Search PubMed⌕ Search

Biomedical subjects

R Harris

Publications and source records attributed to R Harris.

At least 289 records · Page 16Linked to original sources
PubMed1988

Ketanserin modulates rabbit foot cooling in the presence or absence of exogenous serotonin.

Since hypothermic conditions augment sensitivity to vasoactive amines like serotonin (5-HT) and 5-HT is associated with the etiology of Raynaud's phenomenon, this amine perhaps plays a role in cold-induced vasoconstriction. To determine if 5-HT participated in normal peripheral cooling and if ketanserin (KET), a 5-HT blocker, modulated such cooling, four groups of New Zealand white rabbits (N = 33) were studied. The femoral artery was cannulated to allow perfusion of a hindlimb. Thermistors were implanted in the footpad and rectum. The hindfoot was exposed to a 15 degrees C bath for 30 min, while footpad and rectal temperatures were recorded. During cold exposure, 5-HT (5 x 10(-2) M, group 1), KET (0.1 mg/kg) + 5-HT (group 2), KET (group 3), or saline (group 4) was perfused through the hindlimb. Groups 2 and 3 were also pretreated with KET (0.1 mg/kg perfused over 30 min). The rabbit footpad cooled rapidly when exposed to exogenous 5-HT (group 1). KET treatment in the presence of exogenous 5-HT (group 2) was associated with a significantly (P less than 0.05) reduced cooling rate. KET treatment in the absence of exogenous 5-HT (group 3) was also associated with a significantly (P less than 0.05) elevated limb temperature when compared to controls (group 4). This suggested that endogenous 5-HT participated in limb cooling. Therefore, as noted for Raynaud's disease, 5-HT may also influence peripheral cooling of tissues free of such pathologies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Laboratory diagnosis of Mycoplasma pneumoniae infection. 2. Comparison of methods for the direct detection of specific antigen or nucleic acid sequences in respiratory exudates.

The efficiency of the direct detection of Mycoplasma pneumoniae in respiratory exudates by an antigen capture, indirect enzyme immunoassay (Ag-EIA), has been compared with its detection with a cDNA probe ('Gen-Probe assay') directed against the specific ribosomal RNA sequences of the organism ('Mycoplasma pneumoniae Rapid Diagnostic System', Gen-Probe, San Diego, California). Both assays showed excellent specificity against a range of mycoplasma species suspended in negative nasopharyngeal aspirates; only M. pneumoniae and M. genitalium reacted. In experiments with graded doses of viable M. pneumoniae cells suspended in negative nasopharyngeal aspirate, the Gen-Probe assay was more sensitive than Ag-EIA; detection limits were respectively 2 X 10(3) c.f.u./ml (3.2 X 10(5) genomes) and 2.5 X 10(4) c.f.u./ml (4 X 10(6) genomes); detection levels 10-100 times less sensitive than culture. The two assays were also tested on nasopharyngeal aspirates or sputum specimens from 90 patients with respiratory infection; 67 of these were culture- or seronegative for M. pneumoniae and 23 were culture- or seropositive. Ag-EIA detected 21 (91%) of the latter but the Gen-Probe assay detected only 5 (22%). Both assays were negative with the 67 culture-/sero-negatives; there were no Gen-Probe assay positive/Ag-EIA negatives. Overall, it is concluded that although Ag-EIA and the Gen-Probe assay are effective substitutes for culture as a diagnostic procedure, there is a significant problem with samples which are culture-negative and from patients who have good serological evidence of current infection. Possible reasons for the disparity between the two assays are advanced.

Antigens, Bacterial↗
PubMed1988

A survey of neural tube defect pregnancies in north-west England.

The preliminary results are reported of the first eighteen months of a three year survey of NTD affected pregnancies in the North Western Region of England. The results are consistent with a general decline in the incidence of NTD. Prenatal screening has been available for 10 years but babies continue to be born with NTD. Supportive services are often lacking for parents having had an affected pregnancy and methods of imparting advice regarding recurrence risks have been shown to be variable and not always efficient.

Cross-Sectional Studies↗
PubMed1988

Distribution of extrajunctional acetylcholine receptors on a vertebrate muscle: evaluated by using a scanning electron microscope autoradiographic procedure.

A scanning electron microscope (SEM) autoradiographic technique was calibrated and used to determine the site density of acetylcholine receptors within 250 micron of the neuromuscular junction in innervated as well as 3- and 10-d denervated sternomastoid muscle of the mouse. In all these groups sharp gradients of receptor site density are seen around the endplates in the first 2-7 micron, continuing less sharply to between 25 and 50 micron. Beyond 50 micron (to 250 micron) a spatial density gradient is present 3 d after denervation, but none exist by 10 d. These results suggest that the postdenervation steady-state extrajunctional receptor site density is reached sooner near the junction than away from the junction. The usefulness of SEM autoradiography to study the expression and distribution of membrane molecules at high resolution is demonstrated.

Animals↗
PubMed1988

Expression of human CD4 by two human-mouse interlineage hybrids.

Two hybrid cell lines expressing human CD4 were prepared by fusing human B-lymphoid cells with the mouse T-lymphoma BW5147. Hybrid TF42 was derived from a human B-lymphoblastoid line and TF53.1 from a human B-ALL. Variants of these hybrids expressing or lacking CD4 were isolated by sorting cells stained with the monoclonal antibody (mAb) OKT4 on a fluorescence-activated cell sorter (FACS). Cytogenetic, isoenzyme and DNA analysis confirmed the presence of human chromosome 12 in the CD4+ hybrids, and revealed that CD4 expression by TF42 was associated with multiple copies of this chromosome. Of seventy mAb recognizing human T-cell antigens screened on the CD4+ and CD4- variants of the two hybrids, only mAb recognizing CD4 and Leu 8 reacted with the CD4+ cells. These hybrids should be useful in the preparation, screening and analysis of anti-CD4 monoclonal antibodies, and in studies of CD4 epitopes recognized by HIV.

Animals↗
PubMed1988

Epitope mapping of the human immunodeficiency virus type 1 gp120 with monoclonal antibodies.

A soluble form of recombinant gp120 of human immunodeficiency virus type 1 was used as an immunogen for production of murine monoclonal antibodies. These monoclonal antibodies were characterized for their ability to block the interaction between gp120 and the acquired immunodeficiency syndrome virus receptor, CD4. Three of the monoclonal antibodies were found to inhibit this interaction, whereas the other antibodies were found to be ineffective at blocking binding. The gp120 epitopes which are recognized by these monoclonal antibodies were mapped by using a combination of Western blot (immunoblot) analysis of gp120 proteolytic fragments, immunoaffinity purification of fragments of gp120, and antibody screening of a random gp120 gene fragment expression library produced in the lambda gt11 expression system. Two monoclonal antibodies which blocked gp120-CD4 interaction were found to map to adjacent sites in the carboxy-terminal region of the glycoprotein, suggesting that this area is important in the interaction between gp120 and CD4. One nonblocking antibody was found to map to a position that was C terminal to this CD4 blocking region. Interestingly, the other nonblocking monoclonal antibodies were found to map either to a highly conserved region in the central part of the gp120 polypeptide or to a highly conserved region near the N terminus of the glycoprotein. N-terminal deletion mutants of the soluble envelope glycoprotein which lack these highly conserved domains but maintain the C-terminal CD4 interaction sites were unable to bind tightly to the CD4 receptor. These results suggest that although the N-terminal and central conserved domains of intact gp120 do not appear to be directly required for CD4 binding, they may contain information that allows other parts of the molecule to form the appropriate structure for CD4 interaction.

Animals↗
PubMed1988

An autosomal dominant multiple pterygium syndrome.

Three sibs and their mother with features of a multiple pterygium syndrome are reported. Inheritance in this family is consistent with autosomal dominant inheritance with great variation in severity between affected subjects. The importance of examining other family members closely in cases of multiple pterygium is emphasised.

Abnormalities, Multiple↗
PubMed1988

Streptococcal pharyngitis. Comparison of latex agglutination and throat culture.

Despite its imperfections, the throat culture remains the "gold standard" against which all rapid streptococcal antigen detection tests are compared. Using triple throat swabs, the accuracy of a rapid latex agglutination (LA) test and back up throat culture was determined and compared with a simultaneously obtained additional throat culture in children with suspected streptococcal pharyngitis. Although there was a 95 percent concordancy between throat cultures, the sensitivity of the throat culture was only 87 percent. Despite the LA test's lower sensitivity (78 percent), in this clinical population with a relatively low prevalence of positive throat cultures (19 percent), the predictive value of a negative LA test was only slightly lower than that of the throat culture (94-95 percent vs. 97 percent). Backup throat cultures are commonly recommended for patients with initially negative LA test results, but 10 percent of the patients with group A beta-hemolytic streptococci-positive throat cultures would have been undetected using this approach.

Adolescent↗
PubMed1988

Genetic factors in myasthenia gravis: a family study.

We studied forty-four patients with myasthenia gravis (MG) and their families. Thirty percent of patients had a confirmed family history of autoimmune disease; in one case this was MG. In all the families with autoimmune disease, the affected relatives were related to the patients through the maternal line. HLA-B8 and DR3 were increased in patients due to the high incidence of these antigens in female, nonthymoma patients with onset before 40 years. HLA-B5 was increased in patients with older onset. The haplotype A1-B8-DR3 was not found to be increased given the presence of B8 or DR3.

Adolescent↗
PubMed1988

Down's syndrome lymphoid cell lines exhibit increased adhesion due to the over-expression of lymphocyte function-associated antigen (LFA-1).

We have analysed homotypic adhesion induced by the phorbol ester TPA in EBV-immortalized Down's syndrome (trisomy 21) and normal lymphoblastoid cell lines. Our results show that the trisomy 21 cells aggregated more readily than normal cells. The aggregation of the two types of cell was blocked effectively by the addition of monoclonal antibodies to the alpha and beta chains (CD11a, CD18) of lymphocyte function-associated antigen (LFA-), but not by monoclonal antibodies to LFA-3 and the alpha chain of p150,95 (CD11c). Since TPA did not increase the expression of CD18 on trisomy 21 cells, we conclude that the increased adhesiveness is the result of over-expression of CD18 as a result of gene dosage.

Antibodies, Monoclonal↗
PubMed1988

The expression of CD18 is increased on Trisomy 21 (Down syndrome) lymphoblastoid cells.

The monoclonal antibody (MAB) 60.3 reacts with the beta chain (CD18) of lymphocyte function associated antigen (LFA-1), encoded by a gene on chromosome 21. We have used 60.3 to measure the expression of CD18 on lymphoblastoid cell-lines derived from persons with Trisomy 21 (Down syndrome) by quantitative fluorescence flow cytometric analysis. This showed that CD18 expression is increased on Trisomy 21 compared with normal cells, whereas neither HLA-class I, nor transferrin receptor expression are significantly affected. Similar results were obtained with the CD18 MAB MHM 23, and with the CD11a MAB MHM 24 (LFA-1 alpha). These results suggest that the increase in CD18 expression by Trisomy 21 cells is due to gene dosage, and could influence the immune status of persons with Down syndrome.

Antibodies, Monoclonal↗
PubMed1988

Bone marrow transplantation for poor prognosis neuroblastoma.

These studies suggest that intensive chemoradiotherapy (eg., VAMP-TBI), if given relatively soon after diagnosis and before development of progressive disease, improves long-term survival for patients with advanced neuroblastoma. Although this particular therapy is not useful for those who already have developed progressive disease, other intensive regimens may warrant testing in this latter group of patients. Our current study is testing aggressive induction chemotherapy, ex vivo purging of autologous marrow, and VAMP-TBI followed by BMT. Because of the increasing risk of progressive disease with time after diagnosis, we recommend beginning the BMT phase by 20 weeks after diagnosis. This should result in 85% of newly diagnosed patients entering the BMT phase without progressive disease; and, with fewer toxic deaths, 90% should survive the BMT phase. Thus, approximately 70% of patients could be disease-free survivors 8-9 months after diagnosis. Because a significant number of patients still develop progressive disease during induction or after BMT, efforts are being made to improve induction and pretransplant therapies and to identify prognostic factors. If modifications of the current regimens do not decrease the rate of progressive disease, it may be necessary to develop additional or different therapy for patients identified to be at high risk. Hopefully, new strategies will further increase the percentage of patients with tumor-free survival.

Bone Marrow Transplantation↗