Global differential expression of genes located in the Down Syndrome Critical Region in normal human brain

Background: The information of gene expression obtained from databases, have made possible the extraction and analysis of data related with several molecular processes involving not only in brain homeostasis but its disruption in some neuropathologies; principally in Down syndrome and the Alzheimer disease. Objective: To correlate the levels of transcription of 19 genes located in the Down Syndrome Critical Region (DSCR) with their expression in several substructures of normal human brain. Methods: There were obtained expression profiles of 19 DSCR genes in 42 brain substructures, from gene expression values available at the database of the human brain of the Brain Atlas of the Allen Institute for Brain Sciences", (http://human.brain-map.org/). The co-expression patterns of DSCR genes in brain were calculated by using multivariate statistical methods. Results: Highest levels of gene expression were registered at caudate nucleus, nucleus accumbens and putamen among central areas of cerebral cortex. Increased expression levels of RCAN1 that encode by a protein involved in signal transduction process of the CNS were recorded for PCP4 that participates in the binding to calmodulin and TTC3; a protein that is associated with differentiation of neurons. That previously idenjpgied brain structures play a crucial role in the learning process, in different class of memory and in motor skills. Conclusion: The precise regulation of DSCR gene expression is crucial to maintain the brain homeostasis, especially in those areas with high levels of gene expression associated with a remarkable process of learning and cognition.

Global differential expression of genes located in the Down Syndrome Critical Region in normal human brain

BACKGROUND

The information of gene expression obtained from databases, have made possible the extraction and analysis of data related with several molecular processes involving not only in brain homeostasis but its disruption in some neuropathologies; principally in Down syndrome and the Alzheimer disease.

OBJECTIVE

To correlate the levels of transcription of 19 genes located in the Down Syndrome Critical Region (DSCR) with their expression in several substructures of normal human brain.

METHODS

There were obtained expression profiles of 19 DSCR genes in 42 brain substructures, from gene expression values available at the database of the human brain of the Brain Atlas of the Allen Institute for Brain Sciences", (http://human.brain-map.org/). The co-expression patterns of DSCR genes in brain were calculated by using multivariate statistical methods.

RESULTS

Highest levels of gene expression were registered at caudate nucleus, nucleus accumbens and putamen among central areas of cerebral cortex. Increased expression levels of RCAN1 that encode by a protein involved in signal transduction process of the CNS were recorded for PCP4 that participates in the binding to calmodulin and TTC3; a protein that is associated with differentiation of neurons. That previously identified brain structures play a crucial role in the learning process, in different class of memory and in motor skills.

CONCLUSION

The precise regulation of DSCR gene expression is crucial to maintain the brain homeostasis, especially in those areas with high levels of gene expression associated with a remarkable process of learning and cognition.

Lessons from an outbreak of metallo-β-lactamase-producing Klebsiella oxytoca in an intensive care unit: the importance of time at risk and combination therapy

BACKGROUND

Outbreaks of nosocomial infection due to carbapenem-resistant Enterobacteriaceae (CRE), mostly Klebsiella spp., have become a worldwide phenomenon.

AIM

To investigate the risk factors for the acquisition of clonal multidrug-resistant Klebsiella oxytoca (MDRKO) producing the metallo-β-lactamase IMP-8 and hyperproducing chromosomal OXY-2 β-lactamase during a well-characterized outbreak, and to describe the clinical features of infections due to MDRKO.

METHODS

A four-wave outbreak due to MDRKO occurred in the intensive care unit of a Spanish hospital between 2009 and 2011. The risk factors for acquisition of MDRKO during waves 1 and 2 (in which colonized patients served as the main reservoir for the epidemic strain) were analysed using a case-control study by Cox regression and logistic regression analysis. Clinical data and treatments of patients infected with MDRKO were also analysed.

FINDINGS

For the study of risk factors, 26 cases and 45 controls were studied. None of the variables studied in the Cox regression analysis showed an association with MDRKO acquisition; time at risk was the only associated variable by logistic regression analysis. Colonization pressure was not associated with earlier acquisition. Overall, 14 patients were infected with MDRKO; ventilator-associated pneumonia (seven patients) was the most frequent type of infection. Monotherapy tended to be associated with higher mortality than combination therapy [60% (3/5) vs 16.6% (1/6); P = 0.07].

CONCLUSIONS

Time at risk was the most significant risk determinant for the acquisition of carbapenem-resistant Enterobacteriaceae (CRE) in this epidemiological context and should be included in any study of risk factors for the acquisition of multidrug-resistant bacteria. Combination therapy may be superior to monotherapy for the treatment of CRE infections.

Taste compounds in chorizo and their changes during ripening

Taste compounds in chorizo-a dry fermented sausage-prepared by both traditional and industrial methods, i.e. D- and L-lactic acid, acetic acid, free amino acids and ATP derivatives, were analysed. Industrial chorizo contained larger amounts of D-lactic, L-lactic and acetic acids, several amino acids (e.g. γ-aminobutyric acid, phenylalanine) and hypoxanthine (Hx) than the traditional one (p < 0.05). The variations in taste compounds during the ripening of chorizo were tracked. D-Lactic and acetic acid increased, as well as most of the amino acids. ATP derivatives showed characteristic changes, IMP decreased on the first day and inosine (Ino) changed gradually to Hx during ripening. The taste compounds contents of garlic and paprika were studied. There was an important contribution of asparagine from spices to the initial mixture of sausage.

Therapeutic effect of an altered peptide ligand derived from heat-shock protein 60 by suppressing of inflammatory cytokines secretion in two animal models of rheumatoid arthritis

Rheumatoid arthritis is a systemic autoimmune disease mediated by T cells. Productive engagement of T cell receptors by major histocompatibility complex-peptide leads to proliferation, differentiation and the definition of effector functions. Altered peptide ligands (APL) generated by amino acid substitutions in the antigenic peptide have diverse effects on T cell response. We predicted a novel T cell epitope from human heat-shock protein 60, an autoantigen involved in the pathogenesis of rheumatoid arthritis. Three APLs were designed from this epitope and it was demonstrated that these peptides induce the activation of T cells through their ability to modify cell cycle phase's distribution of CD4+T cells from RA patients. Also, IL-17, TNF-α and IL-10 levels were determined in PBMC from these patients. Unlike the wild-type peptide and the other two APLs, APL2 increased the IL-10 level and suppressed IL-17 secretion in these assays. Therapeutic effect of this APL in adjuvant arthritis (AA) and collagen-induced arthritis (CIA) models was also evaluated. Clinical score, histopathology, inflammatory and regulatory cytokine concentration were monitored in the animals. APL2 efficiently inhibited the progression of AA and CIA with a significant reduction of the clinical and histopathologic score. Therapeutic effect of APL2 on CIA was similar to that obtained with MTX; the standard treatment for RA. This effect was associated with a decrease of TNF-α and IL-17 levels. These results suggest that the therapeutic effect of APL2 is mediated in part by down-regulation of inflammatory cytokines and support the potential use of APL2 as a therapeutic drug in RA patients.

FISIOLOGIA CROMOSOMICA, SINTESIS DE PROTEINAS Y ACIDO RIBONUCLEICO EN LAS GLANDULAS SALIVARES DE Rhynchosciara millery DIPTERA (Sciaridac)

la actividad de síntesis de MIMA de las glándulas salivares es baja. fué posible determinar varias formas polipeptídicas. til polipéptido de Mr 2S Kd se cor­relacionó con el producto de traducción del puff de UN A H-2. La banda proirira de 18 Kd se determinó como el producto gruir o del piiff dr DNA - O - .'5. box resultados obtenidos, muestran rjne la sintesis de TINA y proteínas en glándulas salivares esta especie son eventos moleculares controlados a nivel de desarrollo glandular.

[Genome epidemiology and tropical spastic paraparesis associated with human T-cell lymphotropic virus type 1]

OBJECTIVE

Characterize the genomic environment of the sequences adjacent to human T-cell lymphotropic virus type 1 (HTLV-1) in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in different regions of Colombia and Japan.

METHODS

A total of 71 recombinant clones with human genome sequences adjacent to 5' LTR in patients with HAM/TSP were compared to the Genome Browser and GenBank databases. Sixteen structural and compositional genome variables were identified, and statistical analysis was conducted in the R computer program, version 2.8.1, in a 0.5 Mb window.

RESULTS

A total of 43.0% of the proviruses were located in the group C chromosomes; 74% of the sequences were located in the telomeric and subtelomeric regions (P < 0.05). A cluster analysis was used to establish the hierarchical relations between the genome characteristics included in the study. The analysis of principal components identified the components that defined the preferred genome environments for proviral integration in cases of HAM/TSP.

CONCLUSIONS

HTLV-1 was integrated more often in chromatin regions rich in CpG islands with a high density of genes and LINE type repetitions, and DNA transposons which, overall, would form the genomic environments targeted for integration. This new scenario will promote substantial changes in the field of public health and in epidemiological management of infectious diseases. It will also foster the development of powerful tools for increasing the efficiency of epidemiological surveillance.

Human T-Lymphotropic Virus (HTLV) Type I in vivo Integration in Oral Keratinocytes

Although the infection of HTLV-1 to cell components of the mouth have been previously reported, there was not until this report, a detailed study to show the characteristics of such infection. From 14 Tropical Spastic Paraparesis/HTLV-1-Associated Myelopathy (HAM/TSP) patients and 11 asymptomatic carrier individuals (AC) coming from HTLV-1 endemic areas of southwest Pacific of Colombia, infected oral mucosa cells were primary cultured during five days. These cell cultures were immunophenotyped by dual color fluorescence cell assortment using different lymphocyte CD markers and also were immunohistochemically processed using a polyclonal anti-keratin antibody. Five days old primary cultures were characterized as oral keratinocytes, whose phenotype was CD3- /CD4-/CD8-/CD19-/CD14-/CD45-/A575-keratin+. From DNA extracted of primary cultures LTR, pol, env and tax HTLV-1 proviral DNA regions were differentially amplified by PCR showing proviral integration. Using poly A+ RNA obtained of these primary cultures, we amplify by RT-PCR cDNA of tax and pol in 57.14% (8/14) HAM/TSP patients and 27.28% (3/11) AC. Tax and pol poly A+ RNA were expressed only in those sIgA positive subjects. Our results showed that proviral integration and viral gene expression in oral keratinocytes are associated with a HTLV-1 specific local mucosal immune response only in those HTLV-1 infected individuals with detectable levels of sIgA in their oral fluids. Altogether the results gave strong evidence that oral mucosa infection would be parte of the systemic spreading of HTLV-1 infection.

[Clonal expansion and genomic characterization of the human T-cell lymphotropic virus type I during the integration process in adult T-cell leukemia/lymphoma]

INTRODUCTION

Although the integration of human T-cell lymphotropic virus type I into the T-cells is not a random process, the mechanistic details are not understood.

OBJECTIVES

The characteristics of the flanking host chromatin were evaluated at the integration sites in adult T-cell leukaemia/lymphoma (ATLL) patients infected with the virus.

MATERIALS AND METHODS

From seven leukemic Colombian patients positive for the human T-cell lymphotropic virus type I (HTLV-I), lymphocyte DNA samples were extracted and amplified by inverse polymerase chain reaction (IPCR). Clonal expansion and human genome nucleotide composition in an extension of 50 bp was determined. To establish the characteristics of the human genome flanking provirus, 61 IPCR sequences from Colombian and Japanese ATLL patients, were analyzed in silico to obtain insights about the genomic structure, functions and nature of associated chromatin.

RESULTS

The clonal expansion of cell clones was predominantly oligoclonal. From 61 IPCR sequences, 155 alignments with homology higher than 95% (e-value < 0.05) were screened. Seventy-five percent of those sequences corresponded to non coding elements that include repetitive and non-repetitive DNA. Fifty percent of the proviral integrations were associated with chromosomes of A and B groups. Viral DNA integration tended to favor exons of genes that replicated early, controlled the cell cycle, or were involved in signal transduction.

CONCLUSIONS

The results indicated that HTLV-I integration was preferentially directed towards genomic environments with high C:G content, and toward genes that replicate early, regulate cell cycle or involved with signal transduction.

[Autoimmune syndrome in the tropical spastic paraparesis/myelopathy associated with human T-lymphotropic virus infections]

INTRODUCTION

Previous reports have given evidence that in tropical spastic paraparesis (TSP)/human T-lymphotrophic virus (HTLV-I)-associated myelopathy (HAM), an autoimmune process occurs as part of its pathogenesis.

OBJECTIVE

The roles of autoimmunity and the molecular mimicry was evaluated in TSP/HAM patients.

MATERIALS AND METHODS

Plasma samples were characterized from patients in the Pacific coastal region of Colombia. Thirty-seven were identified as TSP/HAM, 10 were diagnosed with adult T-cell leukemia virus, 22 were asymptomatic carriers but seropositive for HTLV-I and 20 were seronegative and served as negative controls. Plasmatic levels of the following were determined: antinuclear antibody (ANA) levels, anticardiolipine-2 (ACL-2), interferon- (IFN-gamma) and interleukin-4 (IL-4). Using Western blot, the crossreactivity of the seropositive and seronegative samples was evaluated against proteins extracted from several central nervous system components of non infected Wistar rats. The HTLV-I seropositive plasmas were crossreacted with a monoclonal tax (LT4 anti-taxp40) from spinal cord neurons of non infected Wistar rats.

RESULTS

Of the TSP/HAM patients, 70.2% were reactive against ANA and 83.8% against ACL-2, in contrast with those ATL and asymptomatic seropositives subjects that were not reactive (P<0.001). Moreover, 70.3% had detectable levels of IFN and 43.2% had detectable IL-4. LT4 anti-taxp40 and plasma of TSP/HAM exhibited cross reactivity with a MW 33-35 kDa protein from the rat spinal cord nuclei.

CONCLUSION

Support was provided for the existence of an autoimmune syndrome mediated by molecular mimicry; the syndrome was responsible for some of the axonal degeneration observed in TSP/HAM patients.

[Construction of an adenoassociated, viral derived, expression vector to correct the genetic defect in Morquio A disease]

INTRODUCTION

Mucopolysaccharidosis IVA (Morquio A) is caused by a deficiency of N-acetylgalactosamine-6-sulphate-sulphatase, a lysosomal enzyme required for the stepwise degradation of keratan-sulfate and chondroitin-6-sulfate. A deficiency in this enzyme results in an accumulation of glycosaminoglycans in several tissues. Currently, no effective therapies exist and only supportive measures are used to treat some manifestations of the disease. An ideal therapy is one that can be administrated early in life, has low mortality, and leads to long-term expression of the enzyme. Gene therapy emerges as a potential alternative to correct the genetic defect in MPS IVA.

OBJECTIVE

Adenoassociated virus-derived expression vectors (AAV) were constructed to correct in vitro the enzyme deficiency in mucopolysaccharidosis IVA.

MATERIALS AND METHODS

Adenoasociated virus-derived vectors containing the human GALNS gene and driven by the citomegalivirus immedited-early promoter were constructed using a free-adenoviral protocol. HEK293 cells and human skin Morquio A fibroblasts were transfected with the recombinat vectors. Enzyme activity was measured in cells 24 and 48 hours post-transfection.

RESULTS

Free-adenovirus recombinant AAV vectors were obtained with titres up to 2.08x1010 capsids/mL. HEK293 cells and Morquio A fibroblasts transfected with vectors showed GALNS activity up to 3.05 nmoles/mg/h 48 hours post-transfection.

CONCLUSION

The AAV mediated the in vitro expression of GALNS enzyme in the transfected cells. These results are the first step towards a gene therapy alternative to Morquio A disease using adenoassociated virus-derived vectors.

Autoimmunity and molecular mimicry in tropical spastic paraparesis/human T-lymphotropic virus-associated myelopathy

Viruses share antigenic sites with normal host cell components, a phenomenon known as molecular mimicry. It has long been suggested that viral infections might trigger an autoimmune response by several mechanisms including molecular mimicry. More than 600 antiviral monoclonal antibodies generated against 11 different viruses have been reported to react with 3.5% of cells specific for uninfected mouse organs. The main pathological feature of tropical spastic paraparesis/human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (TSP/HAM) is a chronic inflammation of the spinal cord characterized by perivascular cuffing of mononuclear cells accompanied by parenchymal lymphocytic infiltration. We detected the presence of autoantibodies against a 98- to 100-kDa protein of in vitro cultured human astrocytes and a 33- to 35-kDa protein from normal human brain in the serum of HTLV-I-seropositive individuals. The two cell proteins exhibited molecular mimicry with HTLV-I gag and tax proteins in TSP/HAM patients, respectively. Furthermore, the location of 33- to 35-kDa protein cross-reaction correlated with the anatomical spinal cord areas (in the rat model) in which axonal damage has been reported in several cases of TSP/HAM patients. Our experimental evidence strongly suggests that the demyelinating process occurring in TSP/HAM may be mediated by molecular mimicry between domains of some viral proteins and normal cellular targets of the spinal cord sections involved in the neurodegeneration.

Concurrent cholangiocarcinoma, peritonitis, paratuberculosis, and aspergillosis in a goat

Images

Application of a spectrophotometric method for the determination of post-antibiotic effect and comparison with viable counts in agar

The post-antibiotic effects of gentamicin and ciprofloxacin at 1x, 2x and 4x MIC on Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 were studied using a spectrophotometric method and the classic method of viable counts on agar as a reference. Monitoring of the growth kinetics was carried out by viability counting on the plate every hour and by means of the optical density of the cultures measured by spectrophotometry at a wavelength of 450 nm. No statistically significant differences were found between the results obtained with the spectrophotometric method and the reference method. The former method was much quicker, much easier to use and to replicate.

Recurrence of the D409H mutation in Spanish Gaucher disease patients: description of a new homozygous patient and haplotype analysis

Gaucher disease results, in most patients, from mutations in the gene encoding glucocerebrosidase. Mutation D409H is the third most frequent in Spanish patients, accounting for 5.7% of all mutated alleles. This allele is associated mainly with the neurological forms of the disease. Recently, homozygosity for the D409H mutation has been associated with a particular phenotype, including specific cardiovascular symptoms. Here we report a second Spanish patient bearing the D409H/D409H genotype with a very early manifestation of the disease. The patient started enzyme replacement therapy at 3 months of age. A common origin for the Spanish D409H alleles was ruled out by haplotype analysis using an internal polymorphism of the glucocerebrosidase gene and two external microsatellite markers.

Broadly reactive antibodies against a gp120 V3 loop multi-epitope polypeptide neutralize different isolates of human immunodeficiency virus type 1 (HIV-1)

A gene encoding for a novel multi-epitope polypeptide (TAB4) was synthesized and expressed in Escherichia coli. The protein was composed of 15 amino acid fragments derived from the V3 loop of HIV-1 isolates MN, IIIB, RF, JY1, BRVA and LR150, joined by five-amino-acid linkers. Immunogenicity of TAB4 in rabbits was studied, and the antibody response against individual peptides investigated. TAB4 was shown to be immunogenic in Complete Freund's Adjuvant in a dose-dependent manner, and was able to elicit a humoral response against all V3 epitopes included on the protein. Sera from some of the animals were able to neutralize the replication of viral strain MN, and in one case IIIB, with moderate titers. Some sera also neutralized several Cuban clinical strains, isolated in peripheral blood mononuclear cells, after one round of amplification in MT4 cells.

[Bacteremias due to the Streptococcus milleri group. An analysis of 18 episodes]

OBJECTIVE

To study the epidemiological and clinical characteristics of bacteremia caused by Streptococcus milleri group streptococci (SMG).

METHODS

Prospective evaluation of all bacteremic episodes with clinical significance from 1990 to 1995 in two general hospitals. In this study all episodes caused by SMG were analyzed.

RESULTS

A total of 905 bacteremic episodes with clinical significance were detected; 18 (1.98%) were caused by SMG (0.16/1,000 admissions). The mean age of patients were 43 years and the male/female ratio 1.6. Seventeen patients (94.4%) had some underlying disease; nine patients had diabetes, four were parenteral drug abusers, and two had neoplasms. The most common sources of bacteremia were intraabdominal in four episodes (two liver abscesses, one subphrenic abscess and one pancreatic pseudocyst), cutaneous and/or soft tissues in four, surgical wound in two and respiratory in two; no source was identified in five episodes. Four episodes had a polymicrobial origin. In 13 isolates the identification was at species level (Streptococcus anginosus eight, Streptococcus intermedius four and Streptococcus constellatus one). All strains were susceptible to penicillin. Six patients (33.3%) required surgery. In ten episodes a favorable outcome was recorded, although four patients required surgery. The infection associated mortality rate was 31.2%. The mean age of deceased patients was higher than for cured patients (62.2 +/- 20.2 versus 35.3 +/- 20.3; p < 0.05).

CONCLUSIONS

SMB bacteremia is uncommon. It involved mainly diabetic patients or parenteral drug abusers, commonly with an intraabdominal suppurative source or in skin or soft tissues. The mortality rate was high despite surgery in one third of patients. Patients with advanced age had a poorer prognosis. All isolates investigated were susceptible to penicillin.

[Evolution of the sensitivity of Bacteroides group fragilis at the Sevilla University Hospital (1983-1987)]

The evolution of antimicrobial susceptibility of Bacteroides fragilis over a five year period is described. We have studied 30 selected strains isolated each year at the University Hospital of Sevilla (total: 150 strains). We did not find any resistant strain to chloramphenicol, metronidazole or imipenem. Resistance to piperacillin (8%) and cefoxitin (13%) remain constant over the study period. Resistance to cefmetazole, cefotaxime, mezlocillin, ofloxacin, clindamycin and moxalactam ranges from 24% to 37%. A rise in the percentage of resistant strains to ticarcillin (from 17% to 30%) and ceftizoxime (from 0% to 40%) was also seen during the study period. Bacteroides thetaiotaomicron was the overall more resistant species, and B. fragilis the more sensitive.

[Antimicrobial activity of ornidazole and 6 other antibiotics against anaerobic bacteria]

The antimicrobial susceptibility of 235 anaerobic bacterial strains to ornidazole, metronidazole, chloramphenicol, clindamycin, penicillin, cefoxitin and imipenem has been studied using agar-dilution technique. Ornidazole and metronidazole were active against 88.6% and 86% of gram-positive cocci. Overall, 99.1% of Bacteroides group fragilis, and 91.3% of non-fragilis Bacteroides were also sensitive to both drugs. We did not find any Clostridium perfringens resistant strain. Cefoxitin and penicillin showed good activity against all Clostridium perfringens strains, and also against 97.7% and 92.5% of gram-positive cocci. We found one single imipenem resistant strain among gram-positive bacteria. Bacteroides fragilis also showed sensitivity to penicillin (41.5%), cefoxitin (85.7%) and imipenem (97.1%). Clindamycin was active against Clostridium perfringens (90.9%), gram-positive cocci (86.7%) and imipenem (68.6%). Chloramphenicol showed good activity against Clostridium perfringens (100%), gram-positive cocci (95.5%) and Bacteroides spp. (99.4%). Our results showed an overall good activity of all the seven drugs tested against anaerobic gram-positive microorganisms. Of notice, we found a good activity of chloramphenicol, imipenem, metronidazole and ornidazole against Bacteroides spp.

[Cerebral infarct in a young adult, as the presenting form of myeloencephalopathic syndrome with lactic acidosis and cerebral ischemia]

We report a 26-year-old male who developed aphasia due to an ischemic cerebral infarction caused by MELAS (myoencephalophatic syndrome with lactic acidosis and cerebral ischemia). The most common causes of cerebral infarction in young patients were ruled out by laboratory investigations. The diagnosis of MELAS was suspected on the basis of past history of epilepsy, migraine and progressive sensory deafness, and increased resting blood lactic acid. Cerebral computed tomography showed bilateral caudate-putamen-pallidal calcification and nuclear magnetic resonance scan disclosed a left ischemic parietal-temporal-occipital infarction. The diagnosis was confirmed by muscular biopsy, which was characteristic of mitochondrial myopathy showing "red disarrayed" fibers in the histologic modified trichromic Gomori stain. Our patient showed that MELAS should be considered in young adults with cerebral infarction. The diagnosis should initially be suspected on a clinical basis, and confirmed by the presence of "red disarrayed" fibers with modified trichromic Gomori stain histologic muscle study.

Effects of glycerol and glucose on the kinetics of glycerol utilization by adipose tissue in the rat

To study the kinetics of glycerol utilization by adipose tissue in vitro as function of the concentrations of both glycerol and glucose in the incubation media, pieces of epididymal fat pad from fed rats were incubated for different times in Krebs Ringer bicarbonate supplemented with 1-14C-glycerol and purified albumin. An increase in the concentration of glycerol in the medium produces a decrease in the formation of 14CO2 and 14C-lipids from 1-14C-glycerol. When the decrease in the specific activity of the tracer is considered to calculate the respective velocities, it turns out that glycerol actually enhances the rate of synthesis of both CO2 and glyceride glycerol. Glucose enhances the rate of synthesis of CO2 and fatty acids from glycerol but decreases the rate of glyceride glycerol synthesis from the same substrate. While the Km of the glycerol effect is much lower that the physiological concentrations of glycerol the Ka and Ki of the glucose effects are above or close to its concentration in blood. The results are discussed in terms of the competitive effects of glucose and glycerol for the synthesis of alpha-glycerophosphate and the necessity of glucose for lipogenesis from glycerol in adipose tissue.

The effect of glucose, insulin and adrenaline on glycerol metabolism in vitro in rat adipose tissue

The uptake and utilization of [1-14C]glycerol was determined in pieces of rat epididymal fat-pads incubated in Krebs--Ringer bicarbonate buffer containing albumin. Insulin (200 muunits/ml), adrenaline (epinephrine; 0.5 mug/ml) and glucose (0, 5, 15 and 20 mM) were added to the medium. Changes in the specific radioactivity of the tracer during the incubation were taken into account in calculating the rate of glycerol utilization. Adrenaline decreased glycerol uptake, whereas insulin plus adrenaline increased it. The rate of incorporation of glycerol into glycerides was decreased by adrenaline and insulin, singly or together. Insulin increased the rate of formation of CO2 and fatty acids from glycerol. The formation of CO2 and fatty acids was further enhanced by insulin plus adrenaline. The decrease in glycerol uptake induced by adrenaline, the decrease in incorporation of glycerol into glycerides induced by insulin and insulin plus adrenaline and the synthesis of fatty acids were dependent on the presence of glucose in the medium. Thus insulin and adrenaline act on glycerol utilization in adipose tissue and some of their effects are mediated by action on glucose metabolism, but others are independent of this.