Adverse Effect of Raised Environmental Temperature on the Expression of Hereditary Spherocytosis in Deer Mice

Deer mice with a compensated hemolytic syndrome caused by hereditaryspherocytosis were placed in a controlled temperature room at 35 C. Severeanemia, red cell fragmentation, increased osmotic fragility, occasional jaundiceand hemoglobinuria were observed. The spleen enlarged and the erythropoietic bone marrow expanded. Reticulocytes fell markedly early during heat exposure, but in survivors soon increased to levels higher than those observedprior to experiment. Mortality from the severe acceleration of the preexistinghemolysis was high. Control nonspherocytic deer mice subjected to an identical temperature showed only a mild drop of hemoglobin and slight elevationof reticulocytes.

Since hereditary spherocytosis in deer mice in a temperate climate is compatible with good health, these findings provide a further illustration of interaction of a particular environmental insult with a specific genotype in thepathogenesis of hereditary disease.

Submitted on December 10, 1965 Accepted on January 10, 1966     

Steady-State and Dynamic Behavior of Ventricular Repolarization and Refractoriness in the Dog: The Effect of Multiple Cycle Length Changes and d-Sotalol Administration

In anesthetized dogs with chronic, complete AV block we studied the characteristics of ventricular repolar-ization and refractoriness. Therefore, we determined: (1) steady-state values of ventricular effective refractory period (VERP), action potential duration (APD), and stimulus T interval (STI) before and after d-sotalol treatment at various pacing cycle lengths (PCLs); and (2) the dynamics of VERP, APD, and STI before and after d-sotalol treatment after the abrupt PCL decreases. VEHP, APD, and STI showed a normal frequency dependency. All three parameters increased significantly after d-sotalol administration. During steady-state and dynamic measurements, STI was always longer than APD and APD was always longer than VERP in an individual animal, irrespective of PCL and conditions. Standard deviations of steady-state and dynamic values indicated a considerable interindividual variation. However, the dynamics of VERP, APD, and STI after an abrupt decrease in PCL were highly correlated (linear regression analysis: r²± 0.93). The best mathematical model to describe these dynamics was a bi-exponential model (r²± 0.98) with a very short first and a much longer second time constant. We found that there was a very consistent relation between VERP, APD, and STI, not only during steady-state but also in the dynamic situation after various abrupt PCL decreases. This relation does not change after the administration ofd-so-talol. Therefore, STI could be used to predict steady-state and dynamic values of VERP and APD. Since STI can be made available online in implantable pacing systems this could lead to the development of new features in these devices.     

Characterization of phenotype related responsiveness of peripheral blood lymphocytes from Eimeria tenella infected chickens

We have previously shown that the proportion of CD8-expressing T cells (CD8^bright+ and CD4⁺ CD8^dim+ cells) in the peripheral blood of chickens increases around 8 days after a primary infection with Eimeria tenella oocysts. The increase in the CD8⁺ eight cells coincides with enhanced responses after in vitro stimulation with parasite antigen. In the study described here, the responsiveness of these day 8 PBL was further characterized by determining their capacity to proliferate and to produce cytokine (IFN-γ) upon stimulation with E. tenella sporozoite antigen, or non-specific stimuli like T cell growth factor (TCGF) and anti-CD3 monoclonal antibody (MoAb). Comparing the responsiveness of infected responder (day 8) and control chickens, non-specific triggering induced cytokine production in cells from infected animals and proliferation in cells from control animals. When triggered with E. tenella sporozoite antigen, lymphocytes from infected chickens responded with proliferation and cytokine production, in contrast to lymphocytes from control animals that did not respond. The phenotype of the lymphocytes involved in the parasite-specific proliferation and cytokine production, was characterized in a blocking assay using MoAb directed against the CD4 or CD8 molecule. The results suggest that CD8^bright+ as well as CD4⁺ (CD4⁺ CD8^dim+ and possible CD4⁺, single positive) lymphocytes are responsible for the IFN-γ production measured after stimulation with parasite antigen, whereas the specific proliferative response appears to be caused by CD4⁺ (CD4⁺ CD8^dim+ and possibly CD4⁺, single positive) lymphocytes. We speculate that the CD8^bright+ cells, present in the circulation around 8 days after a primary E. tenella infection, act as effector cells in protective immune responses, whereas CD4⁺ cells play an important helper function in these responses.     

A systematic approach to the solid-phase synthesis of linear and cyclic pseudopeptide libraries containing ψ[CH2NH] amide bond surrogates

A systematic approach has been adopted for the synthesis and characterization of a series of linear and cyclic pseudopeptide mixtures containing the ψ[CH₂NH] amide replacement. The parent structures were based on biologically relevant compounds including an enkephalin analog, H-Tyr-d -Ala-Gly-Phe-Leu-OH, and an Arg-Gly-Asp peptide sequence. The linear mixtures containing 4 and 64 pseudopeptide components with 1, 2 or 3 amide bond surrogates were synthesized using Boc-SPPS. The amount of desired linear pseudopeptides in the mixtures ranged from 67 to 90% as determined by integration of HPLC peak areas. Comparative studies indicated: (i) racemization is not a problem in the synthesis of pseudopeptide mixtures containing the ψ[CH₂NH] surrogate; and (ii) protection of the ψ[CH₂NH] surrogate with a benzyloxycarbonyl group during the synthesis is beneficial. Cyclic mixtures containing 4 and 256 cyclic pseudopeptide components with a single amide bond surrogate were synthesized using a resin-bound cyclization approach featuring side-chain attachment of Boc-Asp-OFm to the solid support. Cyclization kinetic studies revealed that the newly developed HATU coupling reagent provided a fast cyclization rate for a pseudopeptide mixture and that the position of the reduced peptide bond within a peptide mixture had only a small effect on the cyclization rates of the mixture. Pseudopeptide libraries permit the more efficient bioassay of complex structures and can also be used to reveal more rapidly trends in physicochemical variables. For example, we observed that the expected increase in hydrophilicity with ψ[CH₂NH] substitutions during RP-HPLC analysis did not continue with several such replacements. © Munksgaard 1997.     

Liver Damage in Nurses Handling Cytostatic Agents

ABSTRACT. Three consecutive head nurses developed liver injury after years of handling cytostatic drugs. They had neurological symptoms associated with elevated serum alanine amino-transferase (ALAT) and alkaline phosphatase (ALP) levels. Liver histology showed portal hepatitis with piecemeal necrosis in one of them, the others had hepatic fibrosis and fat accumulation. The subjects' livers were metabolically active as reflected by adaptive and toxic changes in cellular ultrastructure. After withdrawal of the drugs, serum ALAT and ALP values fluctuated between normal and 2–3 times elevated. Follow-up biopsies demonstrated an increase in collagen fibres and a decrease in microsomal enzyme activity, as reflected by arylhydrocarbon hydroxylase activity in vitro. The findings suggest that handling of cytostatic drugs may insidiously damage the liver, which, with time, seems to lead to irreversible fibrosis.     

Backbone modifications in cyclic pep tides Conformational analysis of a cyclic pseudopentapeptide containing a thiomethylene ether amide bond replacement

NMR and X-ray crystallographic studies have shown that cyclic pentapeptides of the general structure cyclo(D-Xxx-Pro-Gly-Pro-Gly) possess β- and γ-turn intramolecular hydrogen bonds. As part of our continuing series surveying the compatibility of various amide bond replacements on peptide structure, we have synthesized cyclo(D-Phe-Proψ [CH₂S]Gly-Pro-Gly). The pseudopeptide was prepared by solid phase methods and cleaved from the resin by a new procedure involving phase transfer catalysis using K₂CO₃ and tetrabutylammonium hydrogen sulfate. Cyclization was carried out with the use of DPPA, HOBt, and DMAP to afford the product in 69% yield. The conformational behavior of the pseudopeptide was analyzed by ¹H and ¹³C (1D and 2D) NMR techniques. The backbone modification replaced the amide bond that is involved in a γ-turn intramolecular hydrogen bond in the all-amide structure. In CDCl₃, the pseudopeptide adopted the same all-trans conformation as its parent, although the remaining β-turn hydrogen bond was weaker according to Δδ/ΔT_NH measurements. In DMSO-d₆, the all-trans conformer and a second conformer were observed in a ratio of 55:45. These conformers, which slowly inter converted on the NMR time scale, could be separately assigned; peaks due to chemical exchange were readily distinguishable by the ROESY technique as reported earlier by others. ¹³C and ROESY experiments suggested the minor conformer contained one cis amide bond at the Gly¹-Pro² position. Thus, both the location and type of amide surrogate are important determinants affecting the compatibility of the replacement with a particular conformational feature.     

Does Increased Maternal Pacoa During General Anaesthesia for Caesarean Section Improve Foetal Acid-Base Parameters?

Das Untersuchungsmaterial bestand aus 27 Schwangeren, welche entweder am Termin oder knapp davor standen, bei denen aus geburtshilflichen Gründen eine Sectio in Allgemeinnarkose gemacht wurde.
Gruppe A (11 Patientinnen) bestand aus gesunden Frauen und Gruppe B (10 Patientinnen) aus Müttern, deren Anamnese auf eine uteroplazentare Insuffizienz hindeutete. Gruppe C (6 Patientinnen) dienten als Vergleichsgruppe ohne Anhaltspunkte für uteroplazentare Insuffizienz.
Allgemeinnarkose wurde mit Pentothal, Suxamethonium und Lachgas-Sauerstoff-anaesthesie durchgeführt und kontrollierte Beatmung wurde dazu benutzt. In den Gruppen A und B begannen die Patientinnen 90 % Sauerstoff und 10 % CO₂ zu atmen, und zwar 5 Minuten vor der Narkose-einleitung bis zum Augenblick der Geburt (15 Minuten später). In Gruppe C bekamen die Patientinnen kein CO₂-hältiges Gemisch.
Die miitterlichen und kindlichen Säure-Basen-Parameter (pH und BD) wurden im mütterlichen arteriellen und fotalen kapillären Blut (S aling 1962) bestimmt und zwar vor Beginn der CO₂-Atmung und bei der Geburt.
Das mütterliche und fötale Pac0₂ nahm in den Gruppen A und B signifikant zu. Mutter und Kind entwickelten eine sekundäre metabolische Azidose, welche in Gruppe B zu einem klaren Abfall des fötalen Nabelarterien-pH führte. In Gruppe A blieb das Nabelarterien-pH innerhalb des physiologischen Bereiches.
Der miitterlich-fötale pH-Gradient, der normalerweise bei der Geburt besteht, nahm in Gruppe A während der CO₂-Atmung deutlich ab und verschwand vollständig in Gruppe B, während in der Kontrollgruppe C dieser Gradient bestehen blieb.