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S Collins

Publications and source records attributed to S Collins.

At least 163 records · Page 9Linked to original sources
PubMed1994

Strategies for studying mouse and human immune responses to human papillomavirus type 16.

Cytotoxic T lymphocytes (CTL) are an important protective mechanism in viral infection and can be effective against tumours. We have investigated the tumour-associated E6 and E7 genes of human papillomavirus type 16 as CTL targets. In H-2b mice we have defined epitopes in E6 and E7 which can readily generate CTL in vivo and we have shown that HLA-A2.1 transgenic mice can generate an HLA-A2.1-restricted response. We have been unable to reveal a primed CTL response in humans. These paradoxical findings imply that human papillomavirus may fail to stimulate a systemic CTL response and/or employ strategies for evading or down-regulating such a response.

Amino Acid Sequence↗
PubMed1994

Real time blood flow imaging by spiral scan phase velocity mapping.

The work describes the development of a novel sequence that uses rapid spiral k-space sampling, combined with phase velocity mapping, for real time flow velocity imaging. The performance of the technique is assessed on phantoms for both through-plane and in-plane flows. The flow measurements compared well with those measured using a bucket and stopwatch. One advantage of the technique is that flow related signal loss is minimal due to the early acquisition of the center of k-space data. Flow artifacts were observed for in-plane flow and these were understood with the aid of computer simulations. In vivo studies involved cine velocity mapping in normal volunteers; aortic blood flow waveforms acquired by spiral scanning in two cardiac cycles compared well with data from a conventional gradient-echo sequence. Potential applications of the method are demonstrated by studying the response of aortic flow to physical exercise and the real time monitoring of aortic flow during a valsalver maneuver.

Algorithms↗
PubMed1994

Carbon tetrachloride suppresses T-cell-dependent immune responses by induction of transforming growth factor-beta 1.

In vivo exposure of B6C3F1 mice to the hepatotoxic chlorinated hydrocarbon, CCl4, suppresses T-cell-dependent humoral immune responses to sRBC. In the present studies, separation-crossover-reconstitution experiments with spleen cell subpopulations isolated from vehicle and CCl4-treated mice (500 mg/kg/day for 7 days) indicate that T-cells are the primary immunologic cell-type altered following CCl4 exposure. Despite suppression of T-cell activity, Con A-activated spleen cell supernatants from CCl4-treated mice produced greater amounts of biologically active IL-2 than untreated spleen cells. Furthermore, Con A-induced upregulation of the p55 subunit of the IL-2 receptor was not altered in spleen cells from CCl4-treated mice. The mediator of immune suppression is a serum-borne factor induced 48 hr following a single exposure to CCl4. Sera isolated from mice treated with CCl4 for 7 days (500 mg/kg/day) or 48 hr following a single exposure (1000 mg/kg) were found to possess high concentrations of TGF-beta 1. Direct addition studies demonstrated that T-cell-dependent AFC responses are more sensitive to suppression by TGF-beta 1 than are T-cell-independent responses. Finally, incubation of sera from CCl4-treated mice with TGF-beta 1-neutralizing mAb reversed the immune suppression associated with this serum. These results demonstrate that CCl4-induced immune suppression is at least partially mediated by induction of TGF-beta 1.

Animals↗
PubMed1994

Multi-residue analysis for beta-agonists in urine and liver samples using mixed phase columns with determination by radioimmunoassay.

A method is described for the extraction of four beta-agonists, clenbuterol, salbutamol, mabuterol and terbutaline from bovine urine and liver samples using radioimmunoassay (RIA) as the method of determination. Following enzymic digestion of the liver samples using protease enzyme, the digest is centrifuged and the harvested supernatant is saturated with sodium chloride and adjusted to pH 11.0. An ethyl acetate-propan-2-ol mixture is used to extract the beta-agonists from the liver digest. The samples of urine and liver extracts are adjusted to pH 6.0 and applied to mixed phase (XtrackT) columns. The column is washed with water and methanol and the beta-agonists are eluted with methanol containing 2% ammonia. After evaporation of the eluting solvent and reconstitution in ethanol the beta-agonist residues are determined by RIA, with standard graphs prepared in residue-free sample extract. The procedure has been validated for clenbuterol, salbutamol, mabuterol and terbutaline. The mean recovery of the beta-agonists from urine and liver is > 75% and > 85%, respectively. The detection limit is 0.13 ng ml-1 and 0.46 ng g-1 of clenbuterol in urine and liver, respectively. The high recoveries attained for both types of beta-agonists are a result of an efficient liquid-liquid extraction step coupled with a selective mixed solid-phase extraction procedure.

Adrenergic beta-Agonists↗
PubMed1994

Haemothorax after attempted intercostal catheterisation.

A 30-year-old man with chronic abdominal pain was referred to the Pain Relief Unit after a course of unsuccessful diagnostic blocks and treatments. On admission, history, examination and clinical investigations were consistent with a large pleural effusion due to a recent attempt to catheterise the intercostal space. Pleural drainage confirmed the diagnosis of haemothorax. Percutaneous intercostal nerve blocks are usually considered as safe and simple and no-one to our knowledge has reported such a complication.

Abdominal Pain↗
PubMed1994

Impaired expression and functional activity of the beta 3- and beta 1-adrenergic receptors in adipose tissue of congenitally obese (C57BL/6J ob/ob) mice.

Adipocytes from genetically obese (ob/ob) mice display an impaired response to beta-adrenergic stimulation, but the molecular defects have not been unequivocally identified. The expression and functional activity of the beta 1-, beta 2-, and beta 3-adrenergic receptor (AR) subtypes in white and brown adipose tissue from genetically lean and obese (ob/ob) mice were compared. Three beta 3AR transcripts of 2.1, 2.6, and 3.5 kilobases were identified in adipose tissue from lean mice by Northern blotting. All three beta 3AR mRNA species were dramatically reduced (by approximately 300-fold) in 12-week-old obese mice compared to those in lean animals. beta 1AR mRNA levels were also reduced (by approximately 4-fold) in obese mice, whereas beta 2AR mRNA levels were not significantly changed. The functional consequences of these changes in beta 3AR and beta 1AR expression were assessed by measuring beta-agonist-stimulated adenylyl cyclase activity in adipocyte plasma membranes with subtype-selective beta-adrenergic agonists and antagonists. Dose-response curves with epinephrine from lean mice were best fit to a two-component model comprised of 23% high affinity (K(act) = 1.42 x 10(-7) M) and 77% low affinity (K(act) = 1.67 x 10(-5) M) components, corresponding to activation of beta 1AR and beta 2AR conjointly, and beta 3AR, respectively. The beta 1AR-selective antagonist CGP20712A reduced the high affinity component to about 10%, whereas the nonselective beta-antagonist propranolol eliminated the high affinity component. The beta 3AR-selective agonist BRL37344 stimulated adenylyl cyclase activity in lean membranes to a slightly lesser extent than epinephrine, but was more potent (73% high affinity component; K(act) = 3.61 x 10(-8) M). In obese mice, stimulation of adenylyl cyclase by all agonists was severely blunted and was best fit to a single class of sites. Studies with CGP20712A or the beta 2AR-selective antagonist ICI118,551 indicated that this residual response was predominantly beta 2AR in character. Expression of beta AR subtypes in both brown and white adipose tissue of weanling obese mice (4-5-weeks of age) was also affected, but to a lesser extent, consistent with the progressive severity of obesity with age. Together the reduction in expression of the beta 3AR and beta 1AR impairs the beta-agonist-stimulated adenylyl cyclase response over a broad concentration range by greatly lowering the maximum stimulation and shifting the adrenergic sensitivity at low concentrations from a mixed beta 1AR/beta 2AR response to predominantly beta 2AR.

Adenylyl Cyclases↗
PubMed1994

Surgical variables affecting postoperative swallowing efficiency in oral cancer patients: a pilot study.

This study examined the correlation between swallow function at 3 months postoperatively and surgical variables including volume resected, flap volume, ratio of flap volume to volume resected, percentage of oral tongue, tongue base, and anterior and lateral floor of mouth resected, and whether or not the mandible was preserved in 30 surgically treated oral cancer patients. Swallows of measured amounts of liquid and paste (pudding) materials were examined videofluoroscopically. Nine measures of swallow function were completed for each swallow. A factor analysis of all swallow variables was done for liquid and for paste consistencies to determine whether one measure was statistically representative of all swallow measures. This analysis indicated that oral pharyngeal swallow efficiency (OPSE) represented all measures for both liquid and paste consistencies. Then the correlation between OPSE and surgical variables was defined. Only percentage of oral tongue and percentage of tongue base resected were significantly negatively correlated with OPSE. That is, OPSE decreased for both liquid and paste as percentage of oral tongue or percentage of tongue base resected increased. Results are discussed in terms of diet choices and surgical management.

Deglutition↗
PubMed1994

The use of third-party information in forensic assessments: a two-state comparison.

There is virtually no research on the normative characteristics of forensic mental health assessment, despite the significant increase in conceptual and empirical attention devoted to such assessment within the last 10 years. The present study addressed this deficit by examining the use of third-party information, a crucial component of forensic mental health assessment, by forensic clinicians in two states: Florida (a total of 277 evaluations on the issues of competency to stand trial and sanity at the time of the offense) and Virginia (316 evaluations addressing the same legal issues). Evaluations in each state were performed in either a community or a hospital setting. Basic information about the offense, records of prior mental health evaluation or treatment, and specific statements by victims or witnesses were the variables examined comprising "third-party information" in this study. More than three fourths of all evaluations across states and settings incorporated this information. There was less consistency in the use of mental health records and victim/witness statements, with significant differences observed across settings and states. Results are discussed in light of potential influences of state, setting, and study methodology.

Expert Testimony↗
PubMed1994

Growing pains.

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Holistic Health↗
PubMed1994

Patient-oriented rehabilitation planning in a single visit: first-year review of the Quick Program.

Persons who are geographically remote or do not qualify for inpatient rehabilitation have limited access to an effective multidisciplinary rehabilitation team. We present an innovative evaluation tool called the Quick Program. This multidisciplinary outpatient assessment involves a previsit database, therapy and physiatrist evaluations, a team meeting, and a patient-family meeting in a one-half day visit. Patient demographics and details of recommendations for the first 41 referrals are described. An average of 2.27 referrals per patient were made to resources outside of the core team, suggesting that the team achieved transdisciplinary status. The number of medical interventions recommended to accomplish rehabilitation goals (mean 2.16 per patient) suggests that the physiatrist was an active participant, and that physician input is crucial to success. We conclude that comprehensive rehabilitation planning for patients who have limited access to multidisciplinary rehabilitation team can be accomplished in a single visit.

Adult↗
PubMed1993

Desperate for doctors.

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Health Services Accessibility↗
PubMed1993

PCR cloning of an orphan homeobox gene (PRH) preferentially expressed in myeloid and liver cells.

Homeobox genes are members of a family of transcription factors that regulate tissue development in many different organisms. We set out to identify homeobox genes that might play a role in hematopoiesis. Using degenerate oligonucleotide primers corresponding to conserved homeobox sequences in the polymerase chain reaction (PCR), we cloned from the HL60 promyelocytic cell line a homeobox gene we now designate PRH. We mapped this gene, which was not homologous to any of the previously described homeobox genes, to chromosome 10, a region outside of the known genomic homeobox clusters. Northern blot hybridization indicates that PRH is preferentially expressed in myeloid and liver cells. The structure, chromosomal location, and pattern of expression of PRH indicate that it represents an orphan homeobox gene that may regulate the lineage development of certain hematopoietic cells.

Amino Acid Sequence↗