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Biomedical subjects

R S Anderson

Publications and source records attributed to R S Anderson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Proteolytic changes in main intrinsic polypeptide (MIP26) from membranes in selenite cataract.

Experimental nuclear cataract produced by an overdose of sodium selenite exhibited limited proteolysis, including breakdown of main intrinsic polypeptide (MIP26) to 24 and 22 kD fragments. Micro-sequencing and site specific immunologic probes were used in the present study to determine regions of cleavage in MIP26 during selenite cataractogenesis. Data suggested that proteolysis occurred in the C-terminus of MIP26. This may have lead to exposure of normally hidden amino acid residues on the C-terminal extension of MIP26. Loss of antigenicity of the N-terminus occurred. These significant changes to the MIP26 molecule might adversely affect communication between lens fiber cells and contribute to selenite cataract.

Amino Acid Sequence↗
PubMed1988

Gene synthesis technology: recent developments and future prospects.

Gene synthesis is a potentially powerful tool in molecular biology that has not yet reached widespread use because of the relatively high cost and labor-intensive nature of the process. This paper reviews some recent technological developments and current research activities of this laboratory which promise to greatly reduce the cost of gene synthesis and to increase the speed and efficiency of the process. We recently developed an improved device for "segmented" synthesis of oligonucleotides, which utilizes porous Teflon wafers containing derivatized controlled pore glass supports to simultaneously synthesize up to 100 different DNA sequences. The stepwise coupling efficiency with the "wafer synthesis device" is as high as that attained with current automated "gene machines" producing 1-4 oligonucleotides at a time, whereas the reagent usage is only 20-50% that of the current DNA synthesizers. At present, we are optimizing the conditions for rapid, efficient assembly of genes on a solid-phase support, wherein ordered, stepwise annealing/washing is performed to segmentally elongate a "starting" oligonucleotide attached to a solid-phase support. We expect that the wafer synthesis device (operated at reduced scale of synthesis), together with solid-phase gene assembly, will permit the synthesis and assembly of an average size gene (1 kb) in one week at a cost of less than $1000. These developments should make gene synthesis a routine and powerful tool in molecular biology.

Biotechnology↗
PubMed1988

Histologic changes in selenite cortical cataract.

Massive cortical cataract was produced 15-30 days after a single injection of an overdose of sodium selenite into 14-day-old rats. Most of the cortical cataract appeared to be due to extensive liquefaction of cortical fibers. Water influx, following initial damage to the epithelium by selenium, and action of lens proteases were probable mechanisms for the extensive liquefaction. Remarkably, selenite cortical cataract spontaneously cleared after several months, restoring essentially normal cells to the epithelium and outer and mid-cortex. Major mechanisms for clearing probably involved: (1) removal of damaged proteins from the lens by extensive proteolysis; and (2) replacement of fibers by resumption of normal fibergenesis. The data emphasized the remarkable reparative potential of the lens, and indicated the usefulness of the selenite cortical cataract as a model to study such processes.

Animals↗
PubMed1987

Genetic relatedness of human DNA polymerase beta and terminal deoxynucleotidyltransferase.

The Protein Identification Resource (PIR) protein sequence data bank was searched for sequence similarity between known proteins and human DNA polymerase beta (Pol beta) or human terminal deoxynucleotidyltransferase (TdT). Pol beta and TdT were found to exhibit amino acid sequence similarity only with each other and not with any other of the 4750 entries in release 12.0 of the PIR data bank. Optimal amino acid sequence alignment of the entire 39-kDa Pol beta polypeptide with the C-terminal two thirds of TdT revealed 24% identical aa residues and 21% conservative aa substitutions. The Monte Carlo score of 12.6 for the entire aligned sequences indicates highly significant aa sequence homology. The hydropathicity profiles of the aligned aa sequences were remarkably similar throughout, suggesting structural similarity of the polypeptides. The most significant regions of homology are aa residues 39-224 and 311-333 of Pol beta vs. aa residues 191-374 and 484-506 of TdT. In addition, weaker homology was seen between a large portion of the 'nonessential' N-terminal end of TdT (aa residues 33-130) and the first region of strong homology between the two proteins (aa residues 31-128 of Pol beta and aa residues 183-280 of TdT), suggestive of genetic duplication within the ancestral gene. On the basis of nucleotide differences between conserved regions of Pol beta and TdT genes (aligned according to optimally aligned aa sequences) it was estimated that Pol beta and TdT diverged on the order of 250 million years ago, corresponding roughly to a time before radiation of mammals and birds.

Amino Acid Sequence↗
PubMed1987

Mechanisms of continence during raised intra-abdominal pressure.

Patients undergoing Stamey endoscopic bladder neck suspension were investigated urodynamically to ascertain the contribution of passive and active components in the maintenance of continence. Transmission of pressure to the proximal urethra was improved by the procedure even under muscular paralysis. This suggests that passive effects due to intra-abdominal replacement of the urethra are most significant.

Abdomen↗
PubMed1987

Selenite cataract: a review.

Selenite cataract is a fairly recently described, experimental animal model for cataract (1). Selenite cataract has been extensively characterized histologically (2) and biochemically (3,4). The model has been particularly useful for studies on the roles of calcium accumulation and lens proteolysis in cataract formation (4). This review describes current knowledge of the biochemical mechanism for selenite cataract and indicates how the model may be used for further understanding of cataractogenesis in general.

Animals↗
PubMed1986

Improving reproductive efficiency in range cattle: An application of the O'Connor Management System.

One group of 125 Hereford cows from a range herd served as a control, while five management techniques were utilized to determine if reproductive performance could be maximized in another similar group from the same ranch. These five techniques were 60-d calving season, cows in moderate body condition at calving time, calf removal for 48 h at the start of breeding season, cows gaining weight near breeding time, and cows bred by bulls predicted to have high fertility (O'Connor Management System). Under the O'Connor Management System, 6% more cows became pregnant, 14% more weaned calves and calves were born 24 d earlier in the calving season. Consequently, calves weighed 14 kg more at weaning and net profit was increased approximately $39 per cow for cows in the O'Connor system.

Journal Article↗
PubMed1986

Selenite-induced epithelial damage and cortical cataract.

The purposes of these experiments were 1) to measure microscopic changes in the epithelium associated with selenite cataract, and 2) to describe the formation and subsequent clearing of selenite cortical cataract. Fourteen-day old suckling rat pups received a single subcutaneous injection of an overdose of sodium selenite at 2.25 mg Se/kg b.w. Development of cortical cataract was observed by biomicroscopy, and changes in epithelium were studied by light microscopy of flat-mounted lens epithelia. Selenite administration caused cortical cataract 15-30 days after injection in addition to previously characterized nuclear cataract. The cortical cataract progressed through equatorial vacuolization, opacity, and finally clearing of the cataract. Mitosis was suppressed and karyorrhexis was observed in the germinative zone of the epithelium 5 hours after selenite injection. Pathological disorganization of the epithelium followed. Changes included vacuolization, loss of meridional rows, and defective fiber formation. Restoration of epithelial morphology was associated with clearing of cortical opacity. Epithelial damage at 5 hours was the earliest change yet recorded for selenite cataract, and these data are consistent with our working hypothesis that the initial site of attack of selenium in both cortical and nuclear cataract is the lens epithelium.

Age Factors↗
PubMed1985

Phosphorylation of proteoglycans. Identification of phosphorylation sites in chondroitin sulfate-rich region of core protein.

Serine residues, which are the sites of phosphorylation in proteoglycans, were demonstrated to be located on chondroitin sulfate-containing peptides. These peptides appeared to be derived primarily from the chondroitin sulfate-rich region of the proteoglycan core protein. The localization of phosphate moieties in the chondroitin sulfate-containing peptides was observed in all experiments. The phosphate moieties were retained on chondroitin sulfate-containing peptides after the protein core was treated with either papain or trypsin. Two phosphopeptide preparations, derived from chondroitin sulfate-containing peptides of proteoglycan subunits, were extensively purified. These 2 phosphopeptide preparations were shown by carbohydrate analysis to be free of keratan sulfate-containing peptides or peptides from the hyaluronic acid binding region of the core protein. One of the phosphopeptide preparations had a phosphate: serine molar ratio of 0.40. This indicated that nearly one-half of the serine residues were phosphorylated rather than glycosylated. Peptides derived from the core protein that contained keratan sulfate had no phosphate moieties.

Cartilage, Articular↗
PubMed1985

Histologic changes during selenite cataractogenesis: a light microscopy study.

The purpose of this research was to study the early histologic changes occurring in the lens during the formation of selenite overdose cataract. Fourteen-day-old rat pups received a single injection of 2.25 mg Se (kg body wt)-1. Lenses at each of three stages of cataract formation were observed biomicroscopically, and then 1-2 micron sections of methacrylate-embedded lenses were evaluated with the light microscope. The first observable change was vacuolization, which started at the lens bow and later spread throughout the posterior subcapsular region (Stage 1). This was followed by an abrupt increase in basophilia at the interface between the peripheral nucleus and cortex (Stage 2). Subsequent formation of nuclear opacity was characterized by the presence of opaque particles, abnormal basophilic structures, and lens fiber damage (Stage 3). The data were consistent with the hypothesis that an early site of attack of selenite is at or near the lens bow, and this leads to biochemical changes, fiber cell damage, impaired nutrient circulation, and formation of nuclear cataract.

Animals↗
PubMed1984

Phosphorylation of proteoglycans from human articular cartilage.

Previous studies have shown that sulfated proteoglycans from human articular and epiphyseal cartilage were phosphorylated. These macromolecules contribute to the stiffness and resiliency of this tissue. We demonstrate here that the phosphate moieties are an integral part of proteoglycan subunits. Specifically, evidence is presented which indicates that proteoglycan monomers contain 3 to 4 phosphate moieties per core protein and that these appear to exist as phosphoserine residues. Furthermore, the data illustrate that human articular cartilage also contains more than 20 different phosphoproteins, some of which are closely associated with proteoglycan aggregates. Proteoglycan subunits were purified from extracts of articular cartilage or from media fractions which had been used to label tissue specimens with 32P-orthophosphate. Chemical and radiographic analyses revealed that the phosphate concentration with respect to sulfate and uronic acid content remained constant when purified proteoglycan monomers were subjected to equilibrium ultracentrifugation and size-exclusion chromatography. That the phosphate moieties were bound to proteoglycan monomers via monoester linkages was indicated by the release of 32P-orthophosphate from proteoglycan subunits incubated under mild alkaline conditions or reacted with acid or alkaline phosphatases. Identification of serine residues in the core protein as the sites of phosphorylation was made by autoradiography of thin layer plates on which hydrolyzed samples of purified 32P-proteoglycan subunits had been subjected to 2-dimensional electrophoresis/chromatography. Quantification of 3 to 4 phosphate moieties per core protein of 200,000 daltons was made by chemical analysis of inorganic phosphate released from proteoglycans by acid hydrolysis.

Adult↗
PubMed1984

Phosphorylation of proteoglycans from human articular cartilage by a cAMP-dependent protein kinase.

Purified proteoglycan subunits from human articular, bovine articular and nasal cartilages, and a rat chondrosarcoma were phosphorylated in vitro by beef heart cAMP-dependent protein kinase in the presence of gamma 32P-ATP. In these experiments, a maximum of 1.7 moles of 32P were incorporated per mole of proteoglycan from human cartilage. Phosphorylation was dependent on the presence of cAMP. Analysis by autoradiography revealed that serine residues in the core protein of the proteoglycan were the sites of phosphorylation. Treatment of proteoglycan subunits with chondroitinase ABC and alkaline phosphatase prior to reaction with cAMP-dependent protein kinase increased the incorporation of 32P by 12-30% when compared with untreated proteoglycans. These data indicate that proteoglycans in cartilage can be phosphorylated by cAMP-dependent protein kinase.

Animals↗
PubMed1984

A neurogenic element to urinary genuine stress incontinence.

The motor unit fibre density in the external anal sphincter has been measured in 35 women with genuine stress incontinence and in 14 continent women. The mean (SD) fibre density in the normal women was 1.5 (0.15) and in the incontinent women it was 1.96 (0.34) (P less than 0.002). These data provide evidence of peripheral denervation of the external anal sphincter and imply synchronous denervation of the pelvic floor muscles. It is suggested that denervation is an aetiological factor in genuine stress incontinence.

Action Potentials↗
PubMed1983

Early development of selenium-induced cataract: slit lamp evaluation.

The purpose of our research was to document early lenticular changes preceding cataract formation in rats receiving an elevated dose of selenium. The following stages were observed after selenium injection: Stage 1 (13-24 hr post-injection), formation of posterior equatorial subcapsular cataract (PESC); Stage 2 (24-72 hr), decline of the PESC, development of a prominent 'washer' shaped change in the refraction of the cortex, and first appearance of swollen fibers around the nucleus; Stage 3 (three to five days), appearance of bilateral dense central nuclear cataracts and further development of perinuclear swollen fibers; Stage 4 (five to 10 days), some nuclear cataracts became more opaque and/or angular. The results are consistent with the hypothesis that the initial site of action of selenium in nuclear cataract formation is not in the lens nucleus. Rather, selenium causes early changes outside the nucleus, which are followed by nuclear cataracts.

Animals↗