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Biomedical subjects

J R Baker

Publications and source records attributed to J R Baker.

At least 235 records · Page 13Linked to original sources
PubMed1987

c-myc expression in the thyroid. II: Thyrocytes and peripheral and intrathyroidal lymphocytes from patients with autoimmune thyroid disease.

Enhanced oncogene expression observed in lymphocytes from patients with systemic lupus erythematosus has suggested the importance of studying oncogene expression and regulation in the cellular events of autoimmune thyroid diseases (AITD). The present study examines oncogene expression in peripheral and intrathyroidal lymphocytes from patients with Hashimoto's disease (HD) and Graves' disease (GD). Intrathyroidal lymphocytes from a patient with primary thyroid lymphoma were also examined. Lymphocytes were isolated by Ficoll-Hypaque gradients, and total RNA was prepared by extraction with guanididium thiocyanate and ultracentrifugation through a cesium chloride cushion. RNA concentrations were determined by O.D. readings at 260/280 nm and each sample subjected to gel electrophoresis with ethidium bromide staining to assure the integrity of the RNA. 30 micrograms total RNA was size fractionated on a 1% (w/v) agarose/formaldehyde gel and transferred to nylon membranes. These membranes were hybridized with nick-translated 32P labelled c-myc DNA (exon III), washed at high stringency and subjected to autoradiography. Specific bands were quantitated by scanning densitometry. Five RNA samples from GD thyroids had 2.4 Kb bands corresponding to c-myc with a mean O.D. (+/- SD) of 0.76 +/- 0.23, whereas 7 from normal thyroid glands had mean O.D. of 1.0 +/- 0.26. Peripheral lymphocytes from 7 GD patients had a mean O.D. of 1.41 +/- 0.25, 4 HD patients had a mean O.D. of 1.05 +/- 0.10 and 2 normal patients had a mean O.D. of 1.4 +/- 0.14. The readings for a sample obtained from intrathyroidal lymphocytes of a patient with HD and thyroid lymphoma were 1.0 and 1.4, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoimmune Diseases↗
PubMed1986

The primary structure of link protein from rat chondrosarcoma proteoglycan aggregate.

Cartilage proteoglycan monomers associate with hyaluronic acid to form proteoglycan aggregates. Link protein, a glycoprotein interacting with both hyaluronic acid and proteoglycan, serves to stabilize the aggregate structure. The primary structure of the link protein has been determined with a view to defining its interaction with both hyaluronic acid and proteoglycan. Thus, the link protein has been digested with staphylococcal V8 protease, trypsin, and chymotrypsin and the resulting peptides characterized by amino acid composition and sequence. We have determined that the link protein is a single peptide with 339 amino acid residues. The protein core has a molecular weight of 38,564. There is one N-linked oligosaccharide at residue 41 with a molecular weight of approximately 2,500. There are five disulfide bonds which define three loops within the amino acid sequence. The loop nearest to the NH2-terminal contains 78 amino acids and is followed by a section of 42 amino acids between it and the second loop. The second and third loops display considerable homology with each other; they consist of 71 and 70 amino acids, respectively, each contain two disulfide bonds, and both loops possess, approximately centrally, an epitope for the species nonspecific anti-link protein monoclonal antibody, 8A4. These loops are separated by a short section of 27 amino acids. We speculate that these loops are functionally important in the interaction of link protein with hyaluronic acid, as they appear to be the most conserved regions of link protein between species.

Amino Acid Sequence↗
PubMed1986

Articular cartilage proteoglycans from normal and osteoarthritic mice.

Articular cartilage proteoglycans from an osteoarthritic mouse strain, STR/IN, were labeled in vivo with 35S-sulfate and characterized with respect to extractability, ability to aggregate, size of monomer and glycosaminoglycan chains, sulfation of glycosaminoglycans, relative amounts of chondroitin-4 sulfate and chondroitin-6 sulfate, and link proteins. The proportion of 35S-labeled proteoglycans extractable by 0.4M guanidine hydrochloride was the same in control and osteoarthritic animals. However, a greater proportion was extractable by 4M guanidine hydrochloride in the STR/IN animals as compared with the control mice. The ability of the 35S-proteoglycans to aggregate was comparable in controls and osteoarthritic mice, as judged by their exclusion on Sepharose CL-2B. Monomers from both controls and osteoarthritic animals eluted from Sepharose CL-2B with a KAV of 0.47. Glycosaminoglycans from control and osteoarthritic animals eluted from Sepharose CL-6B with a KAV of 0.63, and no differences in sulfation or chondroitin-4 sulfate content were found. Aggregates were immunoprecipitated with link protein-specific antiserum, and only link protein 2 was found in aggregates from control and osteoarthritic animals.

Animals↗
PubMed1986

Serum fructosamine: a screening test for diabetes in pregnancy.

Serum fructosamine levels were measured in 1200 pregnant women at different stages of gestation, 167 of them having a glucose tolerance test. There was a significant fall in fructosamine levels throughout pregnancy and details of normal values at different gestational stages are presented. A good correlation was found between fructosamine and glucose tolerance test (r = 0.813). Nine women had gestational diabetes diagnosed by glucose tolerance test and eight of those had a serum fructosamine level greater than the ninety-fifth percentile. This study confirms our previous findings that serum fructosamine may be a useful screening test for gestational diabetes.

Adolescent↗
PubMed1986

Marihuana-induced embryotoxicity in the rabbit.

Few teratogenic studies in animals have been performed simulating marihuana smoking in man. An inhalation marihuana teratology study was conducted in albino rabbits utilizing a modified automatic smoking machine originally developed for rats and mice. Appropriate numbers of dams were exposed to 4 puffs (0.14 mg/kg), 8 puffs (0.72 mg/kg), or 16 puffs (1.44 mg/kg) once daily during gestation Days 6 to 18, and sacrificed on Day 28. Control dams were exposed to 12 puffs of placebo cigarettes or sham-treated for a similar duration in the absence of any smoke. Consistency of smoke was monitored by cigarette weights, total particulate matter, concentrations of carbon monoxide (CO), and tetrahydrocannibinol (THC) in smoke, carboxyhemoglobin levels, and plasma THC levels. Except for a transient decrease in dam respiration rates, other gross toxic signs were absent. Reproductive parameters of mothers were generally normal except for a dose-related embryotoxicity predominantly associated with early resorptions. Despite twice the number of embryo/fetal deaths, there were no marihuana soft tissue or skeletal defects. A correlation between dam demises and CO levels among placebo-exposed animals was related to greater quantities of CO being generated during placebo combustion. It has been shown in the rabbit that marihuana is embryotoxic and not a teratogen at plasma THC levels found in human females.

Animals↗
PubMed1986

Development of circulating antiheart antibodies as a result of coronary bypass surgery.

Antiheart antibodies have been implicated as a marker of postcardiotomy syndrome in patients undergoing coronary artery bypass. To assess the frequency of and contributory factors in the development of antiheart antibodies after coronary bypass procedures, 33 patients were examined for evidence of antiheart antibodies before and for seven days after routine coronary artery bypass operations. Overall titers of antiheart antibodies rose in approximately 66% of the patients. However, this rise was not accompanied by any major clinical symptoms. History of previous myocardial infarction or myocardial injury did not correlate with a higher frequency of development of antibodies. Antiheart antibodies appear to be a common consequence of coronary artery bypass operations and are not routinely associated with the development of postcardiotomy syndrome.

Adult↗
PubMed1986

Determination of an optimal forecast model for ambulance demand using goal programming.

A multistep approach to determining the optimal parameters of an exponential smoothing model was used to forecast emergency medical service (E.M.S.) demand for four counties of South Carolina. Daily emergency and routine (non-emergency) demand data were obtained and forecast statistics generated for each county sampled, using Winters' exponential smoothing model. A goal programme was formulated to combine forecast results for emergency calls with routine call forecasts. The goal programme gave a higher priority to accurate forecasting of emergency demand. The forecast model generated implicitly weights demand by severity and provides a reliable estimate of demand overall. The optimal parameter values for the smoothing model were obtained by minimizing the objective function value of the goal programming problem. The parameter values obtained were used to forecast demand for E.M.S. in the selected counties. The results of the model were compared to those using a multiple linear regression model and a single-objective-based exponential smoothing model for 2 months of data. When compared with two single-objective forecast models, the multiple-objective approach yielded more accurate forecasts and, therefore, was more cost-effective for the planner. The model presents and demonstrates a theoretical approach to improving the accuracy of ambulance demand forecasts. The possible impact of this approach on planning efficiency is discussed.

Ambulances↗
PubMed1986

Killer cell activity and antibody-dependent cell-mediated cytotoxicity are normal in Hashimoto's disease.

Antibody-dependent cell-mediated cytotoxicity (ADCC) is the process by which antibodies interact with killer cells to effect cell lysis, whereas natural killing (NK) refers to the ability of peripheral blood killer cells to lyse target cells in the absence of specific antibody. The purpose of the present study was to determine if either NK cells or ADCC might play a role in the development of Hashimoto's thyroiditis (HD) by testing the ability of killer cells to cause lysis of K562 erythroleukemia tumor cells and human thyrocytes in the presence and absence of serum from normal and HD patients. Using K562 target cells, NK activity was 70 +/- 4% (mean +/- SEM) for HD effector cells and 66 +/- 5% for normal effector cells at an effector to target ratio of 100:1. Similarly, with thyrocytes as targets, effector cells from HD patients (38 +/- 3%) and normal subjects (34 +/- 5%) caused comparable lysis (at an effector to target ratio of 100:1). Using K562 target cells, ADCC was 35% when effector cells from HD or normal subjects were coincubated with either normal or HD sera. Using thyrocyte target cells, lysis was about 25-30%, but, again, no differences were found between HD and normal effector cells or serum. There was a significant correlation between lysis for K562 and thyrocyte target cells, but there was no significant correlation between the titer of serum antithyroid microsomal antibodies and specific lysis. Intrathyroidal lymphocytes and peripheral lymphocytes from one patient with HD caused comparable lysis of labeled thyrocyte targets, as did normal peripheral lymphocytes. We conclude that ADCC and NK activities in peripheral lymphocytes were normal in HD patients and, therefore, may not have a primary role in mediating thyrocyte destruction in Hashimoto's thyroiditis.

Adult↗
PubMed1986

The alkaline reducing activity of glycated serum proteins and its relevance to diabetes mellitus.

We investigated the ability of the fructosamine assay to detect glycation of serum proteins. We incubated both whole human serum and serum protein fractions in vitro with [14C]glucose, and analyzed for reducing activity and for uptake of 14C by protein. In all experiments, the reducing activity increased linearly with time for seven days and was correlated with 14C uptake (r = 0.94-0.98). Protein ketoamines were about fivefold more actively reducing than equimolar concentrations of deoxymorpholinofructose, the fructosamine standard, which explains why values for fructosamine in serum are higher than the expected concentration of protein ketoamines. We also used [14C, 2-3H]glucose to assess the contribution of the aldimine component to 14C uptake. Whole human serum and albumin incubated with [14C, 2-3H]glucose showed little uptake of 3H in relation to 14C. We conclude that glycated protein can be simply and reliably quantified by the fructosamine assay, and we discuss the relevance of this conclusion to the monitoring of diabetes.

Blood Proteins↗
PubMed1985

An amino acid sequence common to both cartilage proteoglycan and link protein.

Cartilage proteoglycan monomers associate with hyaluronic acid to form proteoglycan aggregates. Link protein, interacting with both hyaluronic acid and proteoglycan, serves to stabilize the aggregate structure. In the course of determining the primary structure of link protein, two peptides produced by digestion of rat chondrosarcoma link protein with trypsin or chymotrypsin have been selectively purified by immunoaffinity chromatography on a column of monoclonal anti-link protein antibody (8A4) immobilized to Sepharose 4B. These peptides have been sequenced using the double-coupling dimethylaminoazobenzene isothiocyanate/phenyl isothiocyanate procedure. A consensus sequence, Cys-X-Ala-Gly-Trp-Leu-X-Asp-Gly-Ser-Val-X-Tyr-Pro-Ile-X-X-Pro, obtained by comparing the affinity-isolated tryptic peptide with the affinity-isolated chymotryptic peptide and an overlapping tryptic peptide, shows homology with a sequence obtained from the NH2-terminal of a CNBr peptide from proteo glycan core protein of bovine nasal cartilage: Ser-Ser-Ala-Gly-Trp-Leu-Ala-Asp-Arg-Ser-Val-Arg-Tyr-Pro-Ile-Ser-. We suggest that the common sequence is structurally important to the function of these proteins and may be involved in the binding of both link protein and proteoglycan to hyaluronic acid.

Amino Acid Sequence↗
PubMed1985

Monoclonal antibodies as probes for determining the microheterogeneity of the link proteins of cartilage proteoglycan.

Monoclonal antibodies were raised against Swarm rat chondrosarcoma link protein 2. Two of the resultant hybridomas (9/30/6-A-1 and 9/30/8-A-4) were used in structural analyses of the link proteins. The 9/30/6-A-1 monoclonal antibody recognized an epitope which was only present on rat chondrosarcoma link protein 2. This epitope was absent in rat chondrosarcoma link protein 3 obtained after trypsin or clostripain treatment of rat chondrosarcoma proteoglycan aggregate, indicating that proteolytic digestion either removed or modified the epitope. Contrasting this, the 9/30/8-A-4 monoclonal antibody recognized an epitope present in link protein(s) 1, 2, or 3 isolated from cartilage of several animal species (rat, bovine, human, and chicken). Rat chondrosarcoma link protein 2 was digested with Staphylococcus aureus V8 protease, and the resulting peptides were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subjected to immunolocation analyses. The 9/30/6-A-1 and 9/30/8-A-4 monoclonal antibodies recognized epitopes in two different halves of the link protein molecule. The 9/30/8-A-4 monoclonal antibody was used to identify proteolytic cleavage peptides common to the individual link proteins (1, 2, or 3) purified from cartilage proteoglycans of several animal species. Digestion of rat chondrosarcoma link protein 2 with endoglycosidase H or alpha-mannosidase increased its electrophoretic mobility to that of link protein 3 and removed or altered the determinant recognized by the 9/30/6-A-1 monoclonal antibody, indicating that a high-mannose oligosaccharide chain was part of the antigenic determinant. The 9/30/8-A-4 monoclonal recognition of epitope was unaffected by endo- or exoglycosidase treatment. Endo- and exoglycosidase treatment of bovine nasal cartilage link proteins also altered their electrophoretic mobility, indicating that high-mannose oligosaccharide structures on the various link proteins (1, 2, or 3) accounted for the microheterogeneity observed in sodium dodecyl sulfate-polyacrylamide gels.

Animals↗
PubMed1985

Use of carfentanil and a ketamine-xylazine mixture to immobilise wild grey seals (Halichoerus grypus).

Carfentanil was used to anaesthetise 46 adult grey seals (Halichoerus grypus) on 78 occasions during two breeding seasons. The mean dose was 9.92 micrograms/kg bodyweight during the first season and 10.22 micrograms/kg during the second. Naloxone hydrochloride was used as the antagonist, averaging 0.53 mg/kg and 1.73 mg/kg over the two periods although the latter is probably unnecessarily high. Ketamine and xylazine at a ratio of 5:1 were also used during the same two seasons, 57 seals being anaesthetised on 104 occasions. The average dose of ketamine was 4.96 mg/kg and 5.15 mg/kg with xylazine in proportion. Complications arose on a number of occasions and these are discussed.

Animals↗
PubMed1985

Serum fructosamine concentration as measure of blood glucose control in type I (insulin dependent) diabetes mellitus.

Serum fructosamine activity was studied in 42 patients with type I (insulin dependent) diabetes mellitus and 30 non-diabetic volunteers as an index of blood glucose control. There was a significant correlation both between fructosamine and glycosylated haemoglobin values (r = 0.82) and between fructosamine and the fasting C peptide concentration (r = -0.81). Test results in 14 of the diabetics reflected the mean plasma glucose concentration calculated from 25 serial estimations in a single 24 hour period (r = 0.75; p less than 0.01) but not the mean amplitude of glycaemic excursion (r = 0.23; p greater than 0.05). Fructosamine concentrations measured in these multiple blood specimens did not change significantly throughout the day (mean coefficient of variation 4.1%) despite wide variability of the respective plasma glucose concentrations (mean coefficient of variation 36.2%). It is concluded that a single random serum sample analysed for fructosamine concentration provides a simple and reliable assessment of glucose homoeostasis in patients with type I diabetes mellitus.

Adolescent↗