Biomedical subjects

R Roy

Publications and source records attributed to R Roy.

At least 451 records · Page 25Linked to original sources

PubMedDate not supplied

Histopathologic findings in synthetic and biologic explanted grafts used in peripheral arterial reconstruction.

Surgically explanted vascular grafts, including 47 autografts, 14 allografts, 103 chemically processed human umbilical vein (HUV) grafts, and 406 polytetrafluoroethylene (PTFE) grafts, were studied histopathologically. Autografts, HUV, and PTFE grafts were implanted mostly in the femoropopliteal position, whereas allografts were used as a blood access for hemodialysis. The main cause for explantation in autografts (53.6%), HUV (74.8%), and PTFE (61.3%) was thrombosis, whereas allograft failure was usually related to aneurysmal degeneration (72.7%). The infection rates of HUV (20.9%) and PTFE (25%) grafts were higher than those of autografts (4.8%) and allografts (9.1%). Furthermore, bacterial colonization occurred more frequently in HUV (63.9%) and PTFE (64.7%) than in autografts (6.7%) and allografts (0%). Leukocyte infiltration was detected mostly in HUV (39.4%) and PTFE (27%) explants. Autografts and allografts both showed a 7.1% rate of lipid uptake, whereas lipid retention was observed in 84.9% of HUV and 79.8% of PTFE grafts. These results suggest that biologic vascular grafts are to be used preferentially in small diameter arterial reconstruction because of their resistance to bacterial colonization and lipid uptake.

Adult↗

PubMedDate not supplied

Measurement of CD11/CD18 integrin expression on the polymorphonuclear cell surface after incubation with synthetic vascular prostheses.

Polymorphonuclear (PMN) cell activation in the presence of synthetic vascular grafts was studied by using flow cytometry to measure CD11/CD18 leukocyte adhesion molecule expression at the cell surface. Polymorphonuclear cells isolated from the blood of 10 healthy human donors were incubated with six knitted polyester vascular prostheses (Vasculour II, Albumin-Coated Graft, Triaxial, Gelatin-Impregnated Gelseal, Dialine I, and Bovine Collagen-Impregnated Dialine II) for 60 min at 37 degrees C. The authors' study demonstrated that CD11/CD18 integrin expression varies among donors for a given vascular prosthesis, and that each donor has his or her own pattern of responsiveness toward synthetic vascular grafts. The current study indicates that PMN activation measured by CD11/CD18 integrin expression is a sensitive method of measuring the blood compatibility of a given foreign surface for a given patient.

Animals↗

PubMedDate not supplied

Noninvasive follow-up of tissue encapsulation of foreign materials. Are magnetic resonance imaging and spectroscopy breakthroughs?

The development of sensitive and noninvasive magnetic resonance (MR) techniques for the long- and short-term evaluation of vascular prostheses requires detailed knowledge of the evolutionary trend of the MR properties of the perigraft tissue during the healing process. To characterize changes in water MR properties, the water proton relaxation times, T1 and T2, of the muscle in the vicinity of an implanted polyester material were measured as a function of implantation time. To provide better insight into interpretation of the MR results, we carried out histologic and peripheral blood cell activation studies and tissue water content measurements. The MR results illustrated the sensitivity of the relaxation times to changes in cellular response to the presence of an implant. The evolutionary trend of these MR parameters exhibited two distinct phases. The crossover from phase I to phase II occurred around 10 days postimplantation. This crossover is attributed to the transition in the inflammatory response from the acute phase to the chronic phase. During the acute phase, the very high initial T1 and T2s (the slower relaxing component of the transverse relaxation time) values decreased significantly and steadily. The value of T1 dropped by a factor of 2, whereas T2s went down by a factor of 6. During the same time, the diffusion parameter, beta, remained constant. However, during the chronic phase, the diffusion parameter increased sharply. By 30 days postimplantation, the value of beta had increased by a factor of 10. The relaxation times, on the other hand, increased steadily with implantation time. Because the current MR results provide an in vivo and noninvasive follow-up of the healing process around the polyester implant material, they will be of considerable value in the early detection of vascular graft complications by MR imaging.

Animals↗

PubMedDate not supplied

Can collagen impregnated polyester arterial prostheses be recommended as small diameter blood conduits?

A collagen impregnated graft and its parent preclotted prosthesis were implanted as thoraco-abdominal bypasses in dogs for periods ranging from 4 hr to 6 months and evaluated for their ease of handling, imperviousness, and healing behavior in terms of luminal surface thrombogenicity using labeled platelets and fibrinogen, prostacyclin (PGI2) secretion, histomorphometric determination of internal capsule thickness, and histopathologic and scanning electron microscopic studies. The collagen impregnated graft was impervious to blood and both grafts showed excellent handling characteristics. Fibrin uptake was negligible on both grafts; however, platelet uptake was higher on the collagen impregnated graft than on the control graft at 4 and 24 hr. The healing behavior of the collagen impregnated graft was also found to be different than that of the control graft between 1 and 6 months post implantation. The development of a host collagenous internal capsule at the anastomoses, and a confluent endothelial lining, was observed in both grafts at 1 month; in later implantation periods, the healing of the medial region was found to be more irregular in the collagen impregnated grafts, showing a lower mean PGI2 secretion than the preclotted control grafts. Histomorphometric analysis showed the internal capsule on the collagen impregnated grafts to be thicker than on the control grafts for most periods of implantation. The current study illustrates that the healing process of collagen impregnated grafts is delayed and that bovine collagen has a stimulating effect on tissue encapsulation. Current impregnated polyester arterial prostheses therefore cannot be recommended as small diameter blood conduits.

Animals↗

PubMedDate not supplied

Use of supercritical fluid extraction as a method of cleaning anterior cruciate ligament prostheses: in vitro and in vivo validation.

The process of supercritical fluid extraction (SFE) using carbon dioxide as the mobile phase is finding increasing numbers of applications in a wide variety of industries for the extraction, separation, and cleaning of materials. This study assessed the usefulness of this approach in removing surface contaminants from a knitted polyester anterior cruciate ligament (ACL) prosthesis before packaging and sterilizing the product during manufacture. The physical, dimensional, and chemical properties of SFE treated compared with commercially scoured control samples were characterized using a number of textile test methods: electron spectroscopy for chemical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, and solvent extraction analysis. The biocompatibility of the samples was measured in terms of their ability to generate CD18 integrin expression on activated human polymorphonuclear cells, and their inflammatory response when implanted for up to 30 days in the knee joint of rats. SFE treatment was successful in removing most of the nonpolar contaminants from the ACL prosthesis and reducing the amount of residuals to a commercially acceptable level. However, some nitrogen containing compounds and polar salts were not removed by the SFE process. The results from the biocompatibility tests demonstrated that the cleaner SFE treated prosthesis induced significantly lower CD18 expression than the scoured control fabric, and was also associated with a milder inflammatory response and a more rapid rate of healing during the 30 day animal trial. Another effect of SFE processing was to cause the polyester device to shrink and lose porosity because of yarn contraction and modification of the polymer's microcrystalline structure.

Animals↗

PubMedDate not supplied

The influence of group size on children's competitive behavior.

The present research was designed to test the hypothesis that children would compete more in tetrads than in dyads. Twenty-two pairs of male and 14 pairs of female target children (N = 72) played a competitive game in both tetrads and dyads. Consistent with the hypothesis, male target children competed more in tetrads than in dyads. This hypothesis was not supported for females, however. Analyses of the dynamics of tetrads and dyads further demonstrated that based on a global measure of smiling, the emotional atmosphere was less positive in tetrads than in dyads. The causes and consequences of interaction in different sized social groups are discussed.

Child↗

PubMedDate not supplied

Diagnostic imaging of breast cancer using fluorescence-enhanced optical tomography: phantom studies.

Molecular targeting with exogenous near-infrared excitable fluorescent agents using time-dependent imaging techniques may enable diagnostic imaging of breast cancer and prognostic imaging of sentinel lymph nodes within the breast. However, prior to the administration of unproven contrast agents, phantom studies on clinically relevant volumes are essential to assess the benefits of fluorescence-enhanced optical imaging in humans. Diagnostic 3-D fluorescence-enhanced optical tomography is demonstrated using 0.5 to 1 cm(3) single and multiple targets differentiated from their surroundings by indocyanine green (micromolar) in a breast-shaped phantom (10-cm diameter). Fluorescence measurements of referenced ac intensity and phase shift were acquired in response to point illumination measurement geometry using a homodyned intensified charge-coupled device system modulated at 100 MHz. Bayesian reconstructions show artifact-free 3-D images (3857 unknowns) from 3-D boundary surface measurements (126 to 439). In a reflectance geometry appropriate for prognostic imaging of lymph node involvement, fluorescence measurements were likewise acquired from the surface of a semi-infinite phantom (8x8x8 cm(3)) in response to area illumination (12 cm(2)) by excitation light. Tomographic 3-D reconstructions (24,123 unknowns) were recovered from 2-D boundary surface measurements (3194) using the modified truncated Newton's method. These studies represent the first 3-D tomographic images from physiologically relevant geometries for breast imaging.

Algorithms↗

PubMedDate not supplied

Results of a triple blind clinical study of myoblast transplantations without immunosuppressive treatment in young boys with Duchenne muscular dystrophy.

The effects of myoblast transplantations without an immunosuppressive treatment on muscle strength, and the formation of dystrophin-positive fibers was studied in five young boys with Duchenne muscular dystrophy (DMD) using a triple blind design. Injections of myoblasts were made into one biceps brachii (BB), and the opposite BB, used as a control, was sham-injected; the experimenters and the patient were blind to the myoblast-injected side. At the same time, myoblasts were also injected in the left tibialis anterior (TA) of these patients. The strength developed during maximal static contractions of the elbow flexor and extensor muscles was measured with a Kin-Com dynamometer. No increase in static elbow flexion torque was measured at any time from 2 mo up to 18 mo after the transplantation. One month after the transplantation, the percentage of dystrophin-positive fibers in the myoblast-injected TA ranged from 0 to 36%, while it ranged from 0 to 4% on the control side. The expression of dystrophin in these fibers, however, was generally low, and most likely less than 10% of the normal level. In the biceps brachii of both sides 6 mo after the transplantation, less than 1.5% of dystrophin-positive fibers were detected. The injections also triggered a humoral immune response of the host. Antibodies were capable of fixing the complement, and of lysing the newly formed myotubes. One of the antigens recognized by this immune response is possibly dystrophin. These results strongly suggest that myoblast transplantations, as well as gene therapy for DMD, cannot be done without immunosuppression.

Biopsy↗

PubMedDate not supplied

Many faces of depression in patients with chronic pain.

Depression is commonly associated with chronic pain patients. How common is it and what are its manifestations? Research findings are unclear. Besides, depression is defined by some as a syndrome and by others as an affect or symptom. This leads to further confusion. This paper attempts to answer those questions by a selected review of the pertinent literature and case examples to demonstrate reactive, clinical and masked depression and also depression as an affect or symptom. Some of the treatment issues are considered.

Adjustment Disorders↗

PubMedDate not supplied

Measurement of chronic pain in pain-depression literature during the 1980s: a review.

Measurement of pain is a new area of study. This review is based on a survey of pain-depression literature of the 80s. In general terms, measurement of pain is a neglected field. In most of the studies reviewed here pain is either not measured or measured somewhat crudely. Only in a minority of studies is there evidence of recognition that pain-measurement is a critical part of the overall clinical evaluation of chronic pain patients.

Chronic Disease↗

PubMedDate not supplied

Use of myxalin for improving vascular graft healing: evaluation of biocompatibility in rats.

Myxalin is a glycopeptide extracted recently from a gram-negative bacterium. It has blood anticoagulant properties and can enhance endothelial cell growth. With the ultimate objective of using this bioactive molecule to promote vascular graft healing, this study assessed its biocompatibility in vivo by comparing the cellular and immunological responses of gelatin-coated knitted polyester grafts with and without myxalin following implantation in the peritoneal cavity of rats for prescheduled periods of 3 days and 1, 2, and 4 weeks. A nongelatin-coated virgin polyester graft was included as the reference material. The biological response to gelatin alone was characterized by a slower rate of cellular infiltration into the implant, reduced collagen synthesis, and higher levels of acid phosphatase and esterase activity in the surrounding tissue. The addition of myxalin to this coating resulted in a significant reduction of hydrolase secretion in the tissue surrounding the implant and an enhancement of cellular ingrowth.

Acid Phosphatase↗

PubMedDate not supplied

Fresh venous allografts as arterial substitutes in dogs: the importance of donor-recipient tissue compatibility.

Fresh venous allografts were investigated in dogs matched according to donor-recipient tissue compatibility, either originating from the same litter or chosen at random (pound dogs). Five centimeter long segments of femoral vein were interposed as carotid substitutes in an autografting and allografting manner between paired dogs. During a 5-month implantation period, donor-specific antibody development was measured in the recipient serum by a flow-cytometric assay using cultured donor vascular endothelial cells. Autografts and allografts were investigated in terms of patency, histopathology, and endothelial cell function. Fifteen of 16 autografts remained patent. Allografts between littermate dogs, whether compatible or incompatible, showed no donor-specific antibody development and were all patent at retrieval. Compatible and incompatible allografts in littermates did not show any difference in prostacyclin (PGI2)/thromboxane A2 (TXA2) ratios. In pound dogs, both compatible allografts were patent and one dog developed donor-specific antivascular endothelial cell antibodies. Among incompatible dogs, antibody formation was detected at 1 month in five of six recipients and graft patency was as follows: two partial thromboses, two stenoses, and two patent grafts. The PGI2/TXA2 ratio was significantly lower in incompatible allografts than in compatible ones (p = .028). These results show the importance of donor-recipient histocompatibility matching in improving the outcome of vein allografts.

Animals↗

PubMedDate not supplied

Spatial expression of a DNA repair gene, N-methylpurine-DNA glycosylase (MPG) during development in mice.

BACKGROUND: DNA repair is a crucial phenomenon that maintains the chromosome integrity of genome which are continuously damaged by endogenous and exogenous alkylating agents. If the damaged DNA is not repaired, it may lead to mutation, chromosomal aberration, aging and cancer. N-methylpurine-DNA glycosylase (MPG), a ubiquitous DNA repair enzyme, removes N-methylpurine and other damaged purines in DNA. MATERIALS AND METHODS: MPG mRNA expression was revealed at various stages of mouse development from day 7.5 p.c. (post coitum) embryo to day 400 mature adult by Northern blot hybridization or RT-PCR. RESULTS: MPG transcripts were abundant in the mouse embryo during pregnancy and in adult testis and ovary. The MPG mRNA level in the testis was low in 1-week-old mice, but the level showed its maximum among the organs tested in 4-week-old young adults. In placenta, the level of MPG mRNA continuously decreased from day 7.5 p.c. to day 17.5 p.c. CONCLUSIONS: The spatial expression of MPG gene is highly regulated. Transcription of MPG is maximum in rapidly dividing and growing tissues during development. These data suggest that an elevated rate of MPG transcription is required for DNA replication.

Animals↗

PubMedDate not supplied

Gene amplification and expression of the DNA repair enzyme, N-methylpurine-DNA glycosylase (MPG) in HPV-infected cervical neoplasias.

BACKGROUND: Lethal and mutagenic damages of DNA is caused by a variety of agents including viruses. It is known that HPV is one of the major causes of cervical carcinogenesis and that cells eliminate DNA lesions with DNA repair enzymes. However, the role of N-methylpurine-DNA glycosylase (MPG) is not known in the development of cervical cancer. MATERIALS AND METHODS: Multiplex polymerase chain reaction (PCR) was used for the detection and typing of HPV in the biopsy. Gene amplification of MPG was measured by a PCR-based assay. The mRNA levels of MPG were determined by reverse transcription-PCR using hypoxanthine-guanine phosphoribosyl transferase as the reference gene. An immunohistochemical technique was used to examine the distribution of MPG in the tissues. RESULTS: Of 68 Korean cervical neoplasia patients, 86.8% showed HPV infection. High-risk HPV 16/18 were the most prevalent but positive only in 47.3% of the invasive cancer patients. Gene amplification of MPG was significantly increased in high-risk HPV-infected tissues as compared to low-risk HPV-infected and normal tissues (p < 0.05). The mRNA levels of MPG were higher in HPV-infected invasive carcinoma than normal cervical tissues. Immunohistochemical staining revealed that the intracellular expression and distribution (localization) of MPG altered in the cervical neoplasia. Interestingly, MPG expression in CIN III and invasive carcinoma (IC) was much higher than normal and CIN I. Granular positivity of MPG was notable in the perinuclear regions of the cytoplasm in HPV-infected invasive cancer. CONCLUSION: This is the first report on MPG expression in cervical neoplasia. Our results indicate that the gene amplification and expression of MPG were increased in high-risk HPV-infected cervical neoplasias and the intracellular distribution of MPG protein was altered, suggesting a role of MPG in carcinogenesis.

DNA Glycosylases↗

PubMedDate not supplied

[From micro- to macro-reconstitution of families: the SOREP system].

"This article outlines a new system for computerized family reconstitution. It has been developed in the last ten years by a multidisciplinary team of Quebec researchers belonging to the inter-university research center on populations (SOREP). Basically, this system is characterized by: a) an attempt to computerize as much as possible every step involved in the process of reconstitution, b) a set of tools devised for identifying and measuring all forms and degrees of similarity between names and surnames, c) a technique to process cases of ambiguous links, d) a set of programs used to assess the quality of the data and the strength of the links created, [and] e) an attempt to maximize the performance of the linkage work in terms of both efficiency and accuracy. The system has been designed to support several kinds of analyses, from social history and demography to population genetics. Our paper contains a brief overview of the current state of research in the field of record linkage, an introduction to the Saguenay [Canada] population register and a description of the system itself which has been utilized successfully in the last year on the 660,000 Saguenay parish records, covering the period 1842-1971." (SUMMARY IN ENG AND ITA)

Americas↗

PubMedDate not supplied

[Computerized family reconstitution on a large data-base: the SOREP system].

This article outlines a new system for computerized family reconstitution. It has been developed in the last 10 years by a multidisciplinary team of Quebec researchers belonging to the Inter-University Research Center on Populations (SOREP). Basically, this system is characterized by 1) an attempt to computerize as much as possible every step involved in the process of reconstitution, 2) a set of tools devised for identifying and measuring all forms and degrees of similarity between names and surnames, 3) a technique to process cases of ambiguous links, 4) a set of programs used to assess the quality of the data and the strength of the links created, and 5) an attempt to maximize the performance of the linkage work in terms of both efficiency and accuracy. The system has been designed to support several kinds of analyses, from social history and demography to population genetics. The paper contains a brief overview of the current state of research in the field record linkage, an introduction to the Saguenay population register, and a description of the system itself which has utilized sucessfully in the last year on the 660,000 Saguenay parish records, covering the period 1842-1971.

Americas↗

PubMedDate not supplied

[The reproduction of families affected by Steinert's dystrophy in Saguenay (Quebec), 1885-1971: demographic parameters].

"In the light of the literature in the field, one would expect that the myotonic dystrophy (or Steinert) gene carries a severe selective disadvantage. Indeed, this phenotype is commonly said to entail...sterility, infant mortality, and a lower nuptiality. In the worst cases, it is not unlikely that the gene could eliminate itself through non-reproduction. [A model is developed and] tested in the Saguenay (Quebec) population, known for its exceptionally high prevelance (1/475) of the disease. Authors have been able to use a computerized demographic and genealogical data base in order to study several demographic variables (fertility, nuptiality, mortality, etc)....Case-control analyses produced very [few] differences between affected and control families, suggesting no significant selective disadvantage associated with the gene." (SUMMARY IN ENG AND ITA)

Americas↗

PubMedDate not supplied

Fresh venous femoral autografts and allografts as carotid substitutes in matched dogs from the same litter.

Pathological and biochemical investigations were performed on femoral veins used as fresh autografts and allograft substitutes in the carotid arteries of dogs from the same litter and separated in two groups described as compatible and incompatible after a mixed leukocyte culture (MLC). After 5 months of implantation, all the arterial substitutes were patent. The analyses gave the following results: 1. The haematologic parameters were not affected by the grafts. 2. Light microscopy (LM) and scanning electron microscopy (SEM) indicate a thrombotic accumulation and the presence of inflammatory cells in the compatible and the incompatible allografts. The occurrence of pathological changes was more pronounced in the incompatible group. 3. Immunostaining of anti-factor VIII-related antigen reveals a better preservation of the endothelial cell wall on the autograft. 4. The 6-keto-PGF1 alpha/TXB2 ratios of the autografts and the compatible allografts were similar.

6-Ketoprostaglandin F1 alpha↗