoenolpyruvate were examined at 30 and 55 degrees C in the presence and absence of KCl.     

Vocalizations of chicks and juveniles and the development of adult calls in the Aldabra White-throated rail Dryolimnas cuvieri aldabranus (Aves: Rallidae)

Calls were recorded from eggs, chicks and juveniles of the Aldabra White-throated rail Dryolimnas cuvieri aldabranus. A sonagraphic analysis was made of these calls, their behavioural contexts described and probable functions suggested. Three calls, the twitter, tiuu and contented peep were produced by chicks in the egg. All three calls may be derived from the basic peep first recorded some 36 hours before hatching. Shortly after hatching two more calls, the distress call and the alarm call, can be elicited from the rail chicks. Contented peeps and twitters are restricted to the repertoire of young rails. Song was first heard from wild rail chicks at the age of ten days and may develop from the contented peep. Three adult calls, the 'mp yeah, 'mptiuu and 'mpclick appear at the age of three months and six months later the adult vocal repertoire is completed by the appearance of 'mps, toks, purrs and nest-defence squeals. With the exception of the 'mp, all adult calls can be derived from the vocalizations of chicks and juveniles.     

Characterization and identification of coagulase-negative, heat-stable deoxyribonuclease-positive staphylococci

Various characteristics of 13 coagulase-negative, weakly heat-stable deoxyribonuclease-positive staphylococci from human, veterinary and food sources were determined in an effort to identify them. Nine of the isolates were identified as coagulase-negative Staphylococcus aureus (2), Staphylococcus xylosus (2), Staphylococcus simulans (3), Staphylococcus capitis (1) and Staphylococcus sciuri subsp. lentus (1); the other four isolates, from food and veterinary sources, could not be identified as currently accepted or proposed species. Teichoic acid and peptidoglycan compositions were used as key taxonomic characteristics. The determination of heat-stable deoxyribonuclease activity can be useful to detect coagulase-negative S. aureus strains. However, this activity also appears to be present in strains of other staphylococcal species.     

Cold pressor test in diagnosis of coronary artery disease: echophonocardiographic method.

The cold pressor test was used to induce myocardial ischaemia in patients with coronary artery disease and the rise in left ventricular filling pressure used as the index of myocardial ischaemia. Left ventricular filling pressure was derived from a non-invasive echophonocardiographic method. A study group of 19 consecutive patients with chest pain underwent the cold pressor test before coronary angiography. Eighteen responded with a rise in filling pressure exceeding 30% and, of these, 17 had serious coronary artery disease (three single vessel, one two vessel, and 13 triple vessel disease; one had coronary artery spasm only). The remaining patient, who showed no rise in filling pressure, did not have coronary artery disease. None of 15 normal controls showed a rise greater than 5% (patients with coronary artery disease versus normal controls p less than 0.001). The cold pressor test would be suitable for patients who cannot or should not exercise and may be combined with exercise electrocardiograms to improve the information content, as it uses a different marker of myocardial ischaemia.     

Flunitrazepam binding sites in rat diaphragm. Receptors for direct neuromuscular effects of benzodiazepines?

The evidence for direct muscle relaxant effects of benzodiazepines is controversial. We now show that a crude membrane preparation of rat diaphragm possesses binding sites for [3H]flunitrazepam (FNZ). Scatchard analysis gave a binding site density of 1689 +/- 143 fmol/mg protein (Kd = 25.6 +/- 2.6 nM). These sites are of the "peripheral" type since clonazepam fails to displace [3H]FNZ as effectively as R05-4864 (IC50 values: 7.5 x 10(-6) M and 8 x 10(-9) M, respectively). Diazepam is almost as effective as R05-4864 and potently displaces [3H]FNZ binding (IC50 = 3 x 10(-8) M). We propose that the previously described effects of diazepam on rat diaphragm are mediated through high-affinity binding sites.     

The chromosomal component of reproductive isolation in the grasshopper Caledia captiva

An analysis of the relative viabilities of recombinant and nonrecombinant chromosomes among the surviving embryos from back-crosses involving the Moreton (M) and Torresian (T) taxa has revealed that these embryos do not contain a representative sample of gametes derived from the F₁ hybrid parent. The significant deviations in the hybrid gametic population arise entirely from intrachromosomal effects with no evidence of any between-chromosome interactions. This is interpreted as clear evidence to show that recombinational repatterning within heterozygous bivalents in the F₁ parent is a significant factor in inducing the observed deviant segregation ratios. Furthermore, by using a population which is chromosomally equivalent to the Torresian but genically similar to the Moreton, it has been shown that over 46% of the F₂ embryonic breakdown arises solely from the effects of chromosomal heterozygosity upon recombination repatterning among (Moreton × Torresian) F₁ hybrids. From these data it is proposed that each chromosome is internally coadapted in the sense that it contains balanced blocks of cis-acting acting loci which can be disrupted by recombinational change. Disruption of the linear association of the genes on structurally different chromosomes by recombination repatterning results in novel intrachromosomal associations which may be functionally inadequate and so lead to arrested embryonic development. It is speculated that an important factor in arresting development may involve interactions between the novel recombinant chromosomes of the gamete and maternal factors laid down in the egg during oogenesis which are responsible for the sequential activation of the genomes of the progeny during development. Thus coadaptation is interpreted in terms of the functional intergration of a chromosome with the products of the genome of the previous generation. The assessment of the relative viabilities of recombinant and nonrecombinant chromosomes has shown that the Torresian nonrecombinant chromosomes possess the highest viabilities in the sequence T^N>M^NT^R = M^R where N and R represent nonrecombinant and recombinant classes. This sequence is relevant to the structure of the hybrid zone between the Torresian and Moreton taxa and explains both its asymmetry and the basis of the observed introgression of Torresian chromosomes into the Moreton taxon and the absence of the reverse movement.