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Biomedical subjects

K Hoffmann

Publications and source records attributed to K Hoffmann.

At least 109 records · Page 6Linked to original sources
PubMed2000

Macroangiopathy of the upper extremities in progressive systemic sclerosis.

BACKGROUND: Raynaud's phenomenon is a hallmark of progressive systemic sclerosis (SSc). While nailfold capillary changes are well known, morphological changes in larger arteries have less been focused on. OBJECTIVE AND METHODS: In the study presented we examined how often in digital subtraction angiography organic changes of the arteries of the fingers, hands and forearms were observed, whether they showed a typical picture like the changes in nailfold capillaries and whether they correlated with cutaneous sclerosis, Raynaud's phenomenon and serological findings. 29 patients were examined, 14 with acroscleroderma and 15 with proximal ascending sclerosis. RESULTS: In 27 of those 29 patients a stenosis of the arteries of the upper extremity was found. The frequency of arterial occlusions decreased from the fingers (26 patients) to the forearms (9 patients with occlusion of the ulnar artery, none with occlusion of the radial artery). The arteries of 47% of patients with proximal ascending sclerosis showed no reactivity towards the alpha-sympatholyticum tolazoline hydrochloride due to severe organic changes while in patients with acroscleroderma only 14% of patients did not respond to tolazoline hydrochloride. The severity of Raynaud's phenomenon did not correlate with the severity of the angiographic findings. In patients with stenoses refractory to tolazoline hydrochloride and in those with occlusions Scl-70 autoantibodies were more frequently positive than in other patients with SSc (44% compared to 23%). CONCLUSION: As in SSc the severity of the organic arterial changes is in close correlation with the extent of the cutaneous sclerosis and with the serological findings the arterial system should gain much more importance in the diagnosis and therapy of SSc.

Aged↗
PubMed2000

From above threshold ionization to statistical electron emission: the laser pulse-duration dependence of C60 photoelectron spectra

The photoelectron spectra of C60 ionized using a 790 nm laser with pulse durations varying from 25 fs to 5 ps have been determined. For 25 fs pulses, in the absence of fragmentation, the ionization mechanism is direct multiphoton ionization with clear observation of above threshold ionization. As the pulse duration is increased, this becomes dominated by a statistical ionization due to equilibration among the electronic degrees of freedom. For pulse durations on the order of a ps coupling to the vibrational degrees of freedom occurs and the well-known phenomenon of delayed (&mgr;s) ionization is observed.

Journal Article↗
PubMed2000

Momentum distributions of ne(n+) ions created by an intense ultrashort laser pulse

Vector momentum distributions of Ne(n+) (n = 1,2,3) ions created by 30 fs, approximately 1 PW/cm(2) laser pulses at 795 nm have been measured using recoil-ion momentum spectroscopy. Distinct maxima along the light polarization axis are observed at 4.0 and 7.5 a.u. for Ne2+ and Ne3+ production, respectively. Hence, mechanisms based on an instantaneous release of two (or more) electrons can be ruled out as a dominant contribution to nonsequential strong-field multiple ionization. The positions of the maxima are in accord with kinematical constraints set by the classical "rescattering model."

Journal Article↗
PubMed2000

Blood cytokine response of low-dose molgramostim (rhGM-CSF)-treated patients.

We examined leukocyte counts and ex vivo cytokine response of whole blood to lipopolysaccharide (LPS) or lipoteichoic acid (LTA) in patients under low-dose molgramostim therapy. Patients were injected subcutaneously daily for ten days with 1 microg/kg (n=9) or 2 microg/kg (n=14) molgramostim. Leukocytosis was observed in all patients, but only the eosinophil fraction was significantly increased in relation to other leukocyte populations. Ex vivo IFN-gamma release was decreased and IL-10 and IL-1ra secretion were increased in response to LPS or LTA. Thus, in non-neutropenic patients, leukocytosis can already be initiated by low doses of molgramostim. The ex vivo cytokine data suggest that these doses prime blood towards a systemic anti-inflammatory response.

Adult↗
PubMed2000

[Bilateral segmental neurofibromatosis simulating epidermal nevus].

Neurofibromatosis is a neuroectodermal systemic disease. A rare variant of this condition is bilateral segmental neurofibromatosis. A 29-year-old man presented with bilateral papillomatous plaques in the lumbar dermatomes. Clinically, the lesions were very similar to an epidermal nevus but histologic examination revealed superficial neurofibromas. Family history, ophthalmologic and neurologic investigations were unremarkable. The unusual morphologic presentation of bilateral segmental neurofibromas in this case points to the wide clinical spectrum of the disease and the significance of histologic examination in systematic nevoid lesions.

Adult↗
PubMed2000

UVA1 irradiation induces deoxyribonuclease dependent apoptosis in cutaneous T-cell lymphoma in vivo.

Cutaneous T-cell lymphoma (CTCL) is a malignancy of mature T-cells, predominantly of the helper phenotype, that primarily invade the skin. Different photo- and chemotherapeutic treatments are known to be beneficial in early-stage CTCL. This observation has initiated prospective investigations into the efficacy of phototherapeutic regimens. The purpose of our study was to investigate the ability of medium-dose UVA1 phototherapy (60 J/cm2) to induce apoptosis (programmed cell death) in skin infiltrating T-cells of CTCL in vivo. We describe the results of three different staining methods for formalin-fixed, paraffin-embedded tissue sections. The in situ end-labeling (ISEL) procedure, nuclear staining using the DNA-binding fluorochrome Hoechst 33342, and immunohistochemistry using polyclonal antibodies against recombinant mouse deoxyribonuclease I (DNase I) demonstrated that UVA1 irradiation was able to induce marked apoptosis in CTCL. Thereby, ISEL and Hoechst staining clearly revealed DNA-condensation and nuclear fragmentation, accompanied by the formation of typical "apoptotic bodies". The accumulation of DNase I immunoreactivity in the cytoplasm of lymphocytes in UVA1 irradiated skin indicated that DNase I or DNase I-related endonucleases may have acted as apoptotic endonuclease(s) which were synthesized after UVA1 irradiation prior to their apoptotic elimination.

Aged↗
PubMed2000

Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis maps to chromosome 3q27 and is associated with mutations in the PCLN-1 gene.

Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC, MIM 248250) is a complex renal tubular disorder characterised by hypomagnesaemia, hypercalciuria, advanced nephrocalcinosis, hyposthenuria and progressive renal failure. The mode of inheritance is autosomal recessive. A primary defect in the reabsorption of magnesium in the medullary thick ascending limb of the loop of Henle (mTAL) has been proposed to be essential in FHHNC pathophysiology. To identify the underlying genetic defect we performed linkage analysis in eight families, including three with consanguineous marriages. We found linkage to microsatellite markers on chromosome 3q27 with a maximum two-point lod score (Zmax) of 5.208 for D3S3530 without evidence for genetic heterogeneity. Haplotype analysis revealed crucial recombination events reducing the critical interval to 6.6cM. Recently, mutations in the gene PCLN-1, mapping to 3q27 and coding for paracellin-1, were identified by Simon et al (1999) as the underlying genetic defect in FHHNC. Paracellin-1 represents a renal tight junction protein predominantly expressed in the TAL. Mutational analysis in our patient cohort revealed eight different mutations in the PCLN-1 gene, within six novel mutations. In seven of 13 mutant alleles we detected a Leu151 substitution without evidence for a founder effect. Leu151 is a residue of the first extracellular loop of paracellin-1, the part of the protein expected to bridge the intercellular space and to be important for paracellular conductance. This study confirms the implication of paracellin-1 defects in FHHNC and points to a predominant role of this protein in the paracellular reabsorption of divalent cations in the TAL.

Amino Acid Substitution↗
PubMed2000

Clearance of ichthyosis linearis circumflexa with balneophototherapy.

We report a 13-year-old boy suffering from severe ichthyosis linearis circumflexa. Evidence of hair shaft abnormalities and impaired immunity could not be found. The patient was treated with salt water baths and artificial UVB radiation (balneophototherapy) 3-5 times weekly. After 40 treatments with balneophototherapy the skin lesions were almost completely cleared and maintenance UVB monotherapy was performed twice weekly for 2 months. After 4 months, however, the disease relapsed. Balneophototherapy presents a potentially effective and well tolerated phototherapeutic option for ichthyosis linearis circumflexa. As only short periods of remission may be expected, intermittent balneophototherapy would be probably necessary to control the disease.

Adolescent↗
PubMed2000

The transepidermal oxygen flux from the environment is in balance with the capillary oxygen supply.

It has been known since the nineteenth century that oxygen is taken up by the human skin. With a newly developed sensor it became possible to examine the influence of the vascular supply on the oxygen flux into the skin, tcJ(O2). tcJ(O2) was measured optically by determining the oxygen partial pressure difference, DeltapO2 across a diffusion test membrane, which itself was brought into close contact to the skin surface. Under these conditions DeltapO2 is proportional to the tcJ(O2). The skin perfusion was varied by the application of a hyperemizing ointment on the abdomen of 12 volunteers and by suprasystolic occlusion at the thigh of 20 volunteers. The tcJ(O2) was measured at a temperature of 33 degrees C of the humid skin. It was compared with the skin perfusion monitored by laser Doppler flow, and the capillary oxygen supply measured by transcutaneous partial pressure of oxygen, tcpO2, at an electrode temperature of 37 degrees C. The transcutaneous O2 flux produced a distinct DeltapO2 of 81.8 +/- 8.2 Torr (abdomen) and 72.8 +/- 12.3 Torr (ankle). In hyperemic skin on the abdomen the O2 flux was reduced (DeltapO2 = 57.7 +/- 10.6 Torr). The tcpO2 increased from 8.7 +/- 10.7 to 35.1 +/- 16.9 Torr. During suprasystolic occlusion, DeltapO2 increased by 6.4 +/- 2.3 Torr, whereas laser Doppler flow and tcpO2 decreased significantly. These results indicate that the total oxygen supply of the epidermis and the upper dermis is guaranteed even if the perfusion varies.

Adult↗
PubMed2000

Deep shave excision of macular melanocytic nevi with the razor blade biopsy technique.

BACKGROUND: Shave excision is an established surgical method for removing benign skin lesions for cosmetic and functional reasons. Usually superficial shave excision is performed with a common scalpel blade for the removal of papular nevi. However, there is little known about deep shave excision of macular melanocytic nevi with the razor blade technique. OBJECTIVE: The present study was undertaken to evaluate the cosmetic outcome of deep shave excision of macular melanocytic nevi with the razor blade technique. Moreover, its potency for sufficient removal of these lesions was investigated. METHODS: Within routine skin cancer screening 45 outpatients with a total of 77 macular melanocytic nevi were prospectively recruited. Deep shave excisions of these lesions were performed with a double-edged razor blade followed by chemical hemostasis. Histologically all specimens were processed and evaluated in a routine manner. After 6 months the physician and patients evaluated the shave sites for cosmetic outcome with a score graded from 1 to 4 (1 = excellent; 2 = good; 3 = moderate; 4 = poor). RESULTS: Histologically 88% (68 of 77) of the melanocytic lesions were described as completely excised and 60% (46 of 77) were diagnosed as atypical melanocytic nevi; 12% (9 of 77) of the nevi were incompletely excised on the depth. On average, the deep margin of the specimens (n = 77) was 0.5 mm (range 0-1.8 mm) and the lateral margin was 2 mm (range 0.3-8.2 mm). After 6 months 56 shave sites could be reassessed. We observed mild hypopigmentation in 52% (29 of 56), hyperpigmentation in 32% (18 of 56), and erythema in 23% (13 of 56). Recurrent nevi occurred in 13% (7 of 56). The evaluation of the cosmetic outcome by the patients (mean score 1.7) achieved better results than the evaluation by the physician (mean score 2.5). The cosmetic results showed no significant (P >.05) differences in various anatomic sites. CONCLUSION: Our data confirm that deep razor blade excision presents a highly useful and inexpensive method for the removal of macular melanocytic nevi that yields adequate specimens for pathologic interpretation. We consider that shave excision with the razor blade technique is potentially much less scarring than full-thickness scalpel excisions of nevi. In particular, this is of great significance for patients with multiple nevi, such as dysplastic nevi syndrome.

Adolescent↗
PubMed2000

In vitro and in vivo determination of the UV protection factor for lightweight cotton and viscose summer fabrics: a preliminary study.

BACKGROUND: One of the most important elements in the prevention of skin cancer is the use of comfortable UV-protective clothing. Owing to their low weight, cotton fabrics, and especially viscose fabrics made from filament yarns, are ideal for summer clothing and in fact enjoy a high degree of acceptance among consumers. Two methods are available for determining the UV protection factor (UPF) of textiles: the in vitro method is based on the spectrophotometric determination of the transmission of UV radiation through these fabrics; the in vivo method is based on the determination of the minimal erythema dose for a test subject with and without textiles. OBJECTIVE: This study was performed to assess the UPF of lightweight cotton and viscose fabrics and whether the use of these two methods to determine the UPF of viscose fabrics and cotton fabrics produces congruent results. METHODS: We tested 7 different viscose fabrics and 7 different cotton fabrics. Three of the viscose fabrics (ENKA SUN) had been specially treated, by depositing pigments in the fibers, to confer UV-protective properties. The determination of the in vitro and in vivo UPF was performed with a spectrophotometer and sun simulator, respectively. RESULTS: The in vivo measurements on the untreated viscose fabrics produced UPF values lower than those obtained from the in vitro measurements. For one of these untreated viscose fabrics, the difference between the in vivo UPF and the in vitro UPF was statistically significant (P <.05). In contrast, the in vivo measurements on the specially treated viscose textiles and on the cotton fabrics resulted in UPF values higher than the in vitro UPF values. For one specially treated viscose fabric and 4 cotton fabrics, this difference was statistically significant (P < .05). CONCLUSION: Our results suggest, however, that-depending on the type of fabric-determination of the UPF by the in vitro method is not in agreement with the in vivo method. In vivo measurements made with lightweight specially treated UV-protective clothing showed in contrast to the untreated viscose fabrics that these garments offer very good protection against UV radiation. These results underscore the importance of developing and refining such UV-protective materials.

Adult↗
PubMed2000

Genetic mapping of the Tsw locus for resistance to the Tospovirus Tomato spotted wilt virus in Capsicum spp. and its relationship to the Sw-5 gene for resistance to the same pathogen in tomato.

The Tsw gene conferring dominant resistance to the Tospovirus Tomato spotted wilt virus (TSWV) in Capsicum spp. has been tagged with a random amplified polymorphic DNA marker and mapped to the distal portion of chromosome 10. No mapped homologues of Sw-5, a phenotypically similar dominant TSWV resistance gene in tomato, map to this region in C. annuum, although a number of Sw-5 homologues are found at corresponding positions in pepper and tomato. The relationship between Tsw and Sw-5 was also examined through genetic studies of TSWV. The capacity of TSWV-A to overcome the Tsw gene in pepper and the Sw-5 gene in tomato maps to different TSWV genome segments. Therefore, despite phenotypic and genetic similarities of resistance in tomato and pepper, we infer that distinct viral gene products control the outcome of infection in plants carrying Sw-5 and Tsw, and that these loci do not appear to share a recent common evolutionary ancestor.

Capsicum↗
PubMed2000

Change in ultraviolet (UV) transmission following the application of vaseline to non-irradiated and UVB-exposed split skin.

BACKGROUND: Topical preparations such as emollients used in combination with phototherapy can interfere with such treatment. OBJECTIVES: This study was performed to investigate the impact of vaseline on the ultraviolet (UV) transmission of non-irradiated split skin and on split skin previously exposed to UVB radiation. METHODS: Split-skin specimens were obtained from 20 patients. In each case, one sample was taken from an area of non-irradiated skin, while the second was taken from an area that had been previously exposed to UVB. The transmission was spectrophotometrically measured with split skin placed in specially designed quartz glass cuvettes before and after the application of two different amounts of vaseline (2.5 and 17.5 mg cm-2). RESULTS: Application of vaseline to skin previously exposed to UVB caused significant (P < 0.0001) changes in UV transmission in certain wavelength ranges. In the UVA range, a greater increase in transmission was achieved with 2.5 mg cm-2 vaseline, whereas in the UVB range, a greater increase was achieved with 17.5 mg cm-2 vaseline. The thicker the layer of vaseline applied, the lower was the difference in transmission between non-irradiated split skin and UVB-exposed split skin. CONCLUSIONS: Application of the correct amount of vaseline can enhance transmission in either the UVA or UVB range, and would enable dose reduction during a course of phototherapy.

Adult↗
PubMed2000

Disruption of the 11-cis-retinol dehydrogenase gene leads to accumulation of cis-retinols and cis-retinyl esters.

To elucidate the possible role of 11-cis-retinol dehydrogenase in the visual cycle and/or 9-cis-retinoic acid biosynthesis, we generated mice carrying a targeted disruption of the 11-cis-retinol dehydrogenase gene. Homozygous 11-cis-retinol dehydrogenase mutants developed normally, including their retinas. There was no appreciable loss of photoreceptors. Recently, mutations in the 11-cis-retinol dehydrogenase gene in humans have been associated with fundus albipunctatus. In 11-cis-retinol dehydrogenase knockout mice, the appearance of the fundus was normal and punctata typical of this human hereditary ocular disease were not present. A second typical symptom associated with this disease is delayed dark adaptation. Homozygous 11-cis-retinol dehydrogenase mutants showed normal rod and cone responses. 11-cis-Retinol dehydrogenase knockout mice were capable of dark adaptation. At bleaching levels under which patients suffering from fundus albipunctatus could be detected unequivocally, 11-cis-retinol dehydrogenase knockout animals displayed normal dark adaptation kinetics. However, at high bleaching levels, delayed dark adaptation in 11-cis-retinol dehydrogenase knockout mice was noticed. Reduced 11-cis-retinol oxidation capacity resulted in 11-cis-retinol/13-cis-retinol and 11-cis-retinyl/13-cis-retinyl ester accumulation. Compared with wild-type mice, a large increase in the 11-cis-retinyl ester concentration was noticed in 11-cis-retinol dehydrogenase knockout mice. In the murine retinal pigment epithelium, there has to be an additional mechanism for the biosynthesis of 11-cis-retinal which partially compensates for the loss of the 11-cis-retinol dehydrogenase activity. 11-cis-Retinyl ester formation is an important part of this adaptation process. Functional consequences of the loss of 11-cis-retinol dehydrogenase activity illustrate important differences in the compensation mechanisms between mice and humans. We furthermore demonstrate that upon 11-cis-retinol accumulation, the 13-cis-retinol concentration also increases. This retinoid is inapplicable to the visual processes, and we therefore speculate that it could be an important catabolic metabolite and its biosynthesis could be part of a process involved in regulating 11-cis-retinol concentrations within the retinal pigment epithelium of 11-cis-retinol dehydrogenase knockout mice.

Alcohol Oxidoreductases↗