Vaccination of the Leishmania major susceptible BALB/c mouse. I. The precise selection of peptide determinant influences CD4+ T cell subset expression

BALB/c mice are susceptible to cutaneous lelshmanlasls uponinfection with Leishmania major while C57BL/6 are not. Thereis a major promastigote surface protease (PSP or gp63) whichis available in both native and recomblnant forms, and for whichthe primary amlno acid sequence is known. Immunization withPSP has been shown to offer some protection against challengewith the live organism. Therefore, we attempted to develop apeptide vaccine with PSP peptldes. In the first experiments,recall prollferatlve responses to PSP were measured using aset of 15mer peptldes spanning the entire PSP molecule whichallowed designation of major determinant regions in BALB/c,C57BL/6, and CBA mice. Several of these determinants were promiscuousand shared almost the identical core amlno acid residues inthe different strains. Immunization with major determinant peptldeswas recalled vigorously with L. major soluble antigen as wellas with PSP. The response to peptide was almost entirely T_h1as measured by a localized ELISA assay for single-cell productionof IFN-. A similar assay for IL-5, which overcomes problemsof sensitivity and inhibition by lymphoklnes produced by T_h1cells, Indicates very little production of T_h1 cells even byBALB/c. It was found that if a major responsive peak was examinedby recall with overlapping peptldes, the highest, central peptidegave a mainly Th1 response while the boundary, less efficientpeptldes gave more of a T_h2 response. Possible reasons for thiswere discussed. These results point to the importance of selectingthe exactly appropriate peptide in considering a vacclnogenthat might protect susceptible individuals. Even the choiceof a somewhat immunogenlc peptide within the determinant envelopemight actually exacerbate infection by steering the responsein a T_h2 direction.     

Relapse of major depression after complete and partial remission during a 2-year follow-up

BACKGROUND: Rates of remission and relapse were studied over more than 2 years in a sample of Spanish outpatients with DSM-III-R criteria of unipolar major depressive episodes. METHODS: Patients were treated following standardised pharmacological protocols at our centre. In the first visit, the structured clinical interview for DSM-III-R (SCID) was used. The following visits were held monthly. Phases of evolution were recorded using the Hamilton Depression Rating Scale (HDRS), applying the Frank criteria. RESULTS: A significantly greater proportion of relapse was observed in the partial remission group compared to the complete remission one. The rate of relapses for patients in complete remission was 15.18%, while for patients in partial remission was 67.61%. Partial remission was significantly associated with relapses. LIMITATIONS: The short duration of the study and the decreasing sample size during the follow-up. CONCLUSIONS: Partial remission after a depressive episode seems to be strongly associated with relapses. Moreover, this clinical factor could by itself fully predict short-term relapses. CLINICAL RELEVANCE: The study shows the importance of reaching complete remission to decrease the rate of short-term relapses.     

Hemostatic coronary risk factors in a healthy population of Maracaibo,Venezuela

The purpose of the present work was to determine the plasma concentrations of fibrinogen and Von Willebrand Factor (VWF) as well as platelet aggregation, in an apparently healthy population of 306 men and 41 women, 33 to 65 years of age, workers of the national oil industry (PDVSA, Maracaibo), as a base investigation in a 5-year prospective national collaborative study. The participants were previously subjected to a thorough clinical examination with cardiovascular evaluation and laboratory tests. Clottable fibrinogen and VWF concentrations were determined in platelet poor plasma, the last one by immunoclectrophoresis, and a multimeric analysis of VWF was performed on those plasmas with concentrations higher than 150 U/dL by SDS agarose electrophoresis, followed by cellulose membrane transference. Platelet aggregation was studied in platelet rich plasma with no addition of stimulants and after collagen and ristocetin were added. Forty per cent of men and 65.8% of women, showed fibrinogen concentrations above 300 mg/dL (p < 0.01) and 12.2% of men and 15.4% of women had VWF values higher than 150 U/dL, with normal multimeric distribution. Fourteen individuals presented spontancous platelet aggregation and increased aggregation in 12 and 13 of them, after induction with collagen and ristocetin respectively. Comparing these findings with those of previous collaborative studies from other countries, the present results could mean that an important proportion of the population here studied, could be at risk for a future coronary event; however, as these are the base findings in Maracaibo, the significance of our results will be better evaluated at the end of the five year study.     

Latent infection of monkeys with oncogenic herpes viruses

Herpesvirus saimiri induced a latent infection in monkeys (Callithrix jacchus, Aotus trivirgatus) without development of a clinical disease. The animals are now under observation for one year. The virus can be isolated from the peripheral white blood cells after in vitro cultivation or after cocultivation with permissive indicator cells. The virus genome was transmitted with lymphocytes from a latent infected owl monkey (Aotus trivirgatus) to a CT-marmoset (S. oedipus) and to another owl monkey. Both recipients died of malignant lymphoma. Two Callithrix jacchus monkeys developed a latent infection withH. ateles after transplantation of tumor cells. The virus isolated from the peripheral white blood cells proved to be oncogenic in a CT-marmoset. The malignant lymphomas which may develop in the investigated species seem to require in their etiology a certain cofactor in addition to the herpesvirus. This cofactor is not species dependent.

---

Zusammenfassung Die Inoculation vonHerpesvirus saimiri induzierte eine latente Infektion in Affen (Callithrix jacchus, Aotus trivirgatus), ohne daß eine Erkrankung klinisch bemerkbar wurde. Die Tiere sind nunmehr seit 1 Jahr unter Beobachtung. Das Virus kann aus den peripheren weißen Blutzellen nach deren Kultivationin vitro oder aber nach deren Kokultivation mit permissiven Indicatorzellen isoliert werden. Das Virusgenom wurde mit Lymphocyten von einem latent infizierten Eulenaffen (Aotus trivirgatus) in einen Marmoset-Affen (S. oedipus) und in einen weiteren Eulenaffen übertragen. Beide Empfängertiere starben an einem malignen Lymphom. Zwei Callithrix jacchus-Affen entwickelten eine latente Infektion mitH. ateles nach Tumorzelltransplantation. Das von den peripheren Blutzellen isolierte Virus erwies sich als onkogen in einem Marmoset-Affen. Für die Induktion eines malignen Lymphoms scheint bei den genannten Affenspecies ein Kofaktor zusätzlich zum Herpesvirus erforderlich zu sein. Der Kofaktor ist nicht speciesspezifisch.

---

---

This investigation was supported by the Deutsche Forschungsgemeinschaft, Bad Godesberg.     

Effect of sensory stimulus on striatal dopamine release in humans and cats: a [(11)C]raclopride PET study

BACKGROUND: Sensory stimulation of the forelimb extremities constitutes a well-established experimental model that has consistently shown to activate dopamine (DA) neurotransmission in the mammals' forebrain. OBJECTIVES: To visualize in vivo this modification of striatal DA release in healthy human volunteers using Positron Emission Tomography (PET) and [(11)C]raclopride. Experiments in humans were paralleled by experiments in anesthetized cats. Changes in endogenous DA release were assessed through its competition with [(11)C]raclopride binding (BP(raclo)), a radioligand probing DA D2-receptors. RESULTS: In humans no significant difference of BP(raclo) in caudate (with sensory stimulation: 2.0 +/- 0.3 versus without sensory stimulation: 2.2 +/- 0.3; P = 0.3) or putamen (2.6 +/- 0.3 versus 2.6 +/- 0.2; P = 0.9) ipsilateral to the stimulus was disclosed as a result of sensory stimulation. Similarly, no change of BP(raclo) was observed contralaterally to the stimulation in the caudate nucleus (with sensory stimulation: 2.0 +/- 0.4 versus without sensory stimulation: 2.1 +/- 0.2; P = 0.5) and the putamen (2.5 +/- 0.4 versus 2.6 +/- 0.2; P = 0.4). In cats the same results were obtained in the ipsilateral to stimulation striatum (with sensory stimulation: 2.5 +/- 0.03 versus without sensory stimulation: 2.4 +/- 0.05; P = 0.7). No change was also observed contralaterally to the stimulation (2.4 +/- 0.04 versus 2.5 +/- 0.06; P = 0.6). The [(11)C]raclopride binding remained unchanged by sensory stimuli in both humans and cats. CONCLUSION: This suggests that the DA release induced by sensory stimulus is mostly extrasynaptic whereas the synaptic DA release is probably small, which fits well with the absence of [(11)C]raclopride displacement. The mechanism of this extrasynaptic DA release could be related to a local action of glutamate on dopaminergic terminals via a thalamo-cortico-striatal loop. Present results also underline homology between cat and human responses to sensory stimuli and validate the use of cat brain to find physiological concepts in humans.     

Cell signalling-mediating insulin increase of mRNA expression for cationic amino acid transporters-1 and -2 and membrane hyperpolarization in human umbilical vein endothelial cells

Insulin induces vasodilatation in human subjects and increases l-arginine transport and NO synthesis in human umbilical vein endothelial cells (HUVEC). Cell signalling events associated with insulin effects on activity and mRNA expression of the human cationic amino acid transporters 1 (hCAT-1) and 2B (hCAT-2B) are unknown. l-Arginine transport and eNOS activity were determined in HUVEC exposed to insulin. mRNA levels for hCAT-1, hCAT-2B and eNOS were quantitated by real time RT-PCR and endothelial NO synthase (eNOS) protein was identified by Western blot analysis. Intracellular Ca²⁺, l-arginine and l-citrulline levels, l-[³H]citrulline formation from l-[³H]arginine, cGMP formation, nitrite level, ATP release and membrane potential were determined. Insulin increased l-arginine transport and the mRNA levels for hCAT-1 and hCAT-2B and eNOS expression and activity. Insulin also induced membrane hyperpolarization and increased intracellular Ca²⁺, l-[³H]citrulline, cGMP and nitrite formation. Insulin-mediated stimulation of the l-arginine/NO pathway is thus associated with increased hCAT-1 and hCAT-2B mRNA, and eNOS expression, via mechanisms involving membrane hyperpolarization, mitogen-activated protein kinases p42 and p44, phosphatidylinositol 3-kinase, NO and protein kinase C. We have characterized a cell signalling pathway by which hyperinsulinaemia could lead to vasodilatation in human subjects, and which could have implications in patients in whom plasma insulin levels are altered, such as in diabetes mellitus.     

Interpolymer association between poly(vinylpyridines) and poly(mono-n-alkyl itaconates). Effect of the n-alkyl substituent

The binary polymeric systems formed by some poly(mono-n-alkyl itaconates) and poly(2-vinylpyridine) or poly(4-vinylpyridine) are studied. Depending on the solvent, two different types of material have been synthesized. On the one hand, using methanol as common solvent, we have obtained solid polymer-polymer complexes the composition of which is determined by the initial mixing conditions. On the other hand, pyridine avoids the complexation process, allowing to obtain a true solution of both polymers and, therefore, a solid polymer blend of known composition by solvent casting. Yields of the complexation and stoichiometries of the polymer-polymer complexes have been analysed. In this way, a favoured composition in the range from 3:2 to 1:1 for the mole ratio (referring to repeating units) ratio poly(mono-n-alkyl itaconate):poly(vinylpyridine) was observed depending on the poly-(mono-n-alkyl itaconate used). Differential Scanning Calorimetry and thermogravimetry have been employed to study the thermal behaviour of complexes and blends. Viscometry measurements have been performed to analyse the interactions in solution. One of the aims of this work has been to analyse the effect of the side group of the poly-(mono-n-alkyl itaconate) in the mixing process as well as in the characteristics of the final products. In this way, higher complexation yields have been obtained using poly-(mono-n-alkyl itoconates) with longer n-alkyl side groups due to the additional stabilisation by solvophobic interactions. On the other hand, the poly(mono-n-alkyl itaconates) with longer n-alkyl groups form polymer-polymer complexes with a higher proportion of poly(4-vinylpyridine), presumably due to their slower kinetics of complexation.     

Implementation of a gastrostomy care bundle reduces dislodgements and length of stay

PurposePediatric gastrostomy tubes (G-tubes) are associated with considerable utilization of healthcare resources. G-tube dislodgement can result in tract disruption and abdominal sepsis. We aimed to reduce early G-tube dislodgement by 25%.MethodsAn interdisciplinary team convened to identify key drivers of G-tube dislodgement and implement initiatives to reduce this complication. A G-tube care bundle was implemented in 2018. Rates of early G-tube dislodgement (within 90 days of insertion) were tracked. 15 months of cases after bundle implementation were compared to 20 months of cases before implementation. Length of stay (LOS, balancing measure) and bundle compliance (process measure) were tracked.ResultsG-tube dislodgements decreased 47% after bundle implementation. Overall, dislodgements after G-tube insertion decreased from 43% to 19% dislodgements per tube inserted, p = 0.004. Reductions were observed for dislodgements occurring in both the inpatient (14% vs. 1.5%) and outpatient (29% vs. 18%) settings. Median LOS was reduced from 15.3 to 7.1 days following implementation, p = 0.004. Process measures demonstrated 75% or greater compliance one year after implementation.ConclusionAn interdisciplinary team using quality improvement science methodology can significantly reduce G-tube dislodgement and improve value after pediatric gastrostomy tube insertion.Type of studyLongitudinal cohort study.Level of evidenceIII.