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Biomedical subjects

C Schulz

Publications and source records attributed to C Schulz.

At least 19 recordsLinked to original sources
PubMed2001

[Correlation between histopathology and epiluminescent microscopy in nonmelanocytic skin lesions].

Epiluminescence microscopy techniques make surface and subsurface structures accessible to visual examination in vivo. The visualization of a multitude of special morphological features, such as blood vessels, adnexa and deposits of pigments in normal and pathologically changed skin allows a reproducible and topographical stratification. There is a chance of identifying the architecture of the stratum corneum, the epidermis and the papillary bodies. Changes in the amount of melanin can be individually assessed in the stratum corneum and the deeper layers extending into the upper dermis. It is possible to differentiate the orientation, size and color of the blood vessels of the cutaneous vascular plexus, involving the capillaries of the stratum papillare and the subpapillary plexus.

Equipment Design↗
PubMed2001

The effects of the selective serotonin reuptake-inhibitor fluvoxamine on body weight in Zucker rats are mediated by corticotropin-releasing hormone.

Brain serotonin plays a crucial role in the regulation of food intake and body weight homeostasis. Previous data suggest an interaction with corticotropin-releasing hormone (CRH). To further examine the interaction between these neurotransmitters, the selective serotonin reuptake-inhibitor (SSRI) fluvoxamine was given intraperitoneally in fa/fa Zucker rats with and without the CRH-receptor-antagonist alpha-helical CRH administered intracerebroventricularly (i.c.v.). The saline treated animals gained weight. Fluvoxamine led to a significant weight loss while not affecting food intake. Furthermore, insulin levels in this animal model were reduced following fluvoxamine administration. These effects were antagonized by alpha-helical CRH and are thus most likely mediated via CRH or CRH-like peptides.

Animals↗
PubMed2001

The surgical treatment of Kienböck's disease by radius and ulna metaphyseal core decompression.

We present a new surgical procedure, metaphyseal core decompression, to treat Kienböck's disease. Twenty-two patients were treated between 1976 and 1988 and were retrospectively reviewed. Sixteen were male and 6 female with an average age of 36 years (range, 18-64 years). The surgical technique involved curettage of the distal radius and ulna metaphyseal bone through small cortical windows. The average follow-up period was 10 years (range, 6-16 years). No postoperative complications were noted and no patient underwent additional surgical procedure. Sixteen patients were pain-free; 4 noted occasional pain. Twenty returned to their prior occupation. One patient had moderate pain and altered his occupation. Another had increasing pain and had x-ray evidence of advanced intercarpal arthritis. The average arc of wrist extension and flexion was 77% of the opposite wrist and the average grip strength was 75%. Long-term follow-up monitoring indicates that the metaphyseal core decompression produces results at least as good as other surgical procedures without any postoperative complications.

Adult↗
PubMed2001

[Heparin-induced type II thrombocytopenia as the etiology of severe recurrent pulmonary embolism].

Heparin-induced thrombocytopenia (HIT) is a rare complication of anticoagulative heparin therapy. The more severe HIT type II is defined by peripheral thrombocytopenia combined with thrombotic and thromboembolic events. We report the case of a 24 year old male patient who was admitted to our ICU with thromboembolic obstruction of the right central pulmonary artery, and deep venous thrombosis (DVT) of the right superficial femoral vein. Systemic thrombolytic therapy with urokinase for seven days resulted in nearly complete resolution of the thromboembolic material in the pulmonary arteries. Antithrombotic therapy with intravenous heparin and overlapping oral phenoprocoumon was continued on the regular ward. Six days later, the patient had to be readmitted to the ICU with evidence of hemodynamic compromise due to massive bilateral pulmonary thromboembolism that could be confirmed by CT scan--DVT had extended to the right iliacal vein. Additionally, peripheral thrombocyte counts had markedly declined from 112.000 to 35.000/microliter within 3 days, indicating the presence of a Hit type II. This was verified by positive ELISA testing for antibodies against platelet factor 4 (PF4)-heparin-complex. A filter device was temporarily implanted into the inferior vena cava. The patients condition stabilized upon reinitiated systemic thrombolysis and replacement of heparin therapy against recombinant hirudin. Pulmonary artery pressures normalized. Peripheral thrombocytopenia diminished within three days. HIT type II is a severe complication of anticoagulative therapy with heparin. Here we report a case, and discuss diagnostic procedures as well as differential diagnosis to HIT type I.

Adult↗
PubMed2001

Plasma free amino acid concentrations in healthy Guatemalan adults and in patients with classic dengue.

BACKGROUND: Plasma free amino acid patterns in health and disease have been reported. However, amino acid concentrations in adult populations in developing countries and in patients with dengue, as a model for an acute infectious viral disease endemic to the tropics, have not been reported. OBJECTIVE: The purpose of this study was to determine the amino acid profile in both healthy Guatemalan adults from different socioeconomic backgrounds and at 3 time points during the course of classic dengue. DESIGN: The study was carried out in Guatemala and included measurement of plasma free amino acids in 22 healthy control subjects (14 low income, 8 middle class) and 17 febrile patients. Measurements of amino acids were repeated within a 48-h interval in 20 of the healthy Guatemalans. In 9 patients with dengue, amino acids were assayed 3 times: on admission to a local hospital in the coastal plain of Guatemala, on hospital discharge, and 7 d after hospital discharge. RESULTS: Branched-chain amino acid concentrations in healthy adults and dengue patients in Guatemala were lower than normal values reported in the literature for healthy Swedish adults. With the exception of increased phenylalanine concentrations and an increased ratio of phenylalanine to tyrosine, all amino acids as well as the Fischer molar ratio were decreased in the acute phase of dengue. CONCLUSIONS: Healthy Guatemalans have different amino acid patterns than do Swedish subjects independent of socioeconomic status. The systemic viral disease dengue is associated with changes in the plasma free amino acid pattern, reflecting infection-related alterations in amino acid metabolism.

Adult↗
PubMed2001

Effects of corticotropin-releasing hormone on locus coeruleus neurons in vivo: a microdialysis study using a novel bilateral approach.

OBJECTIVE: Stress-induced release of noradrenaline (NA) from locus coeruleus (LC) neurons is mainly regulated by corticotropin-releasing hormone (CRH). Tyrosine is a precursor of NA and plays an intriguing role in the regulation of NA release. DESIGN: We studied the effects of injecting CRH into the LC using a novel bilateral approach which relies on the mainly ipsilateral projections of LC neurons allowing stimulation of one hemisphere while using the other as control. To analyze the modification of the CRH effect, tyrosine was given intraperitoneally. A combination of CRH and its antagonist d-Phe was administered for validation of the specificity of CRH effects. METHODS: Wistar rats were used in all experiments. Injections were made through fused silica capillaries implanted into both LCs and microdialysis samples were collected bilaterally from the prefrontal cortex (PFM) every 20 min for 1 h before and 3 h after injections. The effects of LC stimulation were investigated by determining 3-methoxy-4-hydroxyphenylglycol (MHPG) in the dialysates. RESULTS: Following CRH injection into one LC and contralateral infusion of artificial cerebrospinal fluid (aCSF), MHPG levels, which are indicative of NA release, increased only in the ipsilateral PFM. These effects were blocked by d-Phe. Simultaneous administration of tyrosine i.p. led to a significant prolongation of MHPG release. CONCLUSIONS: These data provide the first physiological evidence of unilateral LC projections with the bilateral stimulation design proving to be a very valuable tool for the study of LC firing rate, to decrease number of animals and time expenditure. Prolongation of MHPG release after tyrosine supplementation is most likely due to increased NA synthesis.

Animals↗
PubMed2000

Endovascular irradiation from beta-particle-emitting gold stents results in increased neointima formation in a porcine restenosis model.

BACKGROUND: Recent studies have shown that ionizing radiation reduces neointima formation after balloon angioplasty and stent implantation in experimental models of restenosis and first clinical trials. The objective of this study was to determine the dose distribution of a new beta-particle-emitting radioactive gold stent and to evaluate the dose-dependent vascular response in the coronary overstretch pig model. METHODS AND RESULTS: Sixteen Göttinger minipigs underwent placement of 11 nonradioactive and 36 beta-particle-emitting stents with activity levels of 10.4+/-0.6, 14.9+/-2.4, 22.8+/-1.3, 35.8+/-2. 8, and 55.4+/-5.3 microCi of (198)Au. Three months after implantation, the percent area stenosis, neointimal thickness, neointimal area, and vessel injury were analyzed by quantitative histomorphometry. The lifetime radiation doses at a depth of 1 mm were 3.3+/-0.2, 4.7+/-0.5, 7.2+/-0.4, 11.4+/-0.9, and 17.6+/-1.7 Gy for the different activity groups. No dose-response relationship was observed in the radioactive stents with respect to percent area stenosis (P=0.297), mean neointimal thickness (P=0.82), or mean neointimal area (P=0.65). Significantly lower neointima formation and less luminal narrowing was seen in the control group than in the beta-particle-emitting stents (P<0.001). Multilinear regression analysis revealed that only radioactivity made a significant independent contribution to the degree of percent area stenosis (P<0. 001). CONCLUSIONS: Neointima formation in pigs is markedly increased by beta-particle-emitting stents with (198)Au as the radioisotope. This study provides evidence that dosages of 3 to 18 Gy of low-dose-rate beta-particle irradiation via endovascular stents cause pronounced luminal narrowing in the animal model at 3 months.

Animals↗
PubMed2000

RANTES in the postoperative course after liver transplantation.

RANTES (regulated upon activation, normal T-cell expressed and secreted), an inflammatory cytokine, promotes accumulation and activation of leukocytes. In 67 liver transplantations, systemic concentrations of RANTES were correlated to graft survival and incidence of rejection. RANTES levels either increased to highly elevated levels at day 14 (84 +/- 64 ng/ml; group 1; n = 43) or remained within the limit of healthy controls (19 +/- 11 ng/ml at day 14; group 2; n = 24). The 100-day graft function rate was 0.91 in group 1 and 0.63 in group 2 (P = 0.002). The risk ratio for rejection during the first 100 days was increased 2.2-fold in group 2 compared to group 1 (P = 0.02). High postoperative release of RANTES after liver transplantation, a beneficial factor, may reflect a general systemic immunological activation. It can be concluded that high early systemic RANTES levels may play a role in immunological recognition leading to a tolerance of the liver graft.

Adolescent↗
PubMed2000

Tay's syndrome: MRI.

Tay's syndrome is a trichothiodystrophy associated with congenital ichthyosis. We report the findings on MRI and spectroscopy in a young girl with sparse, short, ruffled hair, dry skin and delayed milestones. T2-weighted images showed prominent diffuse confluent increase in signal symmetrically in all the supratentorial white matter. These findings are similar to those in a previously described case, and consistent with dysmyelination. Spectroscopy showed increased myoinositol and decreased choline.

Brain↗
PubMed2000

Coronary stent symmetry and vascular injury determine experimental restenosis.

OBJECTIVE: To assess the impact of stent symmetry on restenosis using the coronary overstretch sheep model. METHODS: Neointimal thickness, injury index, and percentage diameter and area stenosis were calculated by digital morphometry. The standard deviation of the angular burden was used to assess stent symmetry for each section. MATERIALS: 15 healthy Merino sheep (63-75 kg) underwent implantation of 30 slotted tube stents (7 mm). Restenosis was induced by calculated overstretch of the coronary artery. Twenty eight days after implantation, stents were excised and underwent histological examination using quantitative digital morphometry. RESULTS: The severity of vessel injury was positively correlated with neointimal thickness and with percentage diameter and area stenosis (p < 0.001). Mean neointimal thickness and mean vascular injury per cross section were strongly related to the standard deviation of angular burden, with correlation coefficients of 0.6 and 0.8, respectively (p < 0.001). CONCLUSIONS: The well known relation between vascular injury and restenosis was confirmed, and a new relation was discovered between stent asymmetry and restenosis. If these results apply to human coronary arteries, restenosis may also be dependent on the degree of asymmetric stent expansion. These results should influence the development of new stent designs to reduce asymmetric stent expansion, leading to a more homogeneous strain distribution in stented coronary segments.

Angioplasty, Balloon, Coronary↗
PubMed2000

Lithium-induced EEG changes in patients with affective disorders.

In 12 patients with affective disorders (ICD-10: F31, F32, F33), EEGs were recorded before and after 4.4 months of lithium treatment. Effects of lithium on the EEG were analyzed by power spectral analysis controlled for vigilance. We found (1) an increase in relative power in both delta and theta band which was related to the lithium plasma level, (2) a decrease in relative alpha power especially at occipital leads and (3) a reduction of the dominant alpha frequency. The changes in relative power were more pronounced in the right hemisphere, which is in contrast to the hypothesis of a site-specific localization of lithium effects only in left anterior regions.

Aged↗
PubMed2000

Heterodimeric versus homodimeric structure of the primary electron donor in Rhodobacter sphaeroides reaction centers genetically modified at position M202.

Using light-induced Fourier-transform infrared (FTIR) difference spectroscopy of the photo-oxidation of the primary donor (P) in chromatophores from Rhodobacter sphaeroides, we examined a series of site-directed mutants with His M202 changed to Gly, Ser, Cys, Asn or Glu in order to assess the ability of these side chains to ligate the Mg atom of one of the two bacteriochlorophylls (BChl) constituting P. In the P+QA-/PQA FTIR difference spectra of the mutants HG(M202), HS(M202), HC(M202) and HN(M202), the presence of a specific electronic transition at approximately 2650-2750 cm-1 as well as of associated vibrational (phase-phonon) bands at approximately 1560, 1480 and 1290 cm-1 demonstrate that these mutants contain a BChl/BChl homodimer like that in native reaction centers with the charge on P+ shared between the two coupled BChl. In contrast, the absence of all of these bands in HE(M202) shows that this mutant contains a BChl/bacteriopheophytin heterodimer with the charge localized on the single BChl, as previously determined for the mutant HL(M202). Furthermore, the spectra of the heterodimers HE(M202) and HL(M202) are very similar in the 4000-1200 cm-1 IR range. Perturbations of the 10a-ester and 9-keto carbonyl modes for both the P and P+ states are observed in the homodimer mutants reflecting slight variations in the conformation and/or in position of P. These perturbations are likely to be due to a repositioning of the dimer in the new protein cavity generated by the mutation.

Dimerization↗
PubMed2000

Expression of a retinoid-inducible tumor suppressor, Tazarotene-inducible gene-3, is decreased in psoriasis and skin cancer.

Tazarotene-induced gene-3 (TIG-3), isolated from human keratinocytes treated with the retinoic acid receptor-selective retinoid Tazarotene, is homologous to H-rev, a class II tumor suppressor. TIG-3 gene localized to chromosome 11q23, a site of loss of heterozygosity in several malignancies. Retinoids influence epidermal differentiation and are used to treat and prevent skin cancer. Therefore, we studied TIG-3 mRNA expression in psoriasis and in basal and SCCs by in situ hybridization and a quantitative QT-RT-PCR assay. Psoriasis lesions had significantly lower staining (median, 3) than paired normal control skin (median, 4; P = 0.012). TIG-3 mRNA was significantly higher in normal control skin (P = 0.001), in paired adjacent skin (median, 3; P = 0.007), and in overlying epidermis (median, 3.0; P = 0.0001) than in 21 SCC specimens as a group (median, 1.5).

Aged↗
PubMed1999

[Evaluation of preoperative functional status in patients with lung cancer].

In view of the dismal prognosis of unresected bronchial cancer, surgical resection should be encouraged even in patients with borderline cardiopulmonary function. Accurate estimation of the cardiopulmonary reserve is therefore desirable to avoid denying potentially curative treatment on the on hand and severe postoperative disability on the other. Various parameters (lung volumes, gas exchange, pulmonary hemodynamics, exercise endurance) are reviewed concerning their predictive values to evaluate functional operatibility. No ideal test exists. During exercise both pulmonary and cardiac risk can be evaluated simultaneously. The high predictive value of maximal oxygen uptake to assess postoperative morbidity and mortality is established. The postoperative values for the forced expiratory volumes, the transfer factor, and maximal oxygen uptake can be predicted by means of quantitative lung scans. A new four-stage algorithm for the functional evaluation is presented. Patients with normal lung function and exercise electrocardiography can undergo lung resection up to a pneumonectomy without further diagnostic procedures. In others, first the predicted postoperative values of forced expiratory volume and transfer factor should be estimated by taking into account the number of segments to be resected. Patients with values < 30% predicted are regarded as inoperable, whereas values > 40% predicted quality for resection without the need for further diagnostics. Patients with values between 30-40% predicted are further differentiated with cardiopulmonary exercise testing and for those cases where diagnostic uncertainty still remains, predicted postoperative values can be calculated using quantitative lung scans.

Carcinoma, Bronchogenic↗
PubMed1999

[Risk assessment of patients before lung surgery].

Lung resection offers the best prospect of long-term survival in patients with nonmetastatic pulmonary neoplasia. In view of the dismal prognosis of unresected bronchial cancer, surgical resection should be encouraged even in patients with reduced cardiopulmonary function. Accurate estimation of the postoperative cardiopulmonary function is therefore desirable to avoid (a) refusal of potentially curative treatment and (b) severe postoperative disability. The origins of post-resection morbidity and mortality are multifactorial. Thus, no single pulmonary function test or hemodynamic measurement can accurately and reliably predict postoperative cardiorespiratory complications. Criteria of functional operability should be based on percent of predicted value, so that patient's age, sex, and height will be taken into consideration. Exercise testing offers the advantage that both pulmonary and cardiac risk can be evaluated simultaneously. The high predictive value of maximal oxygen uptake (VO2max) in assessing postoperative morbidity and mortality is established. The calculation of predicted postoperative lung function (ppo) is of importance. The postoperative values for the forced expiratory volume in one second (FEV1-ppo), the transfer factor (TL,CO-ppo), and VO2max-ppo can be predicted by using the same formula. Patients with nearly normal lung function (FEV1, TL,CO > 75% predicted) and no concomitant cardiac disease can undergo lung resection right up to pneumonectomy without further diagnostic procedures. In the others, FEV1-ppo and TL,CO-ppo should be estimated first by taking into account the number of segments to be resected. Patients with values < 30% predicted are usually regarded as being inoperable, whereas values > 40% predicted qualify for resection without the need for further diagnostics. VO2max < 10 ml/kg/min or < 40% predicted are prohibitive for surgery. If VO2max is > 20 ml/kg/min or > 75% predicted, functional operability without limitation is given. For those cases where diagnostic uncertainty still remains, FEV1-ppo, TL,CO-ppo, and VO2max-ppo can be calculated by means of quantitative lung scans. Patients with either FEV1-ppo and TL,CO-ppo < 30% predicted or VO2max-ppo < 8 ml/kg/min or < 35% predicted are deemed inoperable.

Exercise Test↗