Nonuniform blood flow in the canine left ventricle

In order to investigate the relationship between coronary perfusion pressure and blood flow distribution in the left ventricle (LV), we measured myocardial blood flow in small regions using radioactive microspheres in six anesthetized, open-chest dogs. Mean coronary perfusion pressure (CPP) was controlled with a femoral artery to left main coronary artery shunt which included a pressurized, servo-controlled blood reservoir. In each dog, we measured flow in 192 regions of the LV free wall (mean weight per region = 206 +/- 38 mg) at different perfusion pressures. At CPP = 80 mm Hg, blood flow to individual regions varied fourfold (0.30 to 1.18 ml/min/g; relative dispersion (RD) = 21.8 +/- 2.3%). At CPP = 50 mm Hg, flow varied over sevenfold (0.08 to 0.60 ml/min/g; RD = 42.8 +/- 10%; P less than 0.01 vs 80 mm Hg). This relationship between flow variability and CPP was present within individual LV layers as well between layers and is much higher than the error associated with the microsphere technique. We conclude that blood flow to small regions of the LV is markedly nonuniform. This heterogeneity becomes more profound at lower CPP. These findings suggest that (1) global measurements of coronary flow must be interpreted with caution, and (2) even in hearts with normal coronary arteries some regions of the LV are more susceptible to ischemia than others. In addition, these findings may help explain the patchy nature of myocardial damage that occurs following periods of low coronary pressure or inadequate myocardial protection during cardiopulmonary bypass.     

Effect of total parenteral nutrition with intravenous fat on lipids and high density lipoprotein heterogeneity in neonates

Plasma lipid concentrations and high density lipoprotein (HDL) subclass distributions were evaluated in 22 newborn infants nourished with intravenous (iv)-fat. The majority of infants were premature with respiratory distress syndrome. Based on baseline (prior to iv-fat) HDL subclass profiles determined by gradient gel electrophoresis (GGE), infants fell into two classes, one with two or more pronounced peaks within the normal HDL spectrum (group I, 17 subjects) and the other with highly unusual HDL distribution (group II, five subjects). Total plasma cholesterol increased in both groups during low and high fat intravenous feeding. HDL-cholesterol, however, did not change with iv-fat where mean values for groups I and II at baseline, iv-low fat and -high fat were: group I, 31.2 +/- 7.1, 30.0 +/- 8.8, and 36.6 +/- 16.7 mg/dl, respectively; and group II, 20.0 +/- 7.8, 20.2 +/- 7.4, and 19.8 +/- 8.8 mg/dl, respectively. Unlike HDL-cholesterol levels that remained constant with iv-fat, apolipoprotein (apo) AI concentrations increased significantly: group I, 73.0 +/- 11.0, 88.3 +/- 15.9, and 93.1 +/- 21.9 mg/dl, respectively; and group II, 31.8 +/- 10.5, 41.0 +/- 12.8, and 59.3 +/- 18.5 mg/dl, respectively. In group I infants, iv-fat is associated with an increase in larger-sized particles, particularly in the (HDL2b)gge range; in group II there is an increase in (HDL3b)gge and (HDL3c)gge components and a disappearance of particles that fall outside of the size range of normal HDL. In both groups, enteral feeding is associated with a further normalization of HDL subclass distribution. The aberrant GGE profiles and very low apoAI levels of group II infants at baseline were associated with unusual HDL morphology determined by electron microscopy where discoidal structures were prominent. With iv-fat, discoidal particles decline in number while normal spherical structures increase. Prevalence of discoidal HDL at baseline was associated with low concentrations of lecithin:cholesterol acyltransferase (LCAT) (1.12 +/- 0.5 micrograms/ml); with iv-fat this enzyme rose to 1.61 +/- 0.18 micrograms/ml. Increased LCAT is associated with the normalization of HDL morphology. It is likely that iv-fat improves the nutritional status of premature infants, thereby stimulating increased liver synthesis of important proteins, including apoAI and LCAT, associated with HDL metabolism.     

Narrative and procedural discourse in temporal lobe epilepsy.

It is well established that some individuals with temporal lobe epilepsy (TLE) demonstrate language deficits at the single word level. However, discourse production rarely has been examined quantitatively within this group. This study compared adult TLE patients with an early seizure onset (< or = age 14 years, n = 27) to a control group (n = 28) on narrative and procedural discourse tasks. As a group, the TLE patients performed normally on the procedural discourse task, but differed significantly from the controls on several narrative discourse variables. At the individual level, 30% of the TLE patients versus 4% of the controls demonstrated impaired discourse ability (p and 0.01). Within this early onset TLE group, discourse performance was not associated with demographic or seizure history variables. Considering the cognitive domain, discourse performance correlated significantly with working memory. In summary, mild discourse dysfunction was present in a significant minority of early onset TLE patients, but this deficit was not closely associated with other language measures. Discourse ability and its neuropsychological, neuroanatomical and conversational speech correlates deserve further study in TLE patients.     

Capacity related characteristics of Glyco-Gel affinity chromatographic support

We examined capacity related properties of "Glyco-Gel" (Pierce), a boronate agarose gel for separating and measuring glycated proteins by affinity chromatography. Our data indicate linear capacity to as much as 20 mg as applied hemoglobin or almost 10 mg as bound hemoglobin and 26 mg as applied serum proteins or a minimum of 2.5 mg as bound serum protein for each mL of gel. The capacity and affinity of the support for glycated proteins becomes optimum only after four regeneration cycles. The support matrix appears to have a small concentration of nonspecific binding sites equivalent to 0.09 to 0.18 mg as serum protein for each mL of gel. These sites do not bind hemoglobin. They lead to an overestimation of glycated protein that can cause large errors when the proportion of glycated protein is determined with small column loads. If near capacity loads are applied, the samples must be dialyzed or diluted to avoid decreased analytical recovery resulting from competitive and eluting properties of endogenous sugars.     

Perforin- and Fas-dependent mechanisms of natural killer cell-mediated rejection of incompatible bone marrow cell grafts

Natural killer (NK) cells eliminate target cells infected with intracellular pathogens and tumor cells by employing the granule exocytosis and death receptor pathways. They also mediate the acute rejection of incompatible bone marrow cell (BMC) grafts. However, the cytotoxic mechanisms employed during acute BMC graft rejection are obscure. Throughout these studies, BMC graft rejection was compared between two inbred strains of mice: 129 mice, which apparently use perforin- and Fas-dependent cytotoxicity, and C57BL/6 (B6) mice, which are able to exploit perforin- and/or Fas-independent mechanisms. Using perforin-knockout (PKO) mice, we have determined that the granule exocytosis pathway can play a major role in NK cell-mediated rejection of allogeneic and MHC class I-deficient BMC, depending upon the genetic background of the recipient and the environmental housing conditions. Although the granule exocytosis pathway seems to be the most potent cytolytic mechanism of NK cell-mediated rejection, alternative perforin-independent mechanisms, such as death receptor-induced apoptosis, also exist. By preventing both perforin- and Fas-mediated interactions concurrently, we observed that 129 mice were impaired in mediating MHC class I-deficient BMC rejection, while B6 mice maintained strong rejection capacities. The administration of neutralizing TNF antibodies to B6PKO mice before challenging with Fas and MHC class I double-deficient BMC still did not reverse rejection. Thus, our studies reveal the relative importance of perforin-, Fas-, and TNF-based cytotoxicity in NK cell-mediated rejection of incompatible BMC.     

Evaluation of the release of mutagens from diesel particles in the presence of physiological fluids

The Ames Salmonella typhimurium plate incorporation assay was used to evaluate the mutagenicity of organics extracted from diesel exhaust particles. Organic solvents were more efficient than physiological fluids in removing mutagens from diesel particles, with dichloromethane extracts having the greatest mutagenic activity of the solvents examined. Serum and lung cytosol were more effective than acellular lung lavage fluid in releasing mutagenic activity from diesel particles. The mutagenic activity of diesel particle organics preextracted with dichloromethane is greatly reduced upon the addition of serum and lung cytosol to organics. Subsequently, incubation of protease with serum and lung cytosol-bound diesel organics increases the mutagenic activity. Fluorescence intensity was quantitated and found to correlate with mutagenic activity in the organic and serum extracts, but not the lung cytosol extracts. These studies suggest that substantial mutagenic activity is released from diesel particles upon incubation with serum and lung cytosol.     

Distribution of glucose incorporated into macromolecular material by treponema pallidum.

Treponema pallidum was observed to incorporate glucose carbons into lipids, ribonucleic acid, deoxyribonucleic acid, and protein. Only the glycerol portions of phosphatidylcholine and phosphatidylglycerol contained glucose-derived carbons. Incorporation of exogenous choline into phosphatidylcholine was detected. Glucose was incorporated into only the pentoses of nucleic acids. About 50% of the glucose incorporated into protein was present in only one amino acid, aspartate. Evidence suggests that aspartate synthesis could follow the conversion of phosphoenolpyruvate to oxalacetic acid by a guanosine 5'-diphosphate-dependent phosphoenolpyruvate carboxykinase.     

Differential effects of external pH alteration on intracellular pH in rat coronary and cardiac myocytes

Changes in extracellular pH (pH_o) induce changes in the intracellular pH (pH_i) of cardiac myocytes that are slow and attenuated. Little however is known about the effects of changing pH_o on the pH_i of the coronary smooth muscle cells. We have therefore directly compared the effects of altering pH_o on pH_i of both coronary and cardiac myocytes. Carboxy-SNARF was used in single cells to measure pH_i. Alteration of pH_o caused corresponding changes in pH_i that were large (70–80 % of pH_o) and rapid in coronary myocytes compared to cardiac myocytes. In contrast, changes of pH_i produced by weak acids or bases produced similar pH_i responses in both types of cells. It is suggested that the differential effects of pH_o on coronary and cardiac cells may be functionally significant, as it will allow rapid alteration of coronary perfusion to meet tissue needs, while maintaining cardiac output.Supported by the BHF and MRC     

Mammalian tyrosinase-related protein-1 is recognized by autoantibodies from vitiliginous Smyth chickens. An avian model for human vitiligo.

The Smyth line (SL) chicken is an animal model for the human acquired depigmentary disorder vitiligo. Affected birds from this line express a postnatal loss of melanocytes in feather and ocular tissues. This vitiligo-like depigmentation is considered to be a disorder with two interacting components: melanocyte dysfunctions and autoimmune reactions. Previously, SL chicks were shown to express high levels of circulating autoantibodies that bind to chicken melanocyte proteins with molecular masses between 65 and 80 kd. Three mammalian melanocyte proteins known to have isoforms in this molecular mass range are tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2. Of these, only tyrosinase is reported to be expressed in chicken melanocytes. The results presented in this study indicate that, of these three candidate proteins, TRP-1 is the primary antigen recognized by the SL autoantibodies. SL autoantibodies recognize a chicken melanocyte protein that is different from that of tyrosinase or the candidate chicken TRP-2. In addition, several types of experiments incriminate TRP-1 as the primary mammalian melanocyte antigen recognized by SL autoantibodies. We further verified that chicken melanocytes expressed messages for TRP-1 by finding positive signals on Northern blots of chicken melanocyte RNA probed with mammalian TRP-1 cDNA fragments. Therefore, we conclude from these results that the SL autoantibodies primarily recognize TRP-1 in mammalian melanocytes and suggest that chicken melanocytes express a homologue of TRP-1 (the human gp75 and the murine brown/b locus protein).