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Biomedical subjects

D Roll

Publications and source records attributed to D Roll.

At least 19 recordsLinked to original sources
PubMed1998

Imprinted H19 oncofetal RNA is a candidate tumour marker for hepatocellular carcinoma.

AIMS/BACKGROUND: To study the expression of the H19 gene in hepatocellular carcinoma. H19 is an imprinted, maternally expressed gene, which is tightly linked, both physically and functionally, to the paternally expressed insulin-like growth factor 2 (IGF II). IGF II is known to be involved in liver carcinogenesis. H19 was first discovered in the fetal mouse liver to be under the same regulatory genes as alpha fetoprotein (alpha FP), a widely used tumour marker for hepatocellular carcinoma. METHODS: Using both radioactive and non-radioactive in situ hybridisation, the expression of the H19 gene was compared with the presence of alpha FP, as demonstrated by immunohistochemistry, in 18 cases of hepatocellular carcinoma. RESULTS: H19 expression was present in 13 of 18 cases, whereas staining for alpha FP was positive in only nine of 18 cases. Concordance was found in 12 of 18 tumours (66.7%). In general, the staining pattern for H19 was more diffuse than the immunohistochemical staining for alpha FP. CONCLUSIONS: The addition of a non-radioactive in situ hybridisation assay for H19 RNA to the panel of tumour markers used for the histopathological and cytological diagnosis of hepatocellular carcinoma might be useful.

Adult↗
PubMed1997

Polycystic ovary syndrome. An autoimmune disease?

OBJECTIVE: To determine whether there is an autoimmune cause of polycystic ovary disease (PCOD) implicating antiovarian antibodies in the pathophysiology of the syndrome. STUDY DESIGN: This study examined 31 women diagnosed as having PCOD according to internationally recognized criteria and who attended our infertility clinic during 1994-1995. RESULTS: We could not confirm the findings of previous studies. Only one patient in our group with type II diabetes mellitus had antiovarian antibodies present in her serum. CONCLUSION: It seems that an autoimmune mechanism probably is not of prime importance in this multifaceted syndrome.

Adult↗
PubMed1996

Single-case experimental designs in medical education: an innovative research method.

This paper presents an argument for more extensive use of single-case experimental research designs in medical education research. Single-case experimental designs consist of a group of experimental techniques that are widely used in the social sciences but are just beginning to be utilized by medical researchers. The method emphasizes reliable observations of behavior, repeated measurements of outcome, and individualized tailoring of objectives for each subject; all of these occur within a system that allows an experimental analysis to be conducted. Single-case designs are particularly useful when only small numbers of participants are available for a relatively long period of time. Trends in medical education toward individualized instruction, adult-centered learning, and fine-grained analyses of medical skills and knowledge make this field especially amenable to single-case experimental designs. Issues of internal and external validity, generality, practicality, and ethics are discussed, and several typical designs are illustrated. While the emergence of qualitative research methods in medical education may prove useful, single-case designs can maintain experimental science's emphasis on methodologic rigor, while allowing the flexibility often needed to conduct research in applied settings.

Education, Medical↗
PubMed1993

Expression and translocation of the chlamydial major outer membrane protein in Escherichia coli.

The entire gene encoding the major outer membrane protein (MOMP) from Chlamydia psittaci strain GPIC has been cloned and expressed in Escherichia coli. A tightly regulated T7 promoter is used to control expression of the protein in Escherichia coli. Upon induction of expression, the precursor (pre-MOMP) is synthesized in the cell. This is followed by the appearance of a lower molecular weight protein that comigrates with mature MOMP from chlamydial elementary bodies by both one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis. When E. coli cells expressing MOMP are converted to spheroplasts and subjected to protease treatment, MOMP is quantitatively degraded while cytoplasmic pre-MOMP is protected from degradation. Whole cells subjected to the same protease treatment show no degradation of MOMP. Furthermore, MOMP is not detected in surface-labeling experiments using several MOMP-specific antibodies. These data indicate that pre-MOMP is translocated to the periplasmic space and processed but is not surface exposed in E. coli. Expression of MOMP in this system causes a significant reduction in cell viability. In addition, coexpression in E. coli of MOMP or a MOMP-PhoA fusion with various chaperone proteins does not alter the level of MOMP translocation.

Amino Acid Sequence↗
PubMed1992

Blood rheology in acute myocardial infarction: effects of high-dose i.v. streptokinase compared to placebo.

To compare the haemorheological effects of an i.v. infusion of 1.5 MU of streptokinase with placebo, we investigated the time course of plasma fibrinogen concentration and the haemorheologic parameters plasma viscosity, erythrocyte aggregation and whole blood viscosity at different shear rates during the early phase of acute myocardial infarction until week 3 in 38 unselected patients from the ISAM and ISIS-2 study. Within 3 h, streptokinase led to a near afibrinogenaemia lasting for more than 24 h. Concomitantly, with streptokinase we found a reduction of plasma viscosity, erythrocyte aggregation and whole blood viscosity, whereas with placebo, values showed a slight increase, resulting in significant differences between the groups within the first 2 days. Thereafter, both groups showed an increase in all parameters, values reaching a maximum after 1 week. The streptokinase-induced reduction in blood viscosity may lead to an improvement in microcirculation in the infarction area during the early phase, whereas the hyperviscosity observed independently of therapy after 1 week may lead to an impairment of microcirculation.

Adult↗
PubMed1990

[A comparison of different methods of calculating clearances using 99mTc-mercaptoacetyltriglycine and 123I- or 131I-ortho-iodohippuric acid].

Using labelled MAG3 (n = 172) or OIH (n = 102) the results of three different techniques of calculating renal clearance were compared. The following techniques were used: Tauxe (single plasma concentration determination), Oberhausen (modified, combined partial body and plasma disappearance clearance) and Winkler (partial body clearance). For OIH, linear regression analysis revealed a positive correlation of Tauxe and Oberhausen clearances with a correlation coefficient (r) of 0.90 and a mean ratio (mean) Oberhausen/Tauxe clearances of 1.03. For MAG3, the Oberhausen values were found to be significantly lower than the Tauxe values with an equally good correlation. For this radiopharmaceutical the Winkler values were significantly higher than the Tauxe and Oberhausen values. For OIH, no such difference was noted. However, the correlation coefficient was significantly lower. Whereas with the Tauxe method, a mean ratio MAG3-/OIH clearances of 0.62 was observed in an earlier investigation, from the present data a ratio of 0.53 is calculated for the Oberhausen clearance. The difference between the Tauxe and Oberhausen clearances with MAG3 is of importance when comparing clearance values obtained with clearance calculation techniques and for establishing normal values for the MAG3 clearance.

Adult↗
PubMed1989

Identification of consensus epitope structures expressed in recombinant DNA libraries.

In the course of screening cDNA expression libraries with a monospecific polyclonal antibody to topoisomerase I, we isolated three different immunopositive cDNA clones. By comparing their derived amino acid sequences, a consensus region of similarity in otherwise completely dissimilar sequences was identified as an epitope. The approach described here should identify both continuous and discontinuous topological epitopes. The probability of occurrence of "spurious" immunopositive clones is shown to depend on the number of codons of each critical amino acid within the antigenic determinant.

Amino Acid Sequence↗
PubMed1988

Grand multiparity: an obstetric or neonatal risk factor?

Grand multiparity has been considered to be a factor in maternal and neonatal morbidity. In addition, families with seven or more children have been associated with low socioeconomic status. To minimize the confounding effect of the socioeconomic status, the outcome of grand multiparity has been investigated in a mostly homogeneous, ultraorthodox Jewish community in Jerusalem, Israel. A total of 5916 deliveries in one community hospital (Bikur Cholim) were studied, of which 893 (13%) occurred in mothers who had given birth to seven or more infants. There was a significant decrease in the incidence of small for gestational age infants among the grand multiparous women (3.6% as opposed to 5.8% in the control population). This difference was independent of maternal age. Moreover, grand multiparous women gave birth to significantly more large for gestational age infants. No increase in obstetric complications or neonatal morbidity and mortality was found among the offspring of the grand multiparous mothers. Having taken socioeconomic status into account, we conclude that grand multiparity does not carry an increased risk of perinatal morbidity or mortality.

Delivery, Obstetric↗
PubMed1984

Purification and partial characterization of a 19kD/pI 4.5 nucleolar phosphoprotein.

Two-dimensional PAGE analysis of proteins associated with the slowly sedimenting "fibrillar" structures of HeLa nucleoli revealed a protein with a M of 19,000 and a pI of 4.5 which was highly labeled both with 32P-orthophosphate and 35S-methionine. The protein was isolated from Novikoff hepatoma nucleoli by extraction in 0.35 M NaCl and 5 mM DTT followed by chromatography in EDTA on DEAE-cellulose and Sephadex G-100. The protein was homogeneous with respect to two-dimensional PAGE, number of tryptic peptides and carboxyl terminal analysis. The protein contained an acidic/basic amino acid ratio of 2.1, 7 residues of methionine, 2 residues of cysteine, a blocked amino terminus and a carboxyl terminal lysylleucine.

Amino Acids↗
PubMed1983

Phosphorylation of purified Novikoff hepatoma topoisomerase I.

The purified Novikoff hepatoma nuclear phosphoprotein with a molecular weight of 110 kdalton and pI 8.4, was found to be a type I topoisomerase. When isolated from 32P-labeled Novikoff ascites cells or incubated in vitro with protein kinase, phosphoserine was found to be its major phosphorylated amino acid. The enzymatic activity of topoisomerase I was altered by changes in phosphorylation. Its activity was increased by protein kinase and it was decreased by alkaline phosphatase.

Alkaline Phosphatase↗