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Biomedical subjects

J M Foster

Publications and source records attributed to J M Foster.

At least 19 recordsLinked to original sources
PubMed2001

Detection of serum IgG antibodies specific for Wolbachia surface protein in rhesus monkeys infected with Brugia malayi.

The mechanism of lymphedema development in individuals with lymphatic filariasis is presently poorly understood. To investigate whether Wolbachia, symbiotic bacteria living within filarial nematodes, may be involved in disease progression, Wolbachia-specific immune responses were assayed in a group of Brugia malayi-infected rhesus monkeys. Serum IgG antibodies specific for a major Wolbachia surface protein (WSP) were detected in 2 of 12 infected monkeys. It is interesting that both of these monkeys developed lymphedema after becoming amicrofilaremic. WSP-specific antibody responses were temporally associated with increases in antifilarial IgG1 antibodies as well as lymphedema development. These findings suggest that Wolbachia may be important in understanding disease caused by filarial worms.

Animals↗
PubMed2001

Determination of Wolbachia genome size by pulsed-field gel electrophoresis.

Genome sizes of six different Wolbachia strains from insect and nematode hosts have been determined by pulsed-field gel electrophoresis of purified DNA both before and after digestion with rare-cutting restriction endonucleases. Enzymes SmaI, ApaI, AscI, and FseI cleaved the studied Wolbachia strains at a small number of sites and were used for the determination of the genome sizes of wMelPop, wMel, and wMelCS (each 1.36 Mb), wRi (1.66 Mb), wBma (1.1 Mb), and wDim (0.95 Mb). The Wolbachia genomes studied were all much smaller than the genomes of free-living bacteria such as Escherichia coli (4.7 Mb), as is typical for obligate intracellular bacteria. There was considerable genome size variability among Wolbachia strains, especially between the more parasitic A group Wolbachia infections of insects and the mutualistic C and D group infections of nematodes. The studies described here found no evidence for extrachromosomal plasmid DNA in any of the strains examined. They also indicated that the Wolbachia genome is circular.

Chromosomes, Bacterial↗
PubMed2001

Use of random amplified polymorphic DNA PCR to examine epidemiology of Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans from patients with cystic fibrosis.

Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans have been increasingly recognized as a cause of respiratory tract colonization in cystic fibrosis (CF). Although both organisms have been associated with progressive deterioration of pulmonary function, demonstration of causality is lacking. To examine the molecular epidemiology of S. maltophilia and A. xylosoxidans in CF, isolates from patients monitored for up to 2 years were fingerprinted using a PCR-based randomly amplified polymorphic DNA (RAPD-PCR) method. Sixty-one of 69 CF centers screened had 183 S. maltophilia culture-positive patients, and 46 centers had 92 A. xylosoxidans-positive patients. At least one isolate from each patient was genotyped, and patients with > or =10 positive cultures (12 S. maltophilia cultures, 15 A. xylosoxidans cultures) had serial isolates genotyped. In addition, centers with multiple culture-positive patients were examined for evidence of shared clones. There were no instances of shared genotypes among different CF centers. Some patients demonstrated isolates with a single genotype throughout the observation period, and others had intervening or sequential genotypes. At the six centers with multiple S. maltophilia culture-positive patients and the seven centers with multiple A. xylosoxidans-positive patients, there were three and five instances of shared genotypes, respectively. The majority of shared isolates were from pairs who were siblings or otherwise epidemiologically linked. These findings suggest RAPD-PCR typing can distinguish unique CF isolates of S. maltophilia and A. xylosoxidans, person-to-person transmission may occur, there are not a small number of clones infecting CF airways, and patients with long-term colonization may either have a persistent organism or may acquire additional organisms over time.

Alcaligenes↗
PubMed2000

Alosetron, a 5-HT3 receptor antagonist, delays colonic transit in patients with irritable bowel syndrome and healthy volunteers.

BACKGROUND: Alosetron is a potent and selective 5-HT3 receptor antagonist, which has been shown to be beneficial in the treatment of female patients with non-constipated irritable bowel syndrome. AIMS: To investigate the effect of alosetron on whole gut, small bowel and colonic transit in patients with irritable bowel syndrome (Study 1) and healthy volunteers (Study 2). SUBJECTS: Thirteen patients with irritable bowel syndrome and 12 healthy volunteers. METHODS: Both studies were randomized, double-blind, placebo-controlled with a two-way crossover design, in which each subject received alosetron (2 mg b.d. administered orally) or placebo for 8 days. Mean whole gut transit was determined from the excretion of radio-opaque markers; small bowel transit was determined from rise in breath hydrogen after a meal; and colonic transit and segmental transit were evaluated from abdominal X-ray. In addition, colonic transit was calculated by subtracting small bowel transit time from whole gut transit time. RESULTS: Alosetron increased colonic transit time by prolonging left colonic transit in both patients with irritable bowel syndrome and controls. This resulted in a tendency for the whole gut transit to be delayed in irritable bowel syndrome patients (P=0.128), which was confirmed in controls (P=0.047). CONCLUSION: Alosetron delays colonic transit by prolonging left colonic transit. These results add to the body of evidence suggesting that alosetron should have a therapeutic role in patients with non-constipated irritable bowel syndrome.

Adult↗
PubMed2000

Two cDNAs representing alleles of the nitrate reductase gene of potato (Solanum tuberosum L. cv. Desirée): sequence analysis, genomic organization and expression.

Two, different, full-length cDNAs, StNR2 and StNR3, of 3049 and 3066 nucleotides, respectively, were isolated from a Solanum tuberosum L. cv. Desirée leaf cDNA library by an RT-PCR approach. Conceptual translation of the longest open reading frame of each cDNA showed that they could encode a protein of 911 amino acids in each case with an M(r) of 102.6 and 102.5 kDa, respectively, and with 99.7% identity with each other. The cDNAs have a high degree of sequence similarity with all higher plant nitrate reductases (NRs) and possess structural characteristics expected of NADH-NR proteins, consistent with enzyme activity data. Southern analysis of genomic DNA suggested the presence of a single NR gene in the potato genome whilst studies using the mapping population F1840, and the full-length StNR2 cDNA as hybridization probe, identified a single NR locus within the potato genome that is located on chromosome XI. The two cDNAs identified here are probably derived from two transcribing alleles of this single gene. Distribution of total NR transcript and of NADH-NR activity, in different organs of compost-grown plants, depended on the level of nitrate supplied: at low nitrate level transcript and activity were detected only in leaf and stem tissue whilst at high nitrate level they could also be detected in root and stolon. An RT-PCR approach was used to differentiate between the transcripts derived from the two identified alleles and to show that the pattern of transcription of the two identified alleles of the potato nia gene, in the organs studied, is the same.

Amino Acid Sequence↗
PubMed1999

Contextual effects of transforming growth factor beta on the tumorigenicity of human colon carcinoma cells.

Transforming growth factor betas (TGF-betas) are a growth factor family with negative autocrine growth functions for most epithelial cells including colon carcinoma cell lines. Both type I (RI) and type II (RII) transmembrane TGF-beta receptors have been shown to be indispensable for TGF-beta-mediated cell growth regulation. Previous studies using different model systems have shown that both overexpression of TGF-beta1 and transfection of antisense TGF-beta1 to reduce TGF-beta1 expression could lead to increased tumorigenicity. These results are seemingly contradictory and suggest that effects of TGF-beta modulation on malignant properties of cancer cells may be contextual. This study addresses this issue using human colon carcinoma cells (CBS and FET) to determine the effects of modulation of the various components of the TGF-beta system on in vitro and in vivo growth properties in two independent isogenic models of colon carcinoma. Cells were stably transfected with a tetracycline-repressible RII expression vector (CBS4-RII), a tetracycline-repressible expression vector containing a truncated RII cDNA lacking the serine/threonine kinase domain (CBS4-deltaRII and FET6-deltaRII), or with a vector containing the TGF-beta1 cDNA (CBS4-beta1S and FET-beta1S). Expression of the truncated RII reduced TGF-beta sensitivity, whereas overexpression of RII increased TGF-beta sensitivity. TGF-beta overexpression did not affect TGF-beta response. In vivo tumorigenicity assays revealed that CBS4-RII cells had lower tumorigenicity than control cells, whereas CBS4-deltaRII and CBS4-beta1S had higher tumorigenicity than controls. The CBS4 cells are poorly tumorigenic in athymic mice, and the wild-type FET6 cells are nontumorigenic. FET6-deltaRII cells formed rapidly growing tumors, and FET-beta1S cells also formed tumors. These data illustrate the paradoxical tumor-promoting and -suppressing effects of TGF-beta signaling activity in two isogenic model systems from human colon carcinomas, thus demonstrating that the effects of modulation of TGF-beta expression or TGF-beta signaling capability affects malignancy in a contextual manner.

Animals↗
PubMed1999

Altered oesophageal motility following the administration of the 5-HT1 agonist, sumatriptan.

BACKGROUND: The 5-HT1 agonist sumatriptan, used in the treatment of migraine, can cause chest pain. AIM: To investigate the effect of a therapeutic dose of sumatriptan (6 mg s.c.) on oesophageal motility. METHODS: In 16 normal healthy subjects aged 19-32 years (9 males), the manometric response of the lower oesophageal sphincter (sleeve sensor), oesophageal body (four sites), stomach and pharynx (to register swallows) to 5 mL water swallows was assessed before and after a subcutaneous injection of either sumatriptan (6 mg) or saline control. Symptoms and ECGs were also monitored. RESULTS: Sumatriptan 6 mg s.c. altered oesophageal motility in all subjects. This was reflected by a significant increase in the amplitude of oesophageal body contractions (change from pre- to 1 h post-injection: sumatriptan 9.9 (2.8, 17.1) mmHg vs. placebo -0.8 (-4.2, 2.6) mmHg, difference 10.8 (4.4, 17.1) mmHg; P=0.003) and a transient increase in lower oesophageal sphincter pressure (change from pre- to 5 min post-injection: sumatriptan 10.9 (5.2, 16.6) mmHg vs. placebo 5.1 (1.8, 8.4) mmHg, difference 5.8 (-0.7, 12.3) mmHg; P=0.08). Sumatriptan had no effect on the velocity of propagation of oesophageal contractions (change from pre- to 1 h post-injection: sumatriptan -0.1 (-0.3, 0.1) cm/s vs. placebo -0.1 (-0.3, 0.0) cm/s, difference 0.1 (-0.1, 0.2) cm/s; P = 0.40). One subject experienced chest symptoms following sumatriptan and, although motility was altered, this did not reach pathological levels. No ECG abnormalities were observed. CONCLUSION: Sumatriptan (6 mg s.c.) significantly alters oesophageal motor function without affecting the ECG. It is therefore possible that sumatriptan-induced chest symptoms may have an oesophageal origin. The evaluation of similar therapeutic agents for migraine on oesophageal function may be justified.

Adult↗
PubMed1999

Chemiluminescent detection of sequential DNA hybridizations to high-density, filter-arrayed cDNA libraries: a subtraction method for novel gene discovery.

A chemiluminescent approach for sequential DNA hybridizations to high-density filter arrays of cDNAs, using a biotin-based random priming method followed by a streptavidin/alkaline phosphatase/CDP-Star detection protocol, is presented. The method has been applied to the Brugia malayi genome project, wherein cDNA libraries, cosmid and bacterial artificial chromosome (BAC) libraries have been gridded at high density onto nylon filters for subsequent analysis by hybridization. Individual probes and pools of rRNA probes, ribosomal protein probes and expressed sequence tag probes show correct specificity and high signal-to-noise ratios even after ten rounds of hybridization, detection, stripping of the probes from the membranes and rehybridization with additional probe sets. This approach provides a subtraction method that leads to a reduction in redundant DNA sequencing, thus increasing the rate of novel gene discovery. The method is also applicable for detecting target sequences, which are present in one or only a few copies per cell; it has proven useful for physical mapping of BAC and cosmid high-density filter arrays, wherein multiple probes have been hybridized at one time (multiplexed) and subsequently "deplexed" into individual components for specific probe localizations.

Animals↗
PubMed1998

Pediatric anesthesia and postoperative analgesia.

Children are not "small adults," particularly when it comes to anesthesia and pain management. The psychological and physiologic uniqueness of children must not be forgotten. Cooperation and communication between the anesthesiologist, surgeon, and pediatrician are essential for successful anesthesia and pain management. Pediatric anesthesiologists involved in the perioperative management of infants and children are very much a part of the "continuity of care" concept.

Adult↗
PubMed1997

Nucleotide sequence of a Drosophila melanogaster cDNA encoding a calnexin homologue.

A cDNA which encodes a calnexin (Cnx)-like protein from Drosophila melanogaster has been characterized. The deduced amino acid sequence shares several regions of homology with Cnx from other sources with two conserved motifs each repeated four times. The gene was found to be transcribed in various tissues and at all developmental stages. We have mapped the gene at chromosomal position 99A and we have also mapped the related gene coding for Drosophila calreticulin at 85E.

Amino Acid Sequence↗
PubMed1997

The soluble alpha-mannosidases of Drosophila melanogaster.

The alpha-mannosidases are implicated in both the catabolism of carbohydrates and the N-linked glycosylation pathway in insects, but little is known of the biochemistry of these glycosidases. In order to study the soluble alpha-mannosidases of Drosophila melanogaster we have used artificial fluorogenic substrates for detection of activity in situ following non-denaturing gel electrophoresis. This approach also permitted examination of the mannosidases present in different tissues and the sensitivity of the enzymes to known mannosidase inhibitors. Fluorogenic substrates were also used to determine the pH optima of partly purified mannosidases. We report that D. melanogaster contains several soluble alpha-mannosidase activities. Acidic mannosidases were detected in the gut, fat body and haemolymph of third-instar larvae. The major activity detected in larval guts was a neutral mannosidase presumed to be involved in digestion.

1-Deoxynojirimycin↗
PubMed1996

Effect of insect-growth-disrupting amines and amides on Schistosoma mansoni in vitro.

A series of nonsteroidal alkylamines and alkylamides, which apparently inhibit phytosterol dealkylation in insects and free-living nematodes, as well as steps in the ecdysteroid biosynthetic pathway of insects, are also known to affect growth and development of animal-parasitic nematodes. The effect of these compounds on the motility, pairing, and viability of the trematode, Schistosoma mansoni, maintained in vitro was examined by incorporating the potential inhibitors into the medium employed for parasite culture. The alkylamines were more active than their amide counterparts, killing all parasites within 18 hr when tested at 25 parts per million. At lower concentrations, reductions in schistosome pairing and motility were observed. The functional group of the amine compounds influenced the schistosomicidal activity, with N-ethylamines being more effective than N,N-dimethylamines of identical carbon chain-length. Of all the compounds tested, N-ethyldodecanamine appeared to be the most promising schistosomicidal agent, killing all parasites within 22 hr at 10 parts per million and preventing parasite pairing at 3 parts per million.

Amides↗
PubMed1995

Cloning and sequence analysis of GmII, a Drosophila melanogaster homologue of the cDNA encoding murine Golgi alpha-mannosidase II.

Using the murine cDNA that encodes Golgi alpha-mannosidase II (GlcNAc transferase I-dependent alpha 1,3[alpha 1,6] mannosidase; EC 3.2.1.114) as a probe to screen a cDNA library made from Drosophila melanogaster (Dm) embryos, we have isolated GmII, the Dm sequence homologue. The 3926-bp cDNA has an open reading frame of 3327 bp and predicts a polypeptide of approx. 127 kDa, a mass similar to that of the murine protein. The deduced mouse and Dm amino acid (aa) sequences share extensive similarity across their entire lengths and are both type-II transmembrane (TM) proteins with short cytoplasmic tails, single TM domains and large hydrophilic C-terminal domains. A region of approx. 200 aa, within the C-terminal domain, has considerable similarity to a corresponding region from several other alpha-mannosidases. GmII has been localized to a single site (85D14-18) on the right arm of chromosome 3.

Amino Acid Sequence↗
PubMed1995

Correlation of pain with temperature and blood-flow changes in the lower limb following chemical lumbar sympathectomy in reflex sympathetic dystrophy. A case report.

Temperature and microcirculatory blood flow studies have been measured before and after chemical sympathectomy in a patient with reflex sympathetic dystrophy of the left leg present for at least three years following surgery for glomus tumour. Normalisation of temperature and blood flow was associated with the relief of pain, present initially when the limb was hypothermic and vasoconstricted and recurring when the limb was hyperthermic and vasodilated. It is possible that such objective measurement may be used to determine the optimal management of RSD.

Aged↗
PubMed1994

Is chest pain after sumatriptan oesophageal in origin?

3-5% of patients taking the 5HT1D agonist sumatriptan for migraine have chest discomfort, suggesting a cardiac origin. We have investigated an alternative explanation of an oesophageal cause in 24 volunteers after the subcutaneous administration of a supratherapeutic dose of sumatriptan (16 mg) or placebo in a randomised, double-blind crossover study. Sumatriptan did not alter the electrocardiogram but increased the amplitude (p < 0.001) and duration (p < 0.001) of oesophageal contractions without affecting velocity of propagation. Clinically abnormal motility was also increased (p = 0.001), and was more common in the 5 subjects with chest pain after sumatriptan. The effect of sumatriptan on oesophageal function provides an alternative explanation for the chest symptoms.

Adult↗