PubMed Health⌕ Search

Biomedical subjects

R H Christofferson

Publications and source records attributed to R H Christofferson.

7 recordsLinked to original sources
PubMed1999

Pretreatment, ultrasound-guided cutting needle biopsies in childhood renal tumors.

BACKGROUND: The current International Society of Paediatric Oncology (SIOP)-10 protocol does not allow pretreatment histological classification of low-stage renal tumors in children for fear of needle tract recurrences. The aims of this retrospective study were to evaluate the safety, sensitivity, and specificity of ultrasound-guided cutting needle biopsies (UCNB) performed at our institution in pediatric patients with renal tumors. PROCEDURE: Of 28 pediatric patients presenting with a renal tumor between 1988 and 1996, 25 underwent biopsy with the Biopty biopsy instrument (needle diameter 1.2 mm). The preoperative biopsy and nephrectomy slides were reviewed by a SIOP reference pathologist. The patients' hospital records were reviewed and biopsy complications were noted. RESULTS: At review of the nephrectomy slides, the diagnoses were: Wilms tumor (16 patients), with anaplasia in one case, rhabdoid tumor (2 patients), neuroblastoma (2 patients), mesoblastic nephroma (2 patients), clear cell sarcoma (1 patient), malignant teratoma (1 patient), and renal cell carcinoma (1 patient). No needle tract recurrence or other major complication was observed. The only complication was local pain at the biopsy site, which occurred in 24% (6/25) of the cases. The sensitivity of UCNB was 76% (19/25); five biopsies did not yield diagnostic material and one was not concordant. All cases of Wilms tumor were correctly diagnosed by UCNB, but only 33% (3/9) of the other tumors. CONCLUSIONS: In all cases of Wilms tumor a correct diagnosis was made. The overall sensitivity was 76%. UCNB proved to be a safe procedure that was not associated with needle tract recurrence or other serious complications.

Adolescent↗
PubMed1999

"No-touch" technique using saphenous vein harvested with its surrounding tissue for coronary artery bypass grafting maintains an intact endothelium.

Spasm and consequent dilation of the saphenous vein (SV) for coronary artery bypass grafting (CABG) can be avoided if the vein is harvested with its surrounding tissue. Morphologic techniques, including scanning and transmission electron microscopy, were used to compare endothelial cell integrity using three SV harvesting procedures: conventional (adventitial stripping of the vein, manual distention and storing in saline); intermediate (after adventitial stripping, the vein was left in situ, covered with a papaverine-soaked compress, and stored in heparinized blood); and "no-touch" (SV dissected with its surrounding tissue was left in situ, covered with a saline-soaked compress and stored in heparinized blood). Preservation of endothelial cell integrity was greater with the "no-touch" procedure than with the other methods. Since endothelial cell integrity of SV grafts may affect the patency rate, we conclude that the "no-touch" preparation should improve the results of CABG.

Anticoagulants↗
PubMed1998

Reduced mucosal perianastomotic capillary density in rat small intestine with chronic radiation damage.

Anastomoses in an intestine with chronic radiation damage are prone to leakage, possibly due to a reduced blood supply induced by a reduced capillary bed. In an animal model, the numerical capillary density in the perianastomotic area was investigated in intestine with or without chronic radiation damage. A 2-cm segment of rat ileum received a single dose of 21 Gy. Twenty weeks later, when the chronic radiation-induced changes were established, an anastomosis was constructed in this segment and in a corresponding segment in control rats. In situ perfusion fixation of the intestine was done 4 or 7 days after construction of the anastomosis, sections of the intestine were removed surgically, the specimens were embedded in methacrylate plastic and sectioned at 2.5 microm, and capillaries were counted under a light microscope. The circumferential mucosal capillary density was lower in irradiated than in nonirradiated animals at both 4 and 7 days (P < 0.001 and P = 0.04, respectively). This reduction was greater in the mesenteric quadrant than in the other quadrants around the circumference. These results are indicative of a reduced capillary bed in the vicinity of anastomoses in intestine with chronic radiation damage, which might lead to an impeded blood supply and subsequent leakage.

Anastomosis, Surgical↗
PubMed1997

Tumor growth in a defined microcirculation.

The fate of human tumor cells deposited in rat uteri was investigated by light microscopy of histological sections, immunohistochemistry, and scanning electron microscopy of microvascular corrosion casts. The human colonic tumor cell line LS 174 T was used as graft since it can be detected by CEA immunohistochemistry, and spayed nude rats (PVG rnu/rnu) were used as hosts, subjected to different hormonal regimens (no exogenous hormones, medroxyprogesterone acetate, 17-beta-estradiol, or the last two regimens in combination). Intrauterine deposition of a suspension of 2 x 10(6) tumor cells resulted in tumor take in 72% (21/29) of the nude rats. Endometrial growth was verified in only three animals (14%, 3/21). Extraendometrial growth, however, was found in all animals with tumor take. These observations suggest that the endometrium is comparatively resistant to growth of xenografted human colonic tumor cells. The tumor microcirculation consisted of new vessels, giving morphological evidence that tumor growth is dependent on angiogenesis and not on invasion of preexisting vessels.

Adenocarcinoma↗
PubMed1992

Vascularization of fetal neocortical grafts implanted in brain infarcts in spontaneously hypertensive rats.

The vascularization of neural grafts in ischemic brain was studied in spontaneously hypertensive rats grafted with a suspension of fetal neocortical tissue into the infarcted area five to six days after ligation of the middle cerebral artery. The brain vasculature was examined by scanning electron microscopy of corrosion vascular casts and the cortical microvasculature was stereologically quantified in light microscopy three months after the occlusion. Patent anastomoses were present between the middle cerebral artery distal to occlusion and the proximal part, as well as to the anterior and posterior cerebral arteries, in both grafted and non-grafted rats. A vascular plexus covering the infarct cavities and the grafts contained leptomeningeal vessels intermingled with a thin capillary network which is not normally found on the brain surface. The graft vessels were derived from this vascular plexus. The regular pattern of arterioles and venules penetrating from the cortical surface in normal neocortex was absent in the grafts but the capillary morphology was similar in both types of tissue. The grafts had a lower capillary density than normal tissue and lacked the laminar distribution of capillaries characteristic of normal neocortex. The results demonstrate the plasticity of the vascular system where remodeling of the vascular tree after an ischemic insult provides suitable conditions for the vascularization of neocortical grafts.

Animals↗
PubMed1988

Morphology of the endometrial microvasculature during early placentation in the rat.

The morphology of the uterine microvasculature during early placentation was investigated by light microscopy, scanning electron microscopy of microvascular corrosion casts and transmission electron microscopy in rats 26 and 50 h after initiation of implantation. Increased vascular permeability at implantation sites was observed as a positive blue-dye test, spacing of vessels, and as localized extravasations of resin from postcapillary venules in the center of the endometrium. The subepithelial capillary plexus in the primary decidual zone adjacent to the blastocyst was shut down 50 h after initiation of implantation, most probably due to swelling of the metabolically activated endothelium and volume expansion of the decidual cells. This phenomenon coincided with the mesometrial orientation of the inner cell mass of the blastocyst; it may be a uterine mechanism to direct the ectoplacental cone toward the patent vessels in the mesometrial portion of the uterus. The remaining vessels at implantation sites were generally fewer, larger in diameter, more irregular in caliber, and more uniformly oriented along the implantation axis than their counterparts at inter-implantation sites. No vascular sprouts were observed during the interval studied.

Animals↗