Polymer-coated PtCo nanoparticles deposited on diblock copolymer templates: chemical selectivity versus topographical effects.

Metal-polymer hybrid films are prepared by deposition of polymer-coated PtCo nanoparticles onto block copolymer templates. For templating, a thin film of the lamella-forming diblock copolymer poly(styrene-b-methyl methacrylate) P(S-b-MMA) is chemically etched and a topographical surface relief with 3 nm height difference is created. Two types of polymer-grafted PtCo nanoparticles are compared to explore the impact of chemical selectivity versus the topographical effect of the nanotemplate. A preferable wetting of the polystyrene (PS) domains with poly(styrenesulfonate) (PSS)-coated PtCo nanoparticles (instead of residing in the space between the domains) is observed. Our investigation reveals that the interaction between PSS-coated nanoparticles and PS domains dominates over the topographical effects of the polymer surface. In contrast, a non-selective deposition of poly(N-vinyl-2-pyrrolidone) (PVP)-coated PtCo nanoparticles and the formation of large metal-particle aggregates on the film is observed.

Intraocular epiretinal prosthesis to restore vision in blind humans.

Visual sensations in blind patients suffering from retinal degenerations may be restored by electrical stimulation of retinal neurons using implantable microelectrode arrays. The EPI-RET-3 project was initiated to evaluate a wireless intraocular retinal implant system for human use in terms of safety and efficiency. The implant is a remotely controlled fully intraocular prosthesis consisting of a receiver and a stimulator module. The stimulator is placed onto the retina's surface. Data and energy are transmitted via an inductive link from outside the eye to the implant. The EPI-RET-3 device was implanted into six legally blind patients with Retinitis Pigmentosa (RP) for a period of four weeks. The surgery was performed without complications. The implants were activated on days 7, 14 and 27 after implantation. All patients reported visual sensations such as dots, arcs, or lines of different colours and intensities. The required stimulation thresholds were found to be very low. Implantation of the wireless EPI-RET-3 device is safe and the system is suitable to elicit visual sensations in blind RP patients. Major problems in the design and fabrication of a prosthesis for artificial vision could be solved in this approach.

Restoring visual perception using microsystem technologies: engineering and manufacturing perspectives.

Microsystem technologies offer significant advantages in the development of neural prostheses. In the last two decades, it has become feasible to develop intelligent prostheses that are fully implantable into the human body with respect to functionality, complexity, size, weight, and compactness. Design and development enforce collaboration of various disciplines including physicians, engineers, and scientists. The retina implant system can be taken as one sophisticated example of a prosthesis which bypasses neural defects and enables direct electrical stimulation of nerve cells. This micro implantable visual prosthesis assists blind patients to return to the normal course of life. The retina implant is intended for patients suffering from retinitis pigmentosa or macular degeneration. In this contribution, we focus on the epiretinal prosthesis and discuss topics like system design, data and power transfer, fabrication, packaging and testing. In detail, the system is based upon an implantable micro electro stimulator which is powered and controlled via a wireless inductive link. Microelectronic circuits for data encoding and stimulation are assembled on flexible substrates with an integrated electrode array. The implant system is encapsulated using parylene C and silicone rubber. Results extracted from experiments in vivo demonstrate the retinotopic activation of the visual cortex.

Image acquisition and image processing for the intraocular vision aid.

The contribution describes an "intraocular vision aid (IOVA)" system for patients suffering from corneal opacification. In order to gain patients' acceptance the system has to be miniaturized to a magnitude that image acquisition, image processing, and power supply can be integrated into a portable unit. A CMOS camera whose dynamic range covers more than 100 dB takes pictures of the scenery. Its image sensor has a resolution of 380 x 300 pixel. In order to reduce fixed pattern noise correlated double sampling is implemented on-chip. In addition, this sensor stands out for low power consumption, random pixel access, and local brightness adaptation. An analog-digital-converter allows direct coupling to an external signal processor or a monolithically integrated unit for image processing to compress data.

Wireless power and data transmission system for a micro implantable intraocular vision aid.

Wireless power and data transmission system developed for an intraocular vision aid for blind patients will be described. This system is applicable for patients suffering from bilateral corneal opacification but with intact posterior ocular. The system consists of an external unit as well as an implant. The external unit is required for image acquisition, channel coding, IR data transmission, and RF power transmission to the implant. The implantable unit contains a CMOS receiver, a receiver antenna coil, and the microdisplay based on a LED array. The CMOS receiver serves for reception and decoding of image data as well as driving circuits for the miniaturized LED array. In this case, mechanical wiring between the external unit and the implant is neither useful nor comfortable. An optimal technical solution needs a wireless data transfer. If the power is transferred to the implant wireless, too, the solution grows ideal. The system described in this communication employs wireless power and data transmission using an 13.56 MHz RF link for power transmission and an near IR (NIR) optical link for data transmission from an external CMOS camera and telemetry unit to the implantable micro display.

Stereoselective and endothelium-independent action of nicardipine on the isolated porcine coronary artery.

The qualitative and quantitative effects of the (+)-S and (-)-R enantiomers and of the racemic mixture of the Ca2+ channel antagonist, nicardipine, were compared on the isolated porcine coronary artery with intact and removed endothelium. All three forms of nicardipine inhibited the contractions induced by KCl (5-90 mM) in both vessel preparations. The potency (IC50) of the (+)-S and (-)-R enantiomers and of the racemic mixture was 6.6, 31.8 and 10.9 nM in the vessel with endothelium and 6.4, 41.9 and 9.8 nM in the vessel without endothelium. The parameters of the concentration-response curves for each form of nicardipine at a submaximal KCl (60 mM) concentration and the potency ratios between the two enantiomers ((+)-S/(-)-R) were not statistically significantly different (P>0.05) in the two vessel preparations. In conclusion, qualitatively, all three forms of nicardipine showed only Ca2+ channel antagonistic effects in both vessel preparations. Quantitatively, the inhibition of contraction was stereoselective, the (+)-S enantiomer being the most potent, and was endothelium-independent.

Loss of endothelium mediated vascular relaxation as a response to various clamping pressure. Part I. A pharmacological study.

BACKGROUND: The contraction/relaxation response of thoracic aortal rings clamped with two clamping pressures to KCl, noradrenaline and carbachol was studied. METHODS: Clamp A had the tip pressure PA = 0.60 N/mm2 and clamp B PB = 5.16 N/mm2. In fifteen Wistar albino rats, weighing 328 +/- 19 g (mean +/- SD) the thoracic aorta was occluded for 15 minutes and then three vascular rings (2 mm wide) were excised. The proximal unclamped ring served as a control. From distal rings the diameter of the aorta was calculated from their circumference 1.61 +/- 0.01 mm (n = 15, dmin = 1.51 mm, dmax = 1.70 mm). The rings were challenged with cumulative additions of KCl (10-80 mmol/l) to measure the contraction. Then cumulative relaxation to carbachol (0.01-100 mumol/l) as a response to noradrenaline precontraction (0.1 mumol/l) was determined. RESULTS: A significant loss (p < 0.05) of vascular relaxation in all clamped rings (clamped with PA and PB clamping pressures) was seen. No significant differences (p > 0.05) were observed for contraction between clamped and control rings clamped with clamp A, however the rings clamped with clamp B showed a significant reduction in contraction (p < 0.05). No significant differences were seen from control rings between groups A and B (p > 0.05), or from clamped rings between groups A and B (p > 0.05) for both the contraction and relaxation part of experiments. CONCLUSIONS: Endothelial vascular layers are much more susceptible to pressure injuries than was previously believed.

Loss of endothelium-mediated vascular relaxation as a response to various clamping pressures.

The contraction/relaxation responses of thoracic aortal rings clamped with two clamping pressures to potassium chloride (KC1), noradrenaline and carbachol were studied using a scanning electron microscope (SEM) to ascertain endothelial lacerations. Clamp A had the tip pressure PA = 0.60 N/mm2 and clamp B PB = 5.16 N/mm2. In 15 Wistar albino rats, weighing 328 +/- 19 g (mean +/- SD), the thoracic aorta was occluded for 15 min and then three vascular rings (2 mm wide) were excised. The proximal unclamped ring served as a control. The aorta diameter was calculated from the circumference of distal rings 1.61 +/- 0.01 mm (n = 15, dmin = 1.51 mm, dmax = 1.70 mm). The rings were challenged with cumulative additions of KC1 (10-80 mmol/l) to measure the contraction. Then cumulative relaxation on the administration of carbachol (0.01-100 mumol/l) as a response to noradrenaline precontraction (0.1 mumol/l) was determined. A significant loss (P < 0.05) of vascular relaxation in all clamped rings (clamped with PA and PB clamping pressures) was seen. No significant differences (P > 0.05) were observed for contraction between clamped and control rings clamped with clamp A, however the rings clamped with clamp B showed significantly reduction of contraction (P < 0.05). No significant differences were seen from control rings between groups A and B (P > 0.05), as well as from clamped rings between groups A and B (P > 0.05) for both the contraction and relaxation parts of the experiments. With SEM, great endothelial lacerations with complete disruption of the endothelial layer in the rings clamped with the clamp B were seen, but no disruption in rings clamped with clamp A. Therefore endothelial vascular layers are much more susceptible to pressure injuries than was previously believed. The clamped vessel wall injuries, particularly in endothelial layers, depend on the momentary peak clamping pressure (MPCP) as well as on the lower stationary clamping pressure (SCP).

Pharmacological studies with two new ergoline derivatives, the potential antipsychotics LEK-8829 and LEK-8841.

The pharmacological properties of 9,10-didehydro-N-methyl-N-(2-propynyl)-6-methyl-8 beta-aminomethylergoline (LEK-8829) and 9,10-didehydro-N-methyl-N-(2-propynyl)-2-bromo-6-methylergoline -8-beta-carboxamide (LEK-8841), new ergoline derivatives, were compared with those of haloperidol and clozapine by in vitro radioligand displacement assays, various behavioral tests and blood pressure measurements. Both ergolines displayed low affinity for rat striatal 3H-SCH23390 (7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzaze pin e)- labeled dopamine (D)1 binding sites and high affinity for striatal 3H-spiperone-labeled D2 and cortical 3H-ketanserin-labeled serotonin-2 (5-HT2) sites. The ratio of pKi values 5-HT2/D2 was 1.11 for LEK-8829 (close to that of clozapine, 1.13) and 0.98 for LEK-8841 (close to that of haloperidol, 0.95). All compounds inhibited apomorphine-induced locomotor activity in rats, apomorphine-induced climbing behavior in mice and 5-hydroxytryptophan-induced head twitches in mice and induced catalepsy in rats and in mice. LEK-8829 and clozapine, but not LEK-8841 and haloperidol, showed a certain degree of mesolimbic selectivity, i.e., they caused more potent inhibition of apomorphine-induced locomotion compared with the induction of catalepsy in rats. In the case of LEK-8829, nonspecific effects that presumably predict a side effect profile, such as potentiation of pentobarbital-induced anesthesia in mice (sedation), antagonism of oxotremorine-induced tremors in mice (anticholinergic activity), spontaneous locomotor activity in mice and norepinephrine-induced lethality in rats (sedation and hypotension), were relatively weak compared with the activities described earlier. In contrast, LEK-8841 showed nonspecific effects at the similar dose levels as dopamine and 5-HT antagonistic effects. The results of direct measurements of the influences of both compounds on blood pressure agreed with the previously mentioned findings, i.e., LEK-8829 was relatively less hypotensive than LEK-8841 was. It is suggested that LEK-8829 might be an efficient antipsychotic with a reduced propensity to cause sedative, anticholinergic and hypotensive side effects. A certain degree of mesolimbic selectivity also points toward the possibility of a reduced propensity to cause extrapyramidal symptoms. In contrast, in regard to side effects (including extrapyramidal symptoms), the profile of LEK-8841 is less promising.

Behavioral studies on LEK-8804, a new ergoline derivative with potent 5-HT1A receptor agonist and 5-HT2 receptor antagonist activity.

The 5-HT1A receptor-mediated tail flick response in rats and the 5-HT2 receptor-mediated head twitch response in mice were used to study the functional activity of a new ergoline derivative, 9,10-didehydro-N-(2-propynyl)-6-methylergoline-8 beta-carboxamide (LEK-8804). LEK-8804 dose-dependently elicited spontaneous tail flicks in rats, indicating a full 5-hydroxytryptamine1A (5-HT1A) agonist activity. This effect was very similar to that produced by the selective 5-HT1A agonist 8-OH-DPAT, both in terms of potency and time-effect relationship, and was blocked by the selective 5-HT1A antagonist NAN-190. In contrast, LEK-8804 by itself failed to produce head twitches in mice but dose-dependently inhibited the 5-hydroxytryptophan (5-HTP)-induced behavior. The inhibitory effect of LEK-8804 upon 5-HTP-induced head twitches was not attenuated by the selective 5-HT1A antagonist NAN-190. This indicates that probably not the agonist action on 5-HT1A receptors but instead the antagonism on 5-HT2 receptors was involved in the inhibition of head twitch response. It is suggested that LEK-8804 is a potent full 5-HT1A receptor agonist with possible 5-HT2 receptor antagonist properties.

Structure-activity study of some newly synthesized ergoline derivatives on 5-HT2 receptors and alpha-adrenoceptors in rabbit isolated aorta.

In a structure-activity study, carried out in rabbit isolated aorta, the effect of different structural modifications in the ergoline nucleus upon the activity at 5-HT2 receptors and alpha-adrenoceptors was determined. 9,10-didehydro-N-methyl-N-(2-propynyl)-6-methylergoline-8 beta-carboxamide (LEK 8842) was chosen as the basic backbone of this study. The parent compound LEK 8842 showed strong alpha-adrenoceptor agonistic activity and partial 5-HT2 receptor agonistic activity, and its potency (pD2 = 6.41) was comparable with that of 5-hydroxytryptamine (5-HT, pD2 = 6.84) and noradrenaline (pD2 = 6.82). Hydrogenation of the double bond in the position 9,10 (LEK 8822) attenuated the potency (pD2 = 5.35) as well as the intrinsic activity on alpha-adrenoceptors and eliminated 5-HT2 receptor agonistic activity. LEK 8822 acted on the alpha-adrenoceptors not only as a partial agonist but also as a competitive antagonist of responses elicited by noradrenaline. When tested against 5-HT, LEK 8822 acted as an antagonist. Bromination in position 2 yielded the derivative LEK 8841 with no agonistic activity at concentrations up to 3 mumol/l, yet the affinity for 5-HT2 receptors and alpha-adrenoceptors was preserved. LEK 8841 was the only one that acted as pure simple competitive antagonist of responses elicited by 5-HT (pA2 = 7.93) and noradrenaline (pA2 = 6.45). Its activity was qualitatively similar to that observed with the 5-HT2/alpha-adrenoceptor antagonist ketanserin which was tested for comparison. Concerning selectivity for 5-HT2 receptors versus alpha-adrenoceptors, LEK 8841 proved to be more selective for 5-HT2 receptors than ketanserin. pA2 values for ketanserin antagonistic activity to 5-HT and to noradrenaline were 8.22 and 7.48, respectively. Finally, quaternization in the N(6) position (LEK 8827) almost completely eliminated affinity for 5-HT2 receptors and for alpha-adrenoceptors. This study has shown that relatively small modifications in the structure of the ergoline system led to pronounced changes in the affinity as well as intrinsic activity at both receptors studied.

[Complicated course of a compression syndrome of the popliteal artery in a 36-year-old patient]. / Komplizierter Verlauf eines Kompressionssyndromes der Arteria poplitea bei einem 36jährigen Patienten.

The popliteal entrapment syndrome is an entity increasingly reported over the past few years. Anatomical variations should be considered if a localized stenosis or occlusion of the popliteal artery is diagnosed in a young, otherwise healthy individual. This case report documents a complicated course of the disease in a young man in whom diagnosis was made only after futile attempts of intraarterial lysis and dilatation at the time of a second operation. A complex crural reconstruction was necessary in order to revascularize the treatment limb.

Aspiration cytology, immunocytochemistry and electron microscopy of a malignant peripheral neuroectodermal tumor. A case report.

The findings of fine needle aspiration (FNA) cytology, immunocytochemical staining and electron microscopy (EM) in a case of malignant peripheral neuroectodermal tumor (PNET) presenting as a soft tissue mass in the lateral abdominal wall are reported. The immediate evaluation of the aspirate revealed cells of a small round cell malignant tumor. To provide a specific preoperative diagnosis, additional cytologic material was aspirated for immunocytochemical and ultrastructural investigations. While the results of EM were nonspecific, allowing only the exclusion of other small round cell malignancies, immunocytochemical staining of the aspirate was suggestive of a PNET. The diagnosis of PNET was corroborated by histopathologic and immunohistochemical findings. This case indicates that an exact preoperative categorization of small round cell malignant tumors can be made by FNA biopsy in otherwise equivocal cases when immunocytochemical and ultrastructural techniques are also utilized.

Systolic and diastolic interaction in the assessment of left ventricular function following surgical cardioplegia.

Using regionally implanted sonomicrometry crystals, we have evaluated a new index of regional function (normalised systolic shortening [NSS]) which integrates the systolic and diastolic properties of the left ventricle. Eight dogs (group I) were subjected to standard cardiopulmonary bypass and 45 min of hypothermic (10 degrees C), hyperkalaemic (25 mEq) crystalloid cardioplegia. Seven dogs (group II) underwent occlusion of the left anterior descending (LAD) coronary artery 5 min prior to initiation of cardiac arrest. The occlusion was released after 20 min, before the second cardioplegia infusion. Sarnoff left ventricular (LV) function curves were performed pre-arrest and 20, 40 and 60 min after removal of the cross-clamp. Regional assessment of myocardial function showed 55% +/- 3%, 70% +/- 3% and 70% +/- 5% recovery in the LAD region and 52% +/- 2%, 83% +/- 3% and 88% +/- 4% recovery in the circumflex (Cx) region of group I. In group II the LAD region recovered 27% +/- 1%, 31% +/- 3% and 38% +/- 3% and the Cx region showed 61% +/- 3%, 55% +/- 1% and 65% +/- 5% recovery. Comparison of the new index of ventricular function to standard indices of regional and global function demonstrate that the latter underestimate the degree of myocardial dysfunction after cardioplegic arrest, particularly in situations of acute regional myocardial ischaemia and uneven myocardial protection. The utilization of this index should provide a better standard for the more accurate assessment of interventions designed to decrease myocardial injury during cardioplegic arrest.

Medullary thyroid carcinomas express chromogranin A and a novel neuroendocrine protein recognized by monoclonal antibody HISL-19.

PURPOSE AND METHODS: A number of endocrine peptides and proteins are expressed by medullary thyroid carcinoma (MTC). The expression of two newly appreciated neuroendocrine tumor markers, chromogranin A (CgA) and the endocrine antigen defined by monoclonal antibody HISL-19, was determined in 14 MTCs by immunohistology to evaluate the clinical utility of these markers in the diagnosis of MTC. Papillary, follicular, and undifferentiated thyroid tumors were also evaluated along with an MTC cell line. The same tissues were evaluated with antibodies to human calcitonin. RESULTS: All human calcitonin antibodies were found to react with the MTCs. In addition, all MTCs were reactive for CgA and the antigen detected by antibody HISL-19. CgA was generally present in the human calcitonin-containing cells, whereas the HISL-19 antigen had a more distinctive distribution. The other thyroid tumors failed to show reactivity with any of the three antibodies. CONCLUSION: Our results demonstrate that, in addition to human calcitonin, MTCs commonly express CgA and the antigen defined by antibody HISL-19. Our observations thus add to the repertoire of endocrine substances produced by MTC. These studies also demonstrate the clinical value of immunohistologic procedures for two novel antigens in distinguishing MTCs from other thyroid tumors.

Immunochemical characterization of a novel secretory protein (defined by monoclonal antibody HISL-19) of peptide hormone producing cells which is distinct from chromogranin A, B, and C.

In this study we have investigated the biochemical properties as well as the subcellular localization of a 67 kD (35/32 kD dimer) polypeptide detected by a monoclonal antibody (HISL-19), which was generated after immunization of BALB/c mice with human islet cell preparations. This protein is expressed by neuronal and peptide hormone producing cells and shares many biochemical and molecular key features with the chromogranin proteins. As demonstrated by one-dimensional and two-dimensional gel electrophoresis, immunoblotting, monoclonal antibody HISL-19 immunoaffinity chromatography, and immunoelectron microscopy, it is a water-soluble, acidic protein stored within secretory granules of peptide hormone-producing cells, and it is released in detectable amounts into the serum of patients bearing neuroendocrine carcinomas. Differences of the HISL-19 protein and chromogranins A, B, and C are indicated by their different tissue distribution, the discrepancy of their apparent molecular weights in sodium dodecyl sulfate gels and isoelectric points, and by the lack of cross-reactivity of their specific antibodies. The protein detected by monoclonal antibody HISL-19 represents therefore a novel component of the soluble compartments of neurosecretory granules, which is distinct from chromogranin A, B, and C.

The histopathologic identification of CMV infected cells in biopsies of human renal allografts. An evaluation of 100 transplant biopsies by in situ hybridization.

In order to determine the incidence and significance of CMV infected cells within human renal allograft biopsies 100 transplant biopsies were examined for the presence of CMV DNA within the renal tissue specimens using the in situ hybridization technique. In 41 cases CMV infected cells were predominantly found within proximal tubular epithelial cells, although typical nuclear inclusion ("owl eyes") were absent. In only one case was CMV detected within a few glomerular cells. The presence of CMV infected cells within allograft biopsies does not correlate with active CMV infection of the patients at the time of biopsy. There are no significant differences in the distribution of primary and secondary CMV infections between patients with positive and negative biopsy findings. No significant differences as to the histological alterations between CMV infected and non-infected biopsies could be found. The data give evidence that the renal allograft is more often affected by CMV than is generally appreciated. The in situ hybridization technique may be useful for the fast detection of latently CMV infected cells in renal transplants and thus may influence the choice of therapeutic steps early after transplantation. Furthermore, it may facilitate the diagnosis of interstitial nephritis due to virus infection if typical nuclear inclusions in routinely stained tissue sections are absent.

Monoclonal antibody HISL-19 as an immunocytochemical probe for neuroendocrine differentiation. Its application in diagnostic pathology.

The monoclonal islet cell antibody HISL-19 was generated after immunization of BALB/c mice with human islet cell preparations. Besides reactivity with all cells of the human pancreatic islet, MAb HISL-19 also reacted with other cells of the diffuse neuroendocrine system, including anterior pituitary cells, C cells of the thyroid, endocrine cells of the gut and bronchus, the adrenal medulla, and central and peripheral neurons. In this study the authors screened a series of 53 neuroendocrine and 71 nonneuroendocrine tumors for their reactivity with MAb HISL-19 using an indirect immunoperoxidase technique on formalin-fixed and Paraplast-embedded sections. MAb HISL-19 reacted strongly with all insulomas (10), carcinoids (8), C-cell carcinomas of the thyroid (8), pituitary adenomas (6), neuroendocrine carcinomas of the skin (4), paragangliomas of the carotid body (3), and pheochromocytomas (2) tested. Neuroblastomas (3), oat-cell carcinomas of the lung (2), and melanomas (4) exhibited only very few immunoreactive cells scattered throughout the tumor or remained unstained with MAb HISL-19. With the exception of one lobular carcinoma of the breast (1/3), one adenocarcinoma of the endometrium (1/4), and one adenocarcinoma of the stomach (1/6), nonneuroendocrine tumors were negative with MAb HISL-19. Biochemical findings obtained by SDS-PAGE, "Western" immunoblotting, immunoaffinity chromatography, and absorption experiments indicate that the MAb HISL-19-defined antigen is not related to neuron specific enolase. Because the epitope recognized by MAb HISL-19 is well preserved in formalin-fixed and routinely processed tissues, this monoclonal antibody finds potential applications in diagnostic pathology as an indicator for neuroendocrine cells and their neoplasms.