Strongly reducing magnesium(0) complexes.

A complex of a metal in its zero oxidation state can be considered a stabilized, but highly reactive, form of a single metal atom. Such complexes are common for the more noble transition metals. Although rare examples are known for electronegative late-main-group p-block metals or semimetals1-6, it is a challenge to isolate early-main-group s-block metals in their zero oxidation state7-11. This is directly related to their very low electronegativity and strong tendency to oxidize. Here we present examples of zero-oxidation-state magnesium (that is, magnesium(0)) complexes that are stabilized by superbulky, monoanionic, ß-diketiminate ligands. Whereas the reactivity of an organomagnesium compound is typically defined by the nucleophilicity of its organic groups and the electrophilicity of Mg2+ cations, the Mg0 complexes reported here feature electron-rich Mg centres that are nucleophilic and strongly reducing. The latter property is exemplified by the ability to reduce Na+ to Na0. We also present a complex with a linear Mg3 core that formally could be described as a MgI-Mg0-MgI unit. Such multinuclear mixed-valence Mgn clusters are discussed as fleeting intermediates during the early stages of Grignard reagent formation. Their remarkably strong reducing power implies a rich reactivity and application as specialized reducing agents.

Dinitrogen complexation and reduction at low-valent calcium.

Here we report that attempted preparation of low-valent CaI complexes in the form of LCa-CaL (where L is a bulky ß-diketiminate ligand) under dinitrogen (N2) atmosphere led to isolation of LCa(N2)CaL, which was characterized crystallographically. The N2 2- anion in this complex reacted in most cases as a very potent two-electron donor. Therefore, LCa(N2)CaL acts as a synthon for the low-valent CaI complex LCa-CaL, which was the target of our studies. The N2 2- anion could also be protonated to diazene (N2H2) that disproportionated to hydrazine and N2 The role of Ca d orbitals for N2 activation is discussed.

[Vascular injuries complicating osteosynthesis in proximal femur fractures]. / Gefässverletzungen bei Osteosynthesen proximaler Femurfrakturen.

While there are quite a number of reports on vascular injuries complicating hip arthropasty by acetabular component screw fixation, retractor tip pressure or extruding bone cement, the incidence of deep femoral vessel injuries in operative fixation of proximal femoral fractures is comparatively seldom described. We report on two patients with per- and subtrochanteric femoral fractures who sustained injuries of deep femoral artery branches during the implantation of a dynamic hip screw (DHS) and a dynamic condylar screw (DCS), which resulted in a massive thigh hematoma and a fist-size pseudoaneurysm respectively and necessitated surgical intervention in either case. We blame these vascular injuries on the pressure of Hohmann retractors exposing the femoral bone or on the drilling of boreholes for plate attachment. After discussing various operative procedures, we conclude that intramedullar implants are safer than plates with regard to potential vascular complications.

Evaluation of different transvaginal sonographic diagnostic parameters in women with postmenopausal bleeding.

OBJECTIVE: To determine whether the accuracy of transvaginal sonography to detect endometrial pathology is enhanced by assessing endometrial morphology and the regularity of the endometrial border in addition to measurement of endometrial thickness in women with postmenopausal bleeding. DESIGN AND METHODS: A total of 159 women with postmenopausal bleeding were included in a prospective study performed at the Clinic of Obstetrics and Gynecology, University of Mainz. The results obtained on transvaginal sonographic assessment of the endometrium were compared with the histological evaluation of the operative endometrial specimen. RESULTS: A cut-off level for endometrial thickness of 5 mm had a sensitivity of 94%, specificity of 48% and positive and negative predictive values of 69% and 87%, respectively for the presence of endometrial pathology. Assessment of the regularity of the endometrial border showed a sensitivity of 75%, specificity of 66% and positive and negative predictive values of 73% and 69%, respectively. For the third sonographic parameter, endometrial morphology, the sensitivity was 82%, specificity 64%, the positive predictive value 73% and the negative predictive value 74%. The combined consideration of the three sonographic parameters showed a sensitivity of 97%, specificity of 65%, and positive and negative predictive values of 80% and 94%, respectively. CONCLUSION: The combined evaluation of endometrial thickness, endometrial morphology and the endometrial border enhances the accuracy of transvaginal sonography to detect endometrial pathology in women with postmenopausal bleeding, thus facilitating the decision regarding further diagnostic and therapeutic measures.

[Paraneoplastic IgA nephritis as the initial symptom of bronchial carcinoma]. / Paraneoplastische IgA-Nephritis als Erstsymptom eines Bronchialkarzinoms.

We report on a 45-year old patient who was treated for IgA-Nephritis for 9 months. During treatment he developed coughing and dyspnoea which led to diagnose a central stenosing NSCLC at the tracheobronchial angle. Cancer treatment by x-ray showed a good response, e.g. significant reduction of cancer volume and a remarkably improved renal function. In the course of tumour progression (3 months after initial treatment) retention parameter deteriorated again and the patient needed to be dialysed. Palliative laser therapy had no influence on renal function. The close linkage between tumour regression and the extent of IgA nephritis suggest that the preceding IgA nephritis was paraneoplastic and hence a primary symptom of the NSCLC.

[Infections following osteosynthesis in childhood]. / Infektionen nach Osteosynthesen im Kindesalter.

We report 313 cases of osteosynthesis seen between 1977 and 1987 in our hospital. In 50 cases wound infection occurred and in 4 cases osteomyelitis. Important factors in the development of wound infection are soft tissue damage, duration of operation, time from accident to operation, and operation at night. The 4 cases of osteomyelitis occurred in patients who had undergone previous operations. All wound infections healed with local therapy and systemic antibiotics; the cases of osteomyelitis required surgical intervention and systemic antibiotics. No late defects or complications were seen in any case.

[Studies of necrotizing enteritis of suckling piglets (Cl. perfringens typc C enterotoxemia) in industrialized sow breeding units. 3. Experimental reproduction of the disease]. / Untersuchungen zur nekrotisierenden Enteritis der Saugferkel (Cl.-perfringens-Typ-C-Enterotoxämie) in industriemässig produzierenden Sauenzuchtanlagen. 3. Mitteilung: Experimentelle Reproduktion der Krankheit.

Experimental reproduction of necrotising enteritis of sucking pigs was successfully achieved by using both Clostridium perfringens Type C strains, which had been isolated from sucking pigs with necrotising enteritis, and Type C strain 3628 of A.T.C.C. (sub-type C1). The lethal dose for sucking pigs was between 20 X 10(6) and 12 X 10(7) pathogens per animal. The disease could not even be induced by repeated application of no-bacterial toxin of Cl. perfringens Type C nor by administration of Cl. perfringens Type A strains which had been cultured from broilers with necrotising enteritis. Necrotising enteritis was found to develop in two phases in sucking pigs. First, the pathogen will deposit to the villous epithelium and then penetrate the superficial strata of the mocous membrane. In the second phase, the villous structure will be destroyed by the lethal, haemolysing, and necrotising toxins of Cl. perfringens. The role played by individual toxin fractions is discussed together with the importance of humoral and localised infection defence. Sucking pigs may be sufficiently protected against infection based on single or ten-fold lethal infectious dosage by two vaccinations of the mother animal, five and three weeks prior to parturition, using "Enterotoxaemia Vaccine Dessau bivalent". Infection then would not occur unless a hundredfold lethal dose was applied. Characteristics include diarrhoea, apathy, exhaustion, and death.