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Biomedical subjects

M Simmonds

Publications and source records attributed to M Simmonds.

At least 19 recordsLinked to original sources
PubMed2001

Complete genome sequence of a multiple drug resistant Salmonella enterica serovar Typhi CT18.

Salmonella enterica serovar Typhi (S. typhi) is the aetiological agent of typhoid fever, a serious invasive bacterial disease of humans with an annual global burden of approximately 16 million cases, leading to 600,000 fatalities. Many S. enterica serovars actively invade the mucosal surface of the intestine but are normally contained in healthy individuals by the local immune defence mechanisms. However, S. typhi has evolved the ability to spread to the deeper tissues of humans, including liver, spleen and bone marrow. Here we have sequenced the 4,809,037-base pair (bp) genome of a S. typhi (CT18) that is resistant to multiple drugs, revealing the presence of hundreds of insertions and deletions compared with the Escherichia coli genome, ranging in size from single genes to large islands. Notably, the genome sequence identifies over two hundred pseudogenes, several corresponding to genes that are known to contribute to virulence in Salmonella typhimurium. This genetic degradation may contribute to the human-restricted host range for S. typhi. CT18 harbours a 218,150-bp multiple-drug-resistance incH1 plasmid (pHCM1), and a 106,516-bp cryptic plasmid (pHCM2), which shows recent common ancestry with a virulence plasmid of Yersinia pestis.

Chromosome Mapping↗
PubMed2001

Genome sequence of Yersinia pestis, the causative agent of plague.

The Gram-negative bacterium Yersinia pestis is the causative agent of the systemic invasive infectious disease classically referred to as plague, and has been responsible for three human pandemics: the Justinian plague (sixth to eighth centuries), the Black Death (fourteenth to nineteenth centuries) and modern plague (nineteenth century to the present day). The recent identification of strains resistant to multiple drugs and the potential use of Y. pestis as an agent of biological warfare mean that plague still poses a threat to human health. Here we report the complete genome sequence of Y. pestis strain CO92, consisting of a 4.65-megabase (Mb) chromosome and three plasmids of 96.2 kilobases (kb), 70.3 kb and 9.6 kb. The genome is unusually rich in insertion sequences and displays anomalies in GC base-composition bias, indicating frequent intragenomic recombination. Many genes seem to have been acquired from other bacteria and viruses (including adhesins, secretion systems and insecticidal toxins). The genome contains around 150 pseudogenes, many of which are remnants of a redundant enteropathogenic lifestyle. The evidence of ongoing genome fluidity, expansion and decay suggests Y. pestis is a pathogen that has undergone large-scale genetic flux and provides a unique insight into the ways in which new and highly virulent pathogens evolve.

Animals↗
PubMed2001

VN training scheme.

Explore the source record for details and available documents.

Animal Technicians↗
PubMed2001

Massive gene decay in the leprosy bacillus.

Leprosy, a chronic human neurological disease, results from infection with the obligate intracellular pathogen Mycobacterium leprae, a close relative of the tubercle bacillus. Mycobacterium leprae has the longest doubling time of all known bacteria and has thwarted every effort at culture in the laboratory. Comparing the 3.27-megabase (Mb) genome sequence of an armadillo-derived Indian isolate of the leprosy bacillus with that of Mycobacterium tuberculosis (4.41 Mb) provides clear explanations for these properties and reveals an extreme case of reductive evolution. Less than half of the genome contains functional genes but pseudogenes, with intact counterparts in M. tuberculosis, abound. Genome downsizing and the current mosaic arrangement appear to have resulted from extensive recombination events between dispersed repetitive sequences. Gene deletion and decay have eliminated many important metabolic activities including siderophore production, part of the oxidative and most of the microaerophilic and anaerobic respiratory chains, and numerous catabolic systems and their regulatory circuits.

Animals↗
PubMed2001

Long-term safety of oral transmucosal fentanyl citrate for breakthrough cancer pain.

This open-label study evaluated the long-term safety and tolerability of oral transmucosal fentanyl citrate (OTFC) in ambulatory cancer patients with breakthrough pain undergoing cancer care at 32 university- or community-based practices. Patients had participated in a previous short-term titration trial of OTFC, were experiencing at least one episode per day of breakthrough pain, and had achieved relief of their breakthrough pain with an opioid. Patients received OTFC units at a starting dosage strength determined in the short-term trial (200-1600 microg). Outcome measures included number of successfully treated breakthrough pains, global satisfaction rating (0 = poor through 4 = excellent), and side effects. In total, 41,766 units of OTFC were used to treat 38,595 episodes of breakthrough pain in 155 patients. Number of treatment days ranged from 1 to 423 (mean, 91 days). Patients averaged 2.9 breakthrough pain episodes per day. About 92% of episodes were successfully treated with OTFC and there was no trend toward decreased effectiveness over time. Most patients (61%) did not require dose escalation during treatment. Global satisfaction ratings were consistently above 3, indicating very good to excellent relief. Common adverse events associated with OTFC were somnolence (9%), constipation (8%), nausea (8%), dizziness (8%), and vomiting (5%). Six patients (4%) discontinued therapy due to an OTFC-related adverse event. There were no reports of abuse and no concerns about the safety of the drug raised by patients or families. OTFC was used safely and effectively during long-term treatment of breakthrough pain in cancer patients at home.

Administration, Oral↗
PubMed2001

EGF-responsive neural stem cells are a transient population in the developing mouse spinal cord.

The adult mouse forebrain, which exhibits substantial ongoing cell genesis, contains self-renewing multipotent neural stem cells that respond to epidermal growth factor (EGF), but the adult spinal cord, which exhibits limited cell genesis, does not. Spinal cord development is a process characterized by defined periods of cell histogenesis. Thus, in the present study we asked whether EGF-responsive neural stem cells are present within the spinal cord during development. At embryonic day (E) 11, subsequent to the onset of neurogenesis, only fibroblast growth factor (FGF) receptors and FGF-2 (requiring heparan sulphate)-responsive stem cells are present in the spinal cord. Between E12 and 14, at the peak of spinal cord neurogenesis and the onset of gliogenesis, EGF receptors appear along with clonally derived highly expandable EGF-responsive neural stem cells. Following the cessation of cell histogenesis, the adult spinal cord is largely devoid of both EGF receptors and EGF-responsive stem cells. On the other hand, the FGF receptor1c subtype and multipotent FGF-2-responsive neural stem cells are present in early development and in the adult. The order of appearance of spinal cord neural stem cells and in vitro lineage analysis suggests that a more primitive FGF-2-responsive stem cell produces the EGF-responsive stem cell. These findings suggest that EGF-responsive neural stem cells appear transiently in the spinal cord, during the peak period of cell histogenesis, but are no longer present in the relatively quiescent adult structure.

Animals↗
PubMed2001

Salmonella enterica serovar Typhi possesses a unique repertoire of fimbrial gene sequences.

Salmonella enterica serotype Typhi differs from nontyphoidal Salmonella serotypes by its strict host adaptation to humans and higher primates. Since fimbriae have been implicated in host adaptation, we investigated whether the serotype Typhi genome contains fimbrial operons which are unique to this pathogen or restricted to typhoidal Salmonella serotypes. This study established for the first time the total number of fimbrial operons present in an individual Salmonella serotype. The serotype Typhi CT18 genome, which has been sequenced by the Typhi Sequencing Group at the Sanger Centre, contained a type IV fimbrial operon, an orthologue of the agf operon, and 12 putative fimbrial operons of the chaperone-usher assembly class. In addition to sef, fim, saf, and tcf, which had been described previously in serotype Typhi, we identified eight new putative chaperone-usher-dependent fimbrial operons, which were termed bcf, sta, stb, ste, std, stc, stg, and sth. Hybridization analysis performed with 16 strains of Salmonella reference collection C and 22 strains of Salmonella reference collection B showed that all eight putative fimbrial operons of serotype Typhi were also present in a number of nontyphoidal Salmonella serotypes. Thus, a simple correlation between host range and the presence of a single fimbrial operon seems at present unlikely. However, the serotype Typhi genome differed from that of all other Salmonella serotypes investigated in that it contained a unique combination of putative fimbrial operons.

Base Sequence↗
PubMed2001

Effective selective head cooling during posthypoxic hypothermia in newborn piglets.

Selective head cooling has been proposed as a neuroprotective intervention after hypoxia-ischemia in which the brain is cooled without subjecting the rest of the body to significant hypothermia, thus minimizing adverse systemic effects. There are little data showing it is possible to cool the brain more than the body. We have therefore applied selective head cooling to our hypoxia-ischemia piglet model to establish whether it is possible. Nine piglets were anesthetized, and brain temperature was measured at the surface and in the superficial (0.2 cm) and deep (1.7-2.0 cm) gray matter. Rectal (6-cm depth), skin, and scalp temperatures (T) were recorded continuously. Lowering T-rectal from normothermia (39 degrees C) to hypothermia (33.5-33.8 degrees C) using a head cap perfused with cold (6-24 degrees C) water was undertaken for up to 6 h. To assess the impact of the 45-min hypoxia-ischemia insult on the effectiveness of selective head cooling, four piglets were cooled both before and after the insult, and four, only afterward. During selective head cooling, it was possible to achieve a lower T-deep brain than T-rectal in all animals both before and after hypoxia. However, this was only possible when overhead body heating was used. The T-rectal to T-deep brain gradient was significantly smaller after the insult (median, 5.3 degrees C; range, 4.2-8.5 degrees C versus 3.0 degrees C; 1.7-7.4 degrees C; p = 0.008). During rewarming to normothermia, the gradient was maintained at 4.5 degrees C. We report for the first time a study, which by direct measurement of deep intracerebral temperatures, validates the cooling cap as an effective method of selective brain cooling in a newborn animal hypoxia-ischemia model.

Animals↗
PubMed2000

Complete DNA sequence of a serogroup A strain of Neisseria meningitidis Z2491.

Neisseria meningitidis causes bacterial meningitis and is therefore responsible for considerable morbidity and mortality in both the developed and the developing world. Meningococci are opportunistic pathogens that colonize the nasopharynges and oropharynges of asymptomatic carriers. For reasons that are still mostly unknown, they occasionally gain access to the blood, and subsequently to the cerebrospinal fluid, to cause septicaemia and meningitis. N. meningitidis strains are divided into a number of serogroups on the basis of the immunochemistry of their capsular polysaccharides; serogroup A strains are responsible for major epidemics and pandemics of meningococcal disease, and therefore most of the morbidity and mortality associated with this disease. Here we have determined the complete genome sequence of a serogroup A strain of Neisseria meningitidis, Z2491. The sequence is 2,184,406 base pairs in length, with an overall G+C content of 51.8%, and contains 2,121 predicted coding sequences. The most notable feature of the genome is the presence of many hundreds of repetitive elements, ranging from short repeats, positioned either singly or in large multiple arrays, to insertion sequences and gene duplications of one kilobase or more. Many of these repeats appear to be involved in genome fluidity and antigenic variation in this important human pathogen.

Antigenic Variation↗
PubMed2000

Complications from regional anaesthesia for carotid endarterectomy.

The complications of carotid endarterectomy (CEA) under cervical plexus blockade have yet to be fully evaluated. Two different cases are presented; both patients suffered sudden collapse following superficial and deep cervical plexus block in preparation for CEA. The causes, presenting signs and differential diagnoses are discussed. The safest cervical plexus anaesthetic block technique has not yet been established.

Aged↗
PubMed2000

Anaesthetists' records of pre-operative assessment.

The pre-operative anaesthetic records of 195 patients were analysed for the presence of 12 agreed core items of pre-operative assessment. This study showed that anaesthetists recorded 26.8 per cent of this information. In up to one-third of patients the following were recorded: smoking history, family history, gastro-oesophageal reflux, airway assessment, dental assessment, chest examination, heart-sounds and blood pressure. Previous anaesthesia, drug history and allergies were recorded in one to two-thirds of patients. Past medical history was recorded in over two-thirds of patients. With a view to improving the level of record-keeping, a formatted, pre-printed pre-operative assessment record was introduced into practice and two months later the audit was repeated. A small but non-significant improvement in record keeping was observed. An argument is made for the introduction of an interdisciplinary, unified anaesthetic pre-operative record.

Adolescent↗
PubMed1998

Phase II trial of topotecan as a 21-day continuous infusion in patients with advanced or metastatic adenocarcinoma of the pancreas.

The aim of this study was to determine the efficacy and toxicity of topotecan administered as a 21-day continuous intravenous infusion in patients with advanced or metastatic adenocarcinoma of the pancreas. 26 previously untreated patients with advanced or metastatic pancreatic adenocarcinoma received topotecan at a dose of 0.5 mg/m2/day or 0.6 mg/m2/day as a continuous intravenous infusion for 21 days. Courses were repeated every 28 days. 26 patients were assessable for response and toxicity on an intent-to-treat basis. The initial 8 patients at a starting dose of 0.6 mg/m2/day experienced unacceptable myelosuppression and dose delays. The subsequent 18 patients, therefore began therapy at a dose of 0.5 mg/m2/day. The major toxicity of topotecan at this dose and schedule was myelosuppression, which was reversible and non-cumulative. There were no complete responses and two partial responses for a total response rate of 8% (95% confidence interval, 1-25%). Response durations were 17 and 45 weeks. Stable disease was seen in 3 patients. The median time to progression for all patients was 8 weeks and the median survival was 20 weeks. Topotecan given as a 21-day continuous intravenous infusion has a similar response rate and median survival to our previously reported study of the 5-day short infusion regimen in pancreatic carcinoma.

Adenocarcinoma↗
PubMed1998

Therapists' conceptualization and characterization of the clinical concept of spinal stiffness.

BACKGROUND AND PURPOSE: The clinical concept of spinal stiffness provides one basis for applying spinal manipulation. Because the terms used to describe the perceptual results of manual spinal stiffness testing are poorly defined, the nature and number of attributes contained in the concept remain unclear. This study attempted to clarify the concept of spinal stiffness by examining the relationships among 31 published spinal stiffness descriptors using cluster analysis. SUBJECTS AND METHODS: Each stiffness descriptor was printed on a magnetized rubber strip. Physical therapists in Houston (Tex) and Sydney (New South Wales, Australia) judged the similarity of the stiffness descriptors by arranging them on a board. The squared Euclidean distance between words was calculated, and cluster analysis was performed using Ward's method. RESULTS: Cluster analysis reduced the 31 stiffness descriptors to three superclusters (limited mobility, increased mobility, and viscoelasticity) in both the Houston and Sydney data. CONCLUSION AND DISCUSSION: In a step toward improving the reliability of spinal stiffness judgments, this study has identified the fundamental characteristics of the clinical concept of spinal stiffness. Research is now needed to clearly define these characteristics and then develop protocols that will allow physical therapists to reliably rate these attributes.

Cluster Analysis↗
PubMed1998

Effect on attendance at breast cancer screening of adding a self administered questionnaire to the usual invitation to breast screening in southern England.

STUDY OBJECTIVE: The primary aim of the research described in this paper was to ascertain whether inclusion of a self administered questionnaire with the usual invitation to routine breast screening affected screening uptake. Secondary aims included establishing appropriate questionnaire distribution and collection methods within the framework of the National Health Service Breast Screening Programme and optimisation of questionnaire design. DESIGN: Randomised study. SETTING: Oxfordshire and West of London Breast Screening Units. PARTICIPANTS/METHODS: 6400 women invited for routine screening mammography were individually randomised to receive either the usual breast screening invitation alone, or to receive the usual invitation accompanied by a self administered questionnaire, to be returned at the time of screening. Participants were then followed up and attendance rates at screening were compared between groups. MAIN RESULTS: Screening attendance rates were similar in women who did and did not receive a questionnaire (71% in each group). Of those who were sent a questionnaire and attended for screening, 77% returned a completed questionnaire. Screening uptake was not affected by the way in which the questionnaire was returned or by whether or not personal details and signed permission for follow up were requested. CONCLUSIONS: The inclusion of a self administered questionnaire accompanying the invitation to breast screening did not adversely affect screening uptake. A high proportion of women completed the questionnaire.

Breast Neoplasms↗
PubMed1998

Dose-titration, multicenter study of oral transmucosal fentanyl citrate for the treatment of breakthrough pain in cancer patients using transdermal fentanyl for persistent pain.

PURPOSE: Supplemental, "as-needed," administration of an opioid is a common approach to the problem of breakthrough pain in cancer patients. Oral transmucosal fentanyl citrate (OTFC) is undergoing investigation as a new treatment for breakthrough pain. The primary purpose of the study was to demonstrate that a single-unit dose of OTFC can safely and effectively treat breakthrough pain. A secondary goal was to determine appropriate dosing guidelines. PATIENTS AND METHODS: This was a multicenter, randomized, double-blind, dose-titration study in 62 adult cancer patients using transdermal fentanyl for persistent pain. Consenting patients provided 2 days of baseline data to evaluate the performance of their usual breakthrough pain medication. Patients then randomly received 200 microg or 400 microg OTFC in double-blind fashion. (Patients were always assigned, rather than randomized, to 200 microg if 400 microg represented > 20% of around-the-clock medication.) Pain intensity (PI), pain relief (PR), and global satisfaction scores were recorded. OTFC was then titrated until the patient received adequate PR for each episode using one OTFC unit. Orders to titrate up were ignored one third of the time to improve the blind. Two days of baseline data were compared with 2 days of OTFC data after titration identified an effective dose of OTFC. RESULTS: Most patients (76%) found a safe and effective dose of OTFC. There was no meaningful relationship between the around-the-clock opioid regimen and the effective dose of OTFC. In open-label comparisons, OTFC produced a faster onset of relief and a greater degree of PR than patients' usual breakthrough medication. Somnolence, nausea, and dizziness were the most common side effects associated with OTFC. CONCLUSION: Most patients find a single OTFC dosage that adequately treats breakthrough pain. The optimal dose is found by titration and is not predicted by around-the-clock dose of opioids.

Administration, Buccal↗