Lipoprotein(a), type 2 diabetes and vascular risk in coronary patients

BACKGROUND: Lipoprotein(a) [Lp(a)] is an important cardiovascular risk factor in the general population. However, prospective data on the vascular risk conferred by Lp(a) in patients with diabetes mellitus are scarce and controversial. It is not known whether the diabetic state affects the association of Lp(a) with vascular events among coronary patients. DESIGN: We measured Lp(a) in 587 consecutive patients undergoing coronary angiography for the evaluation of coronary artery disease. The incidence of vascular events was recorded over 4 years. RESULTS: At baseline, Lp(a) was significantly lower in patients with type 2 diabetes (T2DM) (n = 136) than in nondiabetic individuals (11 (0.8-30) mg dL(-1) vs. 16 (0.8-51) mg dL(-1); P = 0.025). Prospectively, Lp(a) was a strong and independent predictor of vascular events in nondiabetic patients (standardized adjusted hazard ratio (HR) = 1.461 (1.121-1.904); P = 0.005), but not in patients with T2DM [HR = 0.812 (0.539-1.223); P = 0.320]. An interaction term diabetes x Lp(a) was significant (P = 0.008), indicating that Lp(a) was a significantly stronger predictor of vascular events in nondiabetic patients than in patients with T2DM. CONCLUSIONS: Lp(a) in diabetic coronary patients is low and not associated with the incidence of vascular events. Although measurement of Lp(a) provides useful information in nondiabetic coronary patients, it is of little value in coronary patients with T2DM.     

Structure/property studies of polymeric gene delivery using a library of poly(beta-amino esters).

Here we describe the synthesis and characterization of a library of 486 second-generation poly(beta-amino esters). To understand better the structure/property relationships governing polymeric gene delivery, we synthesized polymers with 70 different primary structures, at 6 to 12 different molecular weights, using monomers previously identified as common to effective gene delivery polymers. This library was characterized by (1) molecular weight, (2) particle size upon complexation with DNA, (3) surface charge upon complexation with DNA, (4) optimal polymer/DNA ratio, and (5) transfection efficiency. In this library, polymers with 20 of the 70 primary structures possess transfection efficiencies as good as or better than one of the best commercially available lipid reagents, Lipofectamine 2000. In general, the most effective polymers condense DNA into sub-150-nm complexes with positive surface charge. Among this group, the 2 most effective polymers condensed DNA to the smallest particle sizes (71 and 79 nm). Interestingly, the top 9 polymers were all formed from amino alcohols, and the structure of the 3 top performing polymers differs by only one carbon. This convergence in structure of the top performing polymers suggests a common mode of action and provides a framework with which future polymers can be designed.     

C‐type natriuretic peptide slows down wound healing but promotes angiogenesis in SKH1‐hr hairless mice

C‐type natriuretic peptide (CNP) is known to increase growth rate of endothelial cells in vitro. In addition, gene transfer of CNP into ischaemic muscle was shown to induce angiogenesis. So far, no study has addressed the effect of CNP on dermal wound healing. The ear wound model in mice was used in this study. The first group was treated with dsRed‐CNP plasmid, whereas the second group was transfected with the empty dsRed‐sine plasmid, lacking sequence coding for CNP. The third group was sham operated and treated with saline to serve as second control. Wound size was measured on days 0, 1, 3, 5, 7, 9, 11 and 14. On days 7 and 14 capillary density was analysed. Wound closure rate was significantly reduced in mice treated with CNP [dsRed‐CNP 73·3 ± 3·2% versus dsRed‐sine 94·5 ± 2·4% versus saline 92·1 ± 2·4%, n = 8 per group, analysis of variance (ANOVA) P < 0·001] at day 7 postop. Capillary density was found to be significantly higher in CNP‐treated mice (dsRed‐CNP 18·7 ± 3·9 versus dsRed‐sine 12·3 ± 2·7 versus control 10·1 ± 4·7, CD31⁺ capillaries per microscope field, ANOVA P = 0·018) at day 14 postoperative. CNP significantly reduces wound closure rate in hairless mice but promotes the development of new blood vessels. A possible explanation is the dual effect of CNP, inhibiting growth of fibromyoblasts but stimulating growth of endothelial cells. Thus, CNP may serve as a therapeutic approach to diseases caused by hyperfibrosis.     

Multidirectional flow analysis by cardiovascular magnetic resonance in aneurysm development following repair of aortic coarctation

Aneurysm formation is a life-threatening complication after operative therapy in coarctation. The identification of patients at risk for the development of such secondary pathologies is of high interest and requires a detailed understanding of the link between vascular malformation and altered hemodynamics. The routine morphometric follow-up by magnetic resonance angiography is a well-established technique. However, the intrinsic sensitivity of magnetic resonance (MR) towards motion offers the possibility to additionally investigate hemodynamic consequences of morphological changes of the aorta.We demonstrate two cases of aneurysm formation 13 and 35 years after coarctation surgery based on a Waldhausen repair with a subclavian patch and a Vosschulte repair with a Dacron patch, respectively. Comprehensive flow visualization by cardiovascular MR (CMR) was performed using a flow-sensitive, 3-dimensional, and 3-directional time-resolved gradient echo sequence at 3T. Subsequent analysis included the calculation of a phase contrast MR angiography and color-coded streamline and particle trace 3D visualization. Additional quantitative evaluation provided regional physiological information on blood flow and derived vessel wall parameters such as wall shear stress and oscillatory shear index.The results highlight the individual 3D blood-flow patterns associated with the different vascular pathologies following repair of aortic coarctation. In addition to known factors predisposing for aneurysm formation after surgical repair of coarctation these findings indicate the importance of flow sensitive CMR to follow up hemodynamic changes with respect to the development of vascular disease.     

Different left ventricular relaxation parameters in isolated working rat and guinea pig hearts – Influence of preload, afterload, temperature, and isoprenaline

In isolated ejecting rat and guinea pig hearts, the sensitivity of the time constant τ of left ventricular isovolumic pressure fall, the maximum pressure fall velocity min LVdP/dt, and the relaxation time to different hemodynamic conditions, temperature, and isoprenaline were investigated. τ was obtained by fitting the isovolumic pressure fall three-parametrically to the exponential p(t) = p∞ + (p0- p∞) exp (- tτ) which was found to be superior to semilogarithmic estimation. The influence of different working conditions on the relaxation parameters was tested by a rank correlation test and quantified by calculating standardized regression coefficients. Hemodynamic conditions were altered by changing left ventricular end-diastolic pressure (increasing inflow to the heart) and peak pressure (max LVP, varying aortic outflow resistance), and by atrial pacing (variation of interbeat interval). Lusitropic sensitivity was investigated by changing temperature and by applying isoprenaline. All regression parameters were only moderately sensitive to changes in end-diastolic pressure, max LVP, or heart rate, with the exception of a considerable afterload dependence of min LVdP/dt in rat hearts. This dependence, however, can be overcome to a large extent by dividing min LVdP/dt by mean aortic pressure. Isoprenaline strongly influenced all relaxation parameters, and so did temperature, except for relaxation time in guinea pig hearts. We conclude that τ serves as a reliable relaxation parameter, also in the hearts of small animals with heart rates up to 450 beats/min. In isolated hearts, min LVdP/dt, corrected for afterload dependence, is also suitable as a complementary index of the early relaxation phase.     

In an animal model nephrogenic systemic fibrosis cannot be induced by intraperitoneal injection of high-dose gadolinium based contrast agents

Aim and objective

Nephrogenic systemic fibrosis (NSF) has been reported in humans to be most likely induced by gadolinium based contrast agents (GBCA), namely by gadodiamide, gadopentetate dimeglumine, and gadoversetamide, rarely by other GBCA. The pathogenesis of NSF remains unclear; different hypotheses are under discussion. The objective of the study is to assess if in the animal model human-like NSF changes can be induced by high-dose, intraperitoneal GBCA injections over four weeks.

Materials and methods

After approval by the institutional animal ethics committee, six rats each were randomly assigned to groups, and treated with seven different GBCA. Intraperitoneal (IP) injections – proven in the animal model to be effective – were chosen to prolong the animals’ exposure to the respective GBCA. GBCA doses of previous intravenous (IV) animal studies were applied. After five weeks all rats were sacrificed. Sham controls were treated with IP saline injections, employing the same regimen.

Results

No findings comparable with human NSF were observed in all animals after IP treatment with all seven GBCA at daily doses of 2.5 and 5.0 mmol/kg body weight (BW). No histopathological abnormalities of all examined organs were noted. Weight loss was stated in weeks three and four with GBCA injections at doses of 5.0 mmol/kg BW, but rats regained weight after cessation of GBCA treatment.

Conclusions

NSF-comparable pathological findings could not be induced by high dose intraperitoneal injection of seven GBCA.     

Biochemical energetics of simulated platelet plug formation: Effect of thrombin, adenosine diphosphate, and epinephrine on intra- and extracellular adenine nucleotide kinetics

Washed human platelets were incubated in a modified Ringer's solution, pH 7.1, at 37 degrees C for 1 hr. Intracellular basal levels for glycogen, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), and orthophosphate were 31.1, 2.52, 1.39, 0.36, and 1.2 mumoles/ml of platelets, respectively. Extracellular ATP, ADP, and AMP remained fairly constant and represented 4, 2, and 4% of total adenine nucleotide content. Total adenine nucleotide content remained unchanged during the period of control incubation. Glycogen depletion was 17.8 mumoles/ml at the end of 1 hr; lactate production was 20.7 mumoles/ml per hr. In the presence of glucose, lactate production increased 100%, and glycogen depletion was spared 13%. Approximately 55% of glucose or glycogen fuel was converted to lactate.The agglutinating agents, thrombin, ADP, and epinephrine, resulted in increased glycogen depletion and lactate production both in the presence and absence of glucose. The effect of thrombin was greater than epinephrine. The effect of epinephrine was greater than ADP. All three agglutinating agents resulted in loss of high energy phosphates (net decline in adenine nucleotides) with release of adenine nucleotides into the extracellular environment. The effect of thrombin was greater than ADP. The effect of ADP was greater than epinephrine. In experiments with ADP addition, significant quantities of ADP were converted to AMP extracellularly. In experiments with thrombin and epinephrine appreciable quantities of extracellular orthophosphate were taken up by plateletes and could not be accounted for by changes in intracellular orthophosphate or adenine nucleotide. Sufficient ADP was released during exposure to thrombin and epinephrine to account for platelet agglutination. Changes in intracellular adenine nucleotides and orthophosphate could be correlated with the activation of regulator glycogenolytic and glycolytic enzymes.     

Successful Treatment of Renal Failure Caused by Multiple Myeloma With HLA-Identical Living Kidney and Bone Marrow Transplantation: A Case Report

Here we have described a successful HLA-identical living allogeneic kidney transplantation after bone marrow transplantation in a patient with end-stag liver disease caused by multiple myeloma (MM). Our case is unique, because this combined transplantation is rarely possible and because of our unique immunosuppressive and management strategies. A 45-year-old man with ESRD MM and κ light-chain nephropathy was diagnosed. Cytostatic treatment resulted in partial remission, so autologous peripheral stem cell transplantation (SCT) was performed leading to a complete remission; however the patient remained anuric. The patient's HLA-identical brother offered to be a donor of peripheral stem cells for collection and cryopreservation. Kidney transplantation was performed with a combination of tacrolimus sirolimuns, and methylprednisolone. With a well-functioning kidney graft, allogeneic SCT was performed in the incipient relapse phase of MM, after total body irradiation. Severe oropharyngeal infections, diarrhea, sepsis, and renal failure. Fearing acute renal rejection, we administered steroid bolus. He experienced therapy with gradual restoration of kidney function. Then, steroid-responsive acute graft-versus-host disease (grade II, predominantly bowel) was diagnosed on the background of diarrhea, which returned once. Later he experienced a left subclavian vein thrombosis at the site of a central venous catheter and sepsis. Having recovered from these events, the patient enjoys good health, with stable kidney function and normal protein excretion. After the steroid was stopped, a bone marrow biopsy revealed full-donor type normocellular hemopoiesis. Because of the chimerism, we gradually discontinued the immunosuppression including, sirolimus and finally tacrolimus, since with minimal trough levels there were no complications. Bone marrow biopsy showed a complete remission. In MM with ESRD HLA-identical combined kidney and bone marrow transplantation from a living donor may offer not only complete remission and good renal function, but also good health without immunosuppression.     

Tumor-specific targeting of pancreatic cancer with Shiga toxin B-subunit

Pancreatic carcinoma is one of the most aggressive tumor entities, and standard chemotherapy provides only modest benefit. Therefore, specific targeting of pancreatic cancer for early diagnosis and therapeutic intervention is of great interest. We have previously shown that the cellular receptor for Shiga toxin B (STxB), the glycosphingolipid globotriaosylceramide (Gb(3) or CD77) is strongly increased in colorectal adenocarcinoma and their metastases. Here, we report an upregulation of Gb(3) in pancreatic adenocarcinoma (21 of 27 cases) as compared with matched normal tissue (n = 27). The mean expression was highly significantly increased from 30 ± 16 ng Gb(3)/mg tissue in normal pancreas to 61 ± 41 ng Gb(3)/mg tissue (mean ± SD, P = 0.0006), as evidenced by thin layer chromatography. Upregulation of Gb(3) levels did not depend on tumor stage or grading and showed no correlation with clinical outcome. Tumor cells and endothelial cells were identified as the source of increased Gb(3) expression by immunocytochemistry. Pancreatic cancer cell lines showed rapid intracellular uptake of STxB to the Golgi apparatus, following the retrograde pathway. The therapeutic application of STxB was tested by specific delivery of covalently coupled SN38, an active metabolite of the topoisomerase I inhibitor irinotecan. The cytotoxic effect of the STxB-SN38 compound in pancreatic cancer cell lines was increased more than 100-fold compared with irinotecan. Moreover, this effect was effectively blocked by competing incubation with nonlabeled STxB, showing the specificity of the targeting. Thus, STxB constitutes a promising new tool for specific targeting of pancreatic cancer.