Placental permeability and energy metabolism enzymes in fetuses of lipemic rats.

A model of maternal lipemia without hyperglycemia, in the rat, produced by high-fat feedings, was developed to study the effects of and abnormal maternal lipid homeostasis on placental transport of nutrients and possible alterations of key enzymes of energy metabolism in the liver and brain of the fetuses. Pregnant rats fed lower concentrations of fat served as controls. All studies were carried out in dams and fetuses one day prior to delivery. The dietary treatment of the dams and fetuses produced in the fetuses ketonemia as well as lipemia. Following a bolus of 14C-3-0-methyl-D-glucose to the dams, the levels of the tracer remained higher in the blood and brain of lipemic than in control fetuses. By contrast, there was a decrease in the fluxes of 14C-alpha-amino-isobutyric acid in the fetuses of lipemic dams as compared to controls. Among enzymes of energy metabolism, fetal liver glucose-6-phosphatase and succinic dehydrogenase were enhanced by lipemia. Fetal brain glucose-6-phosphatase was depressed. Thus, lipemia, as occurring in poorly controlled maternal diabetes, may be a factor in determining the access to the fetus of essential, neutral amino acids and alter the normal activity of energy metabolism enzymes in the fetus.

Digital flashing tomosynthesis: a promising technique for angiocardiographic screening.

A system for digital flashing tomosynthesis (DFTS) consists of four ECG-gated simultaneously flashed X-ray tubes, a 14-in image intensifier, a unit for digital subtraction angiography (DSA), a PC-hosted transputer network for three-dimensional (3-D) reconstruction as well as for quantitative coronary angiography and ventriculography, a display unit, and an individual digital archive. A presentation of DFTS tomoangiograms as a single slice or multiple slices of arbitrary thickness is available. DFTS also offers rotating and stereographic presentation of 3-D images. DFTS represents a system for standardized digital angiocardiography with digital archiving, and assures optimal reproducibility and safety. This system is feasible for both an ambulatory basis to allow high-volume cardiovascular angiographic screening by only one X-ray snapshot, and for quantification of natural progression or potential regression of coronary artery disease resulting from interventional or pharmacological therapy.

Regulation of gluconeogenesis by glycerol and its phosphorylated derivatives.

Glycerol, glycerol-3-phosphate (G3P), and dihydroxyacetone phosphate (DHAP) were evaluated as inhibitors of gluconeogenesis on rat liver enzymes in vitro, and for their effects on glucose formation in vivo in well-nourished and malnourished rats. DHAP was more potent as an inhibitor than G3P on fructose-1,6-diphosphatase (FDPase), phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (G6Pase). The I50 for DHAP was 2, 8, and 9 x 10(-3) M, respectively. No effect was observed on rat liver pyruvate carboxylase (PC). Glycerol was a weak inhibitor of FDPase and PEPCK, but did not inhibit PC and G6Pase. In vivo, when G3P was injected before a parenteral L-alanine (Ala) challenge, it produced a hypoglycemic effect in malnourished rats and a lesser, but noticeable, blood glucose level reduction in well-fed animals. Glycerol caused a smaller reduction in glucose formation from Ala. No comparable effects were observed after a fructose pretreatment. These results underscore the potential hypoglycemic effects of phosphorylated glycerol metabolites and identify the steps in gluconeogenesis where this action is exerted. The study also stresses the nutritional component in the glycerol intolerance syndrome, apparent from the far more severe effects observed in malnourished rats given G3P or glycerol prior to Ala.

Intestinal absorption of copper: effect of sodium.

The mechanisms of copper (Cu) absorption from the small intestinal lumen are poorly understood. In this study we investigated the role of sodium (Na) during the removal of Cu from the lumen of jejunal and ileal segments, using an in situ perfusion procedure in the anesthetized rat. Intestinal absorption of Cu from a 31 microM solution was highest in the presence of an isotonic concentration of NaCl, as compared to solutions containing either glycerol (GRL) or N-methyl-D-glucamine (NMG) as osmotic agents. In the jejunum, mean +/- SEM Cu absorption rates in the presence of the following solutes were: with NaCl, 57.5 +/- 10.5 pmole/min X cm; with GRL, 13.3 +/- 14.7 (P less than 0.05); with NMG, 18.4 +/- 10.1 (P less than 0.05). In the ileum, copper absorption in the presence of NaCl was 64.4 +/- 9.6; with GRL, 24.3 +/- 10.1 (P less than 0.01); with NMG, 15.8 +/- 3.7 (P less than 0.001). Kinetic analysis of the carrier-mediated component of Cu absorption in rat jejunum yielded a Vmax = 47.5 pmole/min X cm and an apparent Kt = 21 microM. The diffusion coefficient was calculated to be 1.4 X 10(-5) cm2/sec. The absorption of Cu was independent of net water absorption, which was highest in the presence of GRL and abolished and reversed into secretion by NMG. The data obtained are indicative of a significant role of Na in the small intestinal transport of Cu, in vivo, although not directly related to unidirectional water fluxes. The cation specificity of Na in this process remains to be elucidated, although the results support earlier studies which postulated that mediated transport may constitute a major component of Cu absorption in the mammalian small intestine.

Fetal glycerol metabolism in experimental maternal lipemia.

Maternal lipemia (L), one of the consequences of poorly controlled diabetes in gestation, was induced in pregnant rats by feedings of a diet containing 45% fat. The maternal condition was associated with fetal L and moderate ketonemia. L fetuses had an elevated liver glycerol kinase (EC 2.7.1.30), when assayed 1 day before term (L = 82.5 +/- 3.8 nmole/min X mg protein and controls (C) = 67.4 +/- 3.9 nmole/min X mg protein; means +/- SE, P less than 0.01). However, neither hepatic cytosolic glycerophosphate (GcPO4) dehydrogenase (EC 1.1.1.94) nor mitochondrial GcPO4 oxidase (EC 1.1.99.5) were altered. GcPO4 oxidase was lower in the striated muscle of L than in that of C fetuses (13.7 +/- 1.2 nmole/min X mg protein vs 17.2 +/- 0.5 nmole/min X mg protein, P less than 0.05). The results of the present study suggest that L, in utero, may cause an alteration in overall glycerol oxidative capacity in liver and GcPO4 in muscle. These changes appear to be compatible with a shift in the capacity of L fetuses to handle glycerol which may relate to postnatal fuel utilization by L offspring.

Regulation of hepatic gluconeogenesis and glycogenolysis by phosphorylated glycerol and glycolytic intermediates in diabetic and control Chinese hamsters.

Metabolic regulation of gluconeogenesis and glycogenolysis by two phosphorylated derivatives of glycerol, G3P, and DHAP, and by F2,6BP, was assessed in vitro in liver homogenates obtained from Chinese hamsters (C. griseus) of two types: diabetic animals from sublines with consistent glycosuria and hyperglycemia, and normoglycemic controls. Only FBPase was sensitive to inhibition by the phosphorylated metabolites. G3P was weakly inhibitory of FBPase. Addition of 7 X 10(-3) M DHAP halved FBPase activity in the diabetic hamsters and 4 X 10(-3) M DHAP produced the same effect in the controls. The other gluconeogenic enzymes and phosphorylase a were only negligibly inhibited. In contrast, F2,6BP inhibited FBPase at concentrations in the micromolar range. Liver homogenates from diabetic hamsters appeared significantly more sensitive to F2,6BP inhibition of FBPase than those from controls at concentrations 0.6 X 10(-6) M and higher. These data indicate that in well-fed hamsters phosphorylated glycerol derivatives are unlikely to regulate hepatic gluconeogenesis at physiologic concentrations. However, the effects of F2,6BP on gluconeogenesis and glycolysis may be linked to those mediated by insulin. Thus, the deficiency of insulin, elevated end-organ insulin resistance, the alteration in the glucagon-insulin interaction, or a combination of these possible causes can be involved in an abnormal regulation of glycolysis and gluconeogenesis at the FBPase step, associated with changes in F2,6BP concentration.

Zinc intestinal absorption in rats: specificity of amino acids as ligands.

The luminal phase of zinc intestinal absorption may be mediated by low-molecular-weight substances originated in digestive, metabolic or secretory processes. Amino acids are considered primary candidates for this role through the formation of complexes with zinc. However, structural characteristics that may be indispensable for this physiological function have not been explored in vivo. We investigated the comparative effectiveness of four amino acids and their respective chemically related homologues on the absorption of zinc by the jejunum, ileum and colon of the rat using a perfusion procedure. L-Tryptophan (Trp) allowed for significantly greater zinc absorption than tryptophol (Tpl) in all areas of the gut. L-Histidine (His) and imidazole (Imd) had similar effects in both the jejunum and the ileum. Imd allowed for much greater zinc absorption from the colon than did His (His, 388 +/- 31; Imd, 937 +/- 107 pmol/min X cm, P less than 0.001). Proline (Pro) was a more effective ligand than pyroglutamate (Pyr) in the ileum (Pro, 559 +/- 19; Pyr, 352 +/- 22 pmol/min X cm, P less than 0.001), but not in the jejunum or the colon. L-Cysteine was superior to N-acetyl-L-cysteine only in the ileum (508 +/- 45 vs. 348 +/- 25 pmol/min X cm, P less than 0.01). The greater zinc absorption achieved by amino acids than by non-amino acid homologues in the small intestine appeared to be due to the presence of both mediated and nonmediated transport mechanisms for amino acids but of only nonmediated zinc uptake for the homologues. In the colon, where amino acid absorption does not take place, high structural affinity for zinc, such as that exhibited by Imd, allowed for considerable absorption of the trace element.

Potential of digital flashing tomosynthesis for angiocardiographic evaluation.

A system for digital flashing tomosynthesis (DFTS) consists of four electrocardiogram-gated and simultaneously flashed x-ray tubes, a 14" image intensifier, a unit for digital subtraction angiography (DSA), a personal computer-hosted transputer network for three-dimensional (3D) reconstruction as well as for quantitative coronary angiography and ventriculography, a display unit and an individual digital archive. DFTS-tomoangiograms may be presented in single slice mode or as multiple slices of arbitrary thickness, using rotating and stereographic presentation of 3D images. DFTS represents a configuration for standardized digital angiocardiography with digital archiving and assures optimal reproducibility and safety. This angiographic configuration is feasible for both ambulatory angiography to allow high volume cardiovascular angiographic screening and for the quantitative assessment of natural progression or potential regression of coronary artery disease resulting from interventional or pharmacological therapy.

Intestinal absorption of zinc: sodium-metal-ligand interactions.

The characteristics of zinc small intestinal absorption were investigated with the purpose of clarifying the role of sodium and the possible interaction among certain amino acids, oligopeptides, and zinc with electrolyte and water absorption. A perfusion procedure was used in anesthetized rats. Physiological concentrations of zinc with no ligands, or with twice the zinc levels of either Trp, His, Pro, or a protein hydrolysate (PrH) were pumped through jejunal or ileal segments. PrH was also used at a 10: 1 ratio to zinc. The osmotic solutes were either sodium chloride, glycerol, or NMG at isotonic concentrations. In the absence of LMW ligands, zinc transport appeared to occur only by diffusion, except in the ileum and in the presence of glycerol, where at low zinc concentrations a low affinity mediated transport component could be identified (Kt = 0.67 mM; Vmax = 1,160 pmole/min.cm. Glycerol generally elicited a greater overall zinc absorption rate as well as an enhanced net water uptake than when sodium chloride was the osmotic agent when either Trp, His, or Pro was present. The data indicate that sodium is not a requirement for zinc transport. In the presence of LMW ligands, which may also be from endogenous origin, bulk flow may be a major contributor of zinc translocation across the mammalian small intestinal mucosa.

Endoscopic screening for dysplasia and mucosal aneuploidy in adolescents and young adults with childhood onset colitis.

OBJECTIVES: In adults, the premalignant nature of ulcerative colitis (UC) has long been accepted. Currently there is increasing concern that Crohn's disease (CD) may be equally premalignant. As a consequence, most adults with long-standing UC and many with chronic CD are enrolled in ongoing endoscopic cancer surveillance programs. In contrast, the risk of colonic cancer in adolescents and young adults with either form of colitis is less well recognized, and the need for dysplasia and cancer screening in this population has not been systematically evaluated. We therefore report the prospective results of colonoscopic cancer screening in such a young population. METHODS: Thirty-five adolescents and young adults with long-standing colitis (18 UC, 17 CD; 21 +/- 3 yr old, 11 +/- 3 yr colitis duration) underwent colonoscopic cancer screening. All had multiple biopsies for flow cytometry and light microscopy. RESULTS: Seven subjects had aneuploidy (3/18 UC, 4/17 CD). Of these seven, only two had dysplasia [one high grade (UC), one low grade (CD)]. One additional subject had indefinite dysplasia with normal flow cytometry. The remaining 27 subjects had both normal flow cytometry and light microscopy. Five of the seven aneuploid subjects underwent surgery within 1 yr of screening. Four, including both subjects with dysplasia, had no evidence of colon cancer at surgery. However, a 24-yr-old female with a 14-yr history of UC and no evidence of dysplasia or cancer at screening had a Dukes C adenocarcinoma. CONCLUSIONS: Adolescents and young adults with childhood onset UC or CD are at risk for aneuploidy, dysplasia, and colon cancer. Aneuploidy can be evident 10 yr after the onset of colitis and in patients as young as 16 yr of age. Therefore, the risk for colon cancer in patients with childhood onset colitis must be based on the duration of the illness, not on their chronological age. Incorporation of flow cytometry into an endoscopic screening protocol appears to enhance the ability to identify individuals at highest risk for colon cancer.

The concept of archiving unedited and edited digital coronary angiograms.

Digital image data acquired during cardiac catheterization will soon be archived on standardized digital storage media. However, with the enormous amount of generated data, considerable time will be wasted at later reviewing or at conferences, or when performing additional quantitative studies. As a result major advantages of a digital acquisition and archiving technique will be lost. The concept of two way archiving includes an unedited (primary) digital archive as well as a (secondary) archive edited by operator guided "intelligent" data reduction (IDR). IDR is based upon the elimination of useless and redundant frame sequences (FS), documentation of coronary interventions on one representative single frame (F) and on the reduction of relevant FS and physiological data to and ECG-controlled representative cardiac cycle (CC). With a heart rate of 72/min and an acquisition rate of 12.5 F/s a documentation of each FS may be obtained with only 10 F. A redundancy-free set of 130 F of a diagnostic study as well as only 41-85 F of an interventional study will be archived on an individual 3.5" MOD or on a CD-R. Two cardiologists and two cardiosurgeons studied independently 24 IDR-edited and the corresponding unedited digital angiograms and found no significant differences in the diagnostically relevant coronary morphology and left ventricular function. IDR provides an edited digital coronary angiogram, e.g. a set of images free of redundance and without loss of relevant information. Uneditable FS can be archived in their unedited (primary) form. IDR is managed on-line by an operator interacting with the angiographer.

Impact of compensatory enlargement of atherosclerotic coronary arteries on angiographic assessment of coronary artery disease.

To determine whether compensatory enlargement of atherosclerotic coronary arteries occurs and to what degree it affects the angiographic assessment of coronary artery disease, we performed postmortem coronary angiography of 30 human hearts with suspected coronary artery disease and studied 70 histologic cross sections of the proximal left anterior descending artery and proximal right coronary artery. Angiographic and morphometric analyses of 50 stenoses in proximal and middle sections of the left anterior descending artery, right coronary artery, and left circumflex artery were performed. The control group of 10 human hearts without suspected coronary artery disease was evaluated in the same way. For this purpose, coronary arteries were filled with a methylmethacrylic radiopaque resin at a pressure of 100 mm Hg and closely embedded in a methylmethacrylic resin by use of which shrinkage and mechanical artifacts could be avoided. The area circumscribed by the internal elastic lamina was taken as a measure of the area of the arterial lumen if no plaque had been present. The angiographic and corresponding morphometric degree of stenosis was assessed. A significant correlation (r = 0.85, p less than or equal to 0.0001) was found between the internal elastic lamina area and the area of the plaque (lesion area), suggesting that coronary arteries may enlarge as lesion area increases. With the morphometric degree of stenosis, the expected anatomic diminution of the coronary artery was abolished (r = 0.79, p less than or equal to 0.0001), indicating compensatory enlargement in atherosclerotic segments. Accordingly, the degree of stenosis assessed from in vitro angiograms was underestimated. Compensatory coronary enlargement of the stenotic segment was the main reason for angiographic underestimation. The underestimation factor of up to 3.50 for very mild stenoses decreased to 1.37 at an angiographic degree of 50% area stenosis and 30% diameter stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Synergism of cytotoxic effects of vinorelbine and paclitaxel in vitro.

Empiric combinations of vinca alkaloids with taxanes have been recently used in clinical oncology. To enhance the activity of these two classes of agents, we evaluated the sequence and duration of exposure, looking for synergistic effects. Cell lines DU 145, PC 3, LnCaP, LL 86, MCF7wt, and MCF7/ADR (NCI/ADR-RES) were incubated with varying concentrations of paclitaxel or vinorelbine. Cytotoxicity was evaluated by a semiautomated MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) method. Synergism or antagonism of these two agents either sequentially or in combination was determined by median effect analysis. Prolonged exposure of cells to either drug enhanced cytotoxic effect. Synergism or antagonism with vinorelbine and paclitaxel were both sequence dependent and cell line specific. In the case of MCF7wt, synergism was seen when a 48-hr exposure to vinorelbine preceded paclitaxel, whereas antagonism was noted when both agents were applied simultaneously or when the sequence was reversed. Concurrent vinorelbine and paclitaxel were synergistic in four of six cell lines when the exposure was extended to 96 hr but not for shorter durations of exposure. Sequential exposure of vinorelbine preceding paclitaxel or prolonged exposure to both agents concurrently needs to be tested clinically to determine whether the antitumor activity of this combination can be enhanced. In addition, these studies suggest concurrent administration of these two agents may lead to a less than optimal cytotoxic result.

Prospective analysis of colorectal carcinoma. Determination of an age-site and stage relationship and the correlation of DNA index with clinicopathologic parameters.

PURPOSE: A prospective study of colorectal cancer (1987-1991) using flow cytometry was performed to determine the relationship of age with DNA index (DNA-I), sites of disease, Dukes stage, grade, and survival. METHODS: The flow cytometry was performed on 138 fresh, unfixed, surgical specimens using 4',6'-diamidino-2-phenylindole, a DNA fluorochrome. RESULTS: The mean age was 66.9 (42.8 percent > or = 70; range, 22-92; median, 68) years, and 48.6 percent were female. The patients' stages were (in percent): A, 4.4; B, 53.0; C, 38.2; D, 4.4. Tumor grades of differentiation (in percent) were well, 14.4; moderate, 68.9; poor, 16.7; and sites (in percent) were: rectum, 19.6; sigmoid/left, 50.7; transverse/right, 29.0. Aneuploidy (DNA-I not equal to 1.0; CV, 3.5 percent) was found in 58.8 percent. Age (by decade of presentation) was compared with site and Dukes stage. Older patients had more transverse/right-sided lesions (P = 0.003). Patients with Dukes C and D tumors had a lower age (by decade of presentation) than patients with B2 lesions (P = 0.03). Age was not related to DNA-I or grade or DNA-I with sex, grade, site, stage, or survival (P > 0.05). CONCLUSIONS: This prospective study suggests that colorectal cancer tends to present at an earlier stage and in the more proximal colon in the older population. Because right-sided lesions are beyond the reach of sigmoidoscopy, these findings have prognostic and screening implications.

Digital flashing tomosynthesis (DFTS)--a technique for three-dimensional coronary angiography.

Digital Flashing Tomosynthesis (DFTS) represents a technique for three-dimensional (3D) coronary angiography. Four ECG-gated simultaneously flashed X-ray tubes generate a multiperspective digital substraction image as DFTS multiangiogram for 3D reconstruction and visualization. Computerized morphologic and morphometric quantitative analysis can be performed including videodensitometry. Postmortem coronary angiography of 30 human hearts with suspected coronary artery disease was performed by 35-mm cine technique and by DFTS. The results of angiographic measurements in 50 stenotic arterial segments were compared with the histologic reference and show excellent regression results with correlation coefficients of more than 0.95 (p less than or equal to 0.0001). No significant differences in standard errors of estimates between the techniques were found. DFTS yields an accuracy in depiction of the coronary arteries and angiographic estimation of arterial lumen equivalent to 35-mm cineangiography. DFTS images can be directly used for visual interpretation and for computerized morphologic and morphometric quantitative analysis. DFTS technology reduces the amount of radiation exposure, the amount of contrast medium, and the time of the procedure. DFTS offers the possibility to obtain 3D images of the coronary artery tree.