An integrated software solution for multi-modal mapping of morphological and functional ocular data

Various morphological and functional techniques for retina examination have been established in the recent years. Although many examination results are spatially resolved and can be mapped onto data originating from other modalities, usually only data from one modality is analyzed by a clinician at a time. This is mainly because there is no software available to the public that enables the registration of structure and function in the clinical setting. Therefore we developed an integrated mapping application that allows the registration and analysis of morphological data (fundus photography, optical coherence tomography, scanning laser ophthalmoscopy images, and GDx thickness profiles) and functional data (multifocal electroretinography, multifocal pattern electroretinography, perimetry, and microperimetry). To obtain quantitative data that can be used for clinical trials and statistical analyses, extraction routines for morphological parameters - such as retinal layer thicknesses and measures of the vascular network - have been integrated. Global, regional and point-specific data from registered modalities can be extracted and exported for statistical analyses. In this article we present the implementation and examples of use of the developed software.

An integrated domain specific language for post-processing and visualizing electrophysiological signals in Java

Electrophysiology of vision - especially the electroretinogram (ERG) - is used as a non-invasive way for functional testing of the visual system. The ERG is a combined electrical response generated by neural and non-neuronal cells in the retina in response to light stimulation. This response can be recorded and used for diagnosis of numerous disorders. For both clinical practice and clinical trials it is important to process those signals in an accurate and fast way and to provide the results as structured, consistent reports. Therefore, we developed a freely available and open-source framework in Java (http://www.eye.uni-tuebingen.de/project/idsI4sigproc). The framework is focused on an easy integration with existing applications. By leveraging well-established software patterns like pipes-and-filters and fluent interfaces as well as by designing the application programming interfaces (API) as an integrated domain specific language (DSL) the overall framework provides a smooth learning curve. Additionally, it already contains several processing methods and visualization features and can be extended easily by implementing the provided interfaces. In this way, not only can new processing methods be added but the framework can also be adopted for other areas of signal processing. This article describes in detail the structure and implementation of the framework and demonstrate its application through the software package used in clinical practice and clinical trials at the University Eye Hospital Tuebingen one of the largest departments in the field of visual electrophysiology in Europe.

Multimodal multidimensional imaging for visual system status assessment

Non-invasive optical methods that enable in vivo or in situ visualization of tissue components are of particular relevance in ophthalmology, as they can provide key information about the relationship between the structure and function of the visual system. In this paper we present a semiautomated multimodal imaging tool for co-registration of images of retinal structure and its function, based on point correspondence. Decision support analysis was applied to define significant features for the multimodal mapping system, using a set of 1500 subjects who were affected by blindness associated hereditary retinal dystrophies. Additionally, the developed software was tested by two experienced observers using data from 25 subjects. Inter-observer and intra-observer reliability was determined. We conclude that semi-automated multimodal mapping could be a promising new tool for an individualized visual system status assessment that can be applied for the early diagnosis of blindness associated diseases. Moreover, this mapping approach should prove particularly appropriate for studying pathophysiology in inherited blindness associated diseases.

Extraocular surgery for implantation of an active subretinal visual prosthesis with external connections: feasibility and outcome in seven patients

BACKGROUND

Due to low energy levels in microphotodiode-based subretinal visual prostheses, an external power supply is mandatory. We report on the surgical feasibility and the functional outcome of the extraocular part of an approach to connect a subretinal prosthesis to an extracorporeal connector in the retro-auricular space via a trans-scleral, transchoroidal cable.

METHODS

Seven volunteers with retinitis pigmentosa received an active subretinal implant; energy was supplied by gold wires on a trans-sclerally, transchoroidally implanted polyimide foil leading to the lateral orbital rim where it was fixated and connected to a silicone cable. The cable was implanted subperiostally beneath the temporal muscle using a trocar to the retro-auricular space where it penetrated the skin for connection to a stimulator. To avoid subretinal movement of the implant, three tension relief points have been introduced.

RESULTS

All implantations were performed as planned without complications, and no serious adverse events occurred in the postoperative period. Fixation of the implants was stable throughout the entire study duration of 4 weeks; permanent skin penetration proved to be uncomplicated. Motility was minimally restricted in downgaze and ab-/adduction. Explantation was uneventful.

CONCLUSION

The above-described procedure provides a method for stable fixation of a subretinal device with a trans-scleral, transchoroidal cable connection to an extracorporeal connector.

Multiple internal reflection poly(dimethylsiloxane) systems for optical sensing

Compact poly(dimethylsiloxane)-based (PDMS) multiple internal reflection systems which comprise self-alignment systems, lenses, microfluidic channels and mirrors have been developed for highly sensitive absorbance measurements. With the proper definition of air mirrors at both sides of the sensing region, the optical path of the light from the LED has been meaningfully lengthened without a dramatic increase of the mean flow cell volume. By recursive positioning of such air mirrors, propagating multiple internal reflection (PMIR) systems have been designed, simulated and characterized. Experimental results confirm the ray-tracing predictions and allow the determining that there are some regions of the mean flow cell volume that do not contribute to the increase of the sensitivity. The tailoring of the sensing region, following the optical path, results in a similar limit of detection (110 nM) for fluorescein diluted in phosphate buffer. Finally, a ring configuration, labelled RMIR, has also been developed. With the addition of a third air mirror, the LOD can be decreased to 41 nM with the additional advantage of a substantial decrease of the length of the sensing region. These results confirm the validity of the proposed systems for high sensitivity measurements.

[Chronic mesenteric ischemia with consecutive ischemic colitis. Suggestions for diagnosis and therapy]

The incidence of acute mesenteric ischaemia has decreased over the last few years. However, cases of chronic mesenteric ischaemia have grown in number, as this disease is the most frequent disorder of the large intestine in the elderly. The typical clinical presentation of ischaemic colitis develops gradually and only becomes recognisable in the late stage of the disease. We present a 51-year-old woman with a history of unexplained abdominal pain. Multislice CT demonstrated an irregular stenosis of the truncus coeliacus and superior mesenteric artery. A Riolan's anastomosis was present and showed excellent perfusion. After a hemicolectomy 6 years previously, different radiologic procedures and endoscopy revealed a structural tumour at the colon transversum we suspected to be malignant. A sequential procedure was conducted. In a first vascular intervention, the truncus coeliacus was reconstructed with a vein patch, and the mesenteric superior artery was replanted. The second laparotomy was performed for revision of the superior mesenteric artery and resection of the intestinal tumour. However, no carcinoma was found in histological examination. In fact, the individual multidisciplinary considerations play an important role in determining the best treatment strategy, if intervention is warranted. Based on our experience, sequential intervention with a common clinical pathway is the safest and most suitable and economic procedure for curing complex pathologies.

A capillary electrophoresis chip with hydrodynamic sample injection for measurements from a continuous sample flow

A microchip-based capillary electrophoresis device supported by a microfluidic network made of poly(dimethylsiloxane), used for measuring target analytes from a continuous sample flow, is presented. The microsystem was fabricated by means of replica molding in combination with standard microfabrication technologies, resulting in microfluidic components and an electrochemical detector. A new hydrodynamic sample injection procedure is introduced, and the maximum number of consecutive measurements that can be made with a poly(dimethylsiloxane) capillary electrophoresis chip with amperometric detection is investigated with respect to reproducibility. The device features a high degree of functional integration, so the benefits associated with miniaturized analysis systems apply to it.

Optimization of poly(dimethylsiloxane) hollow prisms for optical sensing

A new generation of simple, robust and compact microfluidic systems with optical readout is presented. The devices consist of hollow prisms fabricated by soft-lithography, together with microlenses and self-aligned channels for fibre optic positioning, conferring the system with a high degree of monolithic integration. Its working principle is based on the absorption of the working wavelength (lambda = 460 nm) by the different substances that can fill the hollow prisms. By modifying the volumes and geometries, optimization of the presented systems has been achieved. Results show how the limit of detection (LOD) for fluorescein and methylorange diluted in phosphate buffer can be significantly lowered, by increasing the size of the prism or increasing the total deviation angle. For our investigations we used concentrations for which the Beer-Lambert law is fulfilled and the measurements showed a LOD in the microM range for both species. Finally, since the change in the fractions of the methylorange as a function of the pH causes a variation of the total absorption of the solution, the hollow prisms have also been used for pH measurements.

Absence of intrinsic electric conductivity in single dsDNA molecules

The intrinsic dc conductivity of long, individual lambda phage dsDNA molecules has been investigated by ultrasensitive low current-voltage-spectroscopy (IV) under ambient conditions and controlled low humidity inert gas atmosphere on microfabricated metal-insulator-metal gap structures. We found a strong dependence of the measured conductivity on the apparent humidity, which we attribute to capillary condensation of water to the immobilized DNA molecules, giving rise to additional ionic currents. Additional IV-spectroscopy experiments under controlled argon atmosphere always revealed a significant drop in electrical conductivity to 4 x 10(-15)AV(-1)microm(-1), indicating almost no considerable contribution of electrical long range charge transport.

[Acetabular shape and cementless cups. Comparison of osteoarthritic hips and implant design]

The anatomy of the hip must be taken into account in order to ensure primary stability of cementless acetabular implants. In this study we analyzed the shapes of osteoarthritic acetabula and compared these to normal non-degenerative acetabula and to pressfit implants. We measured 92 acetabula with osteoarthritic deformations and 35 non-degenerative acetabula. Bone tissue samples from 50 osteoarthritic acetabula were microradiographically analyzed. Furthermore, the size of the entrance plane of 37 pressfit cups was determined. The craniocaudal and ventrodorsal diameters of osteoarthritic acetabula correlate strongly ( r=0.87). In craniocaudal direction, the acetabular diameter correlates significantly to both the radius of the lunate surface ( r=0.42) and the acetabular base ( r=0.54). Osteoarthritic acetabula have a deeper shape as degeneration increases and the entrance plane becomes significantly more circular ( p<0.05). When comparing osteoarthritic and non-arthrotic acetabula, the following values differ significantly (p<0.05): craniocaudal radius of the acetabular base, craniocaudal and ventrodorsal radius of the lunate surface, and ventrodorsal divergence between lunate surface and acetabular base. To reconstruct an acetabular offset which concurs with central points of the femoral head and the radius of the lunate surface, the level of the insert's entrance plane must be outside the entrance planes of the cup and acetabulum. The rims of hemispheric cups need to be trimmed to prevent these cups from extending beyond the acetabular rim.

Poly(dimethylsiloxane) hollow Abbe prism with microlenses for detection based on absorption and refractive index shift

In this paper we report on an optical detection method that utilizes two physical effects for signal transduction, namely absorption and shift of refractive index. The device consists of a hollow prism and was fabricated by means of soft-lithography. It exhibits a high degree of monolithic integration. In order to keep down the amount of external equipment that is necessary to run the device, we were able to integrate several functions, such as focussing of light and alignment of optical fibres. Since all components are fabricated in the same material and in the same process, compatibility with other microfluidic devices or components can be achieved easily. The functional efficiency and the performance of the detector were tested by investigating solutions containing fluorescein, with concentrations between 5 and 1000 microM. The results clearly show the two regions in which the two physical effects are effective.

[Current diagnosis and therapy of non-occlusive mesenteric ischemia]

PURPOSE

Non-occlusive mesenteric ischemia (NOMI) is a life threatening disease. Therapy and prognosis depend upon the length of time elapsed between primary clinical manifestation and the time of definitive diagnosis and treatment.

MATERIALS AND METHODS

NOMI was diagnosed by intraarterial selective angiography in four patients. After a bolus administration of 20 g Alprostadil (Prostavasin) into the superior mesenteric artery, intraarterial perfusion was continued with 60 microg Alprostadil/day via the catheter for three days.

RESULTS

The mesenteric ischemia resolved in all patients. One patient recovered completely. Three patients recovered from mesenteric ischemia, but died subsequently due to complications of their primary diseases.

CONCLUSION

When NOMI without perforation or necrosis of the bowel wall is suspected clinically, immediate intraarterial angiography is the diagnostic method of choice. If NOMI is confirmed, the appropriate treatment is the intraarterial application of potent vasodilators for several days. The diagnostic work-up in suspected NOMI and the impact of different radiological examinations are explained. The literature is reviewed.

Comparison of COBE Spectra software version 4.7 PBSC and version 6.0 auto PBSC program

Until recently, the collection of peripheral blood progenitor cells (PBPC) has been semi-automated by using the COBE Spectra, with the operator manually maintaining the position of the white cells being collected. The COBE Spectra Version 6.0 apheresis device offers the user an automated program for the collection of PBPC. In this study, we compared the new software Version 6.0 to that of Version 4.7. Patients (n = 46) undergoing PBPC collection were allocated to cell processing with either Version 4.7 (n = 24) or Version 6.0 (n = 22). The CD34+ cell count, mononuclear cell (MNC) count, white cell count (WCC), hemoglobin (Hb), and platelet content in the autograft product by using the two versions were compared. We divided the analysis into three subsets according to peripheral blood (PB) CD34 content: <10x10(6)/L, 10-50x10(6)/L and >50x10(6)/L. Analysis of the three subsets showed no statistical difference between results obtained when the starting PB CD34+ cell count was 10-50x10(6)/L (P=0.08) or >50x10(6)/L (P=0.4065). At lower starting PB CD34+ cell counts of <10x10(6)/L, Version 4.7 was superior (P=0.0167). However, autograft platelet contamination of the autograft was significantly higher using Version 4.7 (P=<0.0001).

[The optimization of MR cholangiopancreatography]

PURPOSE

To improve the image quality of magnetic resonance cholangiopancreatography (MRCP) by modification of examination conditions.

MATERIALS AND METHODS

MRCP of 72 patients was performed with a 1.5 T system (Magnetom Vision, Siemens, 25 mT/m) using two breath-hold techniques, half-fourier acquisition with multislice T2-WI HASTE in MIP technique, and single shot T2-WI turbo-spin-echo (RARE) with different slice thicknesses. The effects of n-butylscopolamine were assessed. Furthermore, oral contrast agents [barium sulfate, Fe(II)-gluconate, Fe(II,III)-oxide] in various concentrations were used. The slice thickness was varied for the RARE sequence (3-7 cm).

RESULTS

N-butylscopolamine had no influence on image quality. Improvements could be attained by variation of the slice thickness. A significant reduction of disturbing background noise was obtained by oral application of iron gluconate, or iron oxide-containing contrast media. Similar improvements were achieved with barium sulfate.

CONCLUSIONS

Variation of slice thickness allows an improvement of MRCP quality. Oral contrast media improve the image quality of MRCP. The expense of contrast media may be a determinant of choice.

Modulation of NMDA effects on agonist-stimulated phosphoinositide turnover by memantine in neonatal rat cerebral cortex

1. The ability of memantine (1-amino-3,5-dimethyladamantane) to antagonize the modulatory effects of N-methyl-D-aspartate (NMDA) on phosphoinositide turnover stimulated by muscarinic cholinoceptor- and metabotropic glutamate receptor-agonists has been examined in neonatal rat cerebral cortex slices. 2. Memantine antagonized the inhibitory effect of NMDA (100 microM) on both total [3H]-inositol phosphate ([3H]-InsPx) and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) mass accumulations stimulated by carbachol (1 mM) with EC50 values of 21 and 16 microM respectively. 3. Memantine concentration-dependently antagonized (IC50 24 microM) the ability of NMDA (10 microM) to potentiate [3H]-InsPx accumulation in response to a sub-maximal concentration of the metabotropic glutamate receptor agonist, 1S,3R-ACPD (10 microM). 4. The small (approx. 3 fold), concentration-dependent increase in [3H]-InsPx accumulation stimulated by NMDA was completely antagonized by the prototypic NDMA receptor-channel blocker, MK-801 (1 microM) at all concentrations of NDMA studied (1-1000 microM). In contrast, antagonism by memantine (100 microM) was observed only at low concentrations of NMDA (1-10 microM), whilst [3H]-InsPx accumulation stimulated by high concentrations of NMDA (300-1000 microM) was markedly enhanced by memantine. 5. Assessment of the incorporation of [3H]-inositol into inositol phospholipids revealed that memantine (100 microM) caused an approximate 2 fold increase in the labelling of phosphatidylinositol, phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate. 6H.p.l.c. separation of [3H]-inositol (poly)phosphates demonstrated that whilst memantine (100 microM)alone had no significant effect on the accumulation of any isomer, it substantially altered the profile of accumulation stimulated by NMDA (1 mM), greatly facilitating accumulation of Ins(1,4,5)P3 and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4).7.These data provide evidence that memantine can antagonize the actions of NMDA in neonatal rat cerebral cortex slices in a manner consistent with this agent acting as a NMDA receptor-channel blocker. In addition, at least two further actions of memantine can be proposed. Memantine increases the rate of [3H]-inositol incorporation into the cellular inositol phospholipid fraction, without significantly stimulating phosphoinositide turnover. Furthermore, memantine can substantially alter patterns of inositol (poly)phosphates stimulated by NMDA, promoting the accumulation of the established and putative second messengers Ins(1,4,5)P3 and Ins(1,3,4,5)P4 which are not increased by NMDA in the absence of memantine. It is unknown whether these latter loci of memantine action contribute to known therapeutic actions of this agent.

Memantine-induced dopamine release in the prefrontal cortex and striatum of the rat--a pharmacokinetic microdialysis study

Memantine (1-amino-3,5-dimethyl-adamantane) has therapeutic potential in Parkinson's disease and dementia. However, its effect on dopaminergic activity in the central nervous system is still unclear. Therefore, we studied the effect of memantine on dopamine release in prefrontal cortex and striatum, using in vivo microdialysis. Memantine (5, 10 and 20 mg/kg i.p.) caused a dose-dependent increase in dopamine release up to nearly 50% over basal levels. The output of the metabolites was of later onset and longer duration in prefrontal cortex and in striatum. After administration of 10 and 20 mg/kg, in both brain areas memantine levels could be detected over the investigated period of 160 min. The maximal concentrations (Cmax) differed dose dependently, whereas the time to reach this maximum (tmax) was almost identical (68.5 +/- 3.4 min). From the flat elimination profile a half-life of 2.8 +/- 0.5 h (range 2-3.4 h) was calculated. These data demonstrate enhanced dopamine release and metabolism after memantine treatment and support the assumption of an interaction between noncompetitive NMDA-receptor antagonists and dopaminergic systems.

Glutamate antagonists have different effects on spontaneous locomotor activity in rats

Locomotor activity, ataxia, and stereotypy were assessed in the open field after administration of NMDA and AMPA antagonists acting by different mechanisms. The interaction with glutamatergic receptors was confirmed in the binding assay. (+)MK-801 and phencyclidine (PCP) produced similar changes in horizontal activity, i.e., a strong increase from the beginning of the test. Ketamine, and to a lesser extent, memantine, enhanced horizontal activity at the later observation periods only. Amantadine and NBQX produced a slight inhibition, while GYKI-52466, d-cycloserine, (+R)-HA-966, CGP-37849, and dextromethorphan were ineffective. Vertical activity (rearings) were inhibited by most agents except GYKI-52466 and gly-B partial agonists. At higher doses ataxia was seen after: MK-801, PCP, ketamine, memantine, amantadine, CGP-37849, dextromethorphan, and GYKI-52466. Hence, the inhibition of NMDA and AMPA receptors by agents acting at different recognition sites produces qualitatively different behavioral consequences.

The effect of physical training on rat calf muscle, oxygen tension, blood flow, metabolism and function in an animal model of chronic occlusive peripheral vascular disease

The effect of treadmill physical training (PT) on rat gastrocnemius/plantaris muscle after bilateral femoral artery ligation was investigated. To enable a comparison to be made between the susceptibility of muscles with restricted blood flow and normally perfused skeletal muscle to PT, animals without ligated femoral arteries also underwent PT. PT increased the oxidative capacity of the gastrocnemius/plantaris muscle, as judged by the activity of citrate synthase, and reduced muscle fatigue in both groups of animals. Exercise also tended to lower the activity of a marker enzyme for glycolysis, glyceraldehyde-phosphate dehydrogenase in all animals, although this only reached the level of statistical significance in the animals with ligated femoral arteries. In the animals with restricted muscle blood flow, PT increased gastrocnemius skeletal muscle blood flow and pO2 and prolonged the time taken to attain maximum muscle twitch tension. The results indicate a great susceptibility of hindlimb skeletal muscles of rats with ligated femoral arteries to PT. They also suggest that the beneficial effect of PT observed in man with chronic occlusive arterial disease (COAD) may result both from an increase in muscle blood flow and from an enhanced mitochondrial respiratory activity in the afflicted muscle.

The ability of denbufylline to inhibit cyclic nucleotide phosphodiesterase and its affinity for adenosine receptors and the adenosine re-uptake site

1. Denbufylline has been examined for its ability to inhibit cyclic nucleotide phosphodiesterase isoenzymes from rat cardiac ventricle and cerebrum, as well as for its affinity for adenosine A1 and A2 receptors and the re-uptake site. For comparison, SK&F 94120, theophylline and 3-isobutyl-1-methyl-xanthine (IBMX) were examined as phosphodiesterase inhibitors whilst N6-cyclohexyladenosine, R(-)-N6-(2-phenylisopropyl)-adenosine, 5'-N-ethylcarboxamido-adenosine, 2-nitrobenzylthioinosine, theophylline and IBMX were examined for their affinity for adenosine binding sites. 2. This investigation confirmed the presence of four phosphodiesterase activities in rat cardiac ventricle; in rat cerebrum only three were present. 3. Denbufylline selective inhibited one form of Ca2+-independent, low Km cyclic AMP phosphodiesterase. The form inhibited was one of two present in cardiac ventricle and the sole one in cerebrum. This form was not inhibited by cyclic GMP. The inotropic agent SK&F 94120 selectively inhibited the form of cyclic AMP phosphodiesterase which was inhibited by cyclic GMP present in cardiac ventricle. Theophylline and IBMX were relatively non-selective phosphodiesterase inhibitors. 4. Denbufylline was a less potent inhibitor of ligand binding to adenosine receptors than of cyclic AMP phosphodiesterase. This contrasted with theophylline, which had a higher affinity for adenosine receptors, and IBMX which showed no marked selectivity. Denbufylline, theophylline and IBMX all had a low affinity for the adenosine re-uptake site. 5. Denbufylline is being developed as an agent for the therapy of multi-infarct dementia. The selective inhibition of a particular low Km cyclic AMP phosphodiesterase may account for the activity of this compound.

8-phenyltheophylline as an inhibitor of cyclic AMP hydrolysis by cyclic nucleotide phosphodiesterase

1. The inhibition, by theophylline and 8-phenyltheophylline, of cAMP hydrolysis by cyclic nucleotide phosphodiesterase from rat fat cells, abdominal aorta, gastrocnemius muscle, erythrocytes and cerebrum was examined. 2. Theophylline was an approximately equieffective inhibitor of cAMP hydrolysis in all tissue extracts. In contrast, 8-phenyltheophylline was a markedly more effective inhibitor of cAMP breakdown in erythrocytes and skeletal muscle than in smooth muscle, brain and fat cells. The 8-phenyl substituted compound was a more potent inhibitor in erythrocytes and skeletal muscle than theophylline. 3. 8-phenyltheophylline has been postulated to be a very selective adenosine receptor antagonist, the present study indicates, that in some tissues 8-phenyltheophylline is not so selective as an adenosine receptor antagonist as has previously been suggested. 4. Analysis of cyclic AMP breakdown by cyclic nucleotide phosphodiesterase in fat cells and erythrocytes demonstrated the presence of high and low affinity forms. 5. Theophylline was slightly more effective as an inhibitor of the high than of the low affinity forms in both tissues. 8-phenyltheophylline was weakly effective as an inhibitor of all isoenzymes from fat cells and selectively inhibited the high affinity phosphodiesterase from erythrocytes. 6. The results suggest that 8-phenyltheophylline is a selective inhibitor of a cyclic nucleotide phosphodiesterase with a high affinity for cAMP, which has relatively greater activity in erythrocytes, and presumably in skeletal muscle, than in other tissues such as fat cells.

Tissue selective inhibition of cyclic nucleotide phosphodiesterase by denbufylline

The effects of the novel alkylxanthine denbufylline (1,3-d-n-butyl-7-(2'-oxopropyl)-xanthine), theophylline and 3-isobutyl-1-methyl-xanthine (IBMX), on the breakdown of cyclic AMP in homogenates of rat erythrocytes, abdominal aorta, adipocytes and cardiac and skeletal muscle were studied. Theophylline and IBMX inhibited cyclic nucleotide phosphodiesterase in all tissue extracts. In contrast, denbufylline was a tissue selective inhibitor of cyclic nucleotide phosphodiesterase. In skeletal muscle and erythrocytes, denbufylline (10 mumol/l) inhibited cyclic nucleotide phosphodiesterase activity by at least 80%. In these tissues, denbufylline was 10-30 and 100-300fold more potent than IBMX and theophylline, respectively. In adipocytes and cardiac and smooth muscle, denbufylline was not an effective inhibitor of cyclic AMP breakdown. Hofstee analysis of phosphodiesterase activity revealed that denbufylline selectively inhibited high affinity cyclic AMP phosphodiesterase in erythrocytes and skeletal muscle. In adipocytes, cardiac and vascular smooth muscle, denbufylline did not effectively inhibit the composite cyclic nucleotide phosphodiesterase activities either with high or with low affinity for cyclic AMP.

The effect of short-term and long-term femoral artery ligation on rat calf muscle oxygen tension, blood flow, metabolism and function

The effect of short-term (1 day-1 week) and long-term (6-12 weeks) femoral artery ligation on the oxygen tension (pO2), blood flow, metabolism and function of rat gastrocnemius muscle has been examined. Femoral artery ligation reduced resting blood flow, pO2 and pH. Concomitantly, the concentration of high energy phosphates was reduced and the muscle lactate concentration increased. The fatigue developed by the gastrocnemius/plantaris muscle, during a 10 min period of isometric exercise, was increased and the associated hyperaemia was attenuated. The surgery, performed to ligate the artery, induced an increase in the plasma fibrinogen concentration and whole blood viscosity. As the time interval increased after the femoral artery ligation there was a progressive reduction of the magnitude of the effects. Ten weeks after ligation resting muscle concentrations of high energy phosphates and lactate, whole blood viscosity and muscle pH had normalized. However, resting muscle blood flow, pO2, ability to sustained isometric exercise and the exercise induced hyperaemia were still reduced compared to intact animals. Comparison with literature data reveals that the changes produced by chronic femoral artery ligation in rat calf muscle mimic those seen in man with intermittent claudication.

Inner medullary osmolality and sodium concentration are decreased in rats during escape from DOCA-induced salt retention

1. Papillary osmolality and sodium and potassium concentrations were determined in rats during a control period and during escape from the sodium-retaining effect of deoxycorticosterone acetate and compared with the changes observed after acute frusemide injection. 2. During escape, papillary osmolality [554 +/- 36 vs 754 +/- 42 mmol/kg of papillary water (H2O), P less than 0.005] and papillary sodium concentration (131 +/- 7 vs 182 +/- 8 mmol/kg H2O, P less than 0.001) were significantly decreased as compared with the control values, while papillary potassium concentration remained unchanged. 3. Frusemide decreased papillary osmolality to 538 +/- 41 mmol/kg H2O (P less than 0.005), papillary sodium concentration to 125 +/- 9 mmol/kg H2O (P less than 0.001) and papillary potassium concentration from 80 +/- 2 to 69 +/- 3 mmol/kg H2O (P less than 0.05). 4. The present results suggest that medullary portions of the distal tubule (probably the ascending loop of Henle) may represent one site of tubular sodium chloride rejection during escape from the sodium-retaining effect of deoxy-corticosterone acetate.

Regulatory hyperparathyroidism in a pig breed with vitamin D dependency rickets

A radioimmunoassay for porcine parathyroid hormone has been developed and applied to measure immunoreactive parathyroid hormone (PTH) in plasma of pigs with hereditary vitamin D dependency rickets (VDDR) (pseudovitamin D deficiency rickets). Levels of 25-hydroxycholecalciferol (25-(OH)-D3) in plasma were measured by a protein binding assay. Both plasma concentrations of PTH and 25-(OH)-D3 showed an approximately 4-fold increase compared to normal pigs. PTH levels increased with duration of the disease. Daily dosing of the animals with 1--4 micrograms of 1,25-dihydroxycholecalciferol (1,25-(OH)2-D3) reduced PTH concentrations and resulted in clinical healing. Iv administration of 10 micrograms of 25-(OH)-D3/day did not alter PTH concentrations nor the clinical symptoms. The results suggest that these animals suffer from regulatory hyperparathyroidism. The metabolic defect could be due to a failure of the kidney to convert 25-(OH)-D3 to 1,25-(OH)2-D3.

[A highly sensitive C-terminal specific radioimmunoassay for human parathormone as a routine method (author's transl)]

The basis for the radioimmunoassay of parathormone (PTH) as a routine method is a new sheep antiserum and a labelled PTH stabilised by a modification of the purification technique. The antiserum is obtained by immunisation with pig and cattle parathormone, it is C-terminal specific and is used in the assay in a final dilution of 1:35000. The affinity to human PTH is markedly greater than of the antisera used up to now. Two purification steps of 125J labelled bovine PTH lead to a tracer with a nonspecific binding of approximately 5% which increases to approximately 10% within 6 weeks. All normal sera investigated so far were measurable quantitatively (normal range 0.7 to 2.5 mul/equiv.). The lower sensitivity range was at 0.3 mul/equiv. All patients with chronic renal insufficiency and dialysis patients have an increased PTH concentration (3.9 to greater than 20 mul/equiv.). This also applies to patients with primary hyperparathyroidism (2.9 to greater than 20 mul/equiv.).