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Biomedical subjects

C Sampson

Publications and source records attributed to C Sampson.

At least 19 recordsLinked to original sources
PubMed2005

Coronary artery bypass graft imaging using ECG-gated multislice computed tomography: comparison with catheter angiography.

AIM: To compare the value of multislice computerized tomography (MSCT) in imaging coronary artery bypass grafts (CABGs) by direct quantitative comparison with standard invasive angiography. METHODS: Using MSCT, 50 consecutive patients who had previously undergone CABG surgery and had recently undergone invasive angiography for recurrent angina pectoris, were studied further using MSCT after intravenous injection of non-ionic contrast agent; cardiac imaging was performed during a single breath-hold. Graft anatomy was quantified, using both quantitative coronary angiography (QCA) and MSCT, by different investigators blinded to each other. Reproducibility was quantified using the standard error of the measurement expressed as a percentage in log-transformed values (CV%) and intraclass correlation (ICC). RESULTS: All 150 grafts were imaged using MSCT; only 4 patent grafts were not imaged using selective angiography. Good agreement was achieved between MSCT and QCA on assessment of proximal anastomoses (CV% 25.2, ICC 0.84), mid-vessel luminal diameter (CV% 15.5, ICC 0.91) and aneurysmal dilations (CV% 14.3). Reasonable agreement was reached on assessment of distal anastomoses (CV% 26.7, ICC 0.66) and categorization of distal run-off (ICC 0.73). Good agreement was observed for stenoses of over 50% luminal loss (CV% 8.7, ICC 0.97) but agreement on assessment of less severe lesions was poor (CV% 208.7, ICC 0.51). CONCLUSION: This study demonstrates that CABGs can be quantitatively evaluated using MSCT, and that significant lesions present in all CABG segments can be reliably identified. Agreement between MSCT and QCA for lesions of less than 50% luminal loss was poor.

Aged↗
PubMed2003

Maternal diabetes mellitus is associated with altered deposition of fibrin-type fibrinoid at the villous surface in term placentae.

Placentae from control and diabetic patients were used to test three null hypothesis: (1) there are no significant group differences in the volumes of villous syncytiotrophoblast compartments or intervillous fibrin-type fibrinoid, (2) perivillous fibrin-type fibrinoid is deposited randomly at the surface of trophoblast, and (3) amounts and deposition patterns of perivillous fibrin-type fibrinoid do not vary between groups. Term placentae were collected from non-diabetic subjects and five groups of diabetic women classified according to duration, severity and insulin dependence. Tissue specimens and sections were obtained by uniform random sampling. Volumes and surface areas of fibrin-type fibrinoid and trophoblast compartments (thin, syncytial knot, syncytial bridge and denuded regions) were estimated stereologically and compared using variance, chi-squared and contingency table analyses. As to null hypothesis (1), no group differences in volumes of trophoblast compartments were found but volumes of intervillous fibrin-type fibrinoid were greater in the non-insulin-dependent diabetic group. As to null hypothesis (2), regardless of group, fibrin-type fibrinoid was deposited preferentially at sites of denudation in every placenta examined. As to null hypothesis (3), villous surface areas occupied by perivillous fibrin-type fibrinoid were greater in type 1 (insulin-dependent) diabetics with complications (diabetic nephropathy or retinopathy). The surfaces of trophoblast occupied by fibrin-type fibrinoid were also notably larger in non-insulin-dependent diabetics and type 1 diabetics with complications. Except for the surface of denudation sites (which also increased in diabetes), there were no differences in the surfaces of trophoblast regions. These results confirm that the haemostatic steady state is perturbed in the diabetic placenta, that perivillous fibrin-type fibrinoid is deposited preferentially at sites of epithelial loss/damage, and that some diabetic groups are affected differentially.

Adult↗
PubMed2001

Cloning and characterization of cDNAs encoding four different canine immunoglobulin gamma chains.

cDNAs encoding four different canine immunoglobulin G (caIgG) gamma chains were identified in this study. One of these IgG gamma chain cDNAs, (caIgG-A), represents 92.5% of the IgG gamma chain cDNAs in a dog spleen cell cDNA library; a second partial IgG gamma chain cDNA (caIgG-B) was also identified in the library. The other two IgG gamma chain cDNAs (caIgG-C and caIgG-D) were RT-PCR amplified from canine lymphoma samples. Comparison of the four different canine IgG gamma chain cDNAs showed homologies from 83.6 to 89.2% and from 73.1 to 81.8% at nucleotide and amino acid sequence levels, respectively. Despite the high similarity in CH1, CH2 and CH3 domains among the different caIgG gamma chains, the hinge regions were distinct, sharing only 19.0-35.2% homology at the amino acid level. No multiple duplication of the hinge region, as reported for human IgG1 and IgG3, was detected in any of the canine IgG gamma chains. The numbers of cysteines in the putative hinge regions were found to be 3, 2, 7 and 3 for the four canine IgG heavy gamma chains (A, B, C and D), respectively. Specific primers were designed based on caIgG gamma chain hinge region DNA sequences and were used in RT-PCR for measuring different caIgG gamma chain mRNA levels in canine PBMC samples.

Amino Acid Sequence↗
PubMed2001

Transforming growth factor-beta has contrasting effects in the presence or absence of exogenous interleukin-12 on the in vitro activation of cells that transfer experimental autoimmune thyroiditis.

Mouse thyroglobulin (MuTg)-sensitized spleen cells activated in vitro with MuTg induce experimental autoimmune thyroiditis (EAT) in recipient mice with a thyroid infiltrate consisting primarily of lymphocytes. A more severe and histologically distinct granulomatous form of EAT (G-EAT) is induced when donor cells are activated with MuTg together with anti-interferon-gamma (IFN-gamma), anti-interleukin-2 receptor (IL-2R) monoclonal antibody (mAb), and IL-12. Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine that can both suppress and exacerbate autoimmune diseases and often has inhibitory effects on lymphocytes. To determine if TGF-beta could modulate the in vitro activation of effector cells for G-EAT, TGF-beta was added to cultures of MuTg-sensitized donor spleen cells together with MuTg. Cells activated in the presence of 2 ng/ml TGF-beta induced moderately severe G-EAT in recipient mice. G-EAT induced by cells activated in the presence of TGF-beta was histologically similar but less severe than the G-EAT induced by cells activated in the presence of IL-12. IL-12 and TGF-beta modulate the activation of G-EAT effector cells by distinct mechanisms, as cells activated by TGF-beta could induce G-EAT in the presence of anti-IL-12, and TGF-beta inhibited the effects of IL-12 on EAT effector cells. TGF-beta exerted its activity during the first 24 h of the 72-h culture, whereas IL-12 functioned primarily during the final 24 h of culture. These results indicate that thyroid lesions with granulomatous histopathology can be induced by both IL-12-dependent and IL-12-independent mechanisms, and TGF-beta can exert both positive and negative effects on the effector cells for G-EAT.

Adoptive Transfer↗
PubMed1996

Intramural hematoma of the aorta caused by a penetrating atheromatous ulcer.

Aortic dissection is a life-threatening condition which is difficult to diagnose because of its variable clinical presentation and diverse pathophysiologic manifestations. We present a case in which intramural hematoma of the thoracic aorta occurred in the absence of an intimal flap. Computed tomography and magnetic resonance imaging both showed hemorrhage in the wall of the aorta. Transesophageal echocardiography also revealed a penetrating atherosclerotic ulcer in the transverse aorta as a cause of the hematoma. A high index of clinical suspicion and a combination of diagnostic procedures resulted in proper diagnosis and successful surgical treatment.

Aged↗
PubMed1995

Magnetic resonance acquisition to determine the lumen length of a tortuous phantom aorta.

PURPOSE: Endovascular abdominal aortic aneurysm repair is a technique that requires an accurate measurement of the aneurysm's lumen length prior to the procedure. This study examines the accuracy of luminal length measurement in an aortic phantom using magnetic resonance angiography (MRA) axial source images. METHODS AND RESULTS: Tortuous phantom aortas were constructed using water-filled plastic tubing (7 mm in diameter with lengths of 80 to 160 mm). The tubes were molded into three-dimensional "S" or "C" shapes that simulated the luminal course of a tortuous aorta. Phantoms were imaged at angles of 0 degrees, 15 degrees, 30 degrees, and 45 degrees to the image slice direction on a 1.5T Signa MR scanner using a transaxial two-dimensional time-of-flight (TOF) and a T1-weighted spin-echo acquisition. The luminal length of the phantom was calculated after establishing the lumen center coordinates in axial source images and then measuring the distance between two sequential slices using the Pythagorean theorem. The accuracy of this measurement in the phantom was 89% to 99.6%, proportional to the length of the tubing. Accuracy was not affected by angulation of < 45 degrees. CONCLUSION: Two-dimensional TOF MRA source images can provide an accurate measurement of the phantom aorta's lumen length.

Aorta↗
PubMed1994

Acquired arteriovenous fistulas in children.

Five boys with acquired arteriovenous fistulas are presented; four had factor VIII deficiencies, and one had a hepatic-induced coagulopathy. The cause of the fistula was the trauma induced by single or repeated venous and/or arterial punctures. All five developed a slowly progressive pulsatile mass of over a period of months. Patients with coagulopathies all developed complications with repeated inadvertent puncture of these masses. Clinical examination and magnetic resonance imaging scans clearly highlight this problem. Surgical ligation is recommended for progressive enlargement.

Arteriovenous Fistula↗
PubMed1994

Venoatrial pathways after the Mustard operation for transposition of the great arteries: anatomic and functional MR imaging.

PURPOSE: To evaluate spin-echo (SE) and cine gradient-echo (GRE) magnetic resonance (MR) imaging with velocity mapping for detecting late complications of the Mustard operation. MATERIALS AND METHODS: Twenty-one patients were studied with MR imaging 1-22 years after undergoing the Mustard operation. Twenty were also studied with transthoracic echocardiography, 18 with angiocardiography, and five with transesophageal echocardiography. RESULTS: MR imaging showed no venoatrial obstruction in nine patients. This result was confirmed with angiocardiography in seven cases and postmortem examination in one case. In one case, MR imaging demonstrated a leak at the baffle suture line. Of 12 cases with venoatrial obstruction at MR imaging, nine were confirmed with angiocardiography or surgery. There were two false-positive MR studies and one case in which no conclusion was reached. CONCLUSION: With addition of cine GRE sequences and velocity mapping to SE sequences, MR imaging is a useful noninvasive method of investigating late complications of the Mustard operation.

Adult↗
PubMed1994

Relationship of APP mRNA transcripts and levels of NGF and low-affinity NGF receptors to behavioral measures of age-related cognitive dysfunction.

This study was designed to examine the relationship between cognitive function and endogenous levels of NGF, low-affinity NGF receptor (LNGFR), and amyloid precursor protein (APP) mRNAs. Using 3 month (n = 5), 18 month (n = 40), and 29 month (n = 17) Fischer-344 male rats, cognitive function was assessed with the Morris water maze, reverse transcription and polymerase chain reaction were used to quantify APP mRNAs, and NGF and LNGFR levels were determined with an ELISA. Cognitive function declined progressively with age from 3 months to 18 months, and from 18 months to 29 months, but only RNA content in the tissue declined significantly from 3 months to 18 months. Between 18 month and 29 month rats were small but statistically significant decreases only for Kunitz protease inhibitor (KPI)-inclusive mRNAs and cortical NGF levels. There was a small but statistically significant correlation between cognitive function and %KPI (the amount of KPI APP mRNAs relative to the total amount of APP mRNA), with lower %KPI related to more impaired spatial learning. No other statistically significant correlation or linear relationship could be detected between cognitive function and any of the other neurological measures or any combination of these measures (i.e., hippocampal levels of APP 695 mRNA, cortical and hippocampal levels of NGF, and cortical, hippocampal, and basal forebrain levels of LNGFR).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1993

Leprosy in women: characteristics and repercussions.

"Health is often measured in terms of low mortality; nevertheless, merely being alive is not a measure of the quality of life" H. Méndez Castellanos. Physiological, socioeconomic and cultural factors play important roles in the response of women to Mycobacterium leprae and in the impact of leprosy on their lives. They appear to develop stronger immunological responses to M. leprae than men, as suggested by lower incidence and less severe clinical forms of disease in most areas of the world, as well as stronger reactions of cell-mediated immunity after prophylactic vaccination. Genetic factors and physiological status including pregnancy, intercurrent infection and malnutrition might be among the factors which modulate this response. Women in leprosy-endemic areas of the world, with few exceptions, suffer from marked economic and social dependency and inferiority which can only be heightened by the social stigma associated with leprosy. Nevertheless, they bear an enormous responsibility for the health of their families, often as head of the household, and they often possess a unique capacity to influence community opinion. With the introduction of multidrug therapy, leprosy control throughout the world is no longer an unrealistic goal. Active vaccination may constitute the other factor necessary for eventual eradication of the disease. The incorporation of women at all levels into active roles in health care programs may constitute one of the decisive factors in the success or failure of leprosy control.

Adolescent↗
PubMed1993

Comparison of the promoter region of the human and porcine choline acetyltransferase genes: localization of an important enhancer region.

Genomic clones of human and porcine choline acetyltransferase were obtained by screening genomic libraries with synthetic oligonucleotides. The human and porcine genes exhibit significant conservation of both their intron/exon structure and the nucleotide sequence in their 5' flanking regions. However, the two genes differ in several respects, including the absence of a "TATA" box in the human gene and differences in the position of the methionine start codon. Analysis of the promoter region of the two genes has led to the localization of an enhancer element that appears necessary for efficient transcription of the gene.

Animals↗
PubMed1993

BCG vaccination protects against leprosy in Venezuela: a case-control study.

A total of 64,570 household and other close contacts of about 2000 leprosy cases were screened for eligibility for entry into a trial of a new leprosy vaccine. The screening procedure included a clinical examination for leprosy and for the presence of BCG and lepromin scars. Ninety-five new cases of leprosy were identified, and the prevalence of BCG and lepromin scars among them was compared with similar data from matched controls selected from among those with no evidence of leprosy. The difference in the prevalence of BCG scars in the two groups was used to estimate the protection against leprosy conferred by BCG vaccination. One or more BCG scars was associated with a protective efficacy of 56% (95% confidence limits 27% to 74%). There was a trend of increasing protection with four or more BCG scars, but this was not statistically significant. There was no evidence that the efficacy of BCG varied with age or according to whether or not the contact lived in the same household as a case. The protective effect was significantly higher among males, and was significantly greater for multibacillary than for paucibacillary leprosy.

Adolescent↗