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Biomedical subjects

J Russell

Publications and source records attributed to J Russell.

At least 307 records · Page 17Linked to original sources
PubMed1982

Perinatal mortality: the current debate.

Using the parliamentary 'Short Report' on perinatal and neonatal mortality as a focus for analysis, this paper attempts a critical examination of recent trends in perinatal health policy debate, and suggests a polemical explanation of such trends. The paper begins by outlining the major concerns of current debate and unravelling the assumptions and apparent contradictions in both 'official' and popular arguments. It then utilises a framework and perspective adopted by Lewis in her recently published analysis of Edwardian maternal and infant welfare policy, in an attempt to make sense of the major contradictions identified. The importance of considering the ideological 'ends' of social policy movements--in this instance, a restating of the ideology of motherhood--over and above purported societal 'needs'--i.e. a reduction in perinatal mortality rates--is highlighted.

Epidemiologic Methods↗
PubMed1982

Canine intestinal ulcer: myoelectric components and the effect of chronic hypergastrinemia.

The effects of jejunal ulcer and chronic endogenous hypergastrinemia on canine gastrointestinal myoelectric activity were investigated in three groups of dogs. All dogs were chronically implanted with electrodes on the stomach and either the duodenum or jejunum. Fasted-state myoelectric activity was monitored before and after gastroenterostomy. Two groups of dogs underwent autotransplantation of the gastric antrum to the midcolon with either gastroduodenostomy or gastrojejunostomy. The third group of dogs underwent diversion of the antroduodenum with gastrojejunostomy. Chronic hypergastrinemia was observed postoperatively in the dogs of each of the three models. Only dogs with gastrojejunostomy and antrocolic transplant developed intestinal ulcers. None of the dogs, despite the presence of ulcers in one group, demonstrated significant changes in myoelectric activity. In both gastrojejunostomy models, a trend toward lengthened interdigesive phase 2 at the expense of phase 1 was seen. No other myoelectric changes were observed and chronic hypergastrinemia had no effect on myoelectric activity in these models. We conclude; (a) experimental jejunal peptic ulcer is not marked by significant changes in interdigestive myoelectric activity and (b) chronic hypergastrinemia is not accompanied by the gastrointestinal muscle, effects reported after acute treatment with gastrin, suggesting a tolerance.

Animals↗
PubMed1982

The Cincinnati Lipid Research Clinic family study: cultural and biological determinants of lipids and lipoprotein concentrations.

A general linear model is described here for cultural and biological inheritance of lipids and lipoproteins. This model involves 10 parameters to be estimated from a total of 17 correlations, leaving ample degrees of freedom to test the goodness of fit. The model fits very well to each of the five lipid and lipoprotein variables analyzed here from a Lipid Research Clinic family data set. Both genetic and cultural inheritance are significant for each trait with the single exception that triglyceride levels fail to support genetic inheritance. Under the most parsimonious hypothesis, the genetic heritability (h2) ranges from .194 +/- .092 for triglyceride to .624 +/- .093 for low-density lipoprotein-cholesterol. Cultural heritability ranges from .070 +/- .030 for total cholesterol to .149 +/- .034 for triglyceride.

Adult↗
PubMed1981

The single tryptophan residue of human placental lactogen. Effects of modification and cleavage on biologic activity and protein conformation.

In order to define further the chemical features of the human placental lactogen (hPL) molecule responsible for its lactogenic activity, two derivatives of the hormone were prepared by treatment with BNPS-skatole (2-nitrophenylsulfenyl)-3-methyl-3'-bromoindolenine). At a molar ratio of reagent to hPL of 7:1, a derivative was produced in which the single tryptophan was completely oxidized. At higher ratios, a second derivative was formed in which the peptide chain was cleaved at the tryptophan residue and the two resulting fragments remained bound by the disulfide bond between Cys53 and Cys165. Oxidation of the single tryptophan resulted in reduced immunologic activity, reduced helical content as measured by circular dichroism below 240 nm, and changes in the near-UV circular dichroic spectrum, each indicating a change in the conformation of the hPL molecule. Nevertheless, this derivative retained 20% of its ability to bind to lactogenic receptors and 40 to 50% of its ability to stimulate N-acetyllactosamine synthetase in vitro. Cleavage at the tryptophan was not complete, but the loss of immunologic and biologic activity was equivalent to the degree of cleavage, indicating that the cleaved derivative was completely inactive. In addition, separation of the cleaved fragments from intact hormone followed by recombination did not generate any immunologic or biologic activity. We conclude that the single tryptophan of hPL is not essential for the biologic activity of hPL. It is likely that the reduced activity associated with modification or cleavage at the tryptophan residue is due to changes in the conformation of the molecule.

Amino Acids↗
PubMed1981

Recombinant hormones from fragments of human growth hormone and human placental lactogen.

Peptide fragments generated by limited plasmin digestion and reduction of human growth hormone (hGH) and human placental lactogen (hPL) were recombined to produce biologically active molecules consisting of the NH2-terminal two-thirds of one hormone molecule linked to the COOH-terminal one-third of the other. Plasmin-cleaved hPL and hGH each consist of an NH2-terminal fragment (1-134) connected to a COOH-terminal fragment (141-191) through a Cys53-Cys165 disulfide bond. The plasmin-cleaved hormones were reduced, the fragments isolated, and then recombined in equimolar quantities to prepared recombinant hormones. On sodium dodecyl sulfate disc gel electrophoresis the recombinants migrated as a single band in the position of native hormone when they were not reduced and as two bands in the positions of the fragments when they were reduced. This indicated that the recombinants had re-formed a disulfide bond. The derivatives were tested for immunologic activity in hPL and hGH radioimmunoassays, for lactogenic and growth-promoting activity by the radioreceptor assays using membranes from mammary gland and liver of lactating rabbits, and for secondary and tertiary structure by circular dichroism measurements in the near and far UV regions. The recombinant with NH2-terminal hGH had hGH immunologic activity, hGH structure and lactogenic and growth-promoting activity, while the hybrid with NH2-terminal hPL had hPL immunologic activity, hPL structure, and lactogenic activity alone. Therefore the immunologic activity, biologic activity, and structure of each of the covalently linked derivatives was characteristic of the hormone's NH2-terminal 1-134 fragment. The COOH-terminal 141-191 sequence maintains overall conformation but appears to have little, if any, role in determining biologic specificity.

Amino Acids↗
PubMed1981

Dyadic interaction in a logical reasoning problem requiring inclusion ability.

This study involved a test of the hypothesis that dyadic performance is superior to the performance of children working alone because children in dyads are able to cooperatively coordinate their different perspectives. A novel task requiring inclusion reasoning was given to children 4--8 years old working in dyads and working alone. Dyadic performance was not superior and correct dyadic solution was frequently based on the incorrect child's compliance with the correct partner's judgment, a finding that is consistent with results of previous studies. Thus, the hypothesis was not supported because children working together did not do better than children working alone, and correct dyadic solutions were sometimes based on compliance rather than on cooperative coordination of perspectives.

Child↗
PubMed1979

Modification of human placental lactogen with plasmin. Preparation and characterization of a modified hormone with increased biologic activity.

To determine the structure needed for the biologic activity of human placental lactogen (hPL), we have cleaved hPL with the proteolytic enzyme plasmin. Plasmin modified hPL (PL-hPL) was purified by gel chromatography. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis before and after reduction showed that cleavage had occurred within the Cys53-Cys165 loop and tryptic peptide maps revealed that a single peptide consisting of residues 135 to 140 had been removed. 5-Dimethylaminonaphthalene-1-sulfonyl end group analysis and digestion with carboxypeptidase B confirmed that cleavage was complete and only the single hexapeptide was removed. In a membrane binding assay for lactogenic activity PL-hPL was 2- to 3-fold more potent than hPL. Using growth hormone receptors from rabbit liver membranes, PL-hPL was also more potent than hPL, but still much less potent than growth hormone. The lactogenic activity of PL-hPL in an in vitro bioassay was 75% above that of unmodified hormone. It is concluded that plasmin cleaves homologous peptides from hPL and growth hormone and that removal of the hexapeptide from hPL results in enhanced biologic activity.

Amino Acids↗
PubMed1979

Preparation of a disulfide-linked dimer of human placental lactogen fragment 1--134 with immunologic and biologic activity.

In order to determine the chemical features of human placental lactogen (hPL) necessary for its biologic activity we prepared the following fragments from the plasmin-cleaved hormone: reduced and alkylated 1--134, reduced and alkylated 141--191, and a 1--134 dimer joined through the single cysteinyl residue at position 53. In a radioimmunoassay using antibodies against native hPL, the two reduced and alkylated fragments produced nonparallel displacement and had less than 1% of the activity of hPL. The ability of reduced and alkylated 1--134 to bind to mammary gland receptors was less than 5% of that of hPL; reduced and alkylated 141--191 showed no detectable activity in the same assay. The 1--134 dimer, in contrast, had 20% of the immunologic activity and 30% of the ability to bind to lactogenic receptors relative to the native hormone. In an in vitro bioassay the lactogenic activity of the 1--134 dimer was equivalent to that of the native hormone. The circular dichroic spectra of hPL, reduced and alkylated 1--134, and 1--134 dimer indicated that the dimer had regained much of the helical content of the native hormone. Antibodies produced to reduced and alkylated 1--134 did not significantly crossreact with either native hPL or 1--134 dimer. From these data we conclude that the information for the lactogenic activity of hPL is contained in the first 134 amino acid residues and that the proper conformation is necessary for its biologic expression.

Amino Acids↗
PubMed1979

Non-verbal and verbal judgements of length invariance by young children.

One hundred and fifty non-conservers in length were assessed for their ability to make a non-verbal judgement of length invariance on a task employing a train-transfer design in which the stimuli were pairs of pencils. Seventy per cent of the children from the group who had to respond to length equality as opposed to inequality made the correct invariance judgement and could, moreover, characterize their choices in invariance language (e.g. 'same size') whilst still failing the standard verbal task in which such phrases were used by the experimenter. This is regarded as supporting the hypothesis that the non-conserver's linguistic difficulty is not with framing the verbal judgement but in interpreting a question which he believes has to be interpreted unidimensionally in such a context of perceptual change.

Child↗
PubMed1978

The covalent structure of bovine liver rhodanese. NH2-terminal sequence and partial structural analysis of tryptic peptides from the citraconylated protein.

Nineteen tryptic peptides produced by cleavage at 18 of the 20 arginyl residues in citraconylated S-carboxymethylcysteinyl-rhodanese have been isolated by a combination of gel filtration and high voltage paper electrophoresis. These Tc fragments account for all of the 293 residues in the parent polypeptide and their partial or complete sequences have been determined by automated and manual Edman degradation. In some cases, sequence analyses were completed by degradation of peptides derived by secondary cleavages of the decitraconylated Tc fragments with trypsin, chymotrypsin, or the protease from Staphylococcus aureus. Automated Edman degradation of intact S-carboxymethylcysteinyl-rhodanese was performed for 60 cycles; the information thus obtained permitted the alignment of seven of the Tc fragments and gave the sequence of the first 79 residues in the polypeptide chain. The Tc peptide at the COOH terminus of rhodanese was placed by virtue of the fact that it contained no arginine. Structural analysis of the Tc peptides provided the sequences surrounding all five of the methionyl residues in the enzyme. One of the methionines was found in a 19-residue Tc fragment which also contained the cysteinyl residue essential for catalysis.

Amino Acid Sequence↗
PubMed1978

The covalent structure of bovine liver rhodanese. Isolation and partial structural analysis of cyanogen bromide fragements and the complete sequence of the enzyme.

Cyanogen bromide fragments from reduced and carboxymethylated rhodanese have been isolated by gel filtration and ion exchange chromatography on columns of Sephadex G-50 and sulfoethyl-Sephadex C-25, respectively. Partial or complete structural analysis of these fragments has permitted the ordering in sequence of all eleven of the nonaligned tryptic peptides from citraconylated, S-carboxymethylcysteinyl-rhodanese and has thus provided the complete covalent structure of the enzyme. Rhodanese is a single polypeptide of 293 residues and the molecule weight calculated from the covalent structural analysis is about 32,900. The cysteinyl residue implicated in the catalytic function of rhodanese is at position 247. In some preparations of the enzyme the NH2-terminal dipeptide Val-His is missing and the sequence begins with the glutamine at position 3. The rhodanese thus obtained contains 291 amino acid residues and possesses full enzymic activity. X-ray crystallographic analysis of rhodanese has shown that the halves of the molecule (Domains I and II) are nearly identical in conformation. Comparative analysis of the sequences in Domains I and II containing residues with conformationally equivalent alpha C atoms has revealed some degree of homology between the halves of the rhodanese polypeptide. Nethertheless, the structural equivalence of the rhodanese domains is reflected much more by their similarity in tertiary structural than by their sequence homology, even when the sequence comparisons are optimized with reference to the crystallographic results.

Amino Acid Sequence↗