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Biomedical subjects

M Hodges

Publications and source records attributed to M Hodges.

At least 55 records · Page 3Linked to original sources
PubMed1995

Purification and characterization of a fully active recombinant tobacco cytosolic NADP-dependent isocitrate dehydrogenase in Escherichia coli: evidence for a role for the N-terminal region in enzyme activity.

The recently isolated full-length NADP-dependent isocitrate dehydrogenase (ICDH) cDNA encoding the tobacco cytosolic isoenzyme has been cloned into the expression vector pET8c and used to transform Escherichia coli strain BL21 (DE3). The recombinant protein was purified to electrophoretic homogeneity and used to raise polyclonal antibodies. Its kinetic properties were found to be identical to those of the cytosolic ICDH isoenzyme purified from tobacco cell cultures. The recombinant and the endogenous bacterial ICDH could be easily distinguished by their different behaviors during anion-exchange column chromatography and immunological response. An incomplete ICDH-encoding cDNA clone, encoding a protein lacking the first 36 amino acids at the N-terminus, was cloned into the expression vector pKK233-2 and used to transform ICDH-lacking E. coli cells (strain 2004). The truncated, recombinant ICDH produced by the bacteria was found to be inactive.

Amino Acid Sequence↗
PubMed1995

Chlamydomonas reinhardtii thioredoxins: structure of the genes coding for the chloroplastic m and cytosolic h isoforms; expression in Escherichia coli of the recombinant proteins, purification and biochemical properties.

Based on known amino acid sequences, probes have been generated by PCR and used for the subsequent isolation of cDNAs and genes coding for two thioredoxins (m and h) of Chlamydomonas reinhardtii. Thioredoxin m, a chloroplastic protein, is encoded as a preprotein of 140 amino acids (15,101 Da) containing a transit peptide of 34 amino acids with a very high content of Ala and Arg residues. The sequence for thioredoxin h codes for a 113 amino acid protein with a molecular mass of 11,817 Da and no signal sequence. The thioredoxin m gene contains a single intron and seems to be more archaic in structure than the thioredoxin h gene, which is split into 4 exons. The cDNA sequences encoding C. reinhardtii thioredoxins m and h have been integrated into the pET-3d expression vector, which permits efficient production of proteins in Escherichia coli cells. A high expression level of recombinant thioredoxins was obtained (up to 50 mg/l culture). This has allowed us to study the biochemical/biophysical properties of the two recombinant proteins. Interestingly, while the m-type thioredoxin was found to have characteristics very close to the ones of prokaryotic thioredoxins, the h-type thioredoxin was quite different with respect to its kinetic behaviour and, most strikingly, its heat denaturation properties.

Amino Acid Sequence↗
PubMed1995

MELAS syndrome.

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Adult↗
PubMed1994

Purification and characterization of pea thioredoxin f expressed in Escherichia coli.

The recently cloned cDNA for pea chloroplast thioredoxin f was used to produce, by PCR, a fragment coding for a protein lacking the transit peptide. This cDNA fragment was subcloned into a pET expression vector and used to transform E. coli cells. After induction with IPTG the transformed cells produce the protein, mainly in the soluble fraction of the broken cells. The recombinant thioredoxin f has been purified and used to raise antibodies and analysed for activity. The antibodies appear to be specific towards thioredoxin f and do not recognize other types of thioredoxin. The recombinant protein could activate two chloroplastic enzymes, namely NADP-dependent malate dehydrogenase (NADP-MDH) and fructose 1,6-bisphosphatase (FBPase), both using dithiothreitol as a chemical reductant and in a light-reconstituted/thylakoid assay. Recombinant pea thioredoxin f turned out to be an excellent catalyst for NADP-MDH activation, being the more efficient than a recombinant m-type thioredoxin of Chlamydomonas reinhardtii and the thioredoxin of E. coli. At the concentrations of thioredoxin used in the target enzyme activation assays only the recombinant thioredoxin f activated the FBPase.

Amino Acid Sequence↗
PubMed1994

Use of whole-gut lavage to measure intestinal immunity in healthy Sierra Leonean children.

In view of the potential roles of intestinal immunodeficiency and hypersensitivity in the infection/diarrhea/malnutrition cycle, we need a safe and ethical method to study intestinal immunity of children in the developing world. Work in adults has shown that the fluid obtained by whole-gut lavage (WGLF), essentially a gut perfusate, can be used to assess intestinal immunity, inflammation, and gut losses of protein and blood. Gut lavage was successfully performed in 24 of 25 "normal" children aged 6-9 years, from Freetown, Sierra Leone, with parental informed consent. WGLF was treated with protease inhibitors, stored at -20 degrees C, and transferred to Edinburgh for laboratory studies. These showed that no child had occult blood loss but four had evidence of protein-losing enteropathy. Compared with values for Scottish adults, WGLF from the Sierra Leonean children had significantly higher concentrations of IgA and IgM and of IgA and IgM antibodies to dietary antigens and to Salmonella typhi lipopolysaccharide. In three children, very low levels of IgA and IgA antibody were present: Two of these were the only cases with detectable sIL2R in lavage fluid, indirect evidence of intestinal T cell activation; tumor necrosis factor was not detectable. Substantial information on childrens' intestinal immunity can be obtained by the method described.

Antibodies, Bacterial↗
PubMed1993

Diarrhoeal disease in early childhood: experiences from Sierra Leone.

In the Freetown area of Sierra Leone, the proportion of children under five years of age dying from diarrhoea-associated conditions has decreased since the 1970s from 4% to 3%. This reduction relates to children between 12 months and 5 years; deaths associated with diarrhoeal disease in infancy do not appear to have decreased significantly. Currently, 2% of children die in infancy and a further 1% before their fifth birthday from diarrhoeal diseases. Thirty-one percent of short-term growth-faltering in children under five years of age is attributed to diarrhoeal disease. Reasons for improvement in mortality may include the implementation of a National Diarrhoeal Diseases Control Programme and improved case management; some 55% of cases of acute diarrhoea in Freetown now receive oral rehydration therapy. Morbidity and mortality are influenced by the seasons. This is likely to be related to the fact that the nutritional status of children shows a significant deterioration in the early rainy season. At this time incidence of severe diarrhoea warranting hospital admission and diarrhoea mortality rates in hospital and at a Rehydration Center increased significantly. On the other hand, the presentation of dehydrating diarrhoea is greatest in the driest months of the year. Progress in the rural areas of Sierra Leone may not have been so evident although 60% of the population now have access to primary health units within 4 miles and efforts to increase host resistance have included the measles immunization programme which currently protects 60% of under-fives nation-wide. Efforts to reduce the transmission of pathogens have meant increasing access to safe water to 22% and to improved sanitation to 35% in rural areas of Sierra Leone. The sustainable prevention and control of diarrhoeal diseases in developing countries depends also upon increasing levels of adult literacy especially of women.

Child, Preschool↗
PubMed1992

The premature ventricular complex as a diagnostic aid.

Premature ventricular complexes (PVCs) can provide clues to the physical or electrocardiographic diagnosis through the associated compensatory pause, the break in the regularity of the rhythm, or the morphology of the PVC itself. A PVC may allow visualization of the P wave or of atrial flutter waves that would otherwise be obscured in the electrocardiogram. It can also be useful in distinguishing an S3 gallop from an S4 gallop. The compensatory pause that follows a PVC may allow normal conduction of the next QRS complex in a patient with a rate-dependent intraventricular conduction defect, and this normalized QRS complex may contain important diagnostic findings. A PVC can also reveal a myocardial infarct pattern when the sinus complex fails to do so. Although the need to treat PVCs is currently being de-emphasized, their diagnostic utility should not be overlooked.

Atrial Flutter↗
PubMed1992

Isolation of a cDNA fragment coding for Chlamydomonas reinhardtii ferredoxin and expression of the recombinant protein in Escherichia coli.

A cDNA clone coding for mature C. reinhardtii ferredoxin has been isolated from a cDNA library using PCR and two oligonucleotide primers based on the N- and C-termini of the protein's amino acid sequence. The nucleotidic sequence of the PCR fragment (299 bp) agreed well with the amino acid sequence since a single conservative substitution (Thr-7 to Ser) could be deduced. The PCR fragment was inserted into the expression vector pTrc 99A, using the incorporated NcoI and BamHI restriction sites and the construction used to transform E. coli (DH5 alpha F'). After subsequent large scale expression and purification of the recombinant protein, biochemical and biophysical analysis have indicated that the product isolated from E. coli is homologous to native ferredoxin isolated from green algae.

Amino Acid Sequence↗
PubMed1991

Pirmenol: an antiarrhythmic drug with unique electrocardiographic features--a double-blind placebo-controlled comparison with quinidine.

Previous reports have stated that pirmenol is a Class IA antiarrhythmic drug that prolongs the QT interval, but did not use computerized electrocardiography. We randomized 18 patients with frequent ventricular ectopic depolarizations to pirmenol (8 patients) or quinidine (10 patients). Pirmenol was effective and tolerated for suppression of arrhythmia in all 7 patients treated (1 patient withdrew for personal reasons) but quinidine was effective and tolerated for 4 weeks in only 5 of 10 patients (p less than 0.05). Using computerized 12-lead electrocardiography, the mean change in PR interval from placebo to treatment was 5 +/- 18 ms for quinidine and 5 +/- 11 ms for pirmenol (p = NS). The mean change in QRS interval was 5 +/- 14 ms for quinidine and 10 +/- 5 ms for pirmenol (p = NS). The mean change in QT interval was 46 +/- 30 ms for quinidine and 8 +/- 9 ms for pirmenol (p less than 0.01) and the mean change in JT interval was 41 +/- 36 ms for quinidine and -2 +/- 10 ms for pirmenol (p less than 0.01). After the double-blind phase, 4 quinidine patients had computerized electrocardiographic intervals measured on pirmenol; the above findings were confirmed. These electrocardiographic features of pirmenol clearly distinguish it from quinidine, the prototype Class IA drug. However, pirmenol has minimal effect on the PR and QRS intervals, and thus does not appear to be a Class IC drug either. Although its electrocardiographic features are closest to Class IB, its electrophysiology in isolated cells and its antiarrhythmic and side effect profile are atypical for a IB agent.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1990

The ATP-dependent post translational modification of ferredoxin: NADP+ oxidoreductase.

Incubation of thylakoids with purified FNR and [32P]ATP led to the incorporation of phosphate into the FNR. In the absence of added FNR, 32P-labelled FNR could be detected associated with the thylakoids. An amino-acid analysis showed that in the dark, the FNR could be phosphorylated on a serine residue. In the presence of thylakoids, the FNR contained a threonine phosphate which was associated with a light-dependent reaction. The physiological function of this phosphorylation is not clear. Some modifications in NADP(+)-dependent photosystem I (PSI) activity and FNR-membrane association have been observed on the addition of ATP. Whether these changes are linked to the phosphorylation of the FNR remain to be fully elucidated.

Adenosine Triphosphate↗
PubMed1990

Antiarrhythmic drug therapy for suppression of ventricular arrhythmia: experience with 122 patients treated for two years.

Although there are many reports of the short-term effectiveness of antiarrhythmic drugs for suppression of ventricular ectopic depolarizations, there are less data available on the long-term use of these drugs. We treated 122 patients for up to 2 years with antiarrhythmic drugs for suppression of frequent ventricular ectopic depolarizations. The percent suppression of ventricular ectopic depolarizations and nonsustained ventricular tachycardia for each drug was determined at 1, 3, 6, 12, 18, and 24 months of therapy. Among 33 patients treated with flecainide, the mean suppression of ventricular ectopic depolarizations (average of all data during 24 months) was 93 +/- 17% and of nonsustained ventricular tachycardia was 97 +/- 7%. In 27 patients treated with encainide, the mean suppression of ventricular ectopic depolarizations was 88 +/- 18% and of ventricular tachycardia was 95 +/- 16%. Among 26 patients treated with propafenone, the mean suppression of ventricular ectopic depolarizations was 77 +/- 32% and of ventricular tachycardia was 93 +/- 15%. For the 20 patients treated with moricizine, the mean suppression of ventricular ectopic depolarizations was 62 +/- 35% and of ventricular tachycardia was 90 +/- 14%. Among 16 patients treated with amiodarone, the mean suppression of ventricular ectopic depolarizations was 92 +/- 14% and of nonsustained ventricular tachycardia was 99 +/- 3%. In 54 of the 122 patients (44%), the study drug was stopped during 2 years of therapy because of death (2 sudden, 2 unwitnessed and 6 noncardiac), side effects (21 patients), lack or of loss of efficacy (13 patients), and noncompliance (10 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗