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Biomedical subjects

J Berger

Publications and source records attributed to J Berger.

At least 325 records · Page 18Linked to original sources
PubMed1988

COOH-terminal requirements for the correct processing of a phosphatidylinositol-glycan anchored membrane protein.

Placental alkaline phosphatase (PLAP) is anchored to the plasma membrane by a phosphatidylinositol-glycan (PI-G) moiety. During processing of nascent PLAP, a 29-residue COOH-terminal peptide is cleaved out and the PI-G moiety is attached to the newly created COOH terminus of the mature protein. To investigate the structural requirements of the COOH terminus of the nascent protein for PI-G tailing and anchoring to the plasma membrane, we have transfected COS cells with wild type and mutant forms of cDNA encoding human prepro-PLAP. Utilizing a series of COOH-terminal deletion mutants of prepro-PLAP, it was found that to be PI-G-tailed the newly synthesized protein must possess an uncharged, predominantly hydrophobic amino acid sequence of a minimal length in the COOH-terminal peptide. While forms of prepro-PLAP with 17 consecutive hydrophobic residues in the terminal sequence yielded PI-G-tailed and membrane-bound products, prepro-PLAP mutants with 13 or fewer of such residues yielded hydrophilic proteins that were no longer PI-G-tailed but efficiently secreted into the medium. Studies using cassette mutants demonstrated that the precise amino sequence of the COOH-terminal region could be altered as long as minimal hydrophobicity and length was maintained.

Alkaline Phosphatase↗
PubMed1988

Secreted placental alkaline phosphatase: a powerful new quantitative indicator of gene expression in eukaryotic cells.

This paper describes a novel eukaryotic reporter gene, secreted alkaline phosphatase (SEAP). In transient expression experiments using transfected mammalian cells, we demonstrate that SEAP yields results that are qualitatively and quantitatively similar, at both the mRNA and protein levels, to parallel results obtained using established reporter genes. However, SEAP offers significant advantages in terms of ease of assay and assay expense, and also has the potential for quantitative assay at levels as low as 0.2 pg/ml of culture medium. These attributes suggest that SEAP may have general utility in experiments which rely on the accurate measurement of reporter gene expression levels.

Alkaline Phosphatase↗
PubMed1988

Site-directed antibodies for probing the structure and biogenesis of phosphatidylinositol glycan-linked membrane proteins: application to placental alkaline phosphatase.

An immunological approach to the study of the structure and biogenesis of the phosphatidylinositol glycan (PI-G) membrane anchor at the carboxyl terminus of human placental alkaline phosphatase (PLAP) is described. Based on the protein sequence predicted from full length PLAP cDNA, two epitopes were chosen in the region of the carboxyl terminus for the production of site-directed antibodies. The exo site represents the last nine residues of preproPLAP, (res. 505-513), which is part of the sequence that is expected to be cleaved from the nascent protein during processing and addition of the PI-G tail. A second site, the endo sequence, was selected close to the expected carboxyl terminus in mature PI-G-tailed PLAP (res. 474-484 of proPLAP). The two peptides were synthesized, polyclonal antibodies to the conjugated peptides were prepared, and the antisera were characterized. Analytical methods for both synthetic peptides and proteins are presented. Preliminary applications to the isolation and characterization of the PI-G-linked carboxyl terminus of mature PLAP and to the characterization of nascent PLAP are described. The application of both carboxyl terminal-directed antibodies, and a third antibody directed to the amino terminus of mature PLAP, in studies employing mutant forms of PLAP and to the PI-G tailing process itself are discussed. The immunological approach used here for PLAP should be applicable generally to the study of other PI-G-tailed proteins.

Alkaline Phosphatase↗
PubMed1988

Comparison of different antigen preparations in an evaluation of the immune response to Campylobacter pylori.

This study presents a novel approach to the analysis of protein antigens of Campylobacter pylori for use in serology. Protein fractions of this bacterium were resolved in polyacrylamide gel electrophoresis, eluted from gel strips in an electric field and used for coating of microtiter plates in an ELISA-type assay run with a small set of sera from both infected and non-infected patients. Reactivity and discriminative power of the different fractionated antigens (1-9) and crude antigen preparations (A-C) were compared. Better discrimination was achieved between positive and negative sera with high molecular weight fractionated preparations (antigens 8 and 9) than with low molecular weight fractions. Among the crude antigen preparations, antigens A (sonicated whole cells) and C (ultracentrifugated sonicate) seem to have a better discriminative power than antigen B (acid glycin extract).

Antibodies, Bacterial↗
PubMed1988

A double-blind comparative study of doxazosin and nitrendipine in patients with mild-to-moderate essential hypertension.

The antihypertensive efficacy and safety of doxazosin, a selective alpha 1-inhibitor, were compared with nitrendipine. Seventy-two hypertensive patients were entered into the 18-week, double-blind parallel group study, which involved three phases: a 4-week baseline period, a 10-week period in which patients received 1 to 8 mg of doxazosin or 10 and 20 mg of nitrendipine once daily, and a 4-week maintenance period. For all patients, the mean final daily doses were 2.5 mg for doxazosin and 13.9 mg for nitrendipine. In efficacy evaluable patients the percentages of therapy successes (standing diastolic blood pressure less than or equal to 90 mm Hg with greater than or equal to 5 mm Hg reduction or greater than or equal to 10 mm Hg decrease) were comparable for doxazosin (94%) and nitrendipine (91%), as was the proportion in whom blood pressure was "normalized" (standing diastolic blood pressure less than or equal to 90 mm Hg), 91% and 85, respectively. Blood pressures (diastolic and systolic in supine and standing positions) were significantly reduced (p less than 0.05) at all visits in both treatment groups. Ten patients (28%) in each treatment group experienced at least one adverse event. No clinically significant laboratory changes were apparent in either the doxazosin or nitrendipine groups, and no trends were observed with regard to organ systems or correlations with dose or duration of treatments. The investigators' global assessment of efficacy was rated excellent or good for all doxazosin-treated patients and excellent or good for 32 and fair for four in the nitrendipine group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1988

Distribution of O6-ethylguanine in DNA exposed to ethylnitrosourea in vitro as visualized by electron microscopy using a monoclonal antibody.

Application of a monoclonal antibody (Mab ER-6; Rajewsky et al., 1980) specific for O6-ethyl-2'-deoxyguanosine (O6-EtdGuo), in conjunction with a protein-free spreading procedure for double-stranded DNA molecules and transmission electron microscopy, permits the visualization of antibody molecules complexed to O6-EtdGuo residues formed in DNA upon reaction with the carcinogen N-ethyl-N-nitrosourea (EtNU) (Nehls et al., 1984). To obtain information on the distribution of O6-EtdGuo in native DNA exposed to EtNU in vitro, samples of purified rat brain DNA were briefly incubated with EtNU at concentrations differing by a factor of 8 (0.5 and 4 mg of EtNU/ml, respectively). As determined in DNA hydrolysates by competitive radioimmunoassay, the resulting DNA preparations contained O6-EtdGuo at O6-EtdGuo/2'-deoxyguanosine molar ratios of 15.1 X 10(-5) and 116 X 10(-5), respectively. Interspace distances between Mab-binding sites in both sets of ethylated DNA were determined by electron microscopy both in individual DNA fragments of different size, and in computer-generated, long-thread DNA constructs. Comparative statistical analyses by a newly developed MOLRANDO computer program show a non-random distribution pattern of Mab-binding O6-EtdGuo residues.

Animals↗
PubMed1988

Worldwide perspective of IgA nephropathy.

It is becoming evident that IgA nephropathy (IgAN) is the most common glomerular disease, and a frequent cause of end-stage renal failure in both white and Asian populations. Its significance as a public health problem is not known since little epidemiologic research is available in most countries. The apparent geographic variations in the percentage of IgAN in kidney biopsy specimens may reflect different clinical policies for diagnostic tests. As a consequence, the frequency of IgAN cannot be accurately extrapolated from these data for any given population. The highest percentages, reported in Singapore and Japan, may be influenced by the systematic screening of urines in both countries. By contrast, IgAN has been detected rarely in blacks either from the United States or from Africa. However, biopsies are performed infrequently in African patients with only microscopic hematuria. Such ethnic differences may suggest a possible role of genetic factors in the etiology of IgAN. As shown recently in France and Italy, antibiotic therapy of streptococcal infections apparently has not influenced the percentage of IgAN in kidney biopsy specimens. These facts and the rarity of the glomerulonephritis in blacks suggest that infections may not be responsible for the etiology of IgAN. The traditional search for causal agents should be approached more vigorously. It will require innovative epidemiologic efforts to understand the mechanisms by which multiple factors (environmental and genetic) acting together influence the risk of disease.

Biopsy↗
PubMed1988

Recurrence of IgA nephropathy in renal allografts.

Mesangial IgA deposits recur in about half of the patients receiving a renal allograft for end-stage renal disease due to IgA nephropathy. However, the course of the recurrent disease is usually mild and rarely causes decreased function of the allograft.

Biopsy↗
PubMed1988

Intestinal zinc and carboxypeptidase A and B activity in response to consumption of test meals containing various proteins by rats.

Rats were fed test meals containing 23% protein as casein (C), soy protein isolate (SPI) or egg white (EW) to assess effects of dietary protein sources on te amount of zinc and carboxypeptidase (CP, CPA, CPB) activity in the small intestinal contents. Groups of six rats each were killed at 1, 2.5 and 5 h postprandial and six rats fasted for 19 h served as a 0 time control. Consumption of a test meal increased the weight of small intestinal contents at 1 and 2.5 h compared with unfed animals and in a similar manner for all three protein sources. However, at various times during the postprandial period differences in the level of zinc and CP activity within the small intestinal contents among the three dietary protein sources were observed. Both the SPI and EW groups had significantly higher levels of CPA and CPB activity at 1 h postprandial than the C group. Only in the SPI group was the intestinal level of zinc increased at 1 and 2.5 h compared with the unfed group. At 1 and 2.5 h postprandial intestinal zinc was significantly higher in the SPI group than in the C and EW groups. The results indicate that the disappearance of zinc from the intestine is delayed in rats fed SPI, probably because of the presence of phytate.

Animals↗
PubMed1988

Neoadjuvant chemotherapy of osteosarcoma: results of a randomized cooperative trial (COSS-82) with salvage chemotherapy based on histological tumor response.

Following observation of the predictive value of the histologic extent of tumor cell destruction after preoperative chemotherapy for metastasis-free survival (MFS) in osteosarcoma, a randomized study was undertaken with the aim of (1) sparing some patients the unpleasant side effects of highly toxic drugs like doxorubicin (DOX) and cisplatin (CPDD) by administering these drugs postoperatively only after poor response with a milder preoperative regimen, and (2) improving the prognosis of patients responding poorly to the initial treatment by use of a salvage chemotherapy postoperatively. The available patients were divided into two groups. Those in the study arm received a preoperative chemotherapy consisting of high-dose methotrexate (HDMTX) and the triple drug combination of bleomycin, cyclophosphamide, and dactinomycin (BCD) and were switched to DOX/CPDD postoperatively in case of poor response. DOX/CPDD was used besides HDMTX for initial treatment in the control arm, and BCD alternatively with CPDD/ifosfamide (IFO) for postoperative salvage treatment. The response rate of the study arm was significantly inferior to the control arm (26% v 60%; P less than .001). The actuarial 4-year MFS rate of poor responders after salvage chemotherapy also was poorest in the study arm (41%); it was unchanged in the control arm (53%) as compared with that of poor responders from the COSS-80 study without salvage chemotherapy (52%). The actuarial 4-year MFS rate of good responders was 73% in the study arm, 79% in the control arm, and not significantly different from that of the COSS-80 study (84%), although postoperative chemotherapy of good responders had been markedly shortened as compared with the COSS-80 study. The actuarial 4-year MFS rate of the study arm as a whole was inferior to that of the control arm (49% v 68%; P less than .1) and also inferior to the COSS-80 study (68%; P less than .01), indicating a failure of the employed salvage strategy in general and especially of the effort to restrict the use of the very effective but highly toxic drugs DOX and CPDD to patients resistant to a less toxic initial treatment.

Actuarial Analysis↗
PubMed1988

Reduced and total ascorbate in guinea pig eye tissues in response to dietary intake.

Guinea pigs were fed 5 different levels of dietary ascorbate representing a 65-fold range (0.8-52 mg animal-1 day-1). After two months on the diets, levels of reduced and total ascorbate were determined in aqueous humor, vitreous humor, lens and plasma. At low-dietary levels, proportionally higher levels of ascorbate are found in the lens than in other eye tissues. Tissue ascorbate levels began to plateau at dietary intake of approximately 11 mg animal-1 day-1. This is the amount suggested for optimal health, but it is ten times the level needed to prevent scurvy. Over 75% of the eye tissue ascorbate is in the reduced form in animals fed diets which provided 11 mg ascorbate. However, there was less than 50% reduced ascorbate in the eye tissues of the animals fed about 1mg ascorbate per day.

Animals↗
PubMed1988

Overwinter survival of carfentanil-immobilized male bison.

A problem with studies that examine immobilization-related drug effects on large mammals is that no true control group exists because untreated (non-captured) animals in the same population have not been examined. We present data to show that overwinter survival in male bison (Bison bison) immobilized with carfentanil was the same as untreated bison. This unique experimental design allows us to conclude that the drug had no long-term effect on male bison overwinter survival.

Animals↗
PubMed1988

Cyclophosphamide induced generation of giant hypersegmented granulocytes in rat bone marrow: cell cycle distribution and silver nucleolar staining.

Daily injection of cyclophosphamide (20 mg/kg body weight) for 7 days resulted in accumulation of 50% of rat bone marrow granulocytes in G2. Tetraploid neutrophils were hypersegmented (7.25 +/- 0.33) in comparison with diploid ones (3.92 +/- 0.33). After 14 days of cyclophosphamide treatment tetraploid hypersegmented neutrophils could be found in peripheral blood. Diploid neutrophils in these animals were also hypersegmented (4.78 +/- 0.14 versus 3.15 +/- 0.02 in control, p less than 0.001). Nucleolar ribosomal gene activities, evaluated by morphometry of silver nucleolar grains, decreased on bone marrow granulocytes in the course of differentiation in control rats. After cyclophosphamide treatment mature granulocytes contained more silver grains than in controls which may be explained by conservation of silver binding sites of nucleoli from the stages of promyelocytes and myelocytes. These results suggest two mechanisms of hypersegmented neutrophil, generation in cyclophosphamide treated rats: the first, via maturation of myelocytes arrested in G2, and second, a direct one, without tetraploid granulocyte involvement.

Animals↗