[A 10-year longitudinal study of the progression of destructive periodontal disease in adult and elderly]

OBJECTIVE

To study the progression of destructive periodontal disease in adult and elderly aged 20 to 80. The examinees were followed 10 years to determine whether the rates for progression of periodontal disease were different than the populations in the more developed countries.

METHODS

In 1984, at baseline, 587 subjects had been examined and by 1994, 440 of them still available for follow-up study, and 398 persons remained dentate. Tooth mobility, plaque, calculus, gingival conditions, attachment levels, and probing depths on 4 sites of each tooth present were checked and recorded by the same two examiners.

RESULTS

All subjects had > or = 2 mm attachment loss over 10-year period. Some teeth, such as mandibular incisors and maxillary molars, had higher progression rate than others. The mean attachment loss rate did not differ significantly between age groups, and were similar to those reported for populations in the more developed countries.

CONCLUSIONS

The rate for progression of periodontal disease in this study were not significantly different between the examinees and the populations in more developed countries; and also were not significantly different among the different age groups. The causes of destructive periodontal disease in humans are more likely intrinsic factors.

Multicolor fluorescent differential display

Differential display and DNA microarray have emerged as the two most popular methods for gene expression profiling. Here, we developed a multicolor fluorescent differential display (FDD) method that combines the virtues of both differential display in signal amplification and DNA microarray in signal analysis. As in DNA microarray, RNA samples being compared can be labeled with either a red or green fluorescent dye and displayed in a single lane, allowing convenient scoring and quantification of the differentially expressed messages. In addition, the multicolor FDD has a built-in signal proofreading capability that is achieved by labeling each RNA sample from a comparative study with both red and green fluorescent dyes followed by their reciprocal mixings in color. Thus, the multicolor FDD provides a platform upon which a sensitive and accurate gene expression profiling by differential display can be automated and digitally analyzed. It is envisioned that cDNAs generated by the multicolor FDD may also be used directly as probes for DNA microarray, allowing an integration of the two most widely used technologies for comprehensive analysis of gene expression.

HPV16 E6 gene variations in invasive cervical squamous cell carcinoma and cancer in situ from Russian patients

HPV16 is frequently seen in invasive cervical cancer (ICC) and cervical intraepithelial neoplasia (CIN). Its E6 gene has frequent sequence variations. Although some E6 variants have been reported to have different biochemical or biological properties, they do not show geographical identity. Moreover, the definition of 'variant' has been a source of confusion because it has been based on all departures from the 'prototype' once isolated randomly from an ICC case. We amplified the HPV16 E6 gene by PCR from fresh-frozen tissue of 104 cases of ICC and CIN from Russian patients and sequenced it in positive cases. We found that 32 of 55 (58.2%) ICC cases and 18 of 49 (36.7%) CIN cases were HPV 16-positive and we could identify 3 groups of E6 variants: group A was characterized by G at nt 350 where group B had T, and group M was a heterogeneous mixture of unique E6 variants; no significant difference existed in the distribution of the different groups between ICC and CIN; the clinically malignant (as defined by FIGO stage) order between the groups was M > A > B in ICC; in the cases with a single HPV16 E6 sequence, coexisting ICC, CIN and normal epithelium in the same patient shared the E6 variant; and 4 cases of ICC had double/multiple E6 variants. The results did not show any importance of E6 variants for ICC progression in Russian women. The results also indicated that the original HPV16 variant persisted during ICC progression, and that at a low frequency, double infections and/or mutation of variants might occur.

Modulation of nucleotide excision repair capacity by XPD polymorphisms in lung cancer patients

Sequence variations have been identified in a number of DNA repair genes, including XPD, but the effect of these polymorphisms on DNA repair capacity (DRC) is uncertain. We therefore examined XPD polymorphisms at Lys751Gln and Asp312Asn in 341 white lung cancer cases and 360 age-, sex-, ethnicity-, and smoking-matched controls accrued in a hospital-based molecular epidemiological study of susceptibility markers for lung cancer. As previously reported, DRC was statistically significantly lower in the cases than in the controls (7.8% versus 9.5%; P < 0.001), which represents an average 18% reduction among the cases. The variant Lys751Gln and Asp312Asn allele frequencies were 0.36 and 0.29, respectively, for the cases and 0.33 and 0.27, respectively, for the controls. For subjects homozygous for the variant genotype at either locus, the adjusted odds ratio [95% confidence interval (CI)] was 1.84 (1.11-3.04; P = 0.018, for trend). Both cases and controls with the wild-type genotypes exhibited the most proficient DRC. The risk (95% CI) for suboptimal DRC (defined as less than the median DRC value among the controls) was 1.57 (0.74-3.35) for those with the Gln/Gln751 genotype. For cases with the Asn/Asn312 genotype, the risk (95% CI) was 3.50 (1.06-11.59). For cases who were homozygous at either locus, the risk was 2.29 (1.03-5.12; P = 0.048, for trend). The pattern was less evident among the controls, although there was a nonsignificant 41% increase in the risk of suboptimal DRC for controls who were homozygous at either locus. These results suggest that the two XPD polymorphisms have a modulating effect on DRC, especially in the cases.

Apolipoprotein E genotypes and the incidence of Alzheimer's disease among persons aged 75 years and older: variation by use of antihypertensive medication?

The authors examined the impact of the apolipoprotein E (APOE)(*)epsilon4 allele on Alzheimer's disease incidence in relation to use of antihypertensive medication. A population-based (Kungsholmen Project) cohort of 985 nondemented Swedish subjects aged >/=75 years was followed for an average of 3 years (1990-1992); 164 dementia (122 Alzheimer's disease) cases were identified. Compared with (*)epsilon3/(*)epsilon3, the APOE(*)epsilon4 allele increased the risk of developing dementia (relative risk (RR) = 1.5, 95% confidence interval (CI): 1.1, 2.1) and Alzheimer's disease (RR = 1.7, 95% CI: 1.2, 2.5). Subjects using antihypertensive medication at baseline (n = 432, 80% used diuretics) had a decreased risk of dementia (RR = 0.6, 95% CI: 0.5, 0.9) and Alzheimer's disease (RR = 0.5, 95% CI: 0.3, 0.8) after adjustment for several variables, including APOE. The effect of antihypertensive medication use was more pronounced among (*)epsilon4 carriers. For those not using antihypertensive medication, the relative risks of dementia and Alzheimer's disease for carriers were 2.2 (95% CI: 1.4, 3.4) and 2.3 (95% CI: 1.4, 3.7), respectively. The corresponding relative risks for those using antihypertensive medication were 0.9 (95% CI: 0.5, 1.6) and 1.1 (95% CI: 0.6, 2.2). The APOE(*)epsilon4 allele is an important predictor of dementia and Alzheimer's disease incidence. Further studies are needed to clarify whether use of antihypertensive medication, especially diuretics, modifies the effect of the allele.

Quantitative assessment of in vitro jets based on three-dimensional color Doppler reconstruction

Three-dimensional (3-D) color Doppler imaging of flow jets was performed to investigate the effects of flow rate and orifice size on jet volumes. Flow jets were generated using a flow model to simulate mitral regurgitation. This flow model consisted of a ventricular chamber, a valvular plate and an atrial chamber. Steady flow was driven through circular orifices having diameters of 2.5, 3.5, 4.5, and 6 mm, respectively, with flow rates of 5, 10, 15, 20, and 25 mL/s to form free jets in the atrial chamber. An ATL Ultramark 9 HDI system was used to perform 3-D color Doppler imaging of the flow jets. A transesophageal probe was rotated by a stepper motor to create 3-D color Doppler images of the jets. The color jet volumes for different hemodynamic conditions were measured and then compared with the theoretical predictions. Results showed that the jet volume estimated from the 3-D color Doppler was directly proportional to the flow rate and inversely proportional to the orifice size. The estimated jet volumes correlated well (r > 0.95) with theoretical predictions. This study supports the use of color jet volume as a parameter to quantify mitral regurgitation.

Dietary restriction stimulates BDNF production in the brain and thereby protects neurons against excitotoxic injury

Dietary restriction (DR) increases the lifespan of rodents and increases their resistance to several different age-related diseases including cancer and diabetes. Beneficial effects of DR on brain plasticity and neuronal vulnerability to injury have recently been reported, but the underlying mechanisms are unknown. We report that levels of brain-derived neurotrophic factor (BDNF) are significantly increased in the hippocampus, cerebral cortex, and striatum of rats maintained on a DR regimen compared to animals fed ad libitum (AL). Seizure-induced damage to hippocampal neurons was significantly reduced in rats maintained on DR, and this beneficial effect was attenuated by intraventricular administration of a BDNF-blocking antibody. These findings provide the first evidence that diet can effect expression of a neurotrophic factor, demonstrate that BDNF signaling plays a central role in the neuroprotective effect of DR, and proffer DR as an approach for reducing neuronal damage in neurodegenerative disorders.

Analysis of intratumoral heterogeneity of chromosome 3p deletions and genetic evidence of polyclonal origin of cervical squamous carcinoma

Investigation on intratumoral genetic heterogeneity provides an important insight into the roles of genetic alterations in human carcinogenesis and clues to clonal origin of tumors. Intratumoral heterogeneity of genetic changes of cervical cancer has not been described so far. In this study, we analyzed the intratumoral heterogeneity of chromosome 3p deletions and X-chromosome inactivation patterns in multiple microdissected samples from each individual cervical cancer, attempting to understand the roles of 3p deletions in development of cervical cancer and its clonal origin. Totally, 120 normal and lesional samples from 14 cases of fresh cervicalcancers were analyzed. Frequency and patterns of allelic losses of 3p were assessed by polymerase chain reaction (PCR) amplification of 12 microsatellite markers flanking the frequently deleted regions of 3p, followed by Genescan analysis in an ABI 377 DNA sequencer. Loss of heterozygosity was recorded as heterogeneous pattern (LOH present in parts of samples or LOH involving different alleles among different samples) and homogeneous pattern (LOH involving identical alleles in all samples from the tumor). Allelic loss affecting at least one marker was detected in 8 of 14 cases (57%). Allelic losses, both homogeneous and heterogeneous, were frequently detected at FHIT gene region (D3S1300, 40% and 60%; D3S4103, 27.3% and 54.6%), 3p21.3-21.2 (D3S1478, 27.3% and 45.5%), and 3p24.2-22 (D3S1283, 30% and 50%). Seven of eight LOH-positive tumors exhibited homogeneous allelic loss involving at least one of these three 3p loci. Allelic losses were present in the CIN lesions synchronous with invasive lesions positive for LOH. Our findings suggest essential roles of genes on these 3p loci, particularly the FHIT gene in participating in clonal selection and early development of cervical cancer. Most interestingly, with the combination of LOH analysis and X-chromosome inactivation analysis, we provided the first clear genetic evidence of polyclonal origin of cervical invasive cancer in two of eight cases. This finding strongly suggests the importance of field defect (possible human papilloma virus) in cervical carcinogenesis.

Retinoblastoma gene promoter directs transgene expression exclusively to the nervous system

In human, germ line mutations in the tumor suppressor retinoblastoma (Rb) predispose individuals to retinoblastoma, whereas somatic inactivation of Rb contributes to the progression of a large spectrum of cancers. In mice, Rb is highly expressed in restricted cell lineages including the neurogenic, myogenic, and hematopoietic systems, and disruption of the gene leads to specific embryonic defects in these tissues. The symmetry between Rb expression and the defects in mutant mice suggest that transcriptional control of Rb during embryogenesis is pivotal for normal development. We have initiated studies to dissect the mechanisms of transcriptional regulation of Rb during development by promoter lacZ transgenic analysis. DNA sequences up to 6 kilobase pairs upstream of the mouse Rb promoter, isolated from two different genomic libraries, directed transgene expression exclusively to the developing nervous system, excluding skeletal muscles and liver. Expression of the transgene in the central and peripheral nervous systems, including the retina, recapitulated the expression of endogenous Rb during embryogenesis. A promoter region spanning approximately 250 base pairs upstream of the transcriptional starting site was sufficient to confer expression in the central and peripheral nervous systems. To determine whether this expression pattern was conserved, we isolated the human Rb 5' genomic region and generated transgenic mice expressing lacZ under control of a 1.6-kilobase pair human Rb promoter. The human Rb promoter lacZ mice also expressed the transgene primarily in the nervous system in several independent lines. Thus, transgene expression directed by both the human and mouse Rb promoters is restricted to a subset of tissues in which Rb is normally expressed during embryogenesis. Our findings demonstrate that regulatory elements directing Rb expression to the nervous system are delineated within a well defined core promoter and are regionally separated from elements, yet to be identified, that are required for expression of Rb in the developing hematopoietic and skeletal muscle systems.

Yersinia enterocolitica O9 as a possible barrier against Y. pestis in natural plague foci in Ningxia, China

A survey of Yersinia spp, as related to plague control, was made in Haiyuan of Ganning loess plateau plague focus, Yanchi of Inner Mongolia plateau plague focus, and Yinchuan city, as a control area, in Ningxia, China. In Haiyuan, where the main plague reservoir was Mongolian ground squirrel (Citellus alaschanicus) living in the prairie, Y. enterocolitica O9 was frequently isolated from pigs, dogs, rodents living in and around houses, but only rarely from hare and Mongolian ground squirrel. In Yanchi, where the main plague reservoir was Mongolian gerbil (Meriones unguiculatus) living in the prairie and Y. pestis, which was isolated from rodents up to 1991, Y. enterocolitica O9 was sometimes isolated from pigs and rodents. In all areas, some strains of Y. enterocolitica O3 and Y. pseudotuberculosis serotypes 3 and 4b were also isolated from pigs, dogs, and from rodents. We propose that an epidemiological link exists between the prevalence of Y. pestis and Y. enterocolitica O9 in domestic and rodents living in these areas in China. The residential area in Haiyuan may be protected against Y. pestis by the domestic animals and rodents which acquired cross-protection against Y. pestis by infection with Y. enterocolitica O9, but this is not the case in the Yanchi district.

[Immunoelectron microscopic analysis of P-glycoprotein, p53, and Bcl-2 proteins expressions in lung cancer]

OBJECTIVE

To determine the ultrastructural localization of P-gp, p53 protein, and Bcl-2 protein in lung cancer cells, their relation to multidrug resistance and possible mechanisms of action.

METHODS

Expression of P-gp, p53, and Bcl-2 proteins was examined in 8 NSCLC surgical specimens and 7 SCLC bronchoscopically biopsied specimens using postembedding PAG immunolabelling technique for electron microscopy.

RESULTS

P-gp was detected on the cell membrane and the periphery of endoplasmic reticulum (ER). P53 protein was observed not only in the nuclei associated with heterochromatin but also in the cytosol. Bcl-2 protein immunoreactivity was associated with mitochondria and ER. P-gp, p53, and Bcl-2 were detected in 5(33%), 9(60%), and 4 (26.7%) out of the 15 samples examined, respectively. In 8 normal lung tissues, these three proteins were detected. Of 5 P-gp positive samples 4 were NSCLC, only 1 was SCLC after chemotherapy.

CONCLUSION

P-gp, p53, and Bcl-2 proteins are detectable immuno-electron microscopically in lung cancer cells. No correlation in expression existed between of p53 and P-gp, nor did that between p53 and Bcl-2. The plasma membrane localization of P-gp supports its action as a transmembrane drug efflux pump. P-gp may play a role in MDR in lung cancer.

A comparative study of the effects of magnetic stimulation and electric stimulation on peripheral nerve injury in rat

The influence of pulsed magnetic stimulation (MS) on the sciatic nerve injury was investigated. Thirty rats were divided into three groups equally: MS group (A), electric stimulation (ES) group (B) and the control group (C). The MS and ES were applied immediately after the first 10 min of the sciatic nerve crush. Sciatic function index (SFI), toe spreading reflex (TSR), muscular weight and volume were measured after the experiment. The TSR of in the groups A and B occurred at 4th day while in the control group it occurs at 10th day. There was statistically significant difference in SFI between groups A and B (P < 0.01). The weight and volume of the gastrocnemius muscle were statistically greater in the groups A and B than in the control group (P < 0.01). The effect of MS was similar to that of ES. It was suggested that the application of MS immediately after the nerve injury might have an important clinical value as it can accelerate functional recovery and prevent or minimize muscle atrophy. The technique is easily to operate, non-invasion, painless and permits tolerance of high intensity output to be used.

Brain-derived neurotrophic factor mediates an excitoprotective effect of dietary restriction in mice

Dietary restriction (DR; reduced calorie intake) increases the lifespan of rodents and increases their resistance to cancer, diabetes and other age-related diseases. DR also exerts beneficial effects on the brain including enhanced learning and memory and increased resistance of neurons to excitotoxic, oxidative and metabolic insults. The mechanisms underlying the effects of DR on neuronal plasticity and survival are unknown. In the present study we show that levels of brain-derived neurotrophic factor (BDNF) are significantly increased in the hippocampus, cerebral cortex and striatum of mice maintained on an alternate day feeding DR regimen compared to animals fed ad libitum. Damage to hippocampal neurons induced by the excitotoxin kainic acid was significantly reduced in mice maintained on DR, and this neuroprotective effect was attenuated by intraventricular administration of a BDNF-blocking antibody. Our findings show that simply reducing food intake results in increased levels of BDNF in brain cells, and suggest that the resulting activation of BDNF signaling pathways plays a key role in the neuroprotective effect of DR. These results bolster accumulating evidence that DR may be an effective approach for increasing the resistance of the brain to damage and enhancing brain neuronal plasticity.

N-nitrosoanilines: a new class of caspase-3 inhibitors

Caspases are a family of cysteine proteases activated during apoptosis. In cultured human endothelial cells, physiological levels of NO prevent apoptosis and interfere with the activation of the caspase cascade. Previous studies have demonstrated that NO inhibits the activity of caspase-3 by S-nitrosylation of the enzyme. In this study, the inhibitory effect of a new class of NO donors. N-nitrosoaniline derivatives, were examined against caspase-3. Initially eight small molecule inhibitors bearing N-nitroso moieties were assayed. It was found that the presence of an electron-donating group on the phenyl ring led to better inhibitory potency, a trend consistent with the results from the previous papain studies. Based on the analysis of the enzyme and substrates' structures, two peptidyl N-nitrosoaniline inhibitors [Ac-DVAD-NNO (1) and Ac-DV-AMO (2)] were designed and synthesized. Both compounds exhibited enhanced inhibitory potency against caspase-3.

Mutations in yeast ARV1 alter intracellular sterol distribution and are complemented by human ARV1

Intracellular cholesterol redistribution between membranes and its subsequent esterification are critical aspects of lipid homeostasis that prevent free sterol toxicity. To identify genes that mediate sterol trafficking, we screened for yeast mutants that were inviable in the absence of sterol esterification. Mutations in the novel gene, ARV1, render cells dependent on sterol esterification for growth, nystatin-sensitive, temperature-sensitive, and anaerobically inviable. Cells lacking Arv1p display altered intracellular sterol distribution and are defective in sterol uptake, consistent with a role for Arv1p in trafficking sterol into the plasma membrane. Human ARV1, a predicted sequence ortholog of yeast ARV1, complements the defects associated with deletion of the yeast gene. The genes are predicted to encode transmembrane proteins with potential zinc-binding motifs. We propose that ARV1 is a novel mediator of eukaryotic sterol homeostasis.

[Ecosystem management of settlement area in Xingshan County]

In the immigrant settlement area of Three-Gorges reservoir region in Xingshan County, Hubei Province, the ecological problems were the restoration of degraded ecosystem, rehabilitation of degraded crop land, and reconstruction of towns and villages. The key to the construction of the settlement area was reassigning the way of land use. The major aim of restoration of natural ecosystems should be to improve water conservation capacity of the land, because this area is located in the catchment of the Xiangxi River. The goals of management were determined as the coordinated development of both agricultural and natural forest ecosystems, the maintenance and increase of water conservation capacity of ecosystems, and the maintenance and extension of wildlife habitats. For the purpose of effective ecosystem management, the area was classified into four divisions of functional conservation region, functional rehabilitation, natural reserves and natural maintenance. The ecosystem management of the settlement area in Xingshan County was implemented in every land cell, using GIS and the typical grid-square survey method. The approach of multi-objects optimal spatial plan was developed in this paper, in which, special emphasis was put on the ecological, economic and social benefits in the construction of towns and villages. According to the scheme of management, the cover of forest in the settlement area, would increase by 30.19%, and water conservation capacity of the ecosystems would raise by 38.7%.

[The multimedia molecular biological image processing system]

With the use of computer image processing technology and molecular biological technology, we have developed a new multimedia molecular biological information processing system to detect the characteristic parameter of molecular biological electrophoresis image. The system can determine the macromolecules densities and molecular weight of the DNA amplified fragment or restriction endonuclease hydrolytic fragment protein and other macromolecules. The clinical use and biological application indicate that the system is useful to gene diagnosis and molecular biological researches.

Estrogen-induced resistance to osteoblast apoptosis is associated with increased hsp27 expression

Estrogen has been shown to protect osteoblastic cells from apoptosis. Similarly, estrogen treatment preceding heat shock elevates heat shock protein 27 (hsp27) expression and increases thermoresistance in the murine estrogen receptor-transformed SMER14 osteoblastic cell line. Forced expression of hsp27 expression in other cell lines limits apoptosis. The purpose of this study was to examine the effects of estrogen on staurosporine-induced apoptosis in the context of hsp27 expression. Cell viability was measured by the MTT assay. Early apoptotic events were examined by fluorescent microscopy by using FITC-conjugated Annexin V staining. TUNEL labeling was used to compare the number of apoptotic nuclei following staurosporine treatment of estrogen pretreated or untreated cells. Estrogen treatment increased SMER14 cell viability, but not ROS17/2.8 cell viability, in the presence of staurosporine. Estrogen treatment also reduced annexin V staining and DNA fragmentation. Similar treatment increased SMER14 cell hsp27 levels. The concurrent reduction in induced apoptosis suggests a possible estrogenic mechanism for increasing and/or maintaining the number of viable osteoblasts in bone.

Role of STAT4 and STAT6 signaling in allograft rejection and CTLA4-Ig-mediated tolerance

STAT4(-/-) mice have impaired type 1 T cell differentiation, whereas STAT6(-/-) mice fail to generate type 2 responses. The role of type 1 and type 2 T cell differentiation in acute cardiac allograft rejection and in the induction of tolerance was examined in wild-type, STAT4(-/-), and STAT6(-/-) recipients. All recipients rejected the grafts promptly. Analysis of in situ cytokine gene expression in the allografts confirmed decreased levels of IFN-gamma in STAT4(-/-) recipients and undetectable levels of IL-4 and IL-5 in STAT6(-/-) mice. Blockade of the CD28/B7 costimulatory pathway prolonged cardiac graft survival for >100 days in 100% of wild-type and STAT4(-/-) mice. However, 14% of CTLA4-Ig-treated STAT6(-/-) mice rejected their grafts between 20 and 100 days. Moreover, of those animals followed past 100 days, 60% of the STAT6(-/-) mice rejected their grafts. Splenocytes harvested on day 145 posttransplant from CTLA4-Ig-treated rejecting STAT6(-/-) recipients were transfused into syngeneic SCID mice transplanted with donor or third party cardiac allografts. Both donor and third party grafts were rejected, indicating that the initial graft loss may be due to an immunological rejection. In contrast, when splenocytes from CTLA4-Ig-treated wild-type or nonrejecting STAT6(-/-) mice were transferred into SCID recipients, donor allografts were accepted, but third party hearts were rejected. Thus, long-term prolongation of cardiac allograft survival by CTLA4-Ig is STAT4-independent but, at least in part, STAT6-dependent. These data suggest that the balance of type 1 and type 2 T lymphocyte differentiation is not critical for acute rejection but influences the robust tolerance induced by CD28/B7 blockade in this model.

Heparin-free hemodialysis in the treatment of hypernatremia in severely burned patients

BACKGROUND

Hypernatremia in severely burned patients is associated with high morbidity and mortality rates. As the causes of hypernatremia in major burn patients are still not clear, hemodialysis is the method of choice for the treatment. While hemodialysis is effective for the control of hypernatremia, it can cause bleeding complications that may be fatal for burn patients with extensive wounds and potential gastro-intestinal mucosal damage.

CLINICAL DATA

In the present study heparin-free hemodialysis in which the heparin is firmly absorbed to the haemofiltration membrane, hemophan, dispensed with systemic use of heparin. In two extensively burned patients with burn area of 100% TBSA and 98% TBSA respectively and hypernatremia with serum sodium concentration as high as 169 and 158 mmol/l respectively, heparin-free hemodialysis was performed five times and three times each.

RESULTS

Hypernatremia was satisfactorily corrected with no interference to the coagulation system in the two patients as indicated by clinical observation and biochemical analysis. The patient with burn area of 98% TBSA survived and the patient with burn area of 100% TBSA died of wound coverage failure 6 weeks after injury because of non-availability of autograft.

CONCLUSION

Heparin-free hemodialysis is an effective and safe method in the treatment of hypernatremia in extensively burned patients.