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D J Klein

Publications and source records attributed to D J Klein.

At least 55 records · Page 3Linked to original sources
PubMed1988

Glomerular basement membrane proteoglycans are derived from a large precursor.

The basement membrane heparan sulfate proteoglycan produced by the Englebreth-Holm-Swarm (EHS) tumor and by glomeruli were compared by immunological methods. Antibodies to the EHS proteoglycan immunoprecipitated a single precursor protein (Mr = 400,000) from [35S]methionine-pulsed glomeruli, the same size produced by EHS cells. These antibodies detected both heparan sulfate proteoglycans and glycoproteins in extracts of unlabeled glomeruli and glomerular basement membrane. The proteoglycans contained core proteins of varying size (Mr = 150,000 to 400,000) with a Mr = 250,000 species being predominant. The glycoproteins are fragments of the core protein which lack heparan sulfate side chains. Antibodies to glomerular basement membrane proteoglycan immunoprecipitated the precursor protein (Mr = 400,000) synthesized by EHS cells and also reacted with most of the proteolytic fragments of the EHS proteoglycan. This antibody did not, however, react with the P44 fragment, a peptide situated at one end of the EHS proteoglycan core protein. These data suggest that the glomerular basement membrane proteoglycan is synthesized from a large precursor protein which undergoes specific proteolytic processing.

Animals↗
PubMed1987

Proteoglycan metabolism associated with mouse metanephric development: morphologic and biochemical effects of beta-D-xyloside.

Morphology and de novo incorporation of [35S]sulfate into proteoglycans were studied in fetal mouse kidneys at the onset of organogenesis. Branching morphogenesis and nephron development in organ culture and in vivo were associated with de novo synthesis of chondroitin-SO4 and heparan-SO4 proteoglycans. The role of proteoglycan metabolism in metanephrogenesis was then studied by analysis of the effects of p-nitrophenyl-beta-D-xylopyranoside (beta-D-xyloside) on renal development and proteoglycan metabolism. Incubation of fetal kidneys in beta-D-xyloside at concentrations of 1.0 and 0.5 mM, but not at 0.1 mM, caused inhibition of ureteric branching and markedly diminished synthesis of a large Mr 2.0 X 10(6) Da chondroitin-SO4 proteoglycan. Incorporation of [35S]sulfate was stimulated at all beta-D-xyloside concentrations, reflecting synthesis of xyloside initiated dermatan-35SO4 chains. In contrast to dramatic effects on chondroitin-SO4 synthesis and ureteric branching, beta-D-xyloside had no effect on heparan-SO4 synthesis or on development of the glomerulus and glomerular basement membrane. We thus characterize the proteoglycans synthesized early in the course of renal organogenesis and describe observations which suggest an association between metabolism of chondroitin-SO4 proteoglycan and development of the ureter.

Animals↗
PubMed1986

Partial characterization of heparan and dermatan sulfate proteoglycans synthesized by normal rat glomeruli.

Rat glomerular heparan sulfate (HS) and dermatan sulfate (DS) proteoglycan synthesis was studied in vitro and in vivo. Incorporation of [35S]sulfate into macromolecules was linear over 16 h in vitro, and DS was the predominant glycosaminoglycan (GAG), while HS dominated in vivo incubations. Proteoglycans were found in the bottom 2/5 (high density) CsCl gradient fractions and eluted as two overlapping peaks from DEAE-Sephacel columns. The proportion of low density 35S-glycoproteins and 35S-proteoglycans increased with time. Two high buoyant density HS proteoglycans were extracted from glomeruli and eluted in DEAE peak I. The first, HS-tIA, had an Mr of 130 X 10(3) with Mr 12.5 X 10(3) GAG chains. This proteoglycan was released from the tissue by trypsin and was partially displaced by heparin treatment. In addition, it was rapidly released into the medium of label-chase experiments after which it migrated slightly more rapidly than HS-tIA in gels, with HS chains similar in length to its tissue counterpart. The second, HS-tIB, had an Mr of 8.6 X 10(3) with little or no attached protein. This proteoglycan was characterized as intracellular as it resisted release by trypsin treatment or heparin extraction in medium and was not detected in the medium of label-chase experiments. Two tissue DS proteoglycans were characterized. The first, DS-tIA, co-purified with HS-tIA and was the predominant proteoglycan synthesized during 4-h in vitro incubations. Like HS-tIA, it was rapidly released into medium and displaced from cell surfaces or tissue "receptors" by heparin or trypsin treatments. A second, Sepharose CL-6B-excluded DS proteoglycan from DEAE peak II, DS-tII, accumulated in tissue over 16 h in vitro. This proteoglycan was self-associating and contained clusters of iduronic acid residues along its Mr 26 X 10(3) DS chains. It resisted extraction from the tissue with heparin, trypsin, and detergent. No DS-tII was detected in the incubation medium. Instead, medium proteoglycans eluted as single Sepharose CL-6B-included peaks. DS chains from medium proteoglycans were shorter (Mr 18 X 10(3)) and had more regularly spaced iduronic acid residues than GAGs from DS-tII. The length and sulfation patterns of DS-mII GAG were similar to GAG from DS-tIA. Thus, glomeruli rapidly synthesized and released Sepharose CL-6B-included heparin-displaceable DS and HS proteoglycans while retaining a Sepharose CL-6B-excluded self-associating DS proteoglycan and an intracellular HS.

Animals↗
PubMed1986

Glomerular proteoglycans in diabetes. Partial structural characterization and metabolism of de novo synthesized heparan-35SO4 and dermatan-35SO4 proteoglycans in streptozocin-induced diabetic rats.

The metabolism of glomerular proteoglycans was studied in an effort to understand the mechanisms leading to reduction of glomerular basement membrane (GBM) heparan sulfate (heparan-SO4) proteoglycan in diabetes. Glomeruli were isolated from control and streptozocin-induced diabetic rats after exposure to [35S]sulfate. A pool of rapidly metabolized 35S-glycosaminoglycans (GAG), predominantly heparan-35SO4, was present in GBMs from controls but not diabetics, whereas intact isolated glomeruli from the two groups contained similar quantities of 35S-macromolecules after 4 and 16 h in vitro. Glomeruli from diabetics contained less 35S-proteoglycan than controls after 16 h in vivo. A more rapid disappearance of [35S]sulfate from serum and an increased inorganic sulfate concentration in diabetes may account for this difference. Glomeruli from diabetics contained more heparan-35SO4 and less dermatan-35SO4 proteoglycan than control glomeruli in vitro. Diabetic glomerular heparan-35SO4 proteoglycan and its GAG chains had hydrodynamic sizes similar to controls (Mr, 13 and 1.25 X 10(4), respectively). A heparin-releasable heparan-35SO4 proteoglycan detected in isolated control glomeruli by gel electrophoresis was present in chase medium of glomeruli from diabetics in the absence of heparin. Two dermatan-35SO4 proteoglycans were synthesized in vitro. One had size and charge properties similar to glomerular heparan-35SO4 proteoglycan. A second, larger dermatan-35SO4 proteoglycan accumulated in tissue over 16 h. It was partially excluded from Sepharose CL-6B columns and eluted from Sepharose CL-4B columns at Kav = 0.32. The hydrodynamic sizes of both tissue forms of dermatan-35SO4 proteoglycans were similar in diabetics and controls. Differences in the biochemical characteristics of the major de novo synthesized glomerular proteoglycan pools could not be invoked to explain altered metabolism of GBM heparan sulfate in diabetic animals. These changes may result from diminished affinity of heparan sulfate proteoglycan for extracellular matrix or cell surfaces and may account for altered glomerular ultrafiltration properties in diabetes mellitus.

Animals↗
PubMed1984

Alterations in proteoglycan metabolism in the nephrotic syndrome induced by the aminonucleoside of puromycin.

The synthesis of intact proteoglycans and their glycosaminoglycan (GAG) side chains by isolated rat glomeruli in vitro were studied both at the onset (5 days) and at the point of maximal proteinuria (7 days) of the nephrotic syndrome induced with the aminonucleoside of puromycin. Glomeruli from nephrotic animals incorporated 1.5-fold and 3.0-fold more 35SO4 label into GAG than glomeruli from control animals at 5 and 7 days, respectively, with heparan-35SO4 GAG being responsible for the majority of the increment. Both nephrotic and control incubations contained 60% of the label in the incubation medium, 40% in the glomerular fractions, and less than 1% in the glomerular basement membrane. Glomerular basement membrane from nephrotic rats had no change in their total heparan-35SO4 GAG content. The majority of intact proteoglycan(s) from the glomerular matrix and from the incubation medium of nephrotic and control animals was found in the most buoyantly dense fraction of CsCl gradients (fraction 1). 35S-labeled material isolated from glomeruli of nephrotic animals showed a consistent shift toward lower density gradient fractions, indicating a decrease in their overall carbohydrate to protein ratio. Diethylaminoethyl chromatography of fraction 1 proteoglycan showed a single biphasic peak with the nephrotic rat having an increase in the proportion contributed by the earlier component of the peak. Fraction 1 proteoglycan(s) from the nephrotic experiment was found to have a smaller average hydrodynamic size by Sepharose CL-2B chromatography without a significant change in the corresponding 35S-GAG chain sizes (molecular weight 14,000) by Sepharose CL-6B chromatography. 35S-macromolecules from glomeruli of nephrotic and control rats that appeared in the middle of the CsCl gradients (fraction 3) had similar Sepharose CL-2B elution volumes, whereas the corresponding 35S-GAG chains from incubations of glomeruli from nephrotic animals were smaller. Increased synthesis of heparan sulfate proteoglycan by glomeruli from puromycin aminonucleoside-induced nephrotic rats may be compensatory to loss of another component of the glomerular filtration barrier or may result from abnormal interaction of proteoglycan(s) from nephrotic animals with other glomerular matrix constituents.

Animals↗
PubMed1983

Heparan sulfate--rich anionic sites in the human glomerular basement membrane. Decreased concentration in congenital nephrotic syndrome.

Recent work suggests that the normal barrier to penetration of the renal glomerular basement membrane by anionic plasma proteins may depend in part on the existence of negatively charged sites within the membrane. We describe an in vitro cytochemical method for the quantitative demonstration of anionic sites in the normal human glomerular basement membrane. In five normal subjects, ranging in age from 10 days to 57 years, the sites were distributed at regular intervals in the lamina rara externa, with a frequency of 23.8 +/- 6.8 sites per 1000-nm length of membrane. A similar distribution was observed in the basement membranes from three normal human fetuses. Ex vivo perfusion of one cadaver kidney revealed a similar distribution of anionic sites. The number of anionic sites in the glomerular basement membranes of five patients with the congenital nephrotic syndrome was reduced to 8.9 +/- 3.7 (P less than 0.001). Prior incubation of sections of normal kidney in purified heparinase resulted in a marked reduction in the number of anionic sites. We conclude that congenital nephrosis results from failure of heparan sulfate--rich anionic sites to develop in the lamina rara externa of the glomerular basement membrane.

Anions↗
PubMed1983

Self-similar self-avoiding structures: Models for polymers.

The hierarchy of m,n-self-similar self-avoiding structures on a lattice is introduced as a model for linear and branched polymers. The self-similarity condition permits exact solutions that use a generating-function renormalization procedure with full accounting for volume exclusion. Illustrative results are given for the 1,2-linear-chain model and for the 1,2-branched-structure model on a honeycomb lattice. Exponents for the dependence of polymer size on monomer number are obtained for these models, with that for branched structures being independent of the (nonzero) fraction of branch points. Exponents also are found involving branching probability and branching activity; the fact that those quantities are found to be distinct even in the dilute branching limit is a manifestation of the long-range nature of the excluded volume interaction.

Journal Article↗
PubMed1983

Renal localization of heparan sulfate proteoglycan by immunohistochemistry.

Glomerular localization of heparan sulfate proteoglycan (HS-proteoglycan) has been studied immunohistochemically with a highly purified antiserum to bovine aorta HS-proteoglycan core protein. The specificity of the antiserum was enhanced by consecutive fibronectin and chondroitin sulfate-dermatan sulfate proteoglycan (CS-DS proteoglycan) affinity chromatography. The affinity-purified HS-proteoglycan antibody lacked cross-reactivity by enzyme-linked immunosorbent assays (ELISA) with CS-DS proteoglycan, fibronectin, laminin, and Type IV collagen. Reactivity of the antiserum with HS-proteoglycan antigen by ELISA was inhibited by HS core protein derived from CsCl density gradient centrifugation after heparinase treatment of the HS-proteoglycan. Immunofluorescent reactivity of the HS-proteoglycan antiserum was observed with bovine glomerular basement membrane, renal interstitium, Bowman's capsule, renal arterioles, and bovine aorta. No staining was seen with rat, mouse, or human glomeruli.

Animals↗
PubMed1982

35S-glycosaminoglycan and 35S-glycopeptide metabolism by diabetic glomeruli and aorta.

35S-glycosaminoglycan metabolism by glomeruli isolated from streptozotocin-diabetic and control rats was studied in vivo and in vitro. Total 35S-glycosaminoglycan synthesis and retention in the matrix by diabetic glomeruli was reduced while degradation was increased. 35S-glycosaminoglycan content of isolated GBM was similarly decreased. Whereas 35S-glycosaminoglycan content of glomeruli and GBM was decreased after in vitro incubation with 35SO4, a larger proportion of total 35S-glycosaminoglycans was found in the incubation medium from diabetic glomeruli. Both control and diabetic glomeruli synthesize 35S-labeled glycopeptides, the quantity from diabetic glomeruli being reduced. Aorta from 35SO4-injected diabetic rats also synthesized reduced quantities of 35S-glycosaminoglycans. There were no preferential metabolic alterations of species of 35S-glycosaminoglycans by diabetic glomeruli or aortas. These studies suggest that synthesis of 35S-glycosaminoglycans and 35S-glycopeptides by diabetic glomeruli are altered by disturbances of both synthetic as well as degradative pathways. An alteration of 35S-glycosaminoglycans interaction with matrix components in diabetes is postulated.

Animals↗
PubMed1979

Self-avoiding random walks on lattice strips.

A self-avoiding walk on an infinitely long lattice strip of finite width will asymptotically exhibit an end-to-end separation proportional to the number of steps. A proof of this proposition is presented together with comments concerning an earlier attempt to deal with the matter. In addition, some unproved, yet "obvious," conjectures concerning self-avoiding walks are cited as basic propositions requiring study.

Journal Article↗
PubMed1977

Blindness in a patient with malignant histiocytosis.

Malignant histiocytosis (MH) is a rapidly fatal systemic disease for which there is no adequate therapy. A case of MH with involvement of both eyes resulting in bilateral blindness is presented. Infiltration with malignant cells was seen in the ciliary bodies at autopsy. Attempts at treatment for this complication are discussed.

Adult↗
PubMed1977

Wide-field resolution in radiography.

Multiple star test objects were placed so as to record the entire field covered on a 35 X 43-cm (14 X 17-in.) film and radiographed to determine the apparent shape of the focal spot and the directions in which degradation is maximum and minimum. It was found that geometric unsharpness decreases along lines radiating outward from the center of the anode shadow. The small focal spots used in magnification may be anticipated to behave in a similar fashion. It was also shown experimentally that truly lateral resolution is approximately constant over the field. A theoretical explanation for this finding is offered.

Radiographic Image Enhancement↗
PubMed1976

Electronic grids for electrostatic imaging systems.

Electronic grids have been substituted for conventional grids in an electrostatic imaging system and have been useful in chest radiography. Electronic grids also appear to be useful for clean-up of small amounts of scattered radiation in radiographs of the extremities. More clinical work is needed before a statement about the use of electronic grids for other examinations can be made.

Electronics, Medical↗
PubMedDate not supplied

Wiener index extension by counting even/odd graph distances.

Chemical structures of organic compounds are characterized numerically by a variety of structural descriptors, one of the earliest and most widely used being the Wiener index W, derived from the interatomic distances in a molecular graph. Extensive use of such structural descriptors or topological indices has been made in drug design, screening of chemical databases, and similarity and diversity assessment. A new set of topological indices is introduced representing a partitioning of the Wiener index based on counts of even and odd molecular graph distances. These new indices are further generalized by weighting exponents which can be optimized during the quantitative structure-activity/-property relationship (QSAR/QSPR) modeling process. These novel topological indices are tested in QSPR models for the boiling temperature, molar heat capacity, standard Gibbs energy of formation, vaporization enthalpy, refractive index, and density of alkanes. In many cases, the even/odd distance indices proposed here give notably improved correlations.

Journal Article↗