Biomedical subjects

J Peng

Publications and source records attributed to J Peng.

At least 37 records · Page 2Linked to original sources

PubMed2003

Age-related variation in quantitative ultrasound at the tibia and prevalence of osteoporosis in native Chinese women.

This study investigated the variations in age-related speed of sound (SOS) at the tibia and prevalence of osteoporosis in native Chinese women, and establishment of a reference database by quantitative ultrasound. SOS at the right midtibia was measured using a quantitative ultrasound device (SoundScan 2000, Myriad Ultrasound Systems, Israel) in 1596 healthy Chinese women ranging from 12 years to 96 years of age. Healthy women were selected on the basis of (1). a detailed questionnaire about their medical history, (2). face to face questioning about their medical history, and (3). a physical examination. Women with a medical condition that required medication that affected bone metabolism or those who had had a pathologic or moderate traumatic fracture were excluded. We followed the diagnostic criteria provided by the instrument's manufacturer and equivalent to the WHO criteria (using the T-score cut-off that diagnoses 30% of the post-menopausal women aged >or =50 years with osteoporosis) as the diagnostic criteria for osteoporosis in this group of women. Data were analyzed in age groups divided by intervals of 5 years. The peak SOS at the tibia of 3991+/-68 m s(-1) (mean+/-SD) occurred in the 35-39 year age group and the T-score precision was 0.99 T-score units. The SOS value increased with age up to 34 years of age and then declined with age after 40 years of age with the rate of decrease at 9.68 m s(-1) per year. The curve representing the SOS change according to age is best fitted by the regression analysis of cubic model, and the cubic equation for SOS=3383+39.9 (age)-0.78 (age)(2)+0.0039 (age)(3) (R(2)=0.505, p=0.000). The T-score cut-off that diagnoses 30% of the post-menopausal women (n=559, mean age 63.2+/-8.97 years) aged >or=50 years with osteoporosis was SOS or=80 years, the prevalences of osteoporosis detected using equivalent to the WHO criteria were 0.39%, 9.27%, 30.3%, 58.4% and 69.0%, respectively. The prevalences detected following the manufacturer's diagnostic criteria (cut-off value: SOS<or=3800 m s(-1), T-score<or=-2.0) were 3.14%, 20.5%, 53.2%, 78.8% and 89.7%, respectively. There were significant differences in the prevalence between the diagnostic criteria in the various age groups (p=0.000-0.002). In 769 women from 40 years to 59 years of age, the mean SOS was significantly higher in pre-menopausal women (n=500) than in post-menopausal women (n=269) (3977+/-89 vs 3881+/-118 m s(-1), p=0.000). The prevalence of osteoporosis in these women was 0.40% in pre-menopausal women, 8.92% in post-menopausal women, respectively. There were significant differences in prevalence of osteoporosis between the two groups of pre- and post-menopausal women (p=0.000). In conclusion, SOS at tibia can provided useful information about bone status in the normative population of native Chinese women for determination of osteoporosis. The reference database based on these data will be appropriate for the diagnosis of osteoporosis by tibial quantitative ultrasound in native Chinese women.

Adolescent↗

PubMed2003

Differential linkage of triglyceride and glucose levels on rat chromosome 4 in two segregating rat populations.

The PD/Cub is a recently established model of the IRS. The BN.SHR4 congenic strain was derived by introgression of the chromosome 4 segment of SHR origin (including the defective Cd36/Fat allele) onto the BN/Cub genetic background. We investigated the linkage of metabolic and morphometric phenotypes (total body weight, OGTT, fasting serum levels of TG, FFA) on chromosome 4 in two separate F2 rat populations: the PD/Cub x BN/Cub and PD/Cub x BN.SHR4 (total N = 243). In the PD/Cub x BN.SHR4 F2s, we found significant linkage for fasting TG levels (LOD = 3.26) and suggestive linkage for fasting glycaemia (LOD = 2.80) in the interval Il-6 - D4Bro1, i.e. the part of chromosome 4 of SHR origin in the BN.SHR4 congenic. However, no linkage for fasting TG concentrations, fasting glycaemia or any other followed parameter was found in the second, PD/Cub x BN/Cub F2. The differential linkage of TG and glucose levels to the centromeric part of rat chromosome 4q in the studied F2s points to the importance of this region for the lipid and carbohydrate metabolism at the specific age (10 months) and diet (standard chow) combination. The Cd36/Fat and Il-6 genes are the preliminary positional candidates for the observed effect.

Animals↗

PubMed2003

Cancer incidence and mortality in France over the period 1978-2000.

BACKGROUND: Monitoring cancer incidence and mortality time trends is essential for cancer research and health-care planning. French cancer registries do not cover the entire population and do not provide a representative sample of the national population. Our study aimed at estimating national cancer incidence and mortality trends over the longest period available. METHODS: Incidence and mortality data were collected over the period 1978-1997. Twenty-seven cancer sites were selected and age, sex and site specific incidence and mortality rates were estimated for each year from 1978 up to 2000. Observed incidence and mortality data in the population covered by cancer registries were modelled using age-cohort methods. An estimation of the incidence/mortality ratio was obtained from these models and applied to the mortality rates predicted from an age-cohort model for the entire French population. The person-years of observation were calculated cohort-wise from census data provided by the national institute of statistics RESULTS: Cancer incidence increased by 63% throughout the study period, from 170,000 new cases in 1980 to 278,000 in 2000. This evolution was due to demographic changes but also to an increase in the risk of cancer which was estimated to more than 35% during the same period. In men, this change is largely explain by the increase of prostate cancer incidence. Among women, the increase was dominated by the continuing increase in breast cancer incidence. Large increases were also seen for non-Hodgkin lymphoma, melanoma, and thyroid cancer in both genders and for lung cancer in women. Cancer mortality increased by 20% from 125,000 deaths in 1980 to 150,000 in 2000. This increase is less than that predicted from changes in demographic factors and corresponds in fact to a decrease in the risk of death estimated to about 8%, slightly greater for women than for men. This decrease is associated with a decreasing incidence for stomach cancers for both sexes, alcohol-related cancer for men and cervical cancer for women. Colo-rectal cancer decreasing mortality contributes to this improvement despite an incidence increase. CONCLUSION: Between 1980 and 2000, the study showed a large change in the cancer burden both quantitatively and qualitatively. Decrease in exposure, earlier diagnosis and therapeutic improvement explained part of this change, but overall the distribution of cancer cases shifted toward a distribution including less aggressive cancers. A striking divergence between incidence and mortality trends is observed for a great number of cancers. Prostate cancer shares with breast cancer the same pattern of a severe increasing incidence and a stable mortality. This points to important changes in medical practice and needs further analysis. The trend of lung cancer mortality among women should be emphasised since the situation will inevitably worsen in the coming years. It is already the third cause of cancer death among women.

Age Distribution↗

PubMed2002

Endothelium-dependent vasorelaxation and the expression of calcitonin gene-related peptide in aged rats.

To explore the age-related change in endothelium-dependent vasorelaxation, plasma concentrations and the expression of calcitonin gene-related peptide (CGRP) as well as serum concentrations of asymmetry dimethylarginine (ADMA), male Sprague-Dawley rats, aged 6 and 24 months were tested. The level of ADMA and CGRP in blood, and CGRP mRNA in dorsal root ganglia (DRG) were determined by high-performance liquid chromatography (HPLC), radioimmunoassay or semi-quantitative reverse-transcription polymerase chain reaction, respectively. Vasodilator responses to cumulative concentrations of acetylcholine (ACh) (3 x 10(-9) - 3 x 10(-7)M) and CGRP (3 x 10(-10) - 3 x 10(-8)M) were tested at the plateau of contraction in aortas rings. Vasodilator responses to ACh or CGRP at 24 months of age were decreased compared with 6 months. The serum concentration of ADMA at 24 months of age was significantly increased compared with 6 months, while both plasma concentrations of CGRP and the expressions of alpha- and beta-CGRP mRNA were unchanged at two age groups. The results suggest that endothelium-dependent relaxation, but not concentrations and the expressions of CGRP, is decreased in aged rats, and the decrease in endothelium dependence of vasodilator response to CGRP may be related to the elevation of endogenous ADMA.

Aging↗

PubMed2002

In vivo pharmacodynamics of a new oxazolidinone (linezolid).

Linezolid is a new oxazolidinone with activity against gram-positive cocci. We determined the in vivo activity of linezolid against four strains of Staphylococcus aureus (two methicillin-susceptible S. aureus [MSSA] strains and two methicillin-resistant S. aureus strains) and one penicillin-susceptible Streptococcus pneumoniae (PSSP) strain, two penicillin-intermediate S. pneumoniae strains, and five penicillin-resistant S. pneumoniae strains. The mice had 10(6.3) to 10(7.7) CFU/thigh before therapy and were then treated for 24 h with 5 to 1,280 mg of linezolid/kg divided into 1, 2, 4, 8, or 16 doses. The killing activities after 4 h of therapy ranged from 2.4 to 5.0 log(10) CFU/thigh against S. pneumoniae and 1.35 to 2.2 log(10) CFU/thigh against S. aureus. Increasing doses produced minimal concentration-dependent killing; doses of 20 and 80 mg/kg produced no in vivo postantibiotic effects (PAEs) with PSSP and modest PAEs (3.4 and 3.2 h) with MSSA. Pharmacokinetic studies at doses of 20 and 80 mg/kg by high-pressure liquid chromatography analysis exhibited peak dose values of 0.68 and 0.71 and elimination half-lives of 1.02 and 1.00 h. Linezolid MICs ranged from 0.5 to 1.0 micro g/ml for S. pneumoniae and from 1.0 to 4.0 micro g/ml for S. aureus. A sigmoid dose-response model was used to estimate the dose required to achieve a net bacteriostatic effect over 24 h. Static doses against S. pneumoniae ranged from 22.2 to 97.1 mg/kg/24 h and from 133 to 167 mg/kg/24 h for S. aureus. The 24-h area under the concentration-time curve (AUC)/MIC ratio was the major parameter determining the efficacy of linezolid against PSSP (R(2) = 82% for AUC/MIC versus 57% for T>MIC and 59% for the peak level in serum/MIC [peak/MIC]). It was difficult to determine the most relevant pharmacokinetic/pharmacodynamic parameter with S. aureus, although the outcomes correlated slightly better with the 24-h AUC/MIC ratio (R(2) = 75%) than with the other parameters (T>MIC R(2) = 75% and peak/MIC R(2) = 65%). The 24-h AUC/MIC ratio required for a bacteriostatic effect with linezolid varied from 22 to 97 (mean = 48) for pneumococci and from 39 to 167 (mean = 83) for staphylococci. Based upon a pharmacokinetic goal of a 24-h AUC/MIC of 50 to 100, a dosage regimen of 600 mg given either intravenously or orally twice daily would achieve success against organisms with MICs as high as 2 to 4 micro g/ml.

Acetamides↗

PubMed2002

[Incidence and prevalence estimations for breast and colorectal cancer in the Picardy region].

OBJECTIVES: To provide incidence and prevalence data on breast and colorectal cancer in the Picardie area of France. METHODS: An age-period-cohort method was used to estimate regional incidence and prevalence of cancer from regional cancer mortality data and patient survival data recorded in the Somme Cancer Registry. RESULTS: European standardized breast incidence for 1998 was 110 per 100000 inhabitants. The incidence for colorectal cancer was 67 per 100000 for men and 47 per 100000 for women. Prevalence was 9656 for breast cancer and 6283 (2941 for men and 3342 for women) for colorectal cancer. Incidence of breast cancer increased considerably (80.9%) between 1979 and 1998. CONCLUSION: These results provide data on breast cancer and colorectal cancer which are useful for planning demand for healthcare or medical surveillance in the Picardie area.

Adult↗

PubMed2001

Cloning and characterization of human and mouse mitochondrial elongation factor G, GFM and Gfm, and mapping of GFM to human chromosome 3q25.1-q26.2.

Similar to the translational system in the cell cytoplasm, the initiation, elongation, and termination of protein synthesis in the mitochondria of eukaryotes are catalyzed by several protein factors. These factors, from the viewpoint of evolution, are more closely related to the corresponding prokaryotic factors than to those in the eukaryotic cytoplasm. In this paper, we isolated two cDNAs coding for human and mouse mitochondrial elongation factor G (GFM and Gfm, respectively). The GFM cDNA, which is 3481 bp in length, predicts a protein of 751 amino acids sharing 84 and 42% identity and 88 and 62% similarity to rat EF-G(mt) and Escherichia coli EF-G, respectively, and 24% identity and 39% similarity to human EF-2, the equivalent of EF-G in the cytoplasm. The mouse Gfm cDNA is 2564 bp and contains an intact open reading frame that encodes 751 amino acids showing 89% sequence identity and 94% similarity to human GFM. Northern blot analysis of human GFM revealed three transcripts of 3.8, 3.4, and 2.9 kb. The first two were expressed at high levels in heart, skeletal muscle, and testis, at moderate levels in liver and kidney, and at low levels in other tissues including brain, placenta, and lung, while the last transcript was expressed only in testis. The relative abundance of GFM was consistent with the observations for human EF-Tu(mt) and EF-Ts(mt), the other two mitochondrial elongation factors, indicating that the three factors were expressed at corresponding levels. The expression pattern of mouse Gfm was also determined, which showed that Gfm was expressed as a 3.0-kb transcript, abundantly in heart, skeletal muscle, kidney, and testis. In addition, GFM was assigned to human chromosome 3q25.1-q26.2 by the radiation hybrid mapping method. The genomic organization of GFM was also analyzed by comparing this cDNA with a genomic DNA sequence (Accession No. AC010936), which showed that GFM contained 18 exons and spanned at least 40 kb.

Amino Acid Sequence↗

PubMed2001

Rh type B glycoprotein is a new member of the Rh superfamily and a putative ammonia transporter in mammals.

Ammonium transporters play a key functional role in nitrogen uptake and assimilation in microorganisms and plants; however, little is known about their structural counterpart in mammals. Here, we report the molecular cloning and biochemical characterization of Rh type B glycoproteins, human RhBG and mouse Rhbg, two new members of the Rh family with distinct tissue specificities. The RhBG orthologues possess a conserved 12-transmembrane topology and most resemble bacterial and archaeal ammonium transporters. Human RHBG resides at chromosome 1q21.3, which harbors candidate genes for medullary cystic kidney disease, whereas mouse Rhbg is syntenic on chromosome 3. Northern blot and in situ hybridization revealed that RHBG and Rhbg are predominantly expressed in liver, kidney, and skin, the specialized organs involving ammonia genesis, excretion, or secretion. Confocal microscopy showed that RhBG is located in the plasma membrane and in some intracellular granules. Western blots of membrane proteins from stable HEK293 cells and from mouse kidney and liver confirmed this distribution. N-Glycanase digestion showed that RhBG/Rhbg has a carbohydrate moiety probably attached at the NHS motif on exoloop 1. Phylogenetic clustering, tissue-specific expression, and plasma membrane location suggest that RhBG homologous proteins are the long sought major ammonium transporters in mammalians.

Amino Acid Sequence↗

PubMed2001

Proteomics: the move to mixtures.

Proteomics can be defined as the systematic analysis of proteins for their identity, quantity and function. In contrast to a cell's static genome, the proteome is both complex and dynamic. Proteome analysis is most commonly accomplished by the combination of two-dimensional gel electrophoresis (2DE) and mass spectrometry (MS). However, this technique is under scrutiny because of a failure to detect low-abundance proteins from the analysis of whole cell lysates. Alternative approaches integrate a diversity of separation technologies and make use of the tremendous peptide separation and sequencing power provided by MS/MS. When liquid chromatography is combined with tandem mass spectrometry (LC/MS/MS) and applied to the direct analysis of mixtures, many of the limitations of 2DE for proteome analysis can be overcome. This tutorial addresses current approaches to identify and characterize large numbers of proteins and measure dynamic changes in protein expression directly from complex protein mixtures (total cell lysates).

Electrophoresis, Gel, Two-Dimensional↗

PubMed2001

Acidolysis and hot water extraction provide new insights into the composition of the induced "lignin-like" material from squash fruit.

Accumulation of "lignin-like" material (L-LM) by plant tissues in response to injury or disease has been observed in a wide variety of plant taxa. The most intensively studied L-LM is that produced by members of the Cucurbitaceae; this material is thought to be an unusual lignin rich in p-coumaryl alcohol derived subunits. Employing acidolysis we found the primary degradation product of L-LM from squash fruit was p-coumaryl aldehyde. These findings conflict with the current concept of L-LM, but would be consistent with L-LM being a polymer derived directly from p-coumaryl aldehyde or a gum containing this compound. Results of hot water extraction support the latter possibility. Further, we report on a simple TLC method useful for rapid qualitative characterization of acidolysis degradation products.

Chromatography, Thin Layer↗

PubMed2001

Structure and regulation of the CDK5-p25(nck5a) complex.

CDK5 plays an indispensable role in the central nervous system, and its deregulation is involved in neurodegeneration. We report the crystal structure of a complex between CDK5 and p25, a fragment of the p35 activator. Despite its partial structural similarity with the cyclins, p25 displays an unprecedented mechanism for the regulation of a cyclin-dependent kinase. p25 tethers the unphosphorylated T loop of CDK5 in the active conformation. Residue Ser159, equivalent to Thr160 on CDK2, contributes to the specificity of the CDK5-p35 interaction. Its substitution with threonine prevents p35 binding, while the presence of alanine affects neither binding nor kinase activity. Finally, we provide evidence that the CDK5-p25 complex employs a distinct mechanism from the phospho-CDK2-cyclin A complex to establish substrate specificity.

Amino Acid Sequence↗

PubMed2001

Probing the conformational state of a truncated staphylococcal nuclease R using time of flight mass spectrometry with limited proteolysis.

The conformational state of C-terminally truncated staphylococcal nuclease R (SNR135), with and without bound ligands, has been studied by performing limited proteolysis with a specific endoproteinase Glu-C followed by electrophoresis and mass spectrometry. Comparison of the accessibility of the cleavage sites shows that the C-terminal truncation of 14 amino-acid residues causes significant unfolding of the C-terminal part of alpha helix 1 and the center of alpha helix 2, but there is little effect on other regions of the nuclease, in particular the N-terminal subdomain, which includes the active site of the nuclease. The truncation also makes the overall conformation of the nuclease more loose and flexible. Binding of ligands makes helices 1 and 2 more resistant to protease Glu-C attack and converts the partially unfolded state to a native-like state, although the conformational stability of the SNR135 complex is still much lower than that of the full-length enzyme. The results suggest that the amino-acid residues around the active site in the truncated nuclease are arranged in a similar topology to those in the full-length nuclease. The study shows that there is a clear-cut correlation between protease susceptibility and conformational stability of the protein, and the initial proteolytic events are the most critical for evaluating the conformational features of the protein. This study demonstrates how mass spectrometry can be combined with limited proteolysis to observe conformational changes induced by ligand binding.

Binding Sites↗

PubMed2001

Enhanced efficiency of quantitative trait loci mapping analysis based on multivariate complexes of quantitative traits.

An approach to increase the efficiency of mapping quantitative trait loci (QTL) was proposed earlier by the authors on the basis of bivariate analysis of correlated traits. The power of QTL detection using the log-likelihood ratio (LOD scores) grows proportionally to the broad sense heritability. We found that this relationship holds also for correlated traits, so that an increased bivariate heritability implicates a higher LOD score, higher detection power, and better mapping resolution. However, the increased number of parameters to be estimated complicates the application of this approach when a large number of traits are considered simultaneously. Here we present a multivariate generalization of our previous two-trait QTL analysis. The proposed multivariate analogue of QTL contribution to the broad-sense heritability based on interval-specific calculation of eigenvalues and eigenvectors of the residual covariance matrix allows prediction of the expected QTL detection power and mapping resolution for any subset of the initial multivariate trait complex. Permutation technique allows chromosome-wise testing of significance for the whole trait complex and the significance of the contribution of individual traits owing to: (a) their correlation with other traits, (b) dependence on the chromosome in question, and (c) both a and b. An example of application of the proposed method on a real data set of 11 traits from an experiment performed on an F(2)/F(3) mapping population of tetraploid wheat (Triticum durum x T. dicoccoides) is provided.

Chromosome Mapping↗

PubMed2001

Interval cancers in a French breast cancer-screening programme (Somme Department).

The objective of this study is to analyse the detection rates and tumour diameter of interval cancers in the breast cancer mass-screening programme of Somme Department (France), launched in 1990. Interval cancers are defined as breast cancers diagnosed within 36 months after a negative screening assessment, for women attending the programme between December 1990 to December 1993. Age-adjusted incidence rates were 0.51 per 1000 woman-years of follow-up in the 3-year interval after initial and subsequent screens. Diagnosis is made at early stage (sizes < or = 10 mm) in 20% of interval cancers. This stage is higher than that in screened women (9% of in situ cases and 35% of very small tumours). Interval cancer rates are low during the first year (0.18 per 1000 woman-years of follow-up) but higher in the second and third years.

Aged↗

PubMed2001

Expression of Arabidopsis GAI in transgenic rice represses multiple gibberellin responses.

Bioactive gibberellins (GAs) are essential endogenous regulators of plant growth. GA signaling is mediated via GAI, a nuclear member of the GRAS family of plant transcription factors. Previous experiments have suggested that GAI is a GA-derepressible repressor of plant growth. Here we test this hypothesis by examining the effects of the expression of Arabidopsis GAI in transgenic Basmati rice. High-level expression of GAI caused dwarfism and reduced GA responses, and the strength of this effect was correlated with the level of transgene expression. In particular, the expression of GAI abolished the GA-mediated induction of rice aleurone alpha-amylase activity, thus implicating GAI orthologs in the well-characterized cereal aleurone GA response. The GA derepressible repressor model predicts that high-level expression of GAI should confer dwarfism, and these observations are consistent with this prediction.

Arabidopsis↗

PubMed2001

Computer-aided dynamic simulation of microwave-induced thermal distribution in coagulation of liver cancer.

To develop a method of dynamic three-dimensional (3-D) simulation of thermal distribution in ultrasound-guided microwave coagulation therapy of liver cancer and to verify its accuracy. The specific absorption rate (SAR) values were established by measuring the temperature in equivalent phantom tests. Those values were different under different power output condition. Dynamic 3-D temperature distributions were reconstructed with a finite-element model. Testing and rectification were performed through animal experiments and clinical trials, respectively. The temperature curves in the experiments corresponded well with simulated ones in vitro--91.4% and 88.9% using single and double electrodes, respectively. The measured coagulated boundary and simulated temperature boundary had a good correspondence in 85.7% of the specimens. In both in vivo experiments and clinical trials, blood perfusion influenced the rise in temperature significantly. Temperature curves between the simulations and actual measured results showed good correspondence--67.8% (19/28) in the patients with hepatocellular carcinoma. Distance between electrodes and combined thermal distributions were both optimized with computer-aided simulation during simultaneous two-electrode coagulation. The results demonstrated that computer-aided simulation of microwave thermal distribution is an accurate and reliable method which provides a theoretical and technical basis for controlling coagulated tissue volume and placement of the electrodes during microwave coagulation therapy of liver cancer.

Animals↗

PubMed2001

[Association of apolipoprotein E gene polymorphism with early-onset coronary heart disease and its effect on plasma lipid levels].

OBJECTIVE: To detect the association of apolipoprotein E(apoE) gene polymorphism with early-onset coronary heart disease(CHD) and to evaluate the effect of apoE gene polymorphism on plasma lipid levels. METHODS: The apoE genotypes of 52 early-onset CHD patients (aged 38-55 years), 161 aged CHD patients and 180 controls were determined by PCR-RFLP. Plasma lipid levels were measured by using routine methods. RESULTS: Five genotypes of apoE, E3/3, E4/4, E3/2, E4/3 and E4/2 were detected in this study. Statistically differences in apoE4/3 and epsilon4 frequencies between early-onset and aged CHD patients and controls were seen (P<0.05). The frequency of epsilon4 in the early-onset CHD patients was higher than that in the aged CHD patients. epsilon4 and epsilon2 alleles also differently affected the plasma total cholesterol and low density lipoprotein cholesterol levels. CONCLUSION: These results suggest that apoE gene polymorphism is in association with the occurrence and development of early-onset CHD and it affects the plasma lipid levels.

Adult↗

PubMed2001

Telomerase activity and homozygous deletions of the p16 gene in liver metastases of colorectal carcinoma.

OBJECTIVE: To study the interaction between telomerase activity and abnormalities of the p16 gene in liver metastases of colorectal carcinoma. METHODS: Telomerase activity was detected by a non-isotopic PCR-based telomeric repeat amplification protocol (TRAP) assay, and homozygous deletions of the p16 gene were detected by a semiquantitative multiplex polymerase chain reaction in tissue samples from 24 liver metastases of colorectal carcinoma and 5 primary colorectal carcinomas. RESULTS: Telomerase activity was observed in 19 (79.2%) of 24 liver metastases of colorectal carcinoma. Telomerase activity was also observed in all 5 primary colorectal carcinomas and in 3 of their liver metastatic samples. The incidence of telomerase activity in liver metastases of colorectal carcinoma was not significantly correlated to tumor diameter, number of tumors, cirrhosis, and HBsAg. Homozygous deletions of the p16 gene were found in 9 of 24 (37.5%) liver metastases of colorectal carcinoma. Homozygous deletions of the p16 gene were observed in 2 of the 5 primary colorectal carcinomas and in 1 of the matching liver metastatic cancers. There was a correlation between telomerase activity and homozygous deletions of the p16 gene. CONCLUSIONS: There is a correlation between telomerase activity and homozygous deletions of the p16 gene in liver metastases of colorectal carcinoma, suggesting its crucial role in liver metastases. However, telomerase activation and homozygous deletions of the p16 gene might not be the initiating event in liver metastases of colorectal carcinoma.

Colorectal Neoplasms↗