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Biomedical subjects

G Feifel

Publications and source records attributed to G Feifel.

At least 19 recordsLinked to original sources
PubMed1992

Distribution pattern of capillary and venular red blood cell velocity following ischemia-reperfusion in striated muscle.

Ischemia-reperfusion induced changes in distribution pattern of RBC-velocity of nutritive capillaries and postcapillary venules was analyzed in striated muscle using intravital fluorescence microscopy in awake hamsters. Four hours of ischemia to striated muscle contained in the dorsal skinfold preparation (n = 10) revealed a significant (p < 0.01) decrease of capillary, but only a slight decrease of mean venular RBC-velocity during the entire reperfusion period. However, analysis of distribution pattern of single values revealed a shift of the histograms to the left, including pronounced skewness as mean values approached zero. This characteristic phenomenon may be due to an increase of microvascular hematocrit and/or decrease in deformability of red blood cells during ischemia-reperfusion. Beside other factors, the impairment of flow properties and flow conditions of the blood may contribute to the development of microvascular reperfusion injury.

Animals↗
PubMed1992

Influence of cryopreservation on viability and nutritional microcirculation of islets of Langerhans.

Isolated pancreatic islets of Syrian golden hamsters were cryopreserved for 1 and 10 weeks, respectively. Following thawing islet mass was found more than 90%. Analysis of viability of these islets by dithizone staining revealed 94 +/- 4% (1 week cryopreservation) and 96 +/- 3% (10 weeks cryopreservation) positively stained islets. After implantation into dorsal skin-fold chambers of syngeneic animals, intravital fluorescence microscopy (5% FITC-dextran, i.v.) showed a regular microvascular network 10 days after implantation. The total diameter of the microvascular network was found similar in cryopreserved islets (day 10: 420.8 +/- 55.2 microns (1 week preservation) and 406.5 +/- 25.2 (10 weeks preservation)) as compared to non-preserved controls (day 10: 411.7 +/- 53.9 microns). Therefore we conclude that cryopreservation of hamster islet isografts for 1 and 10 weeks, respectively, does not alter viability as well as the potential for revascularization. Cryopreservation seems to be an adequate technique for long time storage prior to free transplantation.

Animals↗
PubMed1992

Endosonographic differentiation of mucosal and transmural nonspecific inflammatory bowel disease.

Thirty-seven patients with nonspecific inflammatory bowel disease were examined with an ultrasonic colonoscope and the inflammation classified as mucosal or transmural. Mucosal inflammation was characterized by preservation of the five-layer structure of the wall with thickening of the submucosa. Transmural inflammation was endosonographically defined as sectional interruption or loss of the five-layer structure. In 14 of the 37 patients a colectomy was performed. Examination of 3 of the 14 resected specimens revealed inflammation confined to the mucosa. This was consistent in all three cases with the preoperative endosonographic evaluation. Eleven of the 14 resected specimens showed sectional transmural inflammation. Ultrasonographically all of the 11 patients fulfilled the criteria for transmural inflammation, whereas endoscopic and microscopic signs were consistent with transmural inflammation in 9 of the 11. Endosonography of the colon enables definition of mucosal inflammation thus providing criteria for selection of patient for ileoanal pouch construction.

Colon↗
PubMed1992

Cryopreservation of islets of Langerhans does not affect angiogenesis and revascularization after free transplantation.

Cryopreservation of isolated islets of Langerhans will be a necessary procedure if pancreatic islet transplantation crosses the threshold for clinical treatment of diabetes mellitus. Although successful cryopreservation of rodent, canine, porcine and human islets has been documented in the past few years, little is known about the influence of the freeze-thaw procedure on the islet's potential to induce angiogenesis and revascularization, a process which is of crucial importance after free transplantation. We have analyzed the process of revascularization of 1- and 10-week-cryopreserved hamster islet isografts using intravital fluorescence microscopy. First signs of angiogenesis of cryopreserved islet grafts were observed on day 2 after transplantation, characterized by the protrusion of capillary sprouts. During the following days these sprouts formed a microvascular network, and revascularization was completed on day 10 after transplantation. Quantitative analysis of functional capillary density, capillary red blood cell velocity, capillary diameter and flow of individual capillaries did neither show differences between 1- and 10-week-cryopreserved islets, nor differences between cryopreserved islets and islets transplanted without cryopreservation were observed. From these results we conclude that cryopreservation of isolated pancreatic islet grafts is an adequate technique for long-term storage prior to transplantation.

Animals↗
PubMed1991

[Initial experiences with a new monoclonal antibody in diagnosis of malignant melanomas].

In a study of 17 patients with malignant melanomas in the extremities the sensitivity and specificity of a new monoclonal antibody directed at melanoma cells (BW 575, Behring) were investigated. The specificity was 100%, but the sensitivity 70%. In 3 cases known foci could not be detected. All nodular melanomas and their metastases were detected (9 patients). Repeated examination during the first 24 h after injection of the Tc-99m-marked antibody, and two-plane investigations made it possible to detect even small tumors less than 1 cm in diameter and subcutaneous lesions where the melanomas absorbed the antibodies. Due to its high specificity, the antibody seems to be a promising aid in deciding the operative strategy.

Adult↗
PubMed1991

[Limited surgical radicality in occult cancer of Vater's papilla].

Nine histologically proven benign adenomas of the papilla of Vater were consecutively treated by transduodenal full thickness excision and simultaneous staging of regional lymph nodes without severe postoperative complications. 4 patients had a small well differentiated (pT1 GIpN0) carcinoma, although there was neither macroscopically nor by frozen sections any suspicion of a malignant tumour. A more radical pancreatoduodenectomy was not carried out and the 4 patients are without tumour recurrence or metastases 1-8 years postoperatively.

Adenoma↗
PubMed1991

[Ileostomy--stabilization by stapler technique].

In order to prevent nipple-sliding of the everted small bowel, conventional Brooke ileostomies in 26 patients were stabilized on both sides of the mesentery by longitudinal rows of staples. There were no early complications. With respect to historical controls with unstapled ileostomies, late complications (retraction, prolapse) could be reduced from about 16 to 0% in a median observation time of 2 years. The ileostomies were stable in size and form and therefore appliances were facilitated.

Crohn Disease↗
PubMed1991

[Changes in cell-mediated immune reactions in Crohn's disease].

In a prospective study the effect on cell-mediated immunity (Mérieux-Multitest), nutritional state and parameters of inflammation was compared in conservatively (n = 21) and surgically (n = 20) treated patients with Crohn's disease. Before therapy both groups showed a significantly lower immune response compared with healthy controls. The therapeutical effect was similar in both groups concerning normalization of parameters of inflammation, CDAI and state of nutrition. In contrast, normalization of immune response in skin test was only observed after bowel resection, while conservatively treated patients remained in hyperergy. In conclusion, the impairment of the cell mediated immunity in Crohn's disease must be secondary. Excluding patients with steroid therapy there was no correlation between preoperative annergy or hyperergy and postoperative complications.

Adult↗
PubMed1991

[Endosonography of the rectum].

Endorectal ultrasound is proving to be a very accurate method for the preoperative staging of cancer. The tumor penetration depth is assessed with an accuracy of more than 90% for all T stages. The preoperative endosonographic evaluation of lymph nodes is superior to other imaging modalities, being more than 80% accurate in comparison to CT and lymphoscintigraphy. It is relatively easy to perform and inexpensive compared with other imaging modalities. It has proved its influence on decision making, selection for local therapy, planning of radiotherapy and reoperation of early tumor recurrencies.

Humans↗
PubMed1991

[Complete reconstruction of the natural anus in complicated rectal prolapse].

In a 44-year old woman a severe case of prolapse of the rectum was complicated by complete incontinence and rectal stenosis. Continence was restored by colo-anal anastomosis between an oral smooth-muscle-plasty and the anal skin introduced in a newly created anal canal by a distal voluntary muscle-plasty. The successfully applied one-stage technique in reestablishing non-voluntary and voluntary muscular continence is described in detail.

Adult↗
PubMed1990

Endosonography of pararectal lymph nodes. In vitro and in vivo evaluation.

One hundred thirteen patients with carcinoma of the rectum were evaluated for lymph node metastases by endorectal ultrasound. With the use of 7.5 MHz and based on different echo patterns, two main groups of lymph nodes can be differentiated: hypoechoic and hyperechoic lymph nodes. Compared with pathologic findings, hypoechoic lymph nodes represent metastases, whereas hyperechoic lymph nodes are visualized due to unspecific inflammation. Lymph node metastases can be predicted with a sensitivity of 72 percent and inflammatory lymph nodes with a specificity of 83 percent. The physical basis of the differentiation of lymph nodes was assessed in vitro by the determination of ultrasound parameters (speed of sound, acoustic impedance, attenuation, and backscattered amplitude). The attenuation coefficient of benign lymph nodes [2.5 dB/(MHz x cm)] is significantly higher than the mean value of lymph node metastases [1.3 db/(MHz x cm)]. The results demonstrate that involved nodes can principally be differentiated from not involved nodes. Micrometastases, mixed lymph nodes, and changing echo patterns within inflammatory nodes explain the accuracy rate of 78 percent.

Acoustics↗
PubMed1990

A specific fluorescent dye for ex situ staining of vital islets of Langerhans: neutral red.

We present a new technique for specific ex situ fluorescent staining of islets of Langerhans with neutral red. Depending on the concentration of neutral red (1 microgram/ml), this technique allows the differentiation between exocrine and endocrine pancreatic tissue, according to differences in fluorescence intensity. Pancreatic islets can be stained not only in situ, but in particular ex situ after pancreas digestion. Since intravital staining of the pancreas in situ with neutral red is not applicable in human transplantation, the staining procedure ex situ may be a useful tool for islet purification by particle sorting, using a fluorescent-light-activated system; thus, a sufficient mass of purified islets for free transplantation may be isolated.

Animals↗
PubMed1990

[Mixing results of prospective and retrospective studies by objective decision analysis: evaluating probability by healthy human minds?].

The major shortcomings of formal decision analysis derive from the complexity of the clinical problem, behavioral qualities of the investigator and the method itself. It seems difficult to translate study results into a probability estimate for the problem in an individual patient. Therefore, probability assessments from the medical literature, one's own clinical experience and data sources should be combined. Decision analysis is not itself clinical reality but provides a model for thinking explicitly about the problem.

Clinical Competence↗
PubMed1989

Angiogenesis and hemodynamics of microvasculature of transplanted islets of Langerhans.

Transplantation of isolated islets of Langerhans is frequently followed by early loss of islet function. Because whether this is caused by insufficient vascularization or graft rejection is unknown, angiogenesis and microvascularization of islet grafts were studied in vivo by means of intravital microscopy. After transplantation of syngeneic islets in hamster dorsal skin-fold chambers, 97% (n = 66) of the islets exhibited the first signs of angiogenesis at days 2-4, characterized by sinusoidal sacculations and capillary sprouts. After 10 days, angiogenesis was completed, consisting of a microvascular network similar to those of islets in situ: arterial supply, afferent and efferent capillary loops, and venular drainage. Functional density of microvessels was 700.1 +/- 127.0 cm-1, and erythrocyte velocity was 0.58 +/- 0.35 mm/s. Intracellular insulin was demonstrated immunohistochemically. Electron-microscopic studies revealed normal fine structure of the capillary wall. The model allows in vivo analysis of microvascular phenomena occurring in host-vs.-graft reaction after allogeneic and xenogeneic islet transplantation. Furthermore, it may be used to quantitatively assess immunosuppressive regimens.

Animals↗