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Biomedical subjects

D Lowe

Publications and source records attributed to D Lowe.

14 recordsLinked to original sources
PubMed1992

Detection of human leukemia inhibitory factor by monoclonal antibody based ELISA.

Leukemia inhibitory factor (LIF) is known to exhibit multiple functions by regulating the growth and differentiation of multiple normal cell types as well as malignant cells. To have a better understanding of the role of LIF, it is important to determine the level of LIF in various biological samples by developing an easy, sensitive and LIF specific assay. In this study, we have established a double monoclonal antibody (mAb) based ELISA. Four hybridoma cell lines (D3.14.1, D4.16.9, D25.1.4 and D62.3.2) secreting murine monoclonal antibodies (mAbs) against recombinant human leukemia inhibitory factor (rHuLIF) were produced by immunization of BALB/c mice with rHuLIF and by fusing immune spleen cells with P3X63Ag8U.1 myeloma cells. These mAbs each belong to the IgG1 isotype and have unique isoelectrofocusing point patterns. All four mAbs were shown to have high affinities for rHuLIF (Kd = 7 x 10(-10) to 6 x 10(-11) M) and were able to recognize the native as well as the reduced rHuLIF in an immunoblotting assay. All these mAbs showed no cross-reactivities to IL-1, IL-3, IL-6, TNF-alpha, GCSF and GMCSF. MAb D3.14.1 showed a weak binding to Oncostatin M but not to rMuLIF whereas the other three mAbs D4.16.9, D25.1.4 and D62.3.2 showed cross-reactivity to rMuLIF but not to Oncostatin M. Data obtained from a competitive binding enzyme-linked immunosorbent assay (ELISA) suggested that these four mAbs recognized different epitopes on rHuLIF. Using mAb D4.16.9 as coat antibody and horseradish peroxidase (HRP) conjugated mAb D3.14.1 as the conjugate antibody we established a double mAb based ELISA specific for human LIF which could detect as little as 100 pg/ml and 10 pg/ml of rHuLIF in the absence and in the presence of the ELAST ELISA amplification system, respectively. The addition of serum had very minimal effect on this ELISA.

Antibodies, Monoclonal↗
PubMed1992

Analysis of the rat ribosomal DNA promoter: characterization of linker-scanning mutants and of the binding of UBF.

To investigate the mechanism of transcription of the rat ribosomal DNA (rDNA) promoter, a series of 23 linker-scanning mutants were constructed and assayed in transfected CHO cells and with cell-free extracts. With minor variation, the results of the in vitro and in vivo assays paralleled one another. For example, these assays demonstrated that the mutagenesis of bases from -133 to -124, and those from -106 to -101 of the rDNA promoter significantly inhibited transcription both in vivo and in vitro. Both of these sites lie within the upstream promoter element (UPE) of the rDNA promoter. Several constructs, in particular one that mutated the bases between -49 and -45, were better promoters in vivo than the wild-type promoter. DNAse footprinting experiments with purified UBF, an RNA polymerase I transcription factor, demonstrated the importance of the bases between -106 and -101 for the binding of that factor, providing a positive correlation between the transcription experiments and the binding of UBF to the rDNA promoter.

Animals↗
PubMed1992

IL-10, T lymphocyte inhibitor of human blood cell production of IL-1 and tumor necrosis factor.

We have identified and purified a factor that inhibits the production of IL-1 beta and TNF by stimulated human mononuclear cells. The activity is produced by the T cell lines Hut-78 and Mo constitutively under serum-free conditions. Crude conditioned media have titers of up to 100 U/ml (one unit defined as the reciprocal of the dilution producing 50% inhibition). The activity resides mainly in a single size peak of 30 to 35 kDa and an isoelectric point around 8. Other cytokines in this size range that have been reported to be inhibitory for IL-1 and TNF production include TGF-beta, IL-4, and IL-6; these factors were excluded by lack of detection, neutralizing antibody, and low activity compared with our factor. Another factor with these size and charge properties is IL-10, which inhibits T cell cytokine production. By polymerase chain reaction analysis, Mo and HuT-78 lines contain IL-10 transcripts whereas JURKAT is negative; this correlates with inhibitor bioactivity from the three lines. Use of mAb specifically showed the inhibitor to be IL-10.

Antibodies, Monoclonal↗
PubMed1992

Longitudinal study of gall stone prevalence at necropsy.

A prospective study of the prevalence of gall stone disease at necropsy in a stable population has been undertaken over a 10 year period up to June 1988. In women, the prevalence of gall stone disease remained static but in men aged 50-59 years it rose from 7% (n = 148) in the first three years to 18% (n = 138) in the last three years (p less than 0.01) and in men aged 60-69 it rose from 12% (n = 370) to 20% (n = 366, p less than 0.01). In the latter age group the female: male ratio fell from 2:1 to 0.8:1. The proportion of deaths from coronary heart disease in men fell slightly in those over 70 during the study period. There was a fall in deaths from coronary heart disease in all age groups in women. Men with gall stones were less likely to have had a cholecystectomy than women, and overall 88% of gall stones remained in situ. In a parallel clinical study, the number of cholecystectomies carried out in the same district fell by 18% over the 10 years without any apparent change in the provision of resources. Cholecystectomy remained almost three times more frequent in women. National data indicate that there have been major changes in the average diet before and during the period of study in favour of reducing coronary heart disease. There has been no change in mortality from coronary heart disease in young men but if the observed increase in the prevalence of gall stones in men and the decrease in deaths from coronary heart disease in women are real phenomena, it seems likely that they are diet related.

Age Factors↗
PubMed1991

Evaluation of a competitive NMDA antagonist (D-CPPene) in feline focal cerebral ischemia.

The effects of a competitive, N-methyl-D-aspartate (NMDA) receptor antagonist, D(-)E-4-(3-phosphonoprop-2-enyl)-piperazine-2-carboxylic acid (D-CPPene), on the volume of ischemic brain damage was assessed by quantitative histological study in 35 chloralose-anesthetized cats. Focal cerebral ischemia was produced by permanent occlusion of one middle cerebral artery and the animals were killed by transcardiac perfusion fixation 6 hours later. Pretreatment with D-CPPene (1.5, 4.5, or 15 mg/kg, administered intravenously 15 minutes prior to occlusion, with subsequent drug infusions to maintain a plateau in the plasma drug concentrations) effected dose-dependent reductions in the volume of ischemic brain damage. At the highest dose studied (15 mg/kg, plus an infusion of 170 micrograms/kg/min), D-CPPene reduced the volume of ischemic damage in the cerebral cortex by more than 75% compared to vehicle-treated control animals. The plasma concentration of D-CPPene, which is associated with a half maximal reduction in the volume of ischemic damage, was estimated to be 24 micrograms/ml during the initial 120 minutes after the middle cerebral artery occlusion. Treatment with D-CPPene (15 mg/kg, plus an infusion of 170 micrograms/kg/min) initiated 1 hour after occlusion reduced the volume of ischemic brain damage in the cerebral cortex by 30%, but this response did not achieve statistical significance. Precise definition of dose dependency for the anti-ischemic effects of NMDA antagonists and the therapeutic time window are influenced greatly by brain pharmacokinetics of the agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

A large intrathoracic parathyroid adenoma.

A case is described in which an unusually large parathyroid adenoma was visible on the plain chest radiograph taken during the investigation of hypercalcaemia. This was diagnosed preoperatively and a scheme is suggested whereby such a disgnosis can now readily be made. The differential diagnosis is discussed ant the literature is reviewed.

Adenoma↗
PubMed1976

Benign and malignant teratomas in children: analysis of 85 patients.

Teratomas were observed in 85 infants and children. Fifty-eight (68%) were girls and 27 (32%) boys. Site of origin was sacrococcygeal in 55 patients (64.8%), mediastinal in ten (11.7%), gonadal in ten (11.7%), presacral in four (4.8%), retroperitoneal in three (3.5%), and cervical in three (3.5%). Sixty-seven (78.8%) teratomas were benign and 18 (21.1%) malignant. Malignant tumors were noted in 11 of 55 sacrococcygeal (20%), two of ten mediastinal (20%), three of eight ovarian (37.5%), and both testicular lesions. Cervical, retroperitoneal, and presacral tumors were benign. Age at diagnosis (greater than 1 month), presence of symptoms (urinary and colonic obstruction), and serum positive for alpha fetoprotein were indicators of malignancy in sacrococcygeal cases. Age was not a factor for teratomas at other sites. Tumor size, presence of calcification, and gross appearance (cystic or solid) did not relate to the tumor's benign or malignant nature. Three of four presacral tumors were associated with anorectal anomalies. Operative resection is the treatment of choice. Four deaths were related to operative hemorrhage. Four of five survivors with malignant teratoma received radiation and chemotherapy. A more aggressive role for combined adjunctive measures is suggested in cases of malignancy.

Abdominal Neoplasms↗
PubMed1975

The effect of "ouabain" on the ultrastructure of cerebral arterioles and surrounding tissue, studied by a cannulation of a cerebral artery.

A technique for cannulation of a parietal branch of the middle cerebral artery is described by which high but local concentrations of substances can be achieved in cortical vessels. Using this technique it was shown that ouabain, a specific inhibitor of the Na+-K+-ATPase enzyme system, can produce alterations in the blood brain barrier (BBB) permeability as seen by the passage of Evans Blue into cortical tissue. Electron microscopy revealed changes in the endothelium of cerebral arterioles ranging from an increase in the number of vesicles and vacuoles to complete breakdown of cytoplasm and membranes. Swelling of the peri-arteriolar end feet of protoplasmic astroglia and of dendrites was characteristic of tissue surrounding affected arterioles. Swollen fibrous astrocytes, oligodendrocytes and microglia were not seen even in areas of vasogenic edema. These results are discussed in terms of current ideas of the BBB and astroglial function.

Animals↗