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Biomedical subjects

T Taylor

Publications and source records attributed to T Taylor.

At least 127 records · Page 7Linked to original sources
PubMed1989

The fetal rat binding protein for insulin-like growth factors is expressed in the choroid plexus and cerebrospinal fluid of adult rats.

The biological effects of the insulin-like growth factors, IGF-I and IGF-II, on their receptors are modulated by IGF-binding proteins. Recently, we isolated a cDNA clone for one member of the family of IGF-binding proteins, BP-3A, a 30 kilodalton (kDa) protein synthesized by the BRL-3A rat liver cell line. BP-3A is related to but distinct from two other cloned IGF-binding proteins, the human amniotic fluid binding protein and the glycosylated binding subunit of the 150 kDa IGF-binding protein complex in serum. It is expressed in multiple nonneural tissues and in serum in the fetal rat and decreases after birth, similar to the developmental pattern of IGF-II expression. IGF-I, IGF-II, and their receptors are expressed in brain. The present study examines the expression of BP-3A in the rat central nervous system. By Northern blot analysis, BP-3A mRNA is present at high levels in brain stem, cerebral cortex, and hypothalamus from 21-day gestation rats and, like IGF-II mRNA, persists in adult rat brain. The site of BP-3A mRNA synthesis was localized by in situ hybridization to coronal sections of adult rat brain using 35S-labeled oligonucleotides, 48 bases in length, complementary and anticomplementary to the coding region of BP-3A. Specific hybridization of the BP-3A probe was observed exclusively to the choroid plexus extending from the level of the medial preoptic nucleus to the arcuate nucleus of the hypothalamus, similar to the previously reported preferential localization of IGF-II mRNA to the choroid plexus. Synthesis of BP-3A mRNA by choroid plexus suggested that BP-3A might be secreted into the cerebrospinal fluid. A 30 kDa IGF-binding protein was demonstrated in rat cerebrospinal fluid that is recognized by antibodies to BP-3A and, like purified BP-3A, has equal affinity for IGF-I and IGF-II. By analogy with other transport proteins synthesized by the choroid plexus, BP-3A may facilitate the secretion of IGF-II to the cerebrospinal fluid and modulate its biological actions at distant sites within the brain.

Animals↗
PubMed1989

Absorption of amlodipine unaffected by food. Solid dose equivalent to solution dose.

The oral bioavailability of amlodipine in healthy volunteers was compared in two separate studies after solution and capsule doses, and after capsule doses in fed and fasting states. The bioavailability of amlodipine was equivalent both in terms of rate and in extent of absorption between solution and capsule doses and in the fed and fasting states.

Adult↗
PubMed1989

Multiple forms of pancreatic polypeptide-related compounds in the lamprey CNS: partial characterization and immunohistochemical localization in the brain stem and spinal cord.

Although neuropeptide Y (NPY) is established as a transmitter in many regions of the nervous system, the role of other peptides of the pancreatic polypeptide (PP) family in the CNS is obscure. This study provides evidence that PP-like peptides in the "primitive" CNS of a cyclostome are composed of different molecular forms, which are stored in separate neuronal populations with apparently different functions. PP-like material was detected in extracts of brain and spinal cord from Lampetra fluviatilis by radioimmunoassay (RIA) using an antiserum to the C-terminal hexapeptide of mammalian PP. The PP-immunoreactive material consisted of several molecular forms, as shown by its complex elution profile on high-performance liquid chromatography (HPLC). The cellular distribution of PP-like immunoreactivity was studied with indirect immunofluorescence histochemistry using antisera toward porcine peptide YY (PYY), porcine neuropeptide Y (NPY), and bovine (BPP), rat (RPP), and avian (APP) pancreatic polypeptide. Adjacent sections from the brain stem and spinal cord of L. fluviatilis and Ichthyomyzon unicuspis, incubated with the different antisera, displayed 2 main patterns of PP immunoreactivity. The PYY and RPP antisera labeled groups of neurons and fibers in the rhombencephalic and mesencephalic reticular formation. One of the PYY/RPP-ir cell groups, located in the anterior rhombencephalic reticular nucleus, had a projection to the dorsolateral spinal cord. Fibers of this reticulospinal system were in close apposition to dendrites of intracellularly stained spinal motoneurons and sensory relay interneurons, indicating that they may receive PPergic input. In contrast, antisera to NPY and APP labeled local neurons systems in the spinal dorsal horn, in the lateral parts of the brain stem, including the rhombencephalic alar plate, and in the retina. The BPP antiserum recognized the NPY/APP as well as the PYY/RPP immunoreactive neuron systems, further supporting that they both contain PP-like peptides.

Animals↗
PubMed1988

Comparison of the mouse spleen cell assay and a radioimmunoassay for the measurement of serum erythropoietin.

The mouse spleen cell assay (MSCA) has been compared with a radioimmunoassay for the measurement of serum erythropoietin (Ep). In 20 normal subjects the serum values ranged from 15 to 73 mU/ml for the MSCA compared with 5-30 mU/ml for the RIA. For normal sera there was no correlation between the results of the two assays. In 37 patients with anaemias of differing aetiologies and at various stages of treatment values ranged from 10 to 3645 mU/ml for the MSCA and 13-10,000 mU/ml for the RIA. Although patient values from the two assays were highly correlated (r = 0.98, P less than 0.001), the MSCA results were generally lower. These discrepancies can be largely accounted for by two factors. Firstly the MSCA is sensitive to non-specific matrix effects. Secondly, heat inactivation of serum, a prerequisite for the MSCA, but not for the RIA, destroys a variable and unpredictable proportion of the Ep in the test sera leading to an underestimation of Ep in the MSCA. We conclude that the RIA is more reliable than the MSCA which, in its present form, cannot be recommended for the accurate measurement of serum erythropoietin.

Anemia↗
PubMed1988

Measurement of theophylline in dried blood spots by spectrophotometric enzyme immunoassay.

A widely-used enzyme immunoassay for the measurement of theophylline in plasma (EMIT) has been adapted for use with dried blood spots. Potential interference from haemoglobin in eluates of the spots was avoided by autoclaving them prior to analysis. The method was investigated in terms of the recovery of theophylline added to samples, precision, and the correlation of results in DBS with those in plasma samples. The recoveries of some other drugs from eluates of autoclaved DBS were also investigated.

Adolescent↗
PubMed1988

Hypothalamic hypothyroidism caused by lesions in rat paraventricular nuclei alters the carbohydrate structure of secreted thyrotropin.

The effects of hypothalamic hypothyroidism vs. primary hypothyroidism on TSH carbohydrate structure were studied in the rat. Adult male rats with bilateral paraventricular nuclear lesions (n = 10), sham lesions (n = 10), and thyroidectomies (n = 6) were studied 2 weeks postoperatively and compared to normal animals without surgery (n = 6). Pituitaries were incubated in medium containing [3H]glucosamine for 24 h. TSH was immunoprecipitated from medium and pituitary sonicates using anti-TSH beta serum, digested with pronase to obtain TSH glycopeptides, desalted, then analyzed by Concanavalin-A (Con-A) chromatography. Compared to sham controls, hypothalamus-lesioned animals contained a greater proportion of secreted TSH glycopeptides that bound weakly to Con-A, indicating a shift from bisecting and/or multiantennary structures in control animals to biantennary and/or truncated hybrid forms in hypothalamus-lesioned animals. In contrast, thyroidectomized animals, compared to normal and lesioned animals, contained a greater proportion of secreted TSH glycopeptides that did not bind to Con-A, indicating a shift from biantennary and/or truncated hybrid forms to bisecting and/or multiantennary forms. The characteristics of the carbohydrate chains on secreted TSH differed markedly in hypothalamic vs. primary hypothyroidism despite equally low thyroid hormone levels in vivo. Thus, in addition to regulating TSH secretion, hypothalamic hormones alter TSH carbohydrate structure, which may affect its bioactivity and MCR.

Animals↗
PubMed1987

Modulation of testicular galactolipid sulfotransferase activity in vitro by ATP.

Testicular galactolipid sulfotransferase activity is an early marker of differentiation during mammalian spermatogenesis. The enzyme will catalyze the sulfation of galactosylglycerol in the 3' position of the galactose moiety at 37 degrees C in vitro. However, sulfotransferase activity was found to be completely lost on preincubation of the solubilized enzyme preparation at 37 degrees C. This loss of activity was completely prevented by inclusion of ATP and Triton in the preincubation step. This protective effect was synergistic, pH dependent and correlated with an inhibition of endogenous phosphatase activity. These results are interpreted to suggest that the galactolipid sulfotransferase may be regulated by a phosphorylation mechanism.

Adenosine Triphosphate↗
PubMed1987

Systemic administration of glycosaminoglycan polysulphate (arteparon) provides partial protection of articular cartilage from damage produced by meniscectomy in the canine.

Bilateral medial meniscectomy was undertaken in 14 mature beagles. Another two underwent arthrotomy (sham-operated controls). One week after surgery, six of the meniscectomised animals were administered glycosaminoglycan polysulphate (Arteparon) (2 mg/kg) subcutaneously three times a week for 3 weeks, then twice weekly until killed 23 weeks later. Two months before death all animals were given Na2(35)SO4 (1.0 mCi/kg) intravenously. At autopsy, articular cartilage (AC) from the medial and lateral compartments, as well as from the femoral trochlear groove and femoral head, was sampled. Proteoglycans (PGs) were isolated by 4.0 M Guanidine hydrochloride (GuHCl) extraction of AC and purified by ultracentrifugation. The PG monomers were assayed for hexuronic acid, protein, and hexosamines (galactosamine/glucosamine), and their ability to aggregate. The results indicated that Arteparon provided some protective effect to AC in the meniscectomised compartment as demonstrated histologically by reduced surface fibrillation, diminished chondrocyte cloning, and maintenance of alcianophilia. The levels of PGs and hexuronate-protein ratios in medial AC of drug-treated meniscectomised animals were found to be comparable to sham controls, whereas these parameters in the nondrug-treated meniscectomized group were depressed.

Animals↗
PubMed1987

Changes in thyrotropin (TSH) carbohydrate structure and response to TSH-releasing hormone during postnatal ontogeny: analysis by concanavalin-A chromatography.

We have studied the carbohydrate structure of TSH as well as its response to TRH during postnatal ontogenesis in the rat using Concanavalin-A (Con A)-Sepharose chromatography of labeled glycopeptides. Pituitaries from neonatal (5-day-old) rats with low levels of endogenous TRH and mature (56-day-old) rats were incubated for 24 h in medium containing [3H] glucosamine in the presence or absence of 10(-7) M TRH. Both intracellular and secreted TSH were immunoprecipitated, treated with Pronase to generate glycopeptides, and analyzed by chromatography on Con A-Sepharose. The total amount of [3H]glucosamine-labeled TSH was greater per pituitary in mature rats compared to that in neonatal rats (P less than 0.05), while there was no significant difference between the groups in the concentration of total labeled TSH per microgram pituitary DNA. RIA determination of total TSH was greater in the older animals than in the younger animals when normalized both per pituitary and per microgram pituitary DNA (P less than 0.01 and P less than 0.02, respectively). However, for both labeled and unlabeled TSH the percentage of TSH secreted was greater in mature rats than in neonatal rats (P less than 0.02 and P less than 0.01, respectively), indicating a less active hormonal secretory process in the younger animals. In control animals, the proportion of labeled TSH glycopeptides that did not bind to Con A was greater in 56- than in 5-day-old animals for both intrapituitary and secreted forms (P less than 0.01), reflecting a shift toward more multiantennary and/or bisected biantennary complex carbohydrate structures in the older animals. In response to TRH in vitro, the total amount of labeled secreted TSH was increased more than 2-fold in both 5-day-old (P less than 0.05) and 56-day-old (P = NS) animals. However, there was a marked difference in the glycopeptide distribution between these two ages. Five-day-old animals showed a small but not significant decrease in the percentage of secreted TSH glycopeptides that bound to Con A-Sepharose, while 56-day-old animals had a specific increase in the glycopeptide fractions that bound and corresponded to biantennary complex and/or unusual hybrid forms (P less than 0.01). These studies in the rat suggest differences in TSH carbohydrate structure and secretion as well as a differential response to TRH during postnatal ontogenesis.

Aging↗
PubMed1987

Customers versus patients. A marketing perspective on health care.

The thrust of health care "solutions" in the press and in Congress focus on the infirm. In fact, it is the only segment where all of the various economic models fit well. Considerable marketing planning and implementation techniques must be brought to bear on solutions for the healthy, the worried, and the early sick segments in the near future.

Economic Competition↗
PubMed1986

High-performance liquid chromatographic fractionation and partial characterization of cystic fibrosis serum ultrafiltrates.

Analytical separation of serum ultrafiltrates by high-performance liquid chromatography produces a distinctive peak with a retention time of 18.5-21 min (subfraction 18.5) from cystic fibrosis serum ultrafiltrates and obligate heterozygote serum ultrafiltrates, but not in significant concentrations from control or asthmatic serum ultrafiltrates. Semipreparative separation of control serum ultrafiltrates produced a small peak with similar retention time that was approximately 1% of the arbitrary absorbance units found in this cystic fibrosis subfraction. Subfraction 18.5 had biological activity only when separated from cystic fibrosis serum ultrafiltrate, but did not contain measurable amounts of C3a des-arginine and C4a des-arginine. Subfraction 18.5 is a low-molecular-weight material (1000-1400 daltons) that contains 14.9 micrograms orcinol positive material per 50 micrograms protein. The spectrum of subfraction 18.5 indicates that it has to be purified to homogeneity.

Carbohydrates↗
PubMed1986

Regulation of renal sulfoglycolipid biosynthesis.

The in vitro activity of the renal galactolipid sulfotransferase and the level of sulfated glycolipids in the rat kidney have been correlated as a function of age. The galactolipid sulfotransferase was found to be greatly reduced in the young as compared with the adult animal. The relatively minor changes in the sulfated glycolipid content of the kidney with age suggests that an increase in sulfoglycolipid turnover occurs during growth. An inhibitory activity was detected in the homogenate supernate of the young animal capable of reducing the in vitro sulfotransferase activity of the adult. Assay of the human renal galactolipid sulfotransferase showed that this enzyme activity is deleted in samples of the blastematous form of Wilm's renal tumor. The results suggest that the rate of synthesis of renal sulfoglycolipids may prove a marker of renal development, perhaps by post translational regulation.

Aging↗
PubMed1986

Effects of in vivo bolus versus continuous TRH administration on TSH secretion, biosynthesis, and glycosylation in normal and hypothyroid rats.

The effects of in vivo TRH administered either as bolus or continuous doses on TSH secretion, synthesis, and glycosylation were studied in normal and hypothyroid rats. Nine-week-old normal or 3-week postthyroidectomy rats were administered bolus doses of saline or TRH (0.5 mg/kg) twice daily or continuous saline or TRH (1 mg/kg/day) via an osmotic pump. After 5 days, pituitaries were removed and incubated with [35S]methionine (MET) and [3H]glucosamine (GLCN), with or without 10(-8) M TRH, for 6 and 24 h. Samples were precipitated with anti-TSH beta sera and then analyzed by gel electrophoresis. In normal rats, plasma TSH, T4 and T3 increased with continuous in vivo TRH but not with bolus TRH; in hypothyroid rats, plasma TSH, T4 and T3 were not altered by continuous or bolus doses of TRH. Additionally, in normal rats, continuous in vivo TRH increased incorporation of MET in secreted TSH (477 vs. 212 X 10(3) dpm/mg DNA; P less than 0.05) and intrapituitary TSH (5035 vs. 2124 X 10(3) dpm/mg DNA; P less than 0.05), and GLCN in secreted TSH (148 vs. 50 dpm/mg DNA; P less than 0.05) and intrapituitary TSH (2344 vs. 744 X 10(3) dpm/mg DNA; P less than 0.05). In contrast, in hypothyroid animals, continuous in vivo TRH did not alter MET or GLCN incorporation in TSH. Bolus TRH did not alter secreted or intrapituitary MET or GLCN incorporation into TSH in the normal rat. However, bolus TRH in the intrapituitary MET or GLCN incorporation into TSH in the normal rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Synthesis and use of galactolipid sulfotransferase substrate-analogue affinity probes: possible localization of the testicular enzyme.

Galactosyl ceramide (GC) is a substrate in vitro for galactolipid sulfotransferase preparations from brain, kidney, and testis. Biotinylated and light-sensitive azido derivatives of lysogalactosyl ceramide have been synthesized. These derivatives remain effective substrates for the testicular enzyme. Biotinylated GC has been used to localize specific GC-binding sites in frozen sections of rat testis. The binding pattern is consistent with the expected location of the testicular galactolipid sulfotransferase.

Affinity Labels↗