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Biomedical subjects

S Barker

Publications and source records attributed to S Barker.

At least 91 records · Page 5Linked to original sources
PubMed1995

Type 1 angiotensin II receptors in rat and human sperm.

The physiological factors which induce and maintain mammalian sperm maturation and motility generally remain unclear, although several agents are known to be involved. We describe here the application of immunocytochemical and immunoblotting methods to identify the angiotensin II type 1 (AT1) receptor in the tails of ejaculated rat and human sperm. Motility data on stimulated and unstimulated sperm from volunteers and patients attending fertility clinics showed that angiotensin II may increase both the percentage of motile sperm and their linear velocity, while the specific AT1 receptor antagonist DuP753 inhibited the action of angiotensin II on the percentage of motile sperm. In rat seminiferous tubules, AT1 receptors were present in primary spermatogonia and in spermatid tails, but immunoreactivity was not seen in sperm contained in caput or cauda epididymis, showing that AT1 receptor function is regulated during transit through the reproductive tract. Since local tissue reninangiotensin systems are present in both male and female tracts, the data suggest that angiotensin II has a role in the maintenance of sperm function and fertility.

Angiotensin II↗
PubMed1994

A community ability scale for chronically mentally ill consumers: Part II. Applications.

The authors describe uses for a 17-item instrument that efficiently measures the functioning level of chronically mentally ill persons living in the community. The Multnomah Community Ability Scale is designed to be completed by case managers who work with chronically mentally ill consumers. The instrument is sensitive to differences among individuals within this special population of consumers and is easy to complete. Community mental health program staff can be trained to use the scale reliably. The scale has been used to compare levels of severity between urban and rural community mental health program clients. The authors discuss the application of the Multnomah Community Ability Scale to a capitated payment system for severely mentally ill, involuntary clients.

Activities of Daily Living↗
PubMed1994

A community ability scale for chronically mentally ill consumers: Part I. Reliability and validity.

The authors describe the development, reliability testing, and validation of a 17-item instrument that measures the level of functioning of chronically mentally ill persons living in the community. The Multnomah Community Ability Scale is designed to be completed by case managers. The instrument provides a measure of the consumer's severity of disability which can, in turn, be used to: (a) describe an agency's "case mix" of clients; (b) measure consumer progress; (c) assign clients to different levels of service; and (d) assist payors in determining reimbursement. The Multnomah Community Ability Scale is aimed specifically at persons with chronic mental illness, is sensitive to differences among individuals within this special population, and is quick and easy to complete. The scale's reliability and validity have been examined in detail. Inter-rater and test-retest reliability are good. Criterion variables such as length of psychiatric hospitalization and clinicians' global ratings correlated highly with scale scores. Finally, the instrument predicts subsequent state and local hospital admissions.

Activities of Daily Living↗
PubMed1994

Effects of two formats of informed consent on knowledge amongst persons with advanced HIV disease in a clinical trial of didanosine.

To determine subjects' perception of the purpose of informed consent, 113 subjects were recruited from a dose-controlled clinical trial of didanosine (ddI). Subjects were surveyed regarding how they made decisions regarding their medical care in general, about how they obtained information about this trial in particular, and several aspects of the informed consent procedure. Subjects were then randomly allocated to receive information about the trial by either a written only format or a written and verbal format 1 week before commencement of the trial. An eight-item instrument assessed knowledge of ddI prior to and subsequent to receiving information. Most subjects obtained information about HIV-related issues from their specialist (70%) or general (51%) medical practitioner. A large proportion of subjects (88%) reported that they believed their specialist medical practitioner always acted in their best interest. The majority of subjects (79%) believed that subjects should be allowed the choice between participating in the clinical trial and receiving the drug outside the trial mechanism. Of the subjects, 96% believed that informed consent was necessary in clinical trials; however, their opinions of the purpose of informed consent varied widely. Although they signed the informed consent, 44% of the subjects stated that they did not understand 'all' of the information that was provided. We found that the provision of information by written mode alone, or written and verbal modes were both associated with significant increases in knowledge levels and that there was a significant interaction in the degree of change between the two methods, with the written plus verbal method showing the most improvement over time. There was an interaction between degree of improvement in knowledge of didanosine in subjects who received written information versus those who received written and verbal knowledge and time (pre- versus post-consent) and a significant main effect for time. All subjects were relatively well-informed about the drug and stated that specialist and general medical practitioners were their major source of knowledge for all aspects of their HIV health care.

Adult↗
PubMed1994

Vascular complications of elective lower lumbar disc surgery.

Lower lumbar disc surgery is an extremely common operation from which vascular complications are reported rarely. However vascular injury can occur with perforation of the anterior longitudinal ligament. External haemorrhage is uncommon and the true cause of the patient's hypotension may be misdiagnosed. If the hypotension is severe or prolonged laparotomy is indicated, to prevent exsanguination and to effect a repair of the vascular injury. Alternatively, if the injury is missed, an arteriovenous fistula may develop; this diagnosis may be delayed for months or years. One case of severe haemorrhage following lower lumbar disc surgery is reported and a further 69 cases of similar arterial injury have been reviewed from the world literature.

Arteriovenous Fistula↗
PubMed1994

Herpes simplex encephalitis: long term magnetic resonance imaging and neuropsychological profile.

The first comprehensive in vivo documentation of the long term profile of pathological and spared tissue is described in a group of 10 patients with a diagnosis of herpes simplex encephalitis, who were left with memory difficulties as a major residual sequel of their condition. With a dedicated MRI protocol, which included high resolution images of temporal lobe and limbic system areas, data are provided on structures that have recently gained importance as anatomical substrates for amnesia. The major features of the lesion profile were: (1) unilateral or bilateral hippocampal damage never occurred in isolation, and was often accompanied by damage to the parahippocampus, the amygdala, specific temporal lobe gyri, and the temporal poles; (2) the insula was always abnormal; (3) neocortical temporal lobe damage was usually unilateral or asymmetric. It never occurred in isolation, and was invariably associated with more medial pathological changes; (4) anterior and inferior temporal lobe gyri were damaged more often and more severely than posterior and superior temporal lobe gyri; (5) pronounced abnormality was often present in the substantia innominata (region of the basal forebrain/anterior perforated substance); (6) there was evidence of significant abnormality in the fornix; (7) there was evidence of damage to the mammillary bodies; (8) thalamic nuclei were affected in around 50% of cases, with damage usually unilateral; (9) frontal lobe damage was present in a few patients, and affected medial areas more than dorsolateral areas; (10) there was some involvement of the striatum, although this was usually unilateral and mild; (11) there was usually limited involvement of the cingulate gyrus and of the parietal and occipital lobes; (12) the cerebellum and brain stem were never damaged. Lesion covariance analysis indicated a close relation between the presence of abnormalities in temporal lobe and limbic-diencephalic regions. Unlike severe head injury, lesions in the temporal pole were not associated with the presence of lesions in the orbitofrontal cortex. Long term neuropsychological impairments were characterised by a dense amnesia in 60% of cases, and a less serve but noticeable anterograde memory impairment in the others. Naming and problem solving deficits were found in a small number of cases. Only two patients were able to return to open employment. Severity of amnesia showed a significant relation with severity of damage to medical limbic system structures such as the hippocampus, with bilateral damage being particularly important. By contrast, there was a minimal relation between memory loss and severity of damage to the thalamus, to lateral temporal lobe areas, or to the frontal lobes.

Adult↗
PubMed1994

Transient memory loss for people.

A patient had transient memory loss for close family members. She could not even recognise their names as familiar. Her everyday memory was relatively preserved and she retained a clear recollection of the episode. Standard and sleep deprived EEG showed a mild abnormality of the left temporal lobe. Neuropsychological testing found evidence for a mild verbal memory impairment. The findings provide further evidence for the fractionation of transient forms of amnesia, support the dissociation of semantic/retrograde amnesia from episodic/anterograde amnesia, and offer evidence in favour of a left temporal lobe site for retrieval of past memories relating to the identification of people.

Adult↗
PubMed1994

Angiotensin II receptor subtypes in eel (Anguilla anguilla).

Previous studies have shown the effects of angiotensin II (Ang II) in teleosts, and Ang II-binding sites have also been localized in tissues from rainbow trout. The purpose of this study was to extend these findings and to provide an analysis of Ang II receptor (Ang II-R) isoforms in three tissues obtained from European eel (Anguilla anguilla). Ang II-Rs were identified in eel liver, kidney and intestine membranes by the binding of either 0.5 nmol human 125I-labelled Tyr4-Ile5-Ang II/l or increasing concentrations (1-120 nmol/l) of [3,5-3H]Tyr4-Ile5-Ang II. Using an isoelectric focusing technique, two Ang II-binding sites were identified in liver membranes. These migrated to isoelectric points (pI values) 6.5 and 6.7. Seventy per cent of binding to both sites was displaced by a 10,000-fold excess of unlabelled human Ang II. In both whole plasma membranes and brush border membranes from intestine, only one form of the Ang II-R was found, with pI 6.5 and high affinity (Kd = 3.4 nmol/l) for the [3,5-3H]Tyr4-Ile5-Ang II. Similarly, only the isoform focusing at pI 6.5 was observed in renal tubular epithelial brush border membranes. Reduction of disulphide bridges with dithiothreitol significantly enhanced Ang II binding to the isoform at pI 6.5 in liver (P < 0.05) and kidney (P < 0.01), while in liver the binding to the isoform of pI 6.7 was significantly reduced (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Anguilla↗
PubMed1994

Alpha-melanocyte-stimulating hormone-induced inhibition of angiotensin II receptor-mediated events in the rat adrenal zona glomerulosa.

It is well established that ACTH and angiotensin II (Ang II) stimulate aldosterone secretion from rat adrenal zona glomerulosa cells in vitro and mediate their steroidogenic effects via the cyclic AMP (cAMP) pathway and phosphoinositide turnover respectively. alpha-MSH also stimulates aldosterone secretion from zona glomerulosa cells in vitro, and recent studies from our laboratory have shown that its steroidogenic effects are mediated by increases in inositol 1,4,5-trisphosphate (IP3) production. alpha-MSH also stimulates adenylyl cyclase activity, but only at concentrations that are supramaximal for stimulation of steroidogenesis. The observation that alpha-MSH-stimulated IP3 accumulation declines as the activity of adenylyl cyclase increases prompted further studies on the interactions of cAMP and phosphoinositide production. The effects of alpha-MSH and ACTH on Ang II-stimulated steroidogenesis and IP3 accumulation were studied. On addition of increasing concentrations of ACTH, both the aldosterone and IP3 responses to Ang II were significantly inhibited; however, only high concentrations of alpha-MSH achieved this effect. These results suggest that cAMP or a cAMP-dependent event is able to inhibit phospholipase C activity. This hypothesis was tested by measuring IP3 production in Ang II-stimulated zona glomerulosa cells exposed to two different concentrations of alpha-MSH: 1 nmol/l, which stimulates the generation of IP3, and 1 mumol/l, which activates adenylyl cyclase. It was found that this high concentration of alpha-MSH significantly inhibited Ang II-stimulated aldosterone secretion and IP3 levels. In addition, alpha-MSH reduced 125I-labelled Ang II binding to rat adrenal zona glomerulosa cells.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1994

Distribution of the adrenocortical inner zone antigen.

Previous studies using a mouse monoclonal antibody (IZAb) have identified inner zone-specific antigens (IZAg 1 and 2) in the rat adrenal cortex. The expression of IZAg1 is enhanced by dibutyryl-cyclic AMP or ACTH in vitro and by in vivo ACTH treatment. These studies also suggest that IZAg may be involved in steriogenesis in rat adrenals. Using sensitive detection methods, the distribution of IZAg in adrenals from other species and in other rat tissues was studied. Pig and rabbit adrenals expressed an IZAb-immunoreactive protein with molecular mass identical with that of IZAg1, but no immunoreactivity was detected in bovine, guinea-pig or mouse adrenals. In the rabbit adrenal, as in the rat, IZAb bound only to zonae fasciculata/reticularis cells. However, the whole adrenal cortex in the pig immunoreacted with IZAb. Although immunofluorescence was observed in human adrenal sections, predominantly in the zona reticularis, no significant immunoreactive protein band was detected by immunoblot analysis. Apart from the zonae fasciculata/reticularis in the adrenal gland, an IZAb-immunoreactive protein with a molecular mass of 26,000 Da, corresponding to IZAg1, was also found in rat hepatocytes, renal tubules, ovary (corpus luteum, interstitial cells, theca interna of mature follicles) and Leydig cells. The observations suggest that IZAg may be involved in the processes of biosynthesis, metabolism and/or excretion of steroid hormones.

Adrenal Cortex↗
PubMed1994

Internalisation of the type I angiotensin II receptor (AT1) and angiotensin II function in the rat adrenal zona glomerulosa cell.

Little is known about the cellular localisation of the angiotensin II (AII) type 1 receptor (AT1) in the rat adrenal glomerulosa cell, but some studies have suggested that receptor internalisation and recycling may occur. Using a specific monoclonal antibody (6313/G2) to the first extracellular domain, we show here that most of the receptor is internalised in the unstimulated cell. When viable glomerulosa cells are incubated with 6313/G2, the receptor is transiently concentrated on the cell surface, and aldosterone output is stimulated. This stimulated output is enhanced by neither threshold nor maximal stimulatory concentrations of AII amide, although the antibody does not inhibit AII binding to the receptor. Conversely, the stimulatory actions of the antibody and those of ACTH are additive. The data suggest that recycling to the plasma membrane is constitutive, or regulated by unknown factors. Retention of the AT1 receptor in the membrane is alone enough to allow sufficient G protein interaction to generate maximal stimulatory events.

Aldosterone↗
PubMed1993

Enzyme-linked immunosorbent assay of HER-2/neu gene product (p185) in breast cancer: its correlation with sex steroid receptors, cathepsin D and histologic grades.

One hundred and nine primary breast cancers were analyzed to assess the presence of the HER-2/neu gene product (p185), the oestrogen (ER) and the progesterone (PR) receptors, and the total cathepsin D status. An enzyme-linked immunosorbent assay (ELISA kit, Oncogene Science Inc.) was used for the evaluation of p185 in pellets obtained after a 100,000 x g centrifugation, ER and PR were measured by enzyme immunoassay (EIA kit, Abbott Laboratories), and the total cathepsin D content was evaluated by immunoradiometric assay (IRMA kit, CIS Biointernational). We showed that the ELISA kit is feasible to quantify the p185 present in breast cancer cell membranes, and that the detector antibody recognises a protein of apprroximatly M(r) 185,000. The detected antigen was inversely related to both ER and PR, but it did not correlate to total cathepsin D. No significant differences were found in the expression of p185, ER, PR, cathepsin D between infiltrating ductal carcinomas without special features (NOS) and non-ductal (non-NOS) carcinomas. Nevertheless, in NOS carcinomas, a trend was observed in the p185 levels expressed by the tumours with different histological grades, in that p185 concentration was higher in the poorly differentiated grade 3 with respect to grade 2 and grade 1.

Adult↗
PubMed1993

Effect of low molecular weight aliphatic alcohols and related compounds on platelet factor 4 subunit association.

Titration of platelet factor 4 (PF4) with increasing concentrations of various low molecular weight aliphatic alcohols disrupts dimer and tetramer quaternary structure while preserving tertiary structural integrity. Normally observed slow subunit exchange (1H NMR time scale) is shifted into the fast chemical exchange regime. The order of effectiveness is butanol > 2-propanol > propanol > ethanol > methanol. Fluorination of ethanol (trifluoroethanol) and 2-propanol (hexafluoro-2-propanol) increases effectiveness by approximately 2 orders of magnitude. Oxidation to 2-propanone or trifluoro-2-propanone produces a less effective compound, suggesting a mechanistic role for the hydroxyl group. Increasing the number of hydroxyls to three, as in glycerol, however, is relatively ineffective in disrupting aggregate states or modifying subunit exchange rates. While 19F NMR studies indicate that these alcohols specifically interact with PF4, binding alone can not explain their mechanism of action. Dimethyl sulfoxide, structurally similar to 2-propanol, disrupts PF4 aggregation by direct binding, but does not shift subunit exchange kinetics into the NMR fast-exchange regime. Although not fully understood, the effectiveness of these compounds appears to be related to the colligative properties of the solution.

Alcohols↗
PubMed1993

Comparison of COS cell transfected AT1A and AT1B angiotensin II receptors and angiotensin II receptor isoforms in rat tissues using isoelectric focusing.

Rat adrenal AT1A and AT1B receptors from transfected COS-7 cells were labelled with 125I-Angiotensin II, solubilised, and run on isoelectric focusing gels. Receptors from rat tissues were treated similarly. COS-7 cell-expressed AT1A and AT1B receptors each produced a single peak of specific radioactivity at pI 6.8. Rat liver and rat ovary tissue preparations gave peaks at pI 6.8 and 6.5, respectively. In contrast, rat adrenal tissue preparations gave four peaks at pI 7.0, 6.8, 6.5, and 6.3. The additional isoforms found in the rat adrenal tissue preparations may represent post-translationally modified or novel receptors.

Adrenal Glands↗
PubMed1993

Orotracheal intubation in trauma patients with cervical fractures.

OBJECTIVE: To evaluate orotracheal intubation with in-line stabilization of the cervical spine for emergency airway treatment of trauma patients with cervical spine injuries. DESIGN: Of 7518 trauma patients examined, 81 patients with cervical spine injuries received emergency orotracheal intubation. All intubations were performed by experienced anesthesiologists, with a separate individual maintaining in-line stabilization. Neurologic examination was documented before and after intubation. RESULTS: Peripheral neurologic deficit was present from the outset in 20 patients. There were unstable cervical fractures in 38 patients with no neurologic deficit. Twenty-three patients were neurologically intact with fractures that were later judged stable. In no instance was there a deterioration of neurologic status following intubation. Peripheral neurologic deficits improved after intubation in four patients. CONCLUSION: Orotracheal intubation, performed with manual in-line stabilization by trained and experienced personnel, is a safe emergency procedure in patients with cervical fractures.

Accidents, Traffic↗