Diferenças clínicas, epidemiológicas e biológicas entre o câncer na criança e no adulto

O câncer representa hoje a primeira causa de morte por doença entre a população de faixa etária compreendida entre 1 e 21 anos nos Estados Unidos e em outros países economicamente desenvolvidos. No Brasil, esta doença figura como a terceira causa de morte por doença entre a população de faixa etária compreendida entre 1 e 14 anos, sendo já a primeira causa de óbito no município e no estado de São Paulo no grupo etário compreendido entre 5 e 14 anos, excluindo-se acidentes e causas externas. O objetivo deste artigo é informar a classe médica, principalmente a pediátrica, das particularidades do câncer infantil e de suas diferenças com as formas dos adultos, mais conhecidas e frequentes. Graças à moderna abordagem multidisciplinar, o câncer infantil pode atingir índices de cura de 60% a 70%, mas, para tal, é imprescindível o diagnóstico precoce. Portanto, é importante que toda a comunidade pediátrica mostre-se motivada e informada sobre os sinais e sintomas das neoplasias pediátricas, já que não dispomos de métodos de “screening” tão úteis e eficazes como para o controle do câncer do adulto.

Association of EGFR c.2073A>T Polymorphism with Decreased Risk of Diffusely Infiltrating Astrocytoma in a Brazilian Case-Control Study

Epidermal growth factor receptor (EGFR) gene overexpression has been implicated in the development of many types of tumors, including glioblastomas, the most frequent diffusely infiltrating astrocytomas. However, little is known about the influence of the polymorphisms of EGFR on EGFR production and/or activity, possibly modulating the susceptibility to astrocytomas. This study aimed to examine the association of two EGFR promoter polymorphisms (c-191C>A and c.-216G>T) and the c.2073A>T polymorphism located in exon 16 with susceptibility to astrocytomas, EGFR gene expression and survival in a case-control study of 193 astrocytoma patients and 200 cancer-free controls. We found that the variant TT genotype of the EGFR c.2073A>T polymorphism was associated with a significantly decreased risk of astrocytoma when compared with the AA genotype [sex- and age-adjusted odds ratio 0.51, 95% confidence interval 0.26–0.98]. No association of the two promoter EGFR polymorphisms (or combinations of these polymorphisms) and risk of astrocytomas, EGFR expression or survival was found. Our findings suggest that modulation of the EGFR c.2073A>T polymorphism could play a role in future therapeutic approaches to astrocytoma.

Abstract A10: Epigenetic mechanisms in liver tumors: Gene expression analysis of epigenetic machinery in hepatoblastomas

Liver tumors in children are rare and account for only 1-4% of all pediatric solid tumors. While hepatocellular carcinoma is predominant in adults, the most common liver cancer in children is hepatoblastoma, an embryonal tumor. The prognosis of patients with advanced tumor stages remains poor as well as surviving children often face severe effects following aggressive chemotherapy.

Hepatoblastomas carry a low mutational burden, and the impairment of epigenetic mechanisms, which are the core of embryogenesis and development, stands out as an alternative route for tumorigenesis.

The main objective of this study was to explore the role of genes associated with methylation and hydroxymethylation in hepatoblastomas. The expression of seven genes of the epigenetic machinery (DNMT1, DNMT3A, DNMT3L, UHRF1, TET1, TET2, and TET3) was analyzed by qPCR (Taqman). The cohort of tumors consisted of 21 hepatoblastomas and a control group of 8 non-tumor differentiated liver tissues. Additionally, a 5hmC quantification assay (Quest 5-hmC DNA ELISA Kit) was applied to assess the level of 5hmC in tumors.

TET1 and TET2 genes, whose proteins are responsible for the active demethylation of 5-methylcytosine (5mC), and consequent production of 5-hydroxymethylcytosine (5hmC), were found to be upregulated. A significant increase in the 5hmC levels was also evident in tumor samples when compared to nontumoral tissues.

We have shown in hepatoblastomas an upregulated profile of TET1 and TET2 enzymes with a resulting elevation of 5hmC level in tumors. Our data suggest that hepatoblastomas could present a pluripotency pattern of gene expression when compared to differentiated livers; to address this issue, the expression levels of three genes associated with pluripotency (POU5F1, SOX2 and NANOG) were evaluated, with no significant alteration.

Therefore, although hepatoblastomas have a more undifferentiated molecular profile than mature hepatocytes, our results indicate that tumor cells are already commited with the differentiation process. Altogether, these data suggest that the development of hepatoblastomas is associated with a blockage in the stages of hepatoblasts.

Citation Format: Maria Rivas, Cecília da Costa, Silvia Toledo, Monica Cypriano, Luiz Caires, Ernesto Goulart, Dirce Carraro, Isabela Werneck, Carla Rosenberg, Mayana Zatz, Ana Krepischi. Epigenetic mechanisms in liver tumors: Gene expression analysis of epigenetic machinery in hepatoblastomas [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A10.

Use of interferon alpha in intratumoral chemotherapy for cystic craniopharyngioma

OBJECTIVES

This study analyzed the intratumoral activity of interferon alpha (IFN-alpha) in the treatment of cystic craniopharyngiomas.

PATIENTS AND METHODS

From January 2000 to January 2004, nine patients presenting with cystic craniopharyngiomas were treated with intratumoral injection of IFN-alpha at the Pediatric Oncology Institute of the Federal University of São Paulo-Escola Paulista de Medicina. Age ranged from 1 year and 10 months to 18 years (mean 10 years). All intratumoral catheters were inserted by a subfrontal approach. Doses varied from 36 to 108 MU.

RESULTS

There was complete disappearance of the lesion in seven cases. In two cases, partial reduction of tumor size was observed at follow-up. Follow-up varied from 1 year to 3 years and 6 months (mean 1 year 8 months).

CONCLUSIONS

IFN-alpha proved to be an effective drug in the control of cystic craniopharyngiomas. Additional studies should be carried out to determine the optimal dose of IFN-alpha in the treatment of cystic craniopharyngioma. In addition, other drugs possessing high efficacy and low neurotoxicity should be analyzed.

Impact of mouthrinses on morning bad breath in healthy subjects

BACKGROUND

During sleep, a proliferation of oral bacteria is responsible for the release of offending gases in morning breath even in healthy people. Thus, the aim of this study was to evaluate the bad breath-inhibiting effect of four commercially available mouthrinses (0.03% triclosan, 0.12% chlorhexidine gluconate, 0.05% cetylpyridinium chloride and essential oils) on morning breath when compared with a positive and a negative control.

METHOD

A six-step double-blind, crossover, randomised study was conducted in 12 dental students with healthy periodontium, who refrained from mechanical plaque control during a 4-day period. The subjects were instructed to rinse twice daily with the assigned product during each period. Fifteen-day washout intervals were used. Before professional plaque and tongue coating removal (baseline), the morning breath was scored through volatile sulphur compounds (VSCs) level measured by a sulphide monitor. After 4 days, VSCs and plaque index (PI) were recorded.

RESULTS

Even in the absence of mechanical plaque control, there was a decrease in VSC level with the use of all mouthrinses, with the exception of an increase with the use of the negative control. The VSC formation was inhibited in descending order, by positive control (0.2% chlorhexidine), 0.12% chlorhexidine, triclosan and essential oils and cetylpyridinium chloride. Plaque formation was inhibited by chlorhexidine mouthrinses and essential oils.

CONCLUSIONS

These findings suggest that mouthrinses can reduce morning bad breath, and that such a reduction is not attributable only to the reduction of supragingival plaque formation.

Modulation of autoreactive responses of peripheral blood lymphocytes of patients with systemic lupus erythematosus by peptides based on human and murine anti-DNA autoantibodies

Two peptides, based on the sequences of the complementarity-determining regions (CDR) 1 and 3 of a pathogenic murine monoclonal anti-DNA autoatibody that bears the 16/6 idiotype (Id), were shown to either prevent or treat an already established systemic lupus erythematosus (SLE) in two murine models of lupus. Two additional peptides based on the human monoclonal anti-DNA, 16/6 Id were synthesized. This study was undertaken in order to investigate the ability of the CDR-based peptides to immunomodulate SLE-associated responses of peripheral blood lymphocytes (PBL) of SLE patients. PBL of 24 of the 62 SLE patients tested proliferated in vitro following stimulation with the human 16/6 Id. Peptides based on the CDRs of both the human and murine anti-DNA autoantibodies inhibited efficiently and specifically the 16/6 Id-induced proliferation and IL-2 production. The latter inhibitions correlated with an up-regulated production (by 2.5-3.5-fold) of the immunosuppressive cytokine, TGF-beta. Overall, the results of our study demonstrate that the CDR-based peptides are capable of down-regulating in vitro autoreactive T cell responses of PBL of SLE patients. Thus, these peptides are potential candidates for a novel specific treatment of SLE patients.

Effect of triclosan dentifrices on mouth volatile sulphur compounds and dental plaque trypsin-like activity during experimental gingivitis development

BACKGROUND

The objective of this study was to evaluate the effect of three commercial anti-plaque dentifrices containing 0.3% triclosan + 2% pvm/ma (Colgate Total), 0.3% triclosan + 0.75% Zn (Signal Global) and 0.3% triclosan + 5% PPi (Crest Complete) in comparison with an experimental dentifrice (0.3% triclosan + 2% pvm/ma + 0.75% Zn + 4% PPi) and a control dentifrice without anti-plaque agents on trypsin-like activity in dental plaque (detected by the hydrolysis of [Na-Benzoyl-DL-Anginine p-Nitroanilide (BAPNA)] and volatile sulphur compounds (VSCs) in mouth air during experimental gingivitis development.

METHOD

A 5-step double blind, crossover experimental gingivitis study was conducted on 19 volunteers during a 21-day period. The volunteers refrained from brushing an experimental quadrant of teeth. The dentifrices were applied to those teeth via toothshield three times per day; simultaneously they brushed the other teeth with the same dentifrice. After each period, VSCs in mouth air and BAPNA hydrolysis by dental plaque accumulated in the experimental quadrant were determined.

RESULTS

There was an increase (p < 0.05) in VSCs in mouth air when experimental gingivitis was induced in only one quadrant of teeth. None of the dentifrices was able to avoid the increase of VSCs during the experimental gingivitis development. The majority of the antiplaque dentifrices evaluated reduced the increase of VSC formation in comparison with the control (p < 0.05). There was no relationship between the ability of the dentifrices in reducing VSC formation and the inhibition of trypsin-like activity in dental plaque.

CONCLUSIONS

Anti-plaque dentifrices reduce the increase of VSCs that occurs during the development of experimental gingivitis.

Comparative genomic hybridization analysis identifies gains of 1p35 approximately p36 and chromosome 19 in osteosarcoma

Osteosarcomas (OS) are aggressive tumors of the bone and often have a poor prognosis. Conventional cytogenetic analyses of OS have revealed highly complex karyotypes, with numerous abnormalities. In this study, we analyzed 18 untreated OS tumors from 17 patients of the younger incidence age group by comparative genomic hybridization (CGH), 4 tumors by spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH). Comparative genomic hybridization identified frequent copy number changes of the chromosomal region 1p (10/17) and gain of part or all of chromosome 19(8/17). In addition gains were observed at 5p(3/17), 8q(3/17), 16p(3/17), and 17p(5/17); and losses at chromosomes 2q(3/17), 10(4/17) and 13(3/17). High level gains were detected in the 8q23 approximately q24 region in two tumors as well as at 17p in one primary and a metastatic tumor. Minimal regions of gain were present at 1p35 approximately p36.3 (8/17); 5p14 approximately p15.2 (3/17), and 8q22 approximately q24.3 (3/17). SKY analysis demonstrated that OS has a complex pattern of clonal and non-clonal rearrangements and helped confirm the structural basis for the imbalances detected by CGH. Spectral karyotyping confirmed an overall pattern of chromosomal gain affecting 1p in all four tumors. Fluorescence in situ hybridization analysis from these tumors confirmed the gain of the 1p36 region in 2 tumors as determined by CGH analysis as well as the amplification of 8q.

Soft tissue injuries to face and neck: early assessment and repair

The principles of assessment and repair of soft tissue trauma of the face are outlined. The importance of an adequate preoperative evaluation is emphasized. Recognizing lesions in the deep vital structures is extremely important in the initial approach to these patients. The postoperative care and the best management of the sequelae are described.

Histometric evaluation of bone regeneration around immediate implants partially in contact with bone: a pilot study in dogs

Bone regeneration was evaluated around immediate implants partially in contact with bone, with or without the concurrent application of a combination of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-1). Mandibular premolars were removed, and the implant osteotomies were prepared; a uniform circumferential gap was prepared 1.25 mm beyond the width of the implant bed in the coronal half. Twelve implants (8.5 x 3.75 mm) were inserted in six dogs. Before insertion, an implant received a single application of 5 micrograms/mL of PDGF and IGF-1 delivered in 0.10 mL of 4% methylcellulose gel or 0.10 mL of 4% methylcellulose gel only as a control. To label regenerated bone, a 2% calcein green solution was administered by intramuscular injection at 0, 7, 15, 30, and 45 days after implant insertion Three and 8 weeks after implant insertion undecalcified sections were obtained, and the degree of bone to implant contact, the bone area, and the intensity of bone labeling were measured into the limits of the eight most coronal threads of the implant (four threads on each side of each implant). The results showed a greater extension of bone-to-implant contact, a larger percentage of bone area, and greater intensity of bone labeling for test versus control implants (P < .01). Within the limits of the present study, it was concluded that the combination of PDGF/IGF-1 might be an alternative for enhancing bone healing around implants partially in contact with bone.

Platelet-derived growth factor/insulin-like growth factor-1 combination and bone regeneration around implants placed into extraction sockets: a histometric study in dogs

This study evaluated, by histometric analysis, the wound healing process of bone around implants placed into extraction sockets with or without the concurrent application of a combination of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-1). Mandibular premolars were removed, and 32 implants were inserted in eight dogs. Before insertion, two implants received a single application of 5 micrograms/mL of PDGF and IGF-1 delivered in 0.10 mL of 4% methylcellulose gel or 0.10 mL of 4% methylcellulose gel only as a control. To label regenerated bone, a 2% calcein green solution was administered by intramuscular injection at 0, 7, 15, 30, 45, 60, and 75 days after implant insertion. Three, 8, and 12 weeks after implant insertion, undecalcified sections were obtained, and the degree of bone contact with the implant surface, the bone area, and the intensity of bone labeling were measured into the limits of the threads of the implant. Greater extension of bone/implant contact (paired t test, P < .05) was observed in test (22.4% +/- 13.7%) than in control (17.2% +/- 13.6%) implants at 3 weeks. One-way ANOVA revealed a higher intensity of bone labeling (P < .05) at 3 weeks than at 12 weeks (127.8 +/- 42.59 and 56.7 +/- 26.34, gray scale values) for test implants. Within the limits of the present study, it was concluded that the combination of PDGF/IGF-I actively took part in the initial phase of bone repair.

Effect of 3 dentifrices containing triclosan and various additives. An experimental gingivitis study

BACKGROUND

The antiplaque and antigingivitis effect of 3 dentifrices was evaluated using the 21-day partial-mouth experimental model of gingivitis.

METHOD

25 volunteers took part in this cross-over, double-blind study, carried out in 4 phases of 21 days each. For each phase of the study, a toothshield of the IV quadrant was constructed for each volunteer. 2 antiplaque dentifrices from the market, one containing triclosan + pvm/ma and the other triclosan + Zn, were compared with an experimental formulation and its placebo. The experimental dentifrice contained triclosan + pvm/ma + Zn + PPi and the placebo (control) did not contain these substances. The subjects were stratified according to their whole-mouth baseline plaque (PI), gingivitis (GI) and bleeding (BI) index scores, and then randomly assigned to 1 of 4 dentifrices. During each phase, while the volunteers brushed their teeth with one of the dentifrices, the IV quadrant was protected by the toothshield filled with the dentifrice used. After each phase, dental plaque, gingivitis and bleeding indices were determined.

RESULTS

The results showed that only the formulation containing triclosan + pvm/ma + Zn + PPi was able to reduce PI (28.8%), GI (35.9%) and BI (30.4%) in comparison with controls (p<0.05).

CONCLUSIONS

The data suggest that a dentifrice containing the combination of triclosan + pvm/ma + Zn + PPi should be formulated for dental plaque control.

Effect of calcitonin on bone healing following titanium implant insertion

The purpose of this study was to evaluate the effects of calcitonin administration on bone healing, following titanium implant insertion. Thirty adult New Zealand rabbits received one implant in each femur. Fifteen animals were randomized to provide test (calcitonin) and control (saline solution) groups. The animals were sacrificed 7, 14, 21, 28 and 42 days after the surgical procedure. The analyzed parameters were new endosteal/periosteal bone length, new endosteal/periosteal bone area and total cortical length. Considering treatment, histometric measurements showed significant differences (p < 0.05) favoring the control group considering periosteal bone length and periosteal bone area, the other parameters were statistically similar between control and test groups.

Prospective study of Campylobacter jejuni infection in Chilean infants evaluated by culture and serology

A prospective study of Campylobacter jejuni infection was performed during a 6-month period in a cohort of 198 Chilean infants. Surveillance was based on biweekly home visits by a team of trained nurses. C. jejuni colonization was studied by culturing stool samples from diarrheal episodes and paired asymptomatic controls and by performing an enzyme-linked immunosorbent assay developed to measure C. jejuni outer membrane protein polyvalent antibodies in a representative group of infants. C. jejuni was isolated from 30 of 299 diarrheal episodes (10%) and from 17 of 304 samples from asymptomatic infants (6%). Significantly higher (P less than 0.05) C. jejuni illness/infection ratios were found in infants less than 9 months old. Polyvalent antibodies to C. jejuni were found in 27 of 89 serum samples (30%). The lowest prevalence (4%) was observed among infants less than 9 months old, and the highest was found in patients older than 15 months (63%; P less than 0.01). Data obtained by analysis of paired serum samples revealed a significant increase in the number of seropositive individuals, from 8% on admission to 50% at the end of the protocol (P less than 0.001). The change in the immune status of these infants was associated with symptomatic infection in 9 of 18 cases. The antibody rise found in the remaining nine infants suggested the presence of asymptomatic C. jejuni infections. This inference was documented by the isolation of C. jejuni from stools of two of these infants when the infants were randomly studied while asymptomatic. This study points out the impact of C. jejuni-associated diarrheal episodes and the high frequency with which asymptomatic infections elicit specific antibodies in infants living in areas such as Chile.

High glucose prolongs cell-cycle traversal of cultured human endothelial cells

There is evidence suggesting that the diabetic state adversely affects replication of certain cell populations. We document that exposure to high ambient glucose (20 mM) induces delay in various phases of the cell cycle of human endothelial cells in primary culture. Cells in S phase were labeled with bromodeoxyuridine (an analogue of thymidine), and the cell-cycle position of the labeled cohort was analyzed by flow cytometry at successive time points. The movement of cells exposed to high glucose for 7-8 days was retarded both in S and G2 phases so that the increase in bromodeoxyuridine-positive cells over 24 h was 1.6-fold, versus 2.0-fold in control cultures. In experiments in which mitotic arrest with vinblastine was used to investigate the movement of cells out of G1 phase without interference from reentering cells, depletion of the G1 compartment was significantly inhibited in cultures grown in high glucose. The effects of chronic high glucose on cell cycle occurred while total protein synthesis was not diminished. Acute exposure to high glucose had no effect on cell-cycle traversal or cell generation time. Cell-cycle abnormalities observed in this study may relate to the DNA damage we have previously observed in endothelial cells exposed to high glucose and, if occurring in vivo, could be of pathogenetic importance for the vascular lesions and teratogenicity of diabetes.

The polyol pathway and glucose 6-phosphate in human endothelial cells cultured in high glucose concentrations

In an attempt to identify the mechanisms underlying the ill effects of high glucose previously described in cultured human endothelial cells, we have investigated in these cells the activity of the polyol pathway and accumulation of glucose 6-phosphate, a powerful agent of non-enzymatic glycosylation. Sorbitol accumulation varied among different batches of cells (primary cultures). In presence of 5 mmol/l glucose the cellular sorbitol content ranged from 0.04 to 0.12 nmol/10(6) cells. When cells were exposed to 20 mmol/l glucose the sorbitol content increased by 2- to 3-fold to concentrations of 0.08-0.38 nmol/10(6) cells (p less than 0.01). Addition to the culture medium of 100 mumol/l Sorbinil, an inhibitor of aldose reductase, resulted in a substantial inhibition of sorbitol accumulation throughout the 14 days in culture, but the degree of inhibition varied inversely with the duration of cell exposure to high glucose (70% inhibition in cells exposed to high glucose and Sorbinil for 1-3 days versus 14% inhibition in cells exposed for 14 days, p less than 0.01). Sorbinil treatment failed to improve even slightly the abnormalities in cellular replication induced by high glucose. The cellular content of glucose 6-phosphate was augmented 3-fold by exposure to 20 mmol/l glucose (p less than 0.001). In conjunction with other studies these results indicate that in this model the polyol pathway is not an osmotically or metabolically important mechanism of glucotoxicity, and that the inhibitory activity of Sorbinil on the polyol pathway of human tissues may be a function of their length of exposure to hyperglycaemia. The consequences of intracellular accumulation of glucose 6-phosphate await investigations.

Increased single strand breaks in DNA of lymphocytes from diabetic subjects

Certain aspects of the chronic complications of diabetes suggest that, with time, the abnormal metabolic milieu leads to irreversible changes in some cell populations. Since we have previously observed that high glucose concentrations induce an increase in single strand breaks in the DNA of cultured human endothelial cells, we have investigated whether the same abnormality occurs in cells derived from the in vivo diabetic environment. Peripheral blood lymphocytes obtained from 21 type I diabetic patients and age- and sex-matched controls were tested for rate of unwinding in alkali (a measure of DNA single strand breaks). The patients were subdivided into two groups on the basis of glycohemoglobin values above or below 9%. The group with glycohemoglobin values of 12.9 +/- 2.4% (mean +/- SD), but not the group with glycohemoglobin values of 7.4 +/- 1.5%, showed accelerated unwinding of lymphocyte DNA when compared to controls (P less than 0.01). These studies suggest that poorly controlled diabetes may result in DNA lesions, whose impact on long-term complications deserves to be investigated.

Myo-inositol enhances the proliferation of human endothelial cells in culture but fails to prevent the delay induced by high glucose

Evidence is accumulating, indicating that the abnormal metabolic milieu of diabetes might interfere with orderly replication of some cellular systems and in vitro studies point to a causal contribution of elevated glucose. We had previously shown that human umbilical vein endothelial cells cultured in 20 mmol/L glucose are delayed in achieving saturation density primarily as a consequence of decreased cellular proliferation. We have now addressed whether depletion of myo-inositol--a prevailing consequence of hyperglycemia in other tissues and overcome by provision of supplemental inositol--might play a role in the observed replicative abnormality. Control cultures (5 mmol/L glucose) displayed a dose-dependent response to myo-inositol supplementation that was maximal at concentrations (40 mumol/L) matching physiologic serum levels. The increment in cell number was (mean +/- SD) 141 +/- 20% of control (P less than 0.001), and saturation density was achieved at a cell number 160% higher than in nonsupplemented cultures. Thymidine incorporation and cell cycle studies documented that myo-inositol increased the number of cells cycle studies documented that myo-inositol increased the number of cells engaged in DNA synthesis. These effects of myo-inositol, as well as the dose-response relationship between ambient inositol levels and increments in cell number, were not significantly modified by 20 mmol/L glucose with the exceptions of a transient lesser effect of the physiologic doses during rapid proliferation (day 6) and a larger effect of all doses of myo-inositol in later stages of growth curve (day 12).(ABSTRACT TRUNCATED AT 250 WORDS)

High glucose induces DNA damage in cultured human endothelial cells

Morphologic and functional abnormalities of vascular endothelium are well recognized in diabetes. In view of our previous finding that high glucose concentrations accelerate death and hamper replication of cultured human endothelial cells, we have investigated in the same model the possibility that exposure to high glucose may result in DNA damage. DNA from human endothelial cells--but not from fibroblasts--exposed to 30 mM glucose for 9-14 d manifested an accelerated rate of unwinding in alkali indicative of an increased number of single strand breaks (P less than 0.001 vs. control). Endothelial cells exposed to high glucose also manifested an increased amount of hydroxy-urea-resistant thymidine incorporation (333 +/- 153 cpm/10(5) cells vs. 88 +/- 42 in control cells, mean +/- SD, P = 0.04), which is indicative of increased DNA repair synthesis. Neither DNA damage nor repair synthesis were increased by medium hypertonicity achieved with 30 mM mannitol. These findings suggest the possibility that, under conditions of high ambient glucose, excess glucose entry in cells that are insulin independent for glucose transport may, directly or indirectly, perturb DNA function. Further, they suggest the possibility that different individual capabilities to repair DNA damage--a process that is under genetic control--may represent a mechanism for different individual susceptibilities to development of diabetic vascular complication.

Glucose toxicity for human endothelial cells in culture. Delayed replication, disturbed cell cycle, and accelerated death

Functional and anatomical abnormalities of endothelium may represent a pathway to the increased vascular permeability and accelerated atherosclerosis characteristic of diabetes. To identify whether and how hyperglycemia may compromise the endothelial barrier, we have employed an in vitro system of human endothelial cells obtained from umbilical veins and cultured in elevated glucose concentrations (20 mM). Under these conditions, the achievement of saturation density was substantially delayed, with cell counts throughout most of the growth curve being 70-80% of control (P less than 0.002). More profound suppression of cell number was present in cultures exposed to 40 mM glucose. Similar, albeit slightly lesser, effects were observed in cultures exposed to 20 mM mannitol, mimicking the hypertonicity of the high glucose media. The effect of elevated glucose and mannitol was primarily mediated by a decrease in overall rate of replication of the endothelium as documented by the lower mitotic index (P less than 0.025). Analysis of the distribution of cells along phases of the cell cycle uncovered in the high glucose cultures a decreased proportion of cells in G0-G1 (70.5 +/- 5% versus 73.2 +/- 4% in controls, P less than 0.05) and an increased proportion of cells in S phase (16.5 +/- 2.7% versus 13.5 +/- 2.2% in controls, P less than 0.01), suggesting that the replicative delay is likely to occur between the phase of DNA synthesis and mitosis. Increased cellular death was specifically observed in the cultures exposed to elevated glucose concentrations (P less than 0.05), but it could account for only a minor portion of the deficit in cell number.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial monosomy 13 and 21 due to a familial 13/21 translocation

Two patients are described with a monosomy for the proximal part of the long are of chromosome 13 and for the distal part of the long arm of chromosome 21, due to an unbalanced 13/21 translocation.

The effect of dexamethasone in traumatic changes of the periodontium of marmosets (Callithrix jacchus)

The systemic administration of steroid hormone (0.400 mg of Dexamethasone every 2 days), during a 28-day period in marmosets (Callithrix jacchus) produced modifications in the evolution of the experimental periodontal traumatism. The observed changes were osteoporosis and reduction of the periodontal fibers in quantity as well as a reduction of repair process, when compared to the control group that only received the action of the trauma from occlusion.