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Biomedical subjects

S C Martin

Publications and source records attributed to S C Martin.

At least 19 recordsLinked to original sources
PubMed2006

Best practice in primary care pathology: review 8.

This eighth best practice review examines four series of common primary care questions in laboratory medicine: (i) sodium abnormalities; (ii) faecal occult blood testing; (iii) warfarin management; and (iv) sputum cytology in diagnosis of bronchopulmonary malignancy. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Anticoagulants↗
PubMed2004

Coping styles among families of children with HIV infection.

The primary aim of this study was to examine coping strategies among families of HIV-infected children and how they relate to medical, central nervous system (CNS) and family environment factors. Caregivers of HIV-positive children (N=52) completed a family coping measure (F-COPES) and provided information regarding family environment. Data regarding medical and CNS status were obtained from patient records. Results indicated that families' passive coping and spiritual support were among the coping techniques used most often, and social support was used least often. Medical variables were unrelated to any coping styles. Families of children with CNS impairment endorsed more passive coping techniques than families of children with no apparent deficits. A trend was found for non-biological caregivers to seek out more community resources and support than biological caregivers. Findings suggest the need to target families least likely to utilize resources, and to teach them to effectively seek out and benefit from social and community supports.

Adaptation, Psychological↗
PubMed2002

Serum homocysteine concentration is related to diabetes mellitus, but not to coronary heart disease, in Saudi Arabians.

INTRODUCTION: Plasma homocysteine (HCYS) concentration is believed to be an independent risk factor for atherosclerosis. METHODS: HCYS was measured in a cohort of 584 Saudi Arabians participating in a national screening study of coronary heart disease (CHD) risk factors. A total of 173 subjects (114 men and 59 women) had clinical CHD, of whom 82 (47.4%) had type 2 diabetes mellitus (56 men and 26 women). A further 127 subjects (60 men and 67 women) also had type 2 diabetes mellitus but no CHD. A total of 284 individuals (120 men and 164 women) were recruited as healthy controls, and had no previous history of CHD or diabetes. Serum HCYS was measured by high-performance liquid chromatography (HPLC) with electrochemical detection. RESULTS: Univariate analysis showed HCYS concentrations were significantly lower in those with diabetes mellitus (DM) than in controls, for both men [8.7 (4.2-18.6) vs. 10.5 (4.5-20.5) mmol/l, median (5th-95th percentiles, p = 0.009] and women [6.3 (3.3-24.0) vs. 8.1 (4.0-17.9) mmol/l, p = 0.049]. Stepwise multivariate regression analysis indicated a relationship between HCYS concentration and age, sex and the presence of DM, but not with CHD. CONCLUSIONS: In the Saudi Arabian population, serum HCYS is not a risk factor for CHD, but is lower in patients with DM.

Adolescent↗
PubMed2002

Cardiovascular risk assessment in patients with retinal vein occlusion.

AIM: Patients with retinal vein occlusions (RVO) are at increased risk of cardiovascular disease (CVD). The risk of future CVD was determined using the Framingham algorithm and this risk estimate was used to guide decisions about preventative treatment for CVD in RVO patients. METHODS: 107 unselected RVO patients were studied. After excluding 18 patients because of age, missing data, or pre-existing cardiovascular disease, the calculated coronary heart disease risks (cCHDR) and calculated cardiovascular disease risks (cCVDR) were calculated on the 89 remaining and compared with both the standardised risk and the published incidence of CHD in England by t test or chi(2) test. RESULTS: The mean 10 year cCVDR was significantly higher than the Framingham standardised risk for all RVOs (20.6% (1.2%) v 15.7% (1.1%), p = 0.009) and female RVOs (17.8% (1.2%) v 12.7% (1.0%), p = 0.022) in particular. The 10 year cCHDR, compared to the actual incidence of CHD in England between the ages of 30 and 74 years, was > 15% in twice as many males than expected (62% v 28%, p <0.0001). This rose to almost six times when cCHDRs greater than 30% were compared (17% v 3%, p = 0.002). There was a fourfold increase in the proportion of female RVO patients with a cCHDR above 15% (40% v 9%, p <0.0001) and at a cCHDR of 30% and above (10% v 0%, p = 0.004). There were also significant differences in the cCHDR between central and branch RVO (both sexes). The branch form of RVO (BRVO) having higher cCHDRs because of systolic hypertension (164.1 (21.6) mm Hg v 149.5 (23.5) mm Hg, p = 0.003) and age (61.7 (8.3) years v 56.7 (10.6) years, p = 0.017). CONCLUSIONS: RVO is the presenting complaint in a group of patients at increased risk of CVD and is in agreement with the long term follow up data demonstrating an increased mortality from CVD in patients with RVO. The Framingham algorithm can accurately determine the cCHDR (or cCVDR) to assist the clinician in deciding who to treat in accordance with the Joint British Societies' guidelines, with particular regard to hypertension, lipid lowering, and the use of aspirin therapy.

Aged↗
PubMed2001

Human GABA(B)R genomic structure: evidence for splice variants in GABA(B)R1 but not GABA(B)R2.

The type B gamma-aminobutryic acid receptor (GABA(B)R) is a G protein coupled receptor that mediates slow pre- and post-synaptic inhibition in the nervous system. We find that the human GABA(B)R2 gene spans greater than 350 kb and contains 2.8 kb of coding region in 19 exons. The overall similarity in genomic structure with regard to conservation of intron position and exon size between human or Drosophila GABA(B)R1 and GABA(B)R2 genes suggests a common ancestral origin. Multiple transcripts GABA(B)R1a-c and GABA(B)R2a-c have been described and alternative splicing has been proposed to result in GABA(B)R1c, GABA(B)R2b and GABA(B)R2c. The results described here provide support for the existence of GABA(B)R1c but not for GABA(B)R2b and GABA(B)R2c. Splice junctions present in the GABA(B)R1 gene sequence are consistent with the formation of GABA(B)R1c by exon skipping of one sushi domain module. The GABA(B)R2 gene lacks canonical splice junctions for the reported variants. Consistent with this, RNA analysis demonstrates the presence of GABA(B)R1c and GABA(B)R2 transcripts in fetal and adult human brain RNA but GABA(B)R2b and GABA(B)R2c transcripts are not detected. These results provide insight into the evolution and transcript diversity of the mammalian GABA(B)R genes.

Alternative Splicing↗
PubMed2001

A pilot study of homocyst(e)ine levels in essential hypertension: relationship to von Willebrand factor, an index of endothelial damage.

An interaction between homocyst(e)ine and the endothelium in hypertensive patients may promote thrombogenesis and atherogenesis, leading to adverse cardiovascular events. We hypothesized that homocyst(e)ine levels are abnormal in patients with essential hypertension, and that this may be related to an adverse effect on the vascular endothelium. Accordingly, we compared plasma levels of homocyst(e)ine and von Willebrand factor (marking endothelial damage) in 83 patients (43 men; mean age 54 +/- standard deviation 15.9 years) with essential hypertension (> 160/90 mm Hg), with levels in 25 healthy normotensive controls (13 men; mean age 56+/-11.8 years). Baseline levels of the markers and other clinical indices were then related to adverse cardiovascular events at follow-up. Plasma homocyst(e)ine (P = .0001) and von Willebrand factor (P = .031) levels were significantly higher in hypertensives compared to controls. After a mean follow-up of 76 patients for 45 months (range, 1 to 66 months), 17 subjects experienced an end point of either cardiovascular death (n = 10) or adverse cardiovascular event (n = 7). Comparing these 17 with the 59 free of an end point, the former were older (P = .0002) and had a longer duration of known hypertension (P = .018). There was a nonsignificant trend toward higher median plasma homocyst(e)ine levels in the patients sustaining a vascular end point (P = .07). In this pilot study, we suggest that essential hypertension may be associated with increased plasma homocyst(e)ine levels, but that this amino acid is unrelated to endothelial damage (von Willebrand factor), clinical indices, or prognosis.

Adult↗
PubMed2001

Degradation of lignin in wheat straw during growth of the oyster mushroom (Pleurotus ostreatus) using off-line thermochemolysis with tetramethylammonium hydroxide and solid-state (13)C NMR.

The oyster mushroom (Pleurotus ostreatus) is widely cultivated on wheat straw (Triticum aestivum); however, there is a need to better understand the relationship between the chemical composition of the compost and mushroom growth. Wheat straw was degraded over a period of 63 days by P. ostreatus during which time it was sampled at weekly intervals. Off-line thermochemolysis with tetramethylammonium hydroxide and solid-state (13)C NMR were then used in the molecular characterization of the undegraded wheat straw and the degraded samples. The degraded wheat straw samples had a lower proportion of syringyl- to guaiacyl-derived moieties and cinnamyl- to guaiacyl-derived moieties than the undegraded control. There were increases in both guaiacyl and syringyl acid to aldehyde ratios with composting time, which showed that side-chain oxidation has been mediated by P. ostreatus. The (13)C NMR spectra confirmed the increase in carboxyl content but indicated that the overall lignin and methoxyl contents remained relatively constant, although some nonsystematic variations were observed. The spectra also showed a decrease in amorphous noncellulosic polysaccharides in relation to the crystalline cellulose upon degradation.

Carbon Isotopes↗
PubMed2000

Plasma total homocysteine and retinal vascular disease.

PURPOSE: Hyperhomocysteinaemia has been linked to macrovascular disease. Our aim was to investigate whether there is a relationship between fasting plasma total homocysteine levels and retinal vascular disease. METHODS: We measured the homocysteine levels in 70 patients with arterial or venous retinal vessel occlusion and compared them with the levels in 85 controls without evidence of ischaemic heart disease. Homocysteine levels were determined by high-performance liquid chromatography with electrochemical detection and compared after logarithmic transformation. RESULTS: Homocysteine levels were found by univariate analysis (unpaired two-tailed t-test) to be significantly higher in the group with retinal artery occlusion than the group with retinal vein occlusion (p = 0.045) and in both groups compared with controls (18.4 and 13.8 vs 9.5 mumol/l; p = 0.0002 and < 0.0001, respectively). The controls, however, were significantly younger than the subjects (51.5 +/- 15.4 vs 66.2 +/- 11.9 years; p < 0.0001), but analysis of the results by age revealed significant differences between the groups and controls for the seventh decade (vein occlusions, p = 0.05) and for the eighth decade (artery occlusions, p = 0.037). Subgroup analysis of the retinal vessel occlusion group revealed significant differences in mean blood pressure between those with branch retinal vein occlusions (175/100 mmHg) and both those with central retinal vein occlusions (155/88 mmHg) and those with retinal artery occlusions (157/86 mmHg). Both vein occlusion subgroups also differed significantly with regard to homocysteine levels, branch < central (12.2 +/- 1.3 vs 15.0 +/- 1.6 mumol/l, p = 0.03). Multiple linear regression analysis revealed significant relationships between homocysteine levels and the presence of retinal vessel occlusion (p = 0.0002), serum creatinine (p = 0.001) and age (p = 0.003), but not gender. CONCLUSIONS: We conclude that homocysteine may be a risk factor for retinal vascular disease and could be simply and cheaply treated with folate and vitamins B6 and B12.

Adult↗
PubMed1999

Molecular identification of the human GABABR2: cell surface expression and coupling to adenylyl cyclase in the absence of GABABR1.

We have identified a gene encoding a GABAB receptor, the human GABABR2, located on chromosome 9q22.1, that is distinct from the recently reported rat GABABR1. GABABR2 structurally resembles GABABR1 (35% identity), having seven transmembrane domains and a large extracellular region, but differs in having a longer carboxy-terminal tail. GABABR2 is localized to the cell surface in transfected COS cells, and negatively couples to adenylyl cyclase in response to GABA, baclofen, and 3-aminopropyl(methyl)phosphinic acid in CHO cells lacking GABABR1. Baclofen action is inhibited by the GABABR antagonist, 2-hydroxysaclofen. The human GABABR2 and GABABR1 genes are differentially expressed in the nervous system, with the greatest difference being detected in the striatum in which GABABR1 but not GABABR2 mRNA transcripts are detected. GABABR2 and GABABR1 mRNAs are also coexpressed in various brain regions such as the Purkinje cell layer of the cerebellum. Identification of a functional homomeric GABABR2 coupled to adenylyl cyclase suggests that the complexity of GABAB pharmacological data is at least in part due to the presence of more than one receptor and opens avenues for future research leading to an understanding of metabotropic GABA receptor signal transduction mechanisms.

Adenylyl Cyclases↗
PubMed1999

Predicting children's sunscreen use: application of the theories of reasoned action and planned behavior.

BACKGROUND: Skin cancer remains the most common form of cancer in the United States despite the fact that most cases can be prevented by limiting sun exposure. Childhood and adolescence are periods of life during which prolonged sun exposure is particularly common. Accordingly, promoting sun-protective behaviors during these formative years can be of critical importance in preventing skin cancer. The present study applied the theories of reasoned action and planned behavior to the understanding of children's sunscreen use. Based on these theories, it was hypothesized that attitudes, subjective norms, and perceived behavioral control would be related to intentions to use sunscreen, which, in turn, would be related to actual sunscreen use. METHODS: Questionnaires measuring sun-related attitudes, beliefs, perceived control, and intentions were administered to 199 fourth graders (ages 9 to 13, mean = 10.3) attending public schools in Florida. Self-report measures of sun-related behavior were administered to the same subjects 1 month later. RESULTS: Results of correlational analyses were consistent with study hypotheses. Higher rates of sunscreen use at follow-up were predicted by stronger intentions to use sunscreen assessed 1 month previously. In addition, stronger intentions to use sunscreen were found to be related to more favorable attitudes toward sunscreen use, stronger beliefs that peers and parents favored sunscreen use, and greater perceptions of personal control in using sunscreen. Path and multiple regression analyses identified direct and indirect relationships among study variables that partially confirmed those predicted by the theories and provided support for the use of an expanded model that included perceived behavioral control. CONCLUSIONS: The present study confirmed hypotheses derived from the theories of reasoned action and planned behavior regarding the relation of attitudes, subjective norms, and perceived behavioral control to sunscreen use among fourth graders. In addition to their theoretical significance, these findings suggest ways to intervene at the individual, classroom, and family levels to promote greater sunscreen use in this age group.

Adolescent↗
PubMed1999

Treatment of root perforation by intentional reimplantation: a case report.

Intentional reimplantation is defined as a procedure in which an intentional tooth extraction is performed followed by reinsertion of the extracted tooth into its own alveolus. In this paper, intentional reimplantation is described and discussed as a treatment approach to root canal instrument separation in conjunction with root perforation. An 8-year follow-up case report is presented. The reimplanted tooth is now a fixed bridge abutment. Although successful in this case, the intentional reimplantation procedure should be considered a treatment of last resort, that is, when another treatment option is not viable for the treatment of root perforation/instrument retrieval.

Adult↗
PubMed1998

Cloning and functional characterization of PACAP-specific receptors in zebrafish.

Two PACAP receptors were isolated from total zebrafish cDNA library prepared from 6-day old fish by a homology-based cloning strategy. The two zebrafish PACAP receptors have the same topology as the one found in other members of this class of seven membrane-spanning G-protein-coupled receptors. Each of the two zebrafish PACAP receptors shares about 70% sequence identity at the amino acid level with the human PACAP-type 1 receptor, and about 50% amino acid identity with PACAP/VIP R-1 and PACAP/VIP R-2 receptors. One of these zebrafish receptors contains the hop2 configuration found in the human and rat PACAP-type 1 receptors. On the basis of these structural characteristics the zebrafish PACAP receptors were classified as PACAP-type 1 and PACAP-type 2 receptors. In competitive binding experiments zebrafish PACAP-type 1 and PACAP-type 2 receptors showed similar binding specificity for zebrafish and human PACAP-38 and PACAP-27. Furthermore, the specificity of PACAP-type 1 and PACAP-type 2 receptors for zebrafish and human PACAPs is about 1,000-fold higher than for human VIP. These results demonstrate that zebrafish PACAP-type 1 receptor is a structural and pharmacological homolog of the mammalian PACAP-type 1 receptor. Additional pharmacological characterization is needed in order to classify the zebrafish PACAP-type 2 receptor.

Amino Acid Sequence↗
PubMed1998

Sequence and expression of glutamic acid decarboxylase isoforms in the developing zebrafish.

We describe the isolation two glutamic acid decarboxylase (GAD) cDNAs from zebrafish with over 84% identity to human GAD65 and GAD67. In situ hybridization studies revealed that both GAD65 and GAD67 were expressed in the early zebrafish embryo during the period of axonogenesis, suggesting a role for GABA prior to synapse formation. Both GAD genes were detected in the telencephalon, in the nucleus of the medial longitudinal fasciculus in the midbrain, and at the border regions of the rhombomeres in the rostral hindbrain. In the caudal hindbrain, only GAD67 was detected (in neurons with large-caliber axons). In the spinal cord, both GAD genes were detected in dorsal longitudinal neurons, commissural secondary ascending neurons, ventral longitudinal neurons, and Kolmer-Agduhr neurons. Immunohistochemistry for gamma-aminobutyric acid (GABA) revealed that GABA is produced at all sites of GAD expression, including the novel cells in the caudal hindbrain. These results are discussed in the context of the hindbrain circuitry that supports the escape response. We conclude that fish, like mammals, have two GAD genes. The zebrafish GAD65 and GAD67 are present in identified neurons in the forebrain, midbrain, hindbrain, and spinal cord, and they catalyze the production of GABA in the developing embryo.

Amino Acid Sequence↗
PubMed1998

Zebrafish TrkC1 and TrkC2 receptors define two different cell populations in the nervous system during the period of axonogenesis.

We identified previously five distinct trk genes in the zebrafish. The structures of two of these, TrkC1 and TrkC2, are most similar to mammalian TrkC. Detailed sequence comparisons reported here indicate that although the similarities to TrkC are greatest in those regions of the extracellular domain implicated in ligand binding, the two sequences also differ significantly in these regions. Whole-mount in situ hybridization experiments in the early embryo revealed full-length trkC1 but no trkC2 transcripts in the cranial ganglia and in a subset of Rohon-Beard neurons. At the same time, full-length trkC2 but no trkC1 transcripts were detected laterally in the spinal cord, in the caudal hindbrain, in reticulospinal neurons of rhombomeres 4, 5, and 6, and in the midbrain. Both types of transcripts were expressed in clusters of cells in the dorsal telencephalon and the nucleus of the tract of the postoptic commissure. These results suggest distinct functions of trkC1 and trkC2 in nervous system development. The expression patterns define two different neuronal populations in the zebrafish.

Amino Acid Sequence↗
PubMed1998

Measurement of fatigue in cancer patients: development and validation of the Fatigue Symptom Inventory.

Although fatigue is one of the most common and debilitating symptoms experienced by cancer patients, it has received little systematic attention. This situation is due in large part to the lack of adequate instruments to measure fatigue. The primary aim of this study was to validate a newly developed measure of fatigue for use with cancer patients: the Fatigue Symptom Inventory (FSI). This 13 item self-report measure was designed to measure the intensity and duration of fatigue and its impact on quality of life. The psychometric properties of the FSI were assessed in women undergoing treatment for breast cancer, women who had completed treatment for breast cancer and women with no history of cancer. A seven-item interference subscale was found to have good internal consistency, with alpha coefficients above 0.90 in all three groups. The complete FSI was found to have rather weak to moderate test-retest reliability among patients in active treatment and healthy comparison subjects assessed on three separate occasions. Convergent validity was demonstrated using comparisons with existing measures of fatigue. Construct validity was demonstrated using comparisons between and within groups as well as comparisons with measures of anxiety and depression. Overall, the FSI was established as a valid and reliable measure of fatigue in cancer patients and healthy individuals. Suggestions are made for the potential application of the measure in clinical research.

Adult↗