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Biomedical subjects

R Zimmermann

Publications and source records attributed to R Zimmermann.

571 records · Page 32Linked to original sources
PubMedDate not supplied

Sequential occurrence of IgM, IgM/IgG, and gp120-IgM/IgG complement complexes on CD4+ lymphocytes in relation to CD4+ blood lymphocyte depletion in HIV+ hemophilia patients: results of a 10-year study.

The concept of autoimmune mechanisms playing an integral role in the pathogenesis of HIV disease is rapidly gaining ground. In this study, we determined IgM and IgG antibodies, complement fragments and gp120 on the surface of CD4+ lymphocytes using double-fluorescence flow cytometry. Sequential analysis demonstrated an inverse relationship of autoantibodies and CD4+ lymphocyte counts in the peripheral blood. HIV+ patients without autoantibodies (16/104 = 15%) had the highest CD4+ blood cell counts (324 +/- 264/microliters; mean +/- SD). CD4+ counts were successively lower in patients with complement-fixing IgM (243 +/- 240/microliter), complement-fixing IgG and IgM (139 +/- 138/microliter), or gp120-IgM/IgG complement complexes on the surface of CD4+ cells (38 +/- 45/microliter, P = 0.03). Individual patient profiles show that IgM autoantibodies typically are formed early after HIV infection and appear to deplete CD4+ lymphocytes very slowly, whereas complement-fixing IgG autoantibodies are generated at a later stage and deplete CD4+ lymphocytes more efficiently. The presence of both soluble gp120 and complement-fixing autoantibodies on CD4+ lymphocytes is associated with very low CD4+ cell counts and coincides with progression to terminal disease. Early during HIV infection autoantibody production is rather unstable, but it becomes more stable with disease progression and persists in advanced stages of the disease. These data suggest that autoantibody formation against CD4+ lymphocytes is a pathogenic mechanism for CD4+ cell depletion.

Antigen-Antibody Complex↗
PubMedDate not supplied

Ribonucleoparticle-independent import of proteins into mammalian microsomes involves a membrane protein which is sensitive to chemical alkylation.

Import of the small precursor protein preprocecropin A (ppcec A) into dog pancreas microsomes under post-translational conditions does not involve the ribonucleoparticles, signal recognition particle and ribosome, and their receptors on the microsomal surface, docking protein and ribosome receptor. In this study, we attempted to obtain direct evidence for the involvement of proteinaceous membrane components in this alternative import mechanism by utilizing various sulfhydryl-modifying reagents (N-ethylmaleimide (NEM), N-iodoacetylaminoethyl-5-naphthylamine-1- sulphonic acid (AEDANS) and iodoacetamide (IAA]. As a result of observing the inhibitory effect of 2 reagents (NEM and AEDANS) on the microsomes with respect to ppcec A-import, we concluded that there is at least one membrane protein with a cytoplasmically exposed sulfhydryl involved in ppcep A-import. This membrane protein(s) is (are) distinct from membrane proteins which are known to be involved in protein import, such as the signal peptidase and the so-called signal sequence receptor.

Alkylating Agents↗
PubMedDate not supplied

Identification of surrogate compounds for the emission of PCdd/F (I-TEQ value) and evaluation of their on-line real-time detectability in flue gases of waste incineration plants by REMPI-TOFMS mass spectrometry.

Correlations between products of incomplete combustion (PIC), e.g., chloroaromatic compounds, can be used to characterise the emissions from combustion processes, like municipal or hazardous waste incineration. A possible application of such relationships may be the on-line real-time monitoring of a characteristic surrogate, e.g., with Resonance-Enhanced Multiphoton Ionization-Time-of-Flight Mass Spectrometry (REMPI-TOFMS). In this paper, we report the relationships of homologues and individual congeners of chlorinated benzenes (PCBz), dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and phenols (PCPh) to the International Toxicity Equivalent (I-TEQ) of the PCDD/F (I-TEQ value) in the flue gas and stack gas of a 22 MW hazardous waste incinerator (HWI). As the REMPI detection sensitivity is decreasing with the increase of the degree of chlorination, this study focuses on the lower chlorinated species of the compounds mentioned above. Lower chlorinated species, e.g., chlorobenzene (MCBz), 1,4-dichlorobenzene, 2,4,6-trichlorodibenzofuran or 2,4-dichlorophenol, were identified as I-TEQ surrogates in the flue gas. In contrast to the higher chlorinated phenols, the lower chlorinated phenols (degree of chlorination <4) were not reliable as surrogates in the stack gas. The identified surrogates are evaluated in terms of their detectability by REMPI-TOFMS laser mass spectrometry. The outcome is that MCBz is the best suited surrogate for (indirect) on-line measuring of the I-TEQ value in the flue gas by REMPI-TOFMS. The correlation coefficient r of the MCBz concentration to the I-TEQ in the flue gas was 0.85.

Journal Article↗
PubMedDate not supplied

On-line real-time measurements at incineration plants: PAHs and a PCDD/F surrogate compound at stationary combustion conditions and during transient emission puffs.

Laser mass spectrometry has been applied for on-line monitoring of traces of aromatic compounds from flue gas of incineration plants. The experiments have been carried out at two sampling sites in an industrial hazardous-waste incinerator. With laser mass spectrometry resonance-enhanced multiphoton ionization (REMPI) with time-of-flight mass spectrometry (TOFMS) (REMPI-TOFMS), using the group selective multi-component monitoring approach, aromatic compounds are selectively ionized from the complex flue-gas matrix. In this case, the result of an REMPI-TOFMS on-line measurement is a distinct pattern of aromatic compounds. These patterns are dependent on: (i) the point of measurement, (ii) the incineration plant, (iii) the temperature, and (iv) the fuel. This contribution focuses on the fuel dependence of the pattern. The most transient behavior can be observed when containers filled with hazardous waste are burnt, leading to puffs. Real-time monitoring results of puffs are given. Furthermore, as an approach towards on-line monitoring of the TEQ (PCDD/F toxicity equivalent), REMPI-TOFMS on-line analysis results of chlorobenzene are presented.

Journal Article↗
PubMedDate not supplied

Influence of combustion conditions on the PCDD/F-, PCB-, PCBz- and PAH-concentrations in the post-combustion chamber of a waste incineration pilot plant.

Experiments at a pilot scale waste incinerator (0.5 MW thermal power) showed that the conditions in the post-combustion chamber (650-900 degrees C) are strongly influencing the formation of chlorinated and non-chlorinated aromatics. Non-optimal combustion conditions resulted in increased concentrations of mono- to trichlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and polycyclic aromatic hydrocarbons (PAH), while chlorinated benzenes (PCBz), polychlorinated biphenyls (PCB) and the higher chlorinated PCDD/F are only weakly affected or even decrease. The changes in concentration of the compounds investigated over a time span of hours gave hints on 'memory effects' in this combustion zone. For mono- and dichlorinated benzenes, a high correlation (r2 = 0.80) with the international toxicity equivalent (I-TEQ) value of PCDD/F was observed. As recently has been demonstrated, this correlation can be utilized for an indirect on-line measurement of the I-TEQ by a novel laser mass spectrometric technique (REMPI-TO-FMS).

Benzofurans↗
PubMedDate not supplied

[Tongue ultrasound and pressure measurement in infantile sucking. Initial results].

The sucking procedure was examined in 10 healthy, term infants and in one newborn with disturbed sucking actions suffering from recurrent aspiration pneumonia. We applied ultrasonography of the tongue and simultaneous intraoral pressure measurements in the examinations. Observations were made with a bottle feeding system (NUK). Sonography and intraoral measurements both gave reliable informations. Parallel recordings of tongue dorsum movements by pseudo-3-dimensional imaging and simultaneously obtained pressure curves show, that increasing suction is maintained by withdrawing the tongue dorso-cranially. Computer-aided evaluation of ultrasound images and pressure data demonstrate the possibility to distinguish between coordinated and uncoordinated sucking movements. Simultaneous use of both examination techniques can be helpful in diagnosis and documentation of disturbed sucking actions.

Female↗
PubMedDate not supplied

Endothelin does not contribute to the attenuation in myocardial function and blood flow after repetitive ischemia in the rat heart.

An increased release of the potent vasoconstrictor endothelin (ET) may play a role in the development of myocardial stunning. We, therefore, hypothesized that blockade of ET with either monoclonal antibodies against ET-1 and ET-3 (a-ET1/3-ab) or with the ET(A) receptor antagonist BQ123 would improve the reduction in myocardial blood flow (MBF; H2 clearance) and fractional wall thickening (FT; pulsed Doppler) after repetitive ischemia/reperfusion in an in situ perfused rat model. Under baseline conditions, ET-1 dose dependently decreased MBF and increased mean arterial blood pressure. FT and heart rate were unaltered. Pretreatment with both a-ET1/3-ab or BQ123 effectively blocked the effects of ET. Following repetitive ischemia, MBF was significantly reduced from 3.5 +/- 0.4 to 2.1 +/- 0.3 ml x min-1 x g-1 (p < 0.05) and FT from 16.2 +/- 1.7 to 9.4 +/- 1.1% in the control group (p < 0.05). Pretreatment with either antibodies did not significantly improve the attenuation in MBF and FT at the end of the ischemic protocol. These results indicate that inhibition of ET-1 by monoclonal antibodies or by ET(A) receptor blockade does not influence the decrease in MBF and FT in repetitive ischemia/reperfusion. We, therefore, propose that ET is not a major determinant in the development of myocardial stunning.

Animals↗
PubMedDate not supplied

A large unilateral contained urinoma in a fetus: an indication for intrauterine urinary shunting.

A large contained urinoma measuring 12 x 8 x 8 cm3 was diagnosed in the left kidney of a female fetus at 28 weeks gestation. Analysis of fluid from serial punctures of the cyst indicated that renal function on that side was poor, but because ultrasound findings of the thorax suggested lung growth impairment, a shunt was inserted. After 3 weeks the shunt dislocated into the fetal abdominal cavity and urinous ascites developed. The ascites was found to have resolved spontaneously on ultrasonography 3 weeks later. The infant was delivered at 37 weeks gestation and appeared normal except for bilateral pelvi-ureteric obstruction. This was much worse in the left kidney, the renal function of which was only 10% of normal. A left nephrectomy was carried out when the infant was 6 months old, when the inner part of the shunt was discovered in perinephric fibrous tissue. The renal pelvis was greatly enlarged and fibrotic; no site of rupture could be identified. The infant's respiratory function was normal. This case suggests the use of intrauterine shunting to decompress a large unilateral urinoma resulting in marked elevation of the fetal diaphragm to prevent impairment of fetal lung growth.

Adult↗
PubMedDate not supplied

[Osteosynthesis by adherent plates. An experimental physical study].

The creation of ridges of the deep surface of plates used for osteosynthesis increases their adherence to bone. By increasing the coefficient of friction between the plate and the bone, the stresses taken by the screws can be diminished by a third. The procedures diminishes by the same amount the risk of stripping or loosening of screws and thus the risk of pseudarthrosis. Experimental study has been made by measurement with the aid of an elliptometer and modifications in the state of polarization of a Lawer beam under the influence of shearing strains. The strains were those imposed on screws in Araldite fixing a plate whose inferior surface was smooth on one end and ridged on the other. The ridges should not be such as to prevent the later removal of the plate. Screws should be applied for preference with a dynamometric screwdriver because the stress relief is maximal with a tightening force of 12 inch pounds.

Animals↗
PubMedDate not supplied

Endothelin plasma levels in acute graft rejection after heart transplantation.

BACKGROUND: Endothelin is an oligopeptide of endothelial origin with potent vasoconstrictive and mitogenic properties, implicated in the pathogenesis of cyclosporine-induced hypertension, graft vasculopathy, and renal failure. Experimental animal data suggest a role for endothelin in allograft rejection also. METHODS: To determine the role of endothelin in acute graft rejection after heart transplantation, we determined endothelin plasma levels in 165 blood samples from 79 cardiac allograft recipients (2 to 81 months after the operation) with normal graft function and correlated our findings with the histologic severity of acute graft rejection according to International Society for Heart and Lung Transplantation grading. For comparison endothelin levels were determined in 30 healthy controls and in 22 early postoperative transplant recipients (< 2 months after the operation). RESULTS: Endothelin plasma levels were significantly higher in transplant recipients than in controls (early postoperative: 7.97 = 7.53 pg/ml; late postoperative: 3.68 +/- 1.72 pg/ml; controls: 1.55 +/- 0.89 pg/ml). Endothelin plasma levels were not significantly different between groups of rejection grades 0 to 4. In the comparison of two groups of no rejection or lower (International Society for Heart and Lung Transplantation grade 0 and 1, n = 134) and higher (International Society for Heart and Lung Transplantation grade > or = 2, n = 31) rejection severity or comparing patients requiring rejection therapy (n = 20) with those not requiring therapy (n = 145), endothelin levels did not differ significantly between the groups. In 22 patients with three to six available consecutive biopsy scores and endothelin levels, intraindividual longitudinal analysis did also not show any significant correlation. The only positive correlation of endothelin levels with other laboratory parameters was found with serum creatinine concentrations (p < 0.001). In the early postoperative recipients, no correlation of endothelin plasma levels with rejection severity was seen; furthermore the only significant association was found with time after operation. CONCLUSIONS: In this study endothelin plasma levels were not influenced by acute allograft rejection after heart transplantation. Therefore endothelin levels do not appear to be a useful marker for noninvasive rejection diagnosis. Furthermore, a relevant pathogenetic role of endothelin in the rejection process cannot be derived from these data.

Acute Disease↗
PubMedDate not supplied

[Single intrauterine fetal death in twin pregnancy].

During a 11 year period (1984-1994) we identified and analysed at the Department of Obstetrics, University Hospital of Zurich, among 541 twin pregnancies 19 with single intrauterine death (SIUD) in the second and third trimester. The preterm delivery rate was 68% and much higher compared to singleton pregnancies at the same institution (17%). The caesarean section rate was 47% and also higher compared to singleton pregnancies (21%) but lower than in a normal twin collective (61%). Two of the surviving twins showed malformations. One of them has in addition of porencephaly, probably due to disruption syndrome. In 12 out of 19 case a monochorionic placenta was found including 5 with twin-twin transfusion syndrome. Surprisingly 8 out of 19 dead fetuses had a velamentous insertion of the umbilical cord. This might suggest a causal relationship to SIUD. 95% showed the same sex. Maternal blood coagulation disorders are rare. From our results we conclude that SIUD is associated with an increased preterm delivery and caesarean section rate. Monochorionic twins and twins with concordant sex demonstrate the highest risk for SIUD. The twin-twin transfusion syndrome is the main single cause for SIUD. The pathophysiologic role of velamentous insertion remains unclear.

Adult↗