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K Sanderson

Publications and source records attributed to K Sanderson.

35 records · Page 2Linked to original sources
PubMed1997

The hemorphins: a new class of opioid peptides derived from the blood protein hemoglobin.

Hemorphins are endogenous peptides belonging to the family of "nonclassical" or "atypical" opioid peptides. They are generated by enzymatic hydrolysis of the beta-, kappa-, delta-, or epsilon-chain of the blood protein hemoglobin. Originally, the hemorphins were isolated from enzymatically treated bovine blood. In recent years hemorphin structures have been identified as naturally occurring peptides in brain, plasma, and cerebrospinal fluid. This article will review recent studies of the hemorphins regarding their structures, mechanisms for their release, and their biological actions. A particular emphasis will be directed to their role in exercising human and their clinical relevance.

Amino Acid Sequence↗
PubMed1997

Aeromonas spp. possess at least two distinct type IV pilus families.

Type IV pili have been purified from strains of most of the Aeromonas species associated with gastroenteritis (A. veronii biovar sobria, A. hydrophila, A. trota and A. caviae). They appear to be a related family (molecular mass of pilin 19 to 23 kDa) with a tendency to bundle-formation. Hence, we have designated them 'bundle-forming pili' (Bfp). A type IV pilus biogenesis gene cluster (tapABCD) recently cloned from a strain of A. hydrophila, however, encoded a 17 kDa pilin which differed significantly in its N-terminal amino acid sequence from the Bfp pilins. This paper describes the cloning of part (tapA and approximately 20% of tapB) of a homologous pilin gene cluster from a Bfp-positive strain of A. veronii biovar sobria, and presents evidence that the entire pilin gene cluster (tapABCD) is present in this strain. The predicted N-terminal amino acid sequence of the pilin encoded by the A. veronii biovar sobria tapA differed markedly from the corresponding sequence of its Bfp pilin, and those of the Bfp purified from other Aeromonas strains and species. Probing with tapA and tapD genes showed that these Bfp-positive Aeromonas strains also possessed the Tap gene cluster. TapA proteins of A. veronii biovar sobria and A. hydrophila shared 53% identity and 63% homology. We conclude that Aeromonas species are potentially able to express at least two distinct families of type IV pili (Bfp and Tap).

Aeromonas↗
PubMed1997

Plasmids and Aeromonas virulence.

Most putative virulence determinants of Aeromonas species are chromosomally encoded. However, several recent reports have indicated that some may be carried on or regulated by plasmids. Therefore, we examined the plasmid carriage rate of a total of 140 clinical and environmental Aeromonas isolates. Plasmid carriage was compared with the ability of an isolate to produce toxins and adhere to HEp-2 cells. Overall, plasmid incidence in Aeromonas species was low (23/140, 16%) and independent of the source of the isolate. Plasmids were, however, more common in environmental isolates of A. veronii biovar sobria than in clinical isolates of this species (P < 0.05). We could find no evidence to support the recent literature findings that plasmids may have a role in Aeromonas virulence.

Aeromonas↗
PubMed1996

In vitro metabolism of LVV-hemorphin-7 in human plasma studied by reversed-phase high-performance liquid chromatography and micro-electrospray mass spectrometry.

In these experiments we have studied the in vitro metabolism of LVV-hemorphin-7 in human plasma by using reversed-phase high-performance liquid chromatography (RP-HPLC) in combination with micro-electrospray mass spectrometry (micro-ES-MS). Tandem mass spectrometry (MS-MS) was performed in order to verify the structure of the peptide fragments found. Incubations were performed with and without different protease inhibitors. Results showed that LVV-hemorphin-7 was metabolized from the N-terminal end of the peptide, probably by an amastatin-sensitive exopeptidase.

Amino Acid Sequence↗
PubMed1996

Isolation of haemorphin-related peptides from filter membranes collected in connection with haemofiltration of human subjects.

This paper describes the extraction and isolation from dialysis filters of two peptides containing the opioid active sequence haemorphin-7. The filter devices were obtained from uraemic patients subjected to haemofiltration. Following acidic extraction of the filter membranes the peptides were purified by size-exclusion, ion-exchange chromatography and finally by reversed-phase chromatography using different columns and different chromatographic systems. The purification was guided by radioimmunoassay and the structure of the final products was elucidated by N-terminal sequencing and fast-atom bombardment mass spectrometry as well as micro-electrospray mass spectrometry. The isolated peptides were suggested to be identical to fragments 1-41 and 32-41 of the beta-chain of human haemoglobin.

Amino Acid Sequence↗
PubMed1996

Characterization of a type IV bundle-forming pilus (SFP) from a gastroenteritis-associated strain of Aeromonas veronii biovar sobria.

The colonization mechanisms of enteropathogenic Aeromonas strains are poorly characterized, but recent studies indicate that some filamentous structures are intestinal adhesins. This study describes the purification and characterization of a long, flexible pilus from a gastroenteritis-associated strain of Aeromonas veronii biovar sobria. SDS-PAGE analysis (various conditions) of pili preparations yielded a pilin protein band of approximately 21 kDa. Its N-terminal amino acid sequence was unambiguous and homologous with those of type IV pilins. Immunogold electron microscopy with rabbit antisera produced against this pilin protein (SFP) decorated single pili and rope-like bundles of pili on the bacterial surface. These were seen more frequently on strains grown at 22 degrees C compared with 37 degrees C and in liquid rather than on solid medium. SFP was not detected on any of 104 strains of Aeromonas (different species and sources) from our culture collection, although morphologically similar structures were seen on a number of these strains. This finding and differences among other published amino acid sequences show that Aeromonas type IV pili are antigenically diverse. Bundle-forming type IV 'class B' pili are important in the virulence of other enteropathogenic bacteria. The N-terminal amino acid sequence of the Aeromonas SFP, however, showed closer homology to the type IV 'class A' pilins. Studies are in progress to investigate the role of SFP in Aeromonas virulence.

Aeromonas↗
PubMed1996

Novel Psychrobacter species from Antarctic ornithogenic soils.

Ornithogenic soil is derived from the deposition of the fecal matter of various species of birds and is a major source of nutrient input in the Antarctic marine ecosystem. A significant proportion of microbiota of ornithogenic soil collected from an Adélie penguin colony in eastern Antarctica (Vestfold Hills ice-free zone) consisted of gram-negative, coccoid bacteria identified on the basis of their phospholipid ester-linked fatty acid and lipid class profiles as Psychrobacter strains. Phenotypic, genotypic, and 16S ribosomal DNA phylogenetic analyses revealed that the Antarctic psychrobacters belonged to three distinct groups. Comparisons with Psychrobacter immobilis and Moraxella phenylpyruvica reference cultures isolated from fish, seawater, poultry, and human clinical specimens revealed the relationships of these groups within the genus Psychrobacter. Two of the groups represent the following two novel species: Psychrobacter urativorans sp. nov. (type strain, strain ACAM 534) and Psychrobacter frigidicola sp. nov. (type strain, strain ACAM 304). The third group of strains included members of the previously described species P. immobilis (Juni and Heym 1986). In addition, M. phenylpyruvica (Bøvre and Henriksen 1967) is renamed Psychrobacter phenylpyruvicus comb. nov. (type strain, strain ACAM 535) on the basis of 16S ribosomal DNA phylogenetic data. In general, the genus Psychrobacter could be differentiated from the related genera Moraxella and Acinetobacter by the fact that the members of the genus Psychrobacter are psychrotolerant or psychrophilic and halotolerant, which reflects the ubiquitous distribution of the genus in both marine and terrestrial environments. On the basis of the results of this and previous studies, the genus Psychrobacter is the predominant genus in ornithogenic soils in Antarctica and is diverse.

Antarctic Regions↗
PubMed1996

Colonization of streptomycin-treated mice by Aeromonas species.

Streptomycin-treated adult mice were investigated as a possible model for studying the enteropathogenicity of Aeromonas species. C57BL mice pre-treated with streptomycin (5.0 g/L drinking water, 48 hours) received a single intragastric dose (10(10) bacteria /10.5 mL) of one of six well-characterized, toxin-producing, human diarrhoeal isolates of A. veronii biovar sobria (n = 3) or A. hydrophila (n = 3). Their faeces were examined for Aeromonas for 10 days post-challenge. All strains colonized the antibiotic-treated mice. Colonization did not occur in mice which did not receive streptomycin. Strains of A. hydrophila were recovered in greater numbers than strains of A. veronii biovar sobria, and colonized ( > or = 10(3) cfu/g of faeces) a greater proportion of mice at day 10. Strains of the latter species, however, were more adherent in cell line assays used as models of intestinal adhesion. A. hydrophila strains localized in the large intestine and appeared not to be cell associated. This study, therefore, points to species-related differences in intestinal colonization mechanisms. The streptomycin-treated adult mouse model may prove useful for further investigation of some of these mechanisms. Diarrhoeal symptoms were, however, not produced in this model.

Aeromonas↗
PubMed1994

Reversed-phase high-performance liquid chromatography for the determination of haemorphin-like immunoreactivity in human cerebrospinal fluid.

The haemorphins are opioid peptides derived form the blood protein haemoglobin. This study was focused on the detection and determination of haemorphin-like immunoreactivity in human cerebrospinal fluid (CSF) by reversed-phase HPLC. For this purpose a SMART System, optimized for micropurification, was applied. Prior to application to HPLC, the peptide fraction of the CSF sample was extracted using a reversed-phase silica gel cartridge (Sep-Pak C18). In the HPLC separation, the peptide-like material associated with haemorphin-7 immunoreactivity was recovered and determined using a UV detector. The tryptophan residue present in the haemorphin sequence allowed UV detection at wavelengths (e.g., 276 nm) where interference with other co-eluting peptides lacking this residue is minimized. Recorded levels of haemorphin-like immunoreactivity were compared with those detected by radioimmunoassay.

Amino Acid Sequence↗
PubMed1994

Beta A4(25-35) modulates substance P effect on rat skin microvasculature in aged rats: pharmacological manipulation using SEC-receptor ligands.

The primary constituent of the senile plaque core in Alzheimer's disease (AD) is the beta-amyloid protein (beta A4). A discrete 11 amino acid fragment of the beta A4, beta A4(25-35), has been implicated in mediating in vitro neurotoxicity and an inflammatory response surrounding senile plaques in AD via interaction with the Serpin Enzyme Complex (SEC) receptor. Substance P (SP), a neuropeptide of the tachykinin family and a major mediator of neurogenic inflammation, shows sequence homology to beta A4(25-35) and has been shown to protect against the neurotoxicity of beta-amyloid. SP also competes with beta A4(25-35) for binding to the SEC-receptor. SP neurons have also been found to be depleted in AD. Using a blister model of inflammation in the rat hind footpad, we have examined the effect of beta A4(25-35) and its interaction with SP in rat skin microvasculature and determined age-related changes to these phenomena. In addition, pharmacological manipulation of these responses using SEC-receptor ligands (peptide 105Y and 105C) was also undertaken. Because of the evidence for co-existence and co-release of SP and calcitonin gene-related peptide (CGRP) from the peripheral terminals of sensory nerves, it was of interest to examine the interaction of CGRP with beta A4(25-35) on rat skin microvasculature. beta A4(25-35) (10 microM) was perfused over the base of a blister raised on the hind footpad of anaesthetised young and old rats. This was followed by perfusion of SP (1 microM) or CGRP (1 microM) after Ringer's solution. Relative blood flow was monitored using a Laser-Doppler Flowmeter.(ABSTRACT TRUNCATED AT 250 WORDS)

Amyloid beta-Peptides↗
PubMed1994

Lipid peroxidation as a measure of oxygen free radical damage in the very low birthweight infant.

(ABSTRACTOxygen free radical mediated tissue injury is implicated as a major factor in the pathogenesis of the long term complications seen in the premature infant, and direct evidence of their role in the development of these long term problems is lacking. A prospective observational study of 78% of very low birthweight infants admitted to a level III neonatal intensive care unit in 1992 was undertaken to determine the relationship between lipid peroxidation products, antioxidant activity, and outcome. Lipid peroxidation (malondialdehyde-thiobarbituric acid, MDA-TBA) and antioxidant activity (vitamin E and glutathione peroxidase activity) were measured in 22 very low birthweight infants in the cord blood and the infant's blood at 24 hours, 48 hours, and 1 week of age and correlated with outcome measures. The normal range for these measures was established in the cord blood samples of 48 consecutive healthy full term infants. The concentration of MDA-TBA at 1 week correlated with the number of days of oxygen treatment and number of days of positive pressure ventilatory support. Controlling for gestational age and antenatal complications simultaneously the MDA-TBA concentration remained significantly associated with the number of days of oxygen treatment and the number of days of positive pressure ventilatory support. Glutathione peroxidase was low in the premature and full term infants consistent with the low concentrations of selenium known to be present in southern New Zealand. There was evidence of a quadratic relationship between vitamin E at 1 week and the total number of days of supplementary oxygen requirement, with both high and low values associated with increased oxygen requirement. This association, however, did not remain after controlling for gestational age and antenatal complications. These results support the role of oxygen free radicals in mediating tissue damage associated with the development of chronic lung disease in the premature infant.

Chronic Disease↗
PubMed1990

The reliability of the Pelli-Robson contrast sensitivity chart.

Normative contrast sensitivity (CS) data were obtained using the commercially available Pelli-Robson chart from the dominant eye of 30 young (mean (+/- SD) age 22.5 +/- 4.3 years) and 42 older (mean (+/- SD) age 70.2+/- 6.7 years) subjects with normal healthy eyes. The majority of young subjects were found to have a CS of 1.80 log units or above. The majority of the older subjects were found to have a CS of 1.65 log units or above. CS results were obtained using both sides (A and B) of the Pelli-Robson chart from 30 (15 young and 15 older) of these subjects. These measurements were repeated under identical conditions, 2 weeks later. There was no significant difference between the results from sides A and B of the chart. The CS scores were shown to be repeatable to within +/- 0.15 log units or +/- 1 step. Therefore a significant change in CS score is +/- 2 steps or 0.30 log units. Slight improvements in reliability could be obtained by more careful permutation of letters on each step and a smaller step size. The restriction against these changes is the ensuing increased chart size.

Adult↗
PubMed1984

Claustral afferents to the rat's visual cortex.

Horseradish peroxidase (HRP) was injected electrophoretically into the rat's primary visual cortex (V1), and three other retinotopically organized cortical areas, anterior medial visual area (AM), posterior medial visual area (PM) and anterior lateral area (AL). While the HRP injections into V1 labelled many neurons in the ipsilateral claustrum, the injections in any of the three other visual areas labelled very few claustral neurons.

Afferent Pathways↗
PubMedDate not supplied

Disability measurement in the anxiety disorders: comparison of three brief measures.

General measures of disablement are powerful tools in clinical settings as they provide a link between clinic and community populations and allow cross-disorder comparisons. Because of their generic nature, they allow the transmittal of comprehensible health planning information to decision makers. We located no studies of such general disability measures in the anxiety disorders and decided to examine the properties of three brief generic measures in an anxiety disorders clinic. Consecutive attenders (N=168) were administered the Medical Outcomes Study Short Form-12 item (SF-12), the Brief Disability Questionnaire (BDQ), and a measure of the number of disability days due to health over the past 4 weeks. These measures were compared on their ability to discriminate within the clinic and in comparison to a representative community group. The mental health scale of the SF-12 was the most sensitive of the generic measures to differences in functioning, and is recommended as a measure of such for people with anxiety disorders. Attenders at this anxiety clinic reported high levels of disablement, and normative data on the general measures are provided.

Anxiety Disorders↗