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David Walker

Publications and source records attributed to David Walker.

36 records · Page 2Linked to original sources
PubMed2003

Spasticity, strength, and gait changes after surgery for cervical spondylotic myelopathy: a case report.

STUDY DESIGN: A case report with repeated measures is presented. OBJECTIVE: To describe an objective method for evaluating changes in upper- and lower-extremity spasticity and strength, as well as temporal and kinematic gait variables, after surgical intervention for cervical spondylotic myelopathy. SUMMARY OF BACKGROUND DATA: Degenerative cervical spinal disease is a common disorder, with some form of spondylosis demonstrated radiographically in more than 80% of those older than 55 years. Normative pre- and postoperative objective data quantifying spasticity, strength, and gait do not exist. METHODS: A 65-year-old woman underwent C2-C3 anterior cervical discectomy and fusion for progressive myelopathy secondary to a spondylosis and disc herniation. The measure for spasticity and strength at the ankles and elbows and a gait analysis were collected before surgery and at 11 days, 3 and 6 months after surgery. Spasticity and strength were assessed using a dynamometer, and a six-camera video system was used to record the gait. RESULTS: Preoperative left elbow flexor spasticity was more than 10 times greater than the values for the able bodies. It was reduced to normal levels after surgery. Substantial presurgery weakness was present in the elbow flexors and extensors bilaterally. Elbow extensor strength was at able-body levels after surgery. Gait speed was 57% of the able-body level before surgery and 78% of the able-body level 6 months after surgery. CONCLUSIONS: This case study demonstrated the role of biomechanics in characterizing impairments associated with cervical spondylosis and its surgical intervention. Measures for spasticity, strength, and gait taken before and after surgery indicated a favorable outcome. This report provides a foundation for the continued use of biomechanical methods to measure changes in function and impairments associated with surgical intervention of cervical spine disorders.

Aged↗
PubMed2003

The influenza virus gene pool in a poultry market in South central china.

We surveyed influenza activity in a live poultry market in Central China for 16 months, isolating viruses from 1% of 6360 fecal samples. We obtained multiple H3N6, H9N2, H2N9, H3N3, and H4N6 isolates and single H1N1 and H3N2 isolates. Two distinct H3 molecules were identified; other hemagglutinin subtypes were phylogenetically homogeneous. The H3N6 viruses (9 genotypes) and H9N2 viruses (4 genotypes) were genetically heterogeneous, whereas the H2N9, H3N3 and H4N6 viruses had single genotypes. Thirteen representative viruses were tested for their ability to replicate in quail and chickens. All tested viruses replicated in the respiratory tract of quail. Only nine of the viruses were shed in detectable levels in infected chickens, and four of these were detected in less than 50% of infected birds. A single H4N6 isolate caused disease and systemic spread in chickens. These findings show that quail are broadly susceptible to different subtypes of influenza A virus.

Animals↗
PubMed2003

Increased mRNA expression of kynurenine pathway enzymes in human placentae exposed to bacterial endotoxin.

Intra-amniotic bacterial infection is a major risk factor for cerebral impairment in infants that are born pre-term however, the causal pathways are largely unknown. Whether placental derived, neuroactive kynurenine metabolites play any role in fetal cerebral damage during episodes of intra-amniotic infection is presently unknown. In this preliminary study, we explored if kynurenine metabolites may be involved, examining if mRNAs of enzymes involved in tryptophan catabolism through the kynurenine pathway (KP) were expressed in the placenta and if their expression was co-ordinately altered with exposure to bacterial infection. We found that placentae from healthy women at term and those with clinical signs of amniotic fluid bacterial infection pre-term expressed mRNAs of the KP enzymes, with higher expression overall in the infected group. Significant increases in indoleamine 2,3-dioxygenase (IDO), tryptophan dioxygenase (TDO) and kynureninase (KYNase) expression were detected in association with infection. These findings suggest that tryptophan may be constitutively degraded through the KP in the human placenta. Whether higher concentrations of placental derived kynurenine metabolites enter the fetus during episodes of infection and their physiological roles if any remains to be elucidated.

Female↗
PubMed2003

The attitudes and beliefs of clinicians involved in teaching undergraduate musculoskeletal clinical examination skills.

The aim of this study was to explore which regional musculoskeletal examination skills medical students should learn and be examined on. A qualitative research study was undertaken, and six focus groups were formed involving 36 consultants from four chosen specialties. The feeling was that greater emphasis should be placed on the functional assessment of a patient. Students should be able to discern through examination what the patient can and cannot do with his/her affected limb/joint. It was felt that many of the traditional eponymously named special tests (e.g.Thomas' test, Trendelenburg's test) should be dispensed with along with traditional descriptions such as varus, valgus, swan neck and Boutonniere deformities. It was felt these were often a cause of confusion for medical undergraduates. A broad view and diversity in opinions was detected with differences between specialties. The strongest theme to emerge by far was the desire to simplify and standardize the regional examination as much as possible.

Attitude of Health Personnel↗
PubMed2003

Regional musculoskeletal examination: what the students say.

Confusion exists over which musculoskeletal examination skills medical students should learn. This study aimed to explore the views of third-year medical students. This was a qualitative study to allow in-depth exploration of beliefs and attitudes. Twenty students were randomly assigned to 1 of 2 focus groups. Their attitudes towards musculoskeletal examination were explored and discussed. The groups' discussions were recorded, transcribed, and framework analysis was undertaken with the aid of NUD*IST computer software. The following themes were identified: students dislike eponymous names for clinical tests; students felt there is a need for a more structured approach to musculoskeletal examination; students appeared unaware that many clinical tests were not based on evidence; students complained of a lack of confidence in the use of musculoskeletal clinical tests. Student's confidence in their musculoskeletal examination skills may be improved by the development of an agreed set of so-called core examination skills.

Journal Article↗
PubMed2003

Recent advances in optic nerve glioma with a focus on the young patient.

PURPOSE OF REVIEW: Optic tract low-grade gliomas are one of the commonest category of neoplasm presenting in childhood and early adolescence. Recent reports covering their aetiology, imaging techniques, the application of novel radiotherapy techniques and chemotherapy are reported. RECENT FINDINGS: These tumours are increasingly being seen as markers of enhanced risk in patients and their families for the subsequent development of central nervous system tumours. Modern imaging techniques are being explored for their diagnostic sensitivity and specificity as well as their ability to describe, with greater precision, anatomical boundaries in order to minimize, through conformal techniques, radiation doses to organs at risk within the brain. Increasing numbers of trials of chemotherapy agents are demonstrating efficacy in this tumour category. SUMMARY: Visual pathway low-grade astrocytomas of childhood are the subject of diverse research into diagnostic aetiological and treatment aspects aimed at tailoring diagnostic and treatment procedures more precisely to the needs of the young patient for this tumour type.

Child↗
PubMed2003

Ultrastructural and genetic evidence of a reptilian tick, Aponomma hydrosauri, as a host of Rickettsia honei in Australia: possible transovarial transmission.

In 1993, a novel rickettsia was isolated from the blood of inhabitants of Flinders Island, Australia, with acute febrile illnesses. This rickettsia was found to be a new species of spotted fever group (SFG) rickettsia, eventually named Rickettsia honei. The suspected ectoparasite vector of this rickettsia has yet to be identified. The purpose of this study was to evaluate the presence of this rickettsial species in a suspected tick vector, Aponomma hydrosauri, by DNA sequencing and electron microscopy (EM). Ticks collected from an Australian blue-tongued lizard on Flinders Island and a copperhead snake in Tasmania were demonstrated to be infected with R. honei by PCR, DNA sequencing, and EM. Rickettsiae were found in ultrathin sections of salivary glands, malpighian tubules, and midgut epithelial cells. In a previous study with a R. honei-infected tick from Flinders Island, rickettsiae were found in the nuclei of midgut epithelial cells, and EM also revealed the presence of rickettsiae in the cytosol of oocytes and immature eggs, suggesting transovarial transmission. These results implicate A. hydrosauri as a possible host of R. honei on Flinders Island and Tasmania and also provide evidence favoring transovarial maintenance of R. honei.

Animals↗
PubMed2003

Deep infection by Trichophyton rubrum in an immunocompromised patient.

Dermatophytes are common pathogens of skin but rarely cause invasive disease. We present a case of deep infection by Trichophyton rubrum in an immunocompromised patient. T. rubrum was identified by morphological characteristics and confirmed by PCR. Invasiveness was apparent by histopathology and immunohistochemistry. The patient was treated successfully with itraconazole.

Antibodies, Fungal↗
PubMed2003

The use of video information in obtaining consent for female sterilisation: a randomised study.

HYPOTHESIS: Providing additional information by video in addition to the standard consultation in women requesting sterilisation increases patients' knowledge about the procedure with no change in anxiety levels. DESIGN: Randomised control trial in 6 weeks. POPULATION: Women requesting sterilisation (n = 31). SETTING: Gynaecology clinics in two teaching hospitals. METHODS: Comparison of providing additional information by video in addition to the standard consultation with the standard consultation. MAIN OUTCOME MEASURES: Patients' knowledge of sterilisation, anxiety levels and acceptance of the video approach. RESULTS: Women receiving video information as well as the standard consultation had significantly higher knowledge scores compared with women only receiving the conventional consultation. Women undergoing a conventional consultation (no video) in a nurse-led dedicated sterilisation clinic had significantly higher knowledge scores than women having their consultation in a general gynaecological clinic. There were no differences in anxiety levels between the groups. Information giving by video was acceptable to the majority of women. CONCLUSION: Videos are a reliable and consistent method of delivering information to women requesting female sterilisation.

Adult↗
PubMed2002

Cladistic analysis of anuran POMC sequences.

Procedures for performing cladistic analyses can provide powerful tools for understanding the evolution of neuropeptide and polypeptide hormone coding genes. These analyses can be done on either amino acid data sets or nucleotide data sets and can utilize several different algorithms that are dependent on distinct sets of operating assumptions and constraints. In some cases, the results of these analyses can be used to gauge phylogenetic relationships between taxa. Selecting the proper cladistic analysis strategy is dependent on the taxonomic level of analysis and the rate of evolution within the orthologous genes being evaluated. For example, previous studies have shown that the amino acid sequence of proopiomelanocortin (POMC), the common precursor for the melanocortins and beta-endorphin, can be used to resolve phylogenetic relationships at the class and order level. This study tested the hypothesis that POMC sequences could be used to resolve phylogenetic relationships at the family taxonomic level. Cladistic analyses were performed on amphibian POMC sequences characterized from the marine toad, Bufo marinus (family Bufonidae; this study), the spadefoot toad, Spea multiplicatus (family Pelobatidae), the African clawed frog, Xenopus laevis (family Pipidae) and the laughing frog, Rana ridibunda (family Ranidae). In these analyses the sequence of Australian lungfish POMC was used as the outgroup. The analyses were done at the amino acid level using the maximum parsimony algorithm and at the nucleotide level using the maximum likelihood algorithm. For the anuran POMC genes, analysis at the nucleotide level using the maximum likelihood algorithm generated a cladogram with higher bootstrap values than the maximum parsimony analysis of the POMC amino acid data set. For anuran POMC sequences, analysis of nucleotide sequences using the maximum likelihood algorithm would appear to be the preferred strategy for resolving phylogenetic relationships at the family taxonomic level.

Amino Acid Sequence↗
PubMed2002

Consequences of intrauterine growth restriction on ventilatory and thermoregulatory responses to asphyxia and hypercapnia in the newborn guinea-pig.

The purpose of this study was to determine the effects of prenatal growth restriction on the ventilatory and thermoregulatory responses to asphyxia and hypercapnia in the newborn guinea-pig. Spontaneously growth-restricted (SGR) animals born to unoperated dams, and growth-retarded (GR) neonates born to dams in which a uterine artery had been ligated at mid gestation, were studied and compared with control neonates. Ventilatory responses to progressive asphyxia and steady-state hypercapnia were tested at 3-6 days of age using a barometric plethysmograph. The animals were then killed and the brains prepared for histological and immunohistochemical analysis. During progressive asphyxia, SGR neonates (n = 5) had a significantly increased minute ventilation compared with both control (n = 6) and GR (n = 5) neonates. Rectal temperature fell significantly in GR and SGR neonates after progressive asphyxia, but was unchanged in control neonates. The ventilatory responses to steady-state hypercapnia were not different in the GR, SGR and control neonates. The immunoreactive expression of glial fibrillary acidic protein, tyrosine hydroxylase, substance P and met-enkephalin in the medulla was also not different between the three groups. It was concluded that prenatal growth restriction is associated with alterations in the respiratory and thermoregulatory responses to asphyxia and hypercapnia, with greater effects observed when in utero growth restriction arises spontaneously, compared with that produced experimentally over approximately the last half of gestation.

Animals↗
PubMed2002

Characterization of H5N1 influenza viruses that continue to circulate in geese in southeastern China.

The H5N1 influenza virus, which killed humans and poultry in 1997, was a reassortant that possibly arose in one type of domestic poultry present in the live-poultry markets of Hong Kong. Given that all the precursors of H5N1/97 are still circulating in poultry in southern China, the reassortment event that generated H5N1 could be repeated. Because A/goose/Guangdong/1/96-like (H5N1; Go/Gd) viruses are the proposed donors of the hemagglutinin gene of the H5N1 virus, we investigated the continued circulation, host range, and transmissibility of Go/Gd-like viruses in poultry. The Go/Gd-like viruses caused weight loss and death in some mice inoculated with high virus doses. Transmission of Go/Gd-like H5N1 viruses to geese by contact with infected geese resulted in infection of all birds but limited signs of overt disease. In contrast, oral inoculation with high doses of Go/Gd-like viruses resulted in the deaths of up to 50% of infected geese. Transmission from infected geese to chickens occurred only by fecal contact, whereas transmission to quail occurred by either aerosol or fecal spread. This difference is probably explained by the higher susceptibility of quail to Go/Gd-like virus. The high degree of susceptibility of quail to Go/Gd (H5N1)-like viruses and the continued circulation of H6N1 and H9N2 viruses in quail support the hypothesis that quail were the host of origin of the H5N1/97 virus. The ease of transmission of Go/Gd (H5N1)-like viruses to land-based birds, especially quail, supports the wisdom of separating aquatic and land-based poultry in the markets in Hong Kong and the need for continued surveillance in the field and live-bird markets in which different types of poultry are in contact with one another.

Animals↗
PubMed2002

Site and mechanism of action of dynorphin A-(1-13) and N-methyl-D-aspartate on ACTH release in fetal sheep.

Dynorphin A (Dyn A) stimulates the release of ACTH in fetal sheep, a response that involves N-methyl-D-aspartate (NMDA) receptors but not the secretogogues corticotropin-releasing hormone or arginine vasopressin. We now find that neither Dyn A-(1-13) (0.5 mg/kg, i.v.) nor NMDA (4 mg/kg, i.v.) elicits ACTH release in postnatal lambs. This led us to hypothesize that Dyn A-(1-13) and NMDA might act to release placental ACTH. However, the ability of Dyn A-(1-13), NMDA, and the kappa-opioid receptor agonist U-50488H (1 mg/kg, i.v.) to release ACTH was lost after either fetal hypophysectomy (n = 4) or hypothalamo-pituitary disconnection (n = 4). These results indicate that neither the placenta nor the fetal pituitary is the site of action for these agonists and suggest a hypothalamic or suprahypothalamic site of action. Furthermore, the release of ACTH by Dyn A-(1-13) and NMDA was abolished after pretreatment with indomethacin, suggesting that they might cause the release of a prostanoid, possibly from the placenta, that subsequently acts at the hypothalamus or serves as a permissive factor in the action of Dyn A-(1-13) and NMDA at the hypothalamus.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed2002

Identification of a fourth opioid core sequence in a prodynorphin cDNA cloned from the brain of the amphibian, Bufo marinus: deciphering the evolution of prodynorphin and proenkephalin.

In mammals, prodynorphin codes for three C-terminally extended forms of leu-enkephalin. This is not the case for the anuran amphibian, Bufo marinus. A combination of 3'RACE, RT-PCR and 5'RACE protocols was used to clone and characterize a prodynorphin cDNA from the brain of this amphibian that contained two met-enkephalin sequences. One met-enkephalin sequence was located at the N-terminal of Met(5)-dynorphin A(1-17), and the other met-enkephalin sequence was located in the N-terminal region of B. marinus prodynorphin in a position that aligned with a pentapeptide met-enkephalin site in mammalian proenkephalin. The latter B. marinus met-enkephalin sequence is flanked by sets of paired basic proteolytic cleavage sites. In addition to the extra met-enkephalin sequence and the Met(5)-dynorphin A(1-17) sequence, the B. marinus prodynorphin contained two C-terminally extended forms of leu-enkephalin [alpha-neo-endorphin and dynorphin B(1-13)]. In the toad precursor the alpha-neo-endorphin sequence is identical to human alpha-neo-endorphin. The B. marinus dynorphin B(1-13) sequence differs from human dynorphin B(1-13) by one amino acid (Thr(12) vs. Val(12)). Steady-state analysis suggests that dynorphin B(1-13) and possibly alpha-neo-endorphin may be cleaved to yield leu-enkephalin as an end-product in the amphibian brain. Finally, the alignment of the extra met-enkephalin sequence in the N-terminal of B. marinus prodynorphin with the corresponding met-enkephalin site in mammalian proenkephalin adds support to the hypothesis that the prodynorphin gene arose as a duplication of the proenkephalin gene.

Acetylation↗
PubMedDate not supplied

Nasal carcinoma--a rare indication for a permanent pacemaker.

Cardiac sinus syncope is a recognised but rare complication of head and neck cancers. Although electrical pacing remains an important treatment to prevent further syncopal episodes related to bradycardia, vasopressor-related syncope remains a more difficult management problem. The article describes the case of a 66-year-old patient with metastatic squamous cell carcinoma of the nose, who presented with syncope and exhibited carotid sinus syncope related to both carotid body invasion and vasopressor mechanisms. Successful management by the insertion of a permanent pacemaker is described, and a review of the literature on this rare complication is given.

Aged↗