Electron microscopy and capillaroscopically guided nailfold biopsy in connective tissue diseases: detection of ultrastructural changes of the microcirculatory vessels

The aims of the study were to describe and compare the frequency and nature of histologically detectable microvascular lesions in patients with various connective tissue diseases (CTD). An electron microscopic examination of specimens obtained by the technique of capillaroscopically guided nailfold biopsy was performed in 52 patients with CTD [nine systemic lupus erythematosus (SLE), eight mixed CTD, 18 scleroderma, 17 undifferentiated CTD] and 27 controls. The microvascular changes most frequently observed by electron microscopy were multilayering of the basal lamina (approximately 70% of the CTD patients), an increased amount of perivascular connective tissue, perivascular oedema formation, and an increased number of perivascular fibroblasts and mast cells (each in 30-37% of the CTD patients). In contrast, no particular histopathological feature was found in > 25% of the controls, multilayering (22.6%) being the most frequently observed. Comparing the different conditions studied, there were distinct differences in the frequency and nature of the histologically observed microvascular changes. In particular, SLE seems to be based on a separable type of vasculopathy consisting of significantly less frequent microvascular abnormalities. In conclusion, ultrastructural abnormalities of the microvascular system are a frequent finding in CTD. Electron microscopic examination of specimens obtained by capillaroscopically guided nailfold biopsy is able to disclose histopathological differences between defined entities. Therefore, this approach may be a useful tool to gain further insights into potentially separable aetiopathological mechanisms of the various types of CTD.

Ferredoxin reduction by photosystem I from Synechocystis sp. PCC 6803: toward an understanding of the respective roles of subunits PsaD and PsaE in ferredoxin binding

The process of ferredoxin reduction by photosystem I has been extensively investigated by flash-absorption spectroscopy in psaD and psaE deleted mutants from Synechocystis sp. PCC 6803. In both mutants, the dissociation constant for the photosystem I/ferredoxin complex at pH 8 is considerably increased as compared to the wild type: approximately 25- and 100-fold increases are found for PsaD-less and PsaE-less photosystem I, respectively. However, at high ferredoxin concentrations, submicrosecond and microsecond kinetics of electron transfer similar to that observed in the wild type are present in both mutants. The presence of these fast kinetic components indicates that the relative positions of ferredoxin and of the terminal photosystem I acceptor are not significantly disturbed by the absence of either PsaD or PsaE. The second-order rate constant of ferredoxin reduction is lowered 10- and 2-fold for PsaD-less and PsaE-less photosystem I, respectively. Assuming a simple binding equilibrium between photosystem I and ferredoxin, PsaD appears to be important for the guiding of ferredoxin to its binding site (main effect on the association rate) whereas PsaE seems to control the photosystem I/ferredoxin complex lifetime (main effect on the dissociation rate). The properties of electron transfer from photosystem I to ferredoxin were also studied at pH 5. 8. In the psaE deleted mutant as in the wild type, the change of pH from 8 to 5.8 induces a 10-fold increase in affinity of ferredoxin for photosystem I. In the absence of PsaD, this pH effect is not observed, in favor of this subunit being mostly responsible for the low pH increased affinity.

MEN1 gene mutations in 12 MEN1 families and their associated tumors

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited tumor syndrome characterized by the development of multiple endocrine tumors. The gene responsible for the disease, termed MEN1 gene. has recently been isolated and germline mutations have been described in affected MEN1 individuals. Twelve unrelated (German MEN1 families and their associated tumors (5 parathyroid tumors, 1 vipoma, 1 gastrinoma, 1 insulinoma) were characterized for MEN1 gene mutations by single-strand conformational variant (SSCV) analysis and DNA sequence analysis as well as for loss of heterozygosity on chromosome 11q13. We identified nine different heterozygous germline mutations (6 frameshift, 2 missense, 1 nonsense), eight of them were novel. Four of five informative MEN1-associated tumors revealed deletion of the second MEN1 allele, supporting the concept of a tumor suppressor gene. Furthermore. SSCV analysis proved an effective and sensitive method for the detection of menin mutations providing a reliable genetic screening approach supporting genetic counseling and clinical management of MEN1 family members.

An electrothermal atomic absorption spectrometer using semiconductor diode lasers and a tungsten coil atomizer: design and first applications

A new type of atomic absorption spectrometer using a laser diode as light source and a tungsten coil as atomizer is described. Compared to established atomic absorption spectrometers, it is much simpler in construction, smaller in size, and less expensive and it provides inherent background correction and high detection power. The performance of this concept is demonstrated by the determination of aluminum and chromium in water, blood serum and, using the slurry sampling technique, in powdered high-purity graphite and titanium dioxide samples. For calibration, the standard addition method was used. Possible interferences by impurities originating from the tungsten coils are discussed. Applying aqueous solutions of Al and Cr, detection limits of 0.9 and 0.03 ng/mL, respectively, were obtained, and for serum, they were 2.5 and 0.3 ng/mL, respectively. For these elements in graphite and titanium dioxide applied as slurry, the detection limits are between 0.02 (Cr in TiO2) and 0.6 micrograms/g (Al in graphite). The accuracy was checked by comparison of the results with those of other methods. The described system is especially suitable for on-site and on-line analysis.

Genomic organization and chromosomal localization of the human SGK protein kinase gene

The SGK protein kinase is a novel member of the serine/threonine protein kinase family. Its corresponding gene belongs to the group of immediate-early genes. SGK transcription is controlled by cell volume alterations in different cell lines. To analyze the genomic structure and chromosomal location of the SGK gene, a human P1 clone was isolated by screening a human genomic library with a SGK cDNA probe. This clone was confirmed to encode the authentic SGK gene by the detection of exon-intron structures and the correspondence between the nucleotide sequences of exons and human cDNA. Using this P1 clone as a probe for fluorescence in situ hybridization, a single chromosomal locus for SGK was assigned to band 6q23, a region frequently affected by deletion in various human neoplasms.

K-ras oncogene mutations indicate malignancy in cystic tumors of the pancreas

OBJECTIVE

To evaluate clinical parameters, presurgical diagnostic tests, histologic findings, and the presence of K-ras oncogene mutations in cystic tumors of the pancreas to determine which best predict malignancy.

SUMMARY BACKGROUND DATA

Because presurgical, intraoperative, and final pathologic differentiation is difficult in cystic tumors of the pancreas, it would be a major benefit to identify markers that accurately predict malignancy in these rare tumors. The role of K-ras oncogene mutations as an indicator of malignancy has not been determined in these tumors.

METHODS

Nineteen patients with cystic tumors of the pancreas were evaluated, including K-ras mutation analysis based on polymerase chain reaction and restriction digestion assays and direct DNA sequencing, to screen for parameters that accurately predict malignancy.

RESULTS

All malignant cystic pancreatic tumors (five cystadenocarcinomas and three mucin-producing adenocarcinomas) harbored K-ras mutations at codon 12 or 13. K-ras mutations were also detected in the percutaneous fine-needle aspirates of two of these patients. In contrast, none of nine benign cystadenomas or the solid-papillary neoplasm had K-ras mutations. None of the patients with a benign tumor carrying K-ras wild-type sequences developed recurrent disease after a mean follow-up of 50 months. Seven of the 8 malignant cystic pancreatic tumors, but none of the 11 benign tumors, showed dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography.

CONCLUSIONS

K-ras mutation analysis seems to be a powerful tool to determine the malignant potential of cystic pancreatic tumors before and after surgery. Dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography is highly suggestive for malignancy in these rare tumors.

Amitogenic alginates: key to first clinical application of microencapsulation technology

Microencapsulation refers to a technique of immunoisolation by coating single cells or tissue with a semipermeable membrane. By combining microencapsulation with a specific tissue culturing method, iso-, allo-, and xenotransplantation of parathyroid tissue has been achieved without immunosuppression in a long-term animal model. Prior to its clinical use, continued analyses of the alginate, used as a coating substance, determined its mitogenic properties. Purification of the commercially available alginate was achieved using patented electrophoretic procedures, resulting in an amitogenic alginate suitable for use in humans. However, this alginate exhibited entirely different physical properties. We have recently shown that isotransplanted parathyroid tissue remains vital and functioning in vivo over long periods of time using the novel amitogenic alginate. It is essential to document, whether the alginate is able to maintain immunoisolation. We have therefore assessed its in vivo function compared to the mitogenic alginate in a transgenic animal model. Altogether 600 parathyroid glands from 300 Lewis rats (donor animals) were excised and subjected to tissue culture. Thereafter they were allotransplanted to 30 parathyroidectomized Dark-Auita rats, microencapsulated with the amitogenic or the mitogenic alginate or naked, with 10 recipient animals in each group. Total serum calcium and parathyroid hormone levels were monitored continuously at weekly intervals for 30 weeks. After 26 weeks the transplant beds were excised and subjected to histologic examination. More than 6 months after allotransplantation 9 of 10 animals that had received amitogenic transplants, compared to 7 of 10 animals in the group with mitogenic microcapsules were normocalcemic. Animals that had received naked parathyroid tissue were hypocalcemic as soon as 2 weeks after allotransplantation. Correspondingly, normocalcemic animals showed vital parathyroid tissue inside the microcapsules, which were surrounded by a significantly smaller rim of fibroblasts when amitogenic alginate had been used. In addition to confirming physiologic long-term function, we were able to document for the first time that immunoisolation can also be achieved with the novel amitogenic alginate, which is suitable for clinical use.

Cloning of sgk serine-threonine protein kinase from shark rectal gland – a gene induced by hypertonicity and secretagogues

Recently, the cell-volume-regulated serine-threonine protein kinase h-sgk was cloned from a human hepatoma cell line. The sgk gene was shown to be induced by cell shrinkage in many different mammalian cell lines. In this study, two highly conserved serine-threonine protein kinases, sgk-1 and sgk-2, were cloned from rectal gland tissue of the spiny dogfish (Squalus acanthias). Both kinases showed a distinct pattern of tissue specificity, with high expression levels in kidney, intestine, liver and heart. In rectal gland slices sgk-1 transcription was induced by exposure to hypertonic solution, reduction of the extracellular urea concentration, and addition of the secretagogues vasoactive intestinal polypeptide (VIP) and carbachol. The shark sgk-1 serine-threonine protein kinase may therefore provide a link between cell volume, Cl–secretion and protein phosphorylation state in shark rectal gland cells.

Frequent abnormalities of the putative tumor suppressor gene FHIT at 3p14.2 in pancreatic carcinoma cell lines

The FHIT gene is localized on chromosome 3p14, a region including a tumor cell-specific, commonly deleted region. To determine the role of the FHIT gene in pancreatic carcinogenesis, 14 pancreatic carcinoma cell lines were analyzed by reverse transcription-PCR and exon-specific PCR amplification of genomic DNA. The full-length FHIT transcript was lost in 70% of the pancreatic carcinoma cell lines analyzed, while 66% also revealed intragenic homozygous deletions of exons 3, 4, and 5. Truncated FHIT transcripts lacking a variable number of exons most likely represented alternative splicing products. Fhit protein expression was dependent on a full-length FHIT transcript. The results suggest that the FHIT gene may be a target tumor suppressor gene involved in pancreatic carcinogenesis.

[Heterologous transplantation of human parathyroid glands after microencapsulation with clinically suitable alginate : long-term function without immunosuppression in the animal model]

The role of parathyroid transplantation for the therapy of permanent hypoparathyroidism is undisputed. Because the parathyroid hormone deficiency syndromee rarely every is a vital thread to patients affected, systemic immunosuppression for transplant recipients is not justified. A technique of microencapsulation was modified for transplantation of parathyroid tissue. Using a core substance suitable for clinical use (amitogenic alginate), we accomplished allotransplantation of functioning parathyroid tissue in the long-term animal model and, very recently, reported first clinical cases without postoperative immunosuppression. In a controlled animal model of totally parathyroidectomized rats (PTX, two groups of n = 40), we investigated the ability of microencapsulation with the amitogenic alginate to enable transplantation across the highest immunological barrier (xenotransplantation: human-rat); to ensure intact transplant function and to protect from rejection. Rat parathyroid hormone (PTHRA i.S.) and serum calcium levels served as parameters of completeness of PTX; intact human PTH (PTHRA i.S.) and serum calcium levels of recipient animals were used to assess graft function. Also, tissue integrity within explanted capsules was assessed by histology. Cultured and microencapsulated parathyroid tissue resumes and maintains function in vivo, even if transplanted across the highest immunological barrier. Functionally, PTHHU i.S. replaced (PTHRA i.S.) in PTX animals entirely and restored normocalcemia. These results suggest, that xeno-transplantation of the parathyroids can be achieved without postoperative immuno-suppression in a long term animal model. These data also imply the possibility of clinical heterotransplantation of parathyroid glands.

The species-specific structure of microanatomical compartments in the human spleen: strongly sialoadhesin-positive macrophages occur in the perifollicular zone, but not in the marginal zone

The microanatomical structure of human and rat splenic white pulp is compared, with special emphasis on the localization of the marginal zone occupied by immunoglobulin M (IgM)+ IgD-/dull B lymphocytes and its specialized macrophages. Our study reveals that in contrast to rats, the marginal zone of humans primarily exists in the vicinity of primary and secondary splenic follicles and that it is almost absent around the periarteriolar T-cell zones. We demonstrate that in humans there is an additional compartment, the perifollicular zone, located between the marginal zone and the red pulp. The perifollicular zone is a dynamic region of variable cellular and phenotypic composition, which can be regarded either as a part of the red pulp or of the follicles. In most cases the perifollicular zone appears as a compartment of the red pulp containing erythrocyte-filled spaces which differ from the typical red pulp sinusoids. Similar to the splenic cords, the perifollicular zone mostly harbours scattered B and T lymphocytes. However, sometimes B lymphocytes clearly predominate in the perifollicular area. In addition, strongly sialoadhesin-positive macrophages form sheaths around capillaries in the perifollicular zone. Such capillary sheaths are not observed in rats. In humans weakly sialoadhesin-positive macrophages are also present in the perifollicular zone and in the red pulp. In some specimens sialoadhesin is, however, strongly expressed by a large number of dispersed perifollicular macrophages. Interestingly, in striking contrast to rats, the human marginal zone does not contain sialoadhesin-positive macrophages and marginal metallophilic macrophages are also absent in humans. Thus, sialoadhesin-positive macrophages and IgM+ IgD- memory B lymphocytes both share the marginal zone as a common compartment in rats, while they occupy different compartments in humans. We show that the human splenic marginal zone does not contain a marginal sinus and assume that in humans the perifollicular region is the compartment where antigen and recirculating lymphocytes enter the organ.

First successful xenotransplantation of microencapsulated human parathyroid tissue in experimental hypoparathyroidism: long-term function without immunosuppression

Owing to the complexity of the parathyroid hormone's metabolic interactions, clinical hypoparathyroidism is one of the most difficult of all endocrine disorders to treat. Therefore, causative treatment of this disorder by transplantation of parathyroid glands is highly desirable. We have recently documented the long-term in vivo function of iso- and allotransplanted rat parathyroid tissue without systemic immunosuppression in an animal model. In view of the potential clinical use of this method, human parathyroid tissue has been microencapsulated and transplanted over the highest immunological barrier. In a controlled, long-term animal study in the parathyroidectomized rat, the effect of microencapsulation on xenotransplanted human parathyroid tissue was evaluated over 30 weeks (native and microencapsulated parathyroid tissue = 40 rats respectively). Functionally, human parathyroid tissue was able to replace that of the rat. All animals that had received microencapsulated parathyroid tissue were normocalcemic for 16 weeks; 27/40 at the end of the study. In contrast, serum calcium concentrations dropped to post-parathyroidectomy levels within 4 weeks in those animals that had received native tissue only. Histologic evaluation of the explanted, functionally successful xenografts showed vital parathyroid tissue inside intact microcapsules surrounded by a small rim of fibroblasts. Avital fibrotic remnants were demonstrated in animals with non-encapsulated parathyroid tissue. Thus, we have established the feasibility of microencapsulation of human parathyroid tissue, preserving its viability over long periods in vivo even if xenotransplanted. In combination with an improved tissue culture method, transplantation of human parathyroid tissue and maintenance of its physiological function is reproducibly achieved without postoperative systemic immunosuppression over the highest transplantation barrier. This may be a crucial step towards the first clinical application of this method.

A 'specificity' pocket inferred from the crystal structures of the complexes of aldose reductase with the pharmaceutically important inhibitors tolrestat and sorbinil

BACKGROUND

Aldose reductase (AR) is an NADPH-dependent enzyme implicated in long-term diabetic complications. Buried at the bottom of a deep hydrophobic cleft, the NADPH coenzyme is surrounded by the conserved hydrophilic residues of the AR active site. The existence of an anionic binding site near the NADP+ has been determined from the structures of the complexes of AR with citrate, cacodylate and glucose-6-phosphate. The inhibitor zopolrestat binds to this anionic site, and in the hydrophobic cleft, after a change of conformation which opens a 'specificity' pocket.

RESULTS

The crystal structures of the porcine AR holoenzyme and its complexes with the inhibitors tolrestat and sorbinil have been solved; these structures are important as tolrestat and sorbinil are, pharmaceutically, the most well-studied AR inhibitors. The active site of the holoenzyme was analyzed, and binding of the inhibitors was found to involve two contact zones in the active site: first, a recognition region for hydrogen-bond acceptors near the coenzyme, with three centers, including the anionic site; and second, a hydrophobic contact zone in the active-site cleft, which in the case of tolrestat includes the specificity pocket. The conformational change leading to the opening of the specificity pocket upon tolrestat binding is different to the one seen upon zopolrestat binding; this pocket binds inhibitors that are more effective against AR than against aldehyde reductase.

CONCLUSIONS

The active site of AR adapts itself to bind tightly to different inhibitors; this happens both upon binding to the inhibitor's hydrophilic heads, and at the hydrophobic and specificity pockets of AR, which can change their shape through different conformational changes of the same residues. This flexibility could explain the large variety of possible substrates of AR.

Cloning and characterization of a putative human serine/threonine protein kinase transcriptionally modified during anisotonic and isotonic alterations of cell volume

Hepatic metabolism and gene expression are among other regulatory mechanisms controlled by the cellular hydration state, which changes rapidly in response to anisotonicity, concentrative substrate uptake, oxidative stress, and under the influence of hormones such as insulin and glucagon. Differential screening for cell volume sensitive transcripts in a human hepatoma cell line revealed a gene for a putative serine/threonine kinase, h-sgk, which has 98% sequence identity to a serum- and glucocorticoid regulated kinase, sgk, cloned from a rat mammary tumor cell line. h-sgk transcript levels were strongly altered during anisotonic and isotonic cell volume changes. Within 30 min h-sgk RNA was, independent of de novo protein synthesis, induced upon cell shrinkage and, due to a complete stop in h-sgk transcription, reduced upon cell swelling. Comparable changes of sgk transcript levels were observed in a renal epithelial cell line. h-sgk mRNA was detected in all human tissues tested, with the highest levels in pancreas, liver, and heart. The putative serine/threonine protein kinase h-sgk may provide a functional link between the cellular hydration state and metabolic control.

Study of non-covalent enzyme-inhibitor complexes of aldose reductase by electrospray mass spectrometry

Specific non-covalent interactions between aldose reductase (AR), its NADP+ cofactor and five inhibitors have been characterized by electrospray mass spectrometry (ES-MS). These results indicated that the protein could be desorbed and maintained in the gas phase in a form very close to its native conformation. Collisionally induced dissociation (CID)-MS and CID-MS-MS showed that the adenosine diphosphate part of the cofactor interacts strongly with AR. The relative stability of the ternary AR x NADP+ x inhibitor complexes was established and successfully correlated with the IC50 values. All inhibitors were shown to only bind to AR holoenzyme. These results are important for the field of drug development insofar as ES-MS might provide a rapid and very sensitive method for the screening of potential drugs or for the identification of compounds displaying high binding affinity to a target biomolecule.

Investigation of aging in polymer networks by T1 rho material property NMR imaging

Material property (MAP) imaging was found to be a promising method for the investigation of aging processes in elastomer materials. Based on conventional parameter-selective imaging, MAP imaging directly reveals the properties of the material by use of a theoretical description to relate the measured nuclear magnetic resonance data--in this investigation, T1 rho values--with the properties of the material. Following this concept, T1 rho images with different strengths of lock amplitude have been acquired for a rubber sample consisting of four pieces of natural rubber that were oxidatively aged under different conditions. The data were analyzed using a defect-diffusion model and transformed into images of those material parameters, which were found to be suitable for the characterization of the aging process. Images correlating with the crosslink density and the power law of T1 rho dispersion were obtained indicating the degree of aging.

Transplantation of parathyroid tissue in experimental hypoparathyroidism: in vitro and in vivo function of parathyroid tissue microencapsulated with a novel amitogenic alginate

Microencapsulation of tissues is an alternative to postoperative immunosuppression in transplantation. In 1994 iso-, allo- and xenotransplantation of microencapsulated parathyroid tissue was achieved in vivo. However, continued analysis of the coating substance (an alginate) determined mitogenic properties. Here, we report on the in vitro and in vivo function of parathyroid tissue microencapsulated with a novel amitogenic alginate suitable for use in humans. To assess in vitro function, parathyroid tissue encapsulated with mitogenic and amitogenic alginate was exposed to rising concentrations of calcium. For in vivo experiments, it was isotransplanted into parathyroidectomized rats. PTH release into medium and PTH serum levels as well as calcium levels of recipient rats were analyzed and compared to native (non-microencapsulated) tissue and empty capsules, respectively. In vivo, transplants were excised and subjected to histologic examination six months after trans-plantation. In vitro, parathyroid tissue encapsulated with amitogenic alginate releases approximately half of the PTH of the native tissue, not different from tissue encapsulated with the mitogenic alginate. In vivo, the novel alginate preserved parathyroid function similar to that of native tissue over the six month period resulting in complete reversal of hypoparathyroidism. Correspondingly, histologic examination revealed vital parathyroid tissue in intact microcapsules. By establishing in vitro function and successful long-term transplantation, we have documented the principle of microencapsulation of parathyroid tissue to be effective also with the novel amitogenic alginate, which is suitable for clinical use.

Tyrosine phosphorylation-dependent suppression of a voltage-gated K+ channel in T lymphocytes upon Fas stimulation

Selective cell death plays a critical role in the development of the immune system and in the elimination of target cells expressing foreign antigens. Most of programmed cell death occurs by apoptosis. Apoptotic cell death of lymphocytes can be triggered by ligation of APO-1/Fas (CD95) antigen (Suda, T., and Nagata, S. (1994) J. Exp. Med. 179, 873-879; Nagata, S., and Golstein, P. (1995) Science 267, 1449-1456). We find that activation of Fas leads to the inhibition of the voltage-dependent n-type K+ channels (Kv1.3) studied by patch clamp technique in Jurkat T lymphocytes. Tyrosine kinases have been shown to be crucial in Fas-induced cell death (Eischen, C. M., Dick, C. J., and Leibson, P. J. (1994) J. Immunol. 153, 1947-1954). The inhibition of the current is correlated with the tyrosine phosphorylation of immunoprecipitated and blotted K+ channel protein. We show, that the Src-like protein-tyrosine kinase inhibitor herbimycin A and the deficiency of the p56(lck) tyrosine kinase in mutant Jurkat cells abolished the channel inhibition and phosphorylation by anti-Fas antibody, while reconstitution of the p56(lck) kinase partly restored these effects of Fas receptor triggering. These results suggest a regulation of n-type K+ channels by tyrosine kinases upon Fas receptor triggering, which might be important for apoptosis.

Characterization of elastomeric materials by NMR-microscopy

This review reflects a long experience with the application of NMR-imaging methods to elastomeric materials. The experimental techniques, used to obtain parameter selective NMR images (T1, T2, T1 rho-images), are described in detail and the methods required for the data analysis are explained. A special emphasis is put on the analysis of experimental errors within the framework of NMR-imaging. In order to make parameter selective images generally useful their information should be correlated to material properties, so that images of the material properties can be obtained. This is demonstrated for the case of crosslink density, which is certainly one of the molecular properties in rubber materials, exhibiting the main influence on mechanical and other material properties. Sulfur cured and carbon black filled technical rubbers with different degree of crosslink density and oxidative aging were investigated using parameter selective in aging techniques. The image data were analyzed by means of gaussian and multiexponential fitting procedures, revealing spatially resolved NMR relaxation parameters. The further interpretation of these parameters was based on physical models describing molecular motions in crosslinked polymers.

Expression of vitamin D receptor in lung cancer

The active metabolite of vitamin D 1,25-dihydroxycholecalciferol is a hormone-like agent that regulates cell differentiation and proliferation. Various vitamin D derivatives have been shown to induce differentiation in neoplastic cells. The prerequisite for any hormone action is the presence of its receptor. We studied the expression of vitamin D receptor in human lung cancer cell lines and in primary lung cancer tissue. Employing the polymerase chain reaction, 10 out of 11 cell lines stemming from small-cell lung cancer and 15 out of 15 cell lines stemming from non-small-cell lung cancer demonstrated vitamin D receptor expression. An immunohistochemical analysis, using a specific monoclonal antibody, demonstrated vitamin D receptor protein expression in 31 out of 117 (26%) primary small-cell lung cancer cases tested. Positive cells exhibited a nuclear reaction pattern. Twenty-one out of 37 primary non-small-cell lung cancer cases, particularly adenocarcinomas (9/14) and squamous-cell carcinomas (10/15), exhibited vitamin D receptor. Results indicate that a subset of lung cancer cases may be susceptible to the differentiating effects of vitamin D analogues.

NMR studies on water and polymer diffusion in dextran gels. Influence of potassium ions on microstructure formation and gelation mechanism

At room temperature aqueous solutions of dextrans with concentrations > 25% (w/w) exhibit a sol-gel transition in the presence of > 1.0 M potassium chloride. In dextrans the gelation was unexpected due to missing anionic groups that usually provide the binding sites for cations. The quantitative investigation of the gel formation is based on changes of the diffusibility of water and dextran chains. The apparent diffusion coefficients of bulk water (in the order of 10(-6) cm2/s) and of water trapped in the junction zones as well as of polymer chains (in the order of 10(-7) to 10(-8) cm2/s) are determined by employing pulsed field gradient stimulated echo (PFGSTE) NMR. The restricted diffusion of bulk water in viscous sols and in soft and rigid gels has been quantitatively analyzed providing data for interbarrier distances (pore size), permeabilities of the diffusion barriers (density of junction zones) and interbarrier diffusion coefficients of water. Based on already published x-ray structure data and in accordance with the diffusion data presented in this paper "potassium-bonding" is assumed to be the most important interaction for the formation of a microstructure and for the stabilization of cross-links. The ionic radius of the potassium ion perfectly fits to the cage established by six oxygen atoms of glucose units of three polymer chains. Other cations, such as Li+, Na+, Rb+ and Cs+, according to their nonfitting ionic radii, do not provoke dextran gelation under these conditions. The mechanism of the transitions from sol to soft gel and further to rigid gel is discussed on the basis of restricted diffusion and x-ray structure data.

[Subacute distal motor neuropathy disclosing malignant non-Hodgkin lymphoma: improvement under chemotherapy]

A non Hodgkin's lymphoma strictly located in the bone marrow, was discovered in a patient presenting with asymetric muscle weakness of upper and lower limbs. Both the lymphoma and the neurological syndrome were successfully treated with chemotherapy.