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Biomedical subjects

R A Berg

Publications and source records attributed to R A Berg.

At least 127 records · Page 7Linked to original sources
PubMed1985

Biosynthesis of prolyl hydroxylase: evidence for two separate dolichol-media pathways of glycosylation.

Prolyl hydroxylase is a glycoprotein containing two nonidentical subunits, alpha and beta. The alpha subunit of prolyl hydroxylase isolated from 13-day-old chick embryos contains a single high mannose oligosaccharide having seven mannosyl residues. Two forms of alpha subunit have been shown to exist in enzyme purified from tendon cells of 17-day-old chick embryos, one of which (alpha) appears to be identical in molecular weight and carbohydrate content with the single alpha of enzyme from 13-day-old chick embryos, as well as another form (alpha') that contains two oligosaccharides, each containing eight mannosyl units [see Kedersha, N. L., Tkacz, J. S., & Berg, R. A. (1985) Biochemistry (preceding paper in this issue)]. Biosynthetic labeling studies were performed with chick tendon cells using [2-3H]mannose, [6-3H]glucosamine, [14C(U)]mannose, and [14C(U)]glucose. Analysis of the labeled products using polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that only the oligosaccharides on alpha' incorporated measurable mannose or glucosamine isotopes; however, both alpha subunits incorporated 14C amino acid mix and [14C(U)]glucose [metabolically converted to [14C(U)]mannose] under similar conditions. Pulse-chase labeling studies using 14C amino acid mix demonstrated that both glycosylated polypeptide chains alpha and alpha' were synthesized simultaneously and that no precursor product relationship between alpha and alpha' was apparent. In the presence of tunicamycin, neither alpha nor alpha' was detected; a single polypeptide of greater mobility appeared instead. Incubation of the cells with inhibitory concentrations of glucosamine partially depressed the glycosylation of alpha' but allowed the glycosylation of alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1985

Nutritional emphysema in the rat. Influence of protein depletion and impaired lung growth.

Emphysema is produced by severe food restriction in rats and is postulated to result from depletion of lung connective tissue. We studied (1) whether total dietary protein depletion worsens nutritional emphysema, and (2) whether the reduced content of lung connective tissue in nutritional emphysema results from lack of accumulation caused by impaired lung growth or by a net loss from the lung. Lewis rats weighing 200 g were restricted to one third food intake with or without protein for 6 wk. Lungs were assessed by morphometry, pressure-volume (P-V) measurements, and content of collagen and elastin. Emphysema was found by morphometry (but not by P-V measurements) in food-restricted rats, and contrary to expectation, emphysema was less severe in those depleted of protein. Collagen and elastin content were reduced in emphysematous lungs; however, the levels were not below those found prior to nutritional intervention, suggesting that lack of growth, not depletion, accounts for the reduced content.

Animals↗
PubMed1985

Academic achievement and intelligence test performance in children with cancer at diagnosis and one year later.

Recent investigations have found significant test-retest decline in certain academic achievement and intelligence test scores in children diagnosed as having acute lymphocytic leukemia (ALL) before 8 years of age. No such effect was observed in children diagnosed at or later than age 8 years. The current study, using a sample of 77 children with ALL, failed to support these findings. No significant differences were found between groups at test or retest nor were significant declines seen for either group from test to retest 1 year later. Reasons for differences in findings between studies, including methodological and samples size differences, are discussed along with implications for future research in this area.

Achievement↗
PubMed1985

Collagen deposition during wound repair.

Collagen fiber diameters, amount of birefringent collagen (brightness) and birefringence retardation were measured in implanted collagen-based sponges containing hyaluronic acid (HA) and fibronectin (FN). In the presence of HA and FN, increased number of fibroblasts and brightness were observed 6 days after wounding. Increased brightness in the presence of HA and FN reflected increased deposition of oriented collagen fibers. From days 9 to 12, increased fiber diameters were similar in implanted collagen-based sponges with or without HA and FN. Increased birefringence retardation in sponges containing HA and FN was consistent with increased packing density of collagen fibers observed by scanning electron microscopy. Our results suggest that HA and FN are effective in promoting fibroblast movement into a collagen sponge and deposition of collagen fibers during the early phases of wound healing. Use of a collagen-based sponge containing HA and FN may enhance collagen deposition in situations where healing is compromised as in the case of dermal ulcers.

Animals↗
PubMed1984

Degradation of soluble collagen by ozone or hydroxyl radicals.

Collagen exposed to ozone or hydroxyl radicals was degraded in a time- and dose-dependent manner. This degradation was inhibited by free radical scavengers. Furthermore, lower levels of these oxidants did not degrade the molecule, but caused it to become susceptible to proteolytic degradation. We suggest an alternative mechanism by which oxygen-derived free radicals participate in the destruction of extracellular matrix observed during acute lung injury by oxidant gas, in addition to the commonly accepted proteinase-antiproteinase theory of lung injury.

Animals↗
PubMed1984

Lysosomal function in the degradation of defective collagen in cultured lung fibroblasts.

Human fibroblasts when induced to make nonhelical , defective collagen have mechanisms for degrading up to 30% of their newly synthesized collagen intracellularly prior to secretion. To determine if at least a portion of the degradation of defective collagen occurs by lysosomes, extracts of cultured HFL-1 fibroblasts were examined for proteinases capable of degrading denatured type I [3H]procollagen. The majority of the proteolytic activity against denatured [3H]-procollagen had a pH optimum of 3.5-4; it was stimulated by dithiothreitol and inhibited 95% by leupeptin, 10% by pepstatin, and 98% by leupeptin and pepstatin together. Extracts of purified lysosomes from the fibroblasts were active in degrading denatured [3H]procollagen and were completely inhibited by leupeptin and pepstatin. To demonstrate directly that human lung fibroblasts can translocate a portion of their defective collagen to lysosomes, cultured cells were incubated with cis-4-hydroxyproline and labeled with [14C]proline to cause the cells to make nonhelical [14C]procollagen. About 3% of the total intracellular hydroxy[14C]proline was found in lysosomes. If, however, the cells were also treated with NH4Cl, an inhibitor of lysosomal function, 18% of the intracellular hydroxy[14C]proline was found in lysosomes. These results demonstrate that cultured human lung fibroblasts induced to make defective collagen are capable of shunting a portion of such collagen to their lysosomes for intracellular degradation.

Cells, Cultured↗
PubMed1984

Emergency infusion of catecholamines into bone marrow.

An emergency infusion of catecholamines into the bone marrow of a 6-month-old infant was performed. We believe this is the first report of continuous intraosseous infusion of dopamine hydrochloride and dobutamine hydrochloride. Intraosseous infusions are efficacious and complications are rare. We recommend use of this technique in emergency circumstances when venous access cannot be obtained.

Bone Marrow↗
PubMed1984

The proteinase inhibitors leupeptin, pepstatin A, and TLCK cause reduced collagen production in freshly isolated embryonic chick fibroblasts in suspension culture.

The production of [14C]proline-labeled collagen by embryonic chick tendon cells in suspension culture is reduced when the cells are incubated in the presence of lysosomotropic agents NH4Cl or chloroquine. Since these agents have multiple effects on fibroblasts, including inhibition of collagen secretion, specific proteinase inhibitors were tested for their effect on collagen production. Here the proteinase inhibitors N-p-tosyl-L-lysine chloromethylketone (TLCK) and leupeptin, specific for certain cysteine and serine proteinases, and pepstatin A, specific for aspartic proteinases, were tested for their effects on both the production and secretion of collagen. When treated with the proteinase inhibitor TLCK, the percentage of protein synthesis devoted to collagen decreased from control levels of 19.0 +/- 1.4% to 10.5 +/- 2.4% with 10 microM TLCK. Collagen synthesis was further reduced to only 1.2% of total protein synthesis with 100 microM TLCK. The incorporation of [14C]proline into collagenase-digestible peptides was only slightly decreased in the samples treated separately with 50 micrograms/ml leupeptin or 60 micrograms/ml pepstatin A. However, the production of collagen was reduced to 10.9 +/- 1.4% of total protein synthesis in samples treated with leupeptin and pepstatin A together. The basal intracellular degradation of newly synthesized, [14C]proline-labeled collagen was not significantly altered by any of the reagents tested, and secretion of the collagen which was produced was not impaired except in samples treated with 100 microM TLCK. The data presented are consistent with the hypothesis that a proteolytic mechanism utilizing some combination of cysteine, serine, and aspartic proteinases is necessary for continued collagen synthesis in freshly isolated embryonic chick tendon fibroblasts, and suggests that a heretofore unknown regulatory system may be operative in controlling the synthesis of collagen in fibroblasts.

Amino Acid Chloromethyl Ketones↗
PubMed1984

Statistical test of a short form of the speech-sounds perception test in a child population.

The adequacy of a shortened version of the children's Speech-Sounds Perception Test was examined. In two different groups of chronically ill children, stepwise multiple regression analysis demonstrated that the first three subtests (first 30 items) accounted for over 87% of the variance in the total 60-item test. The 30-item version appears to be as useful with children as the full 60-item test.

Adolescent↗
PubMed1984

Fibroblast-collagen sponge interactions and the spatial deposition of newly synthesized collagen fibers in vitro and in vivo.

Fibroblast-collagen sponge interactions were studied in cell culture and dermal wound systems. In both models fibroblasts appear to adhere, attach and orient in the presence of type I collagen fibrils. In the presence of fibronectin, purified from bovine blood, adhesion and alignment of fibroblasts appeared to be enhanced as well as the deposition of thick collagen fibers. When collagen sponges were grafted onto full thickness dermal wounds the granulation tissue that was laid down within the collagen sponge appeared to differ from granulation tissue laid down below the collagen sponge or on similar wounds in the absence of a sponge. In the absence of a collagen sponge the granulation tissue is characterized by wavy collagen fibers that exhibit an extinction pattern characteristic of crimped fibers found in tendon when examined under polarized light. In contrast, collagen fibers laid down within the sponge appear to be highly oriented and lack evidence of crimp. These results suggest that the presence of a collagen matrix acts as a template that allows for the organized spatial deposition of newly synthesized collagen fibers. The enhanced biosynthesis of thick collagen fibers in the presence of a collagen sponge containing fibronectin may decrease the remodeling phase that is associated with dermal scarring.

Animals↗
PubMed1983

Ascorbate deficiency results in decreased collagen production: under-hydroxylation of proline leads to increased intracellular degradation.

Collagen production by cultured human lung fibroblasts was examined when the cells were made deficient in ascorbate. Cells grown in the absence of ascorbate produced 30% less collagen during a 6-h labeling period than cells incubated with as little as 1 microgram/ml ascorbate during the labeling period. Cells grown without ascorbate produced under-hydroxylated collagen which was subject to increased intracellular degradation from a basal level of 16% to an enhanced level of 49% of all newly synthesized collagen. The likely mechanism for increased intracellular degradation is the inability of under-hydroxylated collagen to assume a triple-helical conformation causing it to be susceptible to intracellular degradation. Measurement of collagen production by enzyme linked immunoassay (ELISA) using antibodies directed against triple-helical determinants of collagen showed that both types I and III collagens were affected. In contrast, another connective tissue component, fibronectin, was not affected. Analysis by ELISA showed a greater decrease in collagen production than did analysis by the collagenase method, suggesting that some non-helical collagen chains (detected by collagenase but not by ELISA) were secreted in the absence of ascorbate. These results provide a mechanism to account, in part, for the deficiency of collagen in connective tissues which occurs in a state of ascorbate deficiency.

Ascorbic Acid↗
PubMed1983

Familial porencephaly.

We studied familial porencephaly consistent with autosomal dominant or recessive inheritance in two families. The pathogenesis of the encephaloclastic and schizencephalic types was reviewed. Use of noninvasive neuroradiologic techniques, including computed tomography and ultrasonography, may help to delineate groups of children with smaller porencephalic cysts and to define further familial or genetic forms of this process.

Brain Diseases↗
PubMed1983

Evaluation of a successful biosocial rotation.

Efficacy of an eight-week rotation in developmental and behavioral pediatrics for second-year pediatric residents was evaluated. Pretesting and posttesting disclosed that our residents felt more competent with biosocial problems, had more favorable attitudes toward patients with biosocial problems, and had increased factual knowledge in developmental and behavioral pediatrics. When reevaluated 12 to 24 months after rotation as third-year residents (PL-3), they performed better on a factual knowledge test than a PL-3 control group that had not had the rotation. They also felt more competent than the controls in the diagnosis and treatment of children with learning disabilities, hyperactivity, physical handicaps, depression, and gynecologic problems.

Arizona↗
PubMed1983

Regional cerebral blood flow in schizophrenics. Tests using the xenon Xe 133 inhalation method.

Measurements of intrahemispheric and bilateral regional cerebral blood flow (CBF) for gray and white matter were compared in 29 schizophrenic patients and 22 normal controls, using the xenon Xe 133 inhalation method. Results showed significantly lower CBF values for all brain regions in the schizophrenic group, and post hoc comparisons showed relatively greater reduced gray-matter CBF values in the anterior areas of the brain. There was also a left-hemisphere frontal loss similar to that reported previously, although it was in the context of a generalized loss in anterior functioning. Interhemispheric comparison within both groups showed no differences between homologous regions for gray matter, and greater white-matter CBF values in the right hemisphere than in the left hemisphere. The findings support a hypothesis of a bilateral anterior deficit in schizophrenia.

Adolescent↗
PubMed1983

Neuropsychological sequelae of postradiation somnolence syndrome.

Postirradiation somnolence syndrome in children with acute lymphocytic leukemia treated with cranial irradiation has been identified as a possible precursor of later cognitive dysfunction. To test this, the neuropsychological evaluation of 48 children who developed somnolence syndrome was compared with that of 31 children who did not have the syndrome at approximately 1 1/2 and 3 3/4 years after treatment. No differences in performance between the two groups were found on many measures of neuropsychological functioning with the exception of fine motor speed. Children without somnolence syndrome scored somewhat less than normal on measures of academic achievement. No other differences from normal performance were noted in either group. The results of the study indicated that if children with somnolence are at greater risk for the development of cognitive dysfunction than those not manifesting the syndrome, such risks occur at a time farther from treatment than 3 to 4 years.

Adolescent↗