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Biomedical subjects

N J Cook

Publications and source records attributed to N J Cook.

At least 19 recordsLinked to original sources
PubMed2006

The use of digital video recorders (DVRs) for capturing digital video files for use in both The Observer and Ethovision.

Before switching a laboratory from analog to digital, for the recording of video files for use in Noldus software such as Ethovision and The Observer, researchers need to proceed with caution. There are obvious advantages in moving to digital recording for behavioral work, including increased storage capacity; no requirement to purchase video tapes; immediate search by date, time, or event; digital images are of higher quality; ability to view study sites remotely by Internet connection; and "smart" features, such as motion detection. But before you throw away your time-lapse video recorders, time code generators, and video multiplexors, there are some important cautions to take account of. Some research groups have bought digital surveillance systems on the assumption that they work with Ethovision and The Observer, only to be disappointed. The vast majority of systems depend on proprietary compression software that must then be converted to work properly in Ethovision or The Observer.

Animals↗
PubMed1999

Paraspinal abscess following facet joint injection.

Injection to the zygapophysial joint is a procedure which is performed frequently for diagnostic or therapeutic reasons in the management of back pain. It is generally considered to be free of significant complications. We report a patient who developed a paraspinal abscess following a lumbar facet joint injection.

Abscess↗
PubMed1999

Adrenocorticotropic hormone increases hydrolysis of B-6 vitamers in swine adrenal glands.

Shipping stress is an economic problem because of its effect on meat quality. Because shipping increases plasma cortisol and pyridoxal 5'-phosphate interacts with steroid hormones, we examined the interaction between adrenocorticotropic hormone (ACTH) and vitamin B-6 metabolism in pigs. Six crossbred pigs with ear vein catheters received 50 IU of porcine ACTH intravenously at 3-h intervals from 0800 to 2100 h on d 1-3 and 100 IU intramuscularly at 0800, 1400 and 2000 h on d 6 and 7. Controls received saline. ACTH had no effect on pyridoxal 5'-phosphate in adrenal tissue but decreased pyridoxamine 5'-phosphate from 6.1 +/- 0.7 to 4.7 +/- 1.0 nmol/g (P < 0.05). Adrenal pyridoxal and pyridoxamine concentrations were 0.4 +/- 0.1 nmol/g in controls and 1.1 +/- 0.3 and 1.3 +/- 0.5 nmol/g, respectively, in ACTH-treated pigs (P < 0.01). Pyridoxal 5'-phosphate phosphatase activity [median (25-75 percentile value)] at pH 7.4 in adrenal tissue was 66.6 (47.8-75.5) nmol/(g. min) in the controls and 764 (626-771) in the ACTH-treated pigs (P < 0.01). There was no significant difference in pyridoxal kinase activity. However, kinase activity in the adrenals was about twice as high as in other tissues. These data suggest an active turnover of vitamin B-6 in adrenal tissue.

Adrenal Glands↗
PubMed1998

Characterization of the glycosyltransferase enzyme from the Escherichia coli K5 capsule gene cluster and identification and characterization of the glucuronyl active site.

Bacterial capsular polysaccharides play an important role in virulence and survival. The Escherichia coli K5 capsule consists of a repeat structure of -4)GlcA-beta(1,4)-GlcNAc alpha(1-, identical to N-acetylheparosan. A 60-kDa protein, KfiC, has been identified as a bifunctional glycosyltransferase, responsible for the alternating alpha and beta addition of each UDP-sugar to the nonreducing end of the polysaccharide chain. Using hydrophobic cluster analysis, a conserved secondary structure motif characteristic of beta-glycosyltransferases was identified along with two highly conserved aspartic acid residues at positions 301 and 352 within the KfiC protein. Site-directed mutagenesis was used to identify catalytically active amino acids within domain A of the KfiC protein. The conserved aspartic acid residues at 301 and 352 were shown to be critical for the beta addition of UDP-GlcA (uridine diphosphoglucuronic acid) to defined nonreducing end oligosaccharide acceptors, suggesting that these conserved aspartic acid residues are catalytically important for beta-glycosyltransferase activity. A deleted derivative of the kfiC gene was generated, which encoded for a truncated KfiC (kfiC') protein. This protein lacked 139 amino acids at the C terminus. This enzyme had no UDP-GlcA transferase activity but still retained UDP-GlcNAc transferase activity, indicating that two separate active sites are present within the KfiC protein.

Amino Acid Sequence↗
PubMed1996

Evaluation of high volume extracapsular cataract extraction with posterior chamber lens implantation in Sierra Leone, west Africa.

AIMS: Intraocular lens (IOP) implantation in sub-Saharan Africa is not the routine procedure of choice in the treatment of cataract. Previous series consist of small numbers of selected patients. The purpose of this study was to evaluate routine posterior chamber lens implantation in large numbers of consecutive patients. METHODS: 1059 cataract extractions with planned IOL (744 patients) were performed over a 1 year period from August 1993 to July 1994. RESULTS: 94.6% (1002) of eyes showed an improvement in visual acuity. A postoperative uncorrected acuity of 6/18 or better was attained in 41.7% of eyes, while 27.1% attained an uncorrected acuity of < 6/18 to 6/60. The commonest operative complication was posterior capsule rupture (11.4%). CONCLUSION: Extracapsular cataract extraction with posterior chamber lens implantation, performed in a well equipped clinic, can give satisfactory results in a developing country. Uncorrected visual acuity can be taken as an acceptable endpoint in the majority of cases.

Adult↗
PubMed1995

Oestradiol measurement in women on oral hormone replacement therapy: the validity of commercial test kits.

Four commercially available methods for the measurement of oestradiol were used to assay oestradiol concentrations in samples from women receiving oral hormone replacement therapy. Significant differences in results were found between samples that were measured direct and those subjected to an extraction procedure. There was considerable variability in the extraction: direct ratio between methods, indicating that with some methods an extraction procedure should be performed before analysis on samples from women receiving oral hormone replacement therapy. Factors that account for discrepant results between methods probably include increased concentration of sex hormone binding globulin together with cross-reacting metabolites and conjugates.

Administration, Oral↗
PubMed1994

Spontaneous resolution of pterygium by auto-avulsion.

The exact pathogenesis of pterygia is not yet clearly understood. Most recent studies implicate fibroblastic proliferation as the essential histopathology in the condition. A case is presented in which spontaneous avulsion of the head of a pterygium occurred, with rapid resolution of symptoms. Such an avulsion suggests the presence of strong forces being exerted on the cornea by the pterygium. Fibroblastic activity could be responsible for the development of such forces. This case supports existing evidence for the primary nature of fibroblastic proliferation in the development of pterygia.

Aged↗
PubMed1994

Incidence, prevalence and possible risk factors for pneumonitis in patients with rheumatoid arthritis receiving methotrexate.

OBJECTIVE: Methotrexate (MTX) is being used increasingly to treat rheumatoid arthritis (RA). Pneumonitis is a serious side effect of MTX therapy (P-MTX). Our aim was to determine in patients with RA the incidence and prevalence of P-MTX in Western Australia and identify risk factors for the development of this adverse reaction. METHODS: Patients with P-MTX were identified by (a) direct communication with rheumatologists in Western Australia, (b) use of a computerized clinical database, (c) questionnaire inquiry of all other rheumatologists in Australia. Possible risk factors for P-MTX were examined using age/sex matched case controls selected from the computerized clinical database. RESULTS: Ten definite and 3 probable cases of P-MTX were identified. Local incidence of P-MTX was 1/35.4 patient years MTX treatment; if definite and probable cases are included (1/49.6 patient years MTX treatment for definite cases alone). Twelve patients with P-MTX were compared with 24 age/sex matched controls. A shorter duration of MTX treatment and a higher incidence of preexisting lung disease were observed in P-MTX cases but these differences were not statistically significant. No difference was observed between the P-MTX and control patients with respect to rheumatoid factor, duration of RA, use of tobacco, dose of MTX, serum creatinine, creatinine clearance or concurrent treatment with aspirin, nonsteroidal antirheumatic drugs or prednisolone. CONCLUSION: Our results indicate that in hospital clinic patients with RA pneumonitis is a common adverse reaction. They suggest that hypersensitivity is probably responsible for most cases of pneumonitis associated with MTX, but preexisting lung disease may confer increased risk.

Aged↗
PubMed1993

Baculovirus-mediated expression of human 65 kDa and 67 kDa glutamic acid decarboxylases in SF9 insect cells and their relevance in diagnosis of insulin-dependent diabetes mellitus.

cDNAs coding for the full-length human 65 and 67 kDa glutamic acid decarboxylases (GAD65 and GAD67) were amplified from pancreas and hippocampus cDNA libraries by polymerase chain reaction, respectively. Both cDNAs were inserted into a baculovirus vector which mediated highly efficient expression of the human GAD65 and GAD67 with histidine-hexapeptides as affinity ligands at their C-termini in Spodoptera frugiperda (Sf9) cells. The recombinant GAD proteins were purified to homogeneity by affinity chromatography using a metal-chelating matrix. The infected Sf9 insect cells expressed the recombinant human GAD65 and GAD67 with natural-like conformations, as confirmed by measurement of their enzyme activities as well as their fully restored autoantigenicities. Immunoprecipitation of metabolically labeled infected Sf9 cells demonstrated the autoantigenic potential of the recombinant GAD proteins. The practicability of using recombinant GAD65 and GAD67 derived from the baculovirus expression system for the development of an immunoassay for the diagnosis of insulin-dependent diabetes mellitus is discussed.

Animals↗
PubMed1993

Features of systemic sclerosis (scleroderma) in an identical twin pair.

The aetiology of systemic sclerosis (scleroderma) is unknown but it is thought to have both genetic and environmental components. The familial incidence of the disease is very low and we have been able to find only one report of scleroderma in identical twins which was in the Russian literature. We report here on a set of identical twins and their mother who all had features of systemic sclerosis.

Adolescent↗
PubMed1993

Expression of recombinant human thyroid peroxidase by the baculovirus system and its use in ELISA screening for diagnosis of autoimmune thyroid disease.

The cDNAs coding for human full-length and soluble thyroid peroxidase (TPO) were constructed, cloned into a baculovirus transfer vector and used for infection of Spodoptera frugiperda (Sf9) cells. The soluble TPO lacking 87 amino acids of the C-terminal transmembrane and intracisternal domains was designed as a fusion protein with a histidine-hexapeptide as an affinity ligand at its C-terminus. Whereas the recombinant full-length TPO was expressed mainly in an insoluble form in Sf9 cells, the recombinant soluble TPO was almost completely secreted into the culture medium. Both the full-length and the soluble TPO were purified by conventional methods and by a specific affinity chromatography using metal chelating matrix respectively, and tested for their autoantigenicity towards anti-TPO autoantibodies. The ELISA established with the purified recombinant soluble TPO as antigen demonstrated its specificity, practicability and reproducibility in screening of anti-TPO autoantibodies in sera of autoimmune thyroid patients. High correlation (r = 0.89, n = 175) was obtained between the soluble TPO and natural TPO prepared from human thyroid glands. Pathological sera (n = 200) were positively assayed with a significance of 91%.

Animals↗
PubMed1992

The cGMP-gated channel of rod outer segments is not localized in bipolar cells of the mammalian retina.

It has recently been suggested (Nature, 346 (1990) 269-271) that ON-bipolar cells express the same biochemical cascade and guanosine 3',5'-cyclic monophosphate (cGMP)-gated cation channel as rod outer segments. An antibody directed against the cGMP-gated channel of bovine rod outer segments was applied to cryostat sections of rat and cat retinae. No immunocytochemical labelling was found in bipolar cells. Therefore, if those cells express a cGMP-gated channel, it must be immunologically different to the 63 kDa protein constituting the cGMP-gated channel of the outer segment.

Animals↗
PubMed1992

Antibodies against synthetic peptides used to determine the topology and site of glycosylation of the cGMP-gated channel from bovine rod photoreceptors.

Peptides corresponding to amino acids 321-339 (peptide GS21) and 416-431 (peptide GS31) of the cGMP-gated channel from bovine rod photoreceptors were synthesized and used as antigens for the preparation of polyclonal antibodies. After affinity purification, both antipeptide antibodies were found to bind specifically to the channel protein after Western blotting, but only the antibody against GS21 gave satisfactory results on enzyme-linked immunosorbent assay and electron microscopy. Using immunocytochemistry, we were able to localize amino acids 321-339 to the extracellular side of the rod photoreceptor plasma membrane. By synthesizing heptapeptides corresponding to amino acids 324-330 (peptide GS2s) and 420-426 (peptide GS3s), we were able to affinity purify antibodies specific for two N-glycosylation consensus sites in the channel protein. As assessed by Western blotting, antibodies against GS3s were found to bind to both the glycosylated and deglycosylated channel proteins, whereas antibodies against GS2s only bound to the channel protein after enzymatic deglycosylation. Together, these results allow the refinement of folding models for the cGMP-gated channel and implicate Asn-327 as being the sole site of N-glycosylation.

Amino Acid Sequence↗