ZEB1-repressed microRNAs inhibit autocrine signaling that promotes vascular mimicry of breast cancer cells.

During normal tumor growth and in response to some therapies, tumor cells experience acute or chronic deprivation of nutrients and oxygen and induce tumor vascularization. While this occurs predominately through sprouting angiogenesis, tumor cells have also been shown to directly contribute to vessel formation through vascular mimicry (VM) and/or endothelial transdifferentiation. The extrinsic and intrinsic mechanisms underlying tumor cell adoption of endothelial phenotypes, however, are not well understood. Here we show that serum withdrawal induces mesenchymal breast cancer cells to undergo VM and that knockdown of the epithelial-to-mesenchymal transition (EMT) regulator, Zinc finger E-box binding homeobox 1 (ZEB1), or overexpression of the ZEB1-repressed microRNAs (miRNAs), miR-200c, miR-183, miR-96 and miR-182 inhibits this process. We find that secreted proteins Fibronectin 1 (FN1) and serine protease inhibitor (serpin) family E member 2 (SERPINE2) are essential for VM in this system. These secreted factors are upregulated in mesenchymal cells in response to serum withdrawal, and overexpression of VM-inhibiting miRNAs abrogates this upregulation. Intriguingly, the receptors for these secreted proteins, low-density lipoprotein receptor-related protein 1 (LRP1) and Integrin beta 1 (ITGB1), are also targets of the VM-inhibiting miRNAs, suggesting that autocrine signaling stimulating VM is regulated by ZEB1-repressed miRNA clusters. Together, these data provide mechanistic insight into the regulation of VM and suggest that miRNAs repressed during EMT, in addition to suppressing migratory and stem-like properties of tumor cells, also inhibit endothelial phenotypes of breast cancer cells adopted in response to a nutrient-deficient microenvironment.

Impact of donor type on outcome of bone marrow transplantation for Wiskott-Aldrich syndrome: collaborative study of the International Bone Marrow Transplant Registry and the National Marrow Donor Program.

Human leukocyte antigen (HLA)-identical sibling bone marrow transplantation is an effective treatment for Wiskott-Aldrich syndrome. However, most children with this disease lack such donors and many patients receive transplants from alternative donors. This study compared outcomes of HLA-identical sibling, other related donor, and unrelated donor transplantation for Wiskott-Aldrich syndrome. The outcome of 170 transplantations for Wiskott-Aldrich syndrome, from 1968 to 1996, reported to the International Bone Marrow Transplant Registry and/or National Marrow Donor Program were assessed. Fifty-five were from HLA-identical sibling donors, 48 from other relatives, and 67 from unrelated donors. Multivariate proportional hazards regression was used to compare outcome by donor type and identify other prognostic factors. Most transplant recipients were younger than 5 years (79%), had a pretransplantation performance score greater than or equal to 90% (63%), received pretransplantation preparative regimens without radiation (82%), and had non-T-cell-depleted grafts (77%). Eighty percent received their transplant after 1986. The 5-year probability of survival (95% confidence interval) for all subjects was 70% (63%-77%). Probabilities differed by donor type: 87% (74%-93%) with HLA-identical sibling donors, 52% (37%-65%) with other related donors, and 71% (58%-80%) with unrelated donors (P =.0006). Multivariate analysis indicated significantly lower survival using related donors other than HLA-identical siblings (P =.0004) or unrelated donors in boys older than 5 years (P =.0001), compared to HLA-identical sibling transplants. Boys receiving an unrelated donor transplant before age 5 had survivals similar to those receiving HLA-identical sibling transplants. The best transplantation outcomes in Wiskott-Aldrich syndrome are achieved with HLA-identical sibling donors. Equivalent survivals are possible with unrelated donors in young children.

T-cell depletion of bone marrow transplants for leukemia from donors other than HLA-identical siblings: advantage of T-cell antibodies with narrow specificities.

T-cell depletion of donor marrow decreases graft-versus-host disease resulting from transplants from unrelated and human leukocyte antigen (HLA)-mismatched related donors. However, there are diverse strategies for T-cell-depleted transplantation, and it is uncertain whether any improve leukemia-free survival (LFS). To compare strategies for T-cell-depleted alternative donor transplants and to compare T-cell depleted with non-T-cell-depleted transplants, we studied 870 patients with leukemia who received T-cell-depleted transplants from unrelated or HLA-mismatched related donors from 1982 to 1994. Outcomes were compared with those of 998 non-T-cell-depleted transplants. We compared LFS using different strategies for T-cell-depleted transplantation considering T-cell depletion technique, intensity of pretransplant conditioning, and posttransplant immune suppression using proportional hazards regression to adjust for other prognostic variables. Five categories of T-cell depletion techniques were considered: narrow-specificity antibodies, broad-specificity antibodies, Campath antibodies, elutriation, and lectins. Strategies resulting in similar LFS were pooled to compare T-cell-depleted with non-T-cell-depleted transplants. Recipients of transplants T-cell depleted by narrow-specificity antibodies had lower treatment failure risk (higher LFS) than recipients of transplants T-cell depleted by other techniques. Compared with non-T-cell-depleted transplants (5-year probability +/- 95% confidence interval [CI] of LFS, 31% +/- 4%), 5-year LFS was 29% +/- 5% (P = NS) after transplants T-cell depleted by narrow-specificity antibodies and 16% +/- 4% (P <.0001) after transplants T-cell depleted by other techniques. After alternative donor transplantation, T-cell depletion of donor marrow by narrow-specificity antibodies resulted in LFS rates that were higher than those for transplants T-cell depleted using other techniques but similar to those for non-T-cell-depleted transplants. (Blood. 2000;95:3996-4003)

Factors correlated with progression-free survival after high-dose chemotherapy and hematopoietic stem cell transplantation for metastatic breast cancer.

CONTEXT: Women with breast cancer are the most frequent recipients of high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (autotransplants) in North America. Despite widespread use, controversy exists about the benefits of and appropriate patients for this therapy. OBJECTIVE: To determine factors associated with disease progression or death after autotransplantation in women with metastatic breast cancer. DESIGN: Analysis of data collected retrospectively (January 1989 to 1992) and prospectively (1992 through January 1995) for the Autologous Blood and Marrow Transplant Registry. SETTING: Sixty-three hospitals in North America, Brazil, and Russia. PARTICIPANTS: A total of 1188 consecutive women aged 18 to 70 years receiving autotransplants for metastatic or locally recurrent breast cancer, with a median follow-up of 291/2 months. MAIN OUTCOME MEASURE: Time to treatment failure (disease progression, disease recurrence, or death) after autotransplantation. RESULTS: Factors associated with significantly (P<.05) increased risk of treatment failure in a Cox multivariate analysis included age older than 45 years (relative hazard, 1.17; 95% confidence interval [CI], 1.02-1.33), Karnofsky performance score less than 90% (1.27; 95% CI, 1.07-1.51), absence of hormone receptors (1.31; 95% CI, 1.15-1.51), prior use of adjuvant chemotherapy (1.31; 95% CI, 1.10-1.56), initial disease-free survival interval after adjuvant treatment of no more than 18 months (1.99; 95% CI, 1.62-2.43), metastases in the liver (1.47; 95% CI, 1.20-1.80) or central nervous system (1.56; 95% CI, 0.99-2.46 [approaches significance]) vs soft tissue, bone, or lung, 3 or more sites of metastatic disease (1.32; 95% CI, 1.13-1.54), and incomplete response vs complete response to standard-dose chemotherapy (1.65; 95% CI, 1.36-1.99). Receiving tamoxifen posttransplantation was associated with a reduced risk of treatment failure in women with hormone receptor-positive tumors (relative hazard, 0.60; 95% CI, 0.47-0.87). Women with no risk factors (n = 38) had a 3-year probability of progression-free survival of 43% (95% CI, 27%-61 %) vs 4% (95% CI, 2%-8%) for women with more than 3 risk factors (n = 343). CONCLUSION: These data indicate that some women are unlikely to benefit from autotransplantation and should receive this treatment only after being provided with prognostic information and in the context of clinical trials attempting to improve outcome.

Recurrent and de novo glomerular disease after renal transplantation: a report from Renal Allograft Disease Registry (RADR).

INTRODUCTION: Short-term and long-term results of renal transplantation have improved over the past 15 years. However, there has been no change in the prevalence of recurrent and de novo diseases. A retrospective study was initiated through the Renal Allograft Disease Registry, to evaluate the prevalence and impact of recurrent and de novo diseases after transplantation. MATERIALS AND METHODS: From October 1987 to December 1996, a total of 4913 renal transplants were performed on adults at the Medical College of Wisconsin, University of Cincinnati, University of California at San Francisco, University of Louisville, University of Washington, Seattle, and Washington University School of Medicine. The patients were followed for a minimum of 1 year. A total of 167 (3.4%) cases of recurrent and de novo disease were diagnosed by renal biopsy. These patients were compared with other patients who did not have recurrent and de novo disease (n=4746). There were more men (67.7% vs. 59.8%, P<0.035) and a higher number of re-transplants (17% vs. 11.5%, P<0.005) in the recurrent and de novo disease group. There was no difference in the rate of recurrent and de novo disease according to the transplant type (living related donor vs. cadaver, P=NS). Other demographic findings were not significantly different. Common forms of glomerulonephritis seen were focal segmental glomerulosclerosis (FSGS), 57; immunoglobulin A nephritis, 22; membranoproliferative glomerulonephritis (GN), 18; and membranous nephropathy, 16. Other diagnoses include: diabetic nephropathy, 19; immune complex GN, 12; crescentic GN (vasculitis), 6; hemolytic uremic syndrome-thrombotic thrombocytopenic purpura (HUS/TTP), 8; systemic lupus erythematosus, 3; Anti-glomerular basement membrane disease, 2; oxalosis, 2; and miscellaneous, 2. The diagnosis of recurrent and de novo disease was made after a mean period of 678 days after the transplant. During the follow-up period, there were significantly more graft failures in the recurrent disease group, 55% vs. 25%, P<0.001. The actuarial 1-, 2-, 3-, 4, and 5-year kidney survival rates for patients with recurrent and de novo disease was 86.5%, 78.5%, 65%, 47.7%, and 39.8%. The corresponding survival rates for patients without recurrent and de novo disease were 85.2%, 81.2%, 76.5%, 72%, and 67.6%, respectively (Log-rank test, P<0.0001). The median kidney survival rate for patients with and without recurrent and de novo disease was 1360 vs. 3382 days (P<0.0001). Multivariate analysis using the Cox proportional hazard model for graft failure was performed to identify various risk factors. Cadaveric transplants, prolonged cold ischemia time, elevated panel reactive antibody, and recurrent disease were identified as risk factors for allograft failure. The relative risk (95% confidence interval) for graft failure because of recurrent and de novo disease was 1.9 (1.57-2.40), P<0.0001. The relative risk for graft failure because of posttransplant FSGS was 2.25 (1.6-3.1), P<0.0001, for membranoprolifera. tive glomerulonephritis was 2.37 (1.3-4.2), P<0.003, and for HUS/TTP was 5.36 (2.2-12.9), P<0.0002. There was higher graft failure (64.9%) and shorter half-life (1244 days) in patients with recurrent FSGS. CONCLUSION: In conclusion, recurrent and de novo disease are associated with poorer long-term survival, and the relative risk of allograft loss is double. Significant impact on graft survival was seen with recurrent and de novo FSGS, membranoproliferative glomerulonephritis, and HUS/TTP.

IA in Kenyon cells of the mushroom body of honeybees resembles shaker currents: kinetics, modulation by K+, and simulation.

Cultured Kenyon cells from the mushroom body of the honeybee, Apis mellifera, show a voltage-gated, fast transient K+ current that is sensitive to 4-aminopyridine, an A current. The kinetic properties of this A current and its modulation by extracellular K+ ions were investigated in vitro with the whole cell patch-clamp technique. The A current was isolated from other voltage-gated currents either pharmacologically or with suitable voltage-clamp protocols. Hodgkin- and Huxley-style mathematical equations were used for the description of this current and for the simulation of action potentials in a Kenyon cell model. Activation and inactivation of the A current are fast and voltage dependent with time constants of 0.4 +/- 0.1 ms (means +/- SE) at +45 mV and 3.0 +/- 1.6 ms at +45 mV, respectively. The pronounced voltage dependence of the inactivation kinetics indicates that at least a part of this current of the honeybee Kenyon cells is a shaker-like current. Deactivation and recovery from inactivation also show voltage dependency. The time constant of deactivation has a value of 0.4 +/- 0.1 ms at -75 mV. Recovery from inactivation needs a double-exponential function to be fitted adequately; the resulting time constants are 18 +/- 3.1 ms for the fast and 745 +/- 107 ms for the slow process at -75 mV. Half-maximal activation of the A current occurs at -0.7 +/- 2.9 mV, and half-maximal inactivation occurs at -54.7 +/- 2.4 mV. An increase in the extracellular K+ concentration increases the conductance and accelerates the recovery from inactivation of the A current, affecting the slow but not the fast time constant. With respect to these modulations the current under investigation resembles some of the shaker-like currents. The data of the A current were incorporated into a reduced computational model of the voltage-gated currents of Kenyon cells. In addition, the model contained a delayed rectifier K+ current, a Na+ current, and a leakage current. The model is able to generate an action potential on current injection. The model predicts that the A current causes repolarization of the action potential but not a delay in the initiation of the action potential. It further predicts that the activation of the delayed rectifier K+ current is too slow to contribute markedly to repolarization during a single action potential. Because of its fast activation, the A current reduces the amplitude of the net depolarizing current and thus reduces the peak amplitude and the duration of the action potential.

Modeling random effects for censored data by a multivariate normal regression model.

A normal distribution regression model with a frailty-like factor to account for statistical dependence between the observed survival times is introduced. This model, as opposed to standard hazard-based frailty models, has survival times that, conditional on the shared random effect, have an accelerated failure time representation. The dependence properties of this model are discussed and maximum likelihood estimation of the model's parameters is considered. A number of examples are considered to illustrate the approach. The estimated degree of dependence is comparable to other models, but the present approach has the advantage that the interpretation of the random effect is simpler than in the frailty model.

Prognostic value of intraoperative blood flow measurements in vascular access surgery.

BACKGROUND: The purpose of this study was to correlate intraoperative blood flow measurements with outcome in vascular access surgery. METHODS: In 303 patients, 389 vascular access operations were performed. Intraoperative blood flow measurements were made immediately following construction of 227 autogenous and 162 prosthetic arteriovenous fistulas (AVFs) using a handheld flowprobe. Blood flow measurements were stratified by demographic variables such as age, race, sex, and presence of diabetes and were correlated with primary and secondary (assisted) patency. Statistical methods included life-table analysis and Cox proportional hazards model. RESULTS: Blood flow increased progressively from distal to proximal access sites and was not significantly affected by age, race, sex, or presence of diabetes. Autogenous AVFs with flow rates at or below 320 mL/min and polytetrafluoroethylene (PTFE) grafts with flow rates at or below 400 mL/min had significantly worse primary and secondary patency rates compared to their higher flow counterparts at all sites. Using hazard analysis flow rate was the single most important determinant of primary and secondary patency. PTFE grafts with flow rates at or below 400 mL/min also required more interventions (1.58 per patient-year) and failed sooner (median time, 0.5 +/- 4.7 months) than grafts with flow rates above 400 mL/min (1.08 interventions per patient-year; P = .03; median time, 1.6 +/- 5.0 months; P = .003). CONCLUSIONS: Intraoperative measurements of access blood flow provide objective, reliable data that correlate with outcome. Routine use of this technology might lead to more efficient management of patients undergoing hemodialysis access surgery.

Successful unrelated marrow transplantation for patients over the age of 40 with chronic myelogenous leukemia.

Some older patients (> or =40 years) with chronic myelogenous leukemia (CML) who lack human leukocyte antigen (HLA)-identical sibling donors are not offered unrelated marrow transplantation because of concerns over excessive regimen-related toxicity, in particular due to graft-vs.-host disease (GVHD). The purpose of this study was to determine the efficacy and toxicity of unrelated marrow transplantation in older CML patients using a regimen designed to minimize the severity of GVHD. Thirty-one consecutive patients over the age of 40 with CML received unrelated marrow transplants between January 1988 and June 1997. Twenty-one patients were transplanted in chronic phase while ten were transplanted in the accelerated phase of their disease. Fifteen patients received transplants from phenotypically matched donors while 16 received marrow grafts from donors who were mismatched at one HLA locus. GVHD prophylaxis consisted of ex vivo T cell depletion of the donor marrow graft plus posttransplant cyclosporine administration. Durable engraftment was achieved in 29 of 31 patients (94%). The probability of developing grades II-IV or severe grades III-IV acute GVHD was 39.2 and 7.1%, respectively. There was no difference in the incidence of grades II-IV acute GVHD between patients transplanted with marrow grafts from phenotypically matched (38.1%) vs. those transplanted from mismatched unrelated donors (40%, p = 0.99). The 2-year probability of relapse for the entire population was 29.4%. Relapse was significantly higher for patients transplanted in accelerated phase (60%) than for those in chronic phase (13.8%, p = 0.027). The 2-year probability of overall survival and disease-free survival for the entire cohort was 56 and 45%, respectively. There was no significant difference in survival or disease-free survival for patients receiving phenotypically matched vs. mismatched marrow grafts. Immunological reconstitution for this cohort was compared with a younger (<40 years) patient population that had been similarly transplanted over the same time period. Immune function as assessed by total T cell, B cell, NK cell, and T cell subset reconstitution posttransplant was quantitatively equivalent in the two groups with most parameters normalizing within 18 months of transplant. We conclude that CML patients over the age of 40 who have either phenotypically matched or one antigen-mismatched unrelated donors can successfully undergo allogeneic marrow transplantation. T cell depletion of the marrow graft may be advantageous in these older patients by reducing GVHD severity, particularly in those patients transplanted with HLA-disparate marrow grafts.

Neonatal cord blood leptin: its relationship to birth weight, body mass index, maternal diabetes, and steroids.

Leptin is a 16-kD protein encoded by the ob/ob (obesity) gene. In rodents it plays a role in obesity, diabetes, fertility, and neuroendocrine function. In humans serum concentrations of leptin correlate with total body fat in both adults and children. We measured cord blood leptin in 186 neonates that included 82 appropriate for gestational age (AGA), 47 large for gestational age (LGA), 20 infants of diabetic mothers, 52 preterm infants, and 15 intrauterine growth-retarded (IUGR) infants. There were 16 pairs of twins. The mothers of 17 preterm infants were treated with steroids before delivery. Leptin (mean +/- SD) concentration in term, AGA infants (39.4 +/- 1.1 wk) with birth weight (BW) of 3.2 +/- 0.3 kg, body mass index (BMI) of 12.6 +/- 1.1 was 4.01 +/- 3.5 ng/mL. BW correlated with cord leptin (p = 0.002) in a multivariate analysis controlling for potential confounders. Both LGA infants and infants of diabetic mothers had higher cord leptin concentration 7.3 +/- 3.8 and 6.1 +/- 4.8 ng/mL, respectively, compared with AGA infants (p < 0.05). Preterm infants had a mean leptin level of 1.8 +/- 0.97 ng/mL and a 3-fold elevation was seen if mothers received steroids antenatally (p = 0.006). IUGR infants had increased leptin (6.5 +/- 3.9 ng/mL, p = 0.03). Concerning the twin pairs, the smaller had a higher leptin level compared with larger twin (4.1 +/- 9.51 versus 2.8 +/- 5.14, p = NS). Neonatal cord leptin concentrations correlate well with BW and BMI. No gender differences were found in cord blood leptin. Maternal obesity had no effect on cord leptin, whereas exogenous maternal steroids increased neonatal leptin concentrations.

High-dose chemotherapy with autologous hematopoietic stem-cell support for breast cancer in North America.

PURPOSE: To identify trends in high-dose therapy with autologous hematopoietic stem-cell support (autotransplants) for breast cancer (1989 to 1995). PATIENTS AND METHODS: Analysis of patients who received autotransplants and were reported to the Autologous Blood and Marrow Transplant Registry. Between January 1, 1989 and June 30, 1995, 19,291 autotransplants were reviewed; 5,886 were for breast cancer. Main outcomes were progression-free survival (PFS) and survival. RESULTS: Between 1989 and 1995, autotransplants for breast cancer increased sixfold. After 1992, breast cancer was the most common indication for autotransplant. Significant trends included increasing use for locally advanced rather than metastatic disease (P < .00001) and use of blood-derived rather than marrow-derived stem cells (P < .00001). One-hundred-day mortality decreased from 22% to 5% (P < .0001). Three-year PFS probabilities were 65% (95% confidence intervals [Cls], 59 to 71) for stage 2 disease, and 60% (95% Cl, 53 to 67) for stage 3 disease. In metastatic breast cancer, 3-year probabilities of PFS were 7% (95% Cl, 4 to 10) for women with no response to conventional dose chemotherapy; 13% (95% Cl, 9 to 17) for those with partial response; and 32% (95% Cl, 27 to 37) for those with complete response. Eleven percent of women with stage 2/3 disease and less than 1% of those with stage 4 disease participated in national cooperative group randomized trials. CONCLUSION: Autotransplants increasingly are used to treat breast cancer. One-hundred-day mortality has decreased substantially. Three-year survival is better in women with earlier stage disease and in those who respond to pretransplant chemotherapy.

Odorant intensity as a determinant for olfactory conditioning in honeybees: roles in discrimination, overshadowing and memory consolidation.

Stimulus intensity is an important determinant for perception, learning and behaviour. We studied the effects of odorant concentration on classical conditioning involving odorants and odorant-mechanosensory compounds using the proboscis-extension reflex in the honeybee. Our results show that high concentrations of odorant (a) support better discrimination in a feature-positive task using rewarded odorant-mechanosensory compounds versus unrewarded mechanosensory stimuli, (b) have a stronger capacity to overshadow learning of a simultaneously trained mechanosensory stimulus, and (c) induce better memory consolidation. Furthermore, honeybees were trained discriminatively to two different concentrations of one odorant. Honeybees are not able to solve this task when presented with rewarded low versus unrewarded high concentrations. Taken together, our results suggest that high concentrations of odorant support stronger associations (are more 'salient') than low concentrations. Our results, however, do not indicate that honeybees can treat two different concentrations of one odorant as qualitatively different stimuli. These findings fill a gap in what is known about honeybee olfactory learning and are a first step in relating behaviour to recent advances in the physiological analysis of coding for odorant concentration in honeybees.

Report from the International Bone Marrow Transplant Registry and Autologous Blood and Marrow Transplant Registry - North America.

Allogeneic and autologous bone marrow and blood cell transplants are increasingly used treatments for cancer and disorders of bone marrow and immune function. This is largely due to use of autotransplants to treat common diseases such as breast cancer. The use of blood cells alone for autotransplants was also a significant change in the past 5 years. The IBMTR and ABMTR continue to provide a unique resource for studying outcomes and trends in allogeneic and autologous bone marrow and blood cell transplants.

Characterization of the membrane-associated GTPase activity: effects of chemotactic factors and toxins.

Membranes prepared from rabbit neutrophils exhibit GTPase activity which can be stimulated by the chemotactic factor fMet-Leu-Phe. The maximum contribution of the ATPase activities to the basal and the fMet-Leu-Phe-stimulated GTPase activities are less than 20% and 9%, respectively. The basal GTPase activity has a Vmax = 34.2 +/- 1.3 (pmol/mg protein, min) and a Km = 0.39 +/- 0.03 microM; and the fMet-Leu-Phe-stimulated has a Vmax = 52.3 +/- 2.5 (pmol/mg protein, min), and a Km = 0.29 +/- 0.02 microM. The GTPase activity can be stimulated by fMet-Leu-Phe and leukotriene B4. Unlike these two chemotactic factors, concanavalin A does not stimulate this GTPase activity. In addition, the rise in intracellular concentration of free calcium produced by concanavalin A is not inhibited by pertussis toxin treatment. Both the basal and stimulated GTPase activities are affected by pertussis toxin, cholera toxin and N-ethylmaleimide.

Treatment of rabbit neutrophils with phorbol esters results in increased ADP-ribosylation catalyzed by pertussis toxin and inhibition of the GTPase stimulated by fMet-Leu-Phe.

The effects of pretreatment of rabbit neutrophils with phorbol 12-myristate 13-acetate on the ability of pertussis toxin to catalyze ADP-ribosylation and of fMet-Leu-Phe to activate a high-affinity GTPase in these cell homogenates were examined. The addition of phorbol 12-myristate 13-acetate, but not 4 alpha-phorbol 12,13-didecanoate, to intact cells was found to stimulate by more than 100% the pertussis toxin-dependent ribosylation of a 41 kDa protein (either the alpha-subunit of the 'inhibitory' guanine nucleotide-binding protein N or a closely analogous protein) and to inhibit by more than 60% the activation by fMet-Leu-Phe of the GTPase of the neutrophil homogenates. The addition of fMet-Leu-Phe to intact cells increases the ADP-ribosylation catalyzed by pertussis toxin of the 41 kDa protein. On the other hand, the exposure of neutrophil homogenates to fMet-Leu-Phe results in a decreased level of ADP-ribosylation. This decreased ribosylation reflects a dissociation of the GTP-binding protein oligomer that is not followed by association, possibly because of the release of the alpha-subunit into the suspending media. The implications of these results for the understanding of the mechanism of inhibition of cell responsiveness by phorbol esters and the heterologous desensitization phenomenon are discussed. Prominent among these are the possibilities that (i) the rate of dissociation of the Ni oligomer is affected by the degree of its phosphorylation by protein kinase C, and/or (ii) the dissociated phosphorylated alpha-subunit (the 41 kDa protein) is functionally less active than its dephosphorylated couterpart.

[Transanal endoscopic surgery of the rectum - testing a new method in animal experiments]. / Die transanale endoskopische Rektumoperation - Erprobung einer neuen Methode im Tierversuch.

Surgery of the lower third of the rectum can be done without difficulty through the anus using an endoscopical approach. Polyps or tumors located in the upper two thirds of the rectum can be removed using the Mason or Kraske procedure, or by the transabdominal approach. A new endoscopic technique has been developed with the aim, to allow surgery in the whole rectum through the anus. The rectum is being dilated by mechanical means and air insufflation. An oblique angle stereoscopic endoscope as well as modified surgical instruments are used. In animals 47 excisions of mucosa were done, and the incisions were closed by continuous suture. Application of this technique in a clinical setting is planned.