Search PubMed⌕ Search

Biomedical subjects

L M Parsons

Publications and source records attributed to L M Parsons.

At least 55 records · Page 3Linked to original sources
PubMed1992

IgG subclass responses in brain and serum in Semliki Forest virus demyelinating encephalitis.

The response of IgG subclasses within the central nervous system (CNS) of the mouse to Semliki Forest virus (SFV), an alphavirus associated with meningoencephalitis and primary immune mediated demyelination, has been measured using immunocytochemistry. The subclass response in serum has been assessed using virus specific enzyme linked immunosorbent assays. In the CNS IgG1 was poorly represented throughout the sampling period of 28 days with a maximum of 3% of the total number of positive cells on day 21 after infection. Of the few IgG positive cells present on day 6, 2a and 3 positive cells were dominant. From day 9 onwards the numbers of 2b positive cells rose and by day 28 IgG2a, 2b and 3 subclasses showed roughly equal percentages of total cells counted. By contrast, in serum, anti-SFV IgG 2a and 2b were the first to appear and were dominant on day 12 and 21. Levels of anti-SFV IgG1 did not rise until after day 12 but rose steeply thereafter. IgG3 was weakly positive at days 9 and 12, rising slightly on day 21. Clearly there are differences in the patterns of subclass response between the CNS and the periphery. This may be important in the context of neurotropic viral infection.

Animals↗
PubMed1992

Molecular analysis of the Haemophilus ducreyi groE heat shock operon.

Chancroid is a sexually transmitted genital ulcer disease caused by Haemophilus ducreyi. Previously, we developed diagnostic DNA probes for H. ducreyi (L. M. Parsons, M. Shayegani, A. L. Waring, and L. H. Bopp, J. Clin. Microbiol. 27:1441-1445, 1989). In the present study, DNA sequencing of one of the diagnostic probes revealed two adjacent open reading frames (ORFs). These H. ducreyi ORFs and the encoded proteins show significant homology with the groE genes and GroES and GroEL heat shock proteins from several bacterial pathogens and with conserved eukaryotic 60-kDa heat shock proteins. The first H. ducreyi ORF (groES) is preceded by sequences similar to those of the Escherichia coli consensus heat shock promoters and is 288 nucleotides long and is capable of encoding a protein of 10.3 kDa. The second ORF (groEL) is 1,641 nucleotides long and is capable of encoding a protein of 57.8 kDa. Northern (RNA blot) analysis demonstrated the presence of a high level of groE mRNA in exponential-phase H. ducreyi grown in hemin broth at the organism's optimal growth temperature (33 degrees C), with increased levels seen following heat shock. Heat shock also increased the thermostability of the organisms, since stressed cells were more resistant to the lethal effects of rapid chilling. Electrophoretic analysis and immunoblots demonstrated that the predominant protein produced by exponential-phase H. ducreyi was a heat-inducible, immunoreactive protein of approximately 60 kDa (GroEL). Also, H. ducreyi groE mRNA and GroEL were expressed and inducible by heat in E. coli. This is the first report describing the cloning, sequencing, and expression of H. ducreyi protein-encoding genes.

Amino Acid Sequence↗
PubMed1991

Molecular relatedness of Staphylococcus epidermidis isolates obtained during a platelet transfusion-associated episode of sepsis.

Staphylococcus epidermidis was isolated from the blood of a 25-year-old pregnant woman following the administration of eight units of platelets. She had developed chills and a fever of 41.4 degrees C soon after the transfusions were completed. S. epidermidis was also obtained from all eight platelet units, as well as from the packed-erythrocyte unit associated with the first unit of platelets. The isolation of the same organism from these epidemiologically related sources provided us with the opportunity to phenotypically and genetically characterize the isolates. Several typing methods, including four molecular techniques, were used to increase our chances of finding any differences between the isolates under investigation. Phenotypic analyses demonstrated that S. epidermidis isolates from the patient, platelet units, and erythrocyte unit reacted in exactly the same manner in 15 biochemical tests, exhibited slime production, and had the same antibiotic susceptibility pattern. Genetic analyses, which included plasmid profiles, plasmid cross-hybridization, field inversion gel electrophoresis, and ribotyping, substantiated the relationships between the S. epidermidis isolates from the patient, platelet units, and erythrocyte unit. Eight S. epidermidis control strains unrelated to the case were found to differ significantly from the platelet-related strain.

Adult↗
PubMed1989

DNA probes for the identification of Haemophilus ducreyi.

Haemophilus ducreyi ATCC 33922, a virulent, well-characterized strain, was used to construct a genomic library in a bacteriophage expression vector. Three DNA fragments were selected for use as probes on the basis of their ability to encode H. ducreyi-specific proteins, as demonstrated by reactivity with rabbit polyclonal antiserum. With DNA-DNA hybridization, the three probes, labeled with 32P, reacted strongly with 16 strains of H. ducreyi obtained from a variety of sources. Thirty-seven other bacterial isolates, representing 33 different species and including organisms likely to be encountered in the urogenital tract, were also tested with the three probes. Twenty-eight of these isolates, including the genital pathogen Neisseria gonorrhoeae, showed no hybridization with the probes. In addition, herpes simplex virus-infected tissue culture cells and Treponema pallidum-infected rabbit testicular fluid were also completely nonreactive. Nine isolates, six belonging to other Haemophilus species and three belonging to Pasteurella species, reacted weakly with the probes when approximately 3.0 x 10(7) to 6.0 x 10(7) CFU was tested. When 10(5) to 10(6) CFU of these organisms was tested, the weak reactions could no longer be seen. Yet this number of H. ducreyi still reacted strongly. In fact, the three probes consistently detected 10(4) CFU of H. ducreyi in pure and mixed cultures and even produced a weak signal when only 10(3) CFU was present. It is clear from our results that use of these probes will greatly facilitate the laboratory diagnosis of this genital pathogen.

Animals↗
PubMed1989

Mirror reversal by blind subjects in cutaneous perception and motor production of letters and numbers.

A letter drawn on the forehead is often perceived as its mirror reversal. Similarly, people produce mirror reversals when asked to write a letter on the underside of a table at which they are sitting. We varied the orientation and position of the stimulated or inscribed surface, and found several examples of these two mirror-reversal phenomena in blind subjects (who had no, or very little, visual experience), as well as in sighted subjects. Furthermore, the mirror-reversal rate of the two groups of subjects as a function of orientation and position of the surface was highly correlated. Thus, the mirror-reversal phenomena should be attributed to a nonvisual, spatial cognitive scheme that is perhaps shared by sighted and blind subjects.

Adult↗
PubMed1989

Identification of immunoglobulin-containing cells in the central nervous system of the mouse following infection with the demyelinating strain of Semliki Forest virus.

Cells within the central nervous system were identified as containing immunoglobulin G, A and M using immunocytochemistry in mice previously infected with Semliki Forest virus, a togavirus causing primary immune-mediated demyelination. Cells positive for these immunoglobulins were counted in cerebellar white matter, parenchyma, meninges and choroid plexus/ventricles. No positively staining cells were seen on day 6 after infection although other inflammatory cells were present at this time and virus-specific immunoglobulin was found in serum. Cells positive for IgG appeared in all areas by day 9 and remained dominant in numbers throughout. IgM-secreting cells appeared in small numbers in the parenchyma first on day 9 and subsequently in other areas, their numbers rising to a maximum on day 12 in all areas and falling thereafter. The number of IgA-secreting cells was small. They appeared by PID 12 and continued to rise on successive sampling days. Initially IgG-positive cells were seen in the perivascular cuffs but by day 12 a few had moved away from the cuffs into the adjacent parenchyma. IgG-positive cells were seen both in and away from cuffs within areas of demyelination. IgM and IgA-positive cells tended to follow the distribution of IgG-positive cells, but in fewer numbers.

Animals↗
PubMed1987

Perceived spatial organization of cutaneous patterns on surfaces of the human body in various positions.

The perceived spatial organization of cutaneous patterns was examined in three experiments. People identified letters or numbers traced on surfaces of their body when the relative spatial orientations and positions of the body surfaces and of the stimuli were varied. Stimuli on the front or back of the head were perceived with respect to a frame of reference positioned behind those surfaces, independent of the surfaces' position and orientation. This independence may relate to the way in which the sensory apparatus on the front of the head is used in planning action. Stimuli on other surfaces of the head and body were perceived in relation to the position and orientation of the surface with respect to the whole body or trunk (most of which was usually upright). Stimuli on all transverse/horizontal surfaces were perceived with respect to frames of reference associated with the head/upper chest area. These frames were also used for stimuli on frontoparallel surfaces in front of the upper body. These observations may result from the use of "central" frames of reference that are independent of the head and are associated with the upper body. Stimuli on surfaces in other positions and orientations (with two exceptions) were perceived "externally"--that is, in frames of reference directly facing the stimulated surface. The spatial information processing we found may be fairly general because several of our main findings were also observed in very young children and blind adults and in paradigms studying perception by "active touch" and the spatial organization of the motor production of patterns.

Humans↗
PubMed1987

Imagined spatial transformation of one's body.

This study examined two related phenomena: (a) the judgment of whether a human body part belongs to the left or right half of the body and (b) the imagined spatial transformation of one's body. In three experiments, observers made left-right judgments of a part of a body whose orientation differed from their own by a rotation about one of 13 axes. To do so, they imagined themselves passing to the orientation of the stimulus. Time for (a) left-right judgments and (b) accompanying imagined spatial transformations depended on the extent of the orientation difference (OD) between the observer and stimulus. More important, time for phenomena (a) and (b) depended strongly, and in the same way, on the direction of OD. Further results showed that the rate of imagined spatial transformations can vary strongly for different axes and directions of rotation about an axis. These and other results (e.g., Parsons, 1987a) suggest that temporal and kinematic properties of imagined spatial transformations are more object-specific than could be previously assumed.

Body Image↗
PubMed1986

Yersinia enterocolitica and related species isolated from wildlife in New York State.

Fecal specimens for Yersinia screening were obtained from a variety of wild mammals, birds, reptiles, fish, and invertebrates throughout New York State. One specimen from each of 1,426 animals was examined. A total of 148 isolates of Yersinia enterocolitica and related species were obtained from 133 (9.3%) of the animals. Y. enterocolitica was isolated from 100 (7%) of the animals tested, including 81 (10%) of 812 mammals and 19 (3.3%) of 573 birds. Y. intermedia, Y. frederiksenii, and Y. kristensenii were isolated from 39 (2.7%), 5 (0.35%), and 4 (0.28%) animals, respectively. The 81 Y. enterocolitica isolates from mammals belonged to 15 serogroups and included three pathogens: two isolates of typical serogroup 0:8, the "American strain," one from a gray fox (Urocyon cinereoargenteus) and one from a porcupine (Erethizon dorsatum); and one isolate of serogroup 0:3, bacteriophage type IXb, the "Canadian strain," from a gray fox. The most prevalent serogroups recovered from mammals were 0:6,31 (16 isolates) and 0:5,27 (6 isolates). The 19 isolates of Y. enterocolitica from birds belonged to nine serogroups and included one serogroup 0:6,31 isolate from a common grackle (Quiscalus quiscula) and two serogroup 0:5,27 isolates from great horned owls (Bubo virginianus).

Animals↗
PubMed1984

A monoclonal antibody modulates the interaction of nerve growth factor with PC12 cells.

A nerve growth factor (NGF) receptor interactive monoclonal antibody (192-IgG) which enhances beta-NGF binding to PC12 cells has been produced. The hybridoma clone was obtained by fusing Sp2/0- Ag14 myeloma cells with splenocytes from Balb/C mice which had been immunized with n-octyl glucoside solubilized proteins from isolated PC12 cell plasma membranes. The antibody is an IgG, which does not bind beta-NGF. It binds to the same number of sites on PC12 cells at low temperature as does beta-NGF. The 192-IgG increases the apparent affinity of beta-NGF binding to fast receptors on PC12 cells at low temperature by a factor of 2.5- to 4-fold and enhances the photoactivatable cross-linking of beta-NGF to the same receptor while decreasing the cross-linking of beta-NGF to the slow NGF receptor. At 37 degrees C 192-IgG partially inhibits the regeneration of neurites from primed PC12 cells. The 192-IgG also reduces the rate of appearance of binding to slow NGF receptors and increases the proportion of beta-NGF bound to fast receptors at 37 degrees C. These results implicate the slow receptor as the mediator of the biological response. This antibody provides a tool for examining steps in the mechanism of action of beta-NGF after binding to the receptor.

Adrenal Gland Neoplasms↗
PubMed1983

Microbiology of a major foodborne outbreak of gastroenteritis caused by Yersinia enterocolitica serogroup O:8.

Gastrointestinal disorders of varying severity were observed in 239 (53%) of 455 campers and staff members at a coed summer camp in Sullivan County, New York, during July 1981. Five of seven hospitalized patients had appendectomies before the disease was recognized as yersiniosis. Yersinia enterocolitica serogroup O:8 (American strain) was isolated from 37 (54%) of 69 persons examined, including the head cook and 3 others of the 11-person kitchen staff. Of 48 food, water, and environmental samples collected from the camp area, Y. enterocolitica isolates belonging to the same serogroup and biogroup as the human isolates were recovered from dissolved powdered milk, a milk dispenser, and turkey chow mein. This laboratory finding supported the epidemiological data indicating a correlation between consumption of these foods and illness. Y. enterocolitica isolates of the same biogroup as the O:8 isolates but belonging to serogroup O:34 were also isolated from six campers and two samples of dissolved powdered milk. Pathogenicity studies on the Yersinia isolates were performed with three in vitro tests (calcium dependency, autoagglutination, and HeLa cell infection) and one in vivo test (intraperitoneal challenge of mice). Most of the serogroup O:8 human isolates and the chow mein isolate were positive in all four tests. Milk isolates of serogroup O:8 were positive in the in vitro tests but were relatively avirulent in mice, whereas serogroup O:34 isolates, regardless of source, were negative in all four tests.

Adolescent↗
PubMed1982

The rapid onset of tolerance to ataxic effects of ethanol in mice.

We have developed a precise quantal method for assessing the sensitivity to ethanol in the mouse. Mice placed on a clamped stationary horizontal dowel are scored ataxic or not ataxic depending on whether they are able to remain on the dowel during a 30-s observation period. A threshold blood ethanol concentration is determined by assaying tail blood drawn immediately upon recovery from ethanol-induced ataxia. This threshold is quite reproducible within a population of Swiss-Webster mice (coefficient of variation 9%). The precision of this method allowed us to follow the onset of rapid tolerance during a series of sequential IP ethanol doses. Tolerance persisted overnight in the absence of ethanol, and was found not to increase further with additional ethanol exposure on 2 subsequent days. The observed tolerance was shown not to be due to circadian changes in ethanol sensitivity or repeated practice on the task, indicating a true tissue tolerance.

Animals↗
PubMed1982

Blood brain barrier disturbance and immunoglobulin G levels in the cerebrospinal fluid of the mouse following peripheral infection with the demyelinating strain of Semliki Forest virus.

Immunoglobulin G and albumin levels have been measured in the cerebrospinal fluid and serum of Swiss A2G mice following single intraperitoneal inoculation of Semliki Forest virus. This strain of virus used causes a meningoencephalitis followed by immunologically-mediated demyelination. By the use of the levels of immunoglobulin G and albumin in cerebrospinal fluid and serum to calculate the cerebrospinal fluid: serum ratios and the cerebrospinal fluid immunoglobulin G index, it has been shown that the blood-brain barrier breakdown is mild and restricted to within the first 7-8 days after virus inoculation when the inflammatory response is maximal. Immunoglobulin G index provides a measure of synthesis of immunoglobulin G within the blood-brain barrier. Synthesis has been shown to occur from day 10 onwards up to at least day 61 following infection. Arboviruses are known to persist in central nervous system tissue and it is suggested that a continuing immune response within the central nervous system occurs and is perpetuated by persisting virus. Because of the mode of replication of Semliki Forest virus it is also possible that some of the immune response is directed against central nervous system components.

Animals↗