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B Marshall

Publications and source records attributed to B Marshall.

At least 73 records · Page 4Linked to original sources
PubMed1994

PCR-based restriction fragment length polymorphism typing of Helicobacter pylori.

We applied a molecular typing approach for Helicobacter pylori that uses restriction fragment length polymorphism (RFLP) analyses of an 820-bp PCR-amplified portion of the ureC gene in H. pylori. The PCR products were digested with restriction enzyme HhaI, MboI, or MseI, and the fragments generated were analyzed by agarose electrophoresis. Among 25 independent clinical isolates, each showed a different pattern when a combination of the three RFLP patterns was used. Using this method, we studied isolates from the antrum or the body of the stomach of 14 patients before and after antibiotic therapy. Before treatment, successful isolation of H. pylori from the two sites of the stomach was possible for 12 of the 14 patients. For 10 of these 12 patients, each pair of isolates had identical RFLP profiles. For the other two patients (16.7%), however, isolates from the antrum and the body of the stomach had different RFLP profiles. Treatment was successful for 6 of the 14 patients; of the 8 patients with treatment failures, 5 had identical isolate pairs. In each case, the isolates found posttreatment were the same as the pretreatment isolates. For one of the patients who was colonized with two different isolates pretreatment, one of the isolates was identified at both sites after unsuccessful treatment. We also studied six long-term follow-up patients who had sequential biopsies at intervals of up to 5 months. Each follow-up isolate from each patient had the same RFLP profile as the initial isolate. This typing method provides a reliable and reproducible typing scheme for the study of H. pylori infections and indicates that infection with more than one H. pylori isolate is not rare.

Bacterial Typing Techniques↗
PubMed1993

Analysis of MHC genomic structure and gene content between HLA-B and TNF using yeast artificial chromosomes.

To characterize the genomic structure and gene content between HLA-B and TNF we studied three overlapping yeast artificial chromosome (YAC) clones derived from the Boleth cell line carrying the 62.1 MHC ancestral haplotype (AH). In particular, we have evaluated the stability of haplospecific sequence motifs (haplospecific geometric elements) in YACs. By PCR and gene scanning we show that the two larger YAC clones (318G11 and 8F2) exhibit features characteristic of the 62.1 AH carried by the parental cell line as well as those of a separate cell line (BSM) which also carries 62.1. It is concluded that a highly polymorphic duplicated region is represented faithfully in spite of the fact that it contains sequences that could be interpreted as simple repeats liable to mutations. In contrast, microsatellites AFM031 and AFM158, which are also located in the MHC, showed greater instability and the structure in the YACs was not consistent with genomic structure. Likewise, different examples of the same ancestral haplotype show differences at these microsatellite loci. We conclude that polymorphic repeat sequences may exhibit a range of stabilities in vivo and that this may be reflected in their stability in YACs. Northern blotting using the largest YAC clone revealed several novel transcripts which await localization.

Blotting, Northern↗
PubMed1993

New major histocompatibility complex genes.

The MHC is a region of some 4 megabases that has been studied intensively owing to the large number of diseases that are associated with susceptibility genes within this region of the genome. The total number of genes located within the MHC is now approximately 100, but more can be predicted. Recently identified genes within the MHC include PERB6, a large gene producing multiple transcripts located between HLA-B and TNF, and PERB1, a member of the protein tyrosine kinase-gene family. PERB6 was identified by YAC probing of tissue blots, while PERB1 was identified by genomic sequencing.

Chromosome Mapping↗
PubMed1993

Mercury released from dental "silver" fillings provokes an increase in mercury- and antibiotic-resistant bacteria in oral and intestinal floras of primates.

In a survey of 640 human subjects, a subgroup of 356 persons without recent exposure to antibiotics demonstrated that those with a high prevalence of Hg resistance in their intestinal floras were significantly more likely to also have resistance to two or more antibiotics. This observation led us to consider the possibility that mercury released from amalgam ("silver") dental restorations might be a selective agent for both mercury- and antibiotic-resistant bacteria in the oral and intestinal floras of primates. Resistances to mercury and to several antibiotics were examined in the oral and intestinal floras of six adult monkeys prior to the installation of amalgam fillings, during the time they were in place, and after replacement of the amalgam fillings with glass ionomer fillings (in four of the monkeys). The monkeys were fed an antibiotic-free diet, and fecal mercury concentrations were monitored. There was a statistically significant increase in the incidence of mercury-resistant bacteria during the 5 weeks following installation of the amalgam fillings and during the 5 weeks immediately following their replacement with glass ionomer fillings. These peaks in incidence of mercury-resistant bacteria correlated with peaks of Hg elimination (as high as 1 mM in the feces) immediately following amalgam placement and immediately after replacement of the amalgam fillings. Representative mercury-resistant isolates of three selected bacterial families (oral streptococci, members of the family Enterobacteriaceae, and enterococci) were also resistant to one or more antibiotics, including ampicillin, tetracycline, streptomycin, kanamycin, and chloramphenicol. While such mercury- and antibiotic-resistant isolates among the staphylococci, the enterococci, and members of the family Enterobacteriaceae have been described, this is the first report of mercury resistance in the oral streptococci. Many of the enterobacterial strains were able to transfer mercury and antibiotic resistances together to laboratory bacterial recipients, suggesting that the loci for these resistances are genetically linked. Our findings indicate that mercury released from amalgam fillings can cause an enrichment of mercury resistance plasmids in the normal bacterial floras of primates. Many of these plasmids also carry antibiotic resistance, implicating the exposure to mercury from dental amalgams in an increased incidence of multiple antibiotic resistance plasmids in the normal floras of nonmedicated subjects.

Animals↗
PubMed1993

Clarithromycin as monotherapy for eradication of Helicobacter pylori: a randomized, double-blind trial.

UNLABELLED: Current regimens to eradicate Helicobacter pylori usually consist of metronidazole plus a bismuth compound, as well as a third agent such as tetracycline. Such regimens are not ideal because organisms may be metronidazole-resistant, side-effects occur, and compliance is often poor. This randomized, double-blind study was designed to assess the ability of clarithromycin, a new macrolide antimicrobial, as monotherapy to eradicate H. pylori. Thirty-seven healthy volunteers who were H. pylori positive by 13C-urea breath test plus histology and/or culture completed 14 days of oral therapy with clarithromycin in one of three dosages. Eradication, defined as all three tests negative at 4-6 wk after the end of therapy, was achieved in 2/13 (15%) with clarithromycin 500 mg bid, 4/11 (36%) with 1000 mg bid, and 7/13 (54%) with 500 mg qid. Isolates of H. pylori were resistant to clarithromycin prior to therapy in 12% of subjects, and became resistant during therapy in 21% of subjects. Taste perversion, the most common side effect, resulted in one subject terminating therapy. CONCLUSIONS: Whereas clarithromycin is a promising antimicrobial in the eradication of H. pylori, it is not sufficient to be used as monotherapy.

Adult↗
PubMed1993

Stimulation regimens in Assisted Reproductive Technology (ART) programme: experience in the University Hospital, Singapore.

Ovarian stimulation is critical to the success of patients in Assisted Reproductive Technology (ART) programmes. We compared two stimulation regimes retrospectively for ART in the NUH programme. These were the 2:1 and the GnRHa-FSH/hMG regimes. The former was our first-line regime while the latter was used for cycles where there was a prior endogenous LH surge, previous poor response, or an elevated LH level between days three to five of the cycle. All cycles in our ART programme in 1991 were studied, except those for special research procedures, e.g. micro-insemination sperm transfer (MIST) cycles, a total of 241 cycles. Cancellation rates were 14.4% (21 of 146 cycles) and 37.3% (19 of 51 cycles) for the 2:1 and GnRHa-FSH/hMG regimes respectively (p > 0.001). For the 2:1 regime, the majority of cancellations were due to ovulation prior to the oocyte recovery (42.9%; nine of 21 cycles). However, for the GnRHa-FSH/hMG regime, almost all the cancellations were due to poor response (84.2%; 16 of 19 cycles). Fertilisation rates were lower for the 2:1 regime (for both IVF-ER and IVF-TET, where sperm quality was poorer) compared to the GnRHa-FSH/hMG (55.0 and 66.6% respectively; p < 0.001). Pregnancy rates were higher for the 2:1 regime when IVF-ER and IVF-TET were used (16.4% and 23.3% respectively per oocyte recovery, versus 9.8% and 18.8% respectively for the GnRHa-FSH/hMG regime).

Drug Evaluation↗
PubMed1993

Transhiatal esophagectomy for benign and malignant disease.

Transhiatal esophagectomy has been performed in 583 patients with diseases of the intrathoracic esophagus: 166 (28%) benign and 417 (72%) malignant (6% upper, 28% middle, and 66% lower third and cardia). The benign esophageal diseases included strictures (40%); neuromotor dysfunction-achalasia (24%), esophageal spasm (8%); recurrent gastroesophageal reflux (16%); acute perforation (5%); acute caustic injury (2%); and others (3%). Among the patients with benign disease, 60% had undergone at least one prior esophageal operation. Transhiatal esophagectomy was possible in 97% of patients in whom it was attempted, 19 patients (13 with benign disease and 6 with carcinoma) requiring addition of a thoracotomy for esophageal resection. Esophageal resection and reconstruction were performed in a single operation in all but 5 patients. The esophageal substitute was positioned in the posterior mediastinum in the original esophageal bed in 96%. Stomach was used to replace the esophagus in 553 patients (95%) and colon in 28 (5%) who had undergone prior gastric resections. Overall hospital mortality was 5% in patients with benign disease and 5% in those with carcinoma. There was 1 intraoperative death caused by uncontrollable hemorrhage. Complications included intraoperative entry into a pleural cavity necessitating a chest tube (74%), anastomotic leak (9%), recurrent laryngeal nerve paralysis (3%), and chylothorax and tracheal laceration (< 1% each). Three patients required reoperation for mediastinal bleeding. Average intraoperative blood loss was 875 ml (1023 ml for benign disease and 817 ml for carcinoma). Of the surviving patients, 88% were discharged able to swallow within 3 weeks of operation and 78% within 2 weeks. The actuarial survival of the patients with carcinoma is similar to that reported after more traditional transthoracic esophagectomy. Among patients with benign disease, good or excellent functional results have been achieved in nearly 70% after a cervical esophagogastric anastomosis. Although approximately 44% have required one or more anastomotic dilations within 1 to 3 months of operation, true anastomotic strictures have developed in 10%. Clinically troublesome nocturnal reflux has occurred in 3%. Transhiatal esophagectomy is feasible in most patients requiring esophageal resection for either benign or malignant disease and is a safe, well-tolerated operation if performed with care and for the proper indications.

Adenocarcinoma↗
PubMed1992

Views of problem drinking among Native American, Hispanic, and Anglo children.

Native American, Hispanic, and Anglo sixth graders reacting to an example of teenage problem drinking expressed similar beliefs and attitudes in many respects. However, Native American children viewed the problem as less serious, subscribed more to a disease theory of alcoholism, attributed less causal responsibility to the individual, and adopted a less aggressive approach toward treatment than did Hispanic, and especially Anglo, children. Their less conventional value orientations accounted for all these differences except their stronger endorsement of a disease theory of problem drinking.

Age Factors↗
PubMed1992

Improved pregnancy rate after transfer of embryos grown in human fallopian tubal cell coculture.

OBJECTIVE: To evaluate the embryonic behavior in vitro and the pregnancy and implantation rates of embryos grown in a human ampullary cell coculture system. DESIGN: In a prospective study, two pronuclei embryos were cultured on human ampullary feeder layers up to the two to six-cell and blastocyst stages and replaced either as tubal, uterine, or sequential transfers. SETTING: Assisted reproductive technology program in a university-based hospital. PATIENTS: Fifty women with a mean age of 35.6 years who went through a single coculture cycle. Thirty of the patients were admitted for in vitro fertilization (IVF) and 20 for tubal embryo transfer (TET). RESULTS: The overall clinical pregnancy rate (PR) for all 50 patients was 44% per cycle (IVF, 37%; TET, 55%) and the implantation rate was 31.8% (IVF, 31.0%; TET, 32.6%). Sixty-eight percent of pregnant patients were over 35 years, and 68% had two previously failed assisted reproduction cycles. Five of 9 patients who received sequential transfers became pregnant. Three of the 22 pregnancies aborted (2 after sequential transfer), and there was one ectopic. Overall, 88% of two to six-cell stage embryos were of good quality. CONCLUSIONS: The human ampullary coculture system produces better quality embryos, increased numbers of blastocysts with improved PRs and implantation rates. The beneficial effects of the feeder layer may be through the release of embryotrophic factors and detoxification of the medium by the cells. Coculture is a new concept in assisted reproduction and has tremendous potential in boosting conception rates by mimicking the in vivo environment.

Adult↗
PubMed1992

Outcome of 143 pregnancies conceived by assisted reproductive techniques.

One hundred and forty-three pregnancies conceived by assisted reproductive techniques (ART) from October 1985 to June 1989 in the National University Hospital, Singapore, resulted in 66 deliveries and 89 babies. There were 27 (18.7%) biochemical pregnancies, 44 (30.7%) clinical miscarriages and 6 (4.2%) ectopic pregnancies when total pregnancies were considered. Of those who continued pregnancy to second trimester multiple births occurred in 20 (13.3%) patients. A high incidence of vaginal bleeding and hypertension in pregnancy was noted in 32 (48.5%) patients and 18 (27.3%) patients, respectively. Caesarean section was the method of delivery in 48.5% of patients. Twenty-six (29.2%) babies required admission to the neonatal intensive care unit. All babies except one set of twins delivered at 24 weeks of amenorrhoea survived. Fetal abnormality was noted in 2 cases.

Adult↗
PubMed1991

1991 cervical screening recommendations: a working group report.

The Department of Health and the Cancer Society invited a working group to review the 1985 recommendations on cervical screening. Minor modifications have been made to the earlier recommendations in the light of more information about the effectiveness of different screening policies, and in the expectation that comprehensive cytology registers to ensure recall and follow up of abnormalities will be in place shortly. All women from the age of 20 up to 70 years should be offered cervical screening every three years. Any woman who has never had sexual intercourse or who has had a hysterectomy with complete removal of the cervical epithelium for a benign condition need not be screened. Women should have a second smear within one year if they have never had a smear before or if more than five years have passed since their last smear. But recall through the register should not be more frequently than three yearly for women with a history of normal smears.

Adult↗
PubMed1991

Laser lithotripsy: a nursing perspective.

Laser lithotripsy represents the urologist's newest option in urinary stone management and is fast becoming the procedure of choice when treating calculi. Approximately 400,000 people yearly require treatment for urinary stone disease. 60% pass the calculi spontaneously while 40% require some type of intervention (Dretler, 1988). While the initial cost of the laser is expensive, maintenance cost is relativity low. Therefore, the laser lithotripter becomes a very cost effective tool when compared with other alternatives because of the decreased hospital stay and the absence of significant complications. Adverse effects to the patient are primarily due to the endoscopic procedure and not the laser itself. Additional benefits to the patient include reduced pain and edema, minimal bleeding, no incision and decreased convalescence time.

Humans↗
PubMed1990

Inter- and intraspecies spread of Escherichia coli in a farm environment in the absence of antibiotic usage.

The spread of wild-type Escherichia coli bearing a transferable plasmid was studied in a farm environment. E. coli of bovine and porcine origin were marked by resistance to nalidixic acid (Nar) or rifampicin (Rfr), and a transferable, multiple resistance plasmid (pSL222-1 derivative of plasmid R222) was introduced by conjugation. In separate experiments, the two mutant derivatives were fed back to the respective host animals, which were housed adjacent to, but separate from, one or more "recipient" animals. No antibiotic was given. Although the Rfr derivatives declined rapidly to undetectable levels within 1 week, the Nar mutants of bovine and porcine origin persisted in the original hosts and in their bedding throughout most of each 4-month test period. Test bacteria were isolated from mice residing in the same pen as the donor animals and from multiple secondary hosts having direct or indirect contact with the inoculated donors, but not from neighboring animals maintained in isolation. The bovine mutant was excreted by two caretakers for greater than 4 weeks and was recovered for 4-6 weeks from pigs, fowl, and flies. Although the porcine mutant appeared to colonize less effectively, it spread rapidly to flies and mice and was recovered transiently from humans and fowl. Despite high transfer rates of plasmid pSL222-1 from E. coli K-12 in vitro, transfer of the plasmid from the animal E. coli host was very low and transfer in vivo was not detected among indigenous gut or environmental bacteria. E. coli of animal origin can spread rapidly and can colonize the intestinal tract of humans and of other animals in the absence of antibiotic selection.

Animals↗
PubMed1990

Recent trends in incidence, morbidity and survival in Down's syndrome.

The numbers of young adults with Down's syndrome is currently increasing due to improvements in survival and a period of increased incident numbers in the 1960s. Deaths from infection have shown the largest decline. Forty-one per cent of survivors suffer from one or more serious morbid conditions, principally congenital heart disease. These changes are adding to the pressures upon local authorities for day and residential care facilities.

Cause of Death↗
PubMed1990

Large haplotype-specific differences in inter-genic distances in human MHC shown by pulsed field electrophoresis mapping of healthy and type 1 diabetic subjects.

Type 1 diabetes is associated with extended haplotypes defined by combinations of specific alleles of genes in the MHC. We have used pulsed field gel electrophoresis mapping to examine the gross structure of the Class II region of the MHC and its relationship to susceptibility to Type 1 diabetes. We have studied heterozygous members of a family in which susceptibility to Type 1 diabetes is associated with an A1/B8/DR3 haplotype and resistance with A2/B7/DR2, an unrelated diabetic DR3,4 patient and a healthy DR4,w10 subject and a DR2/Dw2 cell line. Digestion was performed with the enzymes Sst II, Mlu I, and Pvu I and hybridization with 21-hydroxylase, DRA, DQB, DOB and DPA probes. Within the DQ/DR region the DR4- and DR7-bearing haplotypes studied contain insertions of 140-150kb relative to the DR3 haplotypes whilst the DR2 haplotype in the family was smaller than the DR3 haplotypes by 130kb, whilst that in the cell line was smaller by up to 220kb. This cell line, previously thought to be homozygous by consanguinity, was also shown to be heterozygous in the DP region. Although no differences between diabetic and healthy subjects were observed within the family, these differences in long-range structure may be of importance to the etiology of Type 1 diabetes, as well as to the evolution of the MHC.

Chromosome Mapping↗
PubMed1990

Development of an Adhesion Assay and Characterization of an Adhesion-Deficient Mutant of Pseudomonas fluorescens.

A sand column adhesion assay was developed which distinguishes the adhesion abilities of a number of pseudomonads isolated from fine sandy loam. Pseudomonas fluorescens Pf0-1 which adhered at >90% of the total cells added was subjected to transposon Tn5 insertion mutagenesis. From 2,500 Pf0-1::Tn5 mutants examined in the sand column assay, two adhesion-deficient Pf0-1 mutants showing <50% attachment were isolated. Marker exchange analysis of one of these mutants, Pf0-5, confirmed that the decreased adhesion was linked to the Tn5 insertion in the chromosome. The growth rate of Pf0-5 in enriched media and sterile soil was similar to that of the wild type; in minimal medium, however, Pf0-5 grew faster. In a soil column assay, less Pf0-5 than wild-type bacteria were recovered, suggesting a decreased ability to persist in soil. A 34-kilodalton major outer membrane protein present in the wild type was missing in Pf0-5. Transmission electron microscopy of the cell surface revealed that the wild-type possessed polar flagella which were absent in the mutant.

Journal Article↗