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Biomedical subjects

A Lee

Publications and source records attributed to A Lee.

At least 541 records · Page 30Linked to original sources
PubMed1993

Helicobacter pylori infection within families.

Although H. pylori is now well established as the aetiological agent of acute or chronic gastritis and a predisposing factor in peptic ulceration knowledge regarding the transmission of this organism is unclear. The aim of this study was to examine the prevalence of H. pylori infection in the family members of index children infected with this organism and to examine the role of ethnic background and the relationship of hepatitis A infection to H. pylori infection. The H. pylori status of three groups of subjects, the family members of 21 children shown by endoscopical and histological examination to be infected with H. pylori, the family members of 17 children who had been the index case in a hepatitis study and a control group of Australian blood donors and children were examined using an IgG ELISA. The results of this study showed an increased prevalence of H. pylori infection to exist in the family members of index children infected with H. pylori compared with the family members of children not infected with H. pylori and an age matched blood donor control group. This increased prevalence of H. pylori infection was not dependent on ethnic background and appeared to be unrelated to the hepatitis A status of subjects. These results strongly support the view that transmission of H. pylori is person to person and that transmission may not be the faecal oral route.

Adolescent↗
PubMed1993

Immunisation against gastric infection with Helicobacter species: first step in the prophylaxis of gastric cancer?

The discovery of the gastric bacterium, Helicobacter pylori and the demonstration of its role in the pathogenesis of gastroduodenal disease, has been one of the major microbiological advances in the last decade. Recent demonstration of long term infection with this bacterium as a risk factor in gastric carcinoma suggests that intervention in a disease of major morbidity and mortality is possible. Using a model of Helicobacter infection in mice it has been shown that oral immunisation with a sonicate of Helicobacter felis plus the adjuvant cholera toxin results in protection against an oral challenge with large numbers of viable bacteria. The success of the immunising regimen has been shown to correlate with the development of local immunity. Formulation of equivalent safe vaccines of H. pylori will make possible the immunisation of children in countries such as China, Japan and Columbia and so prevent the establishment of long term inflammation and thus significantly reduce the incidence of gastric cancer in those societies. This animal model is proposed as a major tool in the development of effective oral immunisation.

Animals↗
PubMed1993

The synthesis of three 4-substituted benzo[b]thiophene-2-carboxamidines as potent and selective inhibitors of urokinase.

Efficient synthesis of structurally novel 4-substituted benzo[b]thiophene-2-carboxamidines 1-3, which selectively inhibit urokinase-type plasminogen activator (uPA) with IC50 values of 70-320 nM, are described. The key intermediate, methyl 4-iodobenzo[b]thiophene-2-carboxylate (7), is prepared from 3-fluoroiodobenzene in two steps in 70% overall yield via fluorine-directed metalation/formylation and subsequent thiophene annulation. Amidination of ester 7 gives the 320 nM inhibitor 1. Palladium-catalyzed arylacetylene and vinyl stannane couplings with ester 7 or 4-iodobenzo[b]thiophene-2-carbonitrile (16, derived from 7), respectively, followed by amidination leads to the more potent inhibitors 2 (IC50 = 133 nM) and 3 (IC50 = 70 nM). These compounds represent an important new class of synthetic uPA inhibitors, with carboxamidine 3 being the most potent selective inhibitor currently described in the literature.

Amidines↗
PubMed1993

[15 years vaginal delivery in post-cesarean status].

In a retrospective study covering a period of 15 years (1976-1991), we investigated 673 births after previous caesarean section compared to a matched pair group. During the observation period, an increase of vaginal delivery after previous caesarean section occurred. This decrease in resection rate (first five years period: 59%, 60% in the period of 1981-1985 and 42% within the last five years) could be achieved mainly in births after only one previous caesarean section. In patients with more than one previous caesarean section, the resection rate remained almost stable at 95%. The rate of complication was low in our study group, especially, if compared to studies in the USA. Three uterine ruptures with one maternal death occurred during the entire observation period. No correlation of the complication rate with an increase of vaginal delivery was observed. The more conservative obstetrical management had no negative impact on foetal outcome.

Apgar Score↗
PubMed1993

An uncultured gastric spiral organism is a newly identified Helicobacter in humans.

"Gastrospirillum hominis" is an uncultivated spiral bacterium in human gastric mucosa that is larger and more tightly coiled than Helicobacter pylori. In an attempt to determine if this organism is a new species of Helicobacter, its 16S rRNA gene was cloned and sequenced. Gastric mucosa from 2 patients infected with "Gastrospirillum hominis" was fed to specific pathogen-free mice. Electron microscopy of gastric tissue confirmed that the mice became colonized with "Gastrospirillum hominis." The 16S rRNA gene from bacterial target sequences was amplified directly from mouse stomach tissue by the polymerase chain reaction (PCR), cloned into Escherichia coli, and sequenced. Both fragments were 16S rRNA genes from the Helicobacter genus that were most closely related to Helicobacter felis. "Gastrospirillum hominis" is probably a newly recognized Helicobacter infection in humans. Because this is the only Helicobacter organism that infects both humans and small animals, it may be particularly suited for studies of pathogenesis.

Adult↗
PubMed1993

Diagnosis of major chromosome aneuploidies in human preimplantation embryos.

A short fluorescence in-situ hybridization (FISH) procedure using fluorochrome and digoxigenin labelled DNA probes was developed for application in human preimplantation embryos in order to analyse the five chromosomes most involved in human aneuploidy (X, Y, 18, 13 and 21). The chromosomes were fluorescent-stained and detected simultaneously in 157 blastomeres from 30 human embryos. Successful FISH analysis was achieved in 93% of the blastomeres. Aberrations for these chromosomes were found in 70% of abnormally developing monospermic embryos. The majority of normally developing monospermic embryos obtained from older patients were also chromosomally abnormal. By analysing all or most of the cells from these embryos, true mosaicism was distinguished from technique failure. Mosaic embryos, polyploid embryos with ploidies as high as 8n, haploid embryos, embryos monosomic for 13/21 and for X, and embryos trisomic for 13/21 and 18, were common in abnormally developing embryos. In contrast, aneuploidy was the main chromosome abnormality found in normally developing monospermic embryos.

Adult↗
PubMed1993

Helicobacter pylori infection in children: potential clues to pathogenesis.

Children (227) undergoing endoscopy for upper gastrointestinal symptoms were investigated for the presence of Helicobacter pylori infection. The histological response to H. pylori infection and the presence of antral nodularity and peptic ulceration were noted. Symptomatic adults (258) undergoing endoscopy were also investigated for the presence of nodularity. H. pylori infection was detected histologically in 32 of 227 (14.1%) children. Of those children infected with H. pylori, half (50%) had antral nodular gastritis. Of 139 H. pylori-positive adults 22 (15.8%) showed nodularity. The active component of the histological response was found to be minimal or lacking in the majority of children infected with H. pylori. Twelve of the 227 children (5.3%) had peptic ulcer disease. Of these, nine were duodenal and three gastric ulcers. Of the nine children with duodenal ulceration three (33%) were infected with H. pylori. As a result of this study we conclude that (a) although antral nodularity occurs more frequently in children it is not exclusive to childhood, (b) the polymorphonuclear response in children is less than that reported in adults, and (c) peptic ulcer disease is rare in children and the present study would suggest that in children it is less frequently associated with H. pylori infection than in adults.

Acute Disease↗
PubMed1993

The effect of acidified glucose nutrient solution on preservation of platelet concentrate.

The preservation effect of a new platelet solution--acidified glucose nutrient solution (AGN)--was tested by adding AGN to pooled platelet rich plasma (PRP) prior to preparation of platelet concentrates (PC). Each PRP unit was prepared from a unit of whole blood and four PRP of the same blood group were pooled in 400 ml volume PVC bags. Equal aliquots of each pooled PRP were made prior to preparation of PC. AGN was added to one aliquot and nothing was added to the control aliquot. Equal volume and concentration PC were then prepared and the PC were further aliquoted for storage at 22 degrees C. After five days, the parameters of platelet count, pH, aggregability and hypotonic shock response (HSR) for PC preserved in AGN plasma were better than those of the controls preserved in normal ACD plasma. The aggregability and HSR of AGN platelet concentrates recovered to baseline after two h of incubation with fresh plasma. The results of electron microscopy show that platelets preserved in AGN have less changes in morphology. The results of our work suggest that the preservation effect of AGN on PC is similar to the effect of using second generation containers or preparation of platelets from thrombocytapheresis.

Blood Platelets↗
PubMed1993

Knowledge and compliance with medications in South East Asian refugees.

We evaluated knowledge about prescribed medications and compliance with taking those medications in 96 South East Asian refugees of different ethnic backgrounds seen in a primary care clinic. Two hundred and thirty (88%) of 262 prescribed medications were currently being taken by the patients. Although 97% of the medications were either named or described correctly, the correct rationale for taking the medication was known for only 79% and the correct dosage regimen for only 63%. Thirty-two (33%) of the 96 patients were not taking one or more of their prescribed medications, 17 (18%) were taking one or more medications not prescribed, 5 (5%) were taking duplicate forms of the same medication, and 4 (4%) were taking a medication that had been discontinued by the clinic provider. Seventy-two (75%) patients were taking one or more medications at an incorrect dose. Only 12 (12%) patients were fully compliant with all prescribed medications. We conclude that knowledge about and compliance with medications is a major problem among South East Asian patients attending a primary care refugee clinic.

Asia, Southeastern↗
PubMed1993

Neonatal alloimmune thrombocytopenia. A case report and a review of the literature.

A 32-year-old woman in her third pregnancy underwent fetal blood sampling because of a previous child with neonatal thrombocytopenia. At 33 weeks' gestation, fetal thrombocytopenia was diagnosed. Treatment was instituted antenatally with serial fetal platelet transfusions and corticosteroid therapy. Delivery was by Caesarean section at 37 weeks' gestation. Neonatal treatment included further platelet transfusion and immunoglobulin infusion. Recovery of the neonate was complete on discharge from hospital 10 days after birth. The aetiology, diagnosis, clinical presentations and therapeutic options in cases of alloimmune thrombocytopenia are discussed.

Adult↗
PubMed1993

A double-blind study of L-threonine in patients with spinal spasticity.

We conducted a double-blind, placebo-controlled, crossover study of oral L-threonine at 6 g/day in patients with spinal spasticity. Muscle tone from selected leg muscles, measured by the Ashworth Scale, was the principal measure of spasticity and was evaluated before and at the end of each treatment period. A 10% reduction in Ashworth score was regarded as a positive response to a treatment. The results were analyzed sequentially, patients being classified as threonine-responders, placebo-responders or non-responders (those who responded to both treatments by either less or greater than 10%) and a level of significance of p = 0.05 was chosen. The trial concluded in favour of L-threonine after 33 patients. Side-effects were minimal. L-threonine has a modest but definite antispastic effect, and its possible role in modifying spinal glycinergic transmission is discussed.

Adolescent↗
PubMed1993

Local and systemic immune responses in murine Helicobacter felis active chronic gastritis.

Helicobacter felis inoculated per os into germfree mice and their conventional non-germfree counterparts caused a persistent chronic gastritis of approximately 1 year in duration. Mononuclear leukocytes were the predominant inflammatory cell throughout the study, although polymorphonuclear cell infiltrates were detected as well. Immunohistochemical analyses of gastric mucosa from H. felis-infected mice revealed the presence of mucosal B220+ cells coalescing into lymphoid follicles surrounded by aggregates of Thy-1.2+ T cells; CD4+, CD5+, and alpha beta T cells predominated in organized gastric mucosal and submucosal lymphoid tissue, and CD11b+ cells occurred frequently in the mucosa. Follicular B cells comprised immunoglobulin M+ (IgM+) and IgA+ cells. Numerous IgA-producing B cells were present in the gastric glands, the lamina propria, and gastric epithelium. Infected animals developed anti-H. felis serum IgM antibody responses up to 8 weeks postinfection and significant levels of IgG anti-H. felis antibody in serum, which remained elevated throughout the 50-week course of the study.

Animals↗
PubMed1993

GSP1 and GSP2, genetic suppressors of the prp20-1 mutant in Saccharomyces cerevisiae: GTP-binding proteins involved in the maintenance of nuclear organization.

The temperature-sensitive mutation prp20-1 of Saccharomyces cerevisiae exhibits a pleiotropic phenotype associated with a general failure to maintain a proper organization of the nucleus. Its mammalian homolog, RCC1, is not only reported to be involved in the negative control of chromosome condensation but is also believed to assist in the coupling of DNA replication to the entry into mitosis. Recent studies on Xenopus RCC1 have strongly suggested a further role for this protein in the formation or maintenance of the DNA replication machinery. To elucidate the nature of the various components required for this PRP20 control pathway in S. cerevisiae, we undertook a search for multicopy suppressors of a prp20 thermosensitive mutant. Two genes, GSP1 and GSP2, were identified that encode almost identical polypeptides of 219 and 220 amino acids. Sequence analyses of these proteins show them to contain the ras consensus domains involved in GTP binding and metabolism. The levels of the GSP1 transcript are about 10-fold those of GSP2. As for S. cerevisiae RAS2, GSP2 expression exhibits carbon source dependency, while GSP1 expression does not. GSP1 is an essential gene, and GSP2 is not required for cell viability. We show that GSP1p is nuclear, that it can bind GTP in an in vitro assay, and finally, that a mutation in GSP1p which activates small ras-like proteins by increasing the stability of the GTP-bound form causes a dominant lethal phenotype. We believe that these two gene products may serve in regulating the activities of the multicomponent PRP20 complex.

Base Sequence↗
PubMed1993

IgH diversity in an individual with only one million B lymphocytes.

Immunoglobulin sequences from an individual Xenopus laevis froglet were analyzed for combinatorial and junctional diversity. In an animal with about 10(6) B lymphocytes, at least 26 out of the 56 VH1 genes available in a diploid genome were expressed, as were all JH segments. Junctional diversity was similar to that observed in Xenopus tadpole sequences, that is, little or no N diversification was found and the recombination site sometimes occurred in a region of V/D or D/J homology. The froglet IgH diversity is further restricted by the elimination of D-gene participation through direct V to J joining. Of the six complementary-determining regions (CDR) contributing to the structure of the antigen-combining site, CDR3 is the most variable in sequence and structure. Froglet IgH CDR3 are restricted to both aspects. Compared to IgH sequences isolated from a 5-month-old adult, froglet CDR3 were, on the average, two codons shorter; overall, 58% of the froglet Ig sequences isolated carried CDR3 of < or = 7 codons, compared to 30% of the adult sequences. In addition to being shorter, the tadpole/froglet CDR3 are less variable in sequence, as the absence of N regions also results in the V/D and D/J junctions being derived from germline elements. We therefore suggest that latent anti-adult specificities are not eliminated in situ, in the tadpole, but rather that such germline gene segments, singly or in their combinations thereof, that can potentially react to adult self-epitopes after metamorphosis have been counterselected during the course of evolution.

Animals↗
PubMed1993

[Noninvasive fetal pulse oximetry sub partu. Experiences with the Ohmeda Biox 3700 and the Baxter Asat 1000 Pulse Oximeter].

In this study oxygen saturation was measured at the presenting part of the fetus during labour. We used two different reflectance sensors together with two different pulse oximeters. The Baxter Asat 100 displayed a 25% lower functional oxygen saturation of haemoglobin (SaO2) compared to the Ohmeda Biox 3700 pulse oximeter. The mean duration of application using the Ohmeda Biox 3700 together with an adapted finger sensor was 36 min (SD +/- 17 min), an effective measurement was achieved for 15 min (SD +/- 9 min). The mean duration of application using the Baxter Asat 100 together with a commercial Baxter reflex sensor was 88 min (SD +/- 96 min), an effective measurement was attained for 73 min (SD +/- 77 min).

Adult↗
PubMed1993

Prp20, the Saccharomyces cerevisiae homolog of the regulator of chromosome condensation, RCC1, interacts with double-stranded DNA through a multi-component complex containing GTP-binding proteins.

Prp20, a homolog to the mammalian negative regulator of chromosome condensation, RCC1, is retained on double-stranded (ds) DNA-cellulose when extracts are prepared from asynchronously growing wild-type yeast strains. Conversely, neither Prp20 from ts mutant cell extracts nor wt yeast Prp20 produced in Escherichia coli, bind to dsDNA-cellulose. In vitro reconstitution assays using E. coli-expressed Prp20 and inactivated ts mutant extracts of prp20-1 reveal that the Prp20 protein requires the assistance of other proteins in the cell extract to promote its binding to dsDNA. Immunoprecipitations and sizing-column-chromatography indicate that the Prp20 protein binds to the dsDNA column through a multicomponent complex composed of six to seven proteins, which has a collective molecular mass greater than 150,000 Da. At least three of the members of this Prp20 complex will bind GTP in vitro. Moreover, the Prp20 complex is shown to specifically lose its ability to bind dsDNA during the DNA replication phase of the cell cycle. This loss of dsDNA binding during the S phase of the cell cycle does not affect the proper organization of the nucleoplasm and appears to be reversed before the cell enters mitosis.

Cell Cycle Proteins↗