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Biomedical subjects

G Zimmermann

Publications and source records attributed to G Zimmermann.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Laparoscopic hernia surgery--status of minimal invasive techniques in a spectrum of surgical indications].

Endoscopic surgery led in the nineties to a discussion on surgical treatment of hernias. At the present time there are three groups of operative procedures: the conventional procedure--Shouldice, Bassini--the open tension-free procedure with implantation of a mesh--Lichtenstein, Gilbert-Rutkow--and the endoscopic procedure (predominantly transabdominal preperitoneal hernioplasty (TAPP) and total extraperitoneal hernioplasty (TEP)). The debate on the optimal therapy of hernias is understandable in view of the large number of hernia operations which are carried out. Numerous studies, some randomized, have demonstrated both the advantages and the disadvantages of the individual operative procedures. In addition to the recurrence rate and the complications, the cost factor and the associated socio-economic aspects of the particular operation play an increasingly important role in the decision on the method that should be used. In December 1995 some Austrian surgeons, who concerned themselves with problems of hernia repair already before the definitive introduction of laparoscopic hernia repair in today's surgery, came together on the occasion of a "Consensus Conference". During the meeting a summary of all relevant aspects of the complex of problems was worked out and summarized in a catalog of indications for the different operative interventions. The main statement was that the traditional open surgery, which can be performed under local anesthesia is indicated for an unilateral primary hernia. In case of an unclear finding at the contralateral side, as well as in case of a recurrent hernia, an endoscopic procedure is indicated. Meanwhile the Hernia Forum of Zürs ("Zürser Hernienforum") was founded. The function of this forum is the realization of a prospective randomized study for hernia repair in Austria.

Hernia, Inguinal↗
PubMed1996

Protein kinase C alters the responsiveness of adenylyl cyclases to G protein alpha and betagamma subunits.

The ability of protein kinase C (PKC) to regulate the responsiveness of adenylyl cyclase to different activators was assessed. Membranes prepared from Sf9 cells infected with recombinant baculoviruses encoding either type II or IV adenylyl cyclase were incubated with recombinant PKCalpha (purified from Sf9 cells), and the effects on adenylyl cyclase activity were measured after reconstitution with Gsalpha, Gbetagamma, or forskolin. PKCalpha treatment of type II adenylyl cyclase leads to increases in basal, forskolin-stimulated, and betagamma-stimulated activities and greater sensitivity to stimulation by Gsalpha. Paradoxically, most of the betagamma potentiation of Gsalpha-stimulated activity is eliminated by pretreatment with PKCalpha. By contrast, treatment of type IV adenylyl cyclase with PKCalpha has little effect on the basal, forskolin-stimulated, or betagamma-stimulated activities but markedly reduces the Gsalpha-stimulated and betagamma-potentiated activity of this isoform. These studies demonstrate that protein kinases can alter both the activity of adenylyl cyclase isoforms and their responsiveness to G protein regulation, thereby altering the ability of adenylyl cyclases to integrate signals derived from multiple hormonal inputs.

Adenylyl Cyclases↗
PubMed1996

The breast mucin MUCI as a novel adhesion ligand for endothelial intercellular adhesion molecule 1 in breast cancer.

The MUC 1 mucin is expressed on normal breast epithelium and in 90% of breast cancers. We report here that tumor-associated MUC1 is a ligand for intercellular adhesion molecule 1 (ICAM-1). Antibodies to ICAM-1 and to MUC1 inhibited adhesion of human and transfected mouse MUC1-positive cell lines to human umbilical vein endothelial cell monolayers and immobilized recombinant human ICAM-1-immunoglobulin fusion protein. Purified MUC1 pretreatment of recombinant human ICAM-1 was an equally effective inhibitor of adhesion. The interaction between MUC1 and ICAM-1 may be critical to the process of bloodborne metastases in breast cancer.

Animals↗
PubMed1996

Tachocomb used in endoscopic surgery.

BACKGROUND: Diffuse bleeding from parenchymatous organs or bleeding of the lung both in conventional and endoscopic surgery has to this day been treated with the usual methods - coagulation, tamponade, or oversewing. METHODS: With the development by the pharmaceutical industry of a collagen fleece coated with fibrin glue (Tachocomb), an additional method of hemostasis became available. RESULTS: The positive results obtained with the fibrin-coated collagen fleece in conventional surgery encouraged us to employ it when performing endoscopic operations. Especially with laparoscopic cholecystectomies, but also in other endoscopic operations, the application of Tachocomb has proved very successful. Nevertheless, the method of applying Tachocomb was not adequate, and limited its use, which made it necessary for us to develop an application system for endoscopic use. CONCLUSIONS: The application system, which consists of a fan as the Tachocomb carrier and a mounting support, worked well during the first tests. In order to confirm this, clinical studies will now be carried out.

Aprotinin↗
PubMed1996

Retrospective failure analysis in laparoscopic hernia repair possible because of routine videodocumentation.

BACKGROUND: Studies performed to date show that laparoscopic hernia repair is superior to conventional procedures with regard to postoperative pain, complications, and duration of inability to work. METHODS: From August 1, 1992, to February 16, 1995, we performed 245 laparoscopic hernia procedures on 224 patients utilizing a transabdominal preperitoneal polypropylene mesh-plasty (TAPP). RESULTS: We observed in the first 100 patients a total of 21 postoperative complications in 20 patients (21%). We observed 3 hernia occurrences (3%) in this group. Due to careful video documentation of all procedures, retrospective analysis of operative failure was possible. Working on the complications occurring resulted in a modification of the procedure, leading to a standardization of the operative technique and to a rigorous reduction in the number of complications and recurrences. CONCLUSIONS: Video-assisted retrospective failure analysis is consequently an effective method to use to optimize the results of minimal invasive hernia repair.

Adolescent↗
PubMed1996

[Tubular differentiated stomach carcinoma of the (Ming) infiltrating type].

Gastric carcinoma of the infiltrative type (according to Ming) occasionally shows adenomatous differentiation only. Over the past 18 years, we have observed 23 cases of this tumour type, accounting for 3.6% of all surgically treated gastric carcinomas. Macroscopically they were classified as Borrmann IV or III, while histologically most of them were well differentiated. Histologically, these tumours retained the pre-existing structures of the stomach, most readily observable at the tunica muscularis propria; a pronounced desmoplasia was also characteristic, particularly in the submucosal and subserosal layers. In all cases the tumour tissue spread inside lymphatic vessels. All but 2 cases with metastatically involved lymph nodes, often small, showed infiltration of the lymph node sinus; in three quarters of cases the serosa was infiltrated by the tumour. Significant findings among the patients under observation for extended periods included bilateral ovarian metastases in 4 of 5 women examined and tumour recurrence at the anastomosis in 6 of 9 patients in whom Billroth II operation had been performed. The mean survival time of 16 patients was 14.9 months. Owing to the diffuse type of tumour growth, extensive surgery is recommended as in cases of signet ring cell cancer. The high incidence of small lymph node metastases from this type of tumour should also be taken in account preoperative staging. Preoperative diagnosis of this tumour subtype is difficult, because histological criteria alone do not allow clear identification. Close cooperation with clinical investigators is necessary, and intraoperative assessment of the tumour--including frozen section of necessary--in particular is of the utmost importance.

Adenocarcinoma↗
PubMed1996

[Preoperative axillary ultrasound in breast carcinoma: value of the method in routine clinical practice].

AIM: To evaluate the significance of routinely performed preoperative axillary sonography in breast cancer patients. METHOD: 191 patients with surgical treated breast cancer were analysed retrospectively. 74 patients of these had an axillary sonography done by 5 different examiners. RESULTS: For detecting lymph node metastases sensitivity was 68.2% in all T-stages and 50% in T1-stages with a specificity of 100%. Classification of the axillary status (positive or negative for lymph node metastases) is possible in 90.5% for all T-stages and 94.9% for T1-stages. Microscopic and small lymph node metastases are missed by ultrasound. Compared to axillary palpation, sonography is better. CONCLUSION: Preoperative axillary sonography is an useful diagnostic method even when done routinely. If further criteria are considered, axillary dissection could be avoided in some patients.

Adult↗
PubMed1996

[Value of preoperative axilla ultrasound in breast carcinoma].

Preoperative axillary sonography is a superior method in predicting axillary lymph node status than clinical examination in patients with breast cancer. However, the results depend on the skills and care of the examiner, metastases less than 3-5 mm are hardly visible.

Axilla↗
PubMed1995

[The normal CT and ultrasonic findings after a laparoscopic inguinal hernia operation].

Common surgery has been revolutionised by minimal invasive surgery in a very short period of time. Laparoscopic operations of inguinal hernias are routinely done by many surgeons. For interpreting correctly postoperative complications with radiological techniques it is necessary to know the sonographical and CT changes of the normal postoperative situs. For evaluating these changes 23 patients without symptoms were examined between the first and third postoperative day. Typical sonographic findings are high echogenicity of the hernial orifice (17x) and echo-lucent thickening of the spermatic cord. The surgical clips and fleece and CO2 bubbles could not be detected by ultrasound. Using CT we found free peritoneal fluid collection (2x), streaky thickenings in the area of operation (20x), oedema at the hernial orifice (19x), residual CO2 bubbles (22x), thickening of the spermatic cord (22x) and visualisation of the surgical clips. The surgical fleece was invisible in all patients.

Adult↗
PubMed1994

TNF receptors TR60 and TR80 can mediate apoptosis via induction of distinct signal pathways.

TNF membrane receptors are usually co-expressed in many tissues but their relative contribution to cellular TNF responses is for most situations unknown. In a TNF cytotoxicity model of KYM-1, a human rhabdomyosarcoma cell line, we recently demonstrated that each of the two TNFRs is on its own capable of inducing cell death. Here we show that both receptors are able to induce apoptosis, as revealed from a similar onset of DNA fragmentation and typical morphologic criteria. To obtain additional information about the signaling pathways involved in TR60- and TR80-induced programmed cell death, we have used a series of selective inhibitors of intracellular signaling molecules. The overall pattern emerging from these experiments provides strong evidence for distinct signal pathway usage of TR60 and TR80, indicating protein kinase(s)-mediated control of TR60 signaling and a tight linkage of TR80 to arachidonate metabolism. The subsequent establishment of KYM-1-derived cell lines that display TNFR selective resistance further supports a segregation of TR60 and TR80 signaling pathways for induction of apoptotic cell death. Moreover, these results demonstrate an independent control of the distinct signaling cascades used by TR60 and TR80. This allows a highly flexible regulation of a cellular TNF response in those cases in which both receptors contribute to overall TNF responsiveness.

Apoptosis↗
PubMed1994

Monitoring of right ventricular function using a conventional slow response thermistor catheter.

OBJECTIVE: To investigate whether determination of right ventricular end-diastolic volume (RVEDV) and right ventricular ejection fraction (RVEF) can be performed with reasonable accuracy and reproducibility using a conventional slow response thermistor pulmonary artery catheter (CPAC) applying an adaptive algorithm. DESIGN: To study RVEDV and RVEF simultaneously with pulmonary artery catheters equipped with slow and fast response thermistors (FRPAC) under a broad range of cardiac output. SETTING: Laboratory of Institute of Experimental Surgery, Technical University. ANIMALS: 11 anaesthetised piglets. INTERVENTIONS: Hypovolemia (V-) was induced by withdrawal of blood up to 50 ml/kg, hypervolemia (V+) was produced by retransfusing blood and adding up to 30 mg/kg hydroxyethyl starch. In 5 animals in phases V- and V+ beta-adrenergic stimulation was achieved with dobutamine. Finally pulmonary artery hypertension was induced by infusion of small air bubbles. MEASUREMENTS AND RESULTS: Cardiac output (CO), RVEDV and RVEF were determined simultaneously with FRPAC and CPAC placed in the same pulmonary artery branch. Measurements were repeated 8 times sequentially in steady state normovolemia. A total of 130 measurements could be analysed. The coefficient of variation was 6.7 +/- 4.2% for CO(FRPAC) and 4.6 +/- 1.7% for CO(CPAC); for RVEF it was 9.7 +/- 6.2% (FRPAC) and 9.9 +/- 3.9% (CPAC); for RVEDV it was 11.6 +/- 4.8% (FRPAC) and 8.54 +/- 3.2 (CPAC). Mean difference (bias) was 0.06 +/- 0.39 l/min for CO measured with both methods, 19 +/- 35 ml for RVEDV and -3.3 +/- 6.5% for RVEF. CO(CPAC) displayed a strong correlation to CO(FRPAC) (R = 0.97, p = 0.001) as well as RVEF (R for RVEF(CPAC) versus RVEF(FRPAC) = 0.90, p = 0.001). R for RVEDV(CPAC) versus RVEDV(FRPAC) was 0.67, p = 0.001. We conclude that this animal study demonstrates good agreement between RVEF and RVEDV obtained with catheters equipped with a fast response thermistor or with a conventional slow response thermistor allowing accurate monitoring of right ventricular function with a conventional pulmonary artery catheter.

Algorithms↗
PubMed1993

Weak magnetic fields change extinction of a conditioned reaction and daytime melatonin levels in the rat.

Altogether 100 albino rats were conditioned to flee after an acoustic stimulus (1000 Hz). During the following retention period (extinction of the reaction), half of the animals (test group) were exposed to a vertically directed, weak and extremely low-frequency magnetic field (10 Hz, 10(-4) T). Under the field's influence, the animals showed an increased retention of conditioned reactions and had an elevated level of serum melatonin compared with the animals of the control group. These effects disappeared when the investigation was performed in the dark.

Acoustic Stimulation↗
PubMed1992

Random entry of circulating lymphocyte subsets into peripheral lymph nodes and Peyer's patches: no evidence in vivo of a tissue-specific migration of B and T lymphocytes at the level of high endothelial venules.

Lymphocytes continuously migrate through the body and thus immune competent cells are constantly delivered to most tissues. They interact with high endothelial venules (HEV) via specific homing receptors and vascular addressins, and these molecules seem to be the reason for a preferential homing of B lymphocytes into Peyer's patches and of T lymphocytes into peripheral lymph nodes. When lymphocytes derived from lymph node cell suspensions were applied in the in vitro lymphocyte/endothelium binding assay, the well-known preference of mouse lymph node B lymphocytes for Peyer's patch HEV compared to peripheral lymph node HEV was confirmed in the rat (2.8 times). When in the same in vitro assay thoracic duct lymphocytes (TDL) were used this preference was far less obvious (1.4 times). However, by injecting rat TDL intravenously and by tracing them directly in HEV, B, T, CD4+ and CD8+ lymphocytes are seen to enter Peyer's patches and peripheral lymph nodes in vivo without preference. Thus, in contrast to lymphocytes from lymph node cell suspensions, no evidence was found of a tissue-specific migration of thoracic duct B, T, CD4+ and CD8+ lymphocytes at the HEV level. This finding demonstrates the importance of considering both experimental conditions and the cell source used when investigating lymphocyte traffic.

Animals↗
PubMed1992

[Secretion of hCG by mononuclear cells--a specific and essential reaction in pregnancy?].

Mononuclear cells in peripheral blood secrete immunoreactive hCG (ir-hCG) when they are stimulated in in-vitro culture with the proteinkinase C - activator phorbol-myristat-acetate (TPA). We examined the ir-hCG secretion in 61 fertile and 191 pregnant women and 38 men. Mononuclear cells of pregnant women secrete after TPA stimulation significantly more ir-hCG than mononuclear cells on non-pregnant but fertile women. This effect can be detected as early as 23rd days of a menstrual cycle which is accompanied by conception and persisted over the entire duration of a pregnancy. Maximal effects were observed in the 7th to 19th and 30th to 34th weeks of pregnancy. An artefact caused by adhesive serum-hCG could be excluded. The elevated potential of the mononuclear cells to be stimulated remained intact for about 14 days after termination of a normal pregnancy in the first trimester. An ir-hCG secretion similar to that seen in nonpregnant women was found in patients with early abortion. The possible physiological importance of the in-vivo secretion of beta-HCG during pregnancy is discussed.

Abortion, Incomplete↗
PubMed1992

[Experiences with total parathyroidectomy and autotransplantation of intraoperatively selected parathyroid tissue in reactive renal hyperparathyroidism].

Surgery is indicated in cases of therapy-resistant reactive renal hyperparathyroidism with clinical symptoms and signs. The method of choice is total parathyroidectomy, with autotransplantation of parathyroid tissue into the forearm musculature. Twenty-two patients were parathyroidectomized. In 19 cases the intraoperative selection of tissue for autotransplantation was made by means of a stereoscopic magnifying glass. With one exception, only fragments of type 1a glands and type 1a-like areas obtained from type 2 glands were transplanted. In 18 of the 22 cases parathyroid hormone levels decreased from 1131 +/- 657 preoperatively to 87 +/- 53 pg/ml postoperatively. In 4 patients with postoperative values over 200 pg/ml a transplant-related recurrence of hyperparathyroidism or a remaining 5th gland in the cervical region was suspected. In all 22 patients serum calcium, as well as alkaline phosphatase levels returned to normal and the clinical signs of hyperparathyroidism disappeared.

Adult↗
PubMed1991

Neurotoxic effects of chloroquine in vitro.

In order to investigate chloroquine retinopathy, the effect of chloroquine on the viability and differentiation of primary cell cultures of embryonic chick neuronal retina, retinal pigment epithelium (RPE), brain and meninges were investigated. The sensitivity of the cells, measured as reduction of viability, showed the following order: RPE greater than brain greater than meninges greater than neuronal retina. The human serum chloroquine concentration range which leads to ocular damage in vivo was identical to the concentration range in the culture medium which affected RPE viability. In addition, the differentiation of nerve cells in brain cell cultures was affected at much lower chloroquine concentrations than astroglia cells or nerve cells in neuronal retina cell cultures. Some possible mechanisms for chloroquine retinopathy were assessed.

Animals↗