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Biomedical subjects

N G Miller

Publications and source records attributed to N G Miller.

At least 37 records · Page 2Linked to original sources
PubMed1992

A chromosome 1-specific DNA library from the domestic pig (Sus scrofa domestica).

Chromosomes were prepared from lymphocytes of a male domestic pig and flow-sorted on a dual-laser FACS. Twenty spots were observed, corresponding to the known pig karyotype of 18 pairs of autosomes plus the X and Y. DNA was isolated from 10,000 copies of the presumed chromosome 1 spot, restricted with Sau3A, ligated into the vector pGEM4z, and PCR amplified using universal primers; the products were then re-ligated into pUC18. After transformation into Escherichia coli, 210,000 independent colonies were obtained, 5% of which contained only vector DNA. The average insert size of the library was 405 bp. Southern blotting revealed that 36% of the clones contained single-copy DNA and that the remainder contained moderately or highly repetitive DNA. Screening with a (CA)n probe revealed that roughly 1% of the clones contained microsatellite sequences. A bulk insert of the library was biotinylated by PCR and used as a probe for chromosomal in situ suppression hybridization to pig chromosomes, which confirmed that the library is specific for chromosome 1. However, sequences from the centromeric and telomeric regions seem to be underrepresented in the library.

Animals↗
PubMed1992

Behaviour of ejaculated spermatozoa from bull, boar and ram during thin-layer countercurrent partition in aqueous two-phase systems.

Ejaculated spermatozoa from bulls, boars and rams were subjected to thin-layer countercurrent partition in aqueous two-phase systems composed of dextran T500 and polyethylene glycol 6000 (PEG) in sucrose-based Hepes-buffered media. In the basal system, the great majority of spermatozoa tended to partition with the dextran-rich bottom phase; however, by including very low levels of phosphate, they could be made to partition increasingly with the PEG-rich top phase (complete at 10 mM phosphate). A procedure was developed for carrying out four separations simultaneously under identical conditions, whereby it could be shown that distribution varied with the number of spermatozoa in the sample. In the case of bull, the effect of cell number could be reduced considerably by inclusion of small quantities of seminal plasma in the phase system, but no such effect was found for ram or boar. Considerable variation in distribution pattern was seen between samples, which did not appear to be due to technical inconsistency. Livability in the phase systems was also variable, and we believe that PEG may exert a detergent-like effect on the sperm surface that is exacerbated in highly defined media free of protective proteins.

Animals↗
PubMed1988

Protection of mice against the lethal effect of an intraperitoneal infection with Haemophilus (Actinobacillus) pleuropneumoniae after vaccination with capsular proteins.

Haemophilus (Actinobacillus) pleuropneumoniae Serotypes 5 and 7 capsular antigens (CA-1) were precipitated from culture supernatants with N-cetyl-N,N,N,-trimethylammonium bromide (Cetavlon). CA-1 contained a carbohydrate to protein ratio of 2:1 for Serotype 5 and 3:1 for Serotype 7. Glucosamine and uronic acid were detected in CA-1 from both serotypes suggesting that the capsule contained hyaluronic acid. All mice immunized intraperitoneally with CA-1 vaccine were protected from death when challenged with 10X the LD50 of the homologous but not the heterologous serotype. Oil adjuvants and the use of young (6 h) cultures were necessary for CA-1 vaccines to be protective. Deproteinization of CA-1 with chloroform and butanol followed by pronase treatment resulted in failure to protect mice from death. The protective capsular protein antigen in CA-1 vaccine may not originate from the outer membrane (OM) since repeated washing of the OM to elute the capsular protein antigen rendered the OM vaccine completely nonprotective for mice. Vaccines prepared from cell-wall lipopolysaccharide also were nonprotective for mice. Passive immunization of mice with anti-CA-1 antibody produced in rabbits to Serotype 5 was highly protective (P less than 0.01) for mice when challenged with 10X the LD50 of the homologous serotype.

Animals↗
PubMed1988

Randomized trial of artificial surfactant (ALEC) given at birth to babies from 23 to 34 weeks gestation.

Artificial surfactant (ALEC) composed of dipalmitoylphosphatidylcholine and unsaturated phosphatidylglycerol in a ratio of 7:3 (w/w) and a dose of 50-100 mg was suspended in 1 ml of cold saline and used at birth as a prophylaxis against the respiratory distress syndrome and its complications in a two centre randomized prospective trial involving 341 babies from 23 to 34 weeks gestation regardless of their antenatal problems. The surfactant had little effect in babies above 29 weeks gestation and was most beneficial in babies under 30 weeks gestation (67 controls and 69 surfactant treated babies). In this subgroup the artificial surfactant significantly reduced the inspired oxygen and peak ventilator pressure requirements during the first 96 h, the incidence of intraventricular haemorrhages from 40% to 19% (P less than 0.01), the overall mortality from 36% to 17% (P less than 0.02), the mortality due to RDS from 31% to 9% (P less than 0.01), the need for more than 28 days oxygen from 37% to 21% (P = 0.05) and the use of pancuronium in ventilated babies from 52% to 27% (P less than 0.01). There were no apparent side effects. This protein free, artificial surfactant should be a useful addition to the therapy of babies under 30 weeks gestation to reduce the severity of their RDS and the incidence of serious complications.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1988

Variation in the hemolytic activity of Leptospira interrogans serovar canicola.

Leptospira interrogans serovar canicola strain moulton was grown to a high cell density in a protein-free medium with hemin. The hemolysin produced in this culture system showed a greatly expanded spectrum of hemolysis as compared to previous reports of leptospiral hemolysin produced in a more traditional culture system containing serum.

Animals↗
PubMed1987

Cytopathology of opportunistic infection in bronchoalveolar lavage.

Bronchoalveolar lavage is an important tool for the cytologic and microbiologic examination of the lung. Silver- or Papanicolaou-stained slides from 604 lavage specimens from 344 patients were evaluated for the presence of fungal, parasitic, and viral organisms. Yeast, pseudohyphae, or hyphae occurred in 155 specimens (25.7%). Candida was the most frequent opportunistic fungus in immunosuppressed hosts. Patients with clinically significant Candida infection had many budding yeasts and pseudohyphae on cytologic preparations of their lavage fluid. Aspergillus, which occurred in five patients, was readily identified by cytologic examination and by fungal culture. Pneumocystis carinii was found in 14 patients (4%). Cytopathologic characteristics of Herpes simplex or cytomegalovirus were present in four patients (1.2%). In 414 specimens no pathogens were identified by either microbial culture or cytologic examination; usually, these patients had pulmonary hemorrhage, recurrent neoplasia, or therapy-induced lung disease to account for their abnormal chest x-rays. Cytologic and microbiologic examination of lavage fluid readily identified opportunistic pathogens. The ease and low morbidity of bronchoalveolar lavage support its use in the assessment of pulmonary infiltrates in immunocompromised hosts.

Adult↗
PubMed1984

IgG pair formation on one antigenic molecule is the main mechanism of synergy between antibodies in complement-mediated lysis.

Two rat IgG2b monoclonal antibodies bound to different epitopes on a offgle RT1Aa antigen molecule synergize in their induction of complement-mediated lysis of the red cells. The mechanism of this synergistic action has been investigated by determining the C1q:IgG relationship on red cells using the fluorescence-activated cell sorter and making use of the considerable variation in antigen density between individual red cells. With a synergistic pair of antibodies, the C1q:IgG ratio was approximately 1 and independent of antibody density per cell, indicating that the antibody molecules are present as closely associated pairs, each pair binding two C1q molecules and thus forming a cyclic tetramer. When one of the antibodies was used alone, the number of C1q molecules bound relative to the amount of antibody was higher than expected from theoretical considerations based on a presumed random distribution of antigen-antibody complex. This result can be explained if there is some mobility of the complex within the membrane. The interpretation of the results gives strong support to the hypothesis that C1q must bind bivalently to rat IgG2b complexes.

Animals↗
PubMed1984

Onychomycosis caused by Trichosporon beigelii in the United States.

We present the first case report of onychomycosis in the United States caused by Trichosporon beigelii in a normal, healthy man. The fungus, which was demonstrated histologically in the nails, was isolated on three different occasions with multiple cultures obtained each time.

Hand Dermatoses↗
PubMed1983

Tinea Pedis caused by Trichophyton violaceum.

This, to authors' knowledge, is the first report in the United States of Tinea pedis caused by Trichophyton violaceum in a recent Southeast Asian immigrant. Because of the recent entry into this country of refugees from an area of the world where T. violaceum is endemic, this anthropophilic dermatophyte may become a significant cause of dermatophytosis in the United States.

Adolescent↗
PubMed1983

Effect of ketoconazole and amphotericin B on encapsulated and non-encapsulated strains of Cryptococcus neoformans.

Growth inhibition studies were done on an encapsulated and non-encapsulated strain of Cryptococcus neoformans at the minimal inhibitory concentration and one-half the minimal inhibitory concentration of ketoconazole and amphotericin B alone and in combination. Growth of both strains was significantly inhibited by ketoconazole, amphotericin B, and the combined drugs at the minimal inhibitory concentration of each drug over a 5-day period. Calculation of the expected inhibition of growth for both strains with both drugs showed antagonism at 24 h followed by an additive effect and synergy for the remaining 4 days of the assay. Although similar results were obtained for both strains with one-half the minimal inhibitory concentration, an additive effect was observed with the drug combination at 24 h for the encapsulated strain, and an antagonistic effect was observed with the non-encapsulated strain.

Amphotericin B↗
PubMed1980

Fusion of liposome membranes by the n-alkyl bromides.

It has been found that the n-alkyl bromides are capable of inducing the fusion of unilamellar liposomes. These compounds can bring about fusion of liposomes composed of either pure phosphatidylcholine or phosphatidycholine+phosphatidic acid. Fusion of unilamellar liposomes gives rise to multilamellar structures, the morphology of which has been examined by negative staining and freeze-fracture techniques. It has been shown by microelectrophoresis that the n-alkyl bromides have no effect on the surface charge of liposomes, and fusion has been further characterized by use of light scattering and differential scanning calorimetry, the latter indicating that true mixing of the fatty acyl chains occurs upon fusion. Finally, fusion occurs at n-alkyl bromide levels below that required to saturate the aqueous phase of the system.

Calorimetry, Differential Scanning↗