Alteration in Bacterial Morphology by Optochin and Quinine Hydrochlorides

Incubation of washed bacterial and ribosomal suspensions with optochin or quinine hydrochloride caused an increase in the turbidity of the suspensions and the appearance of electron-dense cytoplasmic aggregates in the treated cells. These effects were more pronounced with optochin hydrochloride than with quinine hydrochloride, and they did not correlate with the relative sensitivities of different bacteria to growth inhibition by optochin or quinine.     

Implication of Ia-positive bone marrow interstitial stem cells in the induction of unresponsiveness to canine renal allografts

The removal from stored autologous host bone marrow of a monocytoid cell population by exposure to methylprednisolone is associated with successful introduction of unresponsiveness to renal allografts in irradiated recipients reconstituted with such treated marrow. The eliminated cells are a prominent component of the canine long bone marrow interstitium and share a number of important properties with dendritic cells (DC), including size and shape; poor or nonadherence to plastic or glass surfaces; negative staining for neutral esterase, acid phosphatase, or peroxidase; nonphagocytic; Ia positive, but negative for IgG or IgM; ability to act as accessory cells in augmenting the intensity of allogeneic mixed-lymphocyte reactions. Both cell types are of bone marrow origin and are susceptible to steroids in vitro. The results suggest that the bone marrow interstitial cells identified in the course of this study may be enriched with populations of canine dendritic cell precursors and dendritic cells at various stages of differentiation. The detection of a receptor site for Helix promatia on the surface of such cells may be of usefulness in their further characterization and in the analysis of their precise role in the modulation of allogeneic unresponsiveness.     

Aromatase activity in human ovarian cancer

Eighty-four tumor samples from 70 women with primary ovarian cancer were assayed for cytosol estrogen (ERc) and progestin (PRc) receptor concentrations and aromatase activity. In addition, 22 of the tumors were studied for their response to the aromatase inhibitor, 4-OH-androstenedione, in a soft agar clonogenic cell assay system. Although aromatase activity was detected in almost all of the primary tumors, this enzyme was barely detectable in the majority of metastatic tumor samples. There was no significant correlation between aromatase activity and either the ERc or PRc content of the tumors, or tumor grade. Of 12 tumors grown successfully in the soft agar culture system, only 1 showed a substantial (>50%) reduction in colony-forming efficiency after exposure to the aromatase inhibitor. These results suggest that local estrogen biosynthesis probably does not play an important role in the majority of epithelial ovarian tumors. However, there may be a small subset of estrogen receptor-positive tumors in which aromatase could provide a local growth stimulus.     

Survival of shelled acanthors of Moniliformis moniliformis (Acanthocephala) under laboratory conditions

Shelled acanthors (= eggs) of two isolates of Moniliformis moniliformis (Acanthocephala) were tested for their capacity to respond to a hatching stimulus in vitro and for their retention of infectivity to a natural intermediate host (Periplaneta americana). The shelled acanthors were stored for more than 120 weeks (Australian isolate) and for 104 weeks (Texan isolate) together with rat faeces in an incubator maintained at 22.2 +/- 0.1 degrees C. In both cases, infectivity to P. americana was shown to have been retained. In vitro tests of the hatching response were carried out on many occasions during this period of faecal storage. Shelled acanthors continued to respond and no differences were detected either between isolates or within an isolate through time.     

Receptor binding activity of lipid recombinants of apolipoprotein B-100 thrombolytic fragments

Apolipoprotein (apo) B-100, the protein constituent of low density lipoproteins (LDL), is the determinant responsible for LDL binding to the apoB,E(LDL) receptor on cells. The current study was designed to identify the region(s) of apoB-100 that interact with the apoB,E(LDL) receptor. Apolipoprotein B-100 was fragmented by thrombin digestion, and the isolated fragments (T2, T3, T4) were recombined with cholesterol-induced canine high density lipoproteins (HDLc). Before the recombination, the receptor binding activity of apoE of the HDLc was abolished by reductive methylation and extensive trypsin treatment. This treatment permitted almost complete replacement of the small residual apoE fragments by the large apoB fragments. Recombinant apoB particles were isolated by ultracentrifugation and tested for binding to receptors on cultured human fibroblasts. The recombinant particles had chemical and physical properties similar to those of native HDLc. Recombinants of both the whole thrombolytic digest and of isolated fragments displayed specific binding to the apoB,E (LDL) receptor. Anti-apoB,E(LDL) receptor antibodies abolished 90% of the binding, and there was almost no specific binding to receptor-negative fibroblasts or to cells in which the receptors had been down-regulated. The binding of apoB-100 recombinants to the receptor also demonstrated calcium dependency; in addition, the surface binding of the recombinants was released by polyanionic compounds. All these recombinants had binding affinities comparable to one another but less than that of native LDL. Although T2, T3 and T4 recombinants can all bind specifically to the apoB,E(LDL) receptor, it remains to be established whether their activity represents physiologically relevant binding. Nevertheless, the present findings illustrate the potential of the recombinant method using HDLc lipids to reconstitute biological activity.     

Mechanism of Kainate Toxicity to Cerebellar Neurons In Vitro Is Analogous to Reperfusion Tissue Injury

The neuroexcitotoxin kainate has been used as a selective lesioning agent to model the etiology of a number of neurodegenerative disorders. Although excitotoxins cause susceptible neurons to undergo prolonged or repeated depolarization, the proximate metabolic pathology responsible for neuronal necrosis has remained elusive. We report here that kainate-induced death of cerebellar neurons in culture is prevented by inhibiting the enzyme xanthine oxidase, a cellular source of cytotoxic superoxide radicals (O2-.). Moreover, neurons are also protected from excitotoxin-induced death by the addition to the culture medium of either superoxide dismutase or mannitol, which scavenge superoxide and hydroxyl radicals, respectively, or serine protease inhibitor, which forestalls formation of xanthine oxidase. These findings indicate that excitotoxin-induced neuronal degeneration is mediated by superoxide radicals generated by xanthine oxidase, a mechanism partially analogous to that proposed for tissue damage seen upon reperfusion of ischemic tissues.     

Antigenic determinants shared between HLA-A, −B, −C antigens and H-2 class I molecules modified by bovine beta-2 microglobulin

The specificity of the mouse class I-specific antibody COB6-3 was examined in detail. It was found to react with the mouse class I molecules H-2D^b, K^d, and Qa-2, and with human HLA-A, –B, –C antigens. The specificity pattern of COB6-3, despite its different origin, was similar to that of the monomorphic HLA class I-specific antibody W6/32. Cross-inhibition studies show that on human cells the antigenic determinants recognized by the two antibodies are situated close together and may be identical. On mouse cells, reactivity of both antibodies was generated upon replacement of mouse beta-2 microglobulin (B2m) with its bovine counterpart, but differences in specificity were observed using human B2m.Abbreviations used in this paper B2m beta-2 microglobulin - BSA bovine serum albumin - FCS fetal calf serum - FITC fluorescein isothiocyanate - MHC major histocompatibility complex - PBL peripheral blood lymphocytes - PBS phosphate-buffered saline - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis     

Lectin-binding sites in human parathyroid tissue

The aim of this study was to demonstrate several lectin-binding sites in human parathyroid tissue and to correlate these results with functional activity. The following lectins were tested for binding sites with certain carbohydrates (in parentheses): Arachis hypogea (PNA) (galactose), Ulex europaeus I (UEA) (fucose) and concanavalin A (ConA) (mannose). In addition to normal parathyroids used as controls (13 cases), we examined adenomas associated with a clinical picture of primary hyperparathyroidism of differing severity (31 cases), atrophic glands contralateral to a hyperfunctioning adenoma (7 cases), and secondary (renal) hyperplasia (12 cases). Use of PNA (with and without neuraminidase treatment) and UEA yielded negative staining in normal glands, a wide variety of reactions in adenomas, and frequent dense precipitates in atrophic parathyroids, whereas ConA yielded positive staining in all kinds of parathyroid tissue. Assessment of functional activity of adenomas by clinical parameters (pre-operative serum levels of calcium and parathormone) displayed a significant correlation with the semiquantitative grading of the histochemical reactions after PNA and UEA. Lectin-binding sites in parathyroid chief cells of adenomas are believed to indicate some of the cell structures or products directly involved in the secretory process, including degradation. Although ConA may recognize constituent parathyroid glycoproteins, the binding sites for PNA and UEA are thought to be partially associated with secretory glycoprotein (SP-I), as is known from animal experiments. The positive reaction of the atrophic gland may result from degradation enforced by exposure of primarily non-terminal carbohydrate components.     

Auditory and hormonal stimulation interact to produce neural growth in adult canaries

Gonadal hormones can produce striking behavioral and neural plasticity in adult organisms. For example, systemic administration of testosterone to adult female canaries induces the development of male-typical song behavior and results in a striking increase in the size of brain nuclei that are known to be involved with song control. The mechanism whereby androgens produce such neural plasticity is not known, although it has seemed likely that growth-promoting effects of androgens are due to a direct induction of protein synthesis in cells containing hormone receptors (following activation of specific genes by the hormone-receptor complex). In this experiment we have examined the trophic effect of testosterone in the song-control nucleus HVc (caudal nucleus of the ventral hyperstriatum), which has been shown to contain androgen-concentrating cells as well as neurons that are especially responsive to conspecific song. We report here that testosterone administration increases the volume of HVc in hearing adult female canaries only; testosterone-induced growth of HVc is greatly attenuated in birds that are deprived of auditory stimulation via deafening. Thus, testosterone treatment alone is not a sufficient stimulus for neural growth in HVc. This result suggests that testosterone does not stimulate growth solely via a direct action on hormone receptors in HVc, but rather that testosterone and sensory stimulation can act synergistically to produce structural plasticity in the adult brain.     

Why copulatory organs provide so many useful taxonomic characters: the origin and maintenance of hemipenial differences in lacertid lizards (Reptilia: Lacertidae)

The structure of copulatory organs is used very widely in systematics, both for differentiating species and for working out relationships. Differences between taxa may arise from a variety of sources, including non-homology, differences in other parts of the animal, direct selection on copulatory organs, development of physical isolating mechanisms and pleiotropic events. Physical isolating mechanisms seem likely to account for the abrupt differences, involving size, asymmetry and simplifications, that are useful in distinguishing very similar lacertid species. Although these differences usually seem to arise at the end of a speciation event they can simultaneously be the initiating mechanism in a second one. Copulatory organs appear to have high inherent stability, probably resulting from frequent location in strongly homoeostatic environments, single function, insensitivity to niche shift and inertia due to the need to conform to the genitalia of the opposite sex. This stability may be overridden at times by direct selection on the organs themselves or pleiotropic events. Such changes tend to be retained because efficiency in copulation depends not on any absolute genital architecture but on close conformity of the organs. It is the combination of relative stability and tangible input of varied change, which tends to be retained, that so often makes these structures good indicators of relationship.