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Biomedical subjects

A Parton

Publications and source records attributed to A Parton.

12 recordsLinked to original sources
PubMed2006

Visual neglect after right posterior cerebral artery infarction.

OBJECTIVES: To investigate the characteristics and neuroanatomical correlates of visual neglect after right-sided posterior cerebral artery (PCA) infarction. METHODS: 15 patients with acute PCA strokes were screened for the presence of neglect on a comprehensive battery of cognitive tests. Extra tests of visual perception were also carried out on six patients. To establish which areas were critically associated with neglect, the lesions of patients with and without neglect were compared. RESULTS: Neglect of varying severity was documented in 8 patients. In addition, higher-order visual perception was impaired in 5 of the 6 patients. Neglect was critically associated with damage to an area of white matter in the occipital lobe corresponding to a white matter tract connecting the parahippocampal gyrus with the angular gyrus of the parietal lobe. Lesions of the thalamus or splenium of the corpus callosum did not appear necessary or sufficient to cause neglect, but may mediate its severity in these patients. CONCLUSIONS: PCA stroke can result in visual neglect. Interruption of the white matter fibres connecting the parahippocampal gyrus to the angular gyrus may be important in determining whether a patient will manifest neglect.

Aged↗
PubMed2006

Detection of Enterobacter sakazakii in dried infant milk formula by cationic-magnetic-bead capture.

Enterobacter sakazakii has been associated with life-threatening infections in premature low-birth-weight infants. Contaminated infant milk formula (IMF) has been implicated in cases of E. sakazakii meningitis. Quick and sensitive methods to detect low-level contamination sporadically present in IMF preparations would positively contribute towards risk reduction across the infant formula food chain. Here we report on the development of a simple method, combining charged separation and growth on selective agar, to detect E. sakazakii in IMF. This protocol can reliably detect 1 to 5 CFU of E. sakazakii in 500 g of IMF in less than 24 h.

Bacteriological Techniques↗
PubMed2005

Cognitive processes in saccade generation.

The analysis of saccades offers an opportunity to study a number of different cognitive processes, such as visuospatial attention, working memory, and volitional conflict. A study of saccades in patients with visuospatial hemineglect, who performed a visual search task, showed repeated fixations on targets previously discovered, yet they often failed to retain the information that a particular target had previously been discovered. High-resolution structural brain scanning showed that this abnormality was due either to a lesion in the right intraparietal sulcus or the right inferior frontal lobe. Detailed analysis of the scanpaths suggested that the former location was associated with an accumulating impairment in remapping target locations across saccades or impaired memory of previously inspected target locations, whereas the latter location was more consistent with a failure to inhibit responses to rightward locations. When combined with a spatial bias to the right, such deficits might explain why many neglect patients often reexamine rightward targets, at the expense of items to their left. The functions of the supplementary eye field (SEF), in the medial frontal lobe, in relation to saccade generation are controversial. A series of studies in a patient with a focal lesion of the right SEF has indicated an important role for the SEF in the rapid self-control of saccadic eye movements and in set-switching (i.e., implementing control in situations of response conflict when ongoing saccadic plans have to be changed rapidly), rather than monitoring errors. In a recent fMRI study of normal subjects, it was shown that the SEF is involved in implementing the resolution of any volitional conflict, whereas other presupplementary motor areas are involved in the generation of volitional plans and processing volitional conflict.

Brain Mapping↗
PubMed2004

Hemispatial neglect.

The syndrome of hemispatial neglect is characterised by reduced awareness of stimuli on one side of space, even though there may be no sensory loss. Although it is extremely common, it has proven to be a challenging condition to understand, and to treat. New insights from detailed behavioural and anatomical studies in patients, as well as functional imaging in healthy individuals, have begun to reveal some of the component deficits underlying the disorder. This review focuses on important clinical issues in neglect, including bedside diagnostic tests and emerging therapeutic and rehabilitation methods, involving both behavioural and drug treatments.

Brain↗
PubMed1998

Recovery of Cryptosporidium oocysts from small and large volume water samples using a compressed foam filter system.

A novel filter system comprising open cell reticulated foam rings compressed between retaining plates and fitted into a filtration housing was evaluated for the recovery of oocysts of Cryptosporidium from water. Mean recoveries of 90.2% from seeded small and large volume (100-2000 l) tap water samples, and 88.8% from 10-20 l river water samples, were achieved. Following a simple potassium citrate flotation concentrate clean-up procedure, mean recoveries were 56.7% for the tap water samples and 60.9% for river water samples. This represents a marked improvement in capture and recovery of Cryptosporidium oocysts from water compared with conventional polypropylene wound cartridge filters and membrane filters.

Animals↗
PubMed1996

Assays for microbial contamination and DNA analysis based on electrorotation.

A new assay is described for determining the concentration and viability of waterborne micro-organisms. The method exploits the fact that when a latex bead coated with a specific binding agent is complexed to the target analyte, the analyte complex formed assumes new dielectric properties that can be monitored by its electrorotation response. This generic technology is applicable to a wide range of organism and toxicological diagnostic tests, as well as to other areas of biotechnology. An example is given of its possible application to DNA sequence analysis.

Animals↗
PubMed1993

The hypothalamo-pituitary-adrenal axis across the normal menstrual cycle and in polycystic ovary syndrome.

OBJECTIVE: We explored the hypothesis that activation of the hypothalamo-pituitary-adrenal axis is involved in the pathogenesis of hyperandrogenism in the polycystic ovary syndrome. PATIENTS: Seven women with polycystic ovary syndrome (mean age 27.6 +/- 1.6 (SEM) years) (hirsutism, oligo/amenorrhoea and elevated serum testosterone and dehydroepiandrosterone sulphate) and nine normal female controls (mean age 24.6 +/- 1.5 years) were studied. To exclude anovulation as a confounding factor, four of these normal women were studied in both the follicular and luteal phase of the menstrual cycle. DESIGN AND MEASUREMENTS: Plasma ACTH and cortisol levels were measured at 15-minute intervals between 0600 h and 1800 h. ACTH and cortisol mean levels, pulse number and amplitude were calculated using established computer software, programmed to identify ACTH and cortisol peaks. RESULTS: With the exception of mean plasma levels of ACTH over the 12-hour period, which were reduced in the luteal phase of the menstrual cycle (1.8 +/- 0.3 pmol/l) compared to the follicular phase (2.3 +/- 0.2 pmol/l, P < 0.05), there were no differences in the pattern of ACTH or cortisol secretion across the normal cycle. In polycystic ovary syndrome, 12-hour ACTH pulse frequency was reduced (3.6 +/- 0.7) compared with controls (5.9 +/- 0.6, P < 0.05), but cortisol pulsatility and ACTH and cortisol mean levels were similar in both groups. CONCLUSION: The hyperandrogenism of polycystic ovary syndrome cannot be explained by enhanced ACTH secretion. Normal circulating cortisol levels, yet elevated dehydroepiandrosterone sulphate levels, suggests that polycystic ovary syndrome is yet another example of discrepant adrenal glucocorticoid and androgen secretion, and provides further evidence for a putative adrenal androgen stimulating factor.

Adrenocorticotropic Hormone↗
PubMed1992

Hypothalamic abnormalities in patients with pituitary-dependent Cushing's syndrome.

OBJECTIVE: We aimed to investigate the pattern of 24-hour ACTH and cortisol secretion in pituitary-dependent Cushing's syndrome and to evaluate the pituitary and hypothalamic contributions to the disease. PATIENTS: Five women with Cushing's disease (mean age 35 +/- 5 (SEM) years) and five normal female controls (mean age 25 +/- 2 years) were studied. DESIGN AND MEASUREMENTS: Plasma ACTH and cortisol levels were measured every 15 minutes for 24 hours using established IRMA and RIA respectively. ACTH and cortisol mean and trough levels, pulse number and amplitude were calculated using established computer software, programmed to identify ACTH and cortisol peaks. RESULTS: Patients with Cushing's disease had a twofold increase in 24-hour mean cortisol levels and a threefold increase in 24-hour mean ACTH levels (Cushing's 5.9 +/- 1.0, controls 1.9 +/- 0.2 pmol/l, P less than 0.01). This was predominantly mediated by an increase in ACTH pulse amplitude. However, 24-hour ACTH pulse number was also increased (Cushing's 15.2 +/- 2.6, controls 10.6 +/- 1.7, P less than 0.05) due to an increase in pulse number between 1800 and 2400 h. ACTH trough levels were also higher in patients with Cushing's disease (Cushing's 5.3 +/- 1.3, controls 2.3 +/- 0.2 pmol/l, P less than 0.05). CONCLUSIONS: Twenty-four-hour mean plasma cortisol and ACTH levels are elevated two to three-fold in patients with Cushing's disease. The increase in ACTH pulse amplitude suggests a pituitary abnormality in patients with Cushing's disease. However, the increased ACTH pulse frequency together with elevated trough levels is interpreted as indicating coexisting hypothalamic stimulation (or loss of inhibition).

Adrenocorticotropic Hormone↗
PubMed1990

Detection of novel splicing patterns in a HPV16-containing keratinocyte cell line.

The W12 cell line was derived from a low grade cervical lesion, and is unique among HPV16-containing cell lines in carrying its HPV16 genome as a multicopy episome. As such it is thought to be more representative of a premalignant HPV16-induced tumor than the cervical cancers from which other cell lines have been derived. Using the polymerase chain reaction (PCR), we report here the identification and cloning of a number of novel cDNA species, which appear to be characteristic of the W12 cell line. Two species were identified with E6* coding capacity (E6*I and E6*III). The smaller of these (1009 bp) was predicted to encode a novel E6*III polypeptide containing C-terminal amino acids derived from an out of frame region of the E2/E4 ORFs. The larger species (1480 bp) contained, in addition to the E6*I ORF, an intact E7 ORF and probably represents the transcript for E7 expression, as the E7 protein was readily detectable in the W12 cell line. Both species appeared to be transcribed from the p97 promoter which has been shown to be active in other cell lines. A putative E2 repressor cDNA (891 bp), an E1/E4 message (883 bp), and two novel late cDNA species (1757 and 2031 bp) were also detected, allowing the identification of a splice acceptor immediately in front of the L1 open reading frame (nt 5637) and a splice donor at nt 3631. Although the 1757-base species has the capacity to encode a full-length L1 protein, both messages use a splice donor at nt 1301, and are thus not analogous to late species previously identified in HPV11. Of the six cDNAs cloned, only the 1480-bp E7 message has been observed in other HPV16-containing cell lines. The presence of L1 transcripts, and an E2 repressor mRNA, although unexpected, may reflect the different origins of the W12 cell line.

Amino Acid Sequence↗
PubMed1990

Integrated HPV 1 genomes in a human keratinocyte cell line can be transactivated by a SV40/BPV1 recombinant virus which expresses BPV1 E2 proteins.

This paper describes studies carried out on an HPV 1 carrying human keratinocyte cell line (SVD2) and two subclones of it. Although these lines contain multiple copies of HPV 1 genomes, in situ hybridization revealed that integration was restricted to band q33 on the long arms of chromosome 2. An E4 1.25-kb mRNA was specifically identified by Northern blotting and a PCR generated cDNA confirmed the presence of the E1/E4 spliced mRNA which is abundant in HPV 1 containing papillomas. Infection of an SVD2 subclone (SVD2 (cyst) sp) with a SV40/BPV1 recombinant virus which expresses the BPV1 E2 48-kb transactivator protein enhanced HPV 1 transcription at least 20-fold.

Cell Line, Transformed↗
PubMed1990

The expression of the adenovirus 12 early region 1B 19K protein using a recombinant simian virus 40 system.

Using a simian virus 40/adenovirus 12 (Ad12)-recombinant virus, the Ad12 early region 1B (E1B) 19K protein has been produced at high levels after infection of Cos 1 cells. Expression of the 19K polypeptide reaches a maximum at about 48 h post-infection, declining at later times as host cell death occurs. Using two-dimensional isoelectric focusing/SDS-polyacrylamide gel electrophoresis, we have shown that the Ad12 E1B protein is a major species following infection of Cos 1 cells with recombinant virus. Two forms of 19K polypeptide can be distinguished following isoelectric focusing. Using subcellular fractionation of infected cells, it was found that a similar distribution of 19K protein occurred after recombinant virus and Ad12 infection, with the polypeptide being most abundant in nuclear and membranous fractions. Similarly, as in Ad12-infected cells, a certain proportion of the protein is located on the outside surface of the cell after recombinant viral infection. Immunohistochemical studies suggest that, at early times post-infection, the E1B 19K protein is located in the nuclear membrane, the Golgi apparatus and the endoplasmic reticulum. At later times, it can be seen to have spread to the cytoplasm as well as to the other organelles. These results are discussed in relation to the known functions of the 19K E1B protein.

Adenoviridae↗