Determination of the concentration dependence of polyelectrolyte diffusion coefficients by application of the Boltzmann gradient method.

The concentration dependence of a polyelectrolyte diffusion coefficient in aqueous low salt solution (KCl, 1 mM) is determined from a single dynamic gradient experiment. The Boltzmann method is applied to calculate the diffusion coefficient. A special diffusion cell is constructed that minimizes aberrations in the optical detection of the polyion concentration profile. Bovine serum albumin (BSA) is chosen as a model polyion. To get information about the diffusion process down to very small polyion concentrations, the BSA molecule is fluorescently labeled. The fluorescence intensity is used as a measure of the polyion concentration. The change of the polyion net charge caused by labeling is discussed. The cell is illuminated by an LED, and the fluorescence intensity profile is detected by a CCD camera. Experiments at 5 and 17 degrees C show that the diffusion coefficient of labeled BSA remains constant in the very low polyion concentration range below a threshold of about 1.5 g/l. This is in contradiction to the linear concentration dependence of polyion diffusion coefficients at very low concentrations often postulated in the literature without reference to direct experimental evidence. Our finding is confirmed by dynamic light scattering experiments published recently. An explanation for this behavior based on a modified Donnan osmotic compressibility approach is given.

Selectivity and dynamic behavior of glass electrodes.

Two types of models are presently used to describe the potential of a glass electrode: the ion exchange type, which is based on the equilibrium binding ratio of the glass surface, and the permeability type, based on the permeability ratio of the ions within the glass matrix. It is shown that the permeability type models can be derived from first physical principles while the exchange type models are questionable from the physical point of view. The derivation of the potential-concentration behavior shows that the steady-state characteristic of the electrode potential is determined by the selectivity properties of the dry glass layer. The rapidity of the potential response of the glass electrode can be traced back to the fact that, under certain constraints regarding the diffusion coefficients, the potential difference across this layer only depends on the boundary concentrations. The potential drift, in contrast, is determined by ion transport in the hydrated surface layers of the electrode. The theoretical predictions of single- and multi-layer permeability models are compared with experimental data for a sodium selective electrode.

[Rare tumors of the parotid gland. Lymphadenoma of a sebaceous gland and extracranial metastasis from glioblastoma]. / Seltene Parotistumoren. Talgdrüsenlymphadenom und extrakranielle Glioblastommetastase.

Tumors of the parotid gland can be benign or malignant lesions.The pathophysiology of rare tumors of the parotid gland is often not sufficiently explored in this paper two rare histological entities are described. In one patient a benign sebaceous lymph-adenoma was histologically diagnosed. This type of tumor accounts for only 0.196 of all adenomas. The international literature is not conclusive about whether the tumor originates in the parotid gland itself or in the parotid lymph nodes. The second patient presented with a metastasis from a glioblastoma in the parotid gland. Again, the mechanism for metastasis of an intra-cerebral tumor to the parotid gland remains unknown. Iatrogenic seeding during a neurosurgical intervention is a probable explanation. The actual clinical course of his patient and the cases described in literature render surgical removal of such a metastasis questionable.

[Primary adenocarcinoma of the left atrium mimicking benign myxoma]. / Primäres Adenokarzinom des linken Herzvorhofes. Erst die Histologie führt zur Diagnose Adenokarzinom des Herzens.

Primary tumors of the heart are rare, whereas cardiac metastases, most frequently from adenocarcinomas, occur in up to 20% of malignant tumors. We report about a 61-year-old female patient who was admitted with recurrent stress-induced dizziness, intermittent tachycardia and a fall due to a pre-syncope. Echocardiography showed a left atrial tumor with the typical features of a pediculated myxoma, leading to open heart surgery. However, histopathology revealed a 2.2 x 1.5 cm adenocarcinoma. The subsequent search for a primary tumor, including tumor markers and (18)F-FDG-PET, was unsuccessful, as was a second thorough diagnostic workup half a year later. The tumor was therefore classified as a primary cardiac adenocarcinoma.

Seltene Parotistumoren : Talgdrüsenlymphadenom und extrakranielle Glioblastommetastase.

Tumors of the parotid gland can be benign or malignant lesions. The pathophysiology of rare tumors of the parotid gland is often not sufficiently explored. In this paper two rare histological entities are described.In one patient a benign sebaceous lymphadenoma was histologically diagnosed. This type of tumor accounts for only 0.1% of all adenomas. The international literature is not conclusive about whether the tumor originates in the parotid gland itself or in the parotid lymph nodes.The second patient presented with a metastasis from a glioblastoma in the parotid gland. Again, the mechanism for metastasis of an intracerebral tumor to the parotid gland remains unknown. Iatrogenic seeding during a neurosurgical intervention is a probable explanation. The actual clinical course of this patient and the cases described in literature render surgical removal of such a metastasis questionable.

The expression of cathepsins in osteoclast-like giant cells of an anaplastic thyroid carcinoma with tracheal perforation.

Anaplastic carcinoma of the thyroid gland (ACT) is a rapidly growing neoplasm with a very poor prognosis. In this study, we examined an ACT with osteoclast-like giant cells expressing matrix--degrading cysteine proteinases and their endogeneous inhibitor cystatin C. Bronchoscopic evaluation of a 50-year-old man suffering from hoarseness, dysphagia, and dyspnea revealed an irregular tumor mass infiltrating into the trachea and the cricothyroid ligament region. On histological examination, a necrotizing undifferentiated anaplastic carcinoma with osteoclast-like giant cells was detected. An immunohistochemical study of the tumor tissue was performed using a panel of 15 antibodies, including double labeling techniques. Most of the osteoclast-like multinucleated giant cells (MGC) expressed CD68 and cathepsin K. Colocalization of cathepsin B and its endogenous inhibitor cystatin C occurred in the majority of MGC. Mononuclear cells (MC) were positive for cathepsin B, cystatin C, and CD 68, but only faintly for cathepsin K. Expression of cathepsins B and K in the MGC of the ACT might contribute to the invasive behavior of this tumor, thus promoting metastatic ability and destruction of the cartilagenous trachea.

[Lymphoma-simulating presentation of focal nodular hyperplasia (FNH) of the liver]. / Eine lymphomähnliche Präsentation einer fokalen nodulären Hyperplasie (FNH) der Leber.

UNLABELLED: A 51-year-old woman, who had taken oral contraceptive drugs for 11 years, was referred to our Unit for examination of an asymptomatic 3.6 x 4.1 cm hypoechoic liver mass found by ultrasound examination carried out in the course of gynecological screening. INVESTIGATIONS: Laboratory evaluation revealed mild elevated liver enzymes. Computed tomography exhibited a hypervascularized lesion in segment 4 of the liver resembling a hemangioma or focal nodular hyperplasia but FNH was favored since magnetic resonance imaging showed a central scar within the hepatic lesion. Hepatobiliary scintigraphy was not typical thus an ultrasound-guided needle biopsy was performed. Histological examination revealed lymphoma-like infiltrates close to normal liver cells. However, the molecular biological examination showed oligoclonality of the infiltrating T-cells. Blood examinations, bone-marrow punctuation and CT thorax scan did not show any other lymphoma-like lesion. TREATMENT AND COURSE: After 5, 10 and 15 months the untreated patient was re-examined by MRI. The focal lesion showed an unchanged size and again a FNH-typical imaging. Liver-specific contrast enhancement was not suggestive for lymphoma. The lymphocytes were interpreted as an atypical lymphoid inflammatory infiltrate of a non-neoplastic lesion of the liver. CONCLUSIONS: The focal nodular hyperplasia can be a very difficult diagnosis in imaging and histopathological examinations. The lymphoma of the liver can be a rare but possible differential diagnosis.

Heterozygosity for the hemochromatosis gene in liver diseases--prevalence and effects on liver histology.

BACKGROUND/AIMS: The effect of heterozygosity for the C282Y mutation in the HFE hemochromatosis gene on iron accumulation and disease progression in liver disease patients is unclear. METHODS: We investigated the prevalence of this mutation in 531 patients and 205 healthy controls. In addition, we assessed the influence of the mutation on liver histology in 34 C282Y heterozygous and 124 age-, sex- and disease-matched controls without the mutation using the modified HAI and Chevallier score. RESULTS: The highest prevalence of the C282Y mutation was observed in patients with autoimmune hepatitis (17.2%, p<0.01) compared to 6.4% in healthy controls. Heterozygotes with hepatitis C and B virus infection showed higher ferritin and hepatic iron concentrations than patients without the mutation. However, we did not detect significant differences in necroinflammatory or fibrosis scores between carriers of the mutation and controls. CONCLUSIONS: There are marked differences in the prevalence of the C282Y mutation in patients with different liver diseases, with the highest prevalence rates in autoimmune hepatitis and PBC. However, the C282Y mutation alone only leads to a mild increase in iron accumulation in the majority of the patients, with the exception of H63D/C282Y compound heterozygotes. We found no evidence for more pronounced fibrosis in C282Y heterozygotes.

Hepatocellular carcinoma in a patient with hereditary hemochromatosis and noncirrhotic liver. A case report.

A case of a 62-year-old patient with hereditary hemochromatosis is reported, who developed hepatocellular carcinoma (HCC) in the absence of cirrhosis and other potential risk factors for HCC. Occurrence of HCC in patients with genetic hemochromatosis and noncirrhotic liver is a rare event which has previously been described only six times and appears to be limited to male patients.

[Littoral-cell angioma--a rare differential diagnosis on splenic tumors]. / Uferzellangiom--eine seltene Differentialdiagnose von Milztumoren.

UNLABELLED: HISTORY AND PRE-ADMISSION FINDINGS: Routine abdominal sonography of a 51-year-old man 6 years after removal of the right testis and radiotherapy for a seminoma revealed a 3 cm mass within the spleen. INVESTIGATIONS: All biochemical tests were normal. Computed tomography (CT) and magnetic resonance imaging confirmed the tumour which had not been present on the CT before the seminoma had been treated. No other space-occupying lesions were found in the thorax and abdomen. TREATMENT AND COURSE: A splenectomy was performed because a metachronous metastasis of the seminoma was suspected. The operation and subsequent course were uneventful. At operation the tumour had been diagnosed as an haemangioma because of its gross appearance, but histological and immunohistochemical examination revealed a littoral cell angioma. CONCLUSION: The littoral cell angioma is a benign vascular lesion in the red pulp of the spleen, which may be caused by different stimuli such as chronic infection or tumours. This case illustrates, that this tumour should be considered in the differential diagnosis of an unclear neoplasm in the spleen.

The anatomical basis of anal endosonography. A study in postmortem specimens.

PURPOSE: Anal endosonography is an imaging modality new to the diagnostic workup of incontinence. Interpretations even of normal endosonomorphologic findings now vary considerably. The conjoined longitudinal muscle (LM), a widely ignored structure, has until recently not been fully recognized by anal endosonography. The aim of this study, therefore, was to accurately determine the normal anatomy of the anal canal and correlate it with the findings obtained by anal endosonography. METHODS: Eight postmortem specimens of the anal canal were examined by endosonography. The findings were correlated with macroscopical dissection and gross sectional histology of the same specimens. RESULTS: The external echogenic ring is composed of two anatomical structures: the LM and the external anal sphincter (EAS). However, during anal endosonography the LM cannot always be differentiated from the EAS. Histologically, the relation of the diameters of the LM and the EAS ranged from 0.45:1 to 1.25:1. The narrow hyperechogenic ring between the inner hypoechoic layer and the external hyperechoic ring is an artificial finding that cannot be related to a distinct anatomical structure and most likely represents a sonographic interface. CONCLUSIONS: This study exactly outlines the relation of diameters of the conjoined longitudinal muscle and external anal sphincter for the first time. Until now, the LM has been underestimated in its dimensions. The role of such a thick muscular structure should be included in the conception of anal continence in the future. Especially in view of the fact that anal endosonography is increasingly used in the diagnostic workup of incontinence and fistula in ano, it is essential to understand the anatomical basis of endosonography. This study accurately delineates the sonomorphology of the anal muscles. When viewed in light findings reported here, endosonographic findings in diseases of the anal canal are nor based on a correct idea of the correlation between endosonomorphology and anal anatomy.

Histological determinants of the vascular surface in prostatic carcinoma.

This study was performed to analyse the correlation between vascular surface (VS), tumour grade and stage and relative proportion of tumour cells within the tumour stroma. Specimens of 41 prostatic carcinoma were immunostained using Factor VIII-related antigen. The VS was assessed by means of stereology. In tumour-free prostatic tissue the VS was 6.7 +/- 0.4 mm-1. In pT2 tumours this value was significantly increased to about 12 mm-1. With rising pT stage the VS significantly decreased to values of 4 in pT4 tumours. In G1 tumours the VS was 14.6 mm-1 and significantly decreased with decreasing grade of differentiation. No significant difference was obtained between pN0 and pN+ cases. A close positive correlation (r = 0.59, P < 0.001) existed between the VS and the relative proportion of tumour cells within the tumour, whereas a strong negative correlation was found between the VS and the relative amount of tumour stroma (r = 0.81, P < 0.001). The VS mainly depends on tumour differentiation and pT stage, i.e. the tumour size and the relative proportion of stroma and tumour cells within the tumour. These results are consistent with those obtained in experimental tumours. Assessment of the VS is therefore of interest in studies of tumour biology; it is of no use in predicting lymph node metastasis.

[The longitudinal muscle of the anal canal]. / Der longitudinale Muskel des Analkanals.

The longitudinal muscle (LM) represents a strong muscular structure of the anal canal situated between the internal (IAS) and the external anal sphincter (EAS). Terminal fibres of this muscle insert at the submucosa of the anal canal, representing the m. canalis ani. Others cross the subcutaneous part of the EAS to become the m. corrugator ani. Thus, the LM connects the visceral and somatic parts of the anal sphincter complex. Histologically ganglionic cells and as Vater-Pacinian corpuscles can be identified inside the LM. Morphology, topography and histology of the LM suggest that this muscle participates in maintaining anorectal continence. It is mandatory that the exact functions of this muscular structure be to elaborated upon, if we are to understand the mechanism of anorectal continence.

Assessment of the vascularization in prostatic carcinoma: a morphometric investigation.

Prostatic carcinoma obtained from 41 patients (pT2N0, 5; pT2N+, 2; pT3N0, 16; pT3N+, 16; pT4N0, 1; and pT4N+, 1) ranging from 45 to 79 years of age were investigated in the present study. A total of 410 tumor areas of different grades were analyzed (G1, n = 116; G2, n = 98; and G3, n = 196). Vascular structures were labeled immunohistochemically using factor-VIII-associated antigen. The vascular surface density (VSD), the microvessel number (NVES), and the maximum microvessel number (NVES-MAX) were assessed by means of stereology, and the results were related to tumor stage, nodal status, and grade of differentiation. NVES and NVES-MAX showed a significant increase with rising pT stage ranging from 25.5 +/- 1.48 in controls to 135.0 +/- 5.5 microvessels/mm2 in pT4 tumors. Discrimination of different pT stages was more accurate with NVES-MAX. The VSD was significantly higher in pT2 tumors compared with controls, whereas there were no significant differences between pT3 tumors, pT4 tumors, and controls, although the values in pT3 and pT4 tumors were distinctly lower than in pT2 tumors (P < .05). The VSD and the NVES were not able to discriminate between the pN0 and the pN+ group. Both parameters were slightly higher in patients with metastatic disease. Only NVES-MAX values differed between the two groups with an average of additional 21 microvessels/mm2 in the pN+ group (P < .05). Concerning the grade of tumor differentiation the VSD continuously decreased from G1 (14.58 +/- 2.24 mm(-1) to G3 tumor areas (5.41 +/- 1.46 mm(-1). Only G1 tumors showed significant differences compared with controls (6.65 +/- 0.38 mm(-1). The NVES increased with rising tumor grade with significant differences between all four groups ranging from 25.5 +/- 1.5 in controls to 136.9 +/- 37.2 microvessels/mm2 in pT4 tumors.

Quantitative assessment of vascular surface density in renal cell carcinomas.

OBJECTIVE: To evaluate the extent of vascularization by assessing vascular surface density in renal cell carcinomas (RCCs) of different nuclear grades, and in normal renal cortex and medulla. MATERIALS AND METHODS: Specimens of 79 RCCs of different nuclear grades (16 of G1, 42 of G2 and 21 of G3) were immunostained with the lectin Ulex europaeus agglutinin-I (UEA I). The vascular surface density of tumour tissue was assessed stereologically using a test grid at x400 magnification and compared to the values obtained in normal renal tissue. RESULTS: G3 tumours had a lower vascular surface density than had G1 and G2 RCCs and normal renal tissue of the cortex and medulla (P < 0.001, respectively). G1 tumours had a significantly higher vessel density than had normal medullary parenchyma and G2 carcinomas (P < 0.001). Vessel density was not significantly different among G1 tumours and cortical parenchyma in controls and among normal medullary tissue and G2 tumours. Statistical analysis showed that the vascular surface density was independent of tumour stage and size and the age and sex of the patients. CONCLUSION: The degree of vascularization in RCCs decreased with their grade of differentiation, suggesting that the extent of neovascularization in tumour tissue reflects the relationship between tumour cell proliferation and vascular growth. The values of vascular surface density in normal renal tissue of the cortex and medulla partially overlapped with those obtained in tumour tissue.

Nuclear morphometry of renal cell carcinomas.

In this study, the correlation between different morphometric nuclear parameters and grading of renal cell carcinoma was investigated. Nuclear area, the standard deviation of the nuclear area and the form factor (FF) were assessed using a computer assisted image analyzer system. A statistically significant difference between G2 and G3 carcinomas could be confirmed for the nuclear area and the standard deviation of the nuclear area, with the significance level being lower for the latter parameter. Normal tubular epithelia and G1 carcinomas showed no significant difference in the nuclear area and the standard deviation of the nuclear area. In contrast, the form factor discriminated between normal tubular epithelium and G1 carcinomas, whereas no difference of the FF between G2 and G3 carcinomas was found. Reclassification of the subjectively assessed tumor grading was performed by means of linear discriminant analysis using all possible combinations of the different nuclear parameters. This procedure disclosed an increasing rate of correctly reclassified grading with rising number of parameters applied. We conclude that the isolated assessment of nuclear area does not suffice for the correct morphometric tumor grading, and that further parameters describing the nuclear shape have to be applied additionally in studies concerning morphometric nuclear grading.

[Nematode larva migrans. On two cases of filarial infection]. / Wandernde Nematodenlarven. Uber zwei Fälle von Filarienbefall.

With rapid air travel, so-called parasitic infections are becoming more important in northern hemisphere and temperate climates. Parasitic disease is usually taken to imply infections caused by protozoa and helminths. The most important helminthic infections in man and with world-wide incidence are schistosomiasis, hookworm, and filariasis. We report the clinico-pathological findings of two patients with filarial infection of soft tissue and lymphatic nodes.

Kinetic coupling between protein folding and prolyl isomerization. I. Theoretical models.

Kinetic models were developed to describe the influence of prolyl peptide bond isomerization on the kinetics of reversible protein folding for cases in which structural intermediates do not occur. In the simulations, the number of prolyl residues and the relative rates of folding and isomerization were varied. The experimentally observed rate constants were found to be identical with the intrinsic rate constants of folding and isomerization only when folding remains much faster than prolyl isomerization throughout the transition region. When the rate of folding becomes similar to or lower than the rate of isomerization, the observed kinetic parameters are complex functions of all microscopic rate constants. In particular, the observed folding rates in the transition region decrease with the number of prolyl residues. Pseudo two-state kinetics with single folding and unfolding reactions are observed in several cases, although the apparent folding rates depend strongly on prolyl isomerization reactions in the unfolded chain. This virtual simplicity can easily lead to misinterpretation of kinetic data. Additional phases can be resolved when refolding is started from the fast-folding species (UF). The coupling between folding and prolyl peptide bond isomerization also modifies the dependence on denaturant concentration of the apparent rate constants of folding. We suggest several tests to detect and characterize the contributions of folding and isomerization steps to the observed folding kinetics.

Protein aggregation in vitro and in vivo: a quantitative model of the kinetic competition between folding and aggregation.

Protein aggregation is frequently observed as a major side-reaction of protein folding. We present quantitative models explaining the formation of aggregates during protein folding in vitro and in vivo on the basis of a kinetic competition between correct folding and aggregation reactions. Both models are in good agreement with experimental data. The model implies that, in vitro, the yield of native protein obtained upon refolding is determined by the rates of the competing first order folding and second order aggregation reactions. Therefore, a high protein concentrations aggregation dominates over folding and leads to the formation of insoluble protein. For in vivo protein synthesis, the model shows that the yield of native protein is only dependent on the rate of folding, on the rate of aggregation and on the rate of protein synthesis. In the cell, several mechanisms, including "folding helpers" seem to have evolved, which influence these processes and thereby prevent unproductive side reactions.