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Biomedical subjects

D G Marshall

Publications and source records attributed to D G Marshall.

At least 19 recordsLinked to original sources
PubMed1999

A role for the leucine-responsive regulatory protein and integration host factor in the regulation of the Salmonella plasmid virulence (spv ) locus in Salmonella typhimurium.

The Salmonella plasmid virulence (spv ) genes of Salmonella typhimurium are activated at the level of transcription as the bacteria enter stationary phase in vitro or in response to signals received during intracellular growth. Activation requires the LysR-like transcription factor SpvR and the alternative sigma factor RpoS. In this report, we show by biochemical and genetic analyses that two chromosomally encoded DNA-binding proteins contribute to the control of spv expression. These are the integration host factor (IHF), which binds to DNA sequences upstream of the spvR regulatory gene, and the leucine-responsive regulatory protein (Lrp), which binds to sequences upstream of the spvABCD operon. Under all conditions tested, inactivation of IHF expression reduces the level of spvR transcription by twofold. It also alters the response of the spv regulon to loss of DNA gyrase activity, consistent with a role for IHF in organizing DNA structure in the vicinity of the spvR promoter. Lrp represses spvA gene expression by up to fivefold and Lrp-mediated repression is antagonized by leucine. The Lrp binding site upstream of the spvA gene overlaps one of the binding sites for the positive regulator SpvR, suggesting a mechanism by which Lrp repression is exerted. This is a first demonstration of a role for Lrp in controlling genes that are also subject to intracellular regulation. These data show that the spv virulence genes belong simultaneously to several regulons in the cell, raising the possibility that spv expression can be fine-tuned in response to multiple environmental inputs.

Bacterial Proteins↗
PubMed1999

Lack of a relationship between Lewis antigen expression and cagA, CagA, vacA and VacA status of Irish Helicobacter pylori isolates.

The cagA gene, vacA gene, CagA (cytotoxin-associated gene A product) and VacA (vacuolating cytotoxin) status of a collection of Helicobacter pylori isolates from the geographically distinct Irish population was determined, the potential association of these traits with Lewis (Le) antigen expression was assessed, and the relationship between these bacterial properties and the pathology associated with H. pylori infection was evaluated. Of the 57 isolates, a higher proportion from ulcer than from non-ulcer patients expressed VacA (71% vs. 53%). H. pylori isolates which were cagA-positive were no more significantly associated with peptic ulcers than non-ulcer disease (71% vs. 67%, P = 0.775), nor were CagA-positive isolates (57% vs. 50%, P = 0.783), but 80% of the isolates from duodenal ulcer patients were cagA-positive. Thirty-seven of the 57 isolates were tested for Le antigen expression. No statistically significant relationship (P > 0.05) was found between the occurrence and level of expression of Le(x) or Le(y) and cagA, vacA, or VacA status. This lack of an association in the Irish H. pylori isolates contrasts with that previously reported for predominantly North American isolates, and may be attributable to the adaptation of H. pylori strains with differing attributes to different human populations.

Antigens, Bacterial↗
PubMed1996

Genomic DNA fingerprinting of clinical isolates of Helicobacter pylori using short oligonucleotide probes containing repetitive sequences.

The ability of oligonucleotide probes containing short repetitive sequence motifs to differentiate between isolates of Helicobacter pylori was investigated. Genomic DNA preparations from H. pylori were digested with the restriction enzyme HindIII, electrophoresed in agarose gels and transferred to nylon filters. Five separate oligonucleotide probes were tested for hybridization sequentially to fingerprint the digested DNA from a panel of 29 clinical isolates and one type strain of H. pylori, and their relative discriminatory abilities were assessed. Four probes, (GACA)4, (GT)8, (GTG)5 and (GGAT)4, were each shown to yield highly informative hybridization band profiles allowing differentiation of H. pylori isolates. The DNA fingerprints of individual isolates obtained with each probe were distinct and reproducible. Direct comparison with ribotyping revealed that oligonucleotide fingerprinting had far superior discriminatory power. Computer-assisted similarity analysis of (GGAT)4-generated hybridization profiles of pairwise combinations of H. pylori isolates revealed that there was no correlation between ribotype and oligonucleotide fingerprint patterns. The results of this study demonstrate that oligonucleotide probes containing microsatellite sequences provide a new and powerful tool for isolate discrimination of H. pylori.

DNA Fingerprinting↗
PubMed1995

Molecular analysis of Helicobacter pylori populations in antral biopsies from individual patients using randomly amplified polymorphic DNA (RAPD) fingerprinting.

In the present study, randomly amplified polymorphic DNA (RAPD) fingerprinting has been used to analyse multiple single colony isolates of Helicobacter pylori from antral biopsies in an attempt to ascertain whether or not multiple strains are present in individual patients using single biopsy samples. The RAPD fingerprints derived from single colonies obtained from the same biopsy specimen were in all cases indistinguishable. The previously noted heterogeneity between H. pylori strains from different individuals was confirmed. RAPD fingerprinting, combined with a simple method of template preparation, was shown to be an excellent method for H. pylori strain differentiation. The results of this study indicate that the H. pylori population is homogeneous in individual patients at a single gastric site.

Bacterial Typing Techniques↗
PubMed1995

Recrudescence of Helicobacter pylori after apparently successful eradication: novel application of randomly amplified polymorphic DNA fingerprinting.

The aim of this study was to find out if reinfection or recrudescence accounted for the recurrence of Helicobacter pylori infections after apparent eradication of the bacterium. Three hundred and twenty patients were treated with colloidal bismuth subcitrate (120 mg four times daily for four weeks), metronidazole and tetracycline (400 mg and 500 mg, respectively, thrice daily for the first week). H pylori was eradicated four weeks after the end of treatment as assessed by the rapid urease test, histological examination, Gram staining, and culture. However, the infection recurred in 29 (9.1%) of the patients one year after apparent eradication. Pre and posteradication isolates from five patients were available. DNA was extracted and used for restriction endonuclease analysis with Hind III and Hae III, and for polymerase chain reaction (PCR) based randomly amplified polymorphic DNA fingerprinting with a combination of two 10 nucleotide primers. Sodium dodecyl sulphate polyacrylamide gel electrophoretic analysis was performed also. Randomly amplified polymorphic DNA fingerprinting was unique in that it yielded highly discriminatory fingerprints, which showed that the pretreatment and recurrent isolates obtained from each of the five patients were indistinguishable from one another. This shows that recurrence of H pylori infection is probably caused by recrudescence and that the discriminatory power of randomly amplified polymorphic DNA fingerprinting is a practicable and discriminatory typing scheme for H pylori.

Adult↗
PubMed1993

Preampullary congenital duodenal obstruction in a father and son.

This is the report of an infant seen on June 25, 1960 with preampullary total duodenal obstruction caused by a combined annular pancreas and duodenal stenosis above the ampulla. A gastroduodenostomy was performed. In December 1989, he fathered a 1,700-g boy with preampullary duodenal atresia. A duodeno-duodenostomy was performed successfully by the same pediatric surgeon. Second-generation duodenal obstruction is rare; to our knowledge, there are no other cases.

Adult↗
PubMed1991

Spinal anaesthesia for inguinal hernia repair in high-risk neonates.

To avoid the high incidence of respiratory complications associated with general anaesthesia in premature neonates, 44 spinal anaesthetics for inguinal hernia repair in very low birthweight infants were administered in 47 attempts. Hyperbaric tetracaine with epinephrine 1:200,000 was administered in a dose range of 0.27-1.10 mg.kg-1. Attempted lumbar puncture failed in three infants. In 24 procedures, spinal anaesthesia alone provided satisfactory operating conditions; in 20, supplementary inhalational general anaesthesia or iv ketamine was necessary. Perioperative apnoeic episodes requiring bag/mask assisted ventilation occurred in six infants. In five infants, apnoeic spells occurred in the postoperative period. No infant required tracheal intubation; there was no haemodynamic instability. Twenty-four infants required no postoperative analgesia. Our experience suggests that spinal anaesthesia for inguinal hernia repair in very low birth weight infants reduces but does not eliminate the risk of respiratory instability, and that supplementary anaesthesia is often necessary to provide satisfactory operating conditions.

Anesthesia, Inhalation↗
PubMed1988

Jejunal intussusception: a case report and review.

Jejunal intussusception is a rare condition. In contrast to the typical case of ileocolic intussusception, a "lead point" is commonly found that is usually ectopic gastric mucosa. A review of the literature and a case report is presented.

Female↗
PubMed1987

Leiomyosarcoma of the duodenum.

This is a case report of a large leiomyosarcoma of the duodenum in a 10-year-old boy who weighed only 22 kg. He was successfully treated with a Whipple procedure or pancreatoduodenectomy.

Child↗
PubMed1987

An alternative to an interposition procedure in esophageal atresia.

The suture fistula technique for long gap esophageal atresia with tracheoesophageal fistula (TEF) was described by Shafer and David in 1974. Schullinger in 1982 reported five cases with fistulization occurring in four cases. In the past 2 years, we have used this technique in four infants who ranged from 1,200 to 1,700 g and in one infant who weighed 2,900 g. Successful luminal continuity was established in four of the cases and a temporary fistula in the fifth, but this closed. The latter did require a repeat thoracotomy with resection and end-to-end suture 28 days after the original suture-fistula technique. She is well. In a recent full-term infant this technique was used successfully too. All procedures were done transpleurally. We have found that fistulization usually occurs about the eighth or ninth day. This is apparent when milk, given by gastrostomy, appears in the mouth. To date, one of our children (K.C.) has required an antereflux procedure.

Abnormalities, Multiple↗
PubMed1986

Two boys with four pheochromocytomas each.

Two teenage boys were treated at separate pediatric institutions for four separate pheochromocytomas over the last 15 years. The first operation in each boy was performed between 9 and 11 years of age, after they presented with severe hypertensive encephalopathy. One boy had separate adrenal tumors excised in 1968, and 3 and 11 years later, two more separate new left adrenal pheochromocytomas were again resected. They were not recurrent left adrenal tumors from residual pheochromocytoma-secreting tissue, because no visible tumor tissue was left behind at the completion of each previous operation, and he was clinically well for years between each tumor resection. The pathology was benign pheochromocytoma. He remains well since the last operation in 1979 but has a residual hemiplegia from the first tumor. The family history is negative. The second boy was first operated on in 1976 at age 11 years when two benign pheochromocytomas were removed from around the right renal artery and the left para-aortic area. He remained well for 6 years when he became hypertensive again (this time without encephalopathy), and had a right chest paravertebral pheochromocytoma removed and several weeks later a left adrenal tumor was also removed. He remains well and followed closely. His family history is negative.

Adolescent↗