Biomedical subjects

G Wolf

Publications and source records attributed to G Wolf.

At least 55 records · Page 3Linked to original sources

PubMed2003

Pathology results in [18F]fluorodeoxyglucose positron emission tomography of the thyroid gland.

The aim of this retrospective study was to evaluate pathologically increased uptake of [18F]fluorodeoxyglucose (18F-FDG) in positron emission tomography (PET) results of the thyroid gland. Results of 18F-FDG PET and [99mTc]pertechnetate scintigraphy of the thyroid gland are shown, compared to each other and discussed. In a retrospective study 16 patients underwent whole-body 18F-FDG PET and [99mTc]pertechnetate scintigraphy of the thyroid gland within 3 weeks. In addition, an examination of the thyroid gland by using ultrasound and laboratory tests was carried out. The 18F-FDG PET studies were carried out on a dedicated whole-ring PET scanner. Eight patients had a pathological FDG uptake in the thyroid and a cold nodule in [99mTc]pertechnetate scintigraphy of the thyroid gland (in 7/8 cases histology showed malignancy). Five patients had an inhomogeneous FDG uptake in the thyroid gland and were suspected of thyroiditis in 18F-FDG PET (in 3/5 cases thyroiditis was confirmed). Three patients had an especially low FDG uptake compared to normal physiological FDG uptake (no malignancy). Results from studies using 18F-FDG represent a growing body of evidence showing the differentiation between malignant and benign disease: we saw many pathological results in the thyroid gland. High uptake of 18F-FDG in the thyroid gland suggests possible malignancy. Thyroiditis can only be suspected based upon the results of 18F-FDG PET. We conclude that 18F-FDG PET has a potential clinical impact for detecting possible malignant lesions of the thyroid gland, but further studies, in which a higher number of patients are evaluated, are necessary.

Adolescent↗

PubMed2003

Diagnosis of a contralateral second testicular carcinoma by F18-FDG PET.

BACKGROUND: In testicular carcinoma the early diagnosis is very important because with an early therapy there are good chances for long-term survival (50-90%). Metastases of a testicular carcinoma are at first lymphogenous, hematogenous only in late stages. CASE REPORT: This is a case report about a 28-year-old man, whose testicular carcinoma (left testis) had already been operated on (unripe teratoma with parts of an embryonic carcinoma, an endodermal sinus tumor and a chorion carcinoma). Because of the elevated tumor marker AFP an FDG PET (F18-fluorodeoxyglucose positron emission tomography) investigation was made. CT (covering thorax, abdomen and pelvis) and ultrasound of the testis showed no pathological results. In the FDG PET a significant pathological FDG uptake in the right testis was found. Histology showed an unripe teratoma with parts of an embryonic carcinoma, an endodermal sinus tumor, and a chorion carcinoma. It was a second carcinoma of the contralateral testis. CONCLUSION: F18-FDG PET was a sensitive and reliable modality for diagnosis in this patient.

Adult↗

PubMed2003

Monitoring of biofilm reactors using natural fluorescence fingerprints.

Natural fluorescence as a method to monitor biofilm processes was studied, using the example of an extractive membrane bioreactor for the degradation of 3-chloro-4 methylaniline and 1,2-dichloroethane. Non-invasive, on-line, in-situ 2D fluorometry monitoring was employed to elicit biofilm process status. The fluorescence fingerprints were deconvoluted in a pattern recognition approach using artificial neural networks (ANN) through association with key process performance parameters.

Biofilms↗

PubMed2003

18F-FDG PET: early postoperative period of oro-maxillo-facial flaps.

AIM: We addressed the feasibility of FDG-PET to differentiate between viability and non-viability in the immediate postoperative assessment of flaps (autologous microvascular anastomosed pedicled flaps) in oro-maxillo-facial surgery. METHODS: 3-7 days after surgery, FDG-PET was done in 38 patients who had received flaps for re-construction of the mandible after partial resection. The studies were done on a dedicated full ring PET-scanner (ECAT EXACT HR+, Siemens/CTI). Acquisition started between 60 and 80 min post injection. The findings of the soft tissue component of the flaps were grouped using a three point scale: (I) no defect, (II) small defects, (III) one large defect. The results of PET were compared with the clinical course for at least 3 months. RESULTS: "No defect" on the FDG-PET study identified vi-ability of the flap and predicted normal clinical follow-up (22/38 patients). "Small defects" visualized areas of decreased perfusion and decreased glucose metabolism indicating risk of non-viability (13/38 patients); adapt-ing the postsurgical management led to delayed but uncomplicated healing of the flaps in these patients. "One large defect" demonstrated early necrosis of the flap (3/38 patients). After removal and replacement of this necrotic portion of the flap the second FDG-PET scan of these 3 patients demonstrated the uncomplicated post-operative healing. CONCLUSION: FDG-PET facilitated the assessment of viability and non viability of flaps in the immediate postsurgical period, and demonstrated the usefulness of FDG-PET for postoperative care and prognosis.

Adult↗

PubMed2003

Nitric oxide synthase, an essential factor in peripheral nerve regeneration.

Nitric oxide (NO) exerts both, pro-apoptotic and anti-apoptotic actions and appears to be acritical factor inneuronal degenerative and regenerative processes. NO is synthesized from L-arginine by NO synthase occurring in three isoforms of (neuronal, nNOS; endothelial, eNOS; inducible, iNOS). In a mice sciatic nerve model the regenerative outcome was assessed when the endogenous NO supply was deficient by knocking out the respective NOS isoform and compared to that of wild type mice after nerve transection. In nNOS knock-out mice a delay in regeneration, preceded by slowedWallerian degeneration and a disturbed pruning of uncontrolled sprouts, was observed. This was associated with a delayed recovery of sensory and motor function. Additionally, deficiency of nNOS led after nerve cut to a substantial loss of small and medium-sized dorsal root ganglia neurons, spinal cord interneurons and, to a lesser extent, spinal cord motor neurons. A lack of iNOS resulted in a delayed Wallerian degeneration and impaired regenerative outcome without consequences for neuronal survival. A lack of eNOS was well tolerated, although a delay in nerve revascularization was observed. Thus, after peripheral nerve lesion, regular NOS activity is essential for cell survival and recovery with reference to the nNOS isoform.

Animals↗

PubMed2002

Oxidative and nitrosative stress induces peroxiredoxins in pancreatic beta cells.

AIMS/HYPOTHESIS: Insulin-producing beta cells are destroyed by oxidative and nitrosative stress during the pathogenesis of Type I (insulin-dependent) diabetes mellitus. These cells are more sensitive than others due to their deficiency of well known antioxidant enzymes like superoxide dismutase, glutathione peroxidase and catalase. However the peroxiredoxins discovered in the past decade form a large family of highly conserved thioredoxin-dependent peroxide reductases, which are present in most tissues. We investigated whether peroxiredoxins I and II are present in pancreatic beta cells and if they are inducible by oxidative and nitrosative stress. METHODS: To detect these enzymes in insulin-producing beta cells we used semiquantitative RT-PCR, western blots and immunohistochemistry. The expression of peroxiredoxins I and II was analysed after treatment with cytokines, hydrogen peroxide, alloxan or streptozotocin in the rat insulinoma cells INS-1 using RT-PCR and western blots. RESULTS: We show that peroxiredoxins I and II are present in the cytoplasm of pancreatic islet cells as well as in insulinoma cell lines beta TC6-F7 and INS-1. Peroxiredoxins I and II were up-regulated by all stress agents used. CONCLUSION/INTERPRETATION: Beta cells, undersupplied with well characterized antioxidant enzymes, possess an additional antioxidant system which is inducible by oxidative as well as nitrosative stress.

Animals↗

PubMed2002

The neuron-specific Ca2+-binding protein caldendrin: gene structure, splice isoforms, and expression in the rat central nervous system.

Caldendrin is the founder member of a recently discovered family of calmodulin-like proteins, which are highly abundant in brain. In this study we examined the organization of the murine and human caldendrin gene as well as the expression pattern of transcripts for caldendrin and two novel splice variants. In addition the distribution of caldendrin in rat brain has been assessed by immunohistochemistry. Caldendrin is localized to the somatodendritic compartment of a subpopulation of mainly principal neurons in brain regions with a laminar organization and is present only at a subset of mature excitatory synapses. Caldendrin immunoreactivity (IR) is tightly associated with the cortical cytoskeleton, enriched in the postsynaptic density (PSD) fraction, and associates late during development with the synaptic cytomatrix. The expression is highly heterogenous within cortex, with highest levels of caldendrin IR in layer III of the piriform and layer II/III of the somatosensory cortex. The segregated cortical distribution to areas, which represent the most important primary sensory systems of the rodent brain, may reflect different requirements for dendritic Ca2+-signaling in these neurons. The presence of caldendrin in the PSD of distinct synapses may have important implications for Ca2+-modulated processes of synaptic plasticity.

Alternative Splicing↗

PubMed2002

[Diagnosis of metastasis of malignant melanoma in the thyroid gland with f18-FDG PET scan].

Metastases in the thyroid gland are very rare. When they occur, long-term survival is dismal; thus an early diagnosis is critical. Malignant melanoma is one of the tumors which may metastasize to the thyroid gland. Therefore we wanted to demonstrate F18-Fluorodeoxyglucose-Positron emission tomography (F18-FDG-PET) is a sensitive and reliable method to identify such metastases. We report about a 51-year-old man, who had an inguinal lymph node metastasis of a malignant melanoma with unknown primary tumor site. He came to us for an a follow-up F18-FDG-PET investigation. In the PET there was a pathologic FDG-uptake in the left lobe of the thyroid gland. The nodule was removed and showed a malignant melanoma metastasis. This unusual scenario underscores the value of the PET in the oncologic follow-up of patients with malignant melanoma.

Diagnosis, Differential↗

PubMed2002

Strain specific differences in a cardio-pulmonary resuscitation rat model.

An asphyxial cardiac arrest rat model, originally developed for Sprague-Dawley rats, was transferred to a Wistar rat model. Several strain specific life support adjustments, i.e. ventilator settings, anaesthesia, and drug requirements, were necessary to stabilize the model for Wistar rats. Despite these arrangements numerous resuscitation related variables appeared different. Three groups were evaluated and compared: a temperature monitored Wistar group 1 (n=34), a temperature controlled Wistar group 2 (n=26) and a temperature controlled Sprague-Dawley group 3 (n=7). Overall, Wistar rats seem to have more sensitive cardio-circulatory system evidenced by a more rapid development of cardiac arrest (164 vs. 201 s), requiring higher adrenaline/epinephrine doses (10 vs. 5 microg/kg) and requiring more time for recovery after resuscitation (i.e. for return of blood pressure and blood gases). Without strict temperature control (as in groups 2+3 rats) group 1 rats went into spontaneous mild to moderate hypothermia during the first 24 h after restoration of spontaneous circulation (ROSC). Spontaneous hypothermia delayed the development of overall visible CA1 neuronal damage 24-48 h, but did not prevent it; therefore the model seemed to be suitable for future studies. Neuronal damages in the CA1 region in Wistar rats appeared to be more as shrunken cell bodies and pyknotic nuclei before resorption took place, whereas in Sprague-Dawley rats appeared in the same region.

Animals↗

PubMed2002

Phylogenetic analysis of the 5'-untranslated region of german BVDV type II isolates.

On the basis of genetic differences, bovine viral diarrhoea viruses (BVDV) are subclassified into two distinct genotypes, BVDV type I and BVDV type II. We selected German BVDV type II isolates using the BVDV type I-specific monoclonal antibody WB160 and flow cytometric analysis for further characterization. For molecular characterization, a 288-bp fragment of the 5'-untranslated region (5'-UTR) of the selected isolates was investigated by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing. Sequence comparisons of the partial 5'-UTR sequences and their phylogenetic analyses demonstrated that the 18 German BVDV type II isolates all belong to either subtype IIa (10 isolates) or subtype IIc (eight isolates). Nevertheless, the German BVDV type II isolates were genetically different (89.9-94.3% sequence identity) from the standard BVDV type II strain 890 from North America, which was recently classified as BVDV type IIa. Furthermore, a clear subdivision of the German BVDV type II isolates into two distinct subtypes (BVDV IIa Germany and BVDV IIc Germany) is shown. Viruses of both subgroups differed in the analysed 5'-UTR fragment from each other (91.6-95.2% sequence identity), but were highly conserved within the same German subtype (97.2-100% sequence identity). These findings are discussed in the context of BVDV type II origin, possible introduction into Germany, its epidemiology and impact for vaccine development.

5' Untranslated Regions↗

PubMed2002

Escherichia coli isolates from young calves in Bavaria: in vitro susceptibilities to 14 anti-microbial agents.

During the occasional testing of Escherichia coli from faecal samples of young calves we observed multi-resistant isolates. Because of the significance of E. coli as an indicator bacterium for resistance trends we tested E. coli populations of young calves over a longer period. Here we present the results of a retrospective study comparing isolates from 1998 to 2000. Moreover, we compared, in a clinical study, the resistance rates of E. coli populations from 67 hospitalized calves both before and after hospitalization (with or without anti-microbial therapy), and with their anamnestic data of antibiotic usage. The highest resistance rates were found to be more than 80% for tetracyclines, ampicillin, sulfonamide/trimethoprim combinations, and chloramphenicol. A significant increase or decrease over the years was not observed. In analysing the data of hospitalized calves, an increase of resistance to some anti-microbials had to be registered that seemed to be connected with the selective pressure due to agents used in the clinic. In comparing anamnestic data and resistance rates it became obvious that reliable data are not easily available and that a number of potential anti-microbial influence factors have to be taken into account.

Animals↗

PubMed2002

[Renal cell carcinoma metastasis in a microfollicular adenoma of the thyroid gland].

A 60-year-old woman had a nephrectomy of her left kidney because of a renal cell carcinoma. She came to us for an oncologic F-18-fluordeoxyglucose-positron emission tomography (F-18-FDG-PET). In the positron emission tomography there was a pathologic fluordeoxyglucose-uptake in the left thyroid gland lobe. Thyroid investigation and Tc-99 m pertechnetate scintigraphy of the thyroid gland was done. It showed a hyperfunctioning nodule in the left thyroid gland lobe. Surgery was suggested. Histology showed a metastasis of a clear cell renal carcinoma in a microfollicular adenoma of the thyroid gland--a very rare combination.

Adenoma↗

PubMed2002

Radiation-induced apoptosis in human non-small-cell lung cancer cell lines is secondary to cell-cycle progression beyond the G2-phase checkpoint.

PURPOSE: To characterize the relationship between cell-cycle progression and radiation-induced apoptosis in NSCLC cell lines with different p53 status. MATERIALS AND METHODS: Cell lines with functional (H460, A549) and non-functional p53 (H661 and H520) were irradiated with 20 Gy. Multiparameter flow-cytometry was used to follow the progression of synchronized cells through the cell cycle after irradiation. RESULTS: Delayed apoptosis was observed after cell-cycle progression beyond the G2 block, either in the late G2/M-phase of the same cell cycle being irradiated (H661, H520) or in the G1-phase of the subsequent cell cycle (H460, A549). The apoptotic fraction in H661 and H520 was 60-80% at 144h after irradiation, higher than in A549 and H460 (5 and 35%, respectively). As an alternative to apoptosis in cells cycling beyond the G2 restriction point, hyperploid cells were generated by all cell lines. Inhibition of cell-cycle progression through the G2/M-phase efficiently reduced the induction of late apoptosis. After irradiation in S-phase, 50-60% of cells with functional p53 remained arrested at the G2 restriction point until 144 h post-irradiation, while only 20% of the H661 or H520 did so. CONCLUSIONS: These data characterize radiation-induced apoptosis in NSCLC cell lines as a removal pathway of clonogenically inactivated cells secondary to cell-cycle progression beyond G2/M, and is unlikely to be a critical factor for cellular radiation sensitivity.

Apoptosis↗

PubMed2002

Seminoma metastases mimicking primary pancreatic cancer.

BACKGROUND: A case of seminoma clinical stage III, arising from the right testis and mimicking a primary pancreatic malignancy is reported. CASE REPORT: A 57-year-old male patient presented with obstructive jaundice. He suffered from recurrent abdominal pain and significant weight loss over the past 4 months. Abdominal CT scan showed a tumor in the head of the pancreas and multiple pathologically enlarged peripancreatic lymph nodes. In the laboratory findings there were signs of cholestasis and infection. A laparoscopic biopsy out of a suspicious lesion of the head of the pancreas and a surrounding lymph node was done. Histopathological examination reported metastasis of seminoma in a lymph node. Further laboratory findings showed an elevation of the human placental alkaline phosphatase (HPLAP) and urological examination revealed a suspect right testis. The patient underwent castration of the right testis and histopathological examination confirmed a seminoma. 4 cycles of chemotherapy including cisplatinum, etoposide and bleomycin led into complete response that is still ongoing. CONCLUSION: This case shows a seminoma with metastases at retroperitoneal site, mimicking a primary pancreatic neoplasm. It provides an example of the possibility of an uncommon clinical appearance of seminoma metastases and again underlines the importance of exact radiological and histopathological examination to distinguish between curable and incurable tumor.

Biopsy↗

PubMed2002

Combination of surgery and gamma knife radiosurgery--a therapeutic option for patients with tumors of nasal cavity or paranasal sinuses infiltrating the skull base.

UNLABELLED: The purpose of this study was to investigate whether patients operated for skull base-infiltrating malignant tumors of the nasal cavity and/or the paranasal sinuses benefit from an additional Gamma knife radiosurgery. CASE SERIES: eight consecutive patients, (male: female ratio = 1:1, mean age = 52 years, range 34 to 79 years) presented with 2 cyclindric cell carcinomas, 2 adenocarcinomas, 2 malignant neuroblastomas, 1 squamous cell carcinoma, 1 amelanotic melanoma. Tumor stages (UICC) were: 1 T1, 3 T2, 3 T3, 1 T4, all N0, all M0. All patients were primarily treated surgically and 4 weeks later received additional stereotactic radiosurgery. Follow-up was based on computerized tomography (CT), magnetic resonance imaging (MRI), endoscopy, and biopsy. The course of disease was compared to tumor courses with surgery but without radiosurgery reported in literature. Four times endoscopic endonasal surgery (EES), once EES in combination with fluorescein technique, once EES plus external approach of frontal sinus, once lateral rhinotomy was performed. All 8 cases underwent radiosurgery (Leksell gamma knife) 4 weeks after surgery. Thirty six months after radiosurgery 6 patients were alive (4 patients without evidence of disease, 1 patient with pulmonary metastasis but without local recurrence, 1 patient with regional metastasis but no local recurrence), 1 patient died 11 months after treatment due to disease, 1 patient died due to a second malignancy. No negative or adverse effects due to radiosurgery were observed. The combination of microsurgery with Leksell Gamma knife radiosurgery appears to be an encouraging therapeutic option. To date no adverse effects have been observed in the presented cases.

Adult↗

PubMed2001

A pilot study of hormone replacement therapy with tibolone in women with mastopathic breasts.

OBJECTIVE: Our purpose was to investigate the effect of tibolone in a prospective randomized, double-blind pilot study in postmenopausal women with clinically palpable mastopathic changes. METHODS: Twenty postmenopausal non-users of hormone replacement therapy undergoing mammography were randomly allocated to receive either 2.5 mg tibolone (Livial, Organon) or placebo (2 mg lactose). Mammographic density according to the Wolfe classification, severity of breast discomfort, parity, smoking habits, body weight and follicle-stimulating hormone (FSH) and estradiol (E(2)) levels were documented at baseline and after 6 months of treatment. RESULTS: There were no statistically significant differences between the two treatment groups in terms of parity, smoking, body weight and FSH and E(2) levels. At 6 months, four patients in the tibolone group showed reduced breast density, compared with one patient in the placebo group. Whereas no significant differences were found between the two treatment groups when the categories 'minimal reduction' and 'reduction' in mammographic density were combined, combination of the categories 'no change' and 'minimal reduction' showed a significant difference (P<0.036). Also, women in the tibolone group showed a statistically significant improvement in breast discomfort (P<0.019). CONCLUSION: This pilot study showed decreases in breast density as well as an attendant significant alleviation of breast discomfort in women with baseline mastopathic changes treated with tibolone for 6 months, which may be due to the inhibitory effect of tibolone on the enzymes involved in the biosynthesis of estradiol demonstrated in previous trials and should be further evaluated in long-term studies.

Breast↗

PubMed2001

Intraductal papillary-mucinous tumors of the pancreas: presentation of eight cases.

BACKGROUND AND STUDY AIMS: The mucinsecreting intraductal papillary-mucinous tumors of the pancreas are a rare entity with characteristic duodenoscopic and radiological features. These tumors have a broad spectrum of presentation. The diagnosis requires highly experienced and attentive endoscopists. Once diagnosed, resection of the tumor is recommended to prevent progression to malignancy. This surgical procedure has a low acceptance, mainly in the elderly patients. Therefore, a "wait and see" strategy may be necessary in those patients refusing operation. PATIENTS AND METHODS: Between 1996 and 2000, intraductal papillary-mucinous tumors of the pancreas were diagnosed in eight patients (5 females, 3 males) using endoscopic retrograde cholangiopancreatography, and confirmed by brush cytology and/or histology and analyzed retrospectively. RESULTS: The patients showed typical endoscopic and radiological findings: dilatation and mucin extrusion of the papillary orifice, easy passage of instruments into the dilated main pancreatic duct, which showed patchy filling defects after application of contrast medium. Patients were informed about the diagnosis in detail. Two patients were inoperable. Surgery was recommended to the other six patients. Two of the six patients agreed to surgical treatment. The remaining four patients were included in a follow-up protocol. These patients were observed for up to 5 years. Only one patient showed minor progression of ERCP-findings. CONCLUSION: Intraductal papillary-mucinous tumors of the pancreas can be well characterized by means of endoscopy and radiology. Poor compliance to surgical treatment makes individual multidisciplinary management and follow-up necessary.

Adenocarcinoma, Mucinous↗

PubMed2001

Synthesis of silicon-based infrared semiconductors in the Ge-Sn system using molecular chemistry methods.

Growth reactions based on a newly developed deuterium-stabilized Sn hydride [(Ph)SnD(3)] with Ge(2)H(6) produce a new family of Ge-Sn semiconductors with tunable band gaps and potential applications in high-speed, high-efficiency infrared optoelectronics. Metastable diamond-cubic films of Ge(1-x)Sn(x) alloys are created by chemical vapor deposition at 350 degrees C on Si(100). These exhibit unprecedented thermal stability and superior crystallinity despite the 17% lattice mismatch between the constituent materials. The composition, crystal structure, electronic structure, and optical properties of these materials are characterized by Rutherford backscattering, high-resolution electron microscopy, and X-ray diffraction, as well as Raman, IR, and spectroscopic ellipsometry. Electron diffraction reveals monocrystalline and perfectly epitaxial layers with lattice constants intermediate between those of Ge and alpha-Sn. X-ray diffraction in the theta-2theta mode shows well-defined peaks corresponding to random alloys, and in-plane rocking scans of the (004) reflection confirm a tightly aligned spread of the crystal mosaics. RBS ion-channeling including angular scans confirm that Sn occupies substitutional lattice sites and also provide evidence of local ordering of the elements with increasing Sn concentration. The Raman spectra show bands corresponding to Ge-Ge and Sn-Ge vibrations with frequencies consistent with random tetrahedral alloys. Resonance Raman and ellipsometry spectra indicate a band-gap reduction relative to Ge. The IR transmission spectra suggest that the band gap decreases monotonically with increasing Sn fraction. The synthesis, characterization, and gas-phase electron diffraction structure of (Ph)SnD(3) are also reported.

Journal Article↗