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Biomedical subjects

N Taylor

Publications and source records attributed to N Taylor.

At least 109 records · Page 6Linked to original sources
PubMed1988

Tubulin messenger RNA: in situ hybridization reveals bilateral increases in hypoglossal and facial nuclei following nerve transection.

We have examined the levels of mRNA coding for tubulin in cranial nerve motor nuclei following axotomy using in situ hybridization histochemistry. Following division of their peripheral axons, the neurons in the facial and hypoglossal nuclei show increased levels of tubulin mRNA both ipsilateral and contralateral to the lesion. Tubulin in situ hybridization histochemistry provides a sensitive technique to monitor dynamics of neuronal regrowth or sprouting in the peripheral and possibly the central nervous system.

Animals↗
PubMed1988

Genome rearrangements activate the Epstein-Barr virus gene whose product disrupts latency.

A defective Epstein-Barr virus (EBV) containing a deleted and rearranged genome (het DNA) causes latent EBV to replicate. This activity maps to the 2.7-kilobase-pair WZhet fragment. The BZLF1 open reading frame, present within WZhet as well as in the standard viral BamHI Z fragment, encodes the protein ZEBRA, which induces viral replication. Using gene transfers into Burkitt lymphoma cells, we now demonstrate that rearranged sequences juxtaposed to BZLF1 in het DNA facilitate expression of ZEBRA protein. Two stretches of EBV sequences within a palindromic region of het DNA contain positive regulatory elements. One set, derived from the viral large internal repeat, is newly positioned upstream of BZLF1; the second set is downstream of BZLF1 in het DNA. The capacity of defective HR-1 viruses to disrupt latency of the standard EBV genome is due to abnormal regulation of the BZLF1 gene as a result of genomic rearrangements.

Base Sequence↗
PubMed1988

Inappropriate ACTH concentrations in two patients with functioning adrenocortical carcinoma.

Two female patients with functioning adrenocortical carcinomas had plasma ACTH detectable by RIA at presentation. In both patients there was evidence for biological activity of ACTH. There was no evidence for an ectopic source of ACTH, nor for a pituitary tumour. Urinary steroid analysis showed patterns of multiple hormone secretion characteristic of adrenocortical carcinomas. The finding of detectable ACTH concentrations in a patient with Cushing's syndrome does not exclude the presence of an adrenocortical tumour.

Adrenal Gland Neoplasms↗
PubMed1988

Role of the 25-, 27-, and 29-kilodalton flagellins in Caulobacter crescentus cell motility: method for construction of deletion and Tn5 insertion mutants by gene replacement.

Caulobacter crescentus incorporates two distinct, but related proteins into the polar flagellar filament: a 27-kilodalton (kDa) flagellin is assembled proximal to the hook and a 25-kDa flagellin forms the distal end of the filament. These two proteins and a third, related flagellin protein of 29 kDa are encoded by three tandem genes (alpha-flagellin cluster) in the flaEY gene cluster (S.A. Minnich and A. Newton, Proc. Natl. Acad. Sci. USA 84: 1142-1146, 1987). Since point mutations in flagellin genes had not been isolated their requirement for flagellum function and fla gene expression was not known. To address these questions, we developed a gene replacement protocol that uses cloned flagellin genes mutagenized by either Tn5 transposons in vivo or the replacement of specific DNA fragments in vitro by the antibiotic resistance omega cassette. Analysis of gene replacement mutants constructed by this procedure led to several conclusions. (i) Mutations in any of the three flagellin genes do not cause complete loss of motility. (ii) Tn5 insertions in the 27-kDa flagellin gene and a deletion mutant of this gene do not synthesize the 27-kDa flagellin, but they do synthesize wild-type levels of the 25-kDa flagellin, which implies that the 27-kDa flagellin is not required for expression and assembly of the 25-kDa flagellin; these mutants show slightly impaired motility on swarm plates. (iii) Mutant PC7810, which is deleted for the three flagellin genes in the flaEY cluster, does not synthesize the 27- or 29-kDa flagellin, and it is significantly more impaired for motility on swarm plates than mutants with defects in only the 27-kDa flagellin gene. The synthesis of essentially normal levels of 25-kDa flagellin by strain PC7810 confirms that additional copies of the 25-kDa flagellin map outside the flaEY cluster (beta-flagellin cluster) and that these flagellin genes are active. Thus, while the 29- and 27-kDa flagellins are not absolutely essential for motility in C. crescentus, their assembly into the flagellar structure is necessary for normal flagellar function.

Bacterial Proteins↗
PubMed1988

Responses of human B-cells to recombinant lymphokines.

The effects of recombinant or purified cytokines on the growth and differentiation of human B-cells from a variety of sources were evaluated. The results suggest that IL-1, BCGF and BSF-2 have either "growth-factor" or "differentiation-factor" activity and that only IL-2 has both these functions. In addition, evidence is presented that the two forms of human IL-1 affect B-cell growth differently. Finally, the separation of human normal and leukaemic B-cells into subsets defined by their buoyant cell density, is described.

B-Lymphocytes↗
PubMed1987

Maturation signals for human B cells. Use of the MTT assay and EBV-transformed cell lines to define signals which promote cell growth or immunoglobulin secretion.

There are now several relatively well-defined signals that promote B-cell growth and maturation, usually termed 'growth' and 'differentiation' factors (e.g., IL-1, IL-2, BCGF, BSF-1 (IL-4) and BSF-2). In addition, much work has been carried out using continuous cell lines to examine the effects of these two classes of material. Using two different assays to enumerate cell growth and the ELISA to quantify Ig secretion, we would like to emphasize the importance of determining the final cell number when investigating so-called 'differentiation factors', particularly when continuous cell lines are the targets. The results presented here show that materials which promote DNA synthesis in B-cell lines (e.g., IL-1, BCGF) will also cause an increase in Ig secreted, suggesting that they can also promote Ig synthesis. However, when we used the MTT assay to quantitate cell numbers at the end of the assay and then calculated the Ig secreted per cell, only BSF-2 caused an increase in Ig secreted per cell. These results illustrate the importance of determining the final cell number when using continuous cell lines to investigate the actions of materials which modulate human B cell function and suggest that the MTT assay is a simple way of doing this.

Antibody-Producing Cells↗
PubMed1987

Separate but complementary roles for the two forms of interleukin 1 in the growth of transformed human B lymphoblasts.

Epstein-Barr virus (EBV)-transformed human B cells were seeded at densities below their capacity for autostimulatory growth and the effects of interleukin 1-alpha (IL-1-alpha), interleukin 1-beta (IL-1-beta) and B-cell growth factor (BCGF) were studied. When added separately, IL-1-alpha was able to support the growth of EBV-transformed B cells, as was BCGF. In contrast, IL-1-beta was unable to support the growth of these cells but was able to synergize with IL-1-alpha to promote cell growth. Further, the actions of BCGF and IL-1-alpha were seen to be synergistic, while those of BCGF and IL-1-beta were not. The secretion of immunoglobulin was not affected by these reagents. These findings suggest separate, but complementary roles for the two forms of human IL-1 in B-cell growth.

B-Lymphocytes↗
PubMed1987

The effects of a thromboxane synthase inhibitor, a prostacyclin analog and PGE1 on the nephritis of the NZB/W F1 mouse.

One hundred NZB/W F1 female mice were studied to compare the effects of a thromboxane synthase inhibitor (TSI), a stable prostacyclin analog (iloprost) and prostaglandin E1 (PGE1) in the evolution of the nephritis. At 10 weeks of age mice were randomly assigned to cohorts of 20 to receive either no treatment, vehicle control, PGE1, iloprost or TSI. Proteinuria, mortality, systemic blood pressure, renal immune complex deposition, urinary TX B2 and 6 keto PGF1 alpha levels were measured. Mice receiving PGE1 and iloprost had a significant delay in the onset of proteinuria and reduction in mortality at 40 weeks. The TSI treatment had no apparent effect on proteinuria or mortality. The amelioration of the nephritis was not associated with an alteration in immune complex deposition in survivors at 40 weeks. Although PGE1 and iloprost lessened the age related increase in urinary TX B2, increased the urinary 6 keto PGF1 alpha levels and the ratio of 6 keto PGF1 alpha to TX B2; so did the TSI. The PGE1 treated mice did experience a marked and persistent reduction in blood pressure but this was not observed in the iloprost- or the TSI-treated mice. All drugs tested reduced the age-related increase in thromboxane B2 but only the PGE1 and iloprost had a significant effect on the evolution of the nephritis.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Campylobacter jejuni infection in the ferret: an animal model of human campylobacteriosis.

Campylobacter infection in weanling ferrets (Mustela putorius furo) was studied as an animal model for enteric campylobacteriosis in persons. The screening of fecal cultures on selective campylobacter media showed that Campylobacter jejuni/coli was not present in the normal enteric flora. Intragastric feeding of a mixture of cat feed and 2.5 X 10(8) C jejuni isolated from ferrets with naturally occurring proliferative colitis was accomplished. All ferrets (n = 8) became infected on 3 days after they were inoculated, and at 5 to 7 days, they had bile-tinged, liquid feces with excessive mucus and blood. Ferrets gradually recovered from the diarrhea, and feces were normal 10 to 14 days after inoculation was done. Feces contained C jejuni at 14, 23, 28, 39, 46, 60, 91, 101, 109 and 144 days. In the second experiment, weanling ferrets initially were treated with 10% sodium bicarbonate, and 1 X 10(10) C jejuni organisms were administered in the cat feed. Diarrhea with fecal leukocytes and occult blood with occasional mucus appeared in almost all of the 21 ferrets from days 4 through 7. Campylobacter jejuni was isolated from the blood of 11 ferrets between 3 hours and 14 days after they were inoculated. Campylobacter jejuni bactericidal antibodies were present in serum samples at 14 days, with titers of 1:16 to 1:32. Intestinal lesions including cellular infiltration with mononuclear and polymorphonuclear leukocytes were in the lamina propria of the pyloric mucosa and small intestine of infected and control ferrets. The colon of 3 infected ferrets had small focal infiltrates of neutrophils on the lamina propria; one ferret had perivascular cuffing.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Adenovirus type 8 keratoconjunctivitis--an outbreak and its treatment with topical human fibroblast interferon.

An outbreak of keratoconjunctivitis is described which involved at least 186 people; adenovirus type 8 was identified in 50 of the cases. Topical human fibroblast interferon was assessed in a double-blind, placebo-controlled study in which 34 patients participated. Seventeen of the 34 trial patients yielded adenovirus type 8; three were infected with adenovirus type 7. The outbreak was curtailed by control of infection measures: principally careful hand-washing by medical personnel between cases and by discouraging attendance of new cases at the Eye Infirmary. Consequently the trial numbers are small. In addition there was a wide interpatient variation in the severity of infection. Therefore it was not possible to make any statistically valid conclusions concerning the recovery rate of patients receiving interferon or placebo.

Adenoviridae Infections↗
PubMed1985

Synthesis and evaluation of a prototypal artificial red cell.

A new process allows microencapsulation of purified human hemoglobin and 2,3-diphosphoglycerate to form neohemocytes. The microcapsule membrane is composed of phospholipids and cholesterol. Neohemocytes are substantially smaller than erythrocytes, contain 15.1 grams per decaliter of hemoglobin, and have a P50 value (the partial pressure of oxygen at which the hemoglobin is half-saturated) of 24.0 torr. All rats given 50-percent exchange transfusions survived with only limited evidence of reversible toxicity. Normal serum glutamate-pyruvate-transaminase values at 1, 7, and 30 days after transfusion were consistent with minimal hepatotoxicity. The concentration of blood urea-nitrogen was elevated by 35 percent after 1 day but returned to normal by day 7. However, histopathology revealed normal kidneys on day 1 as well as on days 7 and 30. Neohemocytes cleared from the circulation of transfused rats with an apparent half-life of 5.8 hours.

Alanine Transaminase↗
PubMed1984

Differential biosynthesis of proteins in separated gastric mucosal cells.

Rat gastric mucosal cells were separated according to size by rate-zonal sedimentation through a medium containing a gradient of bovine albumin. Numbers and mean sizes of cells indicated two main populations, 430-1000 microns 3 and 1500-2500 microns 3, with a discontinuity between 1000 and 1500 microns 3. Gradient fractions, combined into pools of increasing cell size, synthesized radiolabelled proteins which were resolved by electrophoresis, densitometry and computation. The smallest cells (430-800 microns 3) tended to synthesize radiolabelled proteins with the highest relative specific radioactivities. The decrease in relative specific radioactivity with increase in cell size was compatible with a progression from precursor cells towards the more differentiated state.

Animals↗
PubMed1983

Characterization of canine fetal lymphohematopoiesis: studies of CFUGM, CFUL, and CFUF.

We assayed the colony forming units for granulocyte-macrophages (CFUGM), T-lymphocytes (CFUL) and fibroblasts (CFUF) in the blood, bone marrow, liver and spleen of the canine at 45 and 55 days of gestation and 4 and 30 days post partum. As the number of CFUGM per 5 x 10(5) cells increased in the fetal liver, the number of CFUGM increased in circulating blood, whereas when the number of CFUGM decreased in liver and blood, CFUGM increased in both bone marrow and spleen. This suggests that CFUGM are produced in the liver, are released into the circulation and then transported to the spleen and bone marrow. CFUF studies showed that canine fetal bone marrow and spleen are active sites of fibroblast proliferation, whereas the liver is not. Morphologic examination of colonies derived from concanavalin-A stimulated progenitors ("CFUL") demonstrated that these colonies from fetal tissues and adult bone marrow were not exclusively lymphoid but were also made up of significant numbers of precursors of the myeloid and monocytic series. Lymphocyte stimulation tests (LST) showed the presence of a large population of mitogen-independent dividing cells, suggesting that fetal lymphohematopoiesis may be at least partially under the influence of factors other than those of adult cells.

Animals↗
PubMed1982

Short-term tests for transplacentally active carcinogens: sensitivity of the transplacental micronueleus test to diethylnitrosamine.

DEN is an established animal carcinogen, and is effective transplacentally; but like other nitrosamines, its genotoxicity is difficult to assess in established shortterm cytogenetic tests. The mouse transplacental micronucleus test demonstrates the ability of DEN to cause chromosome breakage in utero. Positive results were obtained from the 15th day of gestation and a linear dose-response relationship is expressed when micronucleated polychromatic erythrocytes are measured in neonatal blood, after transplacental exposure late in gestation. 25mg/kg (the lowest dose tested) caused a significant increase in MNPCEs (p less than 0.05). A micronucleus test based on polychromatic erythrocytes in neonatal blood permits maximal exploitation of the metabolic capacity of the prenatal liver and is therefore sensitive to clastogenic chemicals not activated by adult bone marrow.

Animals↗
PubMed1982

Familial effects on plasma sex-steroid content in man: testosterone, estradiol and Sex-hormone-binding globulin.

We investigated whether familial factors influence the plasma content of sex-steroids and sex-hormone-binding globulin (SHBG) in 98 adult males of 66 families. They had no apparent endocrine dysfunction, The 0800-1100 hr plasma levels of testosterone, 5 alpha-dihydrotestosterone (DHT), estradiol-17 beta (E2) and estrone (E1) were measured by radioimmunoassay. The free fractions of E2 and testosterone were determined by equilibrium dialysis, and binding capacity of SHBG was also calculated. The data were analyzed by analysis of variance. We observed that the differences in the plasma content of testosterone (p = .02). SHBG binding capacity (p = 0.1), and E2 (p = 0.3), free E2 index (p = .05) were all substantially less variable within groups of brothers than among non-brothers. The variability of the plasma concentration of DHT, free testosterone and E1 was not significantly less within brothers than among non-brothers. The correlation between either plasma testosterone content (r = .14) or SHBG binding capacity (r = .12) and percent of ideal body weight was not significant statistically. Age had no effect on the results. Our data suggest that genetic and/or environmental factors may affect the plasma content of testosterone, E2 and SHBG binding capacity.

Adult↗