Electrophysiological Effects of Intrapericardial Infusion of Endothelin-1

Recently, extremely high levels of endothelin-1 (ET-1) were detected in the pericardial fluid of patients undergoing open-heart surgery. ET-1 has been suggested to have direct arrhythmogenic effect on myocardium. The aim of the present study was to examine the putative arrhythmogenic effect of intrapericardial infusion of ET-1 in anesthetized dogs (n=15).
In preliminary experiments, ET-1 (0.125–1.0 nmol/min, n=7) was infused into the closed pericardial sack for 40 min. ET-1 induced non-sustained and/or sustained ventricular tachyarrhythmias in all but the lowest dose. For detailed arrhythmia analysis in addition to standard ECG ventricular endocardial and epicardial monophasic action potentials (MAP) were recorded. ET-1 (0.250 nmol/min, n=7) induced mono- and polymorphic ventricular tachycardias, which (degenerated into ventricular fibrillation in two instances. Moderate if any ischemic signs could be detected before the onset of arrhythmias. The arrhythmias spontaneously disappeared in all instances with the exception when ventricular fibrillation terminated the experiment. QT interval (260±23ms vs. 317±31ms, P < 0.05), and endo- and epicardial MAPD₉₀ (at 300 ms cycle length) prolonged significantly (in average 182±12ms vs. 224±25ms, P < 0.05). Using MAP recording afterdepolarizations were detected in three instances. In control animals (n=3) arrhythmias were not observed and all electrophysiological parameters remained unchanged.
The present results show that intrapericardial administration of ET-1 can induce ventricular arrhythmias in dogs. The arrhythmogenic effect of ET-1 may be based on prolongation of MAP duration and development of afterdepolarizations. However, the elucidation of the precise mechanism needs further investigation.     

The effects of daily recombinant human granulocyte colony-stimulating factor administration on normal granulocyte donors undergoing leukapheresis [see comments]

The effects of daily administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) to eight normal volunteers donating granulocytes for neutropenic relatives undergoing marrow transplantation were studied. Granulocyte donors consisted of seven marrow donors (5 syngeneic, 2 HLA identical) and one haploidentical son who had not donated marrow. All donors were administered daily rhG-CSF at a mean dose of 5 micrograms/kg/d (range 3.5 to 6.0) for a mean of 11.75 days (range 9 to 14 days), and granulocytes were collected a mean of 7.6 times (range 4 to 12). RhG-CSF was well tolerated and only minor side effects were observed. All donors became anemic from marrow donation and the removal of red blood cells during the collection procedures. Red blood cell transfusions were not given. All donors had a decrease in platelet counts and the magnitude of the decrement appeared to be greater than in historical donors. This was due in part to increased removal of platelets with the collection product, but a direct effect of rhG-CSF on platelet production cannot be excluded. The mean precollection granulocyte level was 29.6 x 10(9)/L (range 11.8 to 79.8), which was a 10-fold increase over baseline. The mean number of granulocytes collected was 41.6 x 10(9) (range 1.3 to 144.1), which was a six-fold increase over historical donors not receiving rhG-CSF. The mean granulocyte level 24 hours after transfusion into neutropenic recipients was 0.95 x 10(9)/L (median 0.57 and range .06 to 9.47). This study indicates that rhG-CSF is safe to administer to normal individuals, significantly improves the quantity of granulocytes collected, and results in significant circulating levels of granulocytes in neutropenic recipients. Further studies to evaluate rhG- CSF in normal granulocyte donors are warranted.     

Selective induction of a glycoprotein IIIa ligand-induced binding site by fibrinogen and von Willebrand factor

Ligand-induced binding sites (LIBS) are neoantigenic regions of glycoprotein (GP)IIb-IIIa that are exposed upon interaction of the receptor with the ligand fibrinogen or the ligand recognition sequence (RGDS). LIBS have been suggested to contribute to postreceptor occupancy events such as full-scale platelet aggregation, adhesion to collagen, and clot retraction. This study examined the induction requirements of a GPIIIa LIBS with regard to ligand specificity. Through the use of the anti-LIBS D3, we report that this complex- activating antibody induces fibrinogen- and von Willebrand factor- binding to GPIIb-IIIa on intact platelets. Bound ligand was detected by flow cytometric analysis and platelet aggregation assays. These bound ligands increased the number of D3-binding sites and altered the affinity of D3 for GPIIb-IIIa on platelets. In contrast, activation of platelet GPIIb-IIIa by D3 did not increase the binding of another RGD- containing ligand, vitronectin. Furthermore, bound vitronectin on thrombin-stimulated platelets did not cause the expression of the D3 LIBS epitope. We conclude direct activation of GPIIb-IIIa in the absence of platelet activation results in selective ligand interaction and that D3 LIBS induction requires the binding of the multivalent ligands, fibrinogen or von Willebrand factor. Thus, the region of GPIIIa recognized by D3 may be an important regulatory domain in ligand- receptor interactions that directly mediate platelet aggregation.     

Characterization of epitopes on the 25 kD protein of the macrogametes/zygotes of Plasmodium falciparum

A sexual stage-specific protein of Plasmodium falciparum with a Mr of 25,000 is one of the target antigens of transmission-blocking antibodies. The contributions of tertiary structure and post-translational modifications (glycosylation and acylation) to the structure of the epitopes on this protein were the subject of detailed investigations. After modification of the three-dimensional structure and modification or cleavage of carbohydrate groups and linked fatty acids, the immunological reactivity was investigated by three different techniques: (i) immunoprecipitation of radiolabelled proteins, (ii) enzyme-linked immunosorbent assay (ELISA), and (iii) Western blotting. The results of the experiments indicate that the immunological reactivity of the major epitopes on the 25 kD protein, including the epitope involved in transmission-blocking immunity, are dependent on the tertiary structure of the protein and on the presence of linked fatty acids, but not on the presence or absence of carbohydrate groups.     

Towards a Psychosis Risk Blood Diagnostic for Persons Experiencing High-Risk Symptoms: Preliminary Results From the NAPLS Project

Introduction: A barrier to preventative treatments for psychosis is the absence of accurate identification of persons at highest risk. A blood test that could substantially increase diagnostic accuracy would enhance development of psychosis prevention interventions. Methods: The North American Prodrome Longitudinal Study project is a multisite endeavor that aims to better understand predictors and mechanisms for the development of psychosis. In this study, we measured expression of plasma analytes reflecting inflammation, oxidative stress, hormones, and metabolism. A “greedy algorithm” selected analytes that best distinguished persons with clinical high-risk symptoms who developed psychosis (CHR-P; n = 32) from unaffected comparison (UC) subjects (n = 35) and from those who did not develop psychosis during a 2-year follow-up (CHR-NP; n = 40). Results: The classifier included 15 analytes (selected from 117), with an area under the receiver operating curve for CHR-P vs UC of 0.91 and CHR-P vs CHR-NP of 0.88. Randomly scrambled group membership followed by reconstructions of the entire classifier method yielded consistently weak classifiers, indicating that the true classifier is highly unlikely to be a chance occurrence. Such randomization methods robustly imply the assays contain consistent information distinguishing the groups which was not obscured by the data normalization method and was revealed by classifier construction. These results support the hypothesis that inflammation, oxidative stress, and dysregulation of hypothalamic-pituitary axes may be prominent in the earliest stages of psychosis. Conclusion: If confirmed in other groups of persons at elevated risk of psychosis, a multiplex blood assay has the potential for high clinical utility.Key words: clinical high risk, psychosis, prodrome, multiplex, risk prediction, malondialdehyde-modified low-density lipoprotein (MDA-LDL), immune, inflammation, oxidative stress     

Toxicoepidemiology of acute poisoning cases in a secondary care hospital in rural South India: A five-year analysis

Objective:

To ascertain the trend of poisoning cases admitted to the Government District Headquarters Hospital, a secondary care center in Udhagamandalam, Nilgiris District, Tamil Nadu, India, over a five-year period.

Materials and Methods:

The number of cases that presented to the hospital annually (incidence, mortality, and case fatality rates), socio-demographic pattern, and the nature of the poison were noted.

Results:

A total of 1860 poisoning cases (80 deaths) were reported during the period from October 2008 to September 2013. The incidence of poisoning was found to increase every year. The average incidence was 1.60 per 1000 population, while the average case fatality rate and mortality rates were 40.51 and 0.07, respectively. A total of 1148 (62%) were males. The majority of cases were seen in the 21-30 age group (41.24%). The poisonings were largely deliberate self-harm (n = 1,755; 94.35%), followed by accidental (n = 85; 4.57%). Agrochemicals were the main choice of poisoning agents and among these, organophosphates were the major cause.

Conclusion:

The data generated can help policy makers take decisions on the sale and availability of pesticides in this region.KEY WORDS: Choice of poison, mortality rate, Nilgiris population, organophosphate poisoning, surveillance     

VERTEBRAL OSTEOPOROSIS IN RHEUMATOID ARTHRITIS PATIENTS: EFFECT OF LOW DOSE PREDNISONE THERAPY

The effect of low dose prednisone therapy on spinal bone massis controversial. We measured lumbar trabecular and corticalbone mineral density (BMD) in 74 rheumatoid arthritis (RA) patientsby dual energy quantitative computerized tomography in a cross-sectionalstudy. The presence of vertebral deformities was evaluated ona lateral spine radiograph. Patients who had never been treatedwith corticosteroids (n=44) were compared with patients on long-termlow dose ( 10 mg/day) prednisone therapy (n=30). After correctionfor confounding variables the lumbar BMD was highly sig nilicantlyinfluenced by prednisone therapy in postmenopausal patients(estimated influence –31.2% on trabecular BMD and –37.2%on cortical BMD). Vertebral deformities were also significantlymore frequent in prednisone treated postmenopausal patients.No negative effect of prednisone treatment could be demonstratedin male patients. In contradiction to previous reports we concludethat long-term prednisone therapy may be associated with developmentof spinal osteoporosis in postmenopausal RA patients, even whenlow doses are used. KEY WORDS: Corticosteroids, Osteoporosis, Bone densitometry, Dual energy quantitative computerized tomography, Vertebral fractures, Postmenopause     

The effect of respiration on diastolic blood flow velocities in the human heart

This study was performed to evaluate the effects of respirationon diastolic blood flow velocity and its relevance for the determinationof pulsed Doppler reference values from diastolic blood flow.Doppler signals were recorded from both the atrial and ventricularsides of the mitral valve and the tricuspid valve in 215 healthyvolunteers (120 males and 95 females, with ages ranging from1–65 years). Respiratory signals were recorded simultaneouslyby a mercury strain gauge around the thorax. From the mediansof Doppler spectra the _maxmaximum velocity during early diastole(V_maxE), during atrial contraction (V_maxA) and the ratio betweenV_maxE and V_maxA (EA ratio) were obtained. On the atrial side of the tricuspid valve, V_maxE and V_maxA weresignificantly higher during inspiration than during expiration.On the ventricular side of the tricuspid valve, this was onlyfound for V_maxE. On the atrial side of the mitral valve, V_maxEand V_maxA were significantly lower during inspiration than duringexpiration. At the ventricular side of the mitral valve, thiswas found only for V_maxE. No significant effect of respirationwas found on the EA ratio. We conclude that there is a respiration-related effect on V_maxEand V_maxA. However, no significant effect is found on the EAratio. Thus, for the determination of the EA ratio in intersubjectstudies, information about the respiratory cycle is not relevant.     

A novel deletion of approximately 27 kb including the beta-globin gene and the locus control region 3'HS-1 regulatory sequence: beta zero- thalassemia or hereditary persistence of fetal hemoglobin?

A novel deletion of approximately 27 kb with the 5' breakpoint 1.5 to 2.2 kb upstream of the beta-globin gene, and the 3' breakpoint approximately 24 kb downstream of the beta-globin gene, has been found in five members of two families from Southeast Asia (Vietnam and Cambodia). Six members of another family from China, previously reported from our laboratory, have also been shown to carry this deletion. The patients presented with mild hypochromia and microcytosis, a hemoglobin (Hb) A2 level of approximately 4.0%, and a markedly increased, heterocellularly distributed, Hb F level (14.0 to 26.0%). In vitro globin-chain synthesis showed a mild imbalance with appreciable gamma-chain compensation (alpha/beta + gamma ratio of 1.46). The 3' end of this deletion includes the 3'HS-1, and we hypothesize that removal of this region results in the loss of its gamma-globin gene-silencing effect, which causes a markedly elevated Hb F level with a modest increase in Hb A2 levels, unlike the situation in other deletional beta zero-thalassemias. The possible influence of particular sequence variations in the locus control region 5'HS-2 and the G gamma promoter, present on the chromosome with this deletion, on the overall gamma-globin gene should also be considered.