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Biomedical subjects

A Berger

Publications and source records attributed to A Berger.

At least 343 records · Page 19Linked to original sources
PubMed1994

Peripheral nerve allografts: survey of present state in an experimental model of the rat.

Rejection and regeneration processes in peripheral nerve allografts are analyzed in this review of a series of experiments with special reference to the possible clinical application of peripheral nerve allografting in clinical reconstructive surgery. A long segment of the sciatic nerve (2.5 cm) was grafted between congenic rat strains across a maximal genetic barrier; immunohistologically, donor- and recipient-derived structures can be differentiated. If allografting was performed without immunosuppression, a rejection response with consecutive regeneration of minor quality was observed. Under immunosuppression with cyclosporin A no rejection response was observed and regeneration quality was comparable to control autografts. The persistence of donor-derived Schwann cells in the immunosuppressed allografts can be demonstrated immunohistologically. After discontinuation of immunosuppression a rejection response is exerted. We conclude that Schwann cells are eliminated from peripheral nerves during rejection. Consecutive regeneration of minor quality is possible, which implies the ingrowth of recipient-derived Schwann cells into the rejected allograft. Under immunosuppression, allogenic Schwann cells survive and actively promote regeneration. They are still immunologically competent and can exert rejection when immunosuppression is discontinued. A certain degree of replacement of donor-derived Schwann cells seems possible.

Animals↗
PubMed1994

Techniques of postoperative blood flow monitoring after free tissue transfer: an overview.

Ever since free tissue transfer has been established in microsurgery, success rates have greatly improved over the years, partly due to improved technical performance of microvascular anastomoses with better optical and instrumental aids. However, flap failure still occurs in 5-10%, mainly due to blood vessel thrombosis within the first 24 postoperative hours. Salvation rates of failing free tissue transfers can be optimized by in-time diagnosis of irreversibly compromised tissue blood flow and immediate operative reexploration. Therefore, there is a special demand for adequate and reliable postoperative monitoring techniques. This article gives an overview of all monitoring techniques, which have been performed both in the experimental and clinical setting thus far.

Body Temperature↗
PubMed1994

Interphase cytogenetic study of childhood acute lymphoblastic leukemia.

We used the fluorescence in situ hybridization (FISH) technique and centromere-specific probes for chromosomes 1, 6, 8, 10, 12, 17, 18, X, and Y to investigate the presence and number of the respective chromosomes in interphase nuclei of 14 cases of childhood acute lymphoblastic leukemia (ALL) which were shown to be hyperdiploid by DNA flow cytometry irrespective of their cytogenetic pattern. Numerical anomalies for one or more chromosomes were detected in all 14 cases. The FISH results were compared with those obtained by conventional cytogenetic analysis. A hyperdiploid karyotype was evident in 5 cases, the others were either normal or lacking cytogenetic results because of technical failure. In the 5 cytogenetically hyperdiploid cases, 14 numerical abnormalities were observed with both techniques, whereas 4 numerical deviations were found only with FISH. In 9 other cases which had a DNA content indicating hyperdiploidy, 34 trisomies and 2 tetrasomies were detected by FISH analysis. Furthermore, in 1 case duplication of the Y chromosome and in 3 male cases duplication of the X chromosome were evident. Double-target FISH experiments in 2 patients allowed the correlation of numerical aberrations of 2 chromosomes in one and the same cell. By such analyses, detection of subpopulations of tumor cells was found to be relatively easy. Our results indicate that the FISH technique with chromosome-specific repetitive centromeric probes is a rapid, simple to use, and easy to interpret technique for the evaluation of numerical chromosomal aberrations in interphase nuclei of leukemias.

Aneuploidy↗
PubMed1994

Sphingosine-1-phosphate, a novel second messenger involved in cell growth regulation and signal transduction, affects growth and invasiveness of human breast cancer cells.

This review will focus on the role of sphingosine and its phosphorylated derivative sphingosine-1-phosphate (SPP) in cell growth regulation and signal transduction. We will show that many of the effects attributed to sphingosine in quiescent Swiss 3T3 fibroblasts are mediated via its conversion to SPP. We propose that SPP has appropriate properties to function as an intracellular second messenger based on the following: it elicits diverse cellular responses; it is rapidly produced from sphingosine by a specific kinase and rapidly degraded by a specific lyase; its concentration is low in quiescent cells but increases rapidly and transiently in response to the growth factors, fetal calf serum (FCS) and platelet derived growth factor (PDGF); it releases Ca2+ from internal sources in an InsP3-independent manner; and finally, it may link sphingolipid signaling pathways to cellular ras-mediated signaling pathways by elevating phosphatidic acid levels. The effects of this novel second messenger on growth, differentiation and invasion of human breast cancer cells will be discussed.

3T3 Cells↗
PubMed1994

The use of acellular autologous skeletal muscle grafts in peripheral nerve repair: a morphometrical-morphological study.

Alternative materials for autologous nerve grafts in peripheral nerve surgery have long been investigated. This report describes the use of acellular (freeze-thawed) autologous skeletal muscle grafts (ASMG) to bridge a 2 cm gap in the sciatic nerve of rats. Neurophysiologic and morphometric studies performed 6 weeks after surgical procedure showed for the nine treated Sprague-Dawley rats (Group A) a good axon regeneration rate, although this was lower than that for the control group (Group B), a lower Nerve Conduction Velocity (NCV) and a thinner myelin sheath than in group B (n = 9 Sprague-Dawley rats). In the latter case, complete resection of 2 cm of the sciatic nerve was followed by an immediate coaptation of the proximal and distal ends.

Animals↗
PubMed1994

Element concentrations in the xylem sap of Picea abies (L.) Karst. seedlings extracted by various methods under different environmental conditions.

We used a Scholander pressure chamber to assess the effects of various extraction methods under different environmental conditions on element concentrations in xylem sap of 3-year-old Picea abies (L.) Karst. seedlings. Sap from excised shoots contained higher element concentrations when extracted at low than at high over-pressures. When comparing plants differing in water status, we found that a high extraction over-pressure introduced a systematic error into the data. For example, in well-watered non-transpiring plants relative to unwatered transpiring plants, potassium concentrations were 70% higher in sap extracted at 0.1 MPa over-pressure, but only 10% higher in sap extracted at 1.0 MPa over-pressure. Moreover, treatment effects depended on the time of day when the sap was extracted. Increased water flux in transpiring plants relative to non-transpiring plants resulted in reduced xylem sap element concentrations when samples were collected after 9 h of transpiration, but not after 4 to 6 h of transpiration. Drought had little effect on xylem sap element concentrations, indicating that rates of element release into xylem conduits, element depletion by growing tissues, and water flow maintained a balance that may prevent nutrient stress during short-term drought.

Journal Article↗
PubMed1994

Free vascularized mesentery transfer for closure of wide peritoneal wall defects.

The repair of large abdominal defects can often present problems related to the availability of local tissues adequate for filling the gap without creating high abdominal tension and pressure. The use of a free vascularized mesentery flap for restoration of the abdominal wall, in a case of an infiltrating carcinoid of the right upper and middle abdomen, is reported. After anastomosing the mesentery donor vessels to the deep inferior epigastric artery and vein, the subcutaneous and cutaneous layers were sutured primarily. Closure of the peritoneal cavity by means of vascularized undamaged visceral peritoneum should avoid infection and the formation of adhesions.

Abdominal Neoplasms↗
PubMed1994

[Rectovaginal fistulas in adults].

Recto-vaginal fistulas have multiple causes and a wide range of clinical and anatomical features. Simple fistulas, defined by a low situation, a traumatic origin, and a small size are accessible to simple means of cure. They can be operated from a vaginal approach, with conversion into a third degree perineal tear followed by repair of the perineal body, and the anal canal; they can be managed from a transanal approach, using endorectal flap advancement technique. Complex fistulas, defined by the etiology (IBD, radiation enteritis, cancer, postoperative), a high situation, or a large size, require larger and more sophisticated operations such as a combined abdomino-perineal approach or a muscle flap technique. Among the numerous techniques described for the cure of recto-vaginal fistulas, the authors emphasize those currently used by the most experienced teams of colo-rectal or gynecological surgeons.

Adult↗
PubMed1994

[Pulsed-field gel electrophoresis for the epidemiological analysis of yeast isolates].

Up to now, pulsed field gel electrophoresis (PFGE) has been used successfully for the analysis of the chains of infection of multiresistant staphylococci, enterococci and other germs involved in hospitalism. The purpose of this study was to find out whether yeast isolates from mothers and those from their newborns differed in genotypes. In this investigation, 103 parturient mothers and their children were examined for colonization by yeasts in sampling the vaginal secret at delivery and by taking swabs from the oral mucosa and the anus of the children on the third day after parturition. The samples were cultured on Sabouraud glucose agar and incubated for 48 hrs at 37 degrees C. The differentiation of the isolates was done biochemically by means of the VITEK-AMS system and morphologically on rice-extract agar. Subsequently DNA-fingerprinting analysis was carried out. In 6 cases we could prove the presence of Candida spp. in the mothers as well as in their children. In all cases the strains from mother and child showed the same banding pattern. Likewise, the strains isolated out of the vaginal secretion and the vaginal epithelium of individual women were identical. The differences observed between strains isolated from various women were of low or medium degree. This shows the PFGE to be an efficient procedure to demonstrate the relation of strains derived from mothers and their newborns.

Anal Canal↗
PubMed1994

[Surgical therapy of chronic anal fissure--do additional proctologic operations impair continence?].

78 patients with chronic anal fissures have been mainly operated on by lateral internal sphincterotomy (LATS). Continence have been evaluated by questionnaire at least 9 months postoperatively. Patient without any additional proctological operation had minor disturbances of continence in 17%. Patient with additional operations had disturbances of continence in 30%. Especially the subgroup of patients with LATS and haemorrhoidectomy had bad results. In this group only 45% were fully continent.

Adult↗
PubMed1994

[Microsurgical tissue transplantation for correction of hand abnormalities].

Established procedures in hand surgery are dominating the management of congenital anomalies of the hand. In complex deficiencies and in certain forms of thumb hypoplasia however, replacement of structures capable of growing is needed, as can be free transplantation of vascularized metatarsal bone or free toe transplantation as substitute for a whole part of a limb. Capabilities of and limitations to microsurgical procedures are presented in selected cases.

Adolescent↗
PubMed1994

[Regeneration of peripheral nerves after interposition of acellular muscle into larger defects].

Peripheral nerve grafting is an established procedure in reconstructive surgery. Nerve grafts, however, are only available to a limited extent and patients are faced with neurologic deficits at the donor areas. Pretreated skeletal muscle has been proposed as an alternative grafting material. In nine adult Sprague-Dawley rats, a 2 cm gap of the sciatic nerve is grafted with a M. gracilis segment which has been pretreated through repeated freezing and thawing. Regeneration is evaluated after six weeks postoperatively. The results are compared to nine conventional nerve grafts. Regeneration was evident in all grafts. Histologically, the muscle grafts revealed a high proportion of connective tissue, a good vascularisation but an inferior degree of myelinisation. Morphometrically, the muscle grafts proved to be inferior according to axon counts and myelinisation. Muscle grafts provide a substrate comparable to peripheral nerves regarding the tubular architecture based on laminin. There are however no viable Schwann cells within these substitutes, which makes them inferior compared to conventional nerve grafts for peripheral nerve repair. These results are discussed with respect to further experiments concerning allogeneic nerve grafting and peripheral nerve preservation.

Animals↗
PubMed1994

[The Dellon tube in injuries of peripheral nerves].

Experimental efforts are being undertaken to improve nerve transplantation as a method for peripheral nerve repair. Major disadvantages of nerve transplantation are the creation of neurologic deficits at the donor site and the limited availability of nerve grafts. Mackinnon and Dellon propose the interposition of synthetic, biodegradable tubes as a nerve conduit for clinical use. This method is described according to its theoretical background and the surgical technique. The interposition of synthetic tubes seems possible for short defects in finger nerves, but will render unfavourable results in long defects of peripheral mixed nerves.

Animals↗
PubMed1994

[Pulley for strengthening a muscle replacement operation across two joints in brachial plexus lesion: description of the surgical technique].

The reconstruction of lost muscle functions in cases of brachial plexus lesion is possible even in those cases where primary nerve reconstruction was not performed or unsuccessful. If there are only few motor nerves available, we prefer free latissimus dorsi transplantation or pedicled latissimus dorsi transposition for replacement of biceps and finger flexors. The combination of elbow flexion and finger flexion becomes possible when the transposed motor is passed around a suitable pulley in the elbow region like the flexor carpi ulnaris or carpi radialis.

Adult↗
PubMed1993

Enzymhistochemical evaluation of ulnar nerve grafts in brachial plexus lesions.

Our concept for the reconstruction of brachial plexus injuries includes an intercostal nerve transfer to the vascularized ulnar nerve graft. A free neurovascular latissimus dorsi is then transferred in a second stage operation. For optimization of the regeneration result, the operative planning of the second step includes nerve biopsies and enzymhistochemical evaluation for the distribution of motor axons. The staining method according to Scabolcz et al. is described and clinical cases are presented.

Brachial Plexus↗
PubMed1993

Preservation of peripheral nerve grafts with Schwann cell culture medium.

Preservation of peripheral nerves may, in the near future, play an important role in reconstructive surgery, especially if recent advances in immunosuppressive therapy are taken into account. Therefore, it has to be investigated whether peripheral nerves can be stored for some time after harvesting without diminishing their regenerative potential. Previous experiments of our group could demonstrate only little benefit of organ storage solution (HTK) or normal saline (NaCl 0.9%) to peripheral nerves when kept at cold ischaemia of 4 degrees C for 32 and 72 hours. In this presentation, we are reporting the results of peripheral nerve storage in Dulbecco's Modified Eagle Medium which has been used for Schwann cell culture. In 30 adult Sprague-Dawley rats, a 2.5 cm segment of the right sciatic nerve was harvested and kept at 4 degrees C for 14, 32, 72, and 120 hours. It was then reimplanted into the donor animal; regeneration quality was assessed clinically, histologically and morphometrically after 6 weeks. Best regeneration results were obtained in the 32 and 72 hour groups; regeneration here was comparable to the normal controls. These results are explained with the positive effect of nerve predegeneration.

Animals↗
PubMed1993

[Genesis and treatment of hand para-articular, painful tendon and tendon sheath changes].

Many patients suffer from wrist disorders caused by tendon- and tendon-sheath-affections. Apart from this the successful treatment of these affections is an important implication concerning national economy. In Lower Saxony 2.3% of all RVO-insured patients have these disorders. Most tendon- and tendon-sheath-affections are due to chronic stress which is generally treated by a non-operative therapy. Only some need be treated by a surgical intervention. In this paper the most frequent painful tendon- and tendon-sheath-diseases are listed, their clinical appearance is shown and the different methods of treatment are discussed.

Adult↗