Low-density lipoprotein particle size decreases during normal pregnancy in association with triglyceride increases

OBJECTIVE: To characterize the changes in low-density lipoprotein (LDL) peak particle diameter (diameter of the predominant LDL subclass) in relation to changes in serum triglyceride concentration during successive stages of normal gestation and postpartum. METHODS: Nonfasting venous blood was obtained longitudinally during and after uncomplicated primiparous pregnancy from 10 nonsmoking women with no history of metabolic disorders. Plasma LDL diameter was determined by nondenaturing polyacrylamide gel electrophoresis. Serum concentrations of total cholesterol, triglyceride, apolipoprotein B, apolipoprotein A-I, and LDL-cholesterol were measured. Gestational changes were analyzed by one-way repeated-measures analysis of variance and the paired multiple comparison Student-Newman-Keuls test. Pearson coefficients were computed for correlation of serum lipids and LDL diameter. RESULTS: Low-density lipoprotein diameter decreased progressively with advancing gestation, evident by 16-20 weeks relative to 5-12 weeks. Seven of 10 cases were subclass pattern B (diameter less than 255 A) by term, indicating that small, dense particles predominated. The average diameter decrease from early to late gestation was 13 A. All subjects reverted to subclass pattern A (diameter 255 A or more) by 6-12 weeks postpartum, indicating prevalence of large, buoyant LDL. Low-density lipoprotein diameter correlated inversely with concentrations of serum triglyceride (r = -.61, P < .0001), apo B (r = -.66, P < .0001), cholesterol (r = -.53, P < .001), LDL cholesterol (r = -.45, P < .005), and apo A-I (r = -.39, P < .02). CONCLUSION: Gestational triglyceride increases are accompanied by progressive decreases in LDL diameter in a majority of cases. These changes undergo reversal postpartum and therefore are transient. Small, dense LDL particles have a number of properties capable of altering vascular function. However, the consequences of the gestational LDL size decrease for maternal and fetal metabolism remain unknown.     

Human apolipoprotein A-I gene promoter mutation influences plasma low density lipoprotein cholesterol response to dietary fat saturation

Numerous studies have demonstrated an association between polycyclic aromatic hydrocarbons (PAHs) and lymphocyte toxicity. The present study shows that, consistent with its effects on Ca2+ homeostasis, benzo[a]pyrene (BaP) induces apoptosis in Daudi cells. Terminal deoxynucleotidal transferase-mediated dUTP-biotin nick end labeling (TUNEL) analysis at 18 h revealed a significant increase in the number of cells undergoing apoptosis in response to BaP (75%), BaP-7, 8-dihydrodiol (110%), and BaP-7,8-9,10-diol epoxide (BPDE) (215%) over DMSO vehicle control cultures. By 36 h, the trend toward increasing numbers of apoptotic cells continued with the parent compound producing a 125% increase over control values and the 7, 8-dihydrodiol and BPDE metabolites producing 195% and 370% increases over controls, respectively. DNA fragmentation assays demonstrated the presence of internucleosomal cleavage products consistent with the increasing numbers of TUNEL-positive cells responding to PAHs at 18 and 36 h. Analysis of poly(ADP-ribose) polymerase (PARP) protein in BaP- and BaP-7,8-dihydrodiol-treated cells strongly suggested the involvement of cysteine proteases by the appearance of an 85-kD fragment derived from hydrolytic cleavage of PARP, a phenomenon that has been associated with apoptosis in many systems. Immunoblot analysis demonstrated that both BaP and its 7,8-dihydrodiol metabolite affected a pathway involving Bcl-2 and Bax cytosolic proteins. Daudi cells undergoing apoptosis at 36 h in response to 10 microM BaP, the parent compound, expressed moderately reduced amounts of Bcl-2 (78% of vehicle controls). At the same time point, the 7,8-dihydrodiol and BDPE metabolites at 3 microM resulted in Bcl-2 protein expression that was 52% of that seen in vehicle controls. Parallel samples analyzed for expression of Bax protein displayed a 130% increase over vehicle control in Bax expression in response to the parent compound, while the 7,8-dihydrodiol metabolite produced a 257% increase in Bax. Furthermore, the effects on increased Bax expression were observed as early as 3 h after PAH exposure. The apoptotic response to PAHs in Daudi cells was sensitive to 4-h pretreatment with 0.3 microM alpha-naphthoflavone (ANF), a known inhibitor of cytochrome P450. In TUNEL assays of cells exposed to PAHs following pretreatment with ANF, at 18 h there was a significant reduction in the number of cells undergoing apoptosis in response to ANF compared to cells that were not pretreated with the compound. The effect of the parent compound at 18 h was completely blocked with ANF pretreatment, while ANF exerted a relatively weaker, but significant, effect on BaP-7, 8-dihydrodiol-induced apoptosis. With regard to modulation of expression of apoptosis-related proteins, Bax expression was restored to that observed in vehicle-control cultures at all time points tested (3, 18, and 36 h). Bcl-2 expression was most responsive to ANF at later time points following PAH exposure (18 and 36 h); however, Bcl-2 appeared to be more sensitive to the effects of ANF alone. Taken together, these data suggest that modulation of Bcl-2 family proteins, perhaps secondary to altered Ca2+ homeostasis, plays an important role in human B cell apoptosis induced by BaP.     

Multiple sample PCR amplification and electrophoretic analysis on a microchip

Polymerase chain reactions (PCRs) were carried out on as many as four DNA samples at a time on a microchip device. The PCR products were then analyzed, either individually or together on the same device, by microchip gel electrophoresis. A standard PCR protocol was used to amplify 199- and 500-base pair (bp) regions of bacteriophage lambda DNA and 346- and 410-bp regions of E. coli genomic and plasmid DNAs, respectively. Thermal lysis of the bacteria was integrated into the PCR cycle. A product sizing medium, poly(dimethylacrylamide), and an intercalating dye for fluorescence detection were used in the electrophoretic analysis of the products. PCR product sizes were determined by coelectrophoresis with marker DNA.     

cDNA of eight nuclear encoded subunits of NADH:ubiquinone oxidoreductase: human complex I cDNA characterization completed

Brief elevation in postsynaptic calcium in hippocampal CA1 neurons leads to prolonged changes in synaptic strength. The calcium may enter the postsynaptic neuron via different routes, such as voltage-gated calcium channels or glutamate receptor channels of N-methyl-D-aspartate type, and/or be released from intracellular stores. The manner in which the synapse is altered, leading to the expression of an enhanced/depressed synaptic strength, is still unclear. The present study, performed using whole-cell recording from CA1 pyramidal cells of three- to five-week-old guinea-pigs, shows that postsynaptic depolarization alone, allowing for calcium influx through voltage-gated calcium channels, leads to a synaptic potentiation characterized by an altered time-course of the evoked excitatory synaptic response, an unaltered coefficient of variation of that response and a decreased paired-pulse facilitation likely related to a postsynaptic mechanism. These characteristics contrasted with those of long-term potentiation induced via activation of N-methyl-D-aspartate receptor channels, where the time-course was unaltered, the coefficient of variation was decreased and no change in paired-pulse facilitation was observed. Synapses can thus have mechanistically separate, but co-existent, potentiations of synaptic transmission initiated from separate sources for postsynaptic calcium.     

Infections due to sandfly fever virus serotype Toscana in Spain

Of the sandfly fever viruses known to be human pathogens (serotypes Toscana [TOS], Sicilian [SFS], and Naples [SFN]), only TOS has demonstrated neurotropic activity. Infections by TOS have been reported in Mediterranean countries, but the virus was previously isolated only in Italy and Portugal. We isolated 15 strains of TOS between 1988 and 1996 from the cerebrospinal fluid of patients with acute aseptic meningitis in Granada, Spain. This finding led us to study the presence of antibodies to TOS, SFS, and SFN in 1,181 adults and 87 children from different regions of Spain. We found that the prevalence of antibodies to these viruses was 26.2%, 2.2, and 11.9%, respectively; these rates imply that TOS infections are common in Spain.     

Inhibition of mitogen-activated protein kinase kinase blocks T cell proliferation but does not induce or prevent anergy

Three mitogen-activated protein kinase pathways are up-regulated during the activation of T lymphocytes, the extracellular signal-regulated kinase (ERK), Jun NH2-terminal kinase, and p38 mitogen-activated protein kinase pathways. To examine the effects of blocking the ERK pathway on T cell activation, we used the inhibitor U0126, which has been shown to specifically block mitogen-activated protein kinase/ERK kinase (MEK), the kinase upstream of ERK. This compound inhibited T cell proliferation in response to antigenic stimulation or cross-linked anti-CD3 plus anti-CD28 Abs, but had no effect on IL-2-induced proliferation. The block in T cell proliferation was mediated by down-regulating IL-2 mRNA levels. Blocking Ag-induced proliferation by inhibiting MEK did not induce anergy, unlike treatments that block entry into the cell cycle following antigenic stimulation. Surprisingly, induction of anergy in T cells exposed to TCR cross-linking in the absence of costimulation was also not affected by blocking MEK, unlike cyclosporin A treatment that blocks anergy induction. These results suggest that inhibition of MEK prevents T cell proliferation in the short term, but does not cause any long-term effects on either T cell activation or induction of anergy. These findings may help determine the viability of using mitogen-activated protein kinase inhibitors as immune suppressants.     

EMT defibrillation does not increase survival from sudden cardiac death in a two-tiered urban-suburban EMS system

BACKGROUND: The aim of this article was to analyze the perioperative mortality and stroke risk rates and late benefits of carotid endarterectomy (CE) contralateral to an occluded internal carotid artery (ICA), on the basis of our surgical experience from July 1990 to June 1996. METHODS: In 57 (14.7%) of 336 patients undergoing 388 CEs, the contralateral ICA was occluded (group I). All operations were performed under general anesthesia with selective shunting based on electroencephalographic criteria. Shunting was used in 36 (63.1%) of 57 revascularizations in group I and 47 (14.2%) of 331 operations performed on the remaining 279 patients with patent contralateral ICAs (group II) (p < 0.001). RESULTS: Perioperative strokes occurred in two patients (3.5%) in group I and three patients (1%) in group II (difference not significant). The only perioperative death, which occurred in one patient (1.7%) in group I, was the result of a perioperative stroke; two patients (0.7%) in group II died within 30 days of operation (difference not significant). Life-table cumulative stroke-free rates at 1, 3, and 5 years were 95%, 95%, 95% in group I and 98.8%, 98.2%, and 98.2% in group II, respectively (p = 0.272). Life-table cumulative survival rates at 1, 3, and 5 years were 97.5%, 94.2%, and 78.1% in group I and 99.2%, 94.8%, and 71.7% in group II, respectively (p = 0.306). CONCLUSIONS: The results of this analysis indicate that CE contralateral to an occluded ICA can be performed with acceptable perioperative mortality and stroke risk rates and late stroke-free and survival rates comparable to those seen in patients without contralateral ICA occlusion who have undergone operation. Nevertheless, we think it is misleading to imply that the risks of operating on the two groups are the same. Moreover, because no late stroke-related death occurred in patients with contralateral ICA occlusion, it would appear that superior late stroke-free rates did not translate into a prolonged survival advantage.