Three-dimensional reconstruction of color Doppler flow convergence regions and regurgitant jets: an in vitro quantitative study

OBJECTIVES

This study sought to investigate the applicability of a current implementation of a three-dimensional echocardiographic reconstruction method for color Doppler flow convergence and regurgitant jet imaging.

BACKGROUND

Evaluation of regurgitant flow events, such as flow convergences or regurgitant jets, using two-dimensional imaging ultrasound color flow Doppler systems may not be robust enough to characterize these spatially complex events.

METHODS

We studied two in vitro models using steady flow to optimize results. In the first constant-flow model, two different orifices were each mounted to produce flow convergences and free jets--a circular orifice and a rectangular orifice with orifice area of 0.24 cm(2). In another flow model, steady flows through a circular orifice were directed toward a curved surrounding wall to produce wall adherent jets. Video composite data of color Doppler flow images from both free jet and wall jet models were reconstructed and analyzed after computer-controlled 180 degrees rotational acquisition using a TomTec computer.

RESULTS

For the free jet model there was an excellent relation between actual flow rates and three-dimensional regurgitant jet volumes for both circular and rectangular orifices (r = 0.99 and r = 0.98, respectively). However, the rectangular orifice produced larger jet volumes than the circular orifice, even at the same flow rates (p < 0.0001). Calculated flow rates by the hemispheric model using one axial measurement of the flow convergence isovelocity surface from two-dimensional color flow images underestimated actual flow rate by 35% for the circular orifice and by 44% for the rectangular orifice, whereas a hemielliptic method implemented using three axial measurements of the flow convergence zone derived using three-dimensional reconstruction correlated well with and underestimated actual flow rate to a lesser degree (22% for the circular orifice, 32% for the rectangular orifice). In the wall jet model, the jets were flattened against and spread along the wall and had reduced regurgitant jet volumes compared with free jets (p < 0.01).

CONCLUSIONS

Three-dimensional reconstruction of flow imaged by color Doppler may add quantitative spatial information to aid computation methods that have been used for evaluating valvular regurgitation, especially where they related to complex geometric flow events.

Effect of acute exhausting exercise on cytokine gene expression in men

Because of recent interest in the effects of physical exercise on immunologic function, we decided to use state-of-the-art methods to evaluate cytokines in the peripheral blood leukocytes (PBLs) of 7 men before and after a maximal treadmill stress test. Change in cytokine gene expression was quantified from PBLs using a reverse transcriptase polymerase chain reaction assay (RT-PCR). In contrast to reports on serum levels or using in vitro testing, direct gene expression of TNF-alpha decreased after the stress test (p < 0.008). However, the 47% decrease was relatively small and of questionable biological significance. Levels of IL-1a, IL-1b, IL-2, IL-4, IL-6, IL-10, and INF-gamma did not change.

Multiple structural elements define the specificity of recombinant human inhibitor-1 as a protein phosphatase-1 inhibitor

The cDNA encoding human brain protein phosphatase inhibitor-1 (I-1) was expressed in Escherichia coli. Following PKA phosphorylation at a threonine, recombinant human I-1 was indistinguishable from rabbit skeletal muscle I-1 as a potent and specific inhibitor of the type-1 protein serine/threonine phosphatase (PP1). N-Terminal phosphopeptides of I-1 that retained the selectivity of intact human I-1 highlighted a functional domain that mediates PP1 inhibition. Substituting alanine in place of threonine-36 eliminated I-1 phosphorylation by PKA and its phosphatase inhibitor activity. An acidic residue was substituted in place of the phosphoacceptor to produce I-1(T35D), a constitutive phosphate inhibitor. I-1(T35D) was an equally effective inhibitor of PP1 and the type-2 phosphatase, PP2A. However, CNbr digestion of I-1(T35D) yielded an N-terminal peptide that showed 100-fold increased specificity as a PP1 inhibitor. This provided new insight into a unique conformation of the phosphorylated I-1 that accounts for selective inhibition of PP1 activity. Truncation of an active I-1 phosphopeptide identified an N-terminal sequence that was reduced in addition to threonine-35 phosphorylation to inhibit PP1 activity. Biosensor studies demonstrated that PP1 bound to both Phosphorylated and dephosphorylated I-1 and suggested that distinct elements of I-1 structure accounted for PP1 binding and inhibition. Our data point to multiple interactions between the I-1 functional domain. and the PP1 catalytic subunit that define this phosphoprotein as a physiological regulator of the type-1 protein phosphatase.

[The study of DNA fingerprint of hydatidiform moles and the clinical outcome]

OBJECTIVE

To study the genetic origin of hydatidiform moles (HM) and the clinical outcome.

METHODS

41 cases of hydatidiform mole were collected mainly from Beijing area and studied for genetic components by DNA fingerprints. The diagnosis of persistent gestational trophoblastic disease (PTD) was made if blood hCG remained higher than normal 8 weeks after mole evacuation.

RESULTS

Among 41 HM samples, 32 produced identifiable DNA fingerprints. DNA from only paternal origin was found in 21, in which 6 were PTD, DNA from both parents in 11, none of which developed PTD.

CONCLUSIONS

DNA from only paternal origin was more frequently found than from both parents in HM, and there was a higher risk of PTD in the former group than in the latter.

Basic fibroblast growth factor (FGF-2) affects development of acoustico-vestibular neurons in the chick embryo brain in vitro

The effects of basic fibroblast growth factor (FGF-2) on presumptive auditory and vestibular neurons from the medulla were studied in primary cell cultures. The part of the rhombic lip that forms nucleus magnocellularis (homologue of the mammalian anteroventral cochlear nucleus) was explanted from white leghorn chicken embryos at Hamburger-Hamilton stage 28 (E5.5), the time when precursors of the magnocellularis bushy cells migrate and begin to differentiate in situ. In vitro the neuroblasts migrated onto 2-D substrates of purified collagen, differentiated, and expressed neuronal markers. One-half of the cultures were supplemented with human recombinant FGF-2 (10 ng/ml daily) for 5-7 days; the others, with fetal bovine serum. FGF-2 more than doubled the length of neurite outgrowth during the first 3 day treatment compared to serum, but the number of migrating neuroblasts was unaffected. Although neurites attained greater lengths in FGF-2, they usually degenerated after 4-5 days; in serum their growth continued for several weeks. Differentiation of neuronal structure, including axons and dendrites, began within 1-2 days in bFGF but required at least 5-7 days in serum. Histochemical observations in vitro and in situ with antibodies to FGF receptor demonstrated immunopositive patches on acoustico-vestibular neuroblasts at stage 28, when they are migrating and first forming their axons. The findings suggest that FGF-2 stimulates neurite outgrowth in the cochlear and vestibular nuclei. FGF-2 may accelerate cell death by overstimulating neuroblasts, but other factors are needed to sustain their further development.

A modified operation for Hirschsprung's disease: Posterior longitudinal anorectal split with a "heart-shaped" anastomosis

A variety of complications can arise after the definitive pull-through operation for Hirschsprung's disease. Among these are constipation and soiling, which may be due to mismanagement of the internal anal sphincter. In order to prevent these complications, we developed an improved operative procedure based on preservation of the anterior anorectum that utilizes a posterior longitudinal split with an oblique anastomosis. Forty patients underwent this procedure over a 4-year period; adequate follow-up was obtained in 34 cases. Mean age at operation was 13 months (range 3 months to 7 years). A primary pull-through without a colostomy was performed in 38 of the 40 patients. The results showed excellent preservation of function, with a mean follow-up of 5 years and 7 months. There was no occurrence of spastic stenosis of the internal sphincter, no incontinence, and minimal constipation or soiling.

[Induced-expression of MHC-DR molecules on mice islet cells]

The correlation of induced-expression of MHC-DR molecules with insulin release in cultured mice islet cells has been studied. The results showed that, (1) No detectable induced-expression of MHC-DR molecules by TNF-alpha alone at the concentration of 50-100 U/ml has been assayed, but the induced-expression of MHC-DR molecules has been identified in a few islet cells (8.5 +/- 2.9%) with IFN-r alone at concentration of 50-100 U/ml. (2) The induced-expression of MHC-DR molecules has been detected in as high as 80% of cultured islet cells with TNF-alpha and IFN-r combined at different concentrations. (3) Insulin released from cultured islet cells was enhanced by IFN-r and TNF-alpha either alone or combined at different concentrations. These results suggest that the induced-expression of MHC-DR molecules themselves does not damage the function for insulin release in cultured islet cells.

Synthesis and evaluation of the antiproliferative effects of 1-O-hexadecyl-2-O-methyl-3-O-(2'-acetamido-2'-deoxy-beta-D- glucopyranosyl)-sn-glycerol and 1-O-hexadecyl-2-O-methyl-3-0- (2'-amino-2'-deoxy-beta-D-glucopyranosyl)-sn-glycerol on epithelial cancer cell growth

Two ether glucosyl diglyceride analogs were synthesized, and their antiproliferative activity against four epithelial cancer cell lines was evaluated. 1-O-Hexadecyl-2-O-methyl-3-O-(2'-acetamido-2'-deoxy-beta-D- glucopyranosyl)-sn-glycerol (4) was synthesized by reaction of 2-acetamido-2-deoxy-3,4,6-tri-O-acetyl-alpha-D-glucopyranosyl chloride with 1-O-hexadecyl-2-O-methyl-sn-glycerol followed by deacetylation by methanolic hydrolysis. The N-acetyl group of 4 was removed by hydrolysis with ethanolic potassium hydroxide to form 1-O-hexadecyl-2-O-methyl-3-O-(2'-amino-2'-deoxy-beta-D-glucopyranosyl)- sn-glycerol (5). Compounds 4 and 5 inhibited the proliferation of MCF-7, A549, A427, and T84 cancer cell lines. The IC(50) values for 5 ranged from 6.5 to 12.2 microM, whereas 4 was more effective against A549 cells (IC(50) 9 microM) than against MCF-7 (IC(50) 17 microM) and A427 (IC(50) 25 microM) cells and was inactive against T84 cells. Under identical incubation conditions, compounds 4 and 5 were potent inhibitors of the proliferation of OVCAR-3 cells with IC(50) values of 12 and 4 microM, respectively, whereas ET-18-OCH(3), hexadecylphosphocholine, and erucylphosphocholine had IC(50) values of 24, >30, and >30 microM, respectively. The cell-inhibitory profile of these ether-linked glucosyl diglycerides strengthens the hypothesis that such glycolipids represent a distinct group of antitumor ether lipids, having antineoplastic activities that differ from the well-known alkylphosphocholines and alkyllysophospholipids.

Direct evidence that initial oxidative stress triggered by preconditioning contributes to second window of protection by endogenous antioxidant enzyme in myocytes

BACKGROUND

We tested the hypothesis that late preconditioning is associated with increased antioxidant enzyme activity induced by initial oxidative stress.

METHODS AND RESULTS

Isolated rat myocytes were preconditioned either with two cycles of 5 minutes of anoxia and 5 minutes of reoxygenation or with exogenous superoxide anion (O2-) generated by reaction of xanthine oxidase with xanthine. Myocytes were allowed to recover for 60 minutes or 24 hours, after which they were subjected to 60 minutes of anoxia and 60 minutes of reoxygenation. After 60 minutes or 24 hours, the protection was evidenced by decreased O2- production, increased Mn superoxide dismutase (Mn-SOD) activity, increased call viability, decreased LDH release, reduced malondialdehyde formation, high-energy phosphate preservation, and improved call morphology in preconditioned and O2(-)-treated myocytes. Immediately after treatment with O2- or repetitive, brief anoxia, O2- production was increased in myocytes. Longer anoxia resulted in loss of Mn-SOD activity in anoxic controls 24 hours later, whereas it was significantly increased in preconditioned and O2- -treated myocytes. O2- production was inhibited in preconditioned and O2(-)-myocytes. Myocytes treated with Mn-SOD during short, intermittent anoxia exhibited decreased activity of Mn-SOD and increased O2- production 24 hours later. Mn-SOD activity in late preconditioning was considerably higher than that in classic preconditioning.

CONCLUSIONS

These results suggest that a burst of oxygen free radicals generated during the initial periods of brief, repetitive anoxia increases myocardial antioxidant activity 24 hours later and that it contributes to the late cardioprotective effect of preconditioning.

Basic fibroblast growth factor affects neuronal migration and differentiation in normotypic cell cultures from the cochleovestibular ganglion of the chick embryo

To study the role of basic fibroblast growth factor (FGF-2) in the development of sensory neurons, the cochleovestibular ganglion of the chicken embryo provides a well-characterized structure. This permits use of morphological markers in a cell culture preparation comparable to the normal embryo (normocytic). Otocysts were explanted from white leghorn embryos at Hamburger-Hamilton Stages 14-16, when ganglion cell precursors normally start migrating from the otic epithelium. The cultures were supplemented with either fetal bovine serum or human recombinant FGF-2 (in defined medium or serum) for 2 or 5 days. FGF-2 increased explant growth, neuroblast migration, and neurite outgrowth 2- to 10-fold in the first 2 days. Neuronal morphology appeared within 2-3 days with FGF-2 but required at least 4-5 days with serum. FGF-2 in defined medium stimulated early migration and differentiation, but without serum led to degeneration after 5 days. In serum, growth was later and slower but continued for at least 3 weeks. When explants were cultured in serum with a neutralizing antibody to FGF-2, but no FGF added, neuroblast migration and elongation were decreased by 2- to 4-fold, compared to serum alone. Immunocytochemistry demonstrated FGF receptor sites on the migrating ganglionic neuroblasts, on their processes and growth cones, and in the incipient ganglion and otic epithelium at Stages 15-17, both in the embryo and in vitro. The findings suggest that FGF-2 stimulates early migration and differentiation of ganglion cells by activating the receptors of neuroblasts or their precursors in the embryonic otocyst. However, other factors must sustain their later development.

Disruption of the Cr2 locus results in a reduction in B-1a cells and in an impaired B cell response to T-dependent antigen

Covalent attachment of activated products of the third component of complement to antigen enhances its immunogenicity, but the mechanism is not clear. This effect is mediated by specific receptors, mCR1 (CD35) and mCR2 (CD21), expressed primarily on B cells and follicular dendritic cells in mice. To dissect the role of mCR1 and mCR2 in the humoral response, we have disrupted the Cr2 locus to generate mice deficient in both receptors. The deficient mice (Cr2-/-) were found to have a reduction in the CD5+ population of peritoneal B-1 cells, although their serum IgM levels were within the range of normal mice. Moreover, Cr2-/- mice had a severe defect in their humoral response to T-dependent antigens that was characterized by a reduction in serum antibody titers and in the number and size of germinal centers within splenic follicles. Reconstitution of the deficient mice with bone marrow from MHC-matched Cr2+/+ donors corrected the defect, demonstrating that the defect was due to B cells themselves. These results indicate an obligatory role of B cell complement receptors in responses of the B cells to protein antigens.

Effect of vitamin A deficiency on the early response to experimental Pseudomonas keratitis

PURPOSE

Vitamin A-deficient humans and animals are more susceptible to infections than are healthy humans and animals. This study compares the early corneal response (within 24 hours) to an experimental Pseudomonas aeruginosa infection between vitamin A deficient and control rats.

METHODS

Male WAG/Rij/MCW rats were fed either a vitamin A- deficient diet (A-) or the same diet with retinyl palmitate added back in a nonrestricted manner (N) or under pair-fed conditions (A+) to yield weight-matched rats. Some A-rats were repleted wih retinyl palmitate 16 days before being killed and then given free access to the retinyl palmitate-supplemented diet (R). Twenty-four hours before being killed, the corneas of anesthetized rats were scratched and P. aeruginosa organisms were applied to the corneal surface. The rats were killed using an overdose of sodium pentobarbital. Corneas were either processed for light and electron microscopic examination or extracted for proteinase and myeloperoxidase determination. Corneal myeloperoxidase concentrations relative to neutrophil myeloperoxidase concentrations were used to determine the number of neutrophils in the cornea. Zymography was used to study caseinases, gelatinases, and plasminogen activators. Reverse zymography was used to detect proteinase inhibitors. Similar results were noted at early, mid, and late weight plateau stages of vitamin A deficiency.

RESULTS

Ulceration occurred within 24 hours when low numbers of P. aeruginosa (10(4) cpu) were applied topically onto scratched A- corneas, whereas no ulceration was observed in the A+, R, and N corneas. When higher numbers of P. aeruginosa (10(7)-10(8)) were applied to the scratched corneas, all corneas became ulcerated within 24 hours. The extent of ulceration in the control corneas was greater than that in A- corneas by a factor of two. Only the A- corneas contained inflammatory cells with unusual striated deposits in phagolysosomes. The total number of neutrophils in the cornea and the concentrations of caseinases, plasminogen activators, and gelatinases in the infected corneal extracts were similar; however, the concentrations of cysteine proteinase inhibitors were elevated under A- conditions.

CONCLUSIONS

Vitamin A deficiency alters the response of the cornea to a P. aeruginosa infection during the first 24 hours. The alterations observed are probably due to multiple factors: an insufficient tear film for bacterial clearance and migration of neutrophils, epithelial keratinization, alterations in corneal wound healing, and changes in polymorphonuclear function.

The weight gain and ultimate adiposity in cafeteria diet - induced obesity is unrelated to the central serotoninergic tonus

Early detection of subjects with a propensity to obesity might be of great help for setting up preventive intervention studies. In this study we tested whether the development of obesity in Wistar rats, given ad libitum cafeteria foods, could be predicted by a low prolactin (PRL) response to 5-hydroxytryptophan (5HTP), as an index of low hypothalamic serotoninergic tonus. Basal and 5HTP-stimulated (50 mg/kg body weight i.p.) PRL were measured by RIA in 15 young male Wistar rats, whose pelleted diet was afterwards supplemented with cafeteria foods. In the tested animals an increase of PRL between 4 and 56 times the basal value was observed 60 min after the 5HTP injection. After 2 months of feeding, marked inter-individual differences in weight gain between the cafeteria fed animals were observed. After 10 months of feeding, median body fat percentage, assessed by dual X-ray absorptiometry, of the overfed rats was significantly higher than that of control animals: median (range): 41.2% (28.9-51.5%) vs 25.1 (18.0-32.2%) (p <0.0001). The PRL response at the start of the experiment was neither correlated with the monthly weight increases, nor with the fat mass percentage at the end of the experiment, suggesting that a pre-existing low hypothalamic serotoninergic tonus is probably not involved in the overeating and ultimate overweight of cafeteria diet fed animals.

[A study of the association between EBV and B-cell lymphoma]

Extensive studies have demonstrated that Epstein-Barr virus (EBV) is associated with Burkitt's lymphoma, immunodeficiency related lymphoma, Hodgkin's disease and T-cell lymphoma. In order to investigate whether an association exists between EBV and B-cell lymphoma in patients without overt immunodeficiency, we examined 127 B-cell lymphomas without overt immunodeficiency for expression of EBV-encoded small RNA (EBER-1) using RNA/RNA in situ hybridization. EBER-1 expression was found in nuclei of tumor cells in 8 of 127 cases (6.3%) of B-cell lymphomas. This result is similar to that of studies in Europe and the United States (about 5%). The low frequency of EBV in B-cell lymphomas suggests that EBV does not pay an important role in the pathogenesis of B-cell lymphomas without overt immunodeficiency.

Preconditioning of bovine endothelial cells. The protective effect is mediated by an adenosine A2 receptor through a protein kinase C signaling pathway

We tested the hypothesis that anoxic preconditioning could protect coronary endothelial cells against anoxic and reoxygenation injury and that this preconditioning effect could be mediated by an adenosine A2 receptor via the protein kinase C (PKC) pathway. Cells were preconditioned with 10-minute anoxia and 10-minute reoxygenation and were then subjected to anoxia for 60 minutes, followed by 120 minutes of reoxygenation. In some groups, the preconditioning effect was prevented by 8-sulfophenyltheophylline (SPT [50 mumol/L], a nonselective adenosine receptor antagonist), or calphostin C (100 nmol/L, a PKC inhibitor). In other groups, 2-p-(2-carboxyethyl)phenethylamino-5'N-ethylcarboxyamido- adenosine (CGS-21680 [20 nmol/L], an adenosine A2 receptor agonist, R-(--)-N6-(2-phenylisopropyl)-adenosine (R-PIA [50 nmol/L], an adenosine A1 receptor agonist), or 4 beta-phorbol 12-myristate 13-acetate (PMA [100 nmol/L], a PKC activator) was given as a pretreatment to mimic the preconditioning effect. Endothelial cells were also pretreated with 100 nmol/L calphostin C to confirm whether inhibition of PKC can block the effects of adenosine A2 receptor activation by CGS-21680 on anoxia and reoxygenation injury. Preconditioning reduced LDH release, increased adenosine release, promoted translocation of PKC from cytosol to membrane, increased cell viability, and preserved ATP content and cell morphology. Pretreatment with either CGS-21680 or PMA resulted in protection similar to that seen with anoxic preconditioning. The protection was totally abolished by SPT or calphostin C. The results suggest that (1) preconditioning protects coronary endothelial cells against anoxia and reoxygenation injury, (2) the protection is probably mediated by activation of adenosine A2 receptors through the PKC pathway, and (3) the preservation of endothelial cells may be one of the mechanisms of myocardial preconditioning.

The ability of bile to scavenge superoxide radicals and pigment gallstone formation in guinea pigs

After partial ligation of the common bile duct (CBD) of guinea pigs, 14 of 16 animals developed pigment gallstones within one week (S group). Intraperitoneal injection of Vit. E and C, each 10 mg/kg daily from 3 days before CBD ligation to one week after the operation (S+V group), decreased the gallstone incidence to 5/14 (exact probability < 0.01). The gallstone incidence in the control group, that only received laparotomy without ligation of the CBD, was 0/15. Biochemical analysis of the gallbladder bile showed that stricture of the CBD was associated with a significant increase in levels of unconjugated bilirubin (UCB) and Ca2+ (p < 0.05 and < 0.01). Simultaneously the scavenging rate (SR) of superoxide radical in bile significantly decreased (p < 0.05). Comparing S+V group with S group, the effect of Vit. E and C on the concentrations of UCB and Ca2+ in bile was not significant (both p > 0.05), but Vit. E and C normalized the SR, and the difference between S group and S+V group was significant (p < 0.05). These results suggested that Vit. E and C, known as antioxidants, enhanced the ability to scavenge oxygen radical in S+V group; and that in addition to the increases of UCB and Ca2+ concentrations, the participation of oxygen radicals might be of importance for pigment gallstone formation induced by bile duct obstruction.

Biological degradation and composition of inedible sweetpotato biomass

Many challenges are presented by biological degradation in a bioregenerative Controlled Ecological Life Support System (CELSS) as envisioned by the U.S. National Aeronautics and Space Administration (NASA). In the studies conducted with biodegradative microorganism indigenous to sweetpotato fields, it was determined that a particle size of 75 microns and incubation temperature of 30 degrees C were optimal for degradation. The composition of the inedible biomass and characterization of plant nutrient solution indicated the presence of potential energy sources to drive microbial transformations of plant waste. Selected indigenous soil isolates with ligno-cellulolytic or sulfate-reducing ability were utilized in biological studies and demonstrated diversity in ability to reduce sulfate in solution and to utilize alternative carbon sources: a lignin analog--4-hydroxy, 3-methoxy cinnamic acid, cellulose, arabinose, glucose, sucrose, mannitol, galactose, ascorbic acid.

Detection of bromobenzene-induced hepatocellular necrosis using magnetic resonance microscopy

The authors used magnetic resonance (MR) microscopy to assess hepatic tissue damage induced by bromobenzene both in living rats and in fixed rat liver tissues. Experiments were conducted at 7 Tesla on three groups of Fisher rats treated with bromobenzene at a single dose of 68, 135, and 269 mg/kg, respectively. Optical microscopy of hematoxylin and eosin stained sections showed liver damage only at the highest dose, whereas with MR microscopy, tissue alterations were detected at all three doses both in vivo and ex vivo. The contrast mechanism of the superior sensitivity of MR microscopy is believed to be related to the changes in local diffusion coefficients that accompany cellular degeneration and death, although other contrast mechanisms may also be involved. The superior sensitivity of MR microscopy, as demonstrated in this study, has many implications for potential use of MR techniques to perform in vivo histology.

Distribution of growth-associated class I alpha-tubulin and class II beta-tubulin mRNAs in adult rat brain

A comprehensive survey of class I alpha-tubulin (alpha 1) and class II beta-tubulin (beta II) mRNAs was performed using in situ hybridization in order to determine the extent of continued expression of these immature tubulin isotype mRNAs in the adult rat brain. Qualitatively similar distributions of the two isotype mRNAs were observed, with marked variations in hybridization intensity of both probes apparent across different brain regions. Neurons in a wide variety of structures throughout the brain exhibited intense hybridization signals. While the presence of large numbers of neurons with a moderate hybridization intensity could account for the relatively high level of total binding in some regions such as the cerebellar and dentate granule layers, in most cases higher regional mRNA levels reflected greater hybridization intensity per neuron. Little variability in hybridization intensity was typically seen between individual cells within specific nuclei throughout the brain. The presence of occasional intensely labeled neurons scattered throughout the basal ganglia provided the most striking exception to this pattern. While no qualitative differences between the distributions of alpha 1-tubulin and beta II-tubulin mRNAs were observed, consistent differences in the relative intensity of hybridization for alpha 1-tubulin versus beta II-tubulin mRNA were apparent in a few brain regions. Expression by glia did not appear to contribute significantly to detectable levels of either alpha 1-tubulin or beta II-tubulin mRNA. These findings suggest that continued expression of growth-associated tubulin isotype mRNAs may have functional significance in specific neuronal populations of the adult brain. Partial overlap between the distributions of alpha 1- and beta II-tubulin mRNAs and that of GAP-43 mRNA is discussed, as are potential roles for growth-associated tubulin gene expression in supporting cytoskeletal turnover, reactive axonal growth, and dendritic remodeling in the adult brain.

Interaction of singlet oxygen with 5'-nucleotidase in rat hearts

This study was aimed to determine whether singlet oxygen (1O2) attenuates 5'-nucleotidase activity in the ischemic myocardium. Isolated rat hearts were exposed to either exogenous 1O2 produced by irradiating rose bengal or 40-min ischemia and reperfusion. Ecto-5'-nucleotidase activity was inhibited by exogenous 1O2 (3.74 +/- 0.38 mumol/min/g dry weight), when compared with normal control (7.52 +/- 0.41 mumol/min/g dry weight; P < 0.05). The enzymatic activity was significantly preserved by histidine (25 mM)--a 1O2 scavenger (7.04 +/- 0.61 mumol/min/g dry weight; P < 0.05 v rose bengal group). After ischemia, the activity of ecto-5'-nucleotidase was greatly reduced (2.51 +/- 0.25 mumol/min/g dry weight), when compared with normal control. Histidine significantly enhanced ecto-5'-nucleotidase activity (6.55 +/- 0.52 mumol/min/g dry weight, P < 0.05 v ischemic control). Adenosine release was consistent with ecto-5'-nucleotidase activity. The time course studies of effects of 1O2 on coronary flow, cardiac function, and LDH release revealed that the damage by 1O2 to ecto-5'-nucleotidase activity and adenosine release primarily accounted for impaired coronary flow, cardiac dysfunction, and impaired cardiac metabolism. Lipid peroxidation induced by exogenous 1O2 or ischemia was in parallel with ecto-5'-nucleotidase deactivation by 1O2. It is concluded that 1O2 causes inactivation of ecto-5'-nucleotidase and attenuation of adenosine release which could possibly be one of the important mechanisms of oxygen radical-mediated myocardial injury.

Coordinated upregulation of alpha 1- and beta II-tubulin mRNAs during collateral axonal sprouting of central peptidergic neurons

An in situ hybridization study was performed to determine the relationship between levels of mRNAs for the axonal growth-associated alpha 1-tubulin and beta II-tubulin isotypes and the process of collateral axonal sprouting by identified central nervous system (CNS) neurons. A unilateral hypothalamic knife-cut was used to hemisect the hypothalamoneurohypophysial tract, which results in a robust collateral sprouting response by the uninjured neurons of the contralateral supraoptic nucleus (SON) (Watt and Paden: Exp Neurol 111:9-24, 1991). At 10 and 30-35 days after the lesion, cryosections of the SON were obtained and hybridized with 35S-labeled cDNA probes specific to alpha 1- and beta II-tubulin mRNAs. Quantitative evaluation of the resulting autoradiographs revealed that alpha 1-tubulin mRNA levels were significantly increased by 10 days in SON neurons that were undergoing collateral sprouting compared to controls and that this increase was sustained at 30-35 days post-lesion. Less marked increases in hybridization intensity of the beta II-tubulin probe were also apparent in sprouting neurons at both 10 and 30-35 days after the lesion, but were statistically significant only at 10 days. The measured increases in intensity of hybridization of alpha 1- and beta II-tubulin probes are likely to be conservative estimates of the underlying increase in alpha 1- and beta II-tubulin mRNA levels because sprouting SON neurons undergo significant hypertrophy. High levels of both alpha 1- and beta II-tubulin mRNAs were also seen in surviving axotomized SON neurons ipsilateral to the hypothalamic lesion. We conclude that the pattern of regulation of alpha 1- and beta II-tubulin mRNAs in CNS neurons which are capable of supporting new axonal growth includes three elements: maintenance of significant basal alpha 1- and beta II-tubulin mRNA pools in mature neurons, rapid increases in the pool size of the mRNAs following stimulation of collateral sprouting, and sustained elevation of mRNA levels during the period of axonal sprouting.