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Biomedical subjects

J N Miller

Publications and source records attributed to J N Miller.

At least 127 records · Page 7Linked to original sources
PubMed1980

Host response to Treponema pallidum in intradermally-infected rabbits: evidence for persistence of infection at local and distant sites.

Intradermal infection of rabbits with Treponema pallidum imitiates rapid and active cellular response at the site of injection. During the first 2 weeks following infection, there is a marked increase in the numbers of organisms at the site of infection. Systemic dissemination of treponemes occurs during the early stage of infection, presumably before the immune response is fully mobilized. The mononuclear infiltration, which is apparent at the lesion site one week postinfection, becomes more pronounced at 2 weeks. The infiltrating cells are predominantly T lymphocytes and macrophages. By 4 weeks postinfection, most of the organisms have been cleared from the primary site; however, low numbers of treponemes survive locally and in distant tissues. Thus, whereas infection with T. pallidum appears to activate immune mechanisms which are capable of clearing most of the organisms from the primary lesion, some organisms are able to evade these mechanisms and persist in vivo.

Animals↗
PubMed1980

Long-term incorporation of tritiated adenine into deoxyribonucleic acid and ribonucleic acid by Treponema pallidum (Nichols strain).

Treponema pallidum (Nichols strain), extracted in medium containing Eagle minimal essential medium 50% fresh, heat-inactivated normal rabbit serum, and 1.0 mM dithiothreitol, was incubated under 3% oxygen in the presence of tritiated nucleic acid precursors. [8-3H]adenine was incorporated with high efficiency into trichloroacetic acid-insoluble material; 2'-deoxyadenosine and uridine were incorporated in lower quantities, and thymine and thymidine were not incorporated. Incorporation of [3H]adenine was inhibited by penicillin G, mitomycin C, actinomycin D, and erythromycin, but was not affected by cycloheximide. Partial purification of nucleic acids from T. pallidum incubated with [8-3H]adenine for 36 to 72 h and subsequent treatment with ribonuclease and deoxyribonuclease revealed that 15 to 20% of the trichloroacetic acid-precipitable counts were resistant to ribonuclease but susceptible to deoxyribonuclease. A simple assay was developed in which NaOH treatment was used to distinguish incorporation into ribonucleic acid and deoxyribonucleic acid. Both ribonucleic acid and deoxyribonucleic acid synthesis continued for 6 days of incubation under 3% O2, whereas incorporation was limited to the first day of incubation in samples incubated under aerobic or anaerobic conditions. T. pallidum thus appears to be capable of significant de novo deoxyribonucleic acid and ribonucleic acid synthesis under microaerobic conditions.

Adenine↗
PubMed1978

Nitrogen-oxygen saturation therapy in serious cases of compressed-air decompression sickness.

Decompression sickness and arterial air embolism which follow exposure to raised environmental pressures of compressed air are usually adequately treated by accepted recompression procedures of relatively short durations. With serious cases, however, conventional treatment may not allow sufficient time at depth for the complete resolution of manifestations because of the need to avoid pulmonary oxygen toxicity which is associated with a prolonged period of breathing compressed air. Treatment by nitrogen-oxygen saturation at a pressure equivalent of 30 m (100 ft) sea water is proposed. Based upon the success of three refractory cases treated by this procedure, recommendation are made for the conversion of standard compressed-air chambers into an emergency saturation mode for therapy.

Adult↗
PubMed1978

Alterations in plasma norepinephrine concentration during surgical resection of pheochromocytoma.

Using a sensitive and specific radioenzymatic assay, the plasma norepinephrine (NE) concentration was measured in seven patients with pheochromocytoma, one patient with bilateral adrenal medullary hyperplasia, one patient with a retroperitoneal paraganglioma, and two patients undergoing bilateral adrenalectomies for palliation of metastatic breast carcinoma. Surgical manipulation of the pheochromocytomas resulted in striking increases in plasma NE concentration with concomitant increases in blood pressure. There were either small changes or no changes in the patients' plasma NE and blood pressure during resection of the normal adrenal glands, the adrenal glands with medullary hyperplasia, or the retroperitoneal paraganglioma. Plasma dopamine-beta-hydroxylase (DBH) was measured in one patient with pheochromocytomas and the patient with medullary hyperplasia. There was no change in plasma DBH in either patient, supporting the concept that exocytosis is not the primary mechanism for catecholamine secretion from pheochromocytomas. It was also noted that enflurane is an excellent general anesthetic for the resection of pheochromocytomas, and that sodium nitroprusside (rather than phentolamine) may be the agent of choice for the management of the hypertensive episodes that occur during surgical manipulation of pheochromocytomas.

Adolescent↗
PubMed1978

Microassay for immunoglobulin G antibodies to Treponema pallidum with radioiodinated protein A from staphylococcus aureus: immunoglobulin G response in experimental syphilis in rabbits.

Radioiodinated staphylococcal protein A (SpA) was used to detect the immunoglobulin G (IgG) antibody response to Treponema pallidum in experimental syphilis. This solid-phase assay is based on the principle that SpA binds avidly to the Fc portion of mammalian IgG. The optimal number of organisms for detection of antibody was 10(5) per microwell. Of eight fixatives, 10% ethanol gave an optimum immune binding ratio of infected to normal rabbit serus at a 1:100 serum dilution. Kinetic studies demonstrated maximum binding and the highest immune binding ratio (15:1) with a 60-min incubation each for antibody and (125)I-SpA, respectively. The IgG response in rabbits intratesticularly infected with live T. pallidum and bled at -1, 9, 30, 90, 180, and 480 days was detected first at 9 days, reached a peak at 30 days, and remained elevated for 480 days. Absorption studies with an extract of T. phagedenis biotype reiterii demonstrated that 65 to 85% of the total antitreponemal IgG response was specific for T. pallidum throughout the course of infection. The microassay was quantitative and detected less than 2 ng of antibody.

Animals↗
PubMed1978

Influence of oxygen tension, sulfhydryl compounds, and serum on the motility and virulence of Treponema pallidum (Nichols strain) in a cell-free system.

The motility and virulence of Treponema pallidum (Nichols strain) were monitored during incubation in a modified tissue culture medium to study the effects of oxygen tension and medium composition on survival of the organism. A basal medium of Eagle minimal essential medium with 50% fresh, heat-inactivated normal rabbit serum was used inasmuch as better survival occurred with 50% normal rabbit serum than with lower concentrations. Addition of 0.5 to 2.0 mM dithiothreitol or 2.0 mM dithioerythritol to the basal medium led to significantly longer retention of T. pallidum viability in the presence of 3% oxygen than under aerobic or anaerobic conditions. The results of this investigation lend support to the classification of T. pallidum as a microaerophilic organism and provide direction for the design of potentially successful culture systems, with or without tissue culture cells.

Blood↗
PubMed1978

Demonstration of the in vitro phagocytosis of Treponema pallidum by rabbit peritoneal macrophages.

Evidence has been provided for the in vitro phagocytosis of virulent Treponema pallidum by stimulant-induced peritoneal macrophages. After the 4-hr incubation of macrophages with T. pallidum, treponemal antigens associated with the macrophages are specifically stained using indirect immunofluorescent techniques. Phagocytized treponemes appear within the cytoplasm of macrophages as round, brightly fluorescent "bodies" observable in increasing numbers as the duration of the treponeme-phagocyte interaction increases. Their presence is significantly reduced in the cytoplasm of macrophages that have been treated with cytochalasin B, a known inhibitor of phagocytosis, and in nonphagocytic fibroblasts. Additionally, supportive evidence for T. pallidum phagocytosis in vitro has been provided by electron microscopic examination in which treponemes have been demonstrated within typical phagocytic vacuoles. This study also provides evidence that immune serum factor(s) significantly promote the phagocytosis of T. pallidum, although a contribution by heat-labile serum factors has not been demonstrated. The possible mechanisms of immune serum contribution and the implications of the demonstration of T. pallidum phagocytosis are discussed.

Aerobiosis↗
PubMed1977

Interaction of Treponema pallidum (Nichols strain) with cultured mammalian cells: effects of oxygen, reducing agents, serum supplements, and different cell types.

Cultured mammalian cells extend the time of survival of Treponema pallidum (Nichols strain). Various parameters that have been previously shown to enhance treponemal survival in vitro were examined for influences on the interaction of T. pallidum with cultured cells. With cells derived from normal rabbit testes, the time of retention of treponemal virulence was extended in an atmosphere containing reduced concentrations of oxygen. Glutathione and cysteine, when added to the basal tissue culture medium, prolonged treponemal survival. In an assessment of various tissue culture medium supplements, normal rabbit serum was equivalent to fetal bovine serum and superior to bovine serum albumin fraction V (BSA), fatty acid-poor BSA, and lipid-pooed for TRK-2, HSE, NRK, and C6 cells. Dithiotreitol, as an additional reducing agent, sharply enhanced treponemal survival. With SF1Ep NBL-11 cells and basal tissue culture medium containing glutathione, cysteine, and dithiothreitol, in an atmosphere of approximately 3% oxygen, T. pallidum was maintained without detectable decreases in the number of virulent organisms for 6 days.

Blood↗
PubMed1977

Characterization of the attachment of Treponema pallidum (Nichols strain) to cultured mammalian cells and the potential relationship of attachment to pathogenicity.

The interaction of Treponema pallidum (Nichols strain) with 19 different cultured mammalian cell types was examined. These types included cells derived from testis, kidney, spleen, lung, epidermis, cervix, urethra, and nerve tissue of human, rabbit, or rat origins. They represented normal and malignant cells, epithelial and fibroblastic morphology, cell lines, and cell strains, Large numbers of organisms attached to the cultured cells; this attachment prolonged the time of retention of active treponemal motility. Attachment was examined in terms of the number of treponemes inoculated, cultured cells present, and actively growing versus stationary cultured cells; the motility of the treponemes; the viability of the cultured cells; and the different cell passages. In sharp contrast to the attachment of T. pallidum, 11 nonpathogenic treponemes failed to attach to cultured cells. Immune syphilitic rabbit serum prevented the attachment of T. pallidum to cultured cells, as indicated by phase contrast microscopy and rabbit inoculations. This blockage of attachment by immune serum occurred without interfering with active motility of the organisms. Results are discussed in terms of the potential relationship of attachment to the pathogenicity of T pallidum.

Antibodies, Bacterial↗
PubMed1977

Scanning electron microscopy of Treponema pallidum (Nichols strain) attached to cultured mammalian cells.

This paper describes the attachment of Treponema pallidum (Nichols strain) to cultured mammalian cells as a visualized by scanning electron microscopy. Treponemes were incubated for 3 hr with cultured cells derived from normal rabbit testes or human skin epithelium, then fixed, processed with critical-point drying, and examined with a Cambridge Mark 2A scanning electron microscope. Large numbers of treponemes became attached to the cultured cells without altering the morphological integrity of the cultured cells. Attachment appeared to involve a very close physical proximity of treponemes to the cultured cells; at the site of attachment, no changes such as swelling or indentation of the cultured cell surface were observed. The addition of ruthenium red to the fixatives produced a treponemal-associated surface precipitate. This material, which is probably mucopolysaccharide and/or phospholipid, may be important in protecting the organisms against host defense mechanisms; in addition, it may be involved in the serological unresponsiveness of freshly prepared suspensions of T. pallidum.

Animals↗
PubMed1976

Factors affecting the luminescence of tryptophan at 77 K.

The effects of solvent polarity, heavy atoms and sulphur-containing compounds on the fluorescence and phosphorescence of indole and tryptophan have been investigated. The low-temperature luminescence of a group of dipeptides containing tryptophan is also reported. The phosphorescence to fluorescence quantum yield ratio and the phosphorescence lifetime are shown to be particularly sensitive to environmental factors. The relevance of these results to the interpretation of protein luminescence spectra is briefly discussed.

Dipeptides↗
PubMed1976

Humoral immunity in experimental syphilis. I. The demonstration of resistance conferred by passive immunization.

Evidence of a role for human factor(s) in immunity to experimental syphilis has been provided by the demonstration that passive immunization of rabbits by daily i.v. injections of immune serum significantly delays the appearance and markedly diminishes the severity and duration of lesions which develop after challenge with Treponema pallidum. Five rabbits were injected daily over 37 days with 3 ml/kg body weight of pooled immune rabbit serum injection with 1.1 X 10(3) T. pallidum, Nichols strain, at each of four sites. The animals developed atypical lesions of short duration after an average delay in onset of 28 days short duration after an average delay in onset of 28 days beyond the development of typical lesions in control animals similarly injected with nonimmune serum or saline. The failure of passive immunization to provide complete protection was evident not only in the development of the atypical lesions, but also in the demonstration of disseminated infection in the tissues of three of the four surviving animals 7 months after challenge. The possibility that incomplete protection may have been due to 1) insufficient immune serum levels, 2) intracellular location of T. pallidum, and/or 3) cell-mediated mechanisms is discussed.

Animals↗
PubMed1976

Humoral immunity in experimental syphilis. II. The relationship of neutralizing factors in immune serum to acquired resistance.

Evidence for a humoral mechanism in immunity to experimental syphilis was provided by the demonstration of immune rabbit serum factor(s) capable of inactivating virulent Treponema pallidum, Nichols strain, in an in vitro-in vivo neutralization test. After intratesticular infection, rabbits were bled periodically and their resistance to reinfection was determined by challenge with T. pallidum. The results of challenge showed that resistance to reinfection begins to develop by 11 days after infection, becomes complete by 3 months, and persists for at least 2 years. In the neutralization test, a mixture of treponemal suspension and serum from the infected animals was incubated anaerobically at 34 degrees C and the virulence of the treponemes was determined by intradermal inoculation into normal rabbits. Complete inactivation of treponemes by immune serum required heat-stable and heat-labile (56 degrees C, 30 min) serum components and 16 hr of incubation, and was accelerated by pre-incubation of the treponemes for 4 hr with nonimmune serum but not by 100 mug/ml of added lysozyme. Serum-neutralizing activity, first demonstrable 1 month postinfection, was quantitated by a neutralizing endpoint (NEP). A relatively close quantitative correlation was shown between the development of resistance to symptomatic reinfection and the appearance and persistence of both TPI antibody and neutralizing serum factor(s). The nature of the serum factor(s), the mechanism of treponemal inactivation, and the application of the test in assessing the immune status are discussed.

Animals↗
PubMed1975

The luminescence properties of concanavalin A.

1. The luminescence properties of native concanavalin A, both at room temperature and at 77 degrees K, are similar to those of other proteins containing tyrosine and tryptophan. 2. Binding of methyl alpha-D-glucopyranoside to concanavalin A causes a slight reduction of its fluorescence at room temperature. 3. Removal of Mn2+ and Ca2+ ions from concanavalin A causes a small increase in its fluoresence. The fluorescence: phosphorescence ratio and phosphorescence lifetime of apo-concanavalin A are similar to those of tryptophan. 4. Denaturation of concanavalin A by urea and by guanidine hydrochloride apparently takes place in two stages. Apo-concanavalin A is more easily denatured than the native molecule, but concavalin A combined with methyl alpha-D-glucopyranoside is more resistant to denaturation. 5. The luminescence properties of concanavalin A are pH-dependent. 6. The results have been interpreted in terms of the known structure and properties of concanavalin A.

Apoproteins↗
PubMed1975

The low-temperature luminescence properties of bovine alpha-lactalbumin.

The luminescence of bovine alpha-lactalbumin at 77 K has been studied and compared with that of lysozyme. Alpha-Lactalbumin has several unusual properties, including a fluorescence spectrum showing vibrational fine structure, an abnormal phosphorescence spectrum, a high fluorescence: phosphorescence ratio and an abnormal phosphorescence decay. These properties are largely due to the proximity of tryptophan residues to disulphide bonds. Reduction of all these bonds causes considerable changes in alpha-lactalbumin luminescence, as does denaturation in acid solution. Reduction of a single labile disulphide bond has little effect, and the properties of alpha-lactalbumin III, a variant lacking one disulphide bond and one trypotophan residue, are similar to those of the normal protein. Several differences between alpha-lactalbumin and lysozyme are reported. The results support the suggestion that the two tryptophan residues found in the active site cleft of alpha-lactalbumin may be largely responsible for its luminescence.

Animals↗