Calcification of coronary arteries: detection and quantification with double-helix CT

PURPOSE

To evaluate the accuracy of double-helix computed tomography (CT) in coronary artery calcification detection and quantification.

MATERIALS AND METHODS

One hundred sixty patients with coronary disease (135 men, 25 women; age range, 45-62 years), of whom 138 had obstructive (stenosis of > 50% of diameter; n = 129) or mild (< 50% stenosis; n = 9) coronary artery disease (CAD) and 22 had normal coronary arteries (per angiographic findings), and 56 age-matched healthy control subjects underwent double-helix CT.

RESULTS

Double-helix CT findings indicated that calcification was significantly more prevalent in patients with CAD (> 83%) than in patients with normal coronary arteries (27%) or in healthy control subjects (34%; P < .01). Sensitivity in detecting obstructive CAD was high (91%); however, specificity was low (52%) because of calcification in nonobstructive lesions. Comparison of double-helix CT and angiographic findings indicated that double-helix CT was 84% accurate with positive and negative predictive values of 89% and 59%, respectively.

CONCLUSION

Double-helix CT is a useful noninvasive method for detection and quantification of coronary artery calcification.

Q wave and Non-Q wave myocardial infarction after thrombolysis

OBJECTIVES

We studied the clinical outcome of Q wave and non-Q wave infarction after thrombolytic therapy.

BACKGROUND

Controversy exists over the clinical significance of Q waves after thrombolysis.

METHODS

We studied postthrombolytic angiographic results and short- and long-term clinical outcome in 150 patients with acute myocardial infarction classified as Q wave and non-Q wave on the 24-h and discharge electrocardiograms (ECGs). The results from the two groups were then compared.

RESULTS

Eighty percent of patients had a Q wave and 20% a non-Q wave infarction on the 24-h ECG. The latter patients had lower peak creatine kinase (CK) levels (p < 0.001), but the two groups did not differ significantly otherwise. In 18 patients with a Q wave infarction on the 24-h ECG, pathologic Q waves disappeared. However, in seven patients with a non-Q wave infarction on the 24-h ECG, pathologic Q waves appeared throughout the hospital period. Q wave regression was associated with lower peak CK levels (p < 0.001) and an improvement in left ventricular ejection fraction (p < 0.01). Thus, only 72% of patients had a Q wave and 28% a non-Q wave infarction on the discharge ECG. Patients with a non-Q wave infarction on the discharge ECG had higher patency of the infarct-related artery (p < 0.04), lower mean peak CK levels (p < 0.0001), a higher ejection fraction (p = 0.001) and a lower incidence of heart failure (p = 0.06) than patients with a Q wave infarction on the discharge ECG. Although the 2-year incidence of reinfarction and revascularization was higher in patients with a non-Q wave infarction on the discharge ECG (p < 0.05), 2-year mortality was lower (p = 0.08).

CONCLUSIONS

Although the early postthrombolytic distinction between Q wave and non-Q wave infarction conveys no significant information, during the hospital period, non-Q wave infarction is associated with a smaller infarct area, improved left ventricular function and lower mortality.

Induction of tolerance in freshly isolated alloreactive T cells by activated T cell stimulators is not due to the absence of CD28-B7 interaction

Human T cells express MHC class II molecules on activation, and this makes them potential APCs for responder CD4 T cells. We have shown earlier that MHC class II-expressing human T cell APCs induce specific tolerance in freshly isolated alloreactive responder CD4 T cells. In this study, we show that this induction of tolerance does not depend on the expression of a specific coreceptor on the stimulator T cell APCs, because both CD4 and CD8 T cell stimulators efficiently induce tolerance. Such a tolerant cell population responds significantly better to IL-2 than unprimed cells, indicating the physical presence of T cells expressing higher levels of IL-2 receptors. The addition of exogenous IL-2 during priming with activated T cell APCs effectively blocks the induction of tolerance and permits successful priming of alloreactive responder cells. We have investigated the possible role of the CD28/CTLA4-B7 family interaction in this model of induction of T cell anergy in T-T interactions. The freshly activated T cell APCs used in this study express CTLA4-binding ligand(s). Furthermore, cross-linking CD28 on responder T cells does not enable activated T cell APCs to elicit a primary proliferative alloresponse, nor does it prevent the induction of tolerance in responder T cells. The CD28/CTLA4-B7 family interaction is thus unlikely to be involved in the induction of T cell anergy by T cell APCs.

Induction of tolerance in freshly isolated alloreactive T cells by activated T cell stimulators is not due to the absence of CD28-B7 interaction

Human T cells express MHC class II molecules on activation, and this makes them potential APCs for responder CD4 T cells. We have shown earlier that MHC class II-expressing human T cell APCs induce specific tolerance in freshly isolated alloreactive responder CD4 T cells. In this study, we show that this induction of tolerance does not depend on the expression of a specific coreceptor on the stimulator T cell APCs, because both CD4 and CD8 T cell stimulators efficiently induce tolerance. Such a tolerant cell population responds significantly better to IL-2 than unprimed cells, indicating the physical presence of T cells expressing higher levels of IL-2 receptors. The addition of exogenous IL-2 during priming with activated T cell APCs effectively blocks the induction of tolerance and permits successful priming of alloreactive responder cells. We have investigated the possible role of the CD28/CTLA4-B7 family interaction in this model of induction of T cell anergy in T-T interactions. The freshly activated T cell APCs used in this study express CTLA4-binding ligand(s). Furthermore, cross-linking CD28 on responder T cells does not enable activated T cell APCs to elicit a primary proliferative alloresponse, nor does it prevent the induction of tolerance in responder T cells. The CD28/CTLA4-B7 family interaction is thus unlikely to be involved in the induction of T cell anergy by T cell APCs.

[Meralgia paraesthetica and its surgical treatment]

Compression neuropathy of the lateral femoral cutaneous nerve (meralgia paresthetica) leads to pain and dysesthesia in the anterolateral thigh. Over a period of 23 1/2 years, 29 patients (33 procedures) were operated on after failure of conservative treatment: 18 patients (20 procedures) underwent neurolysis of the nerve, and in 11 the nerve was transected. The 33 procedures were necessary because 1 patient had bilateral meralgia paresthetica and there were 3 recurrences with persisting pain. The average follow-up was 32 months after neurolysis and 87 months after transection. Complete or partial pain relief was found in 72% after decompression and in 82% after transection of the nerve.

Antimony oxidation states in antileishmanial drugs

Chemical methods specific for the determination of the levels of trivalent antimony (Sb+3) and pentavalent antimony (Sb+5) were used to investigate proprietary formulas used to treat leishmaniasis. Trivalent antimony was determined by differential pulse polarography, whereas Sb+5 was determined by iodine titration. Proprietary formulas based on N-meglumine antimoniate (Glucantime) were analyzed in detail. The results showed Sb+3 in all ampules of Glucantime. In formulations said to contain either 85 or 100 mg of Sb+5/ml, we found both forms of antimony. The amount of Sb+3 ranged from 10.5 to 15.8% (10.06-18.96 mg of Sb/ml). These findings raise issues on product stability and standardization and may help to clarify resistance to antimonial drugs and the reducing effect of tissue on Sb+5.

Modulation of immunogenicity and antigenicity of proteins by maleylation to target scavenger receptors on macrophages

We have maleylated proteins to target macrophage-specific scavenger receptors and have used this system to study changes in the epitopes and immunogenicity of such proteins. We show that maleylation of diphtheria toxoid (DT) induces targeting to macrophage scavenger receptors and enhances its immunogenicity. DT does not evoke detectable serum Ab responses upon injection as soluble protein. However, maleylated DT (mDT) does generate a significant Ab response. Furthermore, immunization with soluble mDT leads to a better T cell proliferative response in vitro than immunization with DT can generate, thereby demonstrating that maleylation leads to enhanced T cell immunogenicity in vivo. We also find that maleylation disrupts the native B cell epitopes of DT and creates new epitopes, because antisera to DT and mDT do not cross-react. At least some of the new epitopes generated are maleylation specific, because antisera against various maleylated proteins do cross-react. In contrast, maleylation does not significantly modify the repertoire of T cell epitopes generated from DT, because T cells generated by either DT or mDT immunization are cross-reactive, and both DT and mDT can stimulate T cells that are specific for single synthetic DT peptide. Maleylated proteins are better presented in vitro than are their native counterparts, and this enhancement of presentation is blocked by unrelated maleylated proteins. These results suggest that Ags targeted to scavenger receptors on macrophages by maleylation are better presented to T cells and are immunogenic in vivo without adjuvant.

Analysis of immunization route-related variation in the immune response to heat-killed Salmonella typhimurium in mice

In examinations of the factors regulating the quality and quantity of the immune response to Salmonella typhimurium, we have shown previously that live and heat-killed preparations of S. typhimurium can induce gamma interferon-dominant and interleukin-4-dominant immune responses, respectively, upon intraperitoneal (i.p.) immunization of BALB/c mice. Using this system to investigate the role of the route of immunization in the immune response, we show in the present study that i.p. immunization with heat-killed S. typhimurium generates a quantitatively better immune response than does intradermal (i.d.) immunization. The quantitative differences observed between the i.p. and i.d. routes are apparent in the amount of S. typhimurium-specific antibodies produced, the extent of responses in T-cell proliferation assays, and the quantities of lymphokines generated. However, the ratios of immunoglobulin (Ig) isotypes [IgG1/IgG2a] are comparable and the relative dominance of interleukin-4 over gamma interferon is seen in both i.p.- and i.d.-immunized mice, suggesting that the predominant T-cell effector pathways triggered are not qualitatively dependent on the route of immunization. An examination of the antigenic profile recognised by the B-cell and T-cell responses in i.p.- versus i.d.-immunized mice shows that while the Western immunoblot patterns recognized by serum antibodies from the two groups of mice were not significantly different, T cells from i.p.-immunized mice recognized a broader spectrum of antigens in an immunoblot assay than did those from i.d.-immunized mice. These data suggest that there may be a significant difference in the antigen-processing ability of peritoneal and dermal antigen-presenting cells for complex antigenic formulations such as bacterial vaccines.

Modulation of immunogenicity and antigenicity of proteins by maleylation to target scavenger receptors on macrophages

We have maleylated proteins to target macrophage-specific scavenger receptors and have used this system to study changes in the epitopes and immunogenicity of such proteins. We show that maleylation of diphtheria toxoid (DT) induces targeting to macrophage scavenger receptors and enhances its immunogenicity. DT does not evoke detectable serum Ab responses upon injection as soluble protein. However, maleylated DT (mDT) does generate a significant Ab response. Furthermore, immunization with soluble mDT leads to a better T cell proliferative response in vitro than immunization with DT can generate, thereby demonstrating that maleylation leads to enhanced T cell immunogenicity in vivo. We also find that maleylation disrupts the native B cell epitopes of DT and creates new epitopes, because antisera to DT and mDT do not cross-react. At least some of the new epitopes generated are maleylation specific, because antisera against various maleylated proteins do cross-react. In contrast, maleylation does not significantly modify the repertoire of T cell epitopes generated from DT, because T cells generated by either DT or mDT immunization are cross-reactive, and both DT and mDT can stimulate T cells that are specific for single synthetic DT peptide. Maleylated proteins are better presented in vitro than are their native counterparts, and this enhancement of presentation is blocked by unrelated maleylated proteins. These results suggest that Ags targeted to scavenger receptors on macrophages by maleylation are better presented to T cells and are immunogenic in vivo without adjuvant.

Induction of tolerance in freshly isolated alloreactive CD4+ T cells by activated T cell stimulators

Activated human T cells express major histocompatibility complex class II proteins, and their potential to present antigens to T cell clones has been documented extensively. The effect of such TT presentation on responder T cell clones has been shown to be the induction of tolerance, sometimes accompanied by activation. To investigate whether freshly isolated responder T cells are also susceptible to such induction of tolerance by activated T cells functioning as antigen-presenting cells (APC), we have used the capability of unprimed ex vivo T cells to respond in a proliferation assay in vitro to alloligands on professional APC. We show that purified human T cells ex vivo, when exposed to alloligand on activated T cells for primary allorecognition in vitro, fail to mount a proliferative response. Priming of responder CD4+ T cells with alloligand expressed on activated T cells results in the induction of nonresponsiveness to a subsequent challenge by competent allo-APC. This ability of activated, HLA-DR+ T cells to induce nonresponsiveness to subsequent challenge in bulk CD4+ T cell populations ex vivo has interesting implications for infections involving T cells such as human immunodeficiency virus.

Early T wave inversion after thrombolytic therapy predicts better coronary perfusion: clinical and angiographic study

OBJECTIVES

This study was undertaken to test the hypothesis that early inversion of T waves after thrombolytic therapy for acute myocardial infarction predicts patency of the infarct-related artery with high Thrombolysis in Myocardial Infarction (TIMI) perfusion flow and better in-hospital outcome.

BACKGROUND

Although numerous studies have demonstrated a strong association between early resolution of ST segment elevation after acute myocardial infarction and successful thrombolysis, little is known about early changes in T waves after thrombolytic therapy.

METHODS

Ninety-four consecutive patients with acute myocardial infarction treated with recombinant tissue-type plasminogen activator (rt-PA) were studied with admission and predischarge radionuclide ventriculography and with coronary angiography within 72 h of admission. Patient stratification was based on the presence or absence of early (within 24 h) T wave inversion.

RESULTS

Early T wave inversion was associated with a higher patency rate of the infarct-related artery (90% vs. 65%, p < 0.02) and less severe residual stenosis ([mean +/- SD] 73 +/- 27 vs. 83 +/- 22, p = 0.06), and when only TIMI perfusion grade 3 was considered, the difference was even greater (77% vs. 41%, p < 0.001). Patients with early inversion of T waves had a lower peak creatine kinase value ([mean +/- SD] 678 +/- 480 vs. 1,076 +/- 620, p < 0.01), and although a similar percent of patients with and without early T wave inversion had a normal ejection fraction (> or = 55%) on admission, a higher percent of patients with early inversion had a normal ejection fraction at hospital discharge (71% vs. 44%, p < 0.03). Early T wave inversion anticipated a more benign in-hospital clinical course with a lower incidence of adverse cardiac events (10% vs. 33%, p < 0.02).

CONCLUSIONS

Early inversion of T waves in patients with acute myocardial infarction treated with thrombolytic therapy suggests patency of the infarct-related artery, better perfusion grade and left ventricular function and a more benign in-hospital course.

Ligation of CD45 on B cells can facilitate production of secondary Ig isotypes

The possibility that isotype switching in B cells may be affected by engagement of the CD45 molecule on B cells has been investigated in microcultures containing limiting numbers of B cells and nonlimiting numbers of both alloreactive Th cells and purified dendritic cells (DC). Addition of Abs to the B cell-specific isoform, B220, to the microcultures leads to an increase in the proportion of B cell clones that secrete secondary Ig isotypes. In the presence of anti-CD45 Ab, microculture wells show a 39% frequency of secondary isotypes (560/1440) compared with a 11% frequency in control microcultures (89/780). Cross-linking appears to enhance this effect. Even in cultures of B cells and DC without T cells, addition of anti-B220 induces isotype switching in a significant number of microwells. Cross-linking and capping B220 molecules results in co-capping of surface Ig and MHC class II molecules. The results suggest that signal transduction through the CD45 molecule may affect pathways involved in isotype switching.

Ligation of CD45 on B cells can facilitate production of secondary Ig isotypes

The possibility that isotype switching in B cells may be affected by engagement of the CD45 molecule on B cells has been investigated in microcultures containing limiting numbers of B cells and nonlimiting numbers of both alloreactive Th cells and purified dendritic cells (DC). Addition of Abs to the B cell-specific isoform, B220, to the microcultures leads to an increase in the proportion of B cell clones that secrete secondary Ig isotypes. In the presence of anti-CD45 Ab, microculture wells show a 39% frequency of secondary isotypes (560/1440) compared with a 11% frequency in control microcultures (89/780). Cross-linking appears to enhance this effect. Even in cultures of B cells and DC without T cells, addition of anti-B220 induces isotype switching in a significant number of microwells. Cross-linking and capping B220 molecules results in co-capping of surface Ig and MHC class II molecules. The results suggest that signal transduction through the CD45 molecule may affect pathways involved in isotype switching.

Balloon aortic valvuloplasty in the elderly: useful when there is no alternative

Of 63 elderly patients with calcific aortic stenosis in whom balloon aortic valvuloplasty was performed, 26 treated with the new technique of Cribier and Letac are the subject of this report. Patients were referred for the procedure because they were at high surgical risk, or were not candidates for surgery. Seven matched patients who fit the criteria for balloon valvuloplasty but refused the valvuloplasty procedure served as controls. Aortic gradient decreased from 78 +/- 27 mm Hg to 35 +/- 20 mm Hg and aortic valve area increased from 0.47 +/- 0.16 cm2 to 0.83 +/- 0.38 cm2 (P < 0.0001). Symptomatic improvement was immediately obtained in each patient. Complications were rare, with only one patient needing vascular repair for femoral artery occlusion. Three patients died during the initial hospitalization (none during the procedure). Valvuloplasty patients were followed for a mean period of 9.6 +/- 9.4 months. Three months survival was 87%, 6 months survival was 76%, and 12 months survival was 61%. Four of seven patients in the control group (57%) died within 3 months after initial referral. Balloon aortic valvuloplasty is a useful treatment in elderly patients who are poor surgical candidates. It may have a positive influence on short-term survival.

Immunization with live versus killed Salmonella typhimurium leads to the generation of an IFN-gamma-dominant versus an IL-4-dominant immune response

The mechanisms responsible for differential commitment of effector T cells to the production of either the IL-4/5/10 group or to the IL-2/IFN-gamma group of lymphokines during an immune response have not yet been clearly elucidated. We have used Salmonella typhimurium as a model murine bacterial parasite in BALB/c mice for live-cell versus killed-cell immunization and looked at the immune response in terms of delayed type hypersensitivity (DTH), IgG subclass distribution in the serum antibody response, and antigen-specific T cell proliferation and lymphokine secretion. The results indicate that the two forms of immunogen induce qualitatively different immune responses. Intraperitoneal immunization with live bacteria induces an IFN-gamma-dominant immune response associated with a strong DTH reaction and relatively higher levels of specific antibodies belonging to the IFN-gamma-dependent IgG2a isotype rather than the IL-4-dependent IgG1 isotype. Immunization with heat-killed bacteria gives rise to an IL-4-dominated response that shows excellent proliferative capacities in vitro, with lower levels of DTH responses and comparatively high levels of specific antibodies of the IgG1 isotype. IL-2 production in the responses generated by the two modes of immunization, however, is not preferentially associated with IFN-gamma production, unlike the reported profiles of long-lived murine T cell clones in vitro.

Murine CD8+ T suppressors against mycobacterial 65-kDa antigen compete for IL-2 and show lack of major histocompatibility complex-imposed restriction specificity in antigen recognition

The mechanism of antigen-specific suppression and reasons for aberrant major histocompatibility complex (MHC) class II restriction mediated by CD8+ T cells was investigated in a previously reported murine model of immunosuppression, generated by intraperitoneal priming with Mycobacterium vaccae. Both the CD4+ T helper cells (Th) and CD8+ T suppressor cell (Ts) of M. vaccae-primed mice recognized the 65-kDa antigen of the bacillus, presented by I-A and I-E, respectively. The CD8+ Ts could inhibit non-antigen-specific proliferation of primed CD4+ T cells induced by the exogenously added interleukin (IL)-2 (concanavalin A-stimulated culture supernatant). For inhibition, the Ts had to be activated by the 65-kDa antigen. The degree of inhibition was dependent upon the amount of added IL-2 and the relative numbers of primed CD8+ and CD4+ T cells. On incubation with antigen-presenting cells, and the 65-kDa antigen, the primed CD8+ T cells absorbed IL-2 as efficiently as primed CD4+ T cells. Based on this, it was concluded that the primed CD8+ T cells induced suppression by competition for IL-2. Employing the same model, the MHC restriction of recognition of the suppressor epitope of the 65-kDa antigen by the CD8+ Ts was investigated. The epitopes presented by diverse MHC class II molecules, such as self I-A, I-E and even allogeneic I-E were similar, because they were recognized by the same population of primed CD8+ Ts. Further, immunization of C57BL/6 mice with Ltk-cells expressing H-2 DkKk alloantigens, stimulated CD8+ T cells capable of recognizing M.vaccae 65-kDa antigen. Based on these data, it was proposed that recognition of the suppressor epitope of the 65-kDa antigen by the primed CD8+ Ts exhibits lack of restriction specificity imposed by MHC diversity.

Evaluation of a new mechanical atherectomy system (TRAC) in normal canine coronary arteries. Transluminal Rotary Atherectomy System

BACKGROUND

The feasibility and safety of a new mechanical atherectomy device, the Transluminal Rotary Atherectomy System (TRAC), for coronary application was examined in vivo in eight dogs. The system operates over a standard balloon coronary guide wire and excises and removes the atherosclerotic material in a single application.

METHODS

The TRAC was introduced percutaneously using routine cardiac catheterization technique in four open-chest dogs (acute experiments) and in four closed-chest dogs (chronic experiments).

RESULTS

Coronary angiography at the end of the procedure and 1-3 days later demonstrated normal coronary arteries without evidence of dissection, perforation, spasm, or thrombus formation. Macroscopic examination revealed perivascular bleeding along the treated coronary arteries in two out of eight dogs. Microscopic examination of these arteries demonstrated minimal endothelial peeling. Histology of the other coronary arteries demonstrated normal intact blood vessels without evidence for thrombus formation.

CONCLUSIONS

These results demonstrate that it is feasible and relatively safe to introduce and operate the new TRAC mechanical atherectomy system in the normal coronary arteries of a beating dog heart.

Revision procedures for complications of surgery for osteoarthritis of the carpometacarpal joint of the thumb

Between the years 1980 to 1987, 17 patients had revision procedures for complications of surgery for osteoarthritis of the carpometacarpal joint of the thumb. 12 followed silastic implant arthroplasty, four trapeziectomy and one arthrodesis. The failed silastic arthroplasties were treated by removal of the implant, and soft tissue arthroplasty in eight, revision with another implant in three and intermetacarpal bone grafting in one. Patients with metacarpo-scaphoid arthritis after trapeziectomy were treated by silastic implant arthroplasty in three and fusion in one. Nine of the 17 revision procedures (53%) had good, three (18%) fair and five (29%) poor results respectively.

The Bard Rotary Atherectomy System (BRAS): initial experience in patients with peripheral vascular disease

Sixteen patients with a mean age of 65.4 +/- 9.8 years and suffering from peripheral vascular disease underwent peripheral atherectomy using a new mechanical device--the BARD Rotary Atherectomy System (BRAS). The BRAS is an "over the wire" system that consists of a spiral guidewire and a handheld motor drive unit, which rotates at 1,500 rpm. Prior to the procedure angiography demonstrated the presence of 18 obstructions (1 tibial, 2 popliteal, 15 superficial femoral arteries) with a mean stenosis of 95.7 +/- 8%. Successful atherectomy was achieved in 16 of 18 lesions and resulted in an 89% immediate success rate and a significant (P less than 0.01) reduction of stenosis to 37.8 +/- 12.5%. There were no significant complications. The excised and removed material embedded over the spiral guidewire demonstrated the presence of fibrotic tissue, fatty lesions, and calcium deposits. Medial or adventitial layers were not present in the removed atherosclerotic material. Mean ABI was significantly (P less than 0.01) increased from 0.38 +/- 0.17 to 0.55 +/- 0.21 following atherectomy. Angiographic follow-up obtained in ten patients 8.8 +/- 5.2 months following the procedure demonstrated restenosis in six of those ten patients. The ABI at this time remained unchanged. These results demonstrated that the new BRAS mechanical atherectomy system is feasible and safe for recanalization of severely stenosed arteries in patients with peripheral vascular disease.

T and B cell receptors discriminate major histocompatibility complex class II conformations influenced by the invariant chain

Direct recognition of major histocompatibility complex (MHC) molecules may occur when T cells are positively selected in the thymus and also during recognition of non-self MHC molecules. Since peptide recognition and binding of particular monoclonal antibodies is strongly influenced by the invariant chain (Ii) of the class II molecule, we have asked whether Ii also affects recognition of non-self MHC molecules by T cells. We find that Ii binding alters MHC class II conformation as detected by a monoclonal antibody, and that this alteration is retained in cell surface MHC class II molecules after Ii dissociates. This altered conformation also affects recognition by allogeneic T cells. Normal T cells and T cell clones preferentially recognize MHC class II molecules that have been associated with Ii, suggesting that thymic selection may be influenced by MHC conformation independently of specific peptide binding.