Biomedical subjects

S L Robinson

Publications and source records attributed to S L Robinson.

At least 19 recordsLinked to original sources

PubMed2000

Development of a measure of workplace deviance.

The purpose of this research was to develop broad, theoretically derived measure(s) of deviant behavior in the workplace. Two scales were developed: a 12-item scale of organizational deviance (deviant behaviors directly harmful to the organization) and a 7-item scale of interpersonal deviance (deviant behaviors directly harmful to other individuals within the organization). These scales were found to have internal reliabilities of .81 and .78, respectively. Confirmatory factor analysis verified that a 2-factor structure had acceptable fit. Preliminary evidence of construct validity is also provided. The implications of this instrument for future empirical research on workplace deviance are discussed.

Adult↗

PubMed1999

Determining sources of fecal pollution in a rural Virginia watershed with antibiotic resistance patterns in fecal streptococci.

Nonpoint sources of pollution that contribute fecal bacteria to surface waters have proven difficult to identify. Knowledge of pollution sources could aid in restoration of the water quality, reduce the amounts of nutrients leaving watersheds, and reduce the danger of infectious disease resulting from exposure to contaminated waters. Patterns of antibiotic resistance in fecal streptococci were analyzed by discriminant and cluster analysis and used to identify sources of fecal pollution in a rural Virginia watershed. A database consisting of patterns from 7,058 fecal streptococcus isolates was first established from known human, livestock, and wildlife sources in Montgomery County, Va. Correct fecal streptococcus source identification averaged 87% for the entire database and ranged from 84% for deer isolates to 93% for human isolates. To field test the method and the database, a watershed improvement project (Page Brook) in Clarke County, Va., was initiated in 1996. Comparison of 892 known-source isolates from that watershed against the database resulted in an average correct classification rate of 88%. Combining all animal isolates increased correct classification rates to > or = 95% for separations between animal and human sources. Stream samples from three collection sites were highly contaminated, and fecal streptococci from these sites were classified as being predominantly from cattle (>78% of isolates), with small proportions from waterfowl, deer, and unidentified sources ( approximately 7% each). Based on these results, cattle access to the stream was restricted by installation of fencing and in-pasture watering stations. Fecal coliforms were reduced at the three sites by an average of 94%, from prefencing average populations of 15,900 per 100 ml to postfencing average populations of 960 per 100 ml. After fencing, <45% of fecal streptococcus isolates were classified as being from cattle. These results demonstrate that antibiotic resistance profiles in fecal streptococci can be used to reliably determine sources of fecal pollution, and water quality improvements can occur when efforts to address the identified sources are made.

Animals↗

PubMed1998

Isolation and characterization of fluorophore-binding RNA aptamers.

BACKGROUND: In vitro selection has been shown previously to be a powerful method for isolating nucleic acids with specific ligand-binding functions ('aptamers'). Given this capacity, we have sought to isolate RNA motifs that can confer fluorescent labeling to tagged RNA transcripts, potentially allowing in vivo detection and in vitro spectroscopic analysis of RNAs. RESULTS: Two aptamers that recognize the fluorophore sulforhodamine B were isolated by the in vitro selection process. An unusually large motif of approximately 60 nucleotides is responsible for binding in one RNA (SRB-2). This motif consists of a three-way helical junction with two large, highly conserved unpaired regions. Phosphorothioate mapping with an iodoacetamide-tagged form of the ligand shows that these two regions make close contacts with the fluorophore, suggesting that the two loops combine to form separate halves of a binding pocket. The aptamer binds the fluorophore with high affinity, recognizing both the planar aromatic ring system and a negatively charged sulfonate, a rare example of anion recognition by RNA. An aptamer (FB-1) that specifically binds fluorescein has also been isolated by mutagenesis of a sulforhodamine aptamer followed by re-selection. In a simple in vitro test, SRB-2 and FB-1 have been shown to discriminate between sulforhodamine and fluorescein, specifically localizing each fluorophore to beads tagged with the corresponding aptamer. CONCLUSIONS: In addition to serving as a model system for understanding the basis of RNA folding and function, these experiments demonstrate potential applications for the aptamers in transcript double labeling or fluorescence resonance energy transfer studies.

Animals↗

PubMed1998

An Australian isolate of Mycobacterium shimoidei.

A case of Mycobacterium shimoidei in a 75 year old man is reported. He had been a smoker, with a past history of bullous emphysema and a lung abscess. He had a 12 month history of weight loss, night sweats, with increased cough and sputum, and progressive opacification of the left apex with cavity formation. Sputum repeatedly grew M. shimoidei, identification of which was confirmed with high-pressure liquid chromatography (HPLC). He was treated for 45 days with three drugs to which the organism was sensitive, but failed to respond. His death was attributed to mycobacterial infection.

Aged↗

PubMed1996

Effects of the calcium channel blocker nimodipine on nicotine-induced locomotion in rats.

The effects of nimodipine, an L-type calcium channel antagonist, on nicotine-induced locomotor activity were investigated in drug-naive rats. Nicotine (0.4 mg/kg i.p.) produced significant increases in locomotion following acute administration. However, when rats were given injections of nimodipine (5, 10, or 20 mg/kg i.p.) 1 h prior to the test drug, nicotine-induced locomotor activity was altered. Nimodipine 5 mg did not significantly block locomotor activity produced by nicotine. In contrast, pretreatment with 10 and 20 mg nimodipine significantly blocked nicotine-induced locomotor activity. These findings clearly indicate that nicotine-induced locomotion is altered by nimodipine in a dose-dependent fashion. Results further suggest that the effect of nicotine on locomotion is calcium-dependent.

Animals↗

PubMed1996

Genetic diversity among selected ethnic subpopulations of Australia: evidence from three highly polymorphic DNA loci.

Immigration has been the principal source of population growth in Australia since European settlement began in 1788. As a result, the Australian gene pool has been constantly evolving, particularly over the last 50 years, during which peoples from many European and Asian countries have arrived in large numbers. Three highly polymorphic DNA loci (D1S80, HLA-DQA1, and human THO1) are used to assess the level of diversity among six immigrant subpopulations that compose significant elements in present-day Australia, namely, Asians, Italians, Greeks, Slavs, Middle Easterners, and a "general white" sample. Asian migrants are the most distinctive of the groups at all three loci, possessing the highest frequencies of alleles HLA-DQA1*3 and D1S80*27, *28, and *30, and an exceptionally high frequency of THO1*9. The European-derived groups cluster together separately from Asians, but Greeks are characterized by their frequencies of HLA-DQA1*2 and *4 and THO1*8. Middle Easterners lie on the fringe of the European cluster. When the results of the present study are combined with worldwide data for each of the three DNA markers, these hypervariable loci, especially D1S80 and THO1, are able to differentiate the major groups of humans. The level of population differentiation revealed by RST values for the three DNA markers is similar to or even less than the values recorded for the less polymorphic classical genetic markers. Therefore these three DNA markers are highly suitable for both forensic purposes and the investigation of population relationships.

Adult↗

PubMed1996

HUMTH01 validation studies: effect of substrate, environment, and mixtures.

New DNA typing methods need to be thoroughly validated prior to use in forensic investigation. This includes determining the effects different sample conditions have on the typeability of those samples. Biological samples routinely encountered in forensic case work were exposed to a series of different substrates, environmental conditions, and mixtures and typed for the STR HUMTH01 using PCR. None of the conditions resulted in a false typing or preferential allele amplification. It is demonstrated that the application of HUMTH01 typing methods in forensic case work can be reliable, robust, and efficient.

Blood Stains↗

PubMed1995

Mannose binding protein (MBP) enhances mononuclear phagocyte function via a receptor that contains the 126,000 M(r) component of the C1q receptor.

Mannose-binding protein (MBP), C1q, the recognition component of the classical complement pathway, and pulmonary surfactant protein A (SP-A) are members of a family of molecules containing a collagen-like sequence contiguous with a noncollagen-like sequence, and usually having the properties of a lectin. C1q and SP-A have been shown to enhance monocyte FcR- and CR1-mediated phagocytosis, suggesting that the common structural features of the collagen-like domains may provide a basis for this immunologically important function. Results presented here demonstrate that MBP also enhanced FcR-mediated phagocytosis by both monocytes and macrophages, and stimulated CR1-mediated phagocytosis in human culture-derived macrophages and in phorbol ester-activated monocytes. Furthermore, a monoclonal antibody that recognizes a 126,000 M(r) cell surface protein and inhibits C1q-enhanced phagocytosis, inhibited the MBP-mediated enhancement of phagocytosis. Thus, the receptors that mediate the enhancement of phagocytosis by MBP and C1q share at least one critical functional component, the 126,000 M(r) ClqRP.

Carrier Proteins↗

PubMed1995

Localization and regulation of the human very low density lipoprotein/apolipoprotein-E receptor: trophoblast expression predicts a role for the receptor in placental lipid transport.

The very low density lipoprotein/apolipoprotein-E receptor (VLDLR) is the newest member of the low density lipoprotein receptor (LDLR) family. Very little is known about VLDLR localization and regulation. Immunohistochemical analysis of human placenta with a specific polyclonal antibody detected VLDLR in syncytiotrophoblast and intermediate trophoblast cells. VLDLR transcripts were also localized in these cells by in situ hybridization histochemistry. In addition, VLDLR messenger RNA (mRNA) was detected in villous core endothelial cells and cells appearing to be Hofbauer cells. Northern blot analysis of placenta revealed a 2.6-fold increase in VLDLR mRNA at term compared to that in the first trimester. The regulation of VLDLR expression was studied in JEG-3 and BeWo choriocarcinoma cells, two trophoblast-derived cell lines. Treatment of these cells with 8-bromo-cAMP caused a profound suppression of VLDLR message, whereas LDLR transcripts were increased. Incubation of JEG-3 cells with 25-hydroxycholesterol did not lead to sterol negative feedback on VLDLR gene expression, unlike LDLR mRNA, which declined markedly. Insulin (200 mg/L) up-regulated VLDLR message in JEG-3 cells 2-fold, as did the fibrate hypolipidemic drug, clofibric acid. We conclude that 1) VLDLR is expressed in human placental trophoblast cells in a pattern consistent with a role in placental lipid transport; 2) VLDLR expression is high at term relative to that in the first trimester; and 3) the trophoblast VLDLR is subject to down-regulation by cAMP and up-regulation by insulin and fibrate hypolipidemic drugs.

Apolipoproteins↗

PubMed1994

Cell-surface protein identified on phagocytic cells modulates the C1q-mediated enhancement of phagocytosis.

C1q, a subunit of the first component of the classical C pathway, binds to specific cells of the immune system, triggering a variety of cellular responses. To identify the functional C1qR on phagocytic cells, mAbs were generated by immunization with either C1q-binding proteins isolated from U937 cells or intact U937 cells. Immunoprecipitation followed by Western blot analysis demonstrated that three mAbs, designated R139 (IgG2b), R3 (IgM), and U40.3 (IgG1), recognize the same 100,000 M(r) protein (126,000 M(r) under reducing conditions). These mAbs also co-immunoprecipitate CD43 from detergent extracts of U937, consistent with the possibility that this C1qR is a multi-subunit structure. Two Abs, R3 and R139, but not U40.3, consistently inhibited the enhancement of phagocytosis by monocytes adhered to either C1q or the collagen-like fragment of C1q (C1q-CLF). Interestingly, binding inhibition studies demonstrated that neither R139 nor U40.3 blocked the binding of [125I]C1q-CLF to U937 cells, whereas R3 did inhibit 35 to 45% of the binding of [125I]C1q-CLF to these cells. Thus, the three mAbs recognize distinct epitopes of a 100,000 M(r) polypeptide that is a component of the monocyte C1qR that modulates phagocytosis. All three mAbs recognize the extracellular domain of the molecule on neutrophils, monocytes, and U937 cells, but were not reactive with CEM or RAJI cells, T and B lymphoblastoid cell lines, respectively. Furthermore, none of these three mAbs inhibited or mimicked the C1q-mediated stimulation of superoxide production by neutrophils, suggesting that the C1qR that mediates the enhancement of phagocytosis differs in at least some critical parameter from the C1qR that mediates superoxide generation by the neutrophil.

Antibodies, Monoclonal↗

PubMed1994

HUMTH01: amplification, species specificity, population genetics and forensic applications.

Length variation at the short tandem repeat (STR) locus HUMTH01 can be reliably detected from small amounts of DNA (0.01-10 ng) extracted from a range of forensic human samples, using the polymerase chain reaction (PCR), horizontal polyacrylamide gels and silver staining. It was shown that the oligonucleotide primers used are specific to humans and some higher primates. Population data bases of Caucasians and Asians living in Victoria (Australia) were constructed and the differences in allele frequencies between Caucasians and Asians confirmed. A new allele provisionally designated HUMTH01*12 was identified. The discrimination power provided by this locus (0.86-0.91) has been used effectively in a range of forensic case studies.

Alleles↗

PubMed1993

Salivary testosterone in children with and without learning disabilities.

Previous studies have indicated that the sex steroids have organizational effects upon neural tissue and that abnormal secretion during development may lead to functional anomalies. In this study, we explore the possibility of prepubertal steroid hormone involvement in the etiology of learning disabilities. Salivary testosterone levels in 264 children without learning disabilities (133 males, 131 females) were measured and compared to that in 32 children with learning disabilities (25 males, 7 females). The presence of learning disabilities was significantly associated with higher salivary testosterone. Data from equivalent samples of learning-disabled and control subjects also were compared separately because of disparities in sample size and variable distribution in the total group analysis. A 32-member sample of nonlearning-disabled children was created by randomly selecting individuals who exactly matched the age, race, and sex characteristics of the learning-disabled group. The matched analysis further substantiated the association between testosterone secretion and learning disabilities. Thus, it is possible that some learning disabilities may be associated in part with abnormal testosterone levels.

Adolescent↗

PubMed1993

Splanchnic mucosal perfusion effects of hypertonic versus isotonic resuscitation of hemorrhagic shock.

A porcine hemorrhagic shock (HS) model was used to assess the splanchnic mucosal and systemic effects of hypertonic versus isotonic crystalloid resuscitation. Animals were bled to a mean arterial pressure of 40 mm Hg for 1 hour and then resuscitated with equivalent sodium loads of LR, 7.5 per cent hypertonic saline (HSS), or 7.5 per cent HSS with 6 per cent Dextran (HSD). Intestinal mucosal blood flow (IMBF) was measured by a laser Doppler flow probe placed on the mucosa of the small bowel. Following resuscitation the cardiac output (CO) (relative to baseline values) was significantly higher with HSD (158 17 per cent) and HSS (137 24 per cent) than with LR (84 27 per cent) (P < 0.005). There was prompt restoration of IMBF with both HSD (126 31 per cent) and HSS (106 22 per cent) (vs baseline). Resuscitation with LR was associated with a persistent reduction in IMBF (52 16 per cent) despite restoration of mean arterial pressure and cardiac output to baseline levels (P < 0.05). Thus, hypertonic saline solutions may serve an adjunctive role in the resuscitation of hemorrhagic shock by restoring intestinal nutrient blood flow and, thereby, preventing gut barrier impairment, bacterial translocation, and organ failure.

Animals↗

PubMed1992

Cardiovascular and plasma catecholamine responses at tracheal extubation.

The haemodynamic responses to tracheal extubation at the end of surgery were compared with those occurring at tracheal intubation in 12 patients undergoing major elective surgery. Arterial cannulation was performed and heart rate (HR), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) were measured before induction of anaesthesia, before tracheal intubation, at the end of surgery and 1, 3 and 5 min after tracheal extubation. Laryngoscopy was avoided at the end of surgery. At all but the first of these stages, venous blood was obtained for measurement of plasma concentrations of adrenaline and noradrenaline. Rate-pressure product (RPP) was derived from SAP x HR. After tracheal intubation there were significant (P less than 0.05) increases in HR, DAP, RPP and in plasma concentrations of both adrenaline and noradrenaline. After extubation, only HR and adrenaline concentration at 5 min after extubation increased significantly compared with measurements at the end of surgery.

Adult↗

PubMed1992

Electronic and disposable patient-controlled analgesia systems. A comparison of the Graseby and Baxter systems after major gynaecological surgery.

We have compared the performance of the Baxter disposable with the Graseby electronic patient-controlled analgesia system in 30 patients following major gynaecological surgery. Patients were allocated randomly to receive analgesia via the Baxter or Graseby device for postoperative pain relief. There were no significant differences between the two groups with regard to postoperative pain relief or sedation as measured by visual analogue scale. Requirements for antiemetic drugs and patient acceptability were similar. Mean (SEM) morphine demanded over 30 h was 35.7 (6.6) in the Graseby group and 35.1 (8.5) in the Baxter group.

Adult↗

PubMed1992

Cardiovascular responses to insertion of the laryngeal mask.

We have compared, in 40 healthy patients, the cardiovascular responses induced by laryngoscopy and intubation with those produced by insertion of a laryngeal mask. Anaesthesia was induced with thiopentone and maintained with enflurane and nitrous oxide in oxygen; vecuronium was used for muscle relaxation. Arterial pressure was measured with a Finapres monitor. The mean maximum increase in systolic arterial pressure after laryngoscopy and tracheal intubation was 51.3% compared with 22.9% for laryngeal mask insertion (p less than 0.01). Increases in maximum heart rate were similar, (26.6% v 25.7%) although heart rate remained elevated for longer after tracheal intubation. We conclude that insertion of the laryngeal mask airway is accompanied by smaller cardiovascular responses than those after laryngoscopy and intubation and that its use may be indicated in those patients in whom a marked pressor response would be deleterious.

Adult↗

PubMed1992

Splenic abscess associated with endocarditis.

BACKGROUND: Refractory or recurrent sepsis in patients with endocarditis may be from splenic abscess. The purpose of this review is to assess this relationship. METHODS: Of 564 patients treated for documented endocarditis between 1970 and 1990, splenic abscesses developed in 27 patients. The mean age of the 18 men and nine women was 37 years. Etiologic factors included street drugs, dental abscess, and rheumatic fever. Symptoms included fever, myalgia, chills, and dyspnea; the prodrome averaged 2 weeks. Typical signs were heart murmur, left lower-lobe infiltrate, and leukocytosis. Splenomegaly was found in three patients. All patients had valve lesions, which involved the aortic valve alone in 10 patients, the mitral valve alone in eight patients, and multiple valves in nine patients. RESULTS: A splenic defect on computed axial tomographic scan was diagnosed correctly as an abscess in 10 patients, was indeterminant in three patients, and was incorrectly called an infarct in four patients. Thirteen patients died. All 10 patients treated without splenectomy died, including five patients who underwent valvular replacement. In contrast, only three of 17 patients treated by splenectomy with (11 patients) or without (six patients) valvular surgery died. CONCLUSIONS: Splenic abscess often accompanies endocarditis. The diagnosis is suspected by refractory fever and confirmed by abdominal computed axial tomography scan. Splenectomy is warranted before or after valvular surgery, depending on the patient's clinical response to antibiotics.

Abscess↗

PubMed1991

Phagocytic cell molecules that bind the collagen-like region of C1q. Involvement in the C1q-mediated enhancement of phagocytosis.

C1q binds to and elicits cellular responses by several cell types, including monocytes, macrophages, neutrophils, B cells, and fibroblasts. The cell-binding domain is located within the collagen-like pepsin-resistant region of the C1q molecule (C1q tails). An affinity matrix of C1q tails coupled to Sepharose was used to select C1q-binding proteins from detergent extracts of surface-iodinated human monocytes, polymorphonuclear leukocytes, and the U937 cells. The major radiolabeled polypeptide eluted specifically from the ligand affinity column had an apparent molecular mass (Mr) of 126,000. Minor iodinated components eluted from Sepharose-tails migrated with Mr of 216,000 and 55,000. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions no change in the migration of any of these polypeptide bands was detected. None of these polypeptides reacted with antibodies directed against the integrins alpha 5 beta 1 (fibronectin receptor) or alpha v beta 3 (vitronectin receptor), LFA-1, or to several other cell adhesion molecules. The Mr 126,000 band was found to contain more than one polypeptide. Lectin binding properties, susceptibility to glycosidases and proteases, and immunoreactivity with the monoclonal antibody L-10, indicated that CD43 (sialophorin/leukosialin) is a component of this band. However, further data show that a monoclonal antibody, generated by immunization with the isolated Clq-binding fractions, recognizes a cell surface sialoglycoprotein distinct from CD43 and inhibits the C1q-mediated enhancement of phagocytosis in monocytes. These latter observations provide the first definitive connection between a specific phagocytic cell surface protein and a known C1q-mediated function. While these proteins contain sialic acid, binding assays and functional assays using neuraminidase-treated cells demonstrate that the functional interaction between C1q and the cell surface is not via sialic acid. The data taken together indicate either that the functional C1q receptor on phagocytic cells is a multi-subunit complex or that multiple proteins can interact with the fragment of C1q containing the cell-binding domain, at least one of which is involved in the C1q-mediated enhancement of phagocytosis.

Amino Acid Sequence↗