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J Hafner

Publications and source records attributed to J Hafner.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Epstein-Barr virus genome positive lymphoepithelioma-like carcinoma of the stomach].

EBV is associated with a high number of tumours and non-tumourous conditions. The rare lymphoepithelioma like carcinoma of the stomach,--just as similar tumours of foregut origin (thymus, lung, salivary gland)--are frequently EBV genom positive with the expression of only a few genes (EBV nuclear antigen 1, EBV encoded ribonucleoproteins/EBER/, latency I). On the basis of the clinicopathological analysis of two cases and literature data the authors point out the male predominance and the relatively favourable prognosis of the patients, furthermore the frequent cardial-subcardial localization of these tumours. Since the frequent non-lymphoepithelioma like stomach tumours,--adenocarcinomas,--show EBV genom positivity in about 1% of the cases, it is concluded that the characteristic lymphoepithelioma like histological pattern is not a sine qua non condition of EBV genom positivity. It may also be assumed, that the CD8 and TIA 1 cytotoxic lymphocytes are not virus but tumour cell specific, however not efficient, perhaps not activated. The low level of apoptotic tumour cells supports this assumption. In one of the cases a double tumour, a genom positive lymphoepithelioma like carcinoma and a genom negative adenocarcinoma, adjacent to each other was seen which speaks in favour of common carcinogenetic factors and shows that microscopic neighbourhood is not a necessary condition in viral association. The origin of the possible oncogenic effect of EBV in the absence of the transforming gene products latent membrane protein 1 and EBNA 2 in genom positive stomach carcinomas is uncertain. The significance of the presence in both cases of CD 5+ tumour cells is not clear, the study of further cases is indicated.

Adult↗
PubMed2001

Coexistence of atomic and molecular chemisorption states: H(2)/Pd(210).

A novel H(2) molecular adsorption state on metal surfaces has been detected by temperature-programmed desorption and electron energy loss spectroscopy experiments of the H(2)/Pd(210) system. The molecular nature of this state has been verified by isotope exchange experiments. This molecular state leads to a decrease of the surface work function while atomic hydrogen on Pd(210) causes an increase. Ab initio total-energy calculations have confirmed all experimental findings. Through these calculations the microscopic nature of this novel molecular adsorption state could be identified; it turns out that this state is stabilized by the presence of atomic hydrogen on the Pd(210) surface.

Journal Article↗
PubMed2001

A periodic DFT study of intramolecular isomerization reactions of toluene and xylenes catalyzed by acidic mordenite.

A periodic density functional theory (DFT) study of the isomerization reactions of toluene and xylene catalyzed by acidic mordenite is reported. Monomolecular isomerization reactions have been considered and analyzed. The different reaction pathways have been discussed in detail. The use of periodic structure calculations allows consideration and analysis of zeolite electrostatic contributions and steric constraints that occur within zeolite micropores. Major differences in the details of protonation reaction pathways are found when periodic structures are used rather than small cluster models of the Brønsted acidic site. Complex relationships are found between zeolite topology and reaction pathways.

Journal Article↗
PubMed2001

Stability of Zn(II) cations in chabazite studied by periodical density functional theory.

The location of the Zn(2+) cation in Zn-exchanged chabazite has been studied by the periodical density functional method. Chabazite was chosen as a zeolite model, because it contains three different types of rings commonly found in the zeolite structures: four-, six-, and eight-membered rings. Two aluminum atoms have been employed to substitute the silicon atoms in the same D6R unit cell of the zeolite framework. This leads to different arrangements for the Brønsted site pair and the Zn(II) cation. The two Brønsted sites are found to be more stable when placed in the small ring (4T ring) than in the other rings. This suggests that the most reactive Brønsted sites are located in the large rings. Two Brønsted sites are most stable when the O(H)-Al-O-Si-O(H)-Al sequence is followed in the same ring instead of being located in two different rings. This resembles the aluminum distribution in the small four-membered ring and agrees with bond order conservation rules. The cation stability is markedly influenced by the distortions of the framework. Other factors that also contribute to the stabilization are the aluminum content near the cation and the stability of the original Brønsted sites. The Zn(2+) cation is more stable in the large rings than in the small ones, the six-membered one being the most stable configuration. In the small rings, the cation is, therefore, more reactive. Two different probe molecules have been used to study the interaction with the Zn(II) cation: water and methane. These probe molecules can extract the active center from its original position. For the water molecule, this effect is large and leads to a high framework relaxation. The value of the binding energy of this molecule to the active sites is influenced by these framework relaxations as well as by the cationic position environment. For weakly interacting methane, these effects are significantly less.

Journal Article↗
PubMed2001

A theoretical study of the alkylation reaction of toluene with methanol catalyzed by acidic mordenite.

A theoretical study of the alkylation reaction of toluene with methanol catalyzed by the acidic Mordenite (Si/Al = 23) is reported. Cluster DFT as well as periodical structure DFT calculations have been performed. Full reaction energy diagrams of the elementary reaction steps that lead to the formation of the three xylene isomers are given. The use of periodical structure calculations allows one to account for zeolite framework electrostatic contributions and steric constraints that take place in zeolitic catalysts. Especially the steric constraint energy contribution has a significant effect on the energies and bond formation paths. The activation energy barrier of p-xylene formation is found to be approximately 20 kJ/mol lower than the corresponding values for the formation of its isomers. Computed host-guest binding energies according to the DFT method need a correction due to the absence of the dispersive interaction with the zeolite wall. Apparent activation energies obtained with this correction are in good agreement with experimental data.

Journal Article↗
PubMed2001

[Conservative therapy in varicose symptom complex].

This article deals with the conservative management of light and severe forms of varicosities as well as chronic venous insufficiency along with subjective symptoms and trophic skin changes. Approximately 40% of the population shows minor forms and another 10% shows major forms of varicosities. The prevalence of advanced stages of chronic venous insufficiency is approximately 3%. Compression therapy represents the mainstay of anti-edema treatment. Elastic bandages are mainly used during the acute phase, and compression stockings are rather recommended to maintain the result. The differences of short stretch and long stretch bandages, as well as the classes of compression therapy are discussed. Physical therapy, such as joint mobilization, ambulation exercises, and lymph drainage may further support edema reduction in severe cases. Edema-protective drugs can be justified as adjuvant treatment. The pharmacology and action of these substances has been further elucidated by both laboratory and clinical studies. It has been shown that the continuous use of these substances during 8-12 weeks can reach the anti-edematous effect of class II-stockings. Sclerotherapy is especially useful in the treatment of smaller caliper reticular varicosities and teleangiectatic veins. The development of new vascular lasers with a long pulse duration has added to the options in the treatment of leg teleangiectasias, although these expensive techniques cannot be regarded a standard therapy. Advanced stages of chronic venous insufficiency are also amenable to conservative treatment. In these cases, an exact vascular examination is highly recommended. Interventional treatment of relevant peripheral arterial disease and of superficial venous insufficiency can impressively improve the quality of life of these patients, even at an elderly age. Moreover, the role and differential indication of synthetic dressings in the local therapy of chronic leg ulcers is explained in-depth.

Bandages↗
PubMed2001

[Case report on therapy with granulocyte stimulating factor in diabetic foot].

Several pathogenetic factors such as peripheral neuropathy, vasculopathy and infection are responsible for the development of diabetic foot ulcerations. An important factor contributing to the high infection risk in diabetic patients is a defect in neutrophil granulocytes. Deficiencies in neutrophil chemotaxis, phagocytosis and respiratory burst activity with the decrease of the super- and peroxids are known to be associated with diabetes. Granulocyte-colony stimulating factor (G-CSF) increases the release of neutrophils from the bone marrow and improves neutrophil function. A 78-year old patient with non-insulin-dependent diabetes presented with ulcerations of both big toes and a malum perforans on the right sole. He also had generalized arteriosclerosis as well as a polyneuropathy with a dry foot and typical foot deformation as well as decreased in sensitivity. Intensive local care for 35 days led to no improvement of the ulcerations. Then G-CSF (Neupogen) was administered in a total dose of 165 million IU over 11 days; the daily dose varied between 15-30 million IU depending on the absolute leucocyte count. In addition 500 mg of oral ciprofloxacin (Ciproxin) was given b.i.d. This treatment led to a significant improvement of the lesions. Within 11 days cost analysis suggests G-CSF may be a cost-effective addition to antimicrobial therapy in diabetic foot infection.

Aged↗
PubMed2001

Skin cancers in organ transplant recipients: two cases of virus-induced neoplasms.

Immunosuppression profoundly influences the prevalence of skin disorders in transplant recipients. Skin tumors occur with high incidence and constitute a major part of transplantation-related morbidity and mortality. We report on 2 immunosuppressed patients presenting with rapidly growing epithelial and mesenchymal neoplasms after renal transplantation. The diagnostic approach, differential diagnosis and treatment options are discussed emphasizing the characteristics of cutaneous lesions in immunosuppressed transplant recipients.

Adult↗
PubMed2001

Factor V Leiden mutation in postthrombotic and non-postthrombotic venous ulcers.

OBJECTIVE: To determine the prevalence of the factor V Leiden mutation in patients with postthrombotic and non-postthrombotic venous ulcers. DESIGN: Case-control study. SETTING: Department of Dermatology, University Hospital of Zurich, Zurich, Switzerland. PARTICIPANTS: Seventy-three consecutive outpatients and inpatients with venous ulcers and 45 age- and sex-matched control subjects (matched to the 42 patients with postthrombotic syndrome). MAIN OUTCOME MEASURES: Frequency of postthrombotic and non-postthrombotic findings in patients with venous ulcers. Prevalence of the factor V Leiden mutation in these different subgroups. RESULTS: Postthrombotic syndrome was identified as the cause of 42 (58%; 95% confidence interval [CI], 45%-69%) of 73 venous ulcers, and the remainder were caused by primary valvular insufficiency. In postthrombotic ulcers, the prevalence of the factor V Leiden mutation was 38% (95% CI, 24%-54%) (16/42), which corresponds to an odds ratio of 13.2 (95% CI, 2.8-62.3; P<.001). In non-postthrombotic venous ulcers, the prevalence was 16% (95% CI, 5%-34%) (5/31), which corresponds to an odds ratio of 3.2 (95% CI, 1.0-10.0; P =.07). CONCLUSIONS: The factor V Leiden mutation is highly prevalent in patients with postthrombotic venous ulcers. Even patients with non-postthrombotic venous ulcers show a moderately elevated prevalence of the factor V Leiden mutation. Some of the latter might be misclassified because of near-to-perfect revascularization after asymptomatic deep venous thrombosis. However, as long as the therapeutic consequences of the factor V Leiden mutation are not established, systematic screening cannot be recommended in patients with venous ulcers.

Aged↗
PubMed2000

[CO2-laser therapy of stigmatizing cutaneous lesions in tuberous sclerosis (Bourneville-Pringle) and in neurofibromatosis 1 (von Recklinghausen)].

Tuberous sclerosis (Bourneville-Pringle) and type I neurofibromatosis (von Recklinghausen) are familial multiple tumour syndromes. Both entities have in common that the cutaneous manifestations can stigmatize the carriers and considerably reduce the quality of life. CO2-laser surgery (vaporisation) consistently yields good to excellent aesthetic results in the treatment of adenoma sebaceum in tuberous sclerosis. Patients with type I neurofibromatosis who carry several hundreds neurofibromas usually benefit from a numerical reduction in their skin lesions, despite the less predictable aesthetic result, ranging from excellent to fair. The present study reports on the treatment outcome of CO2-laser surgery in 8 patients with adenoma sebaceum and 8 with neurofibromatosis.

Adolescent↗
PubMed2000

[Castleman's disease].

Castleman's disease is an example of the so-called atypical lymphoproliferative disorders. The optimal therapy of this morphologically and clinically heterogeneous disease is largely unknown. The authors report three cases of multicentric Castleman's disease (two hyalin vascular and one mixed variant). They analyze the pathogenesis, clinicopathologic features and management of this rare entity and review the literature.

Aged↗
PubMed2000

A comparison of multilayer bandage systems during rest, exercise, and over 2 days of wear time.

OBJECTIVE: To study the interface pressure between the leg and 8 different multilayer bandage systems during postural changes, exercise (walking), and over 2 days of wear time. DESIGN: Comparison of 8 different compression bandages under standardized conditions. SETTING: Department of Dermatology, University Hospital of Zurich, Zurich, Switzerland. PARTICIPANTS: A series of 10 healthy volunteers, 5 females and 5 males, aged 26 to 65 years. INTERVENTION: An electropneumatic device was used to measure interface pressure at 12 points of the leg. MAIN OUTCOME MEASURES: (1) Pressure changes from the standing to the sitting and supine position at rest, (2) pressure amplitude during exercise (200-m treadmill walk at 3.2 m/s, 0 degrees incline), and (3) pressure decrease over 2 days of wear time. RESULTS: Results are given as median with the 10% to 90% confidence intervals. Multilayer bandages of short and medium stretch showed a larger pressure decrease when the patient was supine (eg, 3 short stretch bandages: 18.0 mm Hg [reference range, 15.5-19.5 mm Hg]) than systems of medium and long stretch bandages (eg, 4-layer bandage, 6.0 mm Hg [reference range, 4.5-7.0 mm Hg]) (P=.005). The amplitude of pressure waves during exercise was comparable among most multilayer bandage systems. The pressure loss over time was the smallest in elastic bandages (eg, 4-layer bandage, 6.0 mm Hg [reference range, 0.0-10.5 mm Hg]), compared with short stretch bandages (eg, 3 short stretch bandages, 18.0 mm Hg [reference range, 16.5-20.5 mm Hg]) (P=.005). CONCLUSIONS: Highly elastic multilayer bandage systems showed the smallest pressure loss over several days, but the small pressure decrease when the patient was supine makes them potentially hazardous to patients with arterial occlusive disease. Short stretch bandages and the Unna boot with an inelastic zinc plaster bandage generate large pressure waves while walking and showed a marked pressure decrease when the patient was supine, but they lose a lot of their pressure within the first hours of wear. Multilayer systems composed of short stretch and cohesive medium stretch bandages represent a good compromise between elastic and inelastic bandage systems (moderate pressure loss over time, large pressure decrease on lying down). The clinical effectiveness of the different types of compression still remains to be studied.

Adult↗
PubMed2000

Instruction of compression therapy by means of interface pressure measurement.

BACKGROUND: Compression therapy of the leg is the cornerstone in the conservative treatment of venous ulcers. The application of compression bandages, however, is largely a matter of personal experience. OBJECTIVE: To evaluate the interface pressure under compression bandages and to improve the technique. METHODS: Six courses on wound healing with 24-28 participants as well as individual training at our hospital were provided. Interface pressure at the distal medial calf was measured using a simple, but accurate pressure sensor that was built for this purpose (accuracy: +/-3 mm Hg). RESULTS: During the wound healing courses, the absolute difference from the target pressure of 35-45 mmHg improved from 8.4 mm Hg (95% CI 0.0-34.1) to 3.5 mm Hg (95% CI 0.0-14.0) (P = .0001). After four sessions, interface pressures greater than 60 mmHg were avoided. During individual training, even nurses with everyday experience in compression therapy improved their accuracy. CONCLUSION: There is a need for objective measurement of interface pressure in the teaching of compression therapy with bandages. The principles can be taught during a few exercises. However, repeated practice over a longer period of time is necessary to reach a certain accuracy.

Bandages↗
PubMed2000

Leg ulcers in peripheral arterial disease (arterial leg ulcers): impaired wound healing above the threshold of chronic critical limb ischemia.

BACKGROUND: Peripheral arterial disease is the only identifiable etiology in approximately 10% of leg ulcers. Clinical data on the management of these chronic wounds are scarce. OBJECTIVE: We attempted to outline the threshold of systolic ankle pressure and ankle-brachial-index (ABI) below which arterial leg ulcers can occur and to outline the indication for revascularization in arterial leg ulcers. METHODS: Diagnostic and outcome analysis was performed for 26 consecutive patients with arterial leg ulcers. We calculated sensitivities, specificities, and receiver operating characteristic (ROC) curves for the identification of arterial leg ulcers among all 223 consecutive leg ulcer patients within a 3-year period, as well as the ROC curve for patients who required revascularization. RESULTS: The systolic ankle pressure was 88 (18-130) mm Hg (median; 95% confidence interval) and the ABI was 0.60 (0.15-0.86), respectively. Eighteen patients (69%) were subjected to revascularization. By the end of the study, 24 patients (92%) healed completely, 1 improved (90% wound closure), and 1 patient had to undergo below-knee amputation for chronic osteomyelitis. During this study, the ankle pressure and ABI were poor in distinguishing those patients who required revascularization from those who healed without revascularization. CONCLUSION: Most arterial leg ulcers do not meet the criteria of chronic critical limb ischemia, but they do not heal under conservative measures, either. A majority of these patients benefit from revascularization and should, therefore, be referred for arterial duplex ultrasound investigation or angiography. In our study, an ankle pressure below 110 mm Hg identified all patients (100%) who were subjected to revascularization procedures. However, controlled clinical studies are required to find the systolic ankle pressure and ABI below which revascularization can be recommended to speed up the healing time.

Aged↗
PubMed2000

Management of leg ulcers in patients with rheumatoid arthritis or systemic sclerosis: the importance of concomitant arterial and venous disease.

PURPOSE: We assessed the etiology and the prevalence of peripheral arterial and venous disease in leg ulcers in patients with rheumatoid arthritis and systemic sclerosis and analyzed the outcome after treatment of macrovascular disease. METHODS: A clinical study on 15 consecutive patients with chronic leg ulcers in collagen vascular disease (nine patients with rheumatoid arthritis, six patients with systemic sclerosis) was carried out in a referral center. Angiography was used when the ankle-arm index was less than 0.8; venography was used when venous reflux was detectable by means of a hand-held Doppler examination. Therapies included percutaneous transluminal angioplasty (seven patients), femoropopliteal bypass grafting surgery (one patient), saphenectomy of the greater saphenous vein (six patients), and split skin graft (11 patients). RESULTS: All patients with rheumatoid arthritis exhibited a multifactorial etiology of their ulcers: four of nine patients had peripheral arterial disease, and five of nine patients had venous insufficiency. In one of these patients, arterial and venous disease was combined. Five of six patients with systemic sclerosis exhibited a multifactorial etiology of their ulcers: three of six patients had peripheral arterial disease, and three of six patients had venous insufficiency. One of these patients had both arterial and venous disease. In patients with rheumatoid arthritis, healing was achieved in six of nine patients, and marked improvement occurred in two of nine patients. A below-knee amputation was necessary in one patient with rheumatoid vasculitis. In patients with systemic sclerosis, healing was achieved in three of six patients, and marked improvement occurred in the other three patients. CONCLUSION: Most leg ulcers in patients with rheumatoid arthritis and systemic sclerosis disclose a multifactorial etiology. Relevant arterial and venous disease can be found in approximately half the patients. Our study suggests that revascularization and vein surgery improve the healing of leg ulcers in patients with collagen vascular disease. A prospective trial is now required to confirm these results.

Aged↗