[Inhibitive effect of local perfusion of tanshinone II A nanoparticles on MMP-2 secretion]

OBJECTIVE

To test the effect of Tanshinone II A nanoparticles on the expression of MMP-2.

METHODS

Thirty five male New Zealand white rabbits were randomly divided into three groups. In group A (15 rabbits), the carotid arteries of the rabbits were stripped. In group B (5 rabbits) and C (15 rabbits), nanoparticles and Tanshinone II A nanoparticles were perfused respectively in the denudated arteries of the rabbits. The neointimal areas and the IOD values of MMP-2 secretion were measured.

RESULTS

A significant reduction of neointimal hyperplasia in group C was found compared to the other two groups in terms of the intimal area and the intima-media ratio. Group C had significant lower IOD values than group A.

CONCLUSION

Local administration of nanoparticles with incorporated Tanshinone I A not only inhibits neointimal hyperplasia but also inhibits the expression of MMP-2 in stripped arteries.

Identification of ubiquitin target proteins using cell-based arrays

A global understanding of ubiquitinated proteins in vivo is key to unraveling the biological significance of ubiquitination. There are, however, a few effective screening methods for rapid analysis of ubiquitinated proteins. In the current study, we designed a cell-based cDNA expression array combined with cell imaging for the rapid identification of polyubiquitinated proteins, which normally accumulate to form the unique "dot" structure following inhibition of ubiquitin proteasomes. The array consisted of 112 cDNAs encoding key components of major cellular pathways and potential targets of polyubiquitination. Among them, 40 proteins formed accumulation dots in response to proteasome inhibitor, MG-132, treatment. More importantly, 24 of those 40 proteins, such as MAPKAPK3, NLK, and RhoGDI2, are previously not known as the targets of ubiquitin. We further validated our findings by examining the endogenous counterparts of some of these proteins and found that those endogenous proteins form a similar "dot" structure. Immunoprecipitation assays confirmed that these accumulated proteins are polyubiquitinated. Our results demonstrate that this large-scale application of cell-based arrays represents a novel global approach in identifying candidates of the polyubiquitinated proteins. Therefore, the technique utilized here will facilitate future research on ubiquitination-regulated cell signaling.

Combined PCR-oligonucleotide ligation assay for detection of dairy cattle-derived Cyclospora sp

A rapid and sensitive assay for the detection of Cyclospora species in dairy cattle faecal specimens has been developed. The method utilizes a nested PCR to amplify a 168-bp DNA fragment of the 18S rRNA gene of cattle-derived Cyclospora sp. and an enzyme-linked immunosorbent assay (ELISA)-based oligonucleotide ligation assay (OLA) to detect the amplified product. In this study, the OLA technique was compared with conventional gel electrophoresis for the detection of amplified product. In evaluating the PCR-OLA for Cyclospora sp. and non-Cyclospora parasites, A(405) reading value for Cyclospora species was significantly higher than those for non-Cyclospora control. At known concentrations of purified amplicons from cattle-derived Cyclospora sp., the OLA was able to detect more than 0.5 ng of the amplified DNA. Of 168 clinical specimens collected from four dairy cattle farms, 6 were positive by both PCR-gel electrophoresis and the PCR-OLA procedure, and 2 were positive only by PCR-OLA, indicating the PCR-OLA procedure was more sensitive than the common way with gel electrophoresis. The results indicated that the PCR-OLA is simple, rapid and suitable in clinical detection of cattle-derived Cyclospora species.

Synthesis and QSAR studies of novel triazole compounds containing thioamide as potential antifungal agents

Eighteen novel triazole compounds containing thioamide were designed and synthesized. Their structures were confirmed by elemental analysis, (1)H NMR, IR, and MS. The title compounds exhibited certain antifungal activity. And the geometry structures of the title compounds were optimized by means of the density functional theory (DFT) method at B3LYP/6-31G( *) level. The quantitative structure-activity relationship (QSAR) of the title compounds was systematically investigated. A correlative equation between FA and DELH, V was well established by using the multiple linear regression (MLR).

Proteomics-based identification of autoantibodies in the sera of healthy Chinese individuals from Beijing

The identification of panels of tumor antigens that elicit an antibody response may have utility in cancer screening, diagnosis and in establishing prognosis. However, autoantibodies normally exist in sera of healthy individuals and are enormously diversified. To explore the reservoir of autoantibody in healthy population, we performed a proteomics investigation of autoantibody profiles in the sera of 36 healthy Chinese individuals from Beijing, which may provide valuable reference information to the identification of disease-specific autoantibodies. The results showed that autoantibody profiles varied individually, but some autoantibodies were identified at a high frequency in the healthy population. The autoantibodies against alpha-enolase and those against heterogeneous nuclear ribonucleoprotein L were positive in more than 50% of the sera samples. The autoantibodies identified in more than 20% of samples included those against annexin II, F-actin capping protein beta subunit and calreticulin. Some of these autoantibodies have been previously reported to be involved in autoimmune conditions and cancers. Autoantibodies in the healthy population are important as a foundation from which disease-specific autoantibodies can be defined. Thus our report on autoantibodies in healthy individuals may be useful as a reference for defining new autoantibody biomarkers.

MDM2 interacts with and downregulates a sarcomeric protein, TCAP

Recent reports have shown that MDM2 may attenuate hypertrophy of cardiac myocytes. However, mechanism of MDM2 involving in this process is unclear. In this study, we identified a novel specific MDM2-binding protein TCAP by the yeast two-hybrid screen. It was validated by GST pull-down and co-immunoprecipitation assays. Confocal analysis showed that MDM2 and TCAP co-localized in the nucleus, and elevated MDM2 expression could alter the subcellular localization of TCAP. Notably, MDM2 downregulated the protein level of TCAP through the proteasomal pathway, and this downregulation was inhibited by p14(ARF). In addition, our results suggested that the degradation of TCAP by MDM2 was through the ubiquitin-independent pathway. Given that TCAP is a key component involving in the cardiac hypertrophy, the degradation of TCAP by MDM2 might be connected with the roles of MDM2 in cardiac hypertrophy. Further investigation will focus on the biological significance of MDM2-TCAP interaction in cardiac hypertrophy.

Correlations of Cyclins expression types with multi-drug resistance-1 and TNM staging in gastrointestinal cancer

AIM: To investigate the expression of four Cyclins in gastrointestinal cancers, and to explore their correlations with multi-drug resistance-1 (MDR1) and TNM staging.

METHODS: Sixty-two fresh samples (gastric cancer 32, colorectal cancer 30) from patients underwent operation were collected, and the expression of Cyclin (D1, E, A, B1) and MDR1 were detected by flow cytometry. In addition, pathological reports were analyzed for TNM staging.

RESULTS: According to the expression of four Cyclins, four cell cycle types were divided in the gastrointestinal cancers. These four cell cycle types were in accordance with TNM staging (κ = 0.599, P < 0.01) and marked correlation with the level of MDR1 expression (r_s = 0.495, P < 0.01).

CONCLUSION: Cell cycle typing based on Cyclins expression has the same significance as TNM staging. MDR1 expression is correlated with the cell cycle typing, so it is possible to reverse MDR through interfering in cell cycle.

Pleomorphic adenoma of the lacrimal gland in a nine-year-old child

A case of a 9-year-old child with pleomorphic adenoma of the lacrimal gland is described. This tumour is usually found in adults; cases younger than 10 years of age have proved to be extremely rare. Because of its age distribution, pleomorphic adenoma of the lacrimal gland is usually overlooked as a possible cause of unilateral proptosis in children. Also, the history of disease provided by the family may be incorrect, possibly leading to misdiagnosis by the ophthalmologist.

[Cell balance between apoptosis and proliferation in colon cancer and its correlation with prognosis]

BACKGROUND & OBJECTIVE

In normal tissues and organs, cell apoptosis and proliferation maintain a homeostasis. Alterations of this physiologic balance may lead to malignant transformation of cells and tumorigenesis. This study was to investigate cell balance (ratio of apoptosis index to proliferation index, AI/PI) in colon cancer and its correlation with prognosis.

METHODS

The apoptotic population and the proliferating population of colon cancer cells were quantitatively analyzed by Sub-G1 method and Ki-67/DNA bivariate analysis of flow cytometry. Cell proliferation was observed under confocal microscope. Kaplan-Meier method and log-rank test were used to analyze patients' survival.

RESULTS

AI/PI ratio of cells was significantly higher in normal colon tissue than in colon adenoma tissue, Dukes' A colon cancer, Dukes' B colon cancer, and Dukes' C and D colon cancer (0.45+/-0.19 vs. 0.30+/-0.07, 0.29+/-0.11, 0.28+/-0.10, and 0.26+/-0.07, respectively, P < 0.01). AI/PI ratio showed a down-regulating trend in variables tested including tumor size, pathologic type, differentiation grade, Dukes' stage, and nodal involvement. AI/PI ratio of peripheral lymphocytes was significantly higher in colon cancer patients than in healthy people (0.64+/-0.11 vs. 0.49+/-0.12, P < 0.01). The expression of Ki-67 was observed in normal colon tissue, colon adenoma, and colon cancer under confocal microscope. Survival rate of patients with AI/PI ratio of < 0.285 (using the median value as the cutoff) and >/= 0.285 was not significantly different (P> 0.05).

CONCLUSIONS

Dysregulation (down-regulation or up-regulation) of cell balance between apoptosis and proliferation in colon cancer cells and lymphocytes might play an important role in tumorigenesis and tumor progression. AI/PI ratio can' t be used as a prognostic factor of colon cancer.

Balance of cell apoptosis and proliferation and its association with related genes in gastric cancer

AIM: To investigate the balance between cell proliferation and apoptosis in gastric cancer and their association with related genes.

METHODS: Sixty-eight surgically resected samples were collected between 2000 and 2001, including 10 normal gastric tissues, 10 para-cancerous tissues, and 48 gastric carcinoma tissues from pathologically confirmed patients(32 males and 16 females, aged 24-74 years with mean age 54.4 years). The patients did not receive chemotherapy or radiotherapy. All of the samples were fixed in 40 g/L formalin, embedded in paraffin, and sliced into 4 mm-thick sections. The apoptotic cells and proliferative cells were quantitatively analyzed by flow cytometry. Immunohistochemical assay (SP method) was used to detect the expression of survivin, Fas and FasL. The morphology of proliferating cells was identified by confocal microscope.

RESULTS: In the normal, para-cancerous and tumor groups, the ratio of apoptosis and proliferation indexes (AI/PI) were 0.46 ± 0.14, 0.35 ± 0.12, and 0.23 ± 0.11, respectively. The difference was significant (F = 19.453, P < 0.01). Normal distribution was observed by frequency distribution of AI/PI in gastric carcinoma cells. Tumors exhibited a wide range of AI/PI from 0.05 to 0.46. Overall, the median and mean ± SD of AI/PI were 0.245 and 0.23 ± 0.11, respectively. The value of Skewness and Kurtosis were 0.067 and -0.868, respectively. A stepwise decreasing trend in AI/PI was noted in clinicopathological variables, including lymph node metastasis and beyond metastasis(P < 0.05 for each). Granular staining was observed in both the cytoplasm and cell membrane of survivin, Fas and FasL positive cells. The expression rates of survivin, Fas and FasL in 48 gastric cancer were 56.2%, 43.8% and 60.4%, respectively. Using the median AI/PI of 0.245, we divided the cells into two groups(greater than and less than the median AI/PI). The expression of survivin and FasL in >0.245 were significantly lower than that of < 0.245. On the contrary, the expression of Fas in >0.245 was significantly higher than that of < 0.245. The high expression of ki-67 in tumor was found by confocal microscope.

CONCLUSION: A stepwise decreasing trend in AI/PI may exist in tumor progression, which might be correlated with the up-regulation of survivin gene and the down-regulation of Fas gene.

Thomson scattering measurements of heat flux from ion-acoustic waves in laser-produced aluminum plasmas

Thomson scattering (TS) measurements are performed at different locations in a laser-produced aluminum plasma. Variations of the separation, wavelength shift, and asymmetric distribution of the two ion-acoustic waves are investigated from their spectral-time-resolved TS images. Detailed information on the space-time evolution of the plasma parameters is obtained. Electron distribution and variation of the heat flux in the plasma are also obtained for a steep temperature gradient.

[Raman spectra and photoluminescence spectra of InGaN/GaN multiquantum wells annealed]

InGaN/GaN multiquantum well, grown by MOCVD on a sapphire substrate and annealed under the conditions of 700 and 900 degrees C x (20 min)(-1), was studied by means of mirco-Raman spectroscopy and photoluminescence. The Raman peak of E2, A1 showed red shift after multiquantum were wells annealed, and the HWHM of Raman peakdecreased imperceptibly. Moreover,the photoluminescence peak of the sample annealed under the condition of 700 degrees x (20 min)(-1) showed a red shift, then appeared a blue shift under the condition of 900 degrees C x (20 min)(-1). These results clearly showed that the sample annealed induced strain stress relief that could explain Raman peak shift, but the piezoelectric field induced the quantum-confined Stark effect, which can't agree with the photoluminescence experiment. Sample annealed could change the width of quantum well and InGa phase segregated; these factors influencing structure of quantum well could explain the results of photoluminescence spectra.

Specific heat and Lindemann-like parameter of metallic clusters: Mono- and polyvalent metals

The Brownian-type molecular dynamics simulation is revisited and applied to study the thermal and geometric properties of four mono- and two polyvalent metallic clusters. For the thermal property, we report the specific heat at constant volume CV and study the solid-liquid-like transition by scrutinizing its characteristic. For the geometric property, we calculate the root mean square relative bond-length fluctuation delta as a function of increasing temperature. The thermal change in delta reflects the movement of atoms and hence is a relevant parameter in understanding the phase transition in clusters. The simulated results for the CV of alkali and aluminum clusters whose ground state structures exhibit icosahedral symmetry generally show one phase transition. In contrast, the tetravalent lead is quite often seen to exhibit two phase transitions, a premelting process followed by a progressive melting. In connection with the premelting scenario, it is found here that those (magic number) clusters identified to be of lesser stability (among other stable ones) according to the second energy difference are clusters showing a greater possibility of undergoing premelting process. This energy criterion applies to aluminum clusters nAl=28 and 38. To delve further into the thermal behavior of clusters, we have analyzed also the thermal variation of deltaT and attempted to correlate it with CV(T). It turns out that the premelting (if exist) and melting temperatures of the smaller size clusters (n less, similar 50) extracted from CV do not always agree quantitatively with that deduced from delta.

[Application of one-way valved patch in treatment of patients with congenital heart disease with severe pulmonary hypertension]

OBJECTIVE

To explore the effect of one-way valved patch used in congenital heart disease with severe pulmonary hypertension.

METHODS

One-way valved patch was used in 30 patients of congenital heart disease with severe pulmonary hypertension (PP/PS > 0.75) in operation. Follow-up of 6 approximately 86 months was conducted to observe its effect.

RESULTS

The pulmonary artery pressure was significantly decreased without trans-patch shunt in 11 cases postoperatively. Trans-patch shunt was determined in 27 cases within postperative 72 hours. There were 2 postoperative deaths out of these 27 patients: one died of low cardiac output syndrome 72 hours after operation, and the other died of right heart failure 4 weeks after operation. Thirty-six patients were restored to health and discharged. Three-month follow-up showed trans-patch shunt in 7 cases, including right-to left shunt in 4 cases and two-side shunt in other 3 cases. Color Doppler ultrasonography conducted 6 months after operation proved trans-patch shunt in 4 cases, right-to-left shunt in 1 case, two-side shunt in 2 cases, and left-to-right shunt in 1 case (PP/PS = 0.45).

CONCLUSION

One-way valved patch is useful in selected patients in which postoperative right heart failure can be anticipated so as to shunt the blood in the right heart to the left heart and increase the blood volume in the left heart system to ensure the left heart output and minimize the risk of postoperative right heart failure, at the expense of systemic low oxygen saturation that is, however, well tolerated.

[Energy transfer between electric polymer PVK and terbium complex and its transmission electronmicroscope (TME) study]

A chloroform-soluble terbium complex, which is confirmed to be Tb(aspirin)3 phen using element analysis and FT-IR spectroscopy, was synthesized. Photoluminescent investigation on the terbium complex and PVK-terbium complex composite was conducted. Förster energy transfer occurred between the terbium complex and the PVK matrix. There are no overlap between UV spectrum of the complex and the emission spectrum of PVK, however, overlap is observed between the excitation spectrum of the complex and the emission spectrum of PVK. Therefore, we suggest that the necessary condition of Förster energy transfer should be overlap between the excitation (not UV) spectrum of one complex and the emission spectrum of polymer matrix. Further investigation indicates that the emission of PVK can be suppressed at different extents by doping various amount of Tb(aspirin)3 phen into PVK films. The ratio of Tb(aspirin)3 phen: PVK = 1:2 (wt%) are regarded as an optimized ratio for limiting the emission of PVK. TEM images of PVK/Tb(aspirin)3 phen films reveal that nanoparticles of the Tb complex are dispersed in the PVK matrix. The size of the aggregated complex in PVK matrix is 20-30 nm. The film is not homogeneous as dark regions co-exist with light region in the TEM images. This phenomenon may be related to the short lifetime of electroluminescent devices.

Genomic divergence between human and chimpanzee estimated from large-scale alignments of genomic sequences

To study the genomic divergence between human and chimpanzee, large-scale genomic sequence alignments were performed. The genomic sequences of human and chimpanzee were first masked with the RepeatMasker and the repeats were excluded before alignments. The repeats were then reinserted into the alignments of nonrepetitive segments and entire sequences were aligned again. A total of 2.3 million base pairs (Mb) of genomic sequences, including repeats, were aligned and the average nucleotide divergence was estimated to be 1.22%. The Jukes-Cantor (JC) distances (nucleotide divergences) in nonrepetitive (1.44 Mb) and repetitive sequences (0.86 Mb) are 1.14% and 1.34%, respectively, suggesting a slightly higher average rate in repetitive sequences. Annotated coding and noncoding regions of homologous chimpanzee genes were also retrieved from GenBank and compared. The average synonymous and nonsynonymous divergences in 88 coding genes are 1.48% and 0.55%, respectively. The JC distances in intron, 5' flanking, 3' flanking, promoter, and pseudogene regions are 1.47%, 1.41%, 1.68%, 0.75%, and 1.39%, respectively. It is not clear why the genetic distances in most of these regions are somewhat higher than those in genomic sequences. One possible explanation is that some of the genes may be located in regions with higher mutation rates.

Transposable elements are found in a large number of human protein-coding genes

To study the genome-wide impact of transposable elements (TEs) on the evolution of protein-coding regions, we examined 13 799 human genes and found 533 (approximately 4%) cases of TEs within protein-coding regions. The majority of these TEs (approximately 89.5%) reside within 'introns' and were recruited into coding regions as novel exons. We found that TE integration often has an effect on gene function. In particular, there were two mouse genes whose coding regions consist largely of TEs, suggesting that TE insertion might create new genes. Thus, there is increasing evidence for an important role of TEs in gene evolution. Because many TEs are taxon-specific, their integration into coding regions could accelerate species divergence.

NJML+: an extension of the NJML method to handle protein sequence data and computer software implementation

While the maximum-likelihood (ML) method of tree reconstruction is statistically rigorous, it is extremely time-consuming for reconstructing large trees. We previously developed a hybrid method (NJML) that combines the neighbor-joining (NJ) and ML methods and thus is much faster than the ML method and improves the performance of NJ. However, we considered only nucleotide sequence data, so NJML is not suitable for handling amino acid sequence data, which requires even more computer time. NJML+ is an implementation of a further improved method for practical data analyses (including protein sequence data). Our extensive simulations using nucleotide and amino acid sequences showed that NJML+ gave good results in tree reconstruction. Indeed, NJML+ showed substantial improvements over existing methods in terms of both computational times and efficiencies, especially for amino acid sequence data. We also developed a "user-friendly" interface for the NJML+ program, including a simple tree viewer.

Isolation of Cladonema Pax-B genes and studies of the DNA-binding properties of cnidarian Pax paired domains

Pax genes encode nuclear transcription factors that are involved in developmental control. They contain a conserved DNA-binding domain, the paired domain. The DNA-binding specificity of paired domains is directly related to the gene regulation function of Pax proteins. Pax genes were previously divided into five groups on the basis of a phylogenetic analysis of paired domains. In this study, two highly similar cnidarian Pax-B genes from Cladonema californicum, a jellyfish with eyes, were found and sequenced. In an effort to understand the function of the cnidarian Pax genes isolated in this and a previous study, we characterized the consensus DNA sequences bound by the cnidarian paired domains using a PCR-based method and electrophoretic mobility shift assays. The consensus DNA sequences obtained are very similar to those bound by mammalian Pax proteins. Comparison of known consensus sequences indicates that they are all partially palindromic, but this characteristic is most prominent in cnidarians, which suggests that the DNA sequences bound by the ancestral paired domain could have been palindromic. Also, cnidarian paired domains, like those of Pax-2/5/8, possess a broader binding specificity than other paired domains, which implies that the common ancestor of Pax-2/5/8 and Pax-4/6 paired domains could also have had a similar broad DNA-binding specificity. Thus far, a definitive Pax-6 gene has not been found in several cnidarian species examined, which is consistent with a later origin of the Pax-6 gene and raises two possibilities: the Pax genes of cnidarians are multifunctional and control two or more developmental pathways, including eye development, or they use a Pax-independent pathway for eye development. Whether this pathway does exist and is unique to cnidarians or it whether it represents a true master control under which Pax-6 was later included remains to be determined.

[A biomechanical model of left ventricle regional ischemia: a computer simulation]

Objective. To analyze the biomechanical mechanism of left ventricular regional ischemia and to investigate the changes of myocardial contractilities in different ventricular regions during regional ischemia. Method. A time-dependent mathematical model for simulating left ventricle regional ischemia has been developed basing on geometry of left ventricle, spatial angle distribution, propagation of electrical activation signals and biomechanical properties of cardiac muscle fibers. Then the model was incorporated into a multi-element circulatory model established by us previously. By using this model, some simulation experiments relating myocardium contractility to regional ischemia in inner or outer layers of ventricular wall were performed. Result. Myocardial contractility of the ischemic layers decreased whereas that of normal layers increased significantly. Compared with ischemia in outer layers of ventricular wall, ischemia in inner layers of ventricular wall had more effects upon cardiac function. Conclusion. The myocardium of normal region had the ability to increase its contractility in order to maintain a normal cardiac function. A method to simulate the relationship between cardiovascular function and left ventricular regional ischemia was developed.

Human DNA sequence variation in a 6.6-kb region containing the melanocortin 1 receptor promoter

An approximately 6.6-kb region located upstream from the melanocortin 1 receptor (MC1R) gene and containing its promoter was sequenced in 54 humans (18 Africans, 18 Asians, and 18 Europeans) and in one chimpanzee, gorilla, and orangutan. Seventy-six polymorphic sites were found among the human sequences and the average nucleotide diversity (pi) was 0.141%, one of the highest among all studies of nuclear sequence variation in humans. Opposite to the pattern observed in the MC1R coding region, in the present region pi is highest in Africans (0.136%) compared to Asians (0.116%) and Europeans (0.122%). The distributions of pi, theta, and Fu and Li's F-statistic are nonuniform along the sequence and among continents. The pattern of genetic variation is consistent with a population expansion in Africans. We also suggest a possible phase of population size reduction in non-Africans and purifying selection acting in the middle subregion and parts of the 5' subregion in Africans. We hypothesize diversifying selection acting on some sites in the 5' and 3' subregions or in the MC1R coding region in Asians and Europeans, though we cannot reject the possibility of relaxation of functional constraints in the MC1R gene in Asians and Europeans. The mutation rate in the sequenced region is 1.65 x 10(-9) per site per year. The age of the most recent common ancestor for this region is similar to that for the other long noncoding regions studied to date, providing evidence for ancient gene genealogies. Our population screening and phylogenetic footprinting suggest potentially important sites for the MC1R promoter function.

Episodic Evolution of Growth Hormone in Primates and Emergence of the Species Specificity of Human Growth Hormone Receptor

Growth hormone (GH) evolution is very conservative among mammals, except for primates and ruminant artiodactyls. In fact, most known mammalian GH sequences differ from the inferred ancestral mammalian sequence by only a few amino acids. In contrast, the human GH sequence differs from the inferred ancestral sequence by 59 amino acids. However, it is not known when this rapid evolution of GH occurred during primate evolution or whether it was due to positive selection. Also, human growth hormone receptor (GHR) displays species specificity; i.e., it can interact only with human (or rhesus monkey) GH, not with nonprimate GHS: The species specificity of human GHR is largely due to the Leu-->Arg change at position 43, and it has been hypothesized that this change must have been preceded by the His-->Asp change at position 171 of GH. Is this hypothesis true? And when did these changes occur? To address the above issues, we sequenced GH and GHR genes in prosimians and simians. Our data supported the above hypothesis and revealed that the species specificity of human GHR actually emerged in the common ancestor of Old World primates, but the transitional phase still persists in New World monkeys. Our data showed that the rapid evolution of primate GH occurred during a relatively short period (in the common ancestor of higher primates) and that the rate of change was especially high at functionally important sites, suggesting positive selection. However, the nonsynonymous rate/synonymous rate ratio at these sites was <1, so relaxation of purifying selection might have played a role in the rapid evolution of the GH gene in simians, possibly as a result of multiple gene duplications. Similar to GH, GHR displayed an accelerated rate of evolution in primates. Our data revealed proportionally more amino acid replacements at the functionally important sites in both GH and GHR in simians but, surprisingly, showed few coincidental replacements of amino acids forming the same intermolecular contacts between the two proteins.