Mitochondrial cysteine synthase complex regulates O-acetylserine biosynthesis in plants

Cysteine synthesis is catalyzed by serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL) in the cytosol, plastids, and mitochondria of plants. Biochemical analyses of recombinant plant SAT and OAS-TL indicate that the reversible association of the proteins in the cysteine synthase complex (CSC) controls cellular sulfur homeostasis. However, the relevance of CSC formation in each compartment for flux control of cysteine synthesis remains controversial. Here, we demonstrate the interaction between mitochondrial SAT3 and OAS-TL C in planta by FRET and establish the role of the mitochondrial CSC in the regulation of cysteine synthesis. NMR spectroscopy of isolated mitochondria from WT, serat2;2, and oastl-C plants showed the SAT-dependent export of OAS. The presence of cysteine resulted in reduced OAS export in mitochondria of oastl-C mutants but not in WT mitochondria. This is in agreement with the stronger in vitro feedback inhibition of free SAT by cysteine compared with CSC-bound SAT and explains the high OAS export rate of WT mitochondria in the presence of cysteine. The predominant role of mitochondrial OAS synthesis was validated in planta by feeding [(3)H]serine to the WT and loss-of-function mutants for OAS-TLs in the cytosol, plastids, and mitochondria. On the basis of these results, we propose a new model in which the mitochondrial CSC acts as a sensor that regulates the level of SAT activity in response to sulfur supply and cysteine demand.

Bi-specific aptamers mediating tumor cell lysis

Antibody-dependent cellular cytotoxicity plays a pivotal role in antibody-based tumor therapies and is based on the recruitment of natural killer cells to antibody-bound tumor cells via binding of the Fcγ receptor III (CD16). Here we describe the generation of chimeric DNA aptamers that simultaneously bind to CD16α and c-Met, a receptor that is overexpressed in many tumors. By application of the systematic evolution of ligands by exponential enrichment (SELEX) method, CD16α specific DNA aptamers were isolated that bound with high specificity and affinity (91 pm-195 nm) to their respective recombinant and cellularly expressed target proteins. Two optimized CD16α specific aptamers were coupled to each of two c-Met specific aptamers using different linkers. Bi-specific aptamers retained suitable binding properties and displayed simultaneous binding to both antigens. Moreover, they mediated cellular cytotoxicity dependent on aptamer and effector cell concentration. Displacement of a bi-specific aptamer from CD16α by competing antibody 3G8 reduced cytotoxicity and confirmed the proposed mode of action. These results represent the first gain of a tumor-effective function of two distinct oligonucleotides by linkage into a bi-specific aptamer mediating cellular cytotoxicity.

Diagnosis of penicillin allergy by means of Phadebas RAST penicilloyl G and V and skin tests

Fifty patients with suspected allergy to penicillin were tested. Skin tests were done with Na-penicillin G and penicilloyl-polylysin. Specific IgE antibody assays were done with penicilloyl G and V conjugates by means of RAST. The overall agreement between skin test and RAST results was 87%, borderline cases not included. In one case, skin tests were positive to penicillamine only, while RAST for penicilloyl G and V both proved to be positive. One case of penicillin allergy could be diagnosed in vitro post mortem only. Two cases of Hoigné syndrome showed no evidence of allergy. Patterns of skin manifestations varied but urticaria was the most commonly seen feature. Twenty patients without adverse reactions to penicillin treatment and seven patients who had not received penicillin over the last 10 years served as controls. None of them were positive in either skin tests of RAST. Two or our twenty control patients developed penicillin allergy during the study. Both showed positive RAST results.

Influence of dialysable transfer factor on IgE concentrations in patients with atopic dermatitis

Dialysable transfer factor (TF) was given in 10 paediatric patients with severe atopic dermatitis (AD). Ten patients with AD, matched for age and severity of disease, served as controls. Prior to the therapy with TF and at weekly intervals thereafter, T- and B-cells in the blood, PHA-stimulation, total IgE and specific IgG antibodies to inhalant and food antigens were determined. Therapy with TF was followed by IgE depression in 8/10 patients and was most pronounced in three patients with initially high levels. Some decrease of IgE levels was seen in four controls also, none of them, however, fell to normal levels as was seen in two of the treated patients. Specific IgE levels decreased slightly, but always remained within the pathological range. T-cell counts in the blood increased in 2/10 cases as well as PHA-stimulation, B-cells counts remained within normal limits. Clinical improvement was seen in one patient, five improved slightly and four remained unchanged. Our results indicate, that transfer factor can lower total IgE levels in cases with atopic dermatitis. The effect is most marked in patients with high total IgE levels. Skin involvement, however, does not closely follow in vitro findings.

[Lupus vulgaris, metastasized carcinoma in lupus and epithelioid cell lymph node tuberculosis]

In a patient the simultaneous occurrence of lupus vulgaris, lupus carcinoma, metastatic to the regional lymphnodes and glandular tuberculosis is reported.

IgE antibodies to bee venom, phospholipase A, melittin and wasp venom

Specific IgE antibodies against bee venom, phospholipase A, melittin and wasp venom have been examined in fifty patients with an unusually severe reaction after bee or wasp sting. Two thirds of the bee venom-sensitive patients also have detectable IgE antibodies to wasp venom. More than 50% of the wasp venom-sensitive patients are also allergic to bee venom. Phospholipase A and melittin IgE antibodies were found, respectively, in two thirds and one third of the bee venom-sensitive cases. Specific IgE antibody determinations by the Radioallergosorbent test play an essential role in the diagnostic work. After a reaction to hymenoptera stings both bee and wasp venom tests are necessary due to the high incidence of a false or incomplete identification of the stinging insect. Melittin, known for its potent pharmacological activity and possibly responsible for most of the side effects in bee venom immunotherapy, can probably not be excluded from therapeutic venom preparations since IgE antibodies to the melittin preparation were detected in one third of the cases.

[On the radio-surgery of the carcinoma of the tongue (n = 1,000) (author's transl)]

In the period 1931 to 1976 1,116 patients were admitted to our department--1,000 were treatable. The 5 year survival rate is 26.7% out of 975 cases with follow-up. There is a marked difference between the regions of the corpus and the radix linguae which present with different symptoms and--in relation to these--have a very different prognosis. The Ca linguae and sublinguale are without symptoms--after treatment--in 29.15%, the Ca radicis linguae in 10.5% only. The method of choice was in case of circumscribed invasion radio-surgery, in case of Radix Ca or diffusion or involvement of fixated lymphnodes irradiation with external beams: Radium, Cobalt, Betatron. 20 years ago, Wasserburger, the late leader of our departement, published the results of his investigations on data of 628 patients with Ca of the tongue. The good results which are due to a methodical approach and meticulous treatment were not equalled by another method, neither irradiation alone nor surgery. To preserve the unique homogeneity of this material we stuck to this therapy which consists in the coagulation of the tumor, interstitial implants of radium-needles in the layers adjacent to the electrocoagulation and in external radiation of the regional lymphnodes and additional chemotherapy if indicated. On january, 21st., 1976, the thousandst patient with Ca of the tongue was admitted to our departement to be treated and so continues the chain of patients which were extensively documented and are followed up in coordinative work with the ENT departement in our hospital. In summary there were 1,116 cases, 116 were too progredient to be treated.

[On the radiotherapy of the carcinoma of the tonsils (author's transl)]

In the period 1932 to 1975 469 patients were admitted with a malignoma of the tonsils. 74,9% were stage T3. Nearly 50% showed up with involvement of fixated and suspicious lymphnodes. The relation men to women was 80:20. The highest incidence was found in the age group 61-70 a. The patients were treated using Radium: interstitial implants and external radiation, later Cobalt sources and the Betatron. The over-all 5 year survival rate is 21.6% for carcinomas and 32% for sarcomas. In the case histories there are predominantly late ones because difficulties in swallowing are neglected for a long time. The prognosis for cases stage T3 is rather bad. Considering the literature our material is the greatest out of a single department.