Showing papers by "DeWitt S. Goodman published in 1985"
TL;DR: The data suggest thattransthyretin in the brain and the cerebrospinal fluid results from de novo synthesis and that transt Hyretin may play a significant physiological function, as yet unknown, within the nervous system.
238 citations
TL;DR: Both parenchymal and stellate cells contain substantial amounts of retinoids and of the enzymes and intracellular binding proteins involved in retinol metabolism, and stelate cells are particularly enriched in these several components.
198 citations
TL;DR: The large and abundant parenchymal cells account for greater than 70% of the liver's RBP, RPH, CRBP, and CRABP; but the much smaller and less abundant fat-storing cells contain the majority of hepatic retinoids and greatly enriched concentrations of RPH and CRBP.
157 citations
TL;DR: CRBP metabolism and levels appear to be minimally influenced by the amount or kind of retinoid ligand available or by sex, while CRABP levels showed no diet- or sex-dependent differences.
142 citations
TL;DR: Several studies strongly suggest that the presence of TTR(Met30) in plasma constitutes a predictive biochemical marker of FAP in the preclinical phase of the disease.
Abstract: A transthyretin variant with a methionine for valine substitution at position 30 [TTR(Met30)] is found in Portuguese patients with familial amyloidotic polyneuropathy (FAP). Effective, rapid, small- and semimicro-scale (immunoblotting) procedures were developed to determine whether or not TTR(Met30) is present in the plasma of an individual subject. The immunoblotting procedure employs only 0.10 ml of serum and can serve as a reliable procedure for the screening of large numbers of persons for the presence of TTR(Met30). In family studies of seven FAP kindreds, TTR(Met30) was found in 21 out of 41 asymptomatic FAP offspring, and its presence was not related to either age or sex. Thus, the mutant TTR segregated in accordance with the known autosomal dominant mode of inheritance of FAP. Total plasma TTR levels were not reduced in asymptomatic FAP offspring who were carriers of TTR(Met30), and no difference was observed between carriers and noncarriers of the mutant TTR. The ratios of the variant to normal TTR in plasma were estimated in asymptomatic FAP offspring and were similar to those found in FAP patients. In contrast, TTR(Met30) was relatively enriched in cerebrospinal fluid samples from two FAP patients. The significance of this finding is not known, but might relate to the preferential deposition of amyloid in the nervous system in FAP. A limited study was conducted involving simultaneous analysis of both stored (collected in 1975) and fresh serum from 20 FAP offspring, all of whom had been asymptomatic in 1975. In every subject, the results obtained with the stored and the fresh serum samples were in agreement. Six of these subjects developed clinical FAP since 1975; TTR(Met30) was present in each of these subjects. These several studies strongly suggest that the presence of TTR(Met30) in plasma constitutes a predictive biochemical marker of FAP in the preclinical phase of the disease.
117 citations
TL;DR: These studies on the localization of CRBP provide information concerning the specific cells and anatomic loci within the testis and epididymis where retinol may be playing an important role in sperm formation and maturation.
Abstract: The immunohistochemical localizationof cellularretinol-bindingprotein (CRBP) was studied in rat testis and epididymis. Parallel studies were also carried out on the localization of plasma retinolbinding protein (RBP) and transthyretin (TTR) in testis. The studies employed antibodies purified by immunosorbent affinity chromatography, permitting the specific staining and localization of each antigen by the unlabeled peroxidase-antiperoxidase method. For RBP and TTR, specific immune staining was found in the interstitial spaces between the seminiferous tubules, and not in the tubules themselves. In contrast, strong specific immune staining for CRBP was found in the seminiferous tubules, with a striking localization within Sertoli cells. Moreover, a distinct cyclic variation of specific staining for CRBP within Sertoli cells was observed during the spermatogenic cycle. This cyclic variation was seen with regard to both the intensity of stainingand to the anatomic distribution of CRBP within the Sertoli cells. Within the epididymis CRBP was selectively localized to the proximal portion of the caput epididymidis, with variations in intensity of the staining of the epithelium of the ducts in different histological zones. Specific immune staining for CRBP was very weak or absent in the other portions of the epididymis. These results were confirmed by radioimmunoassay. Vitamin A-deficient rats showed markedly reduced specific immune staining for CRBP in both testes and epididymides, and greatly reduced levels of CR3? in these tissues on radioimmunoassay. These studies on the localization of CRBP provide information concerning the specificcells and anatomic loci within the testis and epididymis where retinol may be playing an important role in sperm formation and maturation.
84 citations
TL;DR: The findings suggest that retinoids and their binding proteins may play important metabolic roles within islet cells, and hence that they may be involved in some way in the biological, endocrine, function of the islets.
Abstract: The immunohistochemical localization of plasma retinol-binding protein (RBP), cellular retinol-binding protein (CRBP), and transthyretin (TTR) was studied in rat pancreas. The studies employed antibodies purified by immunosorbent affinity chromatography, permitting the specific staining and localization of each antigen by the unlabeled peroxidase-antiperoxidase method. Specific immunostaining for each of these three proteins was found localized to the islets of Langerhans. Both RBP and CRBP were localized in cells that were peripherally distributed within the islets, with an anatomic distribution that resembled that of the glucagon-containing A cells. Immunoreactive TTR was localized in cells that were more centrally distributed in the islets, with an anatomic distribution that resembled that of the insulin-containing B cells. These findings were confirmed by radioimmunoassay of a homogenate of isolated rat islets. By using sensitive and specific radioimmunoassays for each antigen, unusually high levels of CRBP, RBP, TTR, and cellular retinoic acid-binding protein (CRABP) were found in rat islets. The physiological significance of the localization of RBP, CRBP, CRABP, and TTR in the islets is not known. The findings suggest that retinoids and their binding proteins may play important metabolic roles within islet cells, and hence that they may be involved in some way in the biological, endocrine, function of the islets.
63 citations
TL;DR: The patterns of distribution of RBP and RPH activity observed in the liver sections from both vitamin A-sufficient and deficient rats were not significantly correlated, either directly or inversely as determined by chi-square analysis.
Abstract: A study was conducted to explore the spatial distribution within rat liver of two proteins importantly involved in retinoid metabolism in liver, namely, retinol-binding protein (RBP) and the enzyme retinyl palmitate hydrolase (RPH). The study was conducted with both vitamin A-sufficient (control) and vitamin A-deficient rats. Livers were carefully and reproducibly dissected into 11 sections each, and RBP levels and RPH activities were measured for each section homogenate. Both RBP and RPH activity displayed highly significant spatial heterogeneity in their distributions in liver. For control rats, the mean level of RBP was 39.0 micrograms/g wet weight, with a section-to-section variation of 14.5. For deficient rats, the corresponding RBP mean and variation values were 283 and 56 micrograms/g wet weight. For RPH, the mean level was 136 pmol free fatty acids (FFA) formed/(min X mg) with a section-to-section variation of 178. Both inspection of the data and analysis of variance indicated that this significant section-to-section variation (spatial heterogeneity) did not follow a consistent anatomic pattern from rat to rat. Thus, no one specific anatomic location in the liver was consistently high or low with regard to either RBP or RPH. Since the spatial distributions of both RBP and RPH activity did not follow a consistent anatomic pattern, it is not possible to obtain an accurate measure of the total liver levels for either parameter in a homogenate made from a small section. Finally, the patterns of distribution of RBP and RPH activity observed in the liver sections from both vitamin A-sufficient and deficient rats were not significantly correlated, either directly or inversely, as determined by chi-square analysis. Thus, RBP and RPH activity levels vary independently of each other in their heterogeneous anatomic distributions in rat liver.
27 citations
TL;DR: It is concluded that plasma levels of HDL cholesterol and apoproteins A-I, A-II, and E are not quantitatively important independent determinants of the mass of slowly exchanging body cholesterol or of other parameters of long-term cholesterol turnover in humans.
23 citations
TL;DR: The finding that the measured total body cholesterol fell within the range obtained from the kinetic analysis by using reasonable assumptions, provides evidence for the physiological validity of the pool model.
16 citations
TL;DR: These findings suggest that as part of a cell’s response to a mitogenic stimulus, it can increase its ability to obtain cholesterol via both exogenous and endogenous means.
Abstract: Focal proliferation of cells in the arterial intima is a prominent feature of atherogenesis and contributes to the production of the atherosclerotic plaque.’ Much of what we know about the molecular mechanisms that regulate cellular proliferation has been determined by studying cells in culture. Proliferation of normal diploid cells in culture (and presumably, in vivo) is known to be under the control of exogenous growth factors.’** These include platelet-derived growth factor (PDGF)34 epidermal growth factor (EGF),’ and the insulin-like growth factors6 It has become well established that these polypeptide growth factors initiate their effects on cells by binding to highaffinity, specific, cell-surface receptors. Although numerous cellular events are known to occur after the stimulation of a cell by a mitogen, the detailed molecular mechanisms whereby the interaction of a growth factor with its receptor leads to later DNA synthesis remain a mystery. A recent paper by Mroczkowski et al.’ presented intriguing data suggesting that the receptor itself may function as a “second messenger.” Thus, these workers reported that purified EGF receptors had endonuclease activity that could nick double-stranded circular DNA and convert it to a relaxed form. However, evidence has also been accumulating over the past several years that it may be the activation of a pathway involving polyphosphoinositidederived “second that are responsible for the series of events leading to DNA synthesis. Among the cellular events which occur in response to a mitogenic stimulus are those involving cholesterol synthesis and metabolism. For example, in earlier studies from this laboratory, parallel increases in both DNA synthesis and in the number of low-density lipoprotein (LDL) receptors per cell were found following the treatment of quiescent human fibroblasts with PDGF.“ In addition, rapidly proliferating cells and tissues have been reported to show a high rate of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity.’* This enzyme converts HMG-CoA to mevalonic acid, which is usually the rate-limiting reaction of cholesterol biosynthesis.” These findings suggest that as part of a cell’s response to a mitogenic stimulus, it can increase its ability to obtain cholesterol via both exogenous and endogenous means. Inhibition of a cell’s ability to obtain cholesterol has been shown to prevent cell
TL;DR: The results suggest that an intact cyclohexene ring may be necessary for the stimulation of RBP secretion, whereas the system did not exhibit much specificity with regard to either the structure of the side chain or the nature of the end group.
TL;DR: Results indicated that the sites of attachment of IEBA to RBP are located inside the region of the RBP molecule close to the Cys-4–Cys-160 bond, and specifically within the region comprised of amino acid residues 1–5 and 156–163.
Abstract: The retinoid affinity label 11[3H]-β-ionylidene ethylbromoacetate (IEBA) was covalently bound to plasma retinol-binding protein (RBP) and studies were conducted to identify the region of the protein molecule that contained the linkage between the IEBA ligand and RBP. Cleavage by trypsin and cyanogen bromide of the labeled protein followed by high-performance liquid chromatography (HPLC) separation of peptides and identification of radioactive peaks by amino acid analysis points to attachment of the ligand on tryptic peptides T(1+2) (containing residues 1–5) and T(21) (residues 156–163). These two peptides in the native protein molecule are connected by a disulfide bond between Cys-4 and Cys-160. To confirm the site of attachment of the radioactive ligand, unreduced IEBA-RBP with the disulfide bonds intact was treated first with cyanogen bromide and then with trypsin. Separation of the tryptic peptides by HPLC yielded one main peak of radioactivity containing both peptides T(1+2) and T(21), presumably connected by a disulfide bond. Taken together, these results indicated that the sites of attachment of IEBA to RBP are located within the region of the RBP molecule close to the Cys-4–Cys-160 bond, and specifically within the region comprised of amino acid residues 1–5 and 156–163.
TL;DR: The simplified six-point schedule makes it feasible to study long-term cholesterol turnover in substantial numbers of patients and compared parameter estimates obtained with those obtained simultaneously (in the same, single turnover study) by the old 36- point schedule in the same 26 subjects.
TL;DR: Analysis of FAP patients with familial amyloidotic polyneuropathy who are carriers of an abnormal transthyretin- TTR indicated that TTR appears to constitute a direct and true genetic marker of the disease.
Abstract: Studies were conducted in Portuguese patients with familial amyloidotic polyneuropathy (FAP) who are carriers of an abnormal transthyretin- TTR(Met 30 ). Two FAP kindreds were screened for the presence of TTR(Met 30 ) by both protein analysis and by the use of TTR cDNA. These analyses indicated that TTR(Met 30 ) appears to constitute a direct and true genetic marker of the disease.