Vinylsiloxanether: A New Impression Material. Clinical Study of Implant Impressions with Vinylsiloxanether versus Polyether Materials

Aim: The performance of three elastomeric materials for the open monophase implant impressions technique was tested under the following clinical conditions: polyether (IM) and vinylsiloxanether without (ID) and with additional simultaneous splinting of the implant impression copings with a higher shore hardness A‐silicone (IDF). Materials and Methods: The three test groups, IM, ID, and IDF, were randomly allocated 10 test subjects with three to five implants each. The impressions were analyzed regarding the subjective clinical assessments with 11‐point rating scales by the dentist, the patient, and the dental technician, as well as to the comparison of these assessments with the objectified clinical fit of the manufactured crowns based on standard clinical evaluation criteria. The three groups were statistically analyzed on the basis of the hypothesis of non‐inferiority of ID versus IM and IDF versus IM (alpha < 0.05). Results: The results of the study showed the objective clinical fit of the dental prostheses made using ID being comparable to the results obtained with IM. Compared with ID and IM, the precision of fit attained with IDF was reduced, although the subjective dentist assessments of IDF were in parts significantly better than those of IM and ID (p = .015). A statistically significant superiority of ID in comparison with IM could be determined with regard to the subjective ratings of the taste by the test subject (p < .01), of the handling (p < .001) and of the precision details of impression (p = .012) by the dentist, and of removing the plaster model from the mold by the dental technician (p = .017). Conclusions: The overall results of the vinylsiloxanether material in terms of the patients', dentists', and dental technicians' assessments proved to be equivalent or superior to those of the polyether material. The IDF technique cannot be recommended for this application.     

Myocardial infarction in old people. The influence of diabetes mellitus

The clinical features and outcome were determined for 100 consecutive patients aged 65 years or older with a history of diabetes mellitus who presented to hospital with acute myocardial infarction. Each case was compared with an age- and sex-matched nondiabetic control also admitted to hospital with acute myocardial infarction. Chest pain was equally common in both groups and was the main presenting symptom. Cardiac failure was a more frequent accompaniment in the diabetics, despite the lack of evidence for greater infarct size in this group. The outcome was worst for female diabetics, of whom 46% died. Contrary to popular teaching, painless myocardial infarction is not a specific feature of elderly diabetics.     

Membrane-associated sickle hemoglobin: a major determinant of sickle erythrocyte rigidity

Micropipette aspiration tests on single erythrocytes have previously shown that the static rigidity (membrane shear modulus) of oxygenated sickle cells increased with increasing hemoglobin concentration, whereas the rigidity of normal cells was independent of hemoglobin concentration. Moreover, it was observed that after mechanical extension, sickle cells exhibited persistent deformation more frequently and to a greater extent than normal cells. To ascertain if differences in association of normal and sickle hemoglobin with the membrane could account for these observations, we measured rheologic properties of normal membranes reconstituted with sickle hemoglobin and sickle membranes reconstituted with normal hemoglobin. The static rigidity of normal ghosts reloaded with sickle hemoglobin was higher than those of either normal ghosts reloaded with normal hemoglobin or native normal cells. On the other hand, the increased rigidity of native sickle cells decreased to near-normal values following reconstitution with normal hemoglobin. Furthermore, we observed that normal ghosts reconstituted with sickle hemoglobin exhibited persistent bumps after mechanical extension, but no bumps formed on normal ghosts reconstituted with normal hemoglobin. Moreover residual bumps were not produced on sickle cells reloaded with normal hemoglobin. Since mechanical characteristics peculiar to sickle cells could be induced in normal cells by incorporation of sickle hemoglobin, and since normal characteristics could be restored to sickle cells by incorporation of normal hemoglobin, we suggest that the interaction of sickle hemoglobin with the cell membrane is responsible for augmented static rigidity of oxygenated sickle erythrocytes.     

Expression of CD27 and its ligand, CD70, on chronic lymphocytic leukemia B cells

Crosslinking the CD27 antigen on T cells provides a costimulatory signal that, in concert with T-cell receptor crosslinking, can induce T- cell proliferation and cellular immune activation. We find that chronic lymphocytic leukemia (CLL) B cells from most patients coexpress both membrane-bound and soluble CD27, along with its newly identified ligand, CD70. The expression of soluble CD27 may preclude leukemic B cells from stimulating T cells via CD70, thereby potentially impairing their ability to function as effective antigen-presenting cells. We find that leukemic B-cell expression of soluble and membrane-bound CD27 can be downmodulated through a CD40-dependent signal. This signal also induces enhanced expression of CD70 on both normal and leukemic B cells. We find that tumor necrosis factor (TNF)-alpha, or the Th1 cytokine interferon (IFN)-gamma, also can induce downmodulation of CD27, whereas Th2-associated cytokines interleukin-4 (IL-4) or IL-10 can enhance leukemic B-cell expression of this accessory molecule. The modulation of CD27 induced by these conditions is accompanied by reciprocal changes in the expression levels of CD70, suggesting that these accessory molecules may be engaged in reciprocal receptor-ligand downmodulation. Consistent with this, we observe that co-culture of CLL B cells with transfected murine plasmacytoma cells that express human CD70 affects downmodulation of CD27 and enhanced expression of CD70 on leukemic B cells, but does not affect expression of CD27 mRNA. However, we find that CD40-crosslinking, in addition to reducing the level of CD27 protein, also reduces leukemic B-cell expression of CD27 mRNA. This argues that the changes in the expression levels of CD27 following CD40-signaling are not simply due to induced increases in the expression levels of CD70. Finally, we demonstrate that reciprocal changes in expression of CD27 and CD70 may contribute to the enhanced antigen-presenting capacity of CLL B cells after CD40-dependent leukemic B-cell activation. These findings expand the understanding of the regulation of costimulatory molecules important in antigen presentation and also have implications for the immunobiology of and therapy for CLL.     

High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy

Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.     

Pathogenesis of streptococcal and staphylococcal endocarditis

Although streptococcal and S. aureus IE share the same primary site of infection, their pathogenesis and clinical evolution present several major differences. Streptococci adhere to cardiac valves with pre-existing endothelial lesions. In contrast, S. aureus can colonize either damaged endothelium or invade physically intact endothelial cells. These interactions are mediated by multiple surface adhesins, some of which have been only partially characterized. Streptococci produce surface glucans (gtf and ftf), ECM adhesins (e.g., fibronectin-binding proteins, FimA), and platelet aggregating factors (phase I and phase II antigens, pblA, pblB, and pblT), all of which have been.     

Cardiac arrests in a geriatric unit

The outcome of cardio-pulmonary resuscitation within an acute geriatric unit was studied in 95 patients (mean age 77 years, range 65-90) who were involved in 106 consecutive cardio-respiratory arrest calls. In 58 patients (61%), initial resuscitation was unsuccessful and a further 21 (22%) died later in hospital. Fourteen patients (15%) were alive 3 months after hospital discharge, a success rate comparable to that of published series in younger patients. The probability of successful resuscitation was greater in patients in the High-dependency Unit, and ventricular fibrillation and a short duration of arrest were confirmed as good prognostic factors. Age had no influence on outcome. Although subjective levels of psychological and physical disability of survivors at 3 months were low, their domestic and social life was often excessively restricted. Selective, but positive, use of cardio-pulmonary resuscitation within acute geriatric units will benefit a significant minority of patients, but there is also a need for further measures to reduce unnecessary disability in long-term survivors.     

Serious infections in adults due to group B streptococci: Clinical and serotypic characterization

Serious infections in adults due to group B streptococci have been infrequently reported. We describe 24 such patients. Bacteremic pyelonephritis, pneumonitis and endometritis were the most common clinical syndromes observed. Group B streptococcal infections tended to occur in patients with underlying illnesses, particularly genitourinary disorders and diabetes mellitus. Mortality was surprisingly low (8 per cent). Type III was the serotype most commonly isolated, and there was no significant correlation of different serotypes with specific organ-system involvement. Group B streptococcal isolates from these patients were uniformly sensitive to penicillin, ampicillin, cephalothin, chloramphenicol, erythromycin and clindamycin; all were highly resistant to kanamycin. Eighty-seven per cent were resistant to tetracycline. Although consistently sensitive to penicillin, the minimal inhibitory concentrations were significantly higher for group B than group A streptococci (p < 0.0005).