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S J Vannucci

Publications and source records attributed to S J Vannucci.

At least 19 recordsLinked to original sources
PubMed2003

Molecular characterization and partial cDNA cloning of facilitative glucose transporters expressed in human articular chondrocytes; stimulation of 2-deoxyglucose uptake by IGF-I and elevated MMP-2 secretion by glucose deprivation.

OBJECTIVE: Recent evidence suggests that human chondrocytes express several facilitative glucose transporter (GLUT) isoforms and also that 2-deoxyglucose transport is accelerated by cytokine stimulation. The aim of the present investigation was to determine if human articular chondrocytes express any of the recently identified members of the GLUT/SLC2A gene family and to examine the effects of endocrine factors, such as insulin and IGF-I on the capacity of human chondrocytes for transporting 2-deoxyglucose. DESIGN/METHODS: PCR, cloning and immunohistochemistry were employed to study the expression of GLUT/SLC2A transporters in normal human articular cartilage. The uptake of 2-deoxyglucose was examined in monolayer cultured immortalized human chondrocytes following stimulation with TNF-alpha, insulin and IGF-I. Levels of MMP-2 were assessed by gelatin zymography following glucose deprivation of alginate cultures. RESULTS: Using PCR we detected transcripts for eight glucose transporter isoforms (GLUTs 1, 3, 6, 8, 9, 10, 11 and 12) and for a fructose transporter (GLUT5) in human articular cartilage. Expression of GLUT1, GLUT3 and GLUT9 proteins in normal human articular cartilage was confirmed by immunohistochemistry. The uptake of 2-deoxyglucose was dependent on time and temperature, inhibited by cytochalasin B and phloretin, and significantly accelerated in chondrocyte cultures stimulated with IGF-I. However, 2-deoxyglucose uptake was unaffected by short and long-term insulin treatment, which ruled out a functional role for insulin-sensitive GLUT4-mediated glucose transport. Furthermore, secretion of MMP-2 was increased in alginate cultures deprived of glucose. CONCLUSIONS: The data supports a critical role for glucose transport and metabolism in the synthesis and degradation of cartilage.

Blotting, Western↗
PubMed2002

Differential effects of hypoxia-ischemia on subunit expression and tyrosine phosphorylation of the NMDA receptor in 7- and 21-day-old rats.

The effect of cerebral hypoxia-ischemia (HI) on levels and tyrosine phosphorylation of the NMDA receptor was examined in 7- (P7) and 21 (P21)-day-old rats. Unilateral HI was administered by ligation of the right common carotid artery and exposure to an atmosphere of 8% O2/92% N2 for 2 (P7) or 1.5 (P21) h. This duration of HI produces significant infarction in nearly all of the survivors with damage being largely restricted to the cortex, striatum, and hippocampus of the hemisphere ipsilateral to the carotid artery ligation. NR2A levels in the right hemisphere of P7 pups were markedly reduced after 24 h of recovery, while NR1 and NR2B remained unchanged. In contrast, NR2B, but not NR2A, was reduced after HI at P21. At both ages, HI resulted in a transient increase in tyrosine phosphorylation of a number of forebrain proteins that peaked between 1 and 6 h of recovery. At both P7 and P21, tyrosine phosphorylation of NR2B was enhanced 1 h after HI and had returned to basal levels by 24 h. HI induced an increase in tyrosine phosphorylation of NR2A in 21 day, but not in 7-day-old animals. The differential effects of HI on the NMDA receptor at different post-natal ages may contribute to changing sensitivity to hypoxia-ischemia.

Age Factors↗
PubMed2002

Glucose transport and metabolism in chondrocytes: a key to understanding chondrogenesis, skeletal development and cartilage degradation in osteoarthritis.

Despite the recognition that degenerative cartilage disorders like osteoarthritis (OA) and osteochondritis dissecans (OCD) may have nutritional abnormalities at the root of their pathogenesis, balanced dietary supplementation programs have played a secondary role in their management. This review emphasizes the importance and role of nutritional factors such as glucose and glucose-derived sugars (i.e. glucosamine sulfate and vitamin C) in the development, maintenance, repair, and remodeling of cartilage. Chondrocytes, the cells of cartilage, consume glucose as a primary substrate for ATP production in glycolysis and utilize glucosamine sulfate and other sulfated sugars as structural components for extracellular matrix synthesis and are dependent on hexose uptake and delivery to metabolic and biosynthetic pools. Data from several laboratories suggests that chondrocytes express multiple isoforms of the GLUT/SLC2A family of glucose/polyol transporters. These facilitative glucose transporter proteins are expressed in a tissue and cell-specific manner, exhibit distinct kinetic properties, and are developmentally regulated. They may also be regulated by endocrine factors like insulin and insulin-like growth factor I (IGF-I) and cytokines such as interleukin 1 beta (IL-1 beta) and tumour necrosis factor alpha (TNF-alpha). Recent studies suggest that degeneration of cartilage may be triggered by metabolic disorders of glucose balance and that OA occurs coincident with metabolic disease, endocrine dysfunction and diabetes mellitus. Based on these metabolic, endocrine and developmental considerations we present a novel hypothesis regarding the role of glucose transport and metabolism in cartilage physiology and pathophysiology and speculate that supplementation with sugar-derived vitamins and nutraceuticals may benefit patients with degenerative joint disorders.

Animals↗
PubMed2001

Intracellular calcium accumulation during the evolution of hypoxic-ischemic brain damage in the immature rat.

An excessive intracellular accumulation of calcium (Ca2+) in neurons and glia has been proposed to represent a major 'final common pathway' for cell death arising from hypoxia-ischemia. To clarify the role of altered calcium flux into the perinatal brain undergoing hypoxic-ischemic damage, 7-day postnatal rats underwent unilateral common carotid artery ligation followed by systemic hypoxia with 8% oxygen. This insult is known to produce brain damage in the form of selective neuronal death or infarction largely limited to the cerebral hemisphere ipsilateral to the arterial occlusion. Either prior to or following hypoxia-ischemia, the rat pups received a s.c. injection of 45CaCl2, and specimens of blood, cerebrospinal fluid (CSF), and brain were obtained for isotopic measurements and the calculation of the extent of brain intracellular radioactivity. During hypoxia-ischemia, there was a modest increase in intracellular Ca2+ radioactivity (+28-47%) in both cerebral hemispheres only after 2 h of hypoxia-ischemia. During recovery from 2 h of hypoxia-ischemia, intracellular Ca2+ accumulated progressively only in the ipsilateral cerebral hemisphere for up to 24 h, during which interval intracellular Ca2+ decreased in the contralateral hemisphere. No such progressive accumulation was noted during recovery in animals previously exposed to only 1 h of hypoxia-ischemia. The results suggest that a disruption of intracellular Ca2+ homeostasis is a major contributing factor in the evolution of perinatal hypoxic-ischemic brain damage. Ca2+ accumulation is a relatively modest and late event during the hypoxic-ischemic phase, and a progressive overload occurs during the recovery phase only if infarction occurs. The question remains as to whether or not the intracellular Ca2+ overload occurring during recovery is a contributor to or a consequence of the ultimate brain damage.

Animals↗
PubMed2001

Glucose transporter asymmetries in the bovine blood-brain barrier.

The transport of glucose across the mammalian blood-brain barrier is mediated by the GLUT1 glucose transporter, which is concentrated in the endothelial cells of the cerebral microvessels. Several studies supported an asymmetric distribution of GLUT1 protein between the luminal and abluminal membranes (1:4) with a significant proportion of intracellular transporters. In this study we investigated the activity and concentration of GLUT1 in isolated luminal and abluminal membrane fractions of bovine brain endothelial cells. Glucose transport activity and glucose transporter concentration, as determined by cytochalasin B binding, were 2-fold greater in the luminal than in the abluminal membranes. In contrast, Western blot analysis using a rabbit polyclonal antibody raised against the C-terminal 20 amino acids of GLUT1 indicated a 1:5 luminal:abluminal distribution. Western blot analysis with antibodies raised against either the intracellular loop of GLUT1 or the purified erythrocyte protein exhibited luminal:abluminal ratios of 1:1. A similar ratio was observed when the luminal and abluminal fractions were exposed to the 2-N-4[(3)H](1-azi-2,2,2,-trifluoroethyl)benzoxyl-1,3-bis-(d-mannos-4-yloxyl)-2-propylamine ([(3)H]ATB-BMPA) photoaffinity label. These observations suggest that either an additional glucose transporter isoform is present in the luminal membrane of the bovine blood-brain barrier or the C-terminal epitope of GLUT1 is "masked" in the luminal membrane but not in the abluminal membranes.

Affinity Labels↗
PubMed2001

Hypoglycemic brain injury.

Hypoglycemia frequently occurs in newborn infants who previously have suffered asphyxia, who are offspring of diabetic mothers, or who are low birthweight for gestational age (IUGR). Many infants who are hypoglycemic do not exhibit clinical manifestations, while others are symptomatic and at risk for the occurrence of permanent brain damage. This review emphasizes the clinical, neuropathologic, and neuro-imaging features of hypoglycemia in newborn infants, especially those who are symptomatic. Neurologic morbidity occurs particularly in those infants who have suffered severe, protracted, or recurrent symptomatic hypoglycemia. Experimental observations emphasize the resistance of the immature brain to the damaging effect of hypoglycemia; such resistance occurs as a consequence of compensatory increases in cerebral blood flow, lower energy requirements, higher endogenous carbohydrate stores, and an ability to incorporate and consume alternative organic substrates to spare glucose for energy production. Hypoglycemia combined with hypoxia-ischemia (asphyxia) is more deleterious to the immature brain than either condition alone.

Brain Injuries↗
PubMed2001

Experimental stroke in the female diabetic, db/db, mouse.

Diabetic hyperglycemia increases brain damage after cerebral ischemia in animals and humans, although the underlying mechanisms remain unclear. Gender-linked differences in ischemic tolerance have been described but have not been studied in the context of diabetes. In the current study, we used a model of unilateral common carotid artery ligation, combined with systemic hypoxia, to study the effects of diabetes and gender on hypoxic-ischemic (HI) brain damage in the genetic model of Type II diabetes, the db/db, mouse. Male and female, control and db/db, mice were subjected to right common carotid artery ligation followed by varying periods of hypoxia (8% oxygen/92% nitrogen) to assess mortality, infarct volume, and tissue damage by light microscopic techniques. End-ischemic regional cerebral blood flow (CBF) was determined using [14C] iodoantipyrine autoradiography. Glycolytic and high energy phosphate compounds were measured in blood and brain by enzymatic and fluorometric techniques. Gender and diabetes had significant effects on mortality from HI and extent of brain damage in the survivors. Female mice were more resistant than their male counterparts, such that the severity (mortality and infarction size) in the male diabetics > female diabetics - male controls > female controls. Endischemic CBF and depletion of cerebral high energy reserves were comparable among all groups. Surprisingly, female diabetic mice were more hyperglycemic and demonstrated a greater prolonged lactacidosis than the males; however, they were more resistant to damage. The results suggest a unique pathophysiology of hypoxia-ischemia in the female diabetic brain.

Animals↗
PubMed2001

Delayed cerebral atrophy following moderate hypoxia-ischemia in the immature rat.

Hypoxia-ischemia (H/I) damages cells in the immature brain and interferes with subsequent brain development; the extent of the damage has been related to the severity, or duration, of the initial insult. This study examined the effects of both severe and moderate duration of H/I on the evolution of damage through 8 weeks of recovery. Seven-day-old rat pups were subjected to either 75 min or 2 h of 8% oxygen following a unilateral carotid artery ligation. Evaluation of brain damage included morphometric analysis of hemispheric diameter at 2, 4, and 8 weeks of recovery, and hematoxylin and eosin for evaluation of pathology at 8 weeks. Two hours of H/I produced severe infarction in the ipsilateral hemisphere in the majority of the survivors, apparent by 2 weeks of recovery with no change at 4 or 8 weeks. In marked contrast, 75 min of H/I produced no significant damage during the initial 2 weeks of recovery but resulted in progressive cerebral atrophy with delayed infarction such that the extent of damage at 8 weeks was not different from the 2-hour group. Thus, even a mild-moderate ischemic insult to the perinatal brain establishes a vulnerable region which ultimately dies without intervention.

Animals↗
PubMed2001

Hypoxia/ischemia depletes the rat perinatal subventricular zone of oligodendrocyte progenitors and neural stem cells.

Cerebral hypoxia/ischemia of the newborn has a frequency of 4/1,000 births and remains a major cause of cerebral palsy, epilepsy, and mental retardation. Despite progress in understanding the pathogenesis of hypoxic-ischemic injury, the data are incomplete regarding the mechanisms leading to permanent brain injury. Here we tested the hypothesis that cerebral hypoxia/ischemia damages stem/progenitor cells in the subventricular zone (SVZ), resulting in a permanent depletion of oligodendrocytes. We used a widely accepted rat model and examined animals at recovery intervals ranging from 4 h to 3 weeks. Within hours after the hypoxic-ischemic insult 20% of the total cells were deleted from the SVZ. The residual damaged cells appeared necrotic. During 48 h of recovery deaths accumulated; however, these later deaths were predominantly apoptotic. Many apoptotic SVZ cells stained with a marker for immature oligodendrocytes. At 3 weeks survival, the SVZ was smaller and markedly less cellular, and it contained less than 1/4 the normal complement of neural stem cells. The corresponding subcortical white matter was dysmyelinated, relatively devoid of oligodendrocytes and enriched in astrocytes. We conclude that neural stem cells and oligodendrocyte progenitors in the SVZ are vulnerable to hypoxia/ischemia. Consequently, the developmental production of oligodendrocytes is compromised and regeneration of damaged white matter oligodendrocytes does not occur resulting in failed regeneration of CNS myelin in periventricular loci. The resulting dysgenesis of the brain that occurs subsequent to perinatal hypoxic/ischemic injury may contribute to the cognitive and motor dysfunction that results from asphyxia of the newborn.

Animals↗
PubMed2001

Effect of extreme hypercapnia on hypoxic-ischemic brain damage in the immature rat.

To ascertain the effect of extreme hypercapnia on perinatal hypoxic-ischemic brain damage, 7-d-postnatal rats were exposed to unilateral common carotid artery occlusion followed by hypoxia with 8% oxygen combined with 3, 12, or 15% carbon dioxide (CO2) for 2 h at 37 degrees C. Survivors underwent neuropathologic examination at 30 d of postnatal age, and their brains were characterized as follows: 0 = normal; 1 = mild atrophy; 2 = moderate atrophy; 3 = cystic infarct with external dimensions <3 mm; and 4 = cystic infarct with external dimensions >3 mm. The width of the cerebral hemisphere ipsilateral to the carotid artery occlusion also was determined on a posterior coronal section and compared with that of the contralateral hemisphere to ascertain the severity of cerebral atrophy/cavitation. CO2 tensions averaged 5.08, 11.1, and 13.2 kPa in the 3, 12, and 15% CO2-exposed animals, respectively, during hypoxia-ischemia (HI). Neuropathologic results showed that immature rats exposed to 3 and 12% CO2 had similar severities of brain damage. In contrast, rat pups exposed to HI combined with 15% CO2 were significantly more brain damaged than littermates exposed to 3% CO2. Specifically, eight of 14 animals exposed to 15% CO2 showed cystic infarcts (grades 3 and 4), whereas none of 14 littermates exposed to 3% CO2 developed cystic infarcts (p < 0.01). Analyses of coronal width ratios at each CO2 exposure provided results comparable with those of the gross neuropathology scores. Cerebral blood flow (CBF), measured at 90 min of HI, was lowest in those immature rats exposed to 15% CO2 compared with control (p = 0.04), with higher values in those rat pups exposed to 3 and 12% CO2. The findings indicate that 7-d-postnatal rats exposed to HI with superimposed 12% CO2 are neither less nor more brain damaged than littermates exposed to 3% CO(2) (normocapnia). In contrast, animals exposed to 15% CO2 are the most brain damaged of the three groups. Presumably, extreme hypercapnia produces more severe cardiovascular depression than is seen in animals subjected to lesser degrees of hypercapnia; the cardiovascular depression, in turn, leads to greater cerebral ischemia and ultimate brain damage.

Animals↗
PubMed2000

Glucose metabolism in the developing brain.

As in adults, glucose is the predominant cerebral energy fuel for the fetus and newborn. Studies in experimental animals and humans indicate that cerebral glucose utilization initially is low and increases with maturation with increasing regional heterogeneity. The increases in cerebral glucose utilization with advancing age occurs as a consequence of increasing functional activity and cerebral energy demands. The levels of expression of the 2 primary facilitative glucose transporter proteins in brain, GLUT1 (blood-brain barrier and glia) and GLUT3 (neuronal), display a similar maturational pattern. Alternate cerebral energy fuels, specifically the ketone bodies and lactate, can substitute for glucose, especially during hypoglycemia, thereby protecting the immature brain from potential untoward effects of hypoglycemia. Unlike adults, glucose supplementation during hypoxia-ischemia is protective in the immature brain, whereas hypoglycemia is deleterious. Accordingly, glucose plays a critical role in the developing brain, not only as the primary substrate for energy production but also to allow for normal biosynthetic processes to proceed.

Aging↗
PubMed2000

Cerebral glucose utilization and glucose transporter expression: response to water deprivation and restoration.

The relationship between local rates of cerebral glucose utilization (ICMRglc) and glucose transporter expression was examined during physiologic activation of the hypothalamoneurohypophysial system. Three days of water deprivation, which is known to activate the hypothalamoneurohypophysial system, resulted in increased ICMRglc and increased concentrations of GLUT1 and GLUT3 in the neurohypophysis; mRNA levels of GLUT1 and GLUT3 were decreased and increased, respectively. Water deprivation also increased ICMRglc in the hypothalamic supraoptic and paraventricular nuclei; mRNA levels of GLUT1 and GLUT3 appeared to increase in these nuclei, but the changes did not achieve statistical significance. Restoration of water for 3 to 7 days reversed all observed changes in GLUT expression (protein and mRNA): restoration of water also reversed changes in ICMRglc in both the neurohypophysis and the hypothalamic nuclei. These results indicate that under conditions of neural activation and recovery, changes in ICMRglc and the levels of GLUT1 and GLUT3 are temporally correlated in the neurohypophysis and raise the possibility that GLUT1 and GLUT3 transporter expression may be regulated by chronic changes in functional activity. In addition, increases in the expression of GLUT5 mRNA in the neurohypophysis after dehydration provide evidence for involvement of microglial activation.

Animals↗
PubMed2000

Prenatal expression of the GLUT4 glucose transporter in the mouse.

The GLUT4 glucose transporter is primarily expressed in skeletal muscle, heart and adipose tissue, where its expression is postnatal, coincident with the acquisition of insulin-regulated glucose transport. In muscle, contraction also regulates GLUT4 activity in the postnatal animal. Here we demonstrate that GLUT4 is expressed in the developing mouse embryo with specific tissue and spatiotemporal patterns. From embryonic day 9 (E9; E1 = day of copulation plug) to postnatal day 70 (P70), mice were analyzed for GLUT4 mRNA and protein expression by in situ hybridization, immunohistochemistry and immunoblot. Specificity was confirmed with sense riboprobe hybridization and peptide competition, respectively. At E9, GLUT4 was detected in the cranial neural folds in the outer (mantle) layer of the neuroepithelium. At E10, expression was present throughout the developing heart and was prominent in the endocardial cushions through E12. At E10-12, GLUT4 was also prominent in craniofacial mesenchyme. GLUT4 expression in cartilage and bone was evident at E12 and was maintained throughout early postnatal life. GLUT4 was apparent throughout embryonic development in the ventricular epithelium, choroid plexus and in the developing cerebellum. At birth, cardiac expression was reduced and GLUT4 was most evident in cartilage, bone and specific brain regions. In the latter, GLUT4 expression was most evident in the cerebellum, specifically in the external granular layer through P7 and in the internal granular layer thereafter. Maximal GLUT4 protein levels in the cerebellum were measured between P14 and P21 and were reduced in the adult brain. These findings suggest that GLUT4-mediated glucose transport may play important roles during development of the brain and nonneuronal tissues in the mouse embryo.

Animals↗
PubMed1999

CSF glutamate during hypoxia-ischemia in the immature rat.

Cerebrospinal fluid (CSF) glutamate was measured prior to and during the course of cerebral hypoxia-ischemia in the immature rat to estimate its concentration in the extracellular fluid (ECF). A preliminary experiment was conducted using [14C]glutamate injections into immature rat brain, which showed that equilibration between ECF and CSF occurred within 10 min. Seven-day postnatal rats underwent unilateral common carotid artery ligation followed by hypoxia with 8% oxygen for up to 2 h. Brain damage, in the form of selective neuronal necrosis or apoptosis, commences after 60 min, while infarction commences after 90 min of hypoxia-ischemia. During the course of hypoxia-ischemia, CSF was obtained from the cisterna magna and analyzed for glutamate. No statistically significant increases in CSF glutamate occurred until 105 min, at which time the concentration was 240% of control (20 micromol/l). By 120 min, CSF glutamate had increased over twofold above the control value. In rat pups exposed to 1 h of hypoxia-ischemia, no increases in CSF glutamate occurred for up to 6 h of recovery. In animals exposed to 2 h of hypoxia-ischemia, CSF glutamate decreased to the control value by 1 h of recovery, with a secondary rise at 6 h. Accordingly, the increase in CSF, and presumably ECF, glutamate is a late event, which better corresponds temporally to cerebral infarction than to selective neuronal death. The results suggest that glutamate excitotoxicity, although involved in the occurrence of infarction, neither causes or contributes to selected neuronal death. The secondary elevation in CSF glutamate at 6 h of recovery from 2 h of hypoxia-ischemia occurs coincident with the onset of tissue necrosis, seen histologically.

Animals↗
PubMed1999

Rat model of perinatal hypoxic-ischemic brain damage.

To gain insights into the pathogenesis and management of perinatal hypoxic-ischemic brain damage, the authors have used an immature rat model which they developed many years ago. The model entails ligation of one common carotid artery followed thereafter by systemic hypoxia. The insult produces permanent hypoxic-ischemic brain damage limited to the cerebral hemisphere ipsilateral to the carotid artery occlusion. The mini-review describes recently accomplished research pertaining to the use of the immature rat model, specifically, investigations involving energy metabolism, glucose transporter proteins, free radical injury, and seizures superimposed upon cerebral hypoxia-ischemia. Future research will focus on molecular mechanisms of neuronal injury with a continuing focus on therapeutic strategies to prevent or minimize hypoxic-ischemic brain damage.

Animals↗
PubMed1999

Blood-brain barrier glucose transporter: effects of hypo- and hyperglycemia revisited.

The transport of glucose across the blood-brain barrier (BBB) is mediated by the high molecular mass (55-kDa) isoform of the GLUT1 glucose transporter protein. In this study we have utilized the tritiated, impermeant photolabel 2-N-[4-(1 -azi-2,2,2-trifluoroethyl)[2-3H]propyl]-1,3-bis(D-mannose-4-ylo xy)-2-propylamine to develop a technique to specifically measure the concentration of GLUT1 glucose transporters on the luminal surface of the endothelial cells of the BBB. We have combined this methodology with measurements of BBB glucose transport and immunoblot analysis of isolated brain microvessels for labeled luminal GLUT1 and total GLUT1 to reevaluate the effects of chronic hypoglycemia and diabetic hyperglycemia on transendothelial glucose transport in the rat. Hypoglycemia was induced with continuous-release insulin pellets (6 U/day) for a 12- to 14-day duration; diabetes was induced by streptozotocin (65 mg/kg i.p.) for a 14- to 21-day duration. Hypoglycemia resulted in 25-45% increases in regional BBB permeability-surface area (PA) values for D-[14C]glucose uptake, when measured at identical glucose concentration using the in situ brain perfusion technique. Similarly, there was a 23+/-4% increase in total GLUT1/mg of microvessel protein and a 52+/-13% increase in luminal GLUT1 in hypoglycemic animals, suggesting that both increased GLUT1 synthesis and a redistribution to favor luminal transporters account for the enhanced uptake. A corresponding (twofold) increase in cortical GLUT1 mRNA was observed by in situ hybridization. In contrast, no significant changes were observed in regional brain glucose uptake PA, total microvessel 55-kDa GLUT1, or luminal GLUT1 concentrations in hyperglycemic rats. There was, however, a 30-40% increase in total cortical GLUT1 mRNA expression, with a 96% increase in the microvessels. Neither condition altered the levels of GLUT3 mRNA or protein expression. These results show that hypoglycemia, but not hyperglycemia, alters glucose transport activity at the BBB and that these changes in transport activity result from both an overall increase in total BBB GLUT1 and an increased transporter concentration at the luminal surface.

Affinity Labels↗