Quantitative analysis of myocardial blood flow in surgically revascularized and not revascularized myocardial segments. A pilot PET study

PURPOSE

To prospectively compare changes in myocardial blood flow (MBF) and myocardial flow reserve (MFR) in multivessel coronary artery disease (MVCAD) patients undergoing incomplete revascularization (IR) versus complete revascularization (CR) by coronary artery bypass grafting (CABG).

METHODS

Seven male patients (age 68 ± 9 years) with MVCAD underwent myocardial perfusion PET/CT with [13N]ammonia before and at least 4 months after CABG. Segmental resting and stress MBF as well as MFR were measured. Resting and during stress left ventricle ejection fraction (LVEF) were also calculated.

RESULTS

Three patients (43%) underwent CR and four (57%) IR. Among 119 myocardial segments, 101 (85%) were revascularized, and 18 (15%) were not. After CABG, stress MBF (mL/min/gr) and MFR are significantly increased in all myocardial segments, with a greater increase in the revascularized segments (p = 0.013). In both groups, LVEF significantly decreased during stress at baseline PET (p = 0.04), but not after CABG.

CONCLUSION

Stress MBF and MFR significantly improve after CABG in both revascularized and not directly revascularized myocardial segments. IR strategy may be considered in patients with high surgical risk for CR.

Global longitudinal strain for prediction of mortality in ST-segment elevation myocardial infarction and aortic stenosis patients: two sides of the same coin

OBJECTIVE

Global longitudinal strain (GLS) predicts major adverse events in ST-segment elevation myocardial infarction (STEMI) and aortic stenosis (AS). Different cut-off values and different end-points have been proposed for prognostic stratification. We aimed to verify whether a single GLS cut-off value can be used to identify increased risk of all-cause death in STEMI and AS.

PATIENTS AND METHODS

One-hundred- seventeen successfully treated first STEMI (age 63.8±12.5 yrs, 70% men) and 64 AS (age 80.3±6.9 yrs, 44% men) patients, undergoing echocardiography before discharge and before AS treatment, respectively, were retrospectively analyzed. GLS was analyzed, together with pulmonary artery systolic pressure (PASP), Killip class and Genereux stage. End-point was all-cause death at 6-month follow-up.

RESULTS

All-cause death occurred in 4 (3.4%) STEMI and 5 (7.8%) AS patients (p=ns). AS patients who died had GLS similar to died STEMI patients (9.7±2.1 vs. 11.3±1.7, p=ns). GLS cut-off ≤12% predicted death with 89% sensitivity and 70% specificity (AUC 0.84, p=0.001): STEMI and AS patients with GLS ≤12% had worse survival than STEMI and AS patients with GLS >12% (log-rank p=0.001). At multivariate Cox regression analysis, lower GLS values independently predicted death (HR 0.667, 95% CI 0.451-0.986, p=0.042), and the prediction model was improved when GLS was added to old age, significant comorbidities, PASP and Killip/Genereux stage (χ2 6.691 vs. 1.364, p=0.010).

CONCLUSIONS

Died patients with STEMI and AS show similar values of GLS. A unique cut-off value of GLS can reliably be used to stratify the risk of all-cause death at 6-month follow-up in both two clinical settings.

Acute hemodynamic impact of transcatheter aortic valve implantation in patients with severe aortic stenosis

Funding Acknowledgements

Type of funding sources: None.

Background. There are limited data about the intraprocedural hemodynamic study performed immediately before and after transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis (AS). Purpose. We aimed to evaluate the acute hemodynamic impact of TAVI in patients with severe AS and to investigate invasive and non-invasive parameters predicting all-cause mortality. Methods. A total of 245 consecutive AS patients undergoing TAVI were enrolled. Intraprocedural left heart catheterization (LHC) and echocardiogram before and after TAVI were performed. The clinical endpoint was the death for any cause. Results. LHC after TAVI revealed significant changes in aortic and LV pressures, including indexes of intrinsic myocardial contractility and diastolic function such as positive dP/dT (1128.9 ± 398.7 vs 806.3 ± 247.2 mmHg/sec, p˂0.001; Figure 1A) and negative dP/dT (1310.7± 431.1 vs 1075.1 ± 440.8 mmHg/sec, p˂0.001; Figure 1B). Post TAVI echo showed a significant reduction in LV end diastolic volume index (54.6 ± 18.4 ml/m2 vs 51.7 ± 17.5 ml/m2; p = 0.017; Figure 1C), improvement in left ventricle ejection fraction (from 55 ± 12 to 57.2 ± 10.5%, p˂0.001; Figure 1D) and pulmonary artery systolic pressure (42.1 ± 14.2 vs 33.1 ± 10.7 mmHg, p < 0.001; Figure 1E). After a mean follow-up time interval of 24 months, 47 patients died. Post-TAVI aortic regurgitation (2- 3- 4+) at echocardiography was the only independent predictor of mortality (HR 4.43, C.I. 1,71 – 11,45, p = 0.002; Figure 2). Conclusions. LHC performed immediately before and after prosthesis release offers a unique insight in the assessment ofLV adaptation to severe AS and the impact of TAVI on LV, catching changes in indexes of intrinsic contractility and myocardial relaxation. Aortic regurgitation assessed by echocardiography was the only independent predictor of mortality in patients undergoing TAVI.

FIGURE LEGEND

Figure 1. A-B: Impact of TAVI on haemodynamic parameters: Box plot with median and interquartile ranges of positive dP/dT and negative dP/dT values pre vs post TAVI. C-D-E: Impact of TAVI on echocardiographic parameters: Box plot with median and interquartile ranges of left ventricular end diastolic volume index (LVEDVi), left ventricular ejection fraction (EF) and pulmonary artery systolic pressure (PASP) values pre vs post TAVI.

Figure 2. Kaplan-Meier curves for survival showing that AR (2-3-4+) assessed with echocardiography had the strongest association with mortality. Abstract Figure 1.  Abstract Figure 2.

Non invasive ventilation and right ventricle function in cardiogenic pulmonary edema: an echocardiographic perspective to select the "right" ventilatory support

Funding Acknowledgements

Type of funding sources: None.

Background

High-flow nasal cannulae oxygen therapy (HFNCOT) represents a better tolerated alternative to non-invasive pressure support ventilation (NIPSV) for acute cardiogenic pulmonary edema (ACPE) treatment. However, there are still few data on the effect of HFNCOT on cardiac function and hemodynamic.

Purpose

To assess and compare the effects of NIPSV and HFNCOT in ACPE setting on right ventricular (RV) systolic function and on indices of cardiac filling and output, as measured by echocardiography. 

Methods

 This is a cross-over controlled study, enrolling 15 consecutive patients admitted to our Cardiovascular Intensive Care Unit for ACPE and hypoxaemic, normo/hypocapnic acute respiratory failure, with P/F ratio < 200. Each patient received NIPSV, followed by HFNCOT. Full echocardiographic assessment and blood gas analysis (BGA) were performed 40 minutes from onset of each ventilation modality, respectively before NIPSV to HFNCOT switch and before HFNCOT interruption. In particular, RV function parameters, together with RV and atrial strain, were prospectively collected.

Results

 In spite of not significant changes in BGA, RV function was significantly improved under HFNCOT, as compared to NIPSV, as assessed by the following parameters: tricuspid annular plane excursion (TAPSE) (P = 0.001), RV S’ wave (P = 0.007), RV fractional area change (RVFAC) (P = 0.006). Strain analysis confirmed the significant improvement in RV function, with free wall global longitudinal strain (GLS) and free wall and septum GLS significantly higher under HFNCOT, as compared to NIPSV (-21% vs -18% P < 0.001, and -15% vs -19% P = 0.008, respectively,), and a significant increase in right atrial positive longitudinal strain (P < 0.001). 

Conclusions

NIPSV significantly affect RV function making more complex the management of patients presenting with ACPE. In this setting, HFNCOT represents a valuable alternative, providing similar respiratory outcomes while preserving good right ventricle performance.

P956 Prognostic role of right ventricular hypertrophy in anderson fabry disease

Background

Right ventricular hypertrophy (RVH) is a common finding in Anderson Fabry disease (AFD). In other infiltrative and storage cardiomyopathies right ventricular (RV) involvement may influence prognostic stratification. Nevertheless, the prognostic implications of right ventricle involvement in AFD have never been assessed.

Purpose

Evaluation of the prognostic significance of RVH and RV systolic function in AFD cardiomyopathy.

Methods

Forty-five AFD patients (56% male) with extensive baseline evaluation, including assessment of RVH and RV systolic function, were followed-up for an average of 44.9 ± 8.5 months. RV systolic function was assessed by standard and tissue Doppler echocardiography and quantified using RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE) and Systolic tissue Doppler velocity of the tricuspid annulus (RV Sa). Cardiovascular events were defined as new-onset atrial fibrillation, heart failure or pace-maker implantation; renal events were defined as progression to dialysis and/or renal transplantation or significant worsening of glomerular filtration rate; cerebrovascular events were defined as stroke or transient ischemic attack. The outcome was defined as the time to death or the first event in any of the above predefined categories.

Results

Fourteen patients (31.1%) presented RVH, while RV systolic function was normal in all cases. During the follow-up period, 13 patients (28.8%, 11 male) experienced major events including two deaths. Pace-maker implantation (6 cases) was the most common type of event. At univariate analysis several variables were associated with the occurrence of events, including RVH and indexes of RV systolic function. However, at multivariate analysis only proteinuria (HR:8.3, 95% CI: 2.88 to 23.87, p ˂0.001) and LV mass indexed (HR: 1.01, 95% CI: 1.00 to 1.03, p = 0.03) were independent predictors of outcome.

Conclusions

The presence and extension of RVH is not associated with outcome in AFD. Our study confirms that at variance with other infiltrative or storage cardiomyopathies, RV involvement in AFD is an innocent bystander and does not influence prognosis.

P1590 Regional differences in longitudinal strain and response to adenosine stress in patients with myocardial infarction and ST-segment elevation. Results from Extreme trial

Background

Global longitudinal strain (LS) is a sensitive marker of ischemic myocardial damage and predicts adverse left ventricular (LV) remodeling and outcome, independently of infarct size. In healthy subjects, regional LS increases from LV base to apex and enhances under physical or pharmacological stress, while in ST-elevation myocardial infarction (STEMI), response to dobutamine depends on transmurality of necrosis. It is known that coronary flow reserve during adenosine (ADN) is impaired both in ischemic and remote myocardium, but effect of ADN on strain reserve has never been investigated. Similarly, LS response to ADN in ischemic (iLS) and remote (rLS) myocardium and their relative contribution to LV function and remodeling are still unknown.

Methods

61 consecutive patients with first STEMI (26 anterior, 29 inferior, 6 lateral), treated by successful primary percutaneous coronary intervention (PCI) followed by PCI of non-culprit coronary arteries, underwent rest and stress ADN (140 mcg/kg/minutes in 90 seconds) echocardiography at discharge (7 ± 2 days after admission). LV end-diastolic volume indexed for body surface area (EDV), ejection fraction (EF) and wall motion score index (WMSI) were measured at rest, while GLS, iLS and rLS analysis was performed both at rest and during stress. Ischemic and remote myocardium was allocated, by standard LV segmentation, basing on the culprit coronary artery.

Results

Significant differences existed among anterior, inferior and lateral STEMI in median (iQr) EDV [52 (45-59) vs 45 (36-51) vs 48 (45–56) ml, respectively, p=.034 overall], EF [47 (37-58) vs 58 (53–61) vs 56 (46-60)%, respectively, p=.002 overall], WMSI [1.63 (1.38–2) vs 1.25 (1.19-1.47) vs 1.41 (1.30-1.75), respectively, p=.001 overall]. GLS differed among anterior, inferior and lateral STEMI both at rest [13.75 (11.63-16.1) vs 19.5 (17.15-22.4) vs 17.85 (17.02-19), respectively, p<.001 overall] and during ADN [14 (12.35-16.15) vs 19.5 (17.9–22.05) vs 15.95 (14.40-19.48), respectively, p<.001], but did not change within groups. No differences were found between rest and stress iLS in any group. Similarly, rLS remained unchanged in anterior and inferior STEMI, and impaired after ADN in lateral STEMI [15.90 (11.45-18) at stress vs 16.8 (15.25-19.2) at rest, p=.043]. Inferior STEMI showed better iLS than anterior STEMI both at rest [17 (15.1–19.9) vs 13.75 (11.46-16.92), respectively, p=.001] and during stress [16.2 (15–20.4) vs 14.42 (12.67-15.83), respectively, p=.001].

Conclusions

In the subacute phase of STEMI, GLS, iLS and rLS are heterogeneous and depend on infarct site. After ADN, there is no strain reserve in ischemic neither in remote myocardium. This may reflect regional differences in the response of microcirculation and myocardium to ischemia or may underlie pre-existing pathophysiological differences in the coronary circulation

Diagnostic role of echocardiography in patients admitted to the emergency room with suspect no-ST-segment elevation acute myocardial infarction

OBJECTIVE

We investigated whether echocardiography may help identify, among patients admitted with a suspect of non-ST-segment elevation acute myocardial infarction (NSTEMI), those with athero-thrombotic coronary artery disease (CAD).

PATIENTS AND METHODS

We studied consecutive patients admitted with a clinical suspect of first NSTEMI. Echocardiography was assessed within 24 hours from admission. Patients were divided into two groups, according to the results of coronary angiography: 1) patients with obstructive stenosis (≥ 50%) and/or images of thrombosis in one or more coronary arteries (CAD group); 2) patients with no evidence of obstructive coronary arteries (NOCAD group).

RESULTS

Of 101 patients enrolled in the study, 53 (52.5%) showed obstructive CAD and 48 (47.5%) NOCAD. At echocardiographic examination, regional wall motion abnormalities were found in 52.8% of patients in the CAD group and 43.7% in the NOCAD group (p=0.43). Left ventricle ejection fraction was 56.4±6.8 vs. 54.7±9.8% (p=0.30) and wall motion score index was 1.16±0.26 vs. 1.21±0.32 (p=0.39) in the two groups, respectively. A multivariable logistic regression independent predictors of obstructive CAD included age, male gender, typical angina, diabetes and hypertension.

CONCLUSIONS

Our data showed that, in patients with acute chest pain and increased serum troponin T concentration, routine standard echocardiography does not significantly improve the diagnostic accuracy for the presence of obstructive CAD.

Hypoallergenic variants of the Parietaria judaica major allergen Par j 1: a member of the non-specific lipid transfer protein plant family

BACKGROUND

Par j 1 represents a major allergenic component of Parietaria judaica (Pj) pollen, since it is able to induce an immunoglobulin E (IgE) response in 95% of Pj-allergic patients. It belongs to the non-specific lipid transfer protein family, sharing with them a common three-dimensional structure.

METHODS

Disulphide bond variants of the recombinant Par j 1 (rPar j 1) allergen were generated by site-directed mutagenesis, and the immunological activity of rPar j 1 and its conformational mutants was compared with the use of the skin prick test (SPT). The ability to bind IgE antibodies was evaluated by Western blot, ELISA and ELISA inhibition. T cell reactivity was measured by peripheral blood mononuclear cell proliferation assay.

RESULTS

The disruption of Cys14-Cys29 and Cys30-Cys75 bridging (PjA mutant) caused the loss of the majority of specific IgE-binding activity. Additional disruption of the Cys4-Cys52 bridge (PjC mutant) and the latter Cys50-Cys91 bridge (PjD mutant) led to the abolition of IgE-binding activity. On the SPT, PjB (lacking the Cys4-Cys52 and Cys50-Cys91 bridges) was still capable of triggering a type I hypersensitive reaction in 9 out of 10 patients, and PjA in 3 out of 10 patients, while PjC and PjD did not show any SPT reactivity. All the mutants preserved their T cell reactivity.

CONCLUSION

Recombinant hypoallergenic variants of the rPar j 1 allergen described herein may represent a useful tool for improved immunotherapy.

The IgE-binding epitopes of rPar j 2, a major allergen of Parietaria judaica pollen, are heterogeneously recognized among allergic subjects

Pollen allergens are multivalent proteins that cross-link IgE antibodies on mast or basophil cells, inducing secretion of biologic mediators, and resulting in various allergic symptoms. The IgE-binding regions of the Parietaria judaica (Pj) pollen major allergen rPar j 2 were investigated. Twenty-nine single sera from Pj-allergic subjects were tested by Western blot against five recombinant peptides. At least four putative IgE-binding epitopes were identified. The analysis of their diffusion suggested a heterogeneous IgE-binding response. In fact, 75% of the sera reacted with peptide 1-54, 48% with peptide 48-101, 24% with peptide 1-30, 7% with peptide 29-54, and none with peptide 48-76. These five peptides were analyzed with the histamine-release assay. Only peptide 48-101 was capable of inducing degranulation and release of histamine. These results suggest that the recombinant rPar j 2 allergen contains IgE epitopes that are heterogeneously recognized by sensitive patients, and that therefore the therapeutic approach based on the use of haptenic peptides needs a careful evaluation.

Isolation and characterization of two cDNA clones coding for isoforms of the Parietaria judaica major allergen Par j 1.0101

Two cDNA clones named P9* and P1* of 794 and 631 bp, respectively, were isolated from a lambda ZAP cDNA expression library using Parietaria judaica (Pj) pollen-specific IgE antibodies from a pool of sera (n = 23) of patients allergic to Pj. Sequence analysis showed open reading frames of 176 and 138 amino acids. Both clones contain a putative signal peptide giving two mature processed proteins named Par j 1.0102 of 14,726 D and Par j 1.0201 of 10,677 D. These proteins represent isoallergenic forms of the major Pj allergen Par j 1.0101 (clone P5) previously reported. The Par j 1.0102 shared 98% amino acid sequence homology with the P5, while the Par j 1.0201 shared 89% homology. Since P1, P5 and P9 clones were expressed in Escherichia coli, and since the three allergenic proteins shared a very high degree of sequence identity and comparable binding to the Pj-specific IgE, we decided to analyze in more detail the immunological properties of only one allergen, the recombinant Par j 1.0101. The allergenic activity determined by the histamine release assay ranged between 9 and 56%, depending on the allergic patient analyzed, while it blocked approximately 40% of all the Pj-specific IgE antibodies, as detected after ELISA and cross-absorption analysis.

cDNA cloning, sequence analysis and allergological characterization of Par j 2.0101, a new major allergen of the Parietaria judaica pollen

A clone (P2) coding for an allergen of Parietaria judaica (Pj) pollen has been isolated and sequenced from a cDNA library in lambda ZAP using a pool of 23 sera from Pj-allergic patients. The clone contained an insert of 622 nucleotides with an open reading frame of 133 amino acids (aa) and a putative signal peptide of 31 aa giving a deduced mature processed protein of 102 aa with a molecular mass of 11344 Da. The expressed recombinant protein, named rPar j 2.0101, was a major allergen since it reacted with IgE of 82% (23/28) of the sera of Pj-allergic subjects analyzed. It was shown to be a new allergen since (i) the amino acid sequence homology with the already reported recombinant allergen Par j 1.0101 was 45% and (ii) there was no cross-inhibition between rPar j 2.0101 and rPar j 1.0101. In addition, rPar j 2.0101 inhibited 35% of the specific IgE for 10-14 kDa native allergens and preincubation of sera from Pj-allergic patients with both rPar j 2.0101 and rPar j 1.0101 fully abolished the IgE recognition of the 10-14 kDa native allergen region, suggesting that these two allergens contributed to the region.

Isolation of proteins and nucleic acids by electrophoresis on disposable gel columns

A simple and cheap one-step method to isolate proteins or nucleic acids by electrophoresis in disposable gel columns is reported. A disposable syringe was modified to host a gel column and an elution chamber. Starting from a crude extract of E. coli, the laboratory-made devise allowed the isolation of the maltose binding protein (MBP) fused to a recombinant allergenic molecule with a molecular mass of 58 kDa, from a mixture of several proteins. Also, plasmid DNA could be isolated from a mixture containing chromosomal DNA and RNA, avoiding the use of organic solvents. Electrophoresis was performed at 150 V, 35 degrees C, pH 8.0 and 8.3 for protein and DNA, respectively. The protein or the DNA obtained showed a yield of 80% and a purity grade of 90%, as estimated by densitometry.

Influence of spontaneous and surgical menopause on atherogenic metabolic risk

We evaluated serum total-, LDL-, HDL-, cholesterol and triglycerides in 858 women. Sixty-seven were in premenopause, 307 in perimenopause, 326 in spontaneous menopause, and 158 women underwent hysterectomy. Of these, 101 had bilateral ovariectomy, 24 with unilateral ovariectomy and 33 with retention of both ovaries. After correcting for chronological age and body mass index by variance analysis, it was found that total-, LDL- and HDL-cholesterol significantly increased during menopause without changes in the total cholesterol/HDL-cholesterol, LDL-cholesterol/HDL-cholesterol and triglycerides/HDL-cholesterol ratio. The changes gradually occurred during the months preceding spontaneous cessation of menses. Atherogenic metabolic risk (as relative risk of high total and LDL-cholesterol, estimated by logistic regression analysis) significantly increased in all groups of women in reference to premenopause. The risk observed in surgical menopause with bilateral ovariectomy was higher than in spontaneous menopause, and conservation of ovaries in hysterectomized women seems to protect only partially against such an increase.

Purification of Parj I, a major allergen from Parietaria, judaica pollen

A major allergen, the Parj I, was purified to homogeneity from Parietaria judaica pollen by means of ultrafiltration dialysis, preparative polyacrylamide gel chromatography and affinity chromatography through a column of Sepharose-monoclonal antibody specific for Parj I. The homogeneity of the Parj I was assessed by one single arc of immunoprecipitation both in cross immunoelectrophoresis (CIE) and crossed radioimmunoelectrophoresis, by one single band of radiostaining after a sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transfer to nitrocellulose and by one single peak after a size exclusion chromatography on high-performance liquid chromatography (HPLC). The homogeneity was further supported by crossed Laurell immunoelectrophoretic analysis, in that only one arc of precipitation was magnified in CIE after addition of the purified allergen. The purified Parj I allergen was capable of interacting in vitro with 70% of the human IgE specific for a crude P. judaica extract, as determined by radioallergosorbent test inhibition. The purified Parj I was capable of inducing positive reactions in vivo in skin prick tests, and of inducing release of histamine from blood containing basophils as determined by a histamine release assay. The amino acid analysis of the Parj I showed 118 amino acid residues per monomer analyzed and, among other residues, three methionine residues were detected. The molecular weight of the Parj I estimated by HPLC and amino acid composition was 26 kilodaltons.

Enzyme-linked immunosorbent assay for Brucella melitensis-associated antigens

An ELISA assay was performed to detect antigens of Brucella melitensis directly in the blood of patients affected by Brucellosis. Disposable polystyrene microtiter plates were coated with rabbit immunoglobulins anti-Brucella melitensis antigens and then incubated with sera of Brucellosis patients and sera of not infected normal subjects as a control, to standardize the conditions of the different steps of the assay. The level of the blood-containing Brucella antigen bound to the plate was measured by addition of anti-Brucella melitensis antiserum conjugated with alkaline phosphatase followed by incubation with the specific enzyme substrate. Sera from 9 Brucellosis patients not undergoing therapy were tested by this ELISA assay, and all showed values significantly higher than the control. A pool of 96 sera from normal subjects not infected with Brucella melitensis was used as a negative control. In addition, a different group of 8 sera from patients with Brucellosis undergoing therapy were also analyzed, but no difference in the ELISA value was observed between the two groups with or without therapy. The ELISA assay described in this paper could be a reproducible, sensitive and suitable test to detect Brucella-antigens in the blood of Brucellosis patients and it could be used in addition to the more common methods for a more thorough diagnosis of Brucellosis.

Immunochemical identification of antigens of Brucella melitensis by means of CRIE

A crude extract of Brucella melitensis was obtained by sonication, centrifugation and dialysis, and analyzed by quantitative immunoelectrophoresis. CIE analysis, using a high titer purified rabbit antibody anti-brucella fraction, showed that the Brucella melitensis extract contained at least 22 antigens that all moved towards the anode. The antigens of the crude extract able to interact with IgG of patients affected by brucellosis, were identified by means of CRIE using sheep 125I-anti human IgG. Fifteen sera of patients affected by brucellosis were analyzed by CRIE and three (Ag6, Ag12, Ag15) of the 22 antigens were able to bind specific human IgG to their corresponding immunoprecipitates. Ag6 was the only one present after one day of the CRIE plate exposure. After treatment of brucellosis patients with antibiotics for two weeks, the three antigens were still able to bind the specific IgG, after two months of treatment the antigens were reduced to two (Ag6, Ag15), while after ten months only one antigen (Ag6) was still able to bind specific human IgG. The brucellosis titer determined with common methods gave normal values after ten months of therapy. These results suggest that Ag6 is the most important antigen specific for human IgG. A preliminary determination of the molecular weight range of these antigens was carried out by a combination of size exclusion chromatography and CIE analysis. The Kav values were all above 66 kD.

Identification of a DNA polymerase beta-like form in Drosophila melanogaster adult flies

DNA polymerase beta is widely distributed in the eukariotes. So far, few examples are known in which a DNA polymerase alpha -like form alone is reported. Surprisingly, DNA polymerase beta was not detected in Drosophila embryos, while it is present in the cells of multicellular species from sponge to mammals. In view of the relevance of Drosophila as a model biological system for studying the role of the various DNA metabolism enzymes in vivo we have reinvestigated the presence of the DNA polymerase beta-like form in Drosophila adult flies. Here we report the occurrence in Drosophila melanogaster adult flies of a DNA polymerase activity that, for its NEM(1) resistance, template specificity, sensitivity to ddTTP, sedimentation coefficient and nuclear localization can be classified as a beta-like form.

DNA-dependent DNA polymerase species in male germ cells of the mouse

Quasi-homogeneous fractions of male mouse germ cells at definite stages of meiosis and spermiogenesis were obtained by using a separation method based on sedimentation velocity in an albumin gradient. In the various cell types, the total DNA-dependent DNA polymerase activity was determined, and the major enzymatic forms were characterized. The DNA polymerase species present in premeiotic, meiotic and post-meiotic cells were analyzed by glycerol gradient sedimentation. Two types of DNA polymerase were identified in fractions enriched in spermatogonia and preleptotene spermatocytes. One showed a sedimentation coefficient of about 7.5 S and was sensitive to N-ethylmaleimide (NEM); the other exhibited a sedimentation coefficient between 3 and 4 S and was resistant to NEM. On the basis of their sedimentation coefficients, their sensitivity to NEM and their template specificities, these 2 enzymes were identified respectively as alpha and beta DNA polymerases as reported in mammals. The gradient analysis performed on fractions enriched in meiotic and post-meiotic cells revealed the presence of DNA polymerase beta only. A quantitative analysis showed that the activity of the DNA polymerase beta reaches a maximum at middle-late pachytene stage and then drops gradually during spermiogenesis. Although any conclusion as to the biological role of this high level of DNA polymerase activity in pachytene spermatocytes is premature, it is tempting to suggest that this enzyme is involved in meiotic recombination.

Progesterone-induced DNA polymerase activity in full-grown oocytes of Xenopus laevis (1)

DNA polymerase activity increases in full-grown oocytes of Xenopus laevis during in vitro progesterone-induced maturation. This increase is inhibited by cycloheximide. The presence of the oocyte's nucleus (germinal vesicle) seems essential for the induction of this increase: in previously enucleated oocytes, the level of DNA polymerase activity does not change during progesterone treatment. Furthermore, a new form of DNA polymerase is detectable by DEAE chromatography in in vitro matured oocytes.

Multiple forms of DNA-dependent DNA polymerase during early development and in somatic cells of Xenopus laevis

Four distinct DNA-dependent DNA polymerase activities (DNA polymerases I, II, III and IV according to the order of elution from a DEAE column) have been separated from extracts of unfertilized Xenopus laevis eggs. The same activities, on the basis of their chromatographic properties, template specificities and sedimentation coefficients, have been found in embryos at least until the gastrula stage. On the other hand, Xenopus kidney cells grown in culture, as well as full grown oocytes lack DNA polymerase I. These data suggest the DNA polymerase I might be a special DNA polymerase activity involved in the extremely rapid DNA synthesis which takes place during early development of X. laevis.