Macromolecular dispersion of human plasma low-density lipoproteins in hyperlipoproteinemia.

Low-density lipoprotein (LDL) has previously been reported to exist in either a polydisperse or a monodisperse state. Using the techniques of analytical velocity sedimentation and/or equilibrium density-gradient ultracentrifugation, the macromolecular dispersion of LDL has been investigated in 139 subjects classified by their lipoprotein phenotypes as follows: 63 normal, 25 type IIA, 6 type IIB, and 45 type IV. LDL polydispersion was found in 78% of subjects with hypertriglyceridemia (type IIB or IV phenotypes), while only 9% of normotriglyceridemic subjects had polydisperse LDL. A study of LDL dispersion in two families, one with hyperpreβ-lipoproteinemia and one with combined hyperlipoproteinemia, also demonstrated the frequent association of LDL polydispersity with increased plasma very low density lipoprotein (VLDL) concentrations. LDL polydispersion results from the presence of higher molecular weight, lipid-enriched lipoproteins of the LDL class. Among hyperlipoproteinemic subjects with a type IV phenotype and with polydisperse LDL, the concentrations of these higher molecular weight subspecies of LDL appear to increase with severity of the hyperlipemia. In 6 subjects, reduction of VLDL concentration resulted in a decrease in the concentration of the higher molecular weight LDL; however, LDL remained polydisperse. By contrast, approximately one-third of subjects with hypertriglyceridemia were observed to have monodisperse LDL, even in the presence of high VLDL concentrations. This observation raises the possibility of two separate populations of subjects with hypertriglyceridemia arising from increased VLDL concentration.     

MCIP1 overexpression suppresses left ventricular remodeling and sustains cardiac function after myocardial infarction

Pathological remodeling of the left ventricle (LV) after myocardial infarction (MI) is a major cause of heart failure. Although cardiac hypertrophy after increased loading conditions has been recognized as a clinical risk factor for human heart failure, it is unknown whether post-MI hypertrophic remodeling of the myocardium is beneficial for cardiac function over time, nor which regulatory pathways play a crucial role in this process. To address these questions, transgenic (TG) mice engineered to overexpress modulatory calcineurin-interacting protein-1 (MCIP1) in the myocardium were used to achieve cardiac-specific inhibition of calcineurin activation. MCIP1-TG mice and their wild-type (WT) littermates, were subjected to MI and analyzed 4 weeks later. At 4 weeks after MI, calcineurin was activated in the LV of WT mice, which was significantly reduced in MCIP1-TG mice. WT mice displayed a 78% increase in LV mass after MI, which was reduced by 38% in MCIP1-TG mice. Echocardiography indicated marked LV dilation and loss of systolic function in WT-MI mice, whereas TG-MI mice displayed a remarkable preservation of LV geometry and contractility, a pronounced reduction in myofiber hypertrophy, collagen deposition, and beta-MHC expression compared with WT-MI mice. Together, these results reveal a protective role for MCIP1 in the post-MI heart and suggest that calcineurin is a crucial regulator of postinfarction-induced pathological LV remodeling. The improvement in functional, structural, and molecular abnormalities in MCIP1-TG mice challenges the adaptive value of post-MI hypertrophy of the remote myocardium. The full text of this article is available online at http://circres.ahajournals.org.     

The value of serologic markers in indeterminate colitis: a prospective follow-up study

BACKGROUND & AIMS: In the absence of pathognomonic markers for Crohn's disease (CD) and ulcerative colitis (UC), the diagnosis of inflammatory bowel disease depends on a compendium of clinical, radiographic, endoscopic, and histologic criteria that bears imperfect specificity to the individual disorders. In 10% of cases of colitis, no differentiation can be made between CD and UC; these patients are diagnosed with indeterminate colitis (IC). We evaluated the value of anti-Saccharomyces cerevisiae antibodies (ASCA) and perinuclear antineutrophil cytoplasmic antibodies (pANCA) to increase diagnostic accuracy in categorizing IC. METHODS: Since 1996, 97 patients with IC from 3 centers (Leuven, Lille, and Vienna) were enrolled, analyzed for pANCA and ASCA, and followed up prospectively. RESULTS: A definitive diagnosis has been reached for 31 of 97 patients (32%). In these patients, ASCA+/pANCA- correlated with CD in 8 of 10 patients, whereas ASCA-/pANCA+ correlated with UC in 7 of 11 patients. The remaining 4 cases became CD, clinically behaving as UC-like CD. Almost half of the patients (47 of 97 [48.5%]) were negative for ASCA and pANCA, and 40 remain diagnosed with IC to date. Only 7 seronegative cases (14.9%) became CD or UC compared with 48% (24 of 50) of seropositive patients (P < 0.001). CONCLUSIONS: Results so far show that ASCA+/pANCA- predicts CD in 80% of patients with IC and ASCA-/pANCA+ predicts UC in 63.6%. Interestingly, 48.5% of patients do not show antibodies against ASCA or pANCA. Most of these patients remain diagnosed with IC during their further clinical course, perhaps reflecting a distinct clinicoserological entity.     

Sequence variations in the osteoprotegerin gene promoter in patients with postmenopausal osteoporosis

Osteoprotegerin (OPG) is a recently discovered member of the TNF receptor superfamily that acts as an important paracrine regulator of bone remodeling. OPG knockout mice develop severe osteoporosis, whereas administration of OPG can prevent ovariectomy-induced bone loss. These findings implicate a role for OPG in the development of osteoporosis. In the present study, we screened the OPG gene promoter for sequence variations and examined their association with bone mineral density (BMD) in 103 osteoporotic postmenopausal women. Single-strand conformation polymorphism analysis followed by DNA sequencing revealed a presence of four nucleotide substitutions: 209 G-->A, 245 T-->G, 889 C-->T, and 950 T-->C. The frequencies of genotypes were as follows: GG (89.3%), GA (10.7%) for 209 G-->A polymorphism; TT (89.3%), TG (10.7%) for 245 T-->G polymorphism; and TT (25.2%), TC (53.4%), CC (21.4%) for 950 T-->C polymorphism. Substitution 889 C-->T was found in only two patients. Statistically significant association of genotypes with BMD at the lumbar spine (P = 0.005) was observed for 209 G-->A and 245 T-->G polymorphisms. Haplotype GATG was associated with lower BMD as compared with GGTT haplotype. Our results suggest that 209 G-->A and 245 T-->G polymorphisms in the OPG gene promoter may contribute to the genetic regulation of BMD.     

Systemic therapy in patients with node-negative breast cancer. A commentary based on two National Surgical Adjuvant Breast and Bowel Project (NSABP) clinical trials

OBJECTIVE: To determine whether in the previous National Surgical Adjuvant Breast and Bowel Project (NSABP) studies of node-negative breast cancer there were either cohorts of patients with a prognosis favorable enough to preclude using systemic therapy or subsets of patients who failed to benefit from the treatments. DESIGN: Randomized clinical trials with stratification after surgery. SETTING: NSABP trials at institutions in the United States and Canada. PATIENTS: Data were collected on 731 eligible patients (Protocol B-13) with estrogen-receptor-negative tumors who randomly received either no therapy after surgery or sequential methotrexate and fluorouracil (M----F) followed by leucovorin. Data were also collected on 2834 patients (Protocol B-14) with estrogen-receptor-positive tumors who randomly received either placebo or tamoxifen treatment. The percentage of patients surviving disease-free was determined through 4 years of follow-up using life-table estimates. INTERVENTIONS: Protocol B-13 patients received 12 courses of M----F given intravenously on days 1 and 8 every 4 weeks. Leucovorin therapy was begun 24 hours after M----F administration. Protocol B-14 patients received 5-year treatment with either tamoxifen (10 mg twice daily by mouth) or placebo. RESULTS: When the outcome of untreated patients in either trial was related to the stratification variables, women were found to have a disease-free survival of less than 80% through 4 years of follow-up. This percentage is apt to decrease because the probability of treatment failure increases with time. In both trials, all subsets of women benefited from M----F or tamoxifen therapy. CONCLUSIONS: The disease-free survival of all cohorts of node-negative patients with estrogen-receptor-negative or estrogen-receptor-positive tumors was poor enough to justify systemic treatment. The benefits of the therapies used are insufficient to eliminate the need for assessing putatively better regimens.     

A single multiplex assay to identify major malaria vectors within the African Anopheles funestus and the Oriental An. minimus groups

The African Anopheles funestus and the Oriental An. minimus groups are closely related and composed of major malaria vectors in Africa and Southeast Asia, respectively. None of the species of either the An. funestus or the An. minimus group can be identified with absolute certainty using the adult morphology. Polymorphisms present on the internal transcribed spacer 2 (ITS2) of ribosomal DNA allowed the development of 10 primers that combined with an universal forward primer lead to a simple and sensitive multiplex allele-specific polymerase chain reaction (AS-PCR). Moreover, the possible additional amplification of the entire ITS2 allows one to detect other anopheline species in sympatry with members of both groups not included in this assay and serves as a control band. This universal PCR method permits the discrimination of 10 species within the subgenus Cellia, among which figure three major malaria vectors, and constitutes a very efficient and powerful tool to improve our knowledge on these species distribution and biology. Not only restricted to anophelines, this AS-PCR could also be developed and applied to other insect groups.     

"Hydrophobic" surfactant apoproteins and augmentation of phospholipid recycling

A 10,000-11,000 molecular weight apoprotein was isolated from an ethanol-ether extract of rat lung surfactant and purified by silicic acid chromatography. The protein (Apo Et) significantly augmented the uptake of phospholipids in liposomal form by cultured rat granular pneumocytes by a time-dependent process that varied with protein concentration and liposome composition. The protein had no effect on cell viability and showed no phospholipase activity. The mechanism for this augmented phospholipid uptake is not known but could be due to an alteration of physical form of the phospholipids by the protein or to a receptor-mediated uptake of phospholipids. This protein may prove to be a physiologically important regulator of the recycling of lung surfactant phospholipids.     

Stimulation and homologous desensitization of calcitonin gene-related peptide receptors in cultured beating rat heart cells

Addition of calcitonin gene-related peptide (CGRP), 1 X 10(-7) M, to cultured neonatal rat heart cells resulted in rapid increases in beating rate and cellular concentrations of cAMP. Calcitonin (1 X 10(-7) M), in contrast, had no significant effect on heart cell beating rate or cAMP content. CGRP-stimulated increases in heart cell cAMP content were rapid, transient, dose dependent, and potentiated by isobutyl-methylxanthine (1 X 10(-4) M). Half-maximal increases in heart cell cAMP content occurred at 1 X 10(-8) M CGRP. Heart cell adenylate cyclase responses to CGRP were desensitized in a rapid (i.e. within 5 min) and dose-dependent manner by prior exposure to CGRP. Complete and half-maximal desensitization of heart cells to CGRP occurred at 1 X 10(-8) and 3 X 10(-10) M CGRP, respectively. Desensitization of heart cells to CGRP did not modify the cAMP response of heart cells to beta-adrenergic agonist stimulation, and beta-adrenergic agonist desensitization of heart cells did not modify responses to CGRP. Heart cell cAMP responses to CGRP were additive to those of the beta-adrenergic agonist isoproterenol and occurred in the presence of beta-adrenergic blockade. These observations demonstrate that CGRP exerts specific and potent agonist actions in cardiac myocytes and that regulation of myocardial responses to CGRP may occur by mechanisms involving increases in cAMP and receptor desensitization.