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Biomedical subjects

K Hoffmann

Publications and source records attributed to K Hoffmann.

At least 235 records · Page 13Linked to original sources
PubMed1993

Influence of short photoperiods on reproductive organs and estrous cycles of normal and pinealectomized female Djungarian hamsters, Phodopus sungorus.

This study was designed to analyze morphological changes in the reproductive organs and endocrine changes in the serum and pituitaries of female Djungarian hamsters during regression, the period of involution and early spontaneous recrudescence in response to short photoperiods. In addition, the involvement of the pineal gland on the inhibitory response to short photoperiods was investigated. In the first study, 63 adult female hamsters were divided into five groups, which were either pinealectomized at the time of transfer or 11 wk after transfer into short photoperiods, or exposed to different light regimens. The estrous cycles of these hamsters were recorded by vaginal smears for a period of 34 wk. In a second study, 156 adult female hamsters were divided into 14 groups and maintained under the influence of long or short photoperiods for 0-33 wk. The animals were killed by decapitation at 3-wk intervals and analyzed for changes in body weight and morphology of the vagina, ovary, and uterus. A loss of cyclic activity and complete involution of uterus and vagina were observed between Week 9 and Week 27 after transfer into short photoperiods. During this time period, no corpora lutea were observed in the ovaries. Under the influence of short photoperiods, the numbers of medium and antral follicles declined continuously until Week 15, and afterwards gradually recovered to maximal numbers in Week 27. This biphasic response to short photoperiods was not observed in the number of small follicles. These morphological changes were accompanied by changes in serum and pituitary FSH concentrations. Pinealectomy prevented the loss of estrous cyclicity after transfer into short photoperiods.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A wound healing model with sonographic monitoring.

The methods used hitherto for quantification of skin repair processes only allow an examiner a two-dimensional assessment of superficial wound healing. With the recent advent of high frequency B-scan ultrasonography in dermatology it has become possible to follow the course of healing and evaluate the healing processes in deeper layers of the skin. In this investigation 80 patients received cryosurgery for treatment of basal cell carcinomas on the face or neck region. As the size of cryosurgical defects can be precisely controlled they are potentially useful as standardized wound healing models. The course of wound healing after cryosurgery using a digital ultrasound scanner (DUB 20, Taberna pro medicum, Lüneburg, Germany) was monitored. The usable depth of penetration of the echo signal is approximately 7 mm. The lateral resolution is approximately 200 microns, the axial resolution approximately 80 microns. The cryolesion and the repair processes were examined ultrasonographically and clinically over a period of at least 3 weeks or until the wound had completely healed. The depth of invasion and lateral extent of the basal cell carcinoma as well as the size of the induced cryolesion can be determined by ultrasound. The exudative phase after cryosurgery, with developing oedema and necrosis, can be quantified on the basis of the reduced reflectivity in the corium. The repair processes taking place in the region of necrosis can be visualized in the ultrasound scan. The ultrasonically monitored wound healing model which we have demonstrated is particularly suitable for investigating the efficacy of drugs which promote healing.

Aged↗
PubMed1993

Antipyrine elimination in patients with alcoholic and non-alcoholic cirrhosis.

The metabolism of antipyrine to each of its three major metabolites 4-hydroxy-, 3-methylhydroxy- and norantipyrine has previously been demonstrated to be differentially affected in alcoholic cirrhosis. This study compared the metabolism of antipyrine to its metabolites in 30 patients with alcoholic cirrhosis to 15 patients with non-alcoholic cirrhosis and 20 healthy controls. Both groups of cirrhotic patients were comparable with respect to their disease stage, as assessed by the Child-Pugh classification. Compared to controls, patients with alcoholic and non-alcoholic cirrhosis showed a comparable significant reduction in antipyrine clearance and increase in antipyrine half-life. The reduction in antipyrine clearance was due to a reduction in the formation rate of all three antipyrine metabolites in both alcoholic and non-alcoholic cirrhotics. In both groups, the formation rate of norantipyrine was reduced to a greater extent than of 3-methylhydroxy- and 4-hydroxyantipyrine. No significant differences in the parameters of antipyrine elimination, however, were observed between patients with alcoholic and non-alcoholic cirrhosis. Parameters of antipyrine elimination correlated significantly to the Child-Pugh score and single laboratory parameters, however, the correlation coefficients were generally low (< 0.56). The present results suggest that the P450 enzymes involved in antipyrine metabolism are differentially affected in cirrhosis, but there appear to be no differences in the activity of the enzymes between alcoholic and non-alcoholic cirrhosis. Antipyrine metabolism, therefore, depends on the severity rather than the etiology of liver disease and may serve as a measure of hepatic function irrespective of the cause of liver disease.

Adult↗
PubMed1993

[Imre modified bilobed flap rotation graft for plastic surgery management of skin tumors in the area of the nose and eyes].

The modification and development of the rotation-flap graft described by Imre in 1924 gave rise to the bilobed flap rotation graft, which is now a standard operative method of defect coverage and corrective plastic surgery, especially for the facial region. The advantages of this operative technique are presented with reference to case reports. They result from its ability to neutralize the tractive and expansion forces that arise within the tissue and to guarantee adequate blood supply to and innervation of the rotation flap by shifting the axis of rotation to a site far distant from the operating area.

Aged↗
PubMed1993

[Cutaneous condylomata acuminata of an unusual site and extent. Successful CO2 laser therapy].

We report on a 33-year-old patient with unusually extensive and predominantly cutaneous condylomata acuminata spreading from the penis over the mons pubis to the entire lower abdominal wall but almost completely sparing the genital mucous membranes. Single lesions were found on the left arm and on the buttocks. Southern blot hybridization detected HPV-6a DNA sequences within the fibroepithelial tumours. Carbon dioxide laser treatment resulted is cosmetically acceptable healing without recurrence.

Abdominal Neoplasms↗
PubMed1992

Two new cyclophilins from Fusarium sambucinum and Aspergillus niger: resistance of cyclophilin/cyclosporin A complexes against proteolysis.

Two new peptidyl-prolyl-cis/trans-isomerases were purified to homogeneity from Fusarium sambucinum and Aspergillus niger. They belong to the class of cyclosporin A binding proteins (cyclophilins) and have molecular masses of about 18 kDa. As has been shown for other cyclophilins, the isomerase activity of the enzymes is inhibited by cyclosporin A in the nanomolar range. Furthermore binding of cyclosporin A prevents proteolytic digestion of the cyclophilin/cyclosporin complexes by the endoproteases GluC, LysC and alpha-chymotrypsin, in contrast to the free cyclophilins, which are readily cleaved by these proteases. We could also observe this protection for cyclophilins from sheep thymus and from the cyclosporin producing fungus Tolypocladium inflatum.

Amino Acid Isomerases↗
PubMed1992

Nuclear factor I (NF I) binds to an NF I-type site but not to the CCAAT site in the human alpha-globin gene promoter.

Methylation interference and missing contact analyses demonstrate that nuclear factor I (NF I) recognizes an NF I-like site (5'-GGG(N)6GCCAG-3') within the alpha-globin promoter rather than the adjacent CCAAT box. Consistent with this, mutations within the CCAAT box do not alter significantly the affinity and specificity of the interaction whereas elimination of the 5'-GGG-3' half-site of the recognition sequence reduces the DNA binding strength of NF I by 2 orders of magnitude down to the range of unspecific interaction. On the other hand, the mutated alpha-globin promoter sequence that is no longer bound by NF I, although it retains an intact CCAAT box, interacts specifically with a protein component from nuclear extracts of HeLa cells. From these results we conclude that NF I is not the factor that interacts with the CCAAT box and that the second half of the canonical 5'-TGG(N)6GCCAA-3' NF I binding site cannot be regarded as identical with the CCAAT promoter element, as suggested previously.

Autoradiography↗
PubMed1992

Human-immunodeficiency-virus-type-1-encoded Vpu protein is phosphorylated by casein kinase II.

Vpu as a human-immunodeficiency-virus-type-1-encoded 81-amino-acid integral-membrane protein was expressed in Escherichia coli using the inducible ptrc promoter of an ATG fusion vector. Recombinant Vpu is associated with membranes of E. coli and could be partially solubilized by detergents. Recombinant Vpu was phosphorylated in vitro with purified porcine casein kinase II (CKII) as well as with a CKII-related protein kinase found in cytoplasmic extracts of human and hamster cells. Recombinant Vpu associated with E. coli membranes has turned out to be the best substrate for in vitro phosphorylation with CKII. This reaction can be inhibited by heparin and the ATP analogue 5,6-dichloro-1-(beta-D-ribofuranosyl)benzimidazole (DRB), both known to be potent inhibitors of CKII. Radiolabelled gamma ATP and gamma GTP were used as phosphate donors in vitro phosphorylation of recombinant Vpu. In vivo phosphorylation of Vpu in HIV-1-infected H9 cells was also inhibited by DRB. We concluded therefrom that the Vpu protein is phosphorylated by the ubiquitous CKII in HIV-1-infected human host cells. Two seryl residues in the sequence of Vpu (position 52 and 56) correspond to the consensus S/TXXD/E for CKII. These potential phosphorylation sites are located within a well-conserved dodecapeptide of Vpu (residues 47-58), which is found in different HIV-1 strains as well as in a Vpu-like protein of SIVCPZ. Monoclonal and polyclonal antibodies directed against two different epitopes of Vpu were used for immunoprecipitation of Vpu from HIV-1-infected cells and for detection of Vpu in Western blot analyses. Vpu from HIV-1-infected cells as well as recombinant Vpu expressed in E. coli were determined by SDS/PAGE using 6 M urea to be 9 kDa, which corresponds to the calculated molecular mass of Vpu.

Adenosine Triphosphate↗
PubMed1992

FK-506 binding protein from Tolypocladium inflatum: resistance of FKBP/FK-506 complex against proteolysis.

A 12-kDa peptidyl-prolyl-cis/trans-isomerase was purified 225-fold to homogeneity from the cyclosporin producing fungus Tolypocladium inflatum. The enzyme is highly sensitive to the immunosuppressant FK-506 but not to cyclosporin and thus belongs to the class of FK-506 binding proteins (FKBP). Interestingly the FKBP/FK-506 complex is resistant against proteolytic digestion by the endoproteases GluC and LysC, in contrast to the free FKBP, which is readily cleaved by these proteases. This protection may play a role in the effects of FK-506 in the living cell.

Amino Acid Isomerases↗
PubMed1992

Physiopathology of the knee joint after distal iliotibial band transfer.

In an experimental study of 14 cadaver knee joints, the pressure load on the joint surface after distal iliotibial band transfer was measured using Fuji Prescale foils. With an intact anterior cruciate ligament, increases of up to 153% for the average pressure load and of 225% for the total pressure in the lateral compartment were found in relation to the fixation point chosen. At point P3--slightly dorsal to the insertion of the lateral collateral ligament--the area loaded with maximum pressure increased to six-fold. Fixation at the transition of the lateral femoral condyle to the femoral shaft at the start of the linea aspera was associated with the least pressure increases in both the lateral and the medial compartments. Under all experimental conditions, lateral extra-articular stabilization with fixation at the insertion of the fibular collateral ligament was shown to be associated with significantly higher load increases. While a shift of pressure load to the dorsal third was seen in the lateral compartment, the mid-third remained the focus of the pressure load in the medial compartment. After transection of the anterior cruciate ligament and iliotibial band transfer at the "over-the-top" point, a significant shift of pressure towards the medial compartment was seen, while the lateral pressure load decreased. Medially, the area loaded with peak pressure remained constant, while the corresponding area in the lateral joint space showed a highly significant decrease to nearly one-third of normal. After additional bilateral meniscectomy this tendency was even more pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament↗
PubMed1992

Pattern of pineal melatonin concentrations during prolonged exposure to short photoperiods in photosensitive and photoinsensitive Djungarian hamsters.

In the Djungarian hamster (Phodopus sungorus) there is strong evidence that the nightly decompression or lengthening, respectively, of the pineal melatonin pattern is involved in conveying the inhibitory influence of short photoperiods. Some hamsters, however, are insensitive to photoinhibitory influences; other late-responding hamsters show a delayed reaction of several months. The daily pattern of pineal melatonin proves that the mechanisms determining long- or short-day patterns become effective in the morning and evening hours when melatonin concentrations of photoinhibited hamsters are clearly elevated, while those of long-day hamsters are reduced to negligible low values. At two decisive time points in the morning and evening, male and female early-responding photosensitive hamsters were killed after 5, 10, 15, and 20 weeks in short photoperiods, nonresponding hamsters after 10 and 20 weeks, and late-responding after 20 weeks. In all early-responding hamsters changes in gonadal stage, body weight, and pelage color corresponded to the decompression of the nightly melatonin pattern. During prolonged exposure to short photoperiods a decrease of mean melatonin concentrations in the morning and an increase of evening concentrations was observed in both sexes. The lengthening of nightly elevated melatonin concentrations was missing in photoinsensitive hamsters. In late-responding hamsters this decompression seems to be delayed, as melatonin concentrations of female late responders indicate. In conclusion, the lengthening of the melatonin pattern seems to predict a photoperiodic reaction of the effector system. The lengthened pattern of photosensitive hamsters may not be unchangeable, as it may be subjected to modifications during prolonged exposure to short photoperiods.

Animals↗
PubMed1992

Malignant melanoma in 20-MHz B scan sonography.

In order to assess the value of 20-MHz sonography in the pre-operative diagnosis of malignant melanomas, 54 melanomas were examined. The pre-operative ultrasound scans were compared with corresponding histological sections from the excised tumours. A computer-aided measurement of the tumour thickness (sonometry) and the internal echo density (densitometry) was performed in the ultrasound scans. The melanomas appeared as largely echolucent zones. There was a significant correlation between the tumour thickness measured in the ultrasound scan and those measured in the histological sections (r = 0.938, p less than 0.001). As a rule the tumour thickness determined by sonometry were greater than the histometrically determined values. Subtumoral inflammatory infiltrate and other hypo-echoic structures in the region of the tumour are possible causes of the discrepancies. Some of those hypo-echoic structures can be identified and disregarded in B scan measurement. Even if a definite differential diagnosis is not possible on the basis of the ultrasound scan alone, 20-MHz sonography provides additional information which can be of use in surgical planning.

Adolescent↗
PubMed1992

A seventeen kilodaltons peptidyl-prolyl cis-trans isomerase of the cyclosporin-producer Tolypocladium inflatum is sensitive to cyclosporin A.

A peptidyl-prolyl cis-trans isomerase (PPIase) was purified to homogeneity about 24-fold from the cyclosporin-producing fungus Tolypocladium inflatum. The molecular mass of the enzyme was in the range of 17 kdaltons. Remarkably, the enzyme could be inhibited by cyclosporin A in the nanomolar range as has been shown for numerous other cyclophilins from eukaryotic organisms. This indicates, that Tolypocladium inflatum must possess a self protection system in order to survive in the presence of cyclosporin.

Amino Acid Isomerases↗
PubMed1992

[Ultrasound diagnosis of skin tumors].

Twenty-one patients with skin tumors were examined before and after operation using special high-frequency ultrasound B-scanners. The different histological types were related to sonographic phenotypes, and the extent of tumors in the ultrasound image was comparable with that seen on the histometric image. The extent and invasion depth of skin tumors were assessed correctly by ultrasound.

Basal Cell Carcinoma↗
PubMed1991

Number of helper T cells and phytohemagglutinin stimulation correlate in cancer patients.

Mononuclear cells from 12 normal controls (co), 10 advanced untreated (c1), and 6 advanced treated cancer patients (c2) have been isolated. The numbers of mononuclear cells bearing Leu1, Leu2, Leu3, Leu2/HLA-DR and LeuM3 were measured with a fluorescence-activated cell sorter. Only the quantity of helper T cells (Leu3) was decreased in cancer patients (co: 0.89, cl: 0.32, c2: 0.44 x 10(9)/l). Expression of all other markers, including activated suppressor T cells (Leu2/HLA-DR), did not differ significantly from the control. The proliferation of the lymphocytes was determined in a phytohemagglutinin-culture assay. The cancer groups showed a significantly decreased response (co: 95.8 x 10(9), cl: 28.7 x 10(9), c2: 25.7 x 10(9) cpm). These values correlated with the number of helper T cells but not with the suppressor T cells. Monocytes of cancer patients absorbed significantly more immunoglobulins than the monocytes of controls. The addition of indomethacin or isoprinosine to phytohemagglutinin-culture assay increased the proliferation of lymphocytes from both the cancer patients and normal controls.

Adult↗
PubMed1991

20-MHz B-mode ultrasound in monitoring the course of localized scleroderma (morphea).

Ultrasonographic methods have recently provided us with the means for objective and non-invasive monitoring of the dynamics of chronic skin diseases. We examined 34 patients with localized scleroderma (morphea) using a 20-MHz B-mode ultrasound scanner (DUB 20, Taberna pro Medicum, Lüneburg). In patients with plaque-type and linear band-type localized scleroderma intraindividual comparison of sclerotic skin with corresponding areas of healthy skin showed thickening of the corium. The increase in corium thickness was between 2% and 251%. The extent of the difference in corium thickness between sclerotic and healthy skin depended on the location-originally thin skin showed a greater degree of sclerosis. We also frequently found enhanced reflexes in the lower corium and hyperechoic, widened bands of connective tissue traversing the subcutaneous fatty tissue from the corium-subcutis border in the direction of the muscle fascia. 20 patients were examined several times in the course of one year. In nine patients we found ultrasonographic evidence of regression (decrease in thickness 26%) and in nine the ultrasound examination showed progression (increase in thickness 28%). 20-MHz B-mode ultrasound imaging is a suitable non-invasive method for monitoring the course and treatment of localized scleroderma. Its routine use is strongly recommended.

Adolescent↗