Search PubMed⌕ Search

Biomedical subjects

S Ziegler

Publications and source records attributed to S Ziegler.

70 records · Page 4Linked to original sources
PubMed1993

Fluorodeoxyglucose imaging of advanced head and neck cancer after chemotherapy.

Positron emission tomography (PET) was applied to evaluate therapeutic effects in patients with advanced head and neck cancer for use in monitoring therapy. In 18 patients with histologically proven head and neck cancer, PET studies with 330-440 MBq 18F-fluorodeoxyglucose (FDG) were performed prior to the first chemotherapeutic cycle with cisplatin and 5-FU. A second examination after the first chemotherapeutic cycle was performed in 11 patients. Tumor or lymph node volumes were determined from CT slices and the growth rate was calculated assuming an exponential function. Uptake in a region of interest was used for the quantitative evaluation of the PET images after standardization to injected dose and body weight. FDG data were available for 6 tumors and 10 metastases, volumetric data for 5 tumors and 7 metastases. One lesion showed an increase, seven a decrease in FDG uptake and eight lesions remained unchanged. Multiple lymph nodes in the same patient showed different baseline metabolisms and also different changes following therapy. Tumors were more sensitive to therapy than lymph node metastases. The growth rate and the change in FDG uptake were highly correlated with different regression functions for tumors and lymph node metastases. These data demonstrate that PET with FDG can be used to assess early chemotherapeutic effects. The information gained with PET can be included for treatment planning in patients undergoing systemic chemotherapy.

Adult↗
PubMed1992

Contractile behaviour of skinned papillary muscle in mitral valve disease.

The contractile behaviour of Triton-X 100 skinned left ventricular papillary muscle from 19 patients undergoing cardiac surgery for mitral valve stenosis: n = 6, mitral valve incompetence: n = 7, or combined mitral valve disease: n = 6 was analyzed. At supramaximal activation the "vibration induced force clamping technique" was used for isometric analysis of time course and extent of isometric postvibration force recovery. Afterloaded contractions were applied for extrapolation of the maximum shortening velocity at zero load (Vmax). The Calcium sensitivity was analysed by variation of the free EGTA-buffered Calcium concentration at a passive resting force of 2 mN at 26 degrees C. In different types of mitral valve disease the characteristics of isometric force development were unaltered in terms of maximum force development, force per square mm, Calcium sensitivity and the time course of isometric contraction after force clamping. However the capability to shorten as expressed by Vmax was reduced in mitral valve incompetence (3.87 +/- 0.37 ML/s) as compared with mitral valve stenosis (5.29 +/- 0.35 ML/s) or combined mitral valve disease (4.83 +/- 0.51 ML/s). The ratio between the inverse value of Vmax and the time constant of isometric force development after force clamping was significantly different in mitral valve incompetence as compared with other types of mitral valve disease (p < 0.0001). These data argue for the presence of different resistances against shortening in various types of mitral valve disease, due to altered cross-bridge cycling characteristics or to morphological factors.

Adult↗
PubMed1992

Chromatographic separation of serum proteins and estimation of their zinc and copper content.

Human serum proteins of blood donors and dialysis patients were separated by means of gel filtration chromatography. The resulting fractions were analyzed for copper and zinc. Separation resulted in 3 zinc peaks with a molecular weight of about 700,000, 300,000, and 75,000 Dalton, with alpha 2-macroglobulin co-eluting in the first and albumin co-eluting in the third zinc peak. The zinc protein(s) of the second peak remained unidentified. The three peaks contained, in succession, 0.72 +/- 0.30 mumol/L (4.8 +/- 1.6%), 1.26 +/- 0.37 mumol/L (8.5 +/- 1.7/1000) and 12.8 +/- 2.1 mumol/L (86.8 +/- 2.8%) of total zinc in the case of blood donors, and 1.19 +/- 1.05 mumol/L (9.2 +/- 7.2%), 0.97 +/- 0.22 mumol/L (8.0 +/- 2.6%), and 10.4 +/- 1.66 mumol/L (82.7 +/- 6.7%) in the case of dialysis patients. Separation followed by copper analysis resulted in the three peaks, as well, with a molecular weight of about 750,000, 140,000, and 75,000 dalton. The copper protein of the first peak remained unidentified, while coeruloplasmin co-eluted in the second and albumin in the third peak. The three peaks contained, in succession, 0.4 +/- 0.16 mumol/L (2.3 +/- 0.95%), 14.6 +/- 0.7 mumol/L (83.9 +/- 4.1%), and 2.4 +/- 0.6 mumol/L (13.7 +/- 3.5%) of total copper in the case of blood donors, and 0.5 +/- 0.73 mumol/L (2.2 +/- 3.2%), 19.5 +/- 1.1 mumol/L (90.5 +/- 4.9%), and 1.6 +/- 0.66 mumol/L (7.3 +/- 3.0/1000) in the case of dialysis patients. Limitation of the method is shown regarding separation of major from minor proteins and albumin from transferrin.

Blood Donors↗
PubMed1991

Effects of polychlorinated biphenyls in rat liver: correlation between primary subcellular effects and promoting activity.

In the present study the promoting activity of various PCB and PBB isomers and congeners in rat liver has been studied and compared with a variety of primary xenobiotic-mediated enzymatic changes in this target organ. Female Wistar rats were given diethylnitrosamine (DEN; 10 mg/kg body wt for 10 days) and were subsequently treated once weekly with polychlorinated biphenyls (150 or 15 mumol/kg body wt) for a total of 8 weeks. Additional groups of rats were administered 3,3',4,4'-tetrabromobiphenyl or 3-methylcholanthrene (8 weekly injections of 15 or 150 mumol/kg body wt, respectively) or were given phenobarbital (0.05% in the diet) until the end of the experiment. Reference groups were treated with the various test compounds without prior initiation. One week and 9 weeks after cessation of promoter treatment rats were killed and the volumetric fraction of enzyme-altered foci characterized by changes in adenosine triphosphatase and gamma-glutamyl transpeptidase activity was determined as a means to quantitatively assess the extent of preneoplastic response in this organ. Out of the series of polyhalogenated biphenyls tested, promoting effects were seen with the following compounds: 2,2',4,5'-tetrachlorobiphenyl, 3,3',4,4'-tetrachlorobiphenyl, 2,3,4,4',5-pentachlorobiphenyl, and 3,3',4,4'-tetrabromobiphenyl, whereas no significant effects were obtained with 4-monochlorobiphenyl. In rats not treated with DEN, the two strongly promoting agents 2,3,4,4',5-pentachlorobiphenyl and 3,3',4,4'-tetrachlorobiphenyl also significantly increased the volume fraction of enzyme-altered foci over the respective controls when analyzed at the second time point of investigation. In parallel experiments, induction of liver growth and of microsomal cytochrome P450 content in liver was found to correlate well with the promoting activity of the various xenobiotics, suggesting that these parameters may be used to predict the promoting activity of polyhalogenated biphenyls in a short term assay.

Adenosine Triphosphatases↗
PubMed1991

Glucose uptake, perfusion, and cell proliferation in head and neck tumors: relation of positron emission tomography to flow cytometry.

The uptake of 18F-Deoxyglucose (FDG) was studied in vivo in relation to the proliferation rate of human head and neck tumors. Forty-two patients with histologically proven squamous-cell carcinoma of the head and neck and four patients with metastases of head and neck tumors were examined with PET and FDG prior to surgery. In 35 of these patients, a flow cytometric analysis of the DNA content and the proliferation rate was done using one-dimensional flow cytometry rate was done using one-dimensional flow cytometry (DAPI staining). In 17 cases, perfusion studies with 15O-labeled water were performed. Twenty-seven specimens were evaluable by flow cytometry. The analysis of the distribution of the FDG uptake revealed two groups, showing a high and a lower uptake pattern. In both groups the FDG uptake and the proliferation rate were correlated with an r-value of 0.64 and 0.8 respectively. However, the slope of the regression function was flat. No correlation was found between the perfusion and the proliferation rate. It is suggested that these differences in uptake in histologically identical tumor populations may correspond to differences at the molecular level, e.g., differences in the amount of the glucose carrier, perhaps caused by oncogenic transformation.

Carcinoma, Squamous Cell↗
PubMed1981

The effects of hospitalization on children's behavior: a review of the literature.

The literature on the behavioral effects of hospitalization on children is reviewed. This body of literature, which includes both theoretical and empirical studies, covers a span of four decades. The work can be divided roughly into two areas of concern: the first to document negative effects and the second to describe ameliorative efforts. The final section of the paper reviews attempts to integrate research findings into pediatric practice.

Child↗
PubMedDate not supplied

Complement resistance of tumor cells: basal and induced mechanisms.

Clinical and experimental studies have suggested that complement may play a role in tumor cytotoxicity. However, the efficiency of complement-mediated tumor cell lysis is hampered by various protective mechanisms, which may be divided into two categories: basal and induced mechanisms. The basal mechanisms are spontaneously expressed in cells without a need for prior activation, whereas the induced mechanisms develop in cells subjected to stimulation with cytokines, hormones, drugs or with sublytic doses of complement and other pore-formers. Membrane-associated complement regulatory proteins, such as CD55 (DAF, Decay-Accelerating Factor), CD46 (MCP, Membrane Cofactor Protein), CD35 (CR1, Complement Receptor type 1) and CD59, which serve as an important mechanism of self protection and render autologous cells insensitive to the action of complement. appear to be over-expressed on certain tumors. Furthermore, tumor cells secrete several soluble complement inhibitors. Tumor cells may also express proteases that degrade complement proteins, such as C3, or ecto-protein kinases which can phosphorylate complement components, such as C9. Besides this basal resistance, nucleated cells resist, to some extent, complement damage by removing the membrane attack complexes (MAC) from their surface. Several biochemical pathways, including protein phosphorylation, activation of G-proteins and turnover of phosphoinositides have been implicated in resistance to complement. Calcium ion influx and activation of protein kinase C (PKC) and of mitogen-activated protein kinase (MAPK) have also been demonstrated to be associated with the complement-induced enhanced resistance to lysis. The complete elucidation of the molecular mechanisms involved in basal and induced tumor cell resistance will enable the development of strategies for interfering with these evasion mechanisms and the use of the cytotoxic complement system against tumor cells.

Animals↗
PubMedDate not supplied

Scintigraphic evaluation of cardiac autonomic innervation.

Alterations in cardiac autonomic neuronal function have become the focus of intense research in various cardiovascular diseases. Both single-photon emission tomography (SPECT) and the positron emission tomography (PET) imaging techniques in combination with radio-labeled neurotransmitters and receptor ligands have become available for the scintigraphic visualization of presynaptic and postsynaptic neuronal function. Several clinical studies have shown changes in tracer distribution in different clinical conditions, such as ischemic heart disease, congestive heart failure, malignant arrhythmias, heart transplantation, and in patients with diabetes. In patients with congestive heart failure, previous in vitro investigations have concentrated on the postsynaptic level of the sympathetic innervation. However, alterations in presynaptic nerve function have been demonstrated with scintigraphic investigations by decreased presynaptic tracer retention. Moreover, correlation between scintigraphic findings and clinical outcome was shown in patients with heart failure, providing important prognostic information superior to conventional risk assessment. In conclusion, scintigraphic evaluation by SPECT and PET allows functional characterization of cardiac presynaptic and postsynaptic neurons. Regional tracer uptake can be used as an index for the integrity of innervation in various diseases. Newer tracer approaches may allow the noninvasive quantification of neuronal function by PET.

Autonomic Nervous System↗
PubMedDate not supplied

Differential diagnosis of CNS lesions in AIDS patients by FDG-PET.

OBJECTIVE: The aim of this study was to evaluate the potential of FDG-PET in the differential diagnosis of CNS lesions in patients with AIDS, particularly to differentiate between toxoplasmosis and lymphoma. MATERIALS AND METHODS: We examined 11 AIDS patients, 6 with toxoplasmosis, 1 with a tuberculoma, and 4 with a primary CNS lymphoma. The FDG uptake within the lesion was compared with the uptake in a contralateral brain area [standardized uptake value (SUV)]. RESULTS: In all subjects with cerebral infections (toxoplasmosis, tuberculoma), the SUV ratio was significantly (p < 0.05) lower than the SUV ratio in patients with lymphoma (range of 0.3-0.7 vs. 1.7-3.1) with no overlap of the uptake values. CONCLUSION: In conclusion, FDG-PET may help to characterize these lesions metabolically and play an important role in the clinical management of AIDS patients with CNS involvement.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Parathyroid carcinoma: clinical aspects and therapy].

Parathyroid carcinoma is a rare entity with an 0,5-1% of incidence on primary hyperparathyroidism (HPP) in literature. The very high values of calcium and parathormone (PTH) and the clinical aspects of hypercalcemia are the characteristics findings in these patients. We present our experience on 6 pts on 153 cases with HPP treated (3,9%). The clinical and diagnostic suspects are frequently intraoperative findings and the decision making for the surgeon is not always easy (parathyroidectomy with or without hemithyroidectomy, lymphadenectomy, surgical resection of other tissues). The mortality rate is high and we have registered three deaths at 8,14 and 64 months.

Aged↗
PubMedDate not supplied

Evaluating the observable effects of foster grandparents on hospitalized children.

Because Foster Grandparent Programs have been widely implemented in acute care settings but not systematically evaluated, a study was done of the effects that the visiting of parent surrogates had on young children in acute care settings. Three groups of children in such settings were compared: those with foster grandparents, those without visitors, and those visited by their parents. Intergroup differences in the children's hospital behavior reached statistical significance in respect to only one of five behavioral domains investigated. The results of the foster grandparent intervention were found to be relatively weak compared with the results reported in earlier studies. However, it was believed that the discrepancy could be accounted for by the presence or absence of the visitor at the time of observation of the child's behavior. Implications drawn from the study were that greater benefits might be derived from the Foster Grandparent Program at little additional cost if the foster grandparent began visiting immediately upon the child's admission to the hospital, if this visiting extended beyond the current standard 2-hour period, and if the visitor was present at all traumatic medical procedures.

Child Behavior↗