The type 1 receptor (CD120a) is the high-affinity receptor for soluble tumor necrosis factor

Tumor necrosis factor (TNF) can induce a variety of cellular responses at low picomolar concentrations. This is in apparent conflict with the published dissociation constants for TNF binding to TNF receptors in the order of 100-500 pM. To elucidate the mechanisms underlying the outstanding cellular sensitivity to TNF, we determined the binding characteristics of TNF to both human TNF receptors at 37 degrees C. Calculation of the dissociation constant (Kd) from the association and dissociation rate constants determined at 37 degrees C revealed a remarkable high affinity for TNF binding to the 60-kDa TNF type 1 receptor (TNF-R1; Kd = 1.9 x 10(-11) M) and a significantly lower affinity for the 80-kDa TNF type 2 receptor (TNF-R2; Kd = 4.2 x 10(-10) M). The high affinity determined for TNF-R1 is mainly caused by the marked stability of ligand-receptor complexes in contrast to the transient interaction of soluble TNF with TNF-R2. These data can readily explain the predominant role of TNF-R1 in induction of cellular responses by soluble TNF and suggest the stability of the TNF-TNF receptor complexes as a rationale for their differential signaling capability. In accordance with this reasoning, the lower signaling capability of homotrimeric lymphotoxin, compared with TNF, correlates with a lower stability of the lymphotoxin-TNF-R1 complex at 37 degrees C.

[Fate of the calcium-dense proximal fragment in scaphoid fracture]

A cohort study with retrolective and prolective collection of data was carried out 49 of 99 patients with scaphoid fractures, initially treated by plaster cast immobilization and having developed a proximal fragment with increased bone density were studied. More than half of these patients had a good or excellent result according to the modified score of Green and O'Brien 29 of 49 proximal fragments with increased bone density returned to normal density: 45 of 49 showed bony union, and 35 of 49 showed no signs of posttraumatic arthrosis. The appearance of stripes with increased bone density in plain X-rays indicated a problem in the process of fracture healing; the clinical interpretation, however, was difficult. Four patients were treated by percutaneous canulated screw (Streli). These fractures showed bony union, the fragment with increased bone density returned to normal in three of four patients. All of these patients had some remaining clinical problems.

[Risk assessment in ovarian hyperstimulation syndrome (OHS) using the machine learning system (Decision Master) in 155 in-vitro fertilisations and embryo-transfer (IVF/ET) cycles with a long stimulation protocol]

In 155 selected IVF/ET cycles stimulated with the long protocol 25 cycles with severe OHS are included which turned up later on (purposely overrepresented). An inductive machine learning program is described both in informatics and medical essentials. It is tested whether there exists an algorithm for ruling out the above-mentioned complication in the follicular phase of the same cycle already. By cross validation 89% of the OHS could be predicted and proven by practical rules using hormone and ultrasound values to avoid similar events in ongoing or further cycles.

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.

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.

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.

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.

[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.

[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.

[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.

[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.

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.

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.

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.

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.

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.