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Biomedical subjects

E H White

Publications and source records attributed to E H White.

At least 37 records · Page 2Linked to original sources
PubMed1991

Analogs and derivatives of firefly oxyluciferin, the light emitter in firefly bioluminescence.

The 5-methyl analog of firefly oxyluciferin, two isomeric O-methyl ether derivatives of it and an O,O'-dimethyl ether derivative were synthesized and their UV absorption and fluorescence emission spectra were determined. Comparisons of the emission data with the emission wavelength in bioluminescence indicate that the mono-anions of firefly oxyluciferin are candidates for the light-emitters in bioluminescence. Further, we have found that the chemiluminescence of active esters of firefly luciferin produces (from the keto form of oxyluciferin) only red light emission under a variety of conditions; a yellow-green light emission (from the enolic forms of the oxyluciferin product) could not be elicited.

Animals↗
PubMed1991

Effects of cytochalasin D and methylamine on intracellular growth of Legionella pneumophila in amoebae and human monocyte-like cells.

A cloned and axenically cultured strain of Hartmannella vermiformis was used as a model to study intracellular multiplication of Legionella pneumophila in amoebae. The growth of L. pneumophilia in both H. vermiformis and a human monocyte-like cell line (U937) was investigated with cytoskeletal and metabolic inhibitors. L. pneumophila replicated only intracellularly in these cellular models, and electron microscopy showed ultrastructural similarities in the initial phase of multiplication. Treatment of amoebae with an inhibitor of microfilament-dependent phagocytosis (cytochalasin D, 0.5 or 1.0 micrograms/ml) did not inhibit intracellular growth of L. pneumophila; however, intracellular multiplication was inhibited by treatment of U937 monocytes with the same concentrations of cytochalasin D. Methylamine (10 to 100 mM), an inhibitor of adsorptive pinocytosis, inhibited the replication of L. pneumophila in amoebae in a dose-dependent manner. All doses of methylamine tested (10 to 50 mM) inhibited growth of L. pneumophila in U937 monocytes. Cytochalasin D and methylamine had no effect on the multiplication of L. pneumophila in culture medium or on the viability of amoebae or U937 monocytes. Intracellular replication of L. pneumophila in H. vermiformis may be accomplished by a cytochalasin D-independent mechanism, such as adsorptive pinocytosis. In contrast, both cytochalasin D- and methylamine-sensitive mechanisms may be essential for the intracellular multiplication of L. pneumophila in U937 monocytes.

Analysis of Variance↗
PubMed1990

Influence of the 60-megadalton plasmid on adherence of Escherichia coli O157:H7 and genetic derivatives.

The adherence of enterohemorrhagic Escherichia coli serotype O157:H7 and various genetic derivatives to Henle 407 intestinal and HEp-2 epithelial cell lines was examined by light and electron microscopy. The parent outbreak strain, 7785, harbors a 60-megadalton serotype-specific plasmid designated pO157 and adhered to both cell lines, as determined by light microscopy. A plasmidless derivative, 2-45, showed reduced adherence to both cell lines. After being labeled with Tn801, pO157 was transformed into E. coli C600, E. coli HB101, and E. coli GH42, and back into 2-45. Both E. coli C600 and HB101 transformants adhered weakly; full adherence was restored to the 2-45(pO157::Tn801) transformant. Transmission electron microscopy (EM) demonstrated the intimate attachment of HB101(pO157::Tn801) to Henle 407 cells which formed cuplike structures and areas of possible actin polymerization adjacent to adhering bacterial cells; scanning EM further extended these observations. EM studies of E. coli O157:H7 strains were hampered by extensive intestinal cell damage, presumably due to the action of Shiga-like toxins. EM also demonstrated that 7785 and its plasmidless derivative 2-45 were piliated and that no pili were apparent on HB101(pO157::Tn801) or GH42//(pO157::Tn801). The plasmid pO157 appears to modify the eucaryotic cell adherence of E. coli O157:H7 and to confer that adherence on E. coli HB101 through surface structures other than pili. These findings, when compared with other published reports, also suggest similarities between enterohemorrhagic and enteropathogenic E. coli adherence properties.

Bacterial Adhesion↗
PubMed1990

Monoclonal antibody recognizing a species-specific protein from Streptococcus pneumoniae.

Monoclonal antibodies (MAbs) against a nonencapsulated strain (R36A) of Streptococcus pneumoniae were produced to aid in a search for antigens common to this species. By Western immunoblot analysis, a species-specific 37-kilodalton (kDa) protein was found in lysates of 24 different encapsulated strains of S. pneumoniae. Monoclonal antibodies against the 37-kDa antigen did not react with 55 heterologous strains representing 19 genera and 36 species of bacteria that can also cause acute lower respiratory tract disease. Immunogold staining suggests that the antigen is synthesized inside the pneumococcal cell. However, MAbs to the 37-kDa antigen bound whole cells in the enzyme-linked immunosorbent assay and the indirect immunofluorescence assay. Antibody-binding epitopes of the antigen are probably exposed on the outer surface of the pneumococcus cell wall. The effectiveness of the 37-kDa antigen as a useful diagnostic marker is under study.

Antibodies, Bacterial↗
PubMed1990

Alga associated with diarrhea in patients with acquired immunodeficiency syndrome and in travelers.

Spherical bodies resembling coccidian oocysts and measuring 8.0 to 9.0 microns in diameter were seen in the stools of eight persons with explosive, watery diarrhea. Seven had recently traveled to tropical countries, mostly in the Caribbean, and four had acquired immunodeficiency syndrome. The structures were easily discernible in wet mounts by light microscopy and contained variable numbers of granular inclusions, but were refractory to, or stained partially with, 12 commonly used laboratory stains. Electron microscopy revealed an outer fibrillar coat, a thin cell wall, granules, and organelles which were not surrounded by membranes. One type of organelle was similar to the thylakoid photosynthesizing organelles of blue-green algae (cyanobacteria). These findings indicate that the bodies may be a species of blue-green algae.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Immunoelectronmicroscopic characterization of monoclonal antibodies (MAbs) against Cryptococcus neoformans.

Three monoclonal antibodies (MAbs) (BA4, BD1, CD6) reacted with Cryptococcus neoformans capsular glucuronoxylomannan (GXM) polysaccharide showing distinctive patterns against four serotypes as revealed by enzyme immunoassay (EIA), dot EIA, and immunofluorescence. Immunoelectron microscopy (IEM) was used to characterize binding sites for the MAbs on the C. neoformans capsule. All three MAbs bound to the capsule of serotype A strains 9104 and 9759. Differences in the intensity of binding to the two serotype A strains could not be explained by capsule diameter. The MAb BA-4 IgM bound well to 9759 (large capsule) and poorly to 9104 (small capsule), whereas MAb BD-1 (IgG-1) bound well to strain 9104 and poorly to strain 9759. Spurr's embedment inactivated the BA-4-binding epitopes in the C. neoformans 9759 capsule, but did not inactivate the ones that bound to BD-1. The epitopes recognized by BA-4 were different than the BD-1-binding determinants. The MAb CD-6 bound to a cytoplasmic precursor of capsular GXM. CD-6 (IgG) stained the capsule, cell wall, and cytoplasm of both C. neoformans tester strains. Competitive binding experiments were conducted. Single immunogold labelling showed that BD-1 inhibited the binding of BA-4, but not vice versa. The interaction between CD-6 and BA-4 resulted in a reciprocal inhibition. Double-labelling experiments showed reciprocal inhibition between BA-4 and each of the IgG MAbs. These MAbs are directed against capsular polysaccharide or its intracellular precursor. None of the MAbs stained C. neoformans cap 67, an acapsular mutant that does not contain GXM.

Antibodies, Fungal↗
PubMed1986

Ultrastructure of acapsular mutant Cryptococcus neoformans cap 67 and monosaccharide composition of cell extracts.

Acapsular mutant Cryptococcus neoformans cap 67 was grown in Pine's citrate broth medium for 3 days and the cells then transferred to a nitrogen-free medium for 6 days. The cells were subjected to a four stage extraction with buffered Triton-X100, cold dilute alkaline borohydride, hot dilute acetic acid, and a second alkaline extraction. Galactoxylomannan antigens were recovered from the culture supernates of both 3 day-old and 9 day-old yeast cells. The alkaline extracts contained water-soluble galactoxylomannan and a water-insoluble glucan. Dilute acid treatment released a minor amount of carbohydrate from the cells. The second alkaline extraction yielded increased amounts of glucan and galactoxylomannan from the 9 day-old cells. Soluble non-dialyzable cell extracts were antigenically identical in immunodiffusion with the culture supernate antigens. After the extraction sequence, all of the galactose, xylose, and mannose were removed from the cells. The walls retained their shape after extraction but their layers were loosened. Cells resuspended in nitrogen-free medium for six days developed thickened walls with alternating electron-dense and electron-lucent layers. The major constituent of the thickened 9 day-old cell walls was glucose, only 5% glucosamine was detected.

Antigens, Fungal↗
PubMed1985

Alkylation of amide linkages and cleavage of the C chain in the enzyme-activated-substrate inhibition of alpha-chymotrypsin with N-nitrosamides.

Active-site-directed N-nitrosamides inhibit alpha-chymotrypsin through an enzyme-activated-substrate mechanism. In this work, the activation results in the release--in the active site--of benzyl carbonium ions, which alkylate and inhibit the enzyme. The final ratio of benzyl groups to enzyme molecules is 1.0, but the alkyl groups are scattered over a number of sites. Reduction and alkylation of the inhibited enzyme generate peptides insoluble in most media. Guanidine hydrochloride at 6 M proved a good solvent, and its use as an eluant on G-75 Sephadex permitted separation of the peptides. In the case of 14C-labeled enzyme, such an approach has shown that all of the alkylation occurs on the C chain of the enzyme, the chain of which the active site is constructed. Chemical modification of the peptides with ethylenediamine and N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide rendered them soluble in dilute acid, permitting high-performance liquid chromatographic separation. Model studies have shown that the benzyl carbonium ions are highly reactive, alkylating amide linkages at both oxygen and nitrogen. Alkylation at oxygen produces imidate esters, which are labile centers. Hydrolysis of protein imidates results in a cleavage of the chain at that point, and separation of the peptides formed (followed by analysis) permits their identification. In our inhibition of alpha-chymotrypsin, a major site of O-alkylation has been identified as the carbonyl oxygen of Ser-214. Alkylation at the nitrogen atom of amide linkages generates stable labels; full hydrolysis with 6 N HC1 then leads to N-benzyl amino acids characteristic of those sites. Chromatography of this mixture and also 13C NMR spectroscopy of the intact inhibited enzyme have shown that three major N-alkylations have occurred. Tryptic digestion of the C chain of chymotrypsin, which contains all of the alkylation sites, provides evidence that the stable N sites are principally located between residue 216 and residue 230. These locations are consistent with predictions of alkylation sites based on inspection of a molecular model of chymotrypsin, with special reference to the aromatic binding pocket.

Alkylation↗
PubMed1982

Diflunisal. A new oral analgesic with an unusually long duration of action.

The analgesic efficacy of single 500- and 1,000-mg doses of diflunisal (Dolobid), a new nonsteroidal anti-inflammatory analgesic, was compared in a double-blind study with that of acetaminophen, 600 mg, the combination of acetaminophen, 600 mg, with codeine phosphate, 60 mg, and placebo in 159 oral surgery outpatients. Using a self-rating record, patients rated their pain and its relief hourly for 12 hours after medication. Both doses of diflunisal were significantly more effective than acetaminophen alone and produced peak analgesia comparable to that of the acetaminophen-codeine combination. Diflunisal proved to have an unusually long duration of analgesic action. Acetaminophen and the combination were significantly superior to placebo through hours 2 and 5, respectively; both doses of diflunisal were significantly superior through the end of the 12-hour observation period. None of the active treatments produced more side effects than the placebo.

Acetaminophen↗
PubMed1980

An evaluation of the analgesic efficacy of proquazone and aspirin in postoperative dental pain.

The analgesic efficacy of 75, 150, and 300 mg proquazone, a new nonsteroidal antiinflammatory agents, was compared to that of 650 mg aspirin and a placebo in outpatients who had moderate or severe pain following the surgical removal of impacted third molars. Estimates of the relative potency of proquazone to aspirin ranged from 4.9 to 6.2 for total analgesic effect and from 7.7 to 8.4 for peak analgesic effect. Each dosage level of proquazone and aspirin provided significant analgesia compared to placebo and was well tolerated. Adverse effects were transitory and did not appear to be dose related for proquazone.

Adolescent↗
PubMed1979

Aryl-monoalkyl and cyclic triazenes: direct-acting mutagens.

An aryl-monoalkyl triazene, methyl-p-tolyl triazene (MTT) and a cyclic triazene (delta2-triazoline) are direct-acting mutagens for Salmonella typhimurium bacteria and for cell-free Hemophilus influenzae DNA. MTT causes reversion of the hisG46 base-substitution mutation, but no reversion of the hisD3052 frameshift mutation. Induced mutation frequency is not strongly influenced by modifications in the genetic background of the S. typhimurium Ames tester strains, but is mildly enhanced by the addition of a pool of amino acids to the plating medium and is strongly enhanced by liquid preincubation before plating.

Base Sequence↗
PubMed1979

Comparison of mutagenicity, antitumor activity, and chemical properties of selected nitrosoureas and nitrosoamides.

A number of nitrosoureas and nitrosoamides have been compared with respect to mutagenicity for Salmonella typhimurium, in vitro cytotoxicity, in vivo toxicity and antitumor activity against murine L1210 leukemia, and chemical properties. Despite chemical similarities between the nitrosoureas and nitrosoamides, they show important differences in biological activity. Some of the nitrosoureas are very active antitumor agents, and they are less mutagenic than are the corresponding nitrosoamides, which lack antitumor activity.

Animals↗
PubMed1977

Giving health care to minority patients.

Health care is usually thought of as a basic right of each individual. This so-called basic right is denied to many mainly because of their economic situation and the color of their skin. There is a need for more blacks, Indians, Mexican-Americans, Puerto Ricans, and Asians in the health care field. The numbers are low and the training process slow. Time is needed to prepare ethnic people of color. Since most of the deliveries of health care are white, these white workers must become sensitive to the traditions, values and attitudes of the ethnic groups of color. Schools of nursing are beginning to include cultural differences in nursing curriculums, but the majority of the nurses who practice are not aware of and are not sensitive to the needs of nonwhite patients. Nursing must help solve problems of the ethnic groups of color. Nurses must become personally involved in the injustices of health care. As Marie Branch states, there must be "personal reeducation." When this occurs, health care to the minority client will improve.

Black or African American↗