Thyroxine-binding globulin: investigation of microheterogeneity

Preparations of T4-binding globulin (TBG) from human serum was performed using only two affinity chromatography steps. Purity of the protein was demonstrated by a single band in overloaded disc and sodium dodecyl sulfate electrophoresis, equimolar binding to T4, and linearity in sedimentation velocity run. The molecular weight was calculated to be 60,000 +/- 3,000 daltons (n = 3), the sedimentation coefficient was 3.95S, and the Stokes' radius was 37 A. The amino acid composition was found to be in good agreement with the calculations of other authors. By isoelectric focussing (IEF), pure TBG showed four main bands at pH 4.25, 4.35, 4.45, and 4.55 together with several fainter bands. The N- acetylneuraminic acid (NANA) content of the four TBG bands isolated by preparative IEF was found to decrease from 10.2 mol NANA/mol TBG in the band at pH 4.25 to 4.8 mol NANA/mol TBG in the band at pH 4.55. No significant difference in the affinity constants of the TBG bands to T4 was found. The affinity constants for TBG ranged from 3.1 x 10(9) to 7.2 x 10(9) M-1. Sequential kinetic desialylation of pure TBG resulted in a progressive tendency toward one major band at pH 6.0. In native sera, microheterogeneity of TBG was detected after IEF on polyacrylamide gel plates by immunofixation. The typical TBG patterns shown by pure TBG were also found in normal subjects. Characteristic deviations from this pattern were found in the sera of females during estrogen therapy or pregnancy, where there was a gradual increase in density of the band at pH 4.25 and the appearance of an additional band at pH 4.15. In sera from patients with liver disease and elevated TBG levels, there was a fading of the acidic bands, whereas the more alkaline band at pH 4.55 was intensified. It is therefore proposed that microheterogeneity of TBG is caused by differences in NANA content and that variations of TBG patterns in native sera may reflect altered TBG synthesis or degradation. A genetically related microheterogeneity of TBG could not be demonstrated after examination of 800 sera, including 2 families with quantitative TBG deficiency

Gastropod-derived haemocyte extracellular traps entrap metastrongyloid larval stages of Angiostrongylus vasorum, Aelurostrongylus abstrusus and Troglostrongylus brevior

Background: Phagocyte-derived extracellular traps (ETs) were recently demonstrated mainly in vertebrate hosts as an important effector mechanism against invading parasites. In the present study we aimed to characterize gastropod-derived invertebrate extracellular phagocyte trap (InEPT) formation in response to larval stages of important canine and feline metastrongyloid lungworms. Gastropod haemocytes were isolated from the slug species Arion lusitanicus and Limax maximus, and the snail Achatina fulica, and exposed to larval stages of Angiostrongylus vasorum, Aelurostrongylus abstrusus and Troglostrongylus brevior and investigated for gastropod-derived InEPT formation. Results: Phase contrast as well as scanning electron microscopy (SEM) analyses of lungworm larvae-exposed haemocytes revealed ET-like structures to be extruded by haemocytes thereby contacting and ensnaring the parasites. Co-localization studies of haemocyte-derived extracellular DNA with histones and myeloperoxidase in larvae-entrapping structures confirmed classical characteristics of ETs. In vivo exposure of slugs to A. vasorum larvae resulted in InEPTs being extruded from haemocytes in the slug mucous extrapallial space emphasizing the pivotal role of this effector mechanism against invasive larvae. Functional larval entrapment assays demonstrated that almost half of the haemocyte-exposed larvae were contacted or even immobilized by released InEPTs. Overall, as reported for mammalian-derived ETs, different types of InEPTs were here observed, i.e. aggregated, spread and diffused InEPTs. Conclusions: To our knowledge, this study represents the first report on metastrongyloid lungworm-triggered ETosis in gastropods thereby providing evidence of early mollusc host innate immune reactions against invading larvae. These findings will contribute to the better understanding on complex parasite-intermediate host interactions since different gastropod species bear different transmitting capacities for metastrongyloid infections

Tensile strained InxGa1−xPIn_{x}Ga_{1-x}P membranes for cavity optomechanics

We investigate the optomechanical properties of tensile-strained ternary InGaP nanomembranes grown on GaAs. This material system combines the benefits of highly strained membranes based on stoichiometric silicon nitride, with the unique properties of thin-film semiconductor single crystals, as previously demonstrated with suspended GaAs. Here we employ lattice mismatch in epitaxial growth to impart an intrinsic tensile strain to a monocrystalline thin film (approximately 30 nm thick). These structures exhibit mechanical quality factors of 2*10^6 or beyond at room temperature and 17 K for eigenfrequencies up to 1 MHz, yielding Q*f products of 2*10^12 Hz for a tensile stress of ~170 MPa. Incorporating such membranes in a high finesse Fabry-Perot cavity, we extract an upper limit to the total optical loss (including both absorption and scatter) of 40 ppm at 1064 nm and room temperature. Further reductions of the In content of this alloy will enable tensile stress levels of 1 GPa, with the potential for a significant increase in the Q*f product, assuming no deterioration in the mechanical loss at this composition and strain level. This materials system is a promising candidate for the integration of strained semiconductor membrane structures with low-loss semiconductor mirrors and for realizing stacks of membranes for enhanced optomechanical coupling.Comment: 10 pages, 3 figure

Identification of the upward movement of human CSF in vivo and its relation to the brain venous system.

CSF flux is involved in the pathophysiology of neurodegenerative diseases and cognitive impairment after traumatic brain injury, all hallmarked by the accumulation of cellular metabolic waste. Its effective disposal via various CSF routes has been demonstrated in animal models. In contrast, the CSF dynamics in humans are still poorly understood. Using novel real-time MRI, forced inspiration has been identified recently as a main driving force of CSF flow in the human brain. Exploiting technical advances toward real-time phase-contrast MRI, the current work analyzed directions, velocities, and volumes of human CSF flow within the brain aqueduct as part of the internal ventricular system and in the spinal canal during respiratory cycles. A consistent upward CSF movement toward the brain in response to forced inspiration was seen in all subjects at the aqueduct, in 11/12 subjects at thoracic level 2, and in 4/12 subjects at thoracic level 5. Concomitant analyses of CSF dynamics and cerebral venous blood flow, that is, in epidural veins at cervical level 3, uniquely demonstrated CSF and venous flow to be closely communicating cerebral fluid systems in which inspiration-induced downward flow of venous blood due to reduced intrathoracic pressure is counterbalanced by an upward movement of CSF. The results extend our understanding of human CSF flux and open important clinical implications, including concepts for drug delivery and new classifications and therapeutic options for various forms of hydrocephalus and idiopathic intracranial hypertension

Inspiration is the major regulator of human CSF flow.

The mechanisms behind CSF flow in humans are still not fully known. CSF circulates from its primary production sites at the choroid plexus through the brain ventricles to reach the outer surface of the brain in the subarachnoid spaces from where it drains into venous bloodstream and cervical lymphatics. According to a recent concept of brain fluid transport, established in rodents, CSF from the brain surface also enters the brain tissue along para-arterial routes and exits through paravenous spaces again into subarachnoid compartments. This unidirectional flow is mainly driven by arterial pulsation. To investigate how CSF flow is regulated in humans, we applied a novel real-time magnetic resonance imaging technique at high spatial (0.75 mm) and temporal (50 ms) resolution in healthy human subjects. We observed significant CSF flow exclusively with inspiration. In particular, during forced breathing, high CSF flow was elicited during every inspiration, whereas breath holding suppressed it. Only a minor flow component could be ascribed to cardiac pulsation. The present results unambiguously identify inspiration as the most important driving force for CSF flow in humans. Inspiratory thoracic pressure reduction is expected to directly modulate the hydrostatic pressure conditions for the low-resistance paravenous, venous, and lymphatic clearance routes of CSF. Furthermore, the experimental approach opens new clinical opportunities to study the pathophysiology of various forms of hydrocephalus and to design therapeutic strategies in relation to CSF flow alterations

Therapie der blanden Struma: Erfahrungen mit einer Kombination von 100 µg L-Thyroxin und 10 µg L-Trijodthyronin

Dtsch med Wochenschr 1981; 106: 579-583 DOI: 10.1055/s-2008-1070359 © Georg Thieme Verlag KG Stuttgart · New York Therapie der blanden Struma: Erfahrungen mit einer Kombination von 100 µg L-Thyroxin und 10 µg L-Trijodthyronin Treatment of non-toxic goitre: results of combined treatment with 100 µg L-thyroxine and 10 µg L-triiodothyronine C. R. Pickardt, R. Gärtner, J. Habermann, K. Horn, P. C. Scriba, F. A. Horster, H. Wagner, K. Hengst Medizinische Klinik Innenstadt der Universität München, Klinik für Innere Medizin, Medizinische Hochschule Lübeck, Medizinische Klinik C und Poliklinik der Universität Düsseldorf sowie Medizinische Klinik und Poliklinik der Universität Münster Zusammenfassung Bei 96 Patienten mit blander Struma wurde eine offene Prüfung mit einem neuen Schilddrüsenhormonpräparat durchgeführt, das 100 µg L-Thyroxin (T4) und 10 µg L-Trijodthyronin (T3) pro Tablette enthält. Als Parameter für die therapeutisch wirksame Tagesdosis wurde die Suppression des TRH-stimulierten Thyreotropinspiegels im Serum gewählt. Hierbei war eine Tagesdosis von 50 µg T4 und 5 µg T3 bei 16 Patienten unwirksam; 75 µg T4 und 7,5 µg T3waren bei nur 4 von 12 Patienten suppressiv wirksam, während 100 µg T4 und 10 µg T3 bei allen Düsseldorfer und Münsteraner Patienten, aber nur bei 17 von 31 Patienten in München den TRH-stimulierten TSH-Anstieg supprimierte. Während der gesamten Therapiedauer blieben Thyroxin- und Trijodthyroninspiegel im Serum im Normbereich; bei einigen Patienten erhöhte sich der Quotient aus Thyroxin und thyroxinbindendem Globulin über die Norm. Zeichen einer Überdosierung oder Unverträglichkeit wurden nicht beobachtet. In pharmakokinetischen Untersuchungen an acht freiwilligen schilddrüsengesunden Probanden erreichte der mittlere Thyroxin- und Trijodthyroninspiegel etwa 2 Stunden nach Applikation sein Maximum und näherte sich nach sechs Stunden wieder der Norm. Es zeigten sich deutliche individuelle Schwankungen in den ersten Stunden nach Applikation. Wir empfehlen deshalb, Schilddrüsenhormonspiegel erst 12 oder 24 Stunden nach Applikation eines Schilddrüsenhormonpräparates zu bestimmen; zu dieser Zeit sollte auch der TRH-Test durchgeführt werden. Die Untersuchungen bestätigen die Notwendigkeit, bei der Strumatherapie mit einem Schilddrüsenhormonpräparat die suppressiv wirksame Dosis individuell zu ermitteln; diese Dosis beträgt vorzugsweise 100 µg Thyroxin und 10 µg Trijodthyronin oder 150 µg Thyroxin oder 100 µg Thyroxin und 20 µg Trijodthyronin pro Tag.A new thyroid hormone preparation (100 µg L-thyroxine [T4] and 10 µg L-triiodothyronine [T3] per tablet) was given to 96 patients with non-toxic goitre. Suppression of the TRH-stimulated thyrotropin level in serum was chosen as a measure of therapeutic effectiveness. Daily dose of 50 µg T4 and 5 µg T3 was ineffective in 16 patients; 75 µg T4 and 7.5 µg T3 was effective in only four of twelve patients, while 100 µg T4and 10 µg T3 was effective in all patients from clinics in Düsseldorf and Münster, but in only 17 of 31 patients from Munich, in suppressing the TRH-stimulated TSH rise. During the entire period of treatment serum thyroxine and triiodothyronine levels remained normal. In some patients the ratio of thyroxine to thyroxine-binding globulin was above normal. Signs of overdosage or intolerance were not observed. Pharmacokinetic studies on eight volunteers with normal thyroid function demonstrated that the mean thyroxine and triiodothyronine levels reached maximum about two hours after administration, returning towards normal after six hours. There were marked individual variations in the first hours after administration. It is therefore recommended that the thyroid hormone level be determined no earlier than 12 or 24 hours after the thyroid hormone preparation has been administered; TRH test should also be performed at this time. These results indicate the need for determining individually the effective suppressive dose of a thyroid hormone preparation in the treatment of goitre. Preferably the dose should be 100 µg thyroxine and 10 µg triiodothyronine, or 150 µg thyroxine or 100 µg thyroxine and 20 µg triiodothyronine per day