Biomedical subjects

B S Wilson

Publications and source records attributed to B S Wilson.

At least 73 records · Page 4Linked to original sources

PubMed1989

Depletion of guanine nucleotides with mycophenolic acid suppresses IgE receptor-mediated degranulation in rat basophilic leukemia cells.

In RBL-2H3 rat basophilic leukemia cells, Ag that crosslink IgE-receptor complexes stimulate the turnover of inositol phospholipids, the mobilization of Ca2+ from intra- and extracellular sources, the release of serotonin and other substances from granules and the transformation of the cell surface from a microvillous to a lamellar architecture. This study explores the role of GTP-binding proteins (G proteins) in the control of these biochemical and functional responses. We report that incubating RBL-2H3 cells for 4 h with 10 microM mycophenolic acid (MPA), an inhibitor of de novo GTP synthesis, reduces GTP levels by over 60% and causes an average reduction of 50% in Ag-stimulated serotonin release. This inhibition of secretion is associated with a 50% decrease in the rate of 45Ca2+ influx in MPA-treated cells. In contrast, Ag-stimulated inositol trisphosphate production is only slightly reduced, indicating that the phosphatidylinositol-specific phospholipase C can be activated by Ag in GTP-depleted cells. The membrane responses to IgE receptor cross-linking are unaffected by incubating cells with MPA. Exogenous guanine or guanosine protects the GTP pools in MPA-treated cells and permits normal ion transport and secretory responses to Ag; adenine does not. These results implicate a guanine nucleotide-binding protein in the control of IgE receptor-dependent signal transduction in RBL-2H3 cells. This protein may particularly control the Ca2+ influx pathway that is essential for secretion.

Animals↗

PubMed1989

Validity of the observation of children's physical activity.

An observational method for quantifying intensity of activity was validated against min-by-min heart rates during physical education periods. The mean heart rate values increased as the activity points increased. Moderate average correlations were obtained between the min-by-min activity points and heart rates. A time series regression analysis accounted for 72% of the variance in heart rate values with a model combining heart rate in the previous min and activity points. Further work on estimates of average metabolic units for activity categories will enable future investigators to obtain more precise estimates of energy expenditure from this observation system.

Child↗

PubMed1989

Pneumothorax: appearance on lateral chest radiographs.

The appearance of pneumothorax on lateral radiographs obtained with the patient erect were reviewed in 100 patients (122 total examinations). A pneumothorax could be seen on the lateral projection in 89% of the examinations (109 of 122). The displaced pleural line was most frequently identified anteriorly or posteriorly and was less commonly identified at the lung apex or in a subpulmonic location. In 11 cases, an air-fluid level was the only recognizable finding of a pneumothorax on the lateral projection. Although in 27% of examinations (32 of 122) the pneumothorax was either not seen (11%) (n = 13) or was a subtle finding (16%) (n = 19), in 14% of examinations (17 of 122) the lateral projection provided helpful information to supplement the posteroanterior projection.

Adult↗

PubMed1988

The intraperitoneal delivery of radiolabeled monoclonal antibodies: studies on the regional delivery advantage.

The i.p. delivery of murine monoclonal antibody was compared with i.v. delivery in normal mice and rats, in normal nude mice and in those with i.p. human ovarian carcinoma xenografts. In normal rats, all classes of antibodies and antibody fragments evaluated were cleared from the peritoneal cavity at comparable rates. The regional delivery (Rd1) advantage to the peritoneal cavity following i.p. delivery was thus most dependent on the rate of clearance of the antibody or fragment from the blood stream. Determining the exact i.p. delivery advantage was problematic due to the difficulty in reliably obtaining peritoneal fluid later than 9-10 h after i.p. injection in normal animals. During the first 9 h following i.p. injection, the Rd(0-9/0-9) was, for a murine IgG2ak Fab greater than F(ab')2 greater than IgG (at 13.6 greater than 10 greater than 7.9). Two murine IgMs evaluated differed in Rd(0-9) at 27.1 and 9.2 respectively. When blood levels were extrapolated to infinity, these Rd (0-9/affinity) values were considerably lower with the Fab having the highest Rd at 4.67. The i.p. Rd advantage was almost solely due to the i.p. antibody levels seen in the first 24 h after injection, as after that time, blood levels become comparable to those seen following i.v. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. or i.v. injection in rats showed comparable levels of radioantibody activity, whether the injection was i.p. or i.v. (except for higher diaphragmatic levels following i.p. delivery). In nude mice with i.p. human-derived ovarian tumors, intact IgG clearance from the peritoneal cavity to the blood was considerably slower than in normal animals, and early i.p. tumor uptake of specific antibody was significantly higher than that following i.v. antibody delivery. With higher early tumor uptake and lower systemic exposure, early tumor/nontumor ratios were significantly greater than those for i.v. delivery, though not beyond 48 h after i.p. injection. This study demonstrates the pharmacokinetic rationale for i.p. monoclonal antibody delivery, especially for agents cleared rapidly from the blood, such as antibody fragments. In addition, definite i.p. delivery benefit for antibody specific to i.p. tumors in the i.p. ovarian cancer system was shown soon after injection. These data regarding i.p. antibody delivery should be useful in rationally planning diagnostic and therapeutic studies involving the i.p. delivery of unmodified and immunoconjugated monoclonal antibodies.

Animals↗

PubMed1988

Radiolabeled antibodies, albumin and antimony sulfide colloid: a comparison as lymphoscintigraphic agents.

The kinetics of lymph node and systemic uptake of members of three different classes of lymphoscintigraphic agents were studied in normal laboratory rats. 99mTc antimony trisulfide colloid (TcSbC), 99mTc human serum albumin (TcHSA), 125I 5G6.4 (a murine IgG2ak monoclonal antibody), 125I 763.24T (a murine IgG1), and 125I FT166 ( a murine IgM monoclonal) all current or potential lymphoscintigraphic agents, were injected subcutaneously into the hind foot pads of healthy rats. Ipsilateral and contralateral popliteal lymph nodes were sampled up to 4 h post-injection. Subcutaneous injection resulted in far higher nodal uptake for all agents than i.v. delivery with ipsilateral popliteal node/blood ratios 1 h postsubcutaneous injection of: for TcSbC (1900) greater than 125I IgM (497) greater than TcHSA (72) greater than 125I Intact IgG2a or 125I IgG1 at approximately 10. Thus, while all agents achieve popliteal node/blood ratios far greater than unity, TcSbc has the greatest absolute and relative nodal accumulation, greater than the 125I IgM monoclonal antibody and TcHSA. Uptake of the intact 125I IgG antibodies is lowest. These data suggest that TcSbC in particular, as well as TcHSA and IgM may be most useful as non-specific nodel imaging agents, while the lower background activity of the IgGs may make targeting specific antigen in nodes more feasible.

Animals↗

PubMed1988

Comparative studies of speech processing strategies for cochlear implants.

A wide variety of speech processing strategies for multichannel auditory prostheses were compared in studies of two patients implanted with the UCSF electrode array. Each strategy was evaluated using tests of vowel and consonant confusions, with and without lipreading. Included among the strategies were the compressed analog processor of the present UCSF/Storz prosthesis and a group of interleaved pulses processors in which the amplitudes of nonsimultaneous pulses code the spectral variations of speech. For these patients, each with indications of poor nerve survival, test scores were significantly higher with the interleaved pulses processors. We believe this superior performance was a result of 1. the substantial release from channel interactions provided by nonsimultaneous stimuli and 2. a fast enough rotation among the channels to support adequate temporal and spectral resolution of perceived speech sounds.

Cochlear Implants↗

PubMed1987

High-dose, unlabeled, nonspecific antibody pretreatment: influence on specific antibody localization to human melanoma xenografts.

Nonspecific uptake of radiolabeled monoclonal antibodies in normal tissues is a significant problem for tumor imaging. A potential means of decreasing nonspecific antibody binding is to "blockade" nonspecific antibody binding sites by predosing with cold, nonspecific isotype-matched antibody, before injecting specific antibody. Nontumor-specific murine monoclonal antibody LK2H10 (IgG1) or Ab-1 (IgG2a) was given i.v. at doses of 0 to 3.5 mg to nude mice with xenografts of human melanoma. These mice were then given i.v. 4 micrograms of 131I anti-high molecular weight antigen of melanoma (HMWMAA) monoclonal antibody 763.24T (IgG1) or 225.28S (IgG2a), respectively. These mice were also given a tracer dose of 125I LK2H10 or Ab-1, respectively. Specific tumor uptake of anti-HMWMAA antibodies was see in all cases. No drop in tumor or nontumor uptake was demonstrated for either of the tumor-specific or nonspecific monoclonal antibodies due to nonspecific monoclonal antibody pretreatment. These data suggest that high doses of isotype-matched unlabeled nonspecific monoclonal antibody given before 131I tumor-specific monoclonal antibody, will not enhance tumor imaging.

Animals↗

PubMed1986

Inhibition of B cell growth factor (BCGF) by monoclonal antibodies directed against the C3d receptor (CR2).

Normal human B cell proliferation is controlled by various immunoregulatory signals including the T cell-derived lymphokine B cell growth factor (BCGF). Human BCGF provides the final proliferative signal to normal, activated B cells. We herein show that anti-CR2 monoclonal antibodies inhibit human B cell responsiveness to purified BCGF. Addition of anti-CR2 antibody, AB5, was capable of completely inhibiting BCGF-mediated enhancement of either anti-mu or staphylococcal protein A-activated human B cells (191 +/- 21 cpm vs. 3942 +/- 622 cpm, mean +/- SEM). Inhibition of B cell response to BCGF by AB5 occurred in a dose-dependent manner. Monoclonal antibody anti-B2, which recognizes the same 140-kDa glycoprotein as AB5, in comparable concentrations also inhibited B cell responsiveness to BCGF. Monoclonal antibodies of the same subclass (IgG1) showed no inhibitory effect on BCGF enhancement of B cell proliferation. The F(ab')2 fragment of AB5 generated by pepsin digestion was similarly inhibitory as was the intact Ig. AB5-mediated inhibition was independent of the target B cell state of activation. Both resting and activated B cells (anti-mu or staphylococcal protein A activated) incubated with similar concentrations of AB5 were unresponsive to BCGF. The ability of anti-CR2 antibodies to block BCGF-dependent B cell proliferation suggests that occupancy of C3d membrane receptors may result in modulation of B cell proliferation in physiologic or clinical disease states.

Antibodies, Monoclonal↗

PubMed1986

Chromogranin from normal human adrenal glands: purification by monoclonal antibody affinity chromatography and partial N-terminal amino acid sequence.

A method is presented for the purification of human chromogranin from adrenal glands obtained at autopsy. The procedure involved homogenization of whole glands in aqueous buffer, salt precipitation, affinity chromatography using a highly specific monoclonal antibody (LK2H10) and reverse-phase high-pressure liquid chromatography. Chromogranin purified from autopsy adrenal glands revealed a high degree of polypeptide heterogeneity when analyzed by silver-stained SDS polyacrylamide gels. Greater than 90% of the protein was represented by a cluster of polypeptides with an Mr = 70 000 (i.e. chromogranin A), while the remaining protein was highly disperse in molecular weight. That these various polypeptides were in fact chromogranin was shown by Western blotting using monoclonal antibody LK2H10. About 6 nmol of chromogranin were obtained from 97 g of starting adrenals which was estimated to be a 25% yield and a 250-fold enrichment from adrenal homogenates. Critical to achieving reasonable yields of this protein was the need for particular low pH buffers for resuspension of chromogranin after solvent removal steps. Chromogranin purified from human adrenal glands was similar in amino acid composition, and identical in the N-terminal amino acid sequence (24 residues) to bovine chromogranin A. A secondary sequence representing 25% of the total protein and missing the first three residues of the N-terminus suggested the possibility of N-terminal processing of chromogranin in situ. The conservation of the N-terminal amino acid sequence of human and bovine chromogranin contrasts with the strong sequence variability predicted by antisera cross-reactivity and suggests that the N-terminus of chromogranin may be critical for its biological activity.

Adrenal Glands↗

PubMed1986

The influence of monoclonal antibody dose on tumor uptake of radiolabeled antibody.

The impact of antibody protein dose on tumor accumulation of radiolabeled monoclonal antibody was studied in nude mice with xenografts of human melanomas. 225.28S, a murine monoclonal antibody reactive with a high-molecular weight antigen of melanoma, was radiolabeled with I-125 and administered intraperitoneally to nude mice with human melanoma xenografts. Three days later, the animals were sacrificed, and tumor and normal tissue uptake of I-125 antibody was determined. At doses of 6.25, 62.5, 625 and 1875 ug of monoclonal antibody, there were no significant differences in percent of injected dose reaching the tumor/g of tumor or in the non-tumor uptakes achieved. These findings indicate that in the melanoma system, antibody dose is not a critical determinant of tumor uptake, and additionally indicate that low doses of antibody protein are appropriate for studies involving radioiodinated antibody localization.

Animals↗

PubMed1986

Gut endocrine cell population in coeliac disease estimated by immunocytochemistry using a monoclonal antibody to chromogranin.

Abnormalities of gut endocrine responses, as well as changes in the number of different endocrine cell types, have been reported convincingly in coeliac patients. Nevertheless, no estimation of total numbers of gut endocrine cells has yet been made in well defined groups of coeliacs. In this study, we have visualised all endocrine cell types in jejunal biopsies from coeliac patients with active and quiescent disease as well as in controls, using a monoclonal antibody to chromogranin. This protein was purified originally from bovine adrenal medulla and is known to be a reliable marker for all endocrine cells of the gut. The following groups were considered: (a) nine coeliacs with active illness, (b) 10 coeliacs under gluten-free diet, (c) eight coeliacs receiving gluten challenge, (d) five non-coeliacs (controls). Histological (haematoxylin and eosin) and immunocytochemical (peroxidase anti-peroxidase) stains were applied to 3 micron paraffin sections. Quantitative estimation of endocrine cell density was made using four different methods in order to evaluate the results fully (number of cells/mm2, number of cells/visual field, number of cells/8 crypts-villi, number of cells/unit of length of muscularis mucosae). In patient groups (a) and (c), coeliacs with active disease and coeliacs on gluten challenge diet respectively, a significantly higher number of endocrine cells was observed in comparison with normal controls (group d). In group (b) patients, coeliacs on gluten-free diet, no significant changes in the number of endocrine cells were observed in comparison with controls. Our results show that a significant increase in endocrine cell density exists in coeliacs with active illness (groups a and c), in comparison with controls. This condition is resolved in coeliacs receiving a gluten-free diet (group b).

Antibodies, Monoclonal↗

PubMed1986

Prolactin and growth hormone synthesis and thymidine incorporation in dissociated rat pituitary tumor cells.

The effect of in vivo diethylstilbestrol (DES) treatment on the MtT/W15 transplantable pituitary tumor was examined in dissociated pituitary cells by measuring the rate of incorporation of [3H]thymidine into DNA and the synthesis of prolactin (PRL) and growth hormone (GH) as assessed by the rate of incorporation of [3H]leucine. MtT/W15 transplantable pituitary tumors from rats treated for 3 weeks with DES showed significant reduction in the extent of [3H]thymidine incorporation compared with tumor cells from untreated rats (2231 +/- 182 vs 172 +/- 17 dpm/10(5) cells; n = 3). In addition, tumor cells from DES-treated rats showed a significant increase in GH synthesis compared with tumor cells from untreated rats. In contrast to these findings, dissociated pituitary cells from non-tumor-bearing rats given 10 mg DES in Silastic tubing for 3 weeks showed a three-fold increase in PRL synthesis compared to cells from untreated control rats (29.3 +/- 1.5 vs 10.0 +/- 0.9% of total radioactivity in gel; n = 3. There was also a four-fold increase in the rate of [3H]thymidine incorporation after DES-treatment in non-tumor-bearing rats (695 +/- 114 vs 178 +/- 13.9 dpm/10(5) cells; n = 3). These results indicate that DES inhibits MtT/W15 pituitary tumor cell proliferation, while stimulating synthesis of GH.

Animals↗

PubMed1986

Mediation of IgA induced lung injury in the rat. Role of macrophages and reactive oxygen products.

Acute lung injury in the rat has been induced by the instillation of affinity-purified mouse monoclonal IgA antibody with specific reactivity to the hapten dinitrophenol coupled to albumin. As previously reported, this model of lung injury requires an intact complement system but is independent of neutrophils. In contrast to macrophages obtained by bronchoalveolar lavage from rats receiving IgA into the airways in the absence of intravenously injected antigen, macrophages obtained from the lungs of rats developing IgA immune complex-induced lung injury were significantly increased in number, showed greater spontaneous generation of O2.-, and demonstrated significantly enhanced O2.- responses in the presence of an added stimulus, phorbol ester. Inhibition studies in vivo suggested that the IgA-induced lung injury is mediated by oxygen radicals generated from lung macrophages. Pretreatment of animals with superoxide dismutase, catalase, the iron chelator, deferoxamine, or the hydroxyl radical scavenger, dimethyl sulfoxide, suppressed the development of lung injury. Morphologically the lungs of protected animals showed increased numbers of mononuclear cells within the alveolar compartment but little evidence of alveolar or capillary injury, in contrast to unprotected animals in which there was evidence of severe injury, both to microvascular interstitial endothelial cells as well as to alveolar lining epithelial cells. These studies suggest that acute lung injury in the rat induced by IgA immune complexes is mediated by oxygen radical formation and that the macrophage may be the principle effector cell, as compared to IgG immune complex induced lung injury, which is also oxygen radical mediated but in which the neutrophil is the effector cell.

Animals↗

PubMed1985

Medullary carcinoma of the thyroid. An immunocytochemical and histochemical study of 25 cases using eight separate markers.

The current study was undertaken on 25 cases of thyroid medullary carcinoma to compare the diagnostic value of calcitonin with other peptides including PDN-21, the C-terminal flanking peptide of human calcitonin within the calcitonin precursor, and calcitonin gene-related peptide, CGRP. Antiserum raised to chromogranin, an acidic protein of 68,000 daltons, was also used to compare its diagnostic value as a general marker for neuroendocrine neoplasia with neuron-specific enolase (NSE) and Grimelius' argyrophil silver staining. Immunocytochemistry was performed using the peroxidase-antiperoxidase method at the light microscopic level and the immunogold staining procedure at the ultrastructural level. All tumors were reactive to calcitonin and CGRP antisera, whereas PDN-21 was present in 23 cases. It was also found that these peptides were colocalized in the majority of C-cells. The intensity and specificity of CGRP and PDN-21 immunoreaction was comparable to and in some cases even better than that obtained with calcitonin antiserum. In the majority of tumors, somatostatin and bombesin immunoreactivity was either absent, weak, or variable in intensity and distribution. The current study thus demonstrates that together with calcitonin, PDN and, in particular, CGRP antisera may be applied to corroborate immunocytochemical diagnosis in medullary carcinoma of the thyroid. With regard to general neuroendocrine markers, Grimelius' and chromogranin provided the most consistent results. NSE isoenzyme immunoreactivity, on the other hand, was more variable, probably reflecting the metabolic state of the tumor cells.

Bombesin↗

PubMed1985

Fragmentation and polymeric complexes of albumin in human urine.

Analysis of urine proteins of some individuals with proteinuria by SDS-PAGE and silver staining revealed protein bands in urine which did not appear to be present in plasma. The bands migrated with apparent molecular weights of 260 000, 180 000, 110 000, 45 000, 40 000, 30 000, 24 000, 18 000 and 11 000. These bands were shown to be albumin polymer and fragments by using a polyclonal antibody to (a) immunoprecipitate radiolabelled urine proteins, and (b) identify bands blotted from SDS-PAGE gels onto nitrocellulose paper. The specificity of the polyclonal anti-albumin antibody was confirmed by using two mouse monoclonal antibodies raised against human albumin which, between them, recognized the same protein bands on nitrocellulose paper as did the polyclonal antibody. The results of these studies of albumin in human urine confirm that albumin exists as polymer and also show that albumin fragmentation occurs in urine. Fragmentation occurs by proteolysis of the albumin molecule both at sites within and outside disulfide loops. The predominant cleavage site appears to be approximately two-fifths of the distance from one end of the albumin molecule to produce disulfide-linked fragments of about 45 000 and 30 000 molecular weight.

Albuminuria↗

PubMed1985

Ultrastructural localization of chromogranin: a potential marker for the electron microscopical recognition of endocrine cell secretory granules.

Using a monoclonal antibody (LK2H10) directed against human chromogranin, we have been able to localize this soluble glycoprotein to the matrix of secretory granules from a wide variety of endocrine cells. In the gut, enterochromaffin, enteroglucagon, glucose-dependent insulinotropic peptide, gastrin, and neurotensin-containing cells exhibit chromogranin immunoreactivity. In our system, chromogranin-immunoreactive material was restricted to the halo of human pancreatic glucagon-containing secretory granules within A-cells. Chromogranin immunoreactivity was also localized to secretory granules in phaeochromocytomas, gastrinomas, medullary carcinomas of the thyroid and a carotid body tumour (chemodectoma). Chromogranin is proposed as a potential marker for the ultrastructural recognition of endocrine cell secretory granules.

Adolescent↗

PubMed1985

Chromogranin: a newly recognized marker for endocrine cells of the human gastrointestinal tract.

Existing methods for the histochemical demonstration of gastrointestinal cells are somewhat limited. Chromogranin represents a family of proteins that coexist with catecholamines in the secretory vesicles of adrenal medulla cells. In the present study, immunocytochemistry was used to test whether chromogranin is a marker for gut endocrine cells. Serial sections of each area of human gut were immunostained for chromogranin and for the amine and each of the peptides known to be present in mucosal endocrine cells. Chromogranin was immunostained in large numbers of endocrine cells in all tissues examined. All identified endocrine cell types were found, in serial sections or by sequential silver impregnations, to be chromogranin immunoreactive. However, the possibility exists that some chromogranin-immunoreactive cells contain a yet to be discovered endocrine substance. Immunostaining of chromogranin thus appears to provide a means for demonstrating all gastrointestinal mucosal endocrine cells identifiable by the methods described in this study.

Chromogranins↗

PubMed1985

Echo intensity compensation by echolocating bats.

When mounted on a swinging pendulum, mustache bats, Pteronotus p. parnellii, emit ultrasonic pulses as they move toward and away from fixed targets. During forward swings they systematically decrease the intensity of their emitted pulses and during backward swings they increase the intensity. In this way, echo strength is continuously adjusted and apparently optimized for signal analysis. We have called this behavior echo intensity compensation. Pteronotus simultaneously Doppler and echo intensity compensate during forward swings of the pendulum but during backward swings they only echo intensity compensate. Pteronotus can regulate the intensity of both the constant frequency and frequency modulated components of their pulses; this regulation is independent of vestibular cues, pulse repetition rates, pulse durations and pulse-echo intervals.

Animals↗