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C Seymour

Publications and source records attributed to C Seymour.

At least 37 records · Page 2Linked to original sources
PubMed1994

Role of elevated alpha-fetoprotein in prenatal diagnosis of junctional epidermolysis bullosa and pyloric atresia.

A case of junctional epidermolysis bullosa, Herlitz variant, and pyloric atresia in a 33 weeks' gestation male infant is reported. The second trimester amniotic fluid exhibited elevated concentrations of alpha-fetoprotein and presence of acetylcholinesterase; however, the fetus appeared anatomically normal by multiple high-resolution ultrasound examinations. This case, as well as others previously reported, shows that serious fetal skin disease should be considered as part of the differential diagnosis whenever persistent elevation of alpha-fetoprotein and presence of acetylcholinesterase are found in the amniotic fluid of a fetus that appears anatomically normal by ultrasound. Prenatal diagnosis may be established by fetal skin biopsy and extensive prenatal counseling should be offered to families on the basis of the prognosis and severity of this disease.

Acetylcholinesterase↗
PubMed1994

Phylogeny of Helicobacter isolates from bird and swine feces and description of Helicobacter pametensis sp. nov.

Previously, nine fecal isolates from wild birds and a domestic swine were identified as helicobacters by phenotypic characterization and reaction with a helicobacter genus-specific DNA probe. These isolates fell into three biotypes by analysis of phenotypic traits. To further characterize these isolates, full 16S rRNA sequences were determined for strains representing each biotype, and sequence comparison indicated that the strains represented three novel, phylogenetically defined Helicobacter species. Three 16S rRNA-based DNA probes were designed and used to identify the remaining strains. Probe reactivity divided the strains into the same three groups identified phenotypically. Six of the isolates represented a new species of the genus Helicobacter for which we propose the name Helicobacter pametensis sp. nov. The following phenotypic features distinguished H. pametensis from other Helicobacter and Campylobacter species: positive tests for oxidase, catalase, alkaline phosphatase, nitrate reduction, growth at 42 degrees C, and growth in the presence of 1% glycine; negative tests for urease, gamma glutamyl transpeptidase, indoxyl acetate hydrolysis, and hippurate hydrolysis; and susceptibility to nalidixic acid and cephalothin. H. pametensis cells were motile and possessed one subterminal sheathed flagellum at each end. The two additional Helicobacter species were similar to H. pametensis except that they were urease positive, hydrolyzed indoxyl acetate, and were resistant to cephalothin. Because these two additional species are phenotypically similar and are represented by only two isolates for one species and one isolate for the other, they are not formally named but are referred to as Helicobacter sp. "Bird-B" and Helicobacter sp. "Bird-C."(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Isolation of Helicobacter strains from wild bird and swine feces.

We report the first isolations of Helicobacter strains from wild birds and swine. Genus-specific oligonucleotide probes identified nine Cape Cod isolates from gull, tern, house sparrow, and pig feces as Helicobacter spp. and not Campylobacter spp. Antibiotic sensitivity and urease tests distinguished three phenotypes. Strains examined rapidly lost culturability under simulated natural conditions.

Animals↗
PubMed1994

Comparative virulence of blood and stool isolates of Shigella sonnei.

Shigellemia is rare in developed countries and might result from the emergence of unusually virulent strains. We compared systemic invasiveness markers of isolates from the blood of 3 temporally clustered patients with Shigella sonnei bacteremia in Boston with those of 11 unrelated contemporaneous strains from stools of people in New England. We found no difference between the two groups in O-chain length by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mouse 50% lethal dose, in vivo response to iron, and susceptibility to serum, which varied from moderately susceptible to ultrasusceptible. Mean intraperitoneal 50% lethal doses of smooth form I colonies for mice were equally low (10(5.8) CFU) in both groups, and the 50% lethal doses were lowered equally further in the two groups by predosing with iron to levels useful in mouse model sepsis studies. S. sonnei bacteremia may reflect compromised host defenses, not bacterial virulence.

Adult↗
PubMed1992

All colonies of CHO-K1 cells surviving gamma-irradiation contain non-viable cells.

This paper addresses the problem of the production of defective cells within clones arising from irradiated progenitor cells and is specifically aimed at answering the question of whether lethal mutations result from a generalised effect which lowers the ability of all the progeny to divide successfully or whether it represents a late expressed but unique lethal defect induced by radiation which occurs in some cells only and which causes those cells only to cease dividing. The results obtained from autoradiographic analysis of cells within individual surviving colonies (i.e. containing more than 150 cells) suggests that some cells in all clones are not synthesizing DNA over a 9-h period and that the proportion of non-synthesising cells rises with increasing dose of radiation from less than 3% in the controls to 80-85% after a progenitor dose of 12.5 Gy. Because of the possibility that cells had longer division times post irradiation, these results were repeated using Ki67 antibody labelling, a technique which identifies cells which are in cycle. The results were similar. This suggests the non-labelled cells were not reproducing. Both techniques were also used to look at the % labelling of morphologically abnormal cells in the colonies. The results suggested that up to 35% of these abnormal cells were actively cycling and about 20% were synthesising DNA. Abnormal cells did not appear in subcultures of survivor progeny suggesting that they may have failed to replate successfully and may contribute to the lethally mutated population. The idea that radiation induces a general instability in the cell population was supported by experiments where growth and the plating efficiency of irradiated progeny was measured daily. This revealed that the growth curves deviated from the control by a constant factor suggesting a division probability of about 70% of the control level after a progenitor dose of 10 Gy. The results are discussed in the context of their significance for survival curve analysis and for radiotherapy and radiation protection results.

Animals↗
PubMed1991

Demonstration by western blotting of antiheart antibodies before and after cardiac transplantation.

Western blotting has been used to detect antiheart antibodies in two groups of patients: two who required retransplantation for hyperacute rejection, and 22 consecutive patients, whose serum was tested at monthly intervals for three months following transplantation. Pretransplant and posttransplant serum samples were tested for IgM and IgG reactivity against the patients own heart and donor heart. In all patients the pretransplant lymphocytic crossmatch had been negative. In the two patients requiring retransplantation, both had multiple bands of strong IgM and IgG against their own heart prior to transplantation as well as antibodies against the donor heart. The study of 22 consecutive patients revealed that (1) the presence of strong antibody prior to transplantation is associated with unusually severe or frequent rejection episodes, (2) 20/22 patients made antiheart antibody following transplantation, but in 12 patients it was IgM only, and (3) most of the antiheart antibodies made posttransplant were not specific for the donor heart. Comparison of Western blotting with immunofluorescent detection of antibodies on frozen sections revealed that the Western blotting procedure is more sensitive and results are easier to interpret.

Adolescent↗
PubMed1990

Biochemical and immunological characterization of the major structural proteins of feline immunodeficiency virus.

Feline immunodeficiency virus (FIV) structural proteins were identified using sera obtained from experimentally inoculated cats. Proteins analysed by both radioimmunoprecipitation and Western blotting were specific for FIV infection and failed to cross-react with either antisera to feline leukaemia virus of feline syncytium-forming virus. Western blot analysis of purified virus revealed immunoreactive proteins with apparent Mr of 65K, 50K, 40K, 32K, 24K, 15K and 10K. The major core structural proteins of the virus were isolated by reverse phase HPLC and the aminoterminal sequences of p10 and p24 were determined. Monoclonal antibodies specific for p24 suggested the presence of a precursor protein that could be detected in 35[S]methionine/cysteine-labelled, virus-infected cell extracts. This putative precursor protein possessed an apparent Mr of 50K (Pr50gag). Further analysis revealed the presence of two additional proteins of 130K and 40K. Experiments utilizing tunicamycin, endoglycosidase H and glycopeptidase F revealed that p130 and p40 exhibited properties characteristic of glycoproteins. Our studies also indicated that FIV is immunologically related to other lentiviruses.

Amino Acid Sequence↗
PubMed1988

The effects of L-glutamate on cultured insect neurones.

The effects of L-glutamate on insect cultured neurones were studied under current and voltage-clamp conditions using conventional and whole-cell patch-clamp techniques. Brief pressure or iontophoretic application of L-glutamate produced either a depolarisation or hyperpolarisation. The current underlying the depolarisation was inwardly directed and reversed at around 0 mV while the hyperpolarisation was caused by an outward current that reversed between -60 and -80 mV. Single channel currents underlying the depolarisation were readily recorded from cell attached patches and showed multiple conductance states. Channel activity corresponding to the hyperpolarising response has not yet been observed.

Animals↗
PubMed1987

The influence of lethal mutations on the quantification of radiation transformation frequencies.

Transformation frequencies for gamma irradiated C3H 10T1/2 cells have been analysed, taking account of the occurrence of lethal mutations in these cells. Lethal mutations already noted by these authors in primary thyroid and established CHO K1 cells occur at high levels in C3H 10T1/2 cells and lead, therefore, to considerable underestimates of transformation frequency, particularly at high doses where this is expressed on a per surviving cell basis. The results may help to provide an explanation for the dose response plateau which is seen when these cells are irradiated and transformed foci per surviving cell are scored.

Animals↗
PubMed1986

Effects of intravenously infused Fluosol-DA 20% in rats.

Rats were injected with a fractionated 50 ml/kg dose of Fluosol-DA 20% with and without exposure to 100% oxygen. Animals were killed at 24, 43, 92, and 183 days post-treatment and samples taken for hematological, hepatic enzyme, histological, and perfluorochemical analyses. There were no significant differences in hemograms or hepatic enzyme findings between treatment and control groups. Differences in organ weights and histology were a result of perfluorochemical (PFC) accumulation in the tissues of treated animals. All changes were reversible. There were no effects from breathing high oxygen levels in either treatment or control animals.

Animals↗
PubMed1985

Cytomegalovirus antibody detection by three commercially available assays and complement fixation.

Four methods (complement fixation, latex agglutination, qualitative EIA, and quantitative EIA) for detecting antibody to cytomegalovirus (CMV) were compared by testing 103 sera. When ranked according to accuracy, sensitivity, and specificity, the complement fixation test was third, fourth, and first; the latex agglutination test was first, second, and third; the qualitative EIA was fourth, first, and fourth, whereas the quantitative EIA was second, third, and first, respectively. In addition, the complement fixation, latex agglutination, and quantitative EIA systems each satisfactorily detected significant antibody rises in paired sera.

Antibodies, Viral↗
PubMed1985

Long-term culture of differentiated human thyroid tissue.

Human thyroid cells obtained during surgery have been maintained in monolayer culture for at least 2 months and without loss of morphological or functional differentiation. Samples as small as 0.5 g could be cultured but best results were obtained with samples of 5-10 g. The technique used was developed in this laboratory for sheep tissue and was applicable without significant modification to human tissue. It depends on the complete absence of media changes at any time during the culture period. Energy substrates are replenished by the addition of concentrated glucose solutions to the existing media at carefully monitored intervals. Differences in both morphology and function could be observed between cultures derived from patients with different diseases, suggesting that the technique could have predictive value.

Animals↗
PubMed1984

Maintenance of differentiated sheep thyroid cells in primary culture for three months.

A method is described which permits culture of primary thyroid cells without subculture for at least 100 days. Cultures are maintained without medium changes for the entire period, and concentrated glucose is added to replenish energy supplies at carefully defined intervals. The cells retain morphological and functional differentiation shown by light and electron microscopy, PAS positive histochemistry, iodine uptake and T4 production for at least 100 days. After this time fairly sudden death of the cultures occurs. Possible mechanisms for the effect are postulated. The technique should make it possible to study long-term effects of drugs/radiation on differentiated cultures without the need for continuous subculture.

Animals↗
PubMed1983

Experimental infection of chipmunks and snowshoe hares with La Crosse and snowshoe hare viruses and four of their reassortants.

The infection of chipmunks (Tamias striatus), the vertebrate host of La Crosse (LAC) arbovirus, or snowshoe hares (Lepus americanus), the host of snowshoe hare (SSH) virus, was analyzed following subcutaneous inoculation with either LAC or SSH or certain LAC-SSH reassortant viruses. After inoculation, no adult hares or chipmunks developed signs of illness. Another reassortant, genotype LAC/LAC/SSH, has exhibited a marked inability to infect chipmunks and was avirulent for mice, probably because of a mutation in its L RNA segment. In chipmunks inoculated with reassortant viruses, neither the durations of viremias nor the maximum titers attained were demonstrably different from those found after inoculation with the parent LAC or SSH viruses. However, viruses with a SSH M RNA induced a higher viremia in snowshoe hares than viruses with a LAC M RNA. Also, the amount of virus needed to produce a detectable infection of chipmunks or hares was lower for viruses in which the M RNA came from the SSH parent than for those viruses having a LAC M RNA. Convalescent phase chipmunk and hare sera from animals infected with SSH virus or reassortant viruses having a SSH M RNA, neutralized parental SSH virus more effectively than did LAC virus. Conversely, the sera of animals infected with LAC virus or reassortants having a LAC M RNA, neutralized LAC virus more efficiently than did SSH virus.

Animals↗
PubMed1983

Viruses isolated from Panamanian sloths.

Seven virus strains were isolated in Vero cells from whole blood samples from 80 wild-caught sloths, Bradypus variegatus and Choloepus hoffmanni, from Central Panamá. Four strains of at least two different serotypes are related to Changuinola virus; two of these were associated with prolonged or recrudescent viremias. One strain is an antigenic subtype of Punta Toro virus, and another, described here as Bradypus-4 virus, is a new, antigenically ungrouped virus. A second new virus from sloths, Utive virus, forms an antigenic complex within the Simbu serogroup with Utinga and Pintupo viruses. Tests on sequential plasma samples from radio-marked free-ranging sloths and from recently captured animals maintained in captivity showed that both species develop neutralizing antibodies following naturally acquired virus infections. Antibodies against the Changuinola and Simbu serogroup viruses are widespread in both sloth species and are especially prevalent in Choloepus, but are virtually absent in all other wild vertebrate species tested.

Animals↗
PubMed1983

Experimental St. Louis encephalitis virus infection of sloths and cormorants.

Experimental infection of 11 Bradypus variegatus and Choloepus hoffmanni sloths with St. Louis encephalitis (SLE) virus produced detectable viremias of seven to 27 (median 13) days duration and maximum titers of 2.7 to 6.5 (median 5.1) log10 median suckling mouse intracranial lethal doses (SMicLD50) per ml. Experimental SLE viremia onset was delayed and maximum titer depressed in two sloths concurrently infected with naturally acquired viruses. SLE viremias in four experimentally inoculated cormorants Phalacrocorax olivaceus were shorter, and of equal or lower titer, than in sloths. Colonized Culex pipiens quinquefasciatus mosquitoes were infected by feeding on sloths circulating at least 4.8 log10 SMicLD50 of SLE virus per ml, and subsequently transmitted the infection to mice and chicks. An uninoculated baby Bradypus became infected by contact transmission from its mother. The antibody response of sloths to SLE virus was slow, being undetectable until several weeks post-inoculation. However, both sloth species developed high and long-lasting neutralizing and hemagglutination-inhibition antibody titers. The complement-fixation antibody response in Bradypus was lower and slower to develop than in Choloepus. Sloths with naturally acquired SLE virus antibody did not become detectably viremic after experimental inoculation. Neither sloths nor cormorants become overly ill from SLE virus infection.

Animals↗
PubMed1983

Serologic evidence of natural togavirus infections in Panamanian sloths and other vertebrates.

Plasmas of sloths and other Central Panamanian wild vertebrates were tested for plaque-reduction neutralizing (PRN) antibodies against four flaviviruses and one alpha-virus. Forty percent of 97 two-toed sloths, Choloepus hoffmanni, and 8% of 168 three-toed sloths, Bradypus variegatus, were specifically positive against St. Louis encephalitis (SLE) virus. The prevalence of antibody against SLE virus was considerably higher in sloths than in any other group of wild vertebrates tested, including birds, and was found mainly in adult sloths. Specific PRN antibody against yellow fever (YF) virus was found only in monkeys. A high prevalence of PRN antibody against Ilheus and Mayaro viruses was detected in agoutis, Dasyprocta punctata, and against Mayaro virus in howler monkeys, Alouatta villosa. No plasma was specifically positive against Bussuquara virus. The results are interpreted as evidence that sloths are probably not important hosts in jungle YF cycles, but may be significant amplifying hosts in tropical SLE virus cycles.

Animals↗