Accurate diagnosis of colorectal cancer based on histopathology images using artificial intelligence

BACKGROUND

Accurate and robust pathological image analysis for colorectal cancer (CRC) diagnosis is time-consuming and knowledge-intensive, but is essential for CRC patients' treatment. The current heavy workload of pathologists in clinics/hospitals may easily lead to unconscious misdiagnosis of CRC based on daily image analyses.

METHODS

Based on a state-of-the-art transfer-learned deep convolutional neural network in artificial intelligence (AI), we proposed a novel patch aggregation strategy for clinic CRC diagnosis using weakly labeled pathological whole-slide image (WSI) patches. This approach was trained and validated using an unprecedented and enormously large number of 170,099 patches, > 14,680 WSIs, from > 9631 subjects that covered diverse and representative clinical cases from multi-independent-sources across China, the USA, and Germany.

RESULTS

Our innovative AI tool consistently and nearly perfectly agreed with (average Kappa statistic 0.896) and even often better than most of the experienced expert pathologists when tested in diagnosing CRC WSIs from multicenters. The average area under the receiver operating characteristics curve (AUC) of AI was greater than that of the pathologists (0.988 vs 0.970) and achieved the best performance among the application of other AI methods to CRC diagnosis. Our AI-generated heatmap highlights the image regions of cancer tissue/cells.

CONCLUSIONS

This first-ever generalizable AI system can handle large amounts of WSIs consistently and robustly without potential bias due to fatigue commonly experienced by clinical pathologists. It will drastically alleviate the heavy clinical burden of daily pathology diagnosis and improve the treatment for CRC patients. This tool is generalizable to other cancer diagnosis based on image recognition.

Development and characterization of new microsatellite markers of Fenneropenaeus penicillatus

Thirteen new polymorphic microsatellite markers in Fenneropenaeus penicillatus were isolated and characterized. The polymorphism of the thirteen microsatellite markers was tested by 30 individuals from Lianjiang, China. It showed that the number of al-leles per locus ranged from 3 to 6 and the Polymorphism Information Content (PIC) was from 0.324 to 0.706. The observed and expected heterozygosities were 0.3217-0.8023 and 0.1977-0.6783, respectively. Only one loci (LJ-19) deviated significantly from Hardy-Weinberg equilibrium (HWE) (P < 0.00385) after Bonferroni correction, while the other twelve markers were in HWE after Bonferroni correction (P > 0.00385). The thirteen polymorphic microsatellite markers could pro-vide more genetic data for further research on cultivation and recovery of F. penicillatus.

Isolation of new polymorphic microsatellite markers from the marbled rockfish Sebastiscus marmoratus

The marbled rockfish, Sebastiscus marmoratus, is an important commercially near-shore fish that inhabits the beach rocky bottom from Japan to the South China Sea. Eleven polymorphic microsatellite loci were developed from S. marmoratus and were used to identify polymorphisms in 30 samples from a wild population. The allele locus number ranged from 2 to 7. Polymorphism data content ranged from 0.032 to 0.751. The observed and expected heterozygosity levels were 0.0333-0.9667 and 0.0328-0.7675, respectively. Two loci, Smd1-112 and Smd2-80, deviated from Hardy-Weinberg equilibrium. These polymorphic microsatellite markers will facilitate further studies of genetic diversity and genetic differentiation of S. marmoratus.

Development and characterization of polymorphic microsatellite loci in the sea cucumber Holothuria leucospilota

Holothuria leucospilota is a tropical holothurian species that is widely distributed in the tropical and sub-tropical India-Western Pacific Region. Eight polymorphic microsatellite loci were developed from H. leucospilota by using the protocol fast isolation by amplified fragment length polymorphism of sequences containing repeats and tested in 30 individuals from Hainan Island in China. The number of alleles was 2-6 and polymorphism information content ranged from 0.371-0.694. The levels of expected and observed heterozygosities varied from 0.3913-0.6701 and from 0.1154-0.7000, respectively. No significant linkage disequilibrium was detected for any pairwise combination of loci. Only loci YZHS1-42 deviated from Hardy-Weinberg equilibrium. These polymorphic microsatellite loci may be useful for germplasm conservation of H. leucospilota.

No evidence of association of the osteocalcin gene HindIII polymorphism with bone mineral density in Chinese women

Osteoporosis is a major health problem, mainly characterized by low bone mineral density (BMD). Osteocalcin (also known as BGP, for bone Gla protein) is a significant biomarker of bone turnover and thus the BGP gene has been considered as an important candidate gene for osteoporosis. A few studies on the relationship between variants of the BGP gene and BMD variation, via traditional association and/or linkage methods, have yielded conflicting results. In the present study, we simultaneously tested linkage and/or association of the BGP HindIII polymorphism with BMD in a large cohort of pre-menopausal Chinese women. A total of 1,263 subjects from 402 Chinese nuclear families were examined. Each family consists of both parents and at least one daughter aged between 20-45 years. BMDs at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative transmission disequilibrium test) program, we did not detect significant evidence of linkage or association between the BGP HindIII polymorphisms and the BMD variation at any skeletal site. Our data do not support the BGP gene having a major effect on BMD variation in pre-menopausal Chinese women.

Ethnic difference in osteoporosis-related phenotypes and its potential underlying genetic determination

Osteoporosis is a serious health problem in both Caucasians and Asians. Caucasians and Asians are two distinct major ethnic groups, which may have differential genetic determination underlying complex genetic diseases such as osteoporosis. However, to date, there has been no systematic review focusing on the aspect of ethnic difference in risk to osteoporosis and its potential underlying genetic determination between Asians and Caucasians. Here, we firstly review diverse aspects of osteoporosis-related differences, including the differences of epidemiology of osteoporotic fractures, peak bone mass, bone loss, bone area, bone geometry and drug treatment response between Asians and Caucasians. Then, we provide some potential genetic evidence on the different heritability and inheritance mode of bone phenotypes, the different osteoporosis candidate genes and the differential results in related molecular studies between them, to explain the above osteoporosis-related phenotypic differences. The results suggest that the osteoporosis-related phenotypic differences between Asians and Caucasians may be partially the result of the different ethnic genetic background. The present review may increase our understanding of potential different mechanisms related to ethnicity in pathogenesis of osteoporosis for effective and potentially customized treatments in different major ethnic groups.

Molecular and genetic mechanisms of osteoporosis: implication for treatment

Osteoporosis is a leading public health problem in our rapidly growing, aging population. It is characterized by reduced bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture risk. Osteoporosis is a complex multifactorial disease, determined by genetic and environmental factors as well as their interactions. A large number of molecular, genetic and environmental factors underlying osteoporosis have been identified in past decades. In this article, we review 1) the molecular mechanisms of several principal systemic and local factors regulating bone metabolism; and 2) the current status of genetic studies searching for genes underlying osteoporosis. Further, we attempt to integrate knowledge from those two fields, and their potential implications for osteoporosis treatment.

Association of estrogen receptor alpha and vitamin D receptor gene polymorphisms with bone mineral density in Chinese males

Osteoporosis is a common health problem not only in females but also in males, however, studies of osteoporosis in males are relatively rare compared to those in females. This is especially true in genetics studies. We evaluated the effects of PvuII and XbaI polymorphisms in the estrogen receptor alpha (ER-alpha) gene and ApaI polymorphism in the vitamin D receptor (VDR) gene on BMD variation in a random sample of 352 unrelated males from 401 Chinese nuclear families. BMD was measured at the lumbar spine (L1-L4) and hip (femoral neck, trochanter, intertrochanteric region). Raw BMD values were adjusted by age, age(2), height, and weight as covariates. We found no significant results for the 3 individual markers on BMD variation, however, ER-alpha haplotype analyses yielded some interesting results. Carriers of haplotype pX had a 4.98% lower BMD at the trochanter (P = 0.02) and 3.55% lower BMD at the lumbar spine (P = 0.09) than non-carriers. PX subjects had a 3.42% higher BMD at the trochanter and 3.26% higher BMD at the lumbar spine than others (P = 0.07 and P = 0.10, respectively). Such results were highly comparable with the significant or nearly significant interactions between ER-PvuII and ER-XbaI on BMD values at the trochanter (P = 0.03) and spine (P = 0.11). No significant results were observed for the interactions between ER-PvuII and VDR-ApaI, between ER-XbaI and VDR-ApaI, and between any of ER-alpha haplotypes and VDR-ApaI locus. Our results suggest that the ER-alpha haplotypes, not individual markers, may be associated with BMD variation at some skeletal sites in our Chinese male samples.

Gene mapping and identification for osteoporosis

Osteoporosis is a disease characterized by fragile bones and high susceptibility to low trauma fractures. It is a serious health problem, especially in elderly women. Bone mineral density (BMD) has been employed most commonly as the index for defining and studying osteoporosis. In this presentation, we use examples of our studies in both Caucasians and Chinese to illustrate the approaches used and some main results obtained on 1) characterizing the degree and the inheritance mode of genetic determination of a complex trait such as BMD; 2) identifying and mapping genes for osteoporosis. The purpose of the presentation is to introduce to the medical researchers how and what modern genetics can do to disentangle the mist of an array of genetics factors, the major determinants, for BMD.

Complex segregation analyses of bone mineral density in Chinese

China has the largest population in the world; approximately 7% of the total population suffers from primary osteoporosis. Osteoporosis is mainly characterized by low bone mineral density (BMD). In the present study, familial correlation and segregation analyses for spine and hip BMDs have been undertaken for the first time in a Chinese sample composed of 401 nuclear families with a total of 1260 individuals. The results indicate a major gene of additive inheritance for hip BMD, whereas there is no evidence of a major gene influencing spine BMD. Significant familial residual effects are found for both traits, and heritability estimates (+/-SE) for spine and hip BMDs are 0.807(0.099) and 0.897(0.101), respectively. Sex and age differences in genotype-specific average BMD are also observed. This study provides the first evidence quantifying the high degree of genetic determination of BMD variation in the Chinese.

Tests of linkage and association of the COL1A2 gene with bone phenotypes' variation in Chinese nuclear families

In the present study, we simultaneously test linkage and/or association of the collagen type I alpha 2 (COL1A2) gene with bone mineral density (BMD) and bone area. A total of 1280 subjects from 407 Chinese nuclear families (including both parents and their daughters) were genotyped for an intragenic marker MspI in the COL1A2 gene. BMD and bone area at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry. Applying the QTDT (quantitative transmission disequilibrium test) program, we performed tests for population stratification, within-family association (via transmission disequilibrium test), total association, linkage, and linkage while modeling association. Significant or marginal within-family associations were found with BMD at the lumbar spine (P = 0.013), trochanter (P = 0.004), and total hip (P = 0.053) and with bone area at the intertrochanteric region (P = 0.024) and total hip (P = 0.048). The positive associations were confirmed in permutations except for bone area at total hip (P > 0.10). A small proportion (<1%) of the population variance of bone phenotypes can be explained by the MspI polymorphism; however, it may be underestimated given the significant population stratification detected in our sample. Due to the limited number of sib pairs in this sample, we did not find evidence of linkage. In summary, the MspI polymorphism is likely to be in linkage disequilibrium with a nearby functional mutation affecting BMD and bone area.

No evidence for linkage and/or association of human alpha2-HS glycoprotein gene with bone mineral density variation in Chinese nuclear families

Osteoporosis is an important health problem in the world. Alpha2-HS glycoprotein (AHSG) is involved in bone formation and metabolism and has been considered as an important candidate gene for osteoporosis. In this study, we simultaneously tested linkage and/or association of the AHSG gene with the variation of bone mineral density (BMD), an important risk factor for osteoporosis. A sample of 1,260 subjects from 401 Chinese nuclear families (including both parents and their daughters) were studied. The daughters' ages ranged from 20 to 45 years. All the subjects were genotyped by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) at polymorphic Sac I site inside the exon 7 of the AHSG gene. This polymorphism involves a nucleotide substitution of C to G at the middle nucleotide of the codon at amino acid position 238, resulting in the replacement of threonine (ACC) with serine (AGC). BMD was measured at the lumbar spine and hip region by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative trait transmission disequilibrium test), we found no significant results for association or linkage between the AHSG gene and BMD variation at the spine or hip. Our data provided no evidence to support the AHSG gene as a quantitative trait locus (QTL) for the BMD variation in a Chinese population.

Evidence for a major gene for bone mineral density/content in human pedigrees identified via probands with extreme bone mineral density

Bone mineral content (BMC) and/or bone mineral density (BMD, i.e. BMC scaled by bone size) are major determinants for osteoporosis, which is a serious health problem. The major determinant of variation in BMD/BMC is genetic. The few studies now available are inconsistent in the identification and/or even in the existence of major gene(s) for BMD/BMC. In 51 human pedigrees with 941 individuals (526 measured for phenotypes) identified via probands with extreme BMD values, we performed complex segregation analyses to test the existence of a genetic locus with a major effect on BMD/BMC variation. We analyzed BMD and BMC at the spine, hip and wrist jointly by employing, as the study phenotype, factor scores (FS) of the principle component that explains approximately 75% of the total BMD/BMC variation at the three sites. The results indicate that a major gene exists with a codominant effect that is responsible for approximately 16% of the FS variation when adjusted for significant effects of sex, body weight and age. A significant genotype-x-sex-x-age interaction was found, which may explain approximately 14% of the FS variation after adjusting for body weight. Testing of various models did not provide support for shared familial environmental effects but suggested the existence of residual polygenic effects, which may explain approximately 50% of the FS variation when adjusting for sex, body weight and age. This study indicates a promising aspect of studies to identify a major gene for BMD/BMC variation in our pedigrees identified via extreme probands.

Improvement of preservation with cardioplegic solution by nitroglycerin-induced delayed preconditioning is mediated by calcitonin gene-related peptide

Improvement of preservation with cardioplegic solution by nitroglycerin-induced delayed preconditioning was studied in the isolated rat heart. The isolated rat heart was arrested using St. Thomas Hospital solution, and then reperfused with normothermic Krebs-Henseleit solution for 40 min after a 4-h hypothermic ischemic period. Heart rate, coronary flow, left ventricular pressure and the maximum value of the first derivatives of left ventricular pressure (+/-dp/dt(max)) were recorded, and plasma concentrations of CGRP-like immunoreactivity (CGRP-LI) and nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha) in myocardial tissues, and creatine kinase in coronary effluent were measured. Delayed preconditioning was induced by i.v. injection of nitroglycerin 24 h before the experiment. Nitroglycerin (60 microg/kg or 120 microg/kg) caused an improvement of cardiac function, a decrease in the release of creatine kinase in coronary effluent and a decrease in the content of TNF-alpha in myocardial tissues. Nitroglycerin significantly increased plasma concentrations of CGRP and NO. After pretreatment with capsaicin, which depletes neurotransmitters in sensory nerves, or methylene blue, a selective guanylate cyclase inhibitor, the protection and the elevated release of CGRP induced by nitroglycerin were abolished. The present study suggests that improvement of preservation with cardioplegic solution by nitroglycerin-induced delayed preconditioning is due to stimulation of CGRP release in the rat heart, and that the protection of CGRP-mediated nitroglycerin is related to inhibition of TNF-alpha production.

The power of the transmission disequilibrium test (TDT) with both case-parent and control-parent trios

The transmission disequilibrium test (TDT) customarily uses affected children and their parents (often case-parent trios, TDTD). Control-parent trios are necessary to guard against spurious significant results due to segregation distortion but are not generally utilized in the identification of disease susceptibility loci (DSL). Controls are often easy to recruit and the TDT can easily be extended to include control-parent trios into the analyses with unrelated case-parent trios. We present an extension of the TDT (TDTDC) that incorporates unrelated cases and controls and their parents into a single analysis. We develop a simple and accurate analytical method for computing the statistical power of various TDT (e.g. the TDTD, TDTDC, TDTDC and TDTC that employ control-parent trios only) under any genetic model. We investigated the power of these TDT, and particularly compared the relative power of the TDTD and TDTDC. We found that the TDTDC is almost always more powerful than the TDTC and TDTD. The relative power of the TDTDC and TDTD depends largely upon a number of parameters identified in the study. This study provides a basis for efficient use of control-parent trios in DSL identification.

Effect of asymmetric dimethylarginine on osteoblastic differentiation

BACKGROUND

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase (NOS) that accumulates in renal insufficiency and may be a uremic toxin. To determine whether ADMA inhibits bone metabolism, we investigated the in vitro effect of ADMA on osteoblastic differentiation in mouse bone marrow-derived mesenchymal stem cells (BMSCs).

METHODS

The effect of ADMA on nitric oxide (NO) production was determined by measuring the stable end product of NO, nitrite, in the culture medium using commercial NO kit. The temporal sequence of osteoblastic differentiation in BMSCs was assessed in the presence and absence of ADMA by measuring alkaline phosphatase (ALP) activity, mineralization, and osteoblast gene expression at 0, 4, 8, 12 days of culture.

RESULTS

ADMA (5, 50, 500 micromol. L-1) resulted in a dose-dependent decrease in nitrite formation in conditioned media of BMCS cultures, consistent with inhibition of NOS. ADMA treatment was associated with reduced ALP activity, calcium deposition and osteoblast-related gene expression in BMSCs cultures. Concurrent treatment with l-arginine (3600 micromol. L-1) reversed the ADMA (500 micromol. L-1)-mediated decrease in NO production, restored the differentiation potential of BMSCs, and significantly attenuated the down-regulation of Cbfa1 and osteocalcin gene expression by ADMA.

CONCLUSIONS

ADMA inhibition of the NO-NOS pathway in BMSCs impairs osteoblastic differentiation of mouse BMSC cultures. These studies further support a role of NO in the local regulation of bone metabolism and the possibility that ADMA may act as uremic toxin on bone through its effect to inhibit NO actions in osteoblasts.

Population admixture may appear to mask, change or reverse genetic effects of genes underlying complex traits

Association studies using random population samples are increasingly being applied in the identification and inference of genetic effects of genes underlying complex traits. It is well recognized that population admixture may yield false-positive identification of genetic effects for complex traits. However, it is less well appreciated that population admixture can appear to mask, change, or reverse true genetic effects for genes underlying complex traits. By employing a simple population genetics model, we explore the effects and the conditions of population admixture in masking, changing, or even reversing true genetic effects of genes underlying complex traits.

Effect of polygenes on Xiong's transmission disequilibrium test of a QTL in nuclear families with multiple children

The transmission disequilibrium test (TDT), originally developed for mapping disease genes, has recently been extended to identify quantitative trait loci (QTL). For quantitative traits important for human health, generally multiple QTLs are involved. In the investigation of the statistical properties of the TDT, background polygenes (QTLs other than the QTL under test) generally have not been explicitly considered. The effects of background polygenes on the statistical properties of the TDT are thus largely unknown. Investigation of these effects will provide more realistic analyses of the statistical properties of the TDT under biologically plausible situations, and thus provide more accurate guidelines on the application of the TDT in practice. A general TDT (TDT(G)) has been developed to test linkage of a QTL in nuclear families that may be composed of more than one heterozygous parent and multiple children. Using the TDT(G) as an example, we develop an analytical method to investigate the effects of background polygenes on the power of the TDT. The accuracy of our analytical method is validated by computation simulations. We found that the power of the TDT(G) is increased with background polygenes when more than one child is employed in nuclear families, and the effect is stronger with more children per family recruited for study. The power of the TDT(G) increases dramatically when the number of children recruited from each nuclear family increases from one to two or from two to three. The type one error rate is not affected by the presence of background polygenes. The results of this study should be of theoretical significance in generalizing the investigation of the TDT to biologically plausible situations with background polygenes. They should also be of practical values in providing guidance on the recruitment of nuclear families with multiple children with the TDT(G).

Elevated serum endogenous inhibitor of nitric oxide synthase and endothelial dysfunction in aged rats

1. The purpose of the present study was to determine the relationship between endothelial dysfunction and the endogenous inhibitor of nitric oxide synthase NG,NG'-asymmetric dimethylarginine (ADMA) in aged rats. 2. Studies were performed in male adult Sprague-Dawley rats (6 months old; n = 8) and in aged rats (20 months old; n = 8). Serum levels of ADMA and L-arginine were measured by high-performance liquid chromatography and responses of endothelium-intact aortic rings to acetylcholine (ACh) were tested. Nitric oxide synthase activity in kidney tissue and serum concentrations of nitrite, a stable end-product of nitric oxide, were assayed and serum contents of malondialdehyde, derived from lipid peroxidation and serum lipid and creatinine level were determined. 3. Serum levels of ADMA increased significantly in aged rats compared with adult rats (P < 0.01), whereas serum levels of L-arginine were similar in both groups (P = NS). Accordingly, the ratio of L-arginine/ADMA in old rats was lower than that in young rats (P < 0.01). Endothelium-dependent relaxation responses to ACh in aortic rings from aged rats were impaired and these impaired responses were improved by pre-incubation of aortic rings with L-arginine. 4. Nitric oxide synthase activity in the kidney, together with serum concentration of nitrite, was significantly decreased and serum contents of malondialdehyde, cholesterol and triglycerides were increased in old compared with young rats. However, the serum creatinine level was not significantly different between adult and aged rats. 5. Endogenous ADMA may be a contributor to age-related endothelial dysfunction and increases in endogenous ADMA may be linked to lipid peroxidation in aged rats.

Induction of alpha-calcitonin gene-related peptide mRNA expression in rat dorsal root ganglia by heat stress involves the heme oxygenase-1/carbon monoxide pathway

SD rats were pretreated with whole body hyperthermia (rectal 42 degrees C) for 15 min. The level of calcitonin gene-related peptide (CGRP) in plasma, and alpha- and beta-CGRP mRNA as well as heme oxygenease-1 and heme oxygenase-2 mRNA in dorsal root ganglia were determined by radioimmunoassay and semi-quantitative reverse-transcription polymerase chain reaction, respectively. Heat stress induced only the expression of alpha-CGRP or heme oxygenease-1 but not beta-CGRP or heme oxygenase-2 mRNA, and the release of CGRP and induction of alpha-CGRP mRNA expression were abolished by pretreatment with Zinc protoporphyrin IX, the heme oxygenase inhibitor, or methylene blue, the inhibitor of soluble guanylate cyclase. These results indicate that induction of alpha-CGRP mRNA expression in rat DRG by heat stress involves the heme oxygenase-1/carbon monoxide pathway.

Delayed cardioprotection by intestinal preconditioning is mediated by calcitonin gene-related peptide

Previous studies have shown that nitric oxide and calcitonin gene-related peptide (CGRP) are involved in mediation of the delayed cardioprotection of ischemic or pharmacological preconditioning, and nitric oxide can evoke the release of CGRP. In the present study, we examined the role of CGRP in nitric oxide-mediated delayed cardioprotection by brief intestinal ischemia in rats. The serum concentration of creatine kinase and infarct size were measured after 45-min coronary artery occlusion and 180-min reperfusion. Ischemic preconditioning was induced by six cycles of 4-min ischemia and 4-min reperfusion of the small intestine. Pretreatment with intestinal ischemic preconditioning for 24, 48, or 72 h significantly reduced infarct size and creatine kinase release, and the effects of ischemic preconditioning were completely abolished by L-nitroarginine methyl ester (L-NAME, 10 mg/kg, i.p.), an inhibitor of nitric oxide synthase, or by pretreatment with capsaicin (50 mg/kg, s.c.), which selectively depletes transmitters in capsaicin-sensitive sensory nerves. Intestinal preconditioning caused a significant increase in plasma concentrations of CGRP, and the effect was also abolished by L-NAME or capsaicin. These results suggest that the delayed cardioprotection afforded by intestinal ischemic preconditioning is mediated by endogenous CGRP via the nitric oxide pathway.

Involvement of calcitonin gene-related peptide in the development of tolerance to nitroglycerin in the rat

Previous studies have shown that the depressor effect of nitroglycerin is related to stimulation of endogenous calcitonin gene-related peptide (CGRP) release. In the present study, we explored whether endogenous CGRP is involved in the development of tolerance to nitroglycerin in the rat. Tolerance was induced by treatment with nitroglycerin (10 mg/kg, subcutaneous [s.c.]) three times a day for 8 days and confirmed by a reduction in hypotensive responses to intravenous (i.v.) nitroglycerin. Nitroglycerin (30 or 150 microg/kg, i.v.) significantly decreased blood pressure concomitantly with an increase in plasma concentration of nitric oxide (NO) and CGRP, and these effects of nitroglycerin disappeared after pretreatment with nitroglycerin for 8 days. However, the nitroglycerin-induced depressor effect and elevation of NO and CGRP content were restored, partially or completely, 4 or 8 days after nitroglycerin removal in the tolerant rat. The present study suggests that the development of tolerance to nitroglycerin is related to the decreased release of CGRP in the rat.

Role of calcitonin gene-related peptide in nitric oxide-mediated myocardial delayed preconditioning induced by head stress

AIM

To study the role of calcitonin gene-related peptide (CGRP) in nitric oxide (NO)-mediated myocardial delayed preconditioning induced by heat stress.

METHODS

The isolated rat heart was perfused in a Langendorff model. Hearts for all groups were subjected to 4 h hypothermia (4 degrees C) and 40 min reperfusion (37 degrees C). In the hyperthermia-treated group, rats were subjected to whole-body hyperthermia (rectal 42 degrees C, 15 min) 24 h before the experiment. Heart rate, coronary flow, left ventricular pressure, and its derivative (+/- dp/dtmax) were recorded, and calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in plasma and the activity of creatine kinase (CK) in the coronary effluent were measured.

RESULTS

Pretreatment with hyperthermia significantly improved the recovery of cardiac protection, reduced the release of CK, and increased plasma concentrations of CGRP. Pretreatment with L-NAME, an inhibitor of NOS, or capsaicin, which selectively depleted sensory neurotransmitter content, abolished the protective effects and the increased level of CGRP elicited by hyperthermia.

CONCLUSION

Endogenous NO is involved in the cardioprotection afforded by heat stress, and the beneficial effects of NO are mediated by CGRP in the rat.

The depressor effect of nitroglycerin is mediated by calcitonin gene-related peptide

Previous investigations have suggested that vasodilator responses to nitroglycerin involve in stimulation of calcitonin gene-related peptide (CGRP) release. Therefore, we tested whether depressor effect of nitroglycerin is mediated by CGRP. A catheter was inserted into the left femoral artery to record blood pressure and drugs were administered through cannulae inserted into the right femoral vein. Nitroglycerin (15, 30, 60, 120 and 150 microg/kg) caused depressor effects in a dose-dependent manner. Nitroglycerin (30 or 150 microg/kg) caused a depressor effect with an increase in plasma concentrations of CGRP. The effects of nitroglycerin were significantly attenuated by methylene blue, an inhibitor of guanylate cyclase, or by pretreatment with capsaicin (50 mg x kg(-1), s.c.), which depletes neurotransmitters in sensory nerves. The present study suggests that the depressor effect of nitroglycerin is related to stimulation of CGRP release in the rat.

Is population bone mineral density variation linked to the marker D11S987 on chromosome 11q12-13?

Our purpose is to test linkage of human chromosome 11q12-13 to BMD variation. Chromosome 11q12-13 has been linked to three BMD-related phenotypes that are inherited as Mendelian traits in human pedigrees: an autosomal dominant high bone mass trait, autosomal recessive osteoporosis pseudoglioma, and autosomal recessive osteopetrosis. A sibling pair study with 374 sibships showed significant linkage of D11S987 to normal BMD variation, with a maximum logarithm of odds score of 3.5. However, a subsequent linkage study with a total of 595 sibling pairs demonstrated reduced significance for linkage of D11S987 to bone mineral density variation, with a logarithm of odds score less than 2.2. We genotyped five markers in a genomic region of approximately 27 cM centering on D11S987 and measured bone mineral density and other traits (weight, etc.) for 635 individuals from 53 human pedigrees. Each of these pedigrees was ascertained through a proband with bone mineral density Z-scores less than -1.28 at the hip or spine. Adjusting for age, sex, and weight as covariates, we performed two-point and multipoint linkage analyses using the variance component linkage analysis method implemented in Sequential Oligogenic Linkage Analysis Routines. We found little evidence of linkage of these five markers to bone mineral density at the spine, hip, wrist and total body bone mineral content. The maximum logarithm of odds score at these five markers was 0.25, and the maximum logarithm of odds score at D11S987 was 0.15. Therefore, although we cannot exclude the linkage of D11S987 region to bone mineral density variation, there is no evidence for linkage of the marker D11S987 on human chromosome 11q12-13 to bone mineral density variation in our study population.

Toward high-throughput genotyping: dynamic and automatic software for manipulating large-scale genotype data using fluorescently labeled dinucleotide markers

To efficiently manipulate large amounts of genotype data generated with fluorescently labeled dinucleotide markers, we developed a Microsoft database management system, named. offers several advantages. First, it accommodates the dynamic nature of the accumulations of genotype data during the genotyping process; some data need to be confirmed or replaced by repeat lab procedures. By using, the raw genotype data can be imported easily and continuously and incorporated into the database during the genotyping process that may continue over an extended period of time in large projects. Second, almost all of the procedures are automatic, including autocomparison of the raw data read by different technicians from the same gel, autoadjustment among the allele fragment-size data from cross-runs or cross-platforms, autobinning of alleles, and autocompilation of genotype data for suitable programs to perform inheritance check in pedigrees. Third, provides functions to track electrophoresis gel files to locate gel or sample sources for any resultant genotype data, which is extremely helpful for double-checking consistency of raw and final data and for directing repeat experiments. In addition, the user-friendly graphic interface of renders processing of large amounts of data much less labor-intensive. Furthermore, has built-in mechanisms to detect some genotyping errors and to assess the quality of genotype data that then are summarized in the statistic reports automatically generated by. The can easily handle >500,000 genotype data entries, a number more than sufficient for typical whole-genome linkage studies. The modules and programs we developed for the can be extended to other database platforms, such as Microsoft SQL server, if the capability to handle still greater quantities of genotype data simultaneously is desired.

A general and accurate approach for computing the statistical power of the transmission disequilibrium test for complex disease genes

Transmission disequilibrium test (TDT) is a nuclear family-based analysis that can test linkage in the presence of association. It has gained extensive attention in theoretical investigation and in practical application; in both cases, the accuracy and generality of the power computation of the TDT are crucial. Despite extensive investigations, previous approaches for computing the statistical power of the TDT are neither accurate nor general. In this paper, we develop a general and highly accurate approach to analytically compute the power of the TDT. We compare the results from our approach with those from several other recent papers, all against the results obtained from computer simulations. We show that the results computed from our approach are more accurate than or at least the same as those from other approaches. More importantly, our approach can handle various situations, which include (1) families that consist of one or more children and that have any configuration of affected and nonaffected sibs; (2) families ascertained through the affection status of parent(s); (3) any mixed sample with different types of families in (1) and (2); (4) the marker locus is not a disease susceptibility locus; and (5) existence of allelic heterogeneity. We implement this approach in a user-friendly computer program: TDT Power Calculator. Its applications are demonstrated. The approach and the program developed here should be significant for theoreticians to accurately investigate the statistical power of the TDT in various situations, and for empirical geneticists to plan efficient studies using the TDT.

Calcitonin gene-related peptide-mediated ischemic preconditioning in the rat heart: influence of age

In the present study, we examined whether age-related reduction of ischemic preconditioning is related to calcitonin gene-related peptide (CGRP) release in the rat heart. Thirty minutes of global ischemia and 40 min of reperfusion caused a significant decrease of cardiac function and a marked increase of creatine kinase (CK) release at 2, 6 and 20 months of age. Ischemic preconditioning and pretreatment with CGRP for 5 min significantly improved cardiac function and reduced CK release during reperfusion at 2 and 6 months of age but not at 20 months of age. The content of CGRP in the coronary effluent during ischemic preconditioning was significantly increased in the first cycle at 2, 6 months of age but not at 20 months of age. These results suggest that the protection afforded by ischemic preconditioning is decreased in aging hearts, and the age-related change may be related to reduction of the release and effect of CGRP in the rat heart.

Monophosphoryl lipid A-induced delayed preconditioning is mediated by calcitonin gene-related peptide

The delayed preconditioning of the heart by monophosphoryl lipid A is mediated by endogenous nitric oxide (NO), and the cardioprotection afforded by nitroglycerin is related to stimulation of calcitonin gene-related peptide (CGRP) release. The objective of this study was to explore whether improvement of preservation with cardioplegia by monophosphoryl lipid A is mediated by CGRP. In addition, we examined the effect of monophosphoryl lipid A on the tumor necrosis factor-alpha (TNF-alpha) content of myocardial tissues. The isolated rat heart was perfused in the Langendorff mode. Heart rate, coronary flow, left-ventricular pressure, and its first derivatives (+/-dp/dt(max)) were recorded, and plasma levels of NO and CGRP, the release of creatine kinase in coronary effluent and the content of TNF-alpha in myocardial tissues were measured. Hypothermic ischemia for 4 h caused a decline in cardiac function, and an increase in the release of creatine kinase and in the content of TNF-alpha. Pretreatment with monophosphoryl lipid A (500 microg/kg, i.p.) for 24 h improved the recovery of cardiac function and reduced the release of creatine kinase concomitantly with a decrease in the content of cardiac TNF-alpha. Monophosphoryl lipid A markedly increased plasma concentrations of CGRP and NO. After pretreatment with L-nitroarginine methyl ester (L-NAME), the cardioprotection and the increased release of NO and CGRP induced by monophosphoryl lipid A were abolished. Capsaicin also abolished the cardioprotection and the increased release of CGRP induced by monophosphoryl lipid A, but did not affect the content of NO. The results suggest that monophosphoryl lipid A-induced preconditioning enhances preservation with cardioplegia and that the protective effects of monophosphoryl lipid A are related to stimulation of CGRP release.

LOD score exclusion analyses for candidate genes using random population samples

While extensive analyses have been conducted to test for, no formal analyses have been conducted to test against, the importance of candidate genes with random population samples. We develop a LOD score approach for exclusion analyses of candidate genes with random population samples. Under this approach, specific genetic effects and inheritance models at candidate genes can be analysed and if a LOD score is < or = - 2.0, the locus can be excluded from having an effect larger than that specified. Computer simulations show that, with sample sizes often employed in association studies, this approach has high power to exclude a gene from having moderate genetic effects. In contrast to regular association analyses, population admixture will not affect the robustness of our analyses; in fact, it renders our analyses more conservative and thus any significant exclusion result is robust. Our exclusion analysis complements association analysis for candidate genes in random population samples and is parallel to the exclusion mapping analyses that may be conducted in linkage analyses with pedigrees or relative pairs. The usefulness of the approach is demonstrated by an application to test the importance of vitamin D receptor and estrogen receptor genes underlying the differential risk to osteoporotic fractures.

Role of calcitonin gene-related peptide in ischaemic preconditioning in diabetic rat hearts

1. It has been suggested that calcitonin gene-related peptide (CGRP) is involved in the protection provided by ischaemic preconditioning in rat hearts and that ischaemic preconditioning is absent in diabetic rat hearts. 2. In the present study, we tested the relationship between sensory nerve function and ischaemic preconditioning in diabetic rats. 3. In 4- and 8-week diabetic rats and age-matched non- diabetic controls, 30 min global ischaemia and 40 min reperfusion caused a significant decrease in cardiac function and a marked increase in creatine kinase (CK) release. Ischaemic preconditioning, by three cycles of 5 min ischaemia and 5 min reperfusion, improved the recovery of cardiac function and decreased CK release during reperfusion in 4-week diabetic rat hearts. However, the cardioprotection afforded by ischaemic preconditioning was lost in 8-week diabetic rat hearts. Pretreatment with CGRP for 5 min also significantly improved the recovery of cardiac function and decreased CK release in rats subjected to 4 or 8 weeks of diabetes. 4. The content of CGRP in the coronary effluent during ischaemic preconditioning was significantly increased in 4-week diabetic rat hearts (P < 0.05). However, only a slight increase in the release of CGRP was shown in 8-week diabetic rat hearts (P > 0.05). 5. In summary, the present results suggest that the protection afforded by ischaemic preconditioning is attenuated in diabetic rats and that the change may be related to the reduction in CGRP release in diabetic rat hearts.

On the mechanism of the protective effects of nitroglycerin and nicorandil in cardiac anaphylaxis

Previous investigations have shown that nitric oxide donors and nicorandil can suppress allergic reaction. In the present study, the protective effects of nitroglycerin and nicorandil on cardiac anaphylaxis were examined. Presensitized guinea-pig hearts challenged with specific antigen caused a marked decrease in coronary flow (CF), left ventricular pressure (LVP) and its derivatives (+/-dp/dtmax), increase in heart rate, and prolongation of P-R interval. Nitroglycerin (300 nM) or nicorandil (100 microM) markedly increased the content of calcitonin gene-related peptide (CGRP) concomitant with a significant improvement of the cardiac dysfunction and alleviation of the extension of P-R interval. Nicorandil at a concentration of 100 microM also inhibited the sinus tachycardia and histamine release. The protection afforded by nitroglycerin was abolished by glibenclamide, a blocker of ATP-sensitive potassium channels, or by CGRP8-37, the selective CGRP receptor antagonist, or by pretreatment with capsaicin, which depletes endogenous CGRP. The inhibitory effect of nicorandil on cardiac anaphylaxis was abolished only by glibenclamide but not by pretreatment with capsaicin. These results suggest that nitroglycerin and nicorandil possess a protection of cardiac anaphylactic injury. The present study also suggests that the protective effect of nitroglycerin may be related to stimulation of CGRP release and opening the KATP channel, and that the effect of nicorandil is mainly due to the activation of the KATP channel.

An amplified fragment length polymorphism map of the silkworm

The silkworm (Bombyx mori L.) is a lepidopteran insect with a long history of significant agricultural value. We have constructed the first amplified fragment length polymorphism (AFLP) genetic linkage map of the silkworm B. mori at a LOD score of 2.5. The mapping AFLP markers were genotyped in 47 progeny from a backcross population of the cross no. 782 x od100. A total of 1248 (60.7%) polymorphic AFLP markers were detected with 35 PstI/TaqI primer combinations. Each of the primer combinations generated an average of 35.7 polymorphic AFLP markers. A total of 545 (44%) polymorphic markers are consistent with the expected segregation ratio of 1:1 at the significance level of P = 0.05. Of the 545 polymorphic markers, 356 were assigned to 30 linkage groups. The number of markers on linkage groups ranged from 4 to 36. There were 21 major linkage groups with 7-36 markers and 9 relatively small linkage groups with 4-6 markers. The 30 linkage groups varied in length from 37.4 to 691.0 cM. The total length of this AFLP linkage map was 6512 cM. Genetic distances between two neighboring markers on the same linkage group ranged from 0.2 to 47 cM with an average of 18.2 cM. The sex-linked gene od was located between the markers P1T3B40 and P3T3B27 at the end of group 3, indicating that AFLP linkage group 3 was the Z (sex) chromosome. This work provides an essential basic map for constructing a denser linkage map and for mapping genes underlying agronomically important traits in the silkworm B. mori L.

Population admixture: detection by Hardy-Weinberg test and its quantitative effects on linkage-disequilibrium methods for localizing genes underlying complex traits

In association studies searching for genes underlying complex traits, the results are often inconsistent, and population admixture has been recognized qualitatively as one major potential cause. Hardy-Weinberg equilibrium (HWE) is often employed to test for population admixture; however, its power is generally unknown. Through analytical and simulation approaches, we quantify the power of the HWE test for population admixture and the effects of population admixture on increasing the type I error rate of association studies under various scenarios of population differentiation and admixture. We found that (1) the power of the HWE test for detecting population admixture is usually small; (2) population admixture seriously elevates type I error rate for detecting genes underlying complex traits, the extent of which depends on the degrees of population differentiation and admixture; (3) HWE testing for population admixture should be performed with random samples or only with controls at the candidate genes, or the test can be performed for combined samples of cases and controls at marker loci that are not linked to the disease; (4) testing HWE for population admixture generally reduces false positive association findings of genes underlying complex traits but the effect is small; and (5) with population admixture, a linkage disequilibrium method that employs cases only is more robust and yields many fewer false positive findings than conventional case-control analyses. Therefore, unless random samples are carefully selected from one homogeneous population, admixture is always a legitimate concern for positive findings in association studies except for the analyses that deliberately control population admixture.

Involvement of calcitonin gene-related peptide in nitroglycerin induced improvement of preservation with cardioplegic solution

AIM

To study improvement of preservation with cardioplegic solution induced by nitroglycerin was related to stimulation of calcitonin gene-related peptide (CG RP) release.

METHODS

The isolated rat heart was arrested using St Thomas Hospital cardioplegic solution and then was reperfused with normothermic Krebs-Henseleit solution for 40 min after the 4-h hypothermic ischemic period. Hear t rate, coronary flow, left ventricular pressure (LVP), and its first derivative (+/- dp/dtmax) were recorded, and the calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and the release of creatine kinase (CK) were measured.

RESULTS

Nitroglycerin (0.1 or 1 micro;mol/L) or CGRP (5 or 10 nmol/L) caused an improvement of cardiac function (LVP and +/- dp/dtmax) and a decrease in the release of creatine kinase during reperfusion. The protection induced by nitroglycerin was abolished by CGRP(8-37), the selective CGRP receptor antagonist, or pretreatment wit h capsaicin to deplete sensory nerves neurotransmitter content, but was unaltered by treatment w ith glibenclamide, the blocker of the ATP-sensitive potassium channel (KATP). The protection induced by exogenous CGRP was not also blocked by glibenclamide. Levels of CGRP-LI in the coronary effluent were significantly increased in the hearts treated with nitroglycerin. However, the elevated level of CGRP-LI by nitroglycerin was abolished by pretreatment with capsaicin.

CONCLUSION

The improvement of preservation with cardioplegic solution induced by nitroglycerin was related to stimulation of CGRP release in the rat heart, and the effect is not related to the activation of the KATP channel.

Characterization of genetic and lifestyle factors for determining variation in body mass index, fat mass, percentage of fat mass, and lean mass

In this study, we simultaneously characterized genetic and lifestyle factors (exercise, smoking, and alcohol consumption) in determining variation in body mass index (BMI), fat mass, percentage of fat mass (PFM), and lean mass while adjusting for the effects of age and sex. Six hundred fifty-eight Caucasian individuals from 48 pedigrees were studied for BMI. Among these individuals, 289 from 38 pedigrees were studied for fat mass, PFM, and lean mass measured by dual X-ray absorptiometry (DXA). After adjusting for age, sex, and lifestyle factors, the heritabilities (h(2)) of BMI, fat mass, PFM, and lean mass ranged from 0.52 to 0.57 with associated standard errors ranging from 0.09 to 0.14. After accounting for significant sex and age effects, exercise had significant effects for all the phenotypes studied, and the effects of smoking and alcohol consumption were not significant. Therefore, significant proportions of variation in BMI, fat mass, PFM, and lean mass were under genetic control, and exercise had a significant effect in reducing BMI, fat mass, and PFM and in increasing lean mass. This study warrants further genetic linkage analyses to search for genes for the obesity-related phenotypes measured by DXA in our population.

Role of calcitonin gene-related peptide in prostaglandins-mediated ischemic preconditioning in guinea pig hearts

AIM

To examine the role of calcitonin gene-related peptide (CGRP) in ischemic preconditioning induced by prostaglandins in isolated guinea pig hearts.

METHODS

The isolated guinea pig hearts were perfused in a Langendorff model. The heart rate, coronary flow, left ventricular pressure, and its first derivatives (+/-dp/dt(max)) were recorded and the calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and 6-keto-PGF(1 alpha) were measured.

RESULTS

Endothelin-1 (200 pmol in 1 mL K-H buffer) reduced the left ventricular developed pressure and its first derivatives (+/-dp/dt(max)), heart rate, and coronary flow. Preconditioning with two cycles of 5-min global ischemia and 5-min reperfusion attenuated endothelin-1 induced myocardial injury, and concentrations of both CGRP and 6-keto-PGF(1alpha) in the coronary effluent were markedly raised in the preconditioning periods. Pretreatment with capsaicin, which depletes endogenous CGRP, abolished the elevated level of CGRP concomitantly with loss of the cardioprotection induced by ischemic preconditioning. CGRP(8-37) (100 nmol/L), a selective CGRP1 receptor antagonist, also abolished the protective effects of ischemic preconditioning. After pretreatment with indometacin (10 micromol/L), an inhibitor of cyclooxygenase, the protective effects of ischemic preconditioning were abolished and the release of 6-keto-PGF1alpha was no longer elevated. Pretreatment with indometacin abolished the elevated level of CGRP in the coronary effluent.

CONCLUSION

Endogenous prostaglandins are involved in the protective effects of ischemic preconditioning, and the beneficial effects of prostaglandins are mediated by CGRP in the guinea pig heart.

Inhibition of cardiac tumor necrosis factor-alpha production by calcitonin gene-related peptide-mediated ischemic preconditioning in isolated rat hearts

Previous investigations have demonstrated that calcitonin gene-related peptide (CGRP) plays an important role in the mediation of ischemic preconditioning in rats. In the present study, we examined signal transduction pathways of CGRP-mediated ischemic preconditioning. Thirty minutes of global ischemia and 40 min of reperfusion caused a dramatic decrease in myocardial function, and a significant increase in the release of cardiac creatine kinase in the coronary effluent and in the content of tumor necrosis factor-alpha (TNF-alpha) in myocardial tissues. However, ischemic preconditioning (three cycles of 5-min ischemia and 5-min reperfusion) or pretreatment with CGRP for 5 min dramatically improved the recovery of cardiac function, and reduced the release of cardiac creatine kinase and the TNF-alpha content. The effect of ischemic preconditioning was abolished by CGRP-(8-37), the selective CGRP receptor antagonist, and by capsaicin, which depletes sensory nerve neurotransmitter content, but was unaltered by treatment with glibenclamide, a blocker of the ATP-sensitive potassium (K(ATP)) channel. The protective effects of exogenous CGRP-induced preconditioning were also not blocked by glibenclamide. These results suggest that the cardioprotective effects afforded by CGRP-mediated ischemic preconditioning are related to inhibition of cardiac TNF-alpha production, but not to activation of the K(ATP) channel.

Determination of bone mineral density of the hip and spine in human pedigrees by genetic and life-style factors

In 40 human pedigrees with 563 subjects, we evaluated the contribution of genetic and life-style factors (exercise, smoking, and alcohol consumption) and the interactions between non-genetic factors in determining bone mineral density (BMD) of the hip and spine. In our analysis, we adjusted for age, weight, height, menopausal status in females, life-style factors, and the significant interactions among these factors. For the spine and hip BMD, heritabilities (h(2)) (+/- SE) were, respectively, 0.68 (0.21) and 0.86 (0.28) in males and 0.64 (0.13) and 0.67 (0.14) in females. Exercise had significant beneficial effects for male spine BMD and female hip BMD. Alcohol consumption experienced in our sample had significant beneficial effects on hip BMD in both sexes. Although the main effect of smoking was not significant, there were significant interaction effects between smoking and other important factors (e.g., exercise, weight, alcohol consumption). For example, for female spine BMD, exercise had significant beneficial effects in smokers; however, its effect in non-smokers was non-significant. This result indicates that exercise may reduce deleterious effects of smoking (if any) on BMD, but may have minor effects in increasing BMD in non-smokers. The various interaction effects among risk factors explicitly revealed here for the first time indicate that the detailed effects and direction of individual risk factors may depend on the presence and magnitude of other factors. Weight invariably affected BMD of the hip and spine in both sexes. Age effects were significant for hip BMD, but not for male spine BMD.

Fragment size difference between multiplex and singleplex PCR products and their practical implications

By simultaneously amplifying several loci in the same reaction, multiplex PCR has been used in gene mapping and DNA typing with polymorphic short tandem repeat loci. Previous studies have discussed in detail the various parameters and conditions that influence the quantity of individual products generated by multiplex PCR. In practice, when a primer pair fails to amplify in a multiplex PCR for some individuals, singleplex PCR is often employed as a supplement to amplify the primer pair. However, the reliability of this procedure is unknown. In this study, we used six primer pairs from ABI PRISM Linkage Mapping Set version 2 to perform multiplex and singleplex reactions. The fluorescence-labeled amplification products were separated and detected on ABI PRISM 310 Genetic Analyzer. We found that for the marker D1S468, multiplex and singleplex reactions for the majority of individuals yielded reactions of different sizes. Therefore, the potential size difference between multiplex and singleplex reactions needs to be investigated. This investigation is essential to employ multiplex PCR supplemented with singleplex PCR in gene mapping and DNA typing.

Association of estrogen receptor-alpha genotypes with body mass index in normal healthy postmenopausal Caucasian women

Several lines of evidence suggest the importance of the estrogen receptor (ER) in determining body mass index (BMI). Our purpose was to investigate whether genetic polymorphisms at the restriction enzyme PvuII site of the ER-alpha gene locus are associated with BMI variation. Data on BMI, age, and ER-alpha genotypes were obtained from 108 healthy midwestern U.S. postmenopausal Caucasian women. The study subjects were unrelated and aged 65 yr and over (mean age +/- SD, 73.4 +/- 5.1 yr), with an average BMI of 25.25 (SD, 4.04). The ER-alpha genotypes were obtained by PCR followed by restriction enzyme PvuII digestion. We found that in our study subjects the ER-alpha genotypes are significantly associated with BMI (by ANOVA, P = 0.04), explaining about 6.2% of the BMI variation in our study sample. The allelic effects of this locus on BMI are approximately additive. In our sample, individuals of the PP and Pp genotypes have, respectively, 11.4% and 4.8% higher BMI than individuals of the pp genotype. There is a significant ER-alpha genotype by age interaction, so that in our sample PP individuals tend to gain weight with age, whereas Pp and pp individuals tend to lose weight with age. Therefore, the ER-alpha polymorphisms are associated with BMI variation in healthy postmenopausal Caucasian women aged 65 yr and over. Our result is consistent with some recent findings suggesting the potential effects of the ER on BMI. The importance of the ER-alpha genotypes in other populations and other age groups needs to be demonstrated. Although the results of the ER-alpha genotype by age interaction are obtained here from cross-sectional data, direct confirmation may come from longitudinal studies in which individuals are measured multiple times over several years. The importance of the ER-alpha genotypes on BMI should be confirmed by further studies using methods robust to the potential problem of population substructuring that may confound the conclusions of population association studies.

Genetic determination of Colles' fracture and differential bone mass in women with and without Colles' fracture

Osteoporotic fractures (OFs) are a major public health problem. Direct evidence of the importance and, particularly, the magnitude of genetic determination of OF per se is essentially nonexistent. Colles' fractures (CFs) are a common type of OF. In a metropolitan white female population in the midwestern United States, we found significant genetic determination of CF. The prevalence (K) of CF is, respectively, 11.8% (+/- SE 0.7%) in 2471 proband women aged 65.55 years (0.21), 4.4% (0.3%) in 3803 sisters of the probands, and 14.6% (0.7%) in their mothers. The recurrence risk (K0), the probability that a woman will suffer CF if her mother has suffered CF is 0.155 (0.017). The recurrence risk (Ks), the probability that a sister of a proband woman will suffer CF given that her proband sister has suffered CF is 0.084 (0.012). The relative risk lambda (the ratio of the recurrence risk to K), which measures the degree of genetic determination of complex diseases such as CF, is 1.312 (0.145; lambda 0) for a woman with an affected mother and 1.885 (0.276; lambda s) for a woman with an affected sister. A lambda-value significantly greater than 1.0 indicates genetic determination of CF. The terms lambda 0 and lambda s are related to the genetic variances of CF. These parameters translate into a significant and moderately high heritability (0.254 [0.118]) for CF. These parameters were estimated by a maximum likelihood method that we developed, which provides a general tool for characterizing genetic determination of complex diseases. In addition, we found that women without CF had significantly higher bone mass (adjusted for important covariates such as age, weight, etc.) than women with CF.

Estimation of parameters of deleterious mutations in partial selfing or partial outcrossing populations and in nonequilibrium populations

The Deng-Lynch method was developed to estimate the rate and effects of deleterious genomic mutations (DGM) in natural populations under the assumption that populations are either completely outcrossing or completely selfing and that populations are at mutation-selection (M-S) balance. However, in many plant and animal populations, selfing or outcrossing is often incomplete in that a proportion of populations undergo inbreeding while the rest are outcrossing. In addition, the degrees of deviation of populations from M-S balance are often not known. Through computer simulations, we investigated the robustness and the applicability of the Deng-Lynch method under different degrees of partial selfing or partial outcrossing and for nonequilibrium populations approaching M-S balance at different stages. The investigation was implemented under constant, variable, and epistatic mutation effects. We found that, generally, the estimation by the Deng-Lynch method is fairly robust if the selfing rate (S) is <0.10 in outcrossing populations and if S > 0.8 in selfing populations. The estimation may be unbiased under partial selfing with variable and epistatic mutation effects in predominantly outcrossing populations. The estimation is fairly robust in nonequilibrium populations at different stages approaching M-S balance. The dynamics of populations approaching M-S balance under various parameters are also studied. Under mutation and selection, populations approach balance at a rapid pace. Generally, it takes 400-2000 generations to reach M-S balance even when starting from homogeneous individuals free of DGM. Our investigation here provides a basis for characterizing DGM in partial selfing or outcrossing populations and for nonequilibrium populations.

QTL fine mapping by measuring and testing for Hardy-Weinberg and linkage disequilibrium at a series of linked marker loci in extreme samples of populations

It has recently been demonstrated that fine-scale mapping of a susceptibility locus for a complex disease can be accomplished on the basis of deviations from Hardy-Weinberg (HW) equilibrium at closely linked marker loci among affected individuals. We extend this theory to fine-scale localization of a quantitative-trait locus (QTL) from extreme individuals in populations, by means of HW and linkage-disequilibrium (LD) analyses. QTL mapping and/or linkage analyses can establish a large genomic region ( approximately 30 cM) that contains a QTL. The QTL can be fine mapped by examination of the degree of deviation from HW and LD at a series of closely linked marker loci. The tests can be performed for samples of individuals belonging to either high or low percentiles of the phenotype distribution or for combined samples of these extreme individuals. The statistical properties (the power and the size) of the tests of this fine-mapping approach are investigated and are compared extensively, under various genetic models and parameters for the QTL and marker loci. On the basis of the results, a two-stage procedure that uses extreme samples and different tests (for HW and LD) is suggested for QTL fine mapping. This two-step procedure is economic and powerful and can accurately narrow a genomic region containing a QTL from approximately 30-1 cM, a range that renders physical mapping feasible for identification of the QTL. In addition, the relationship between parameterizations of complex diseases, by means of penetrance, and those of complex quantitative traits, by means of genotypic values, is outlined. This means that many statistical genetic methods developed for searching for susceptibility loci of complex diseases can be directly adopted and/or extended to QTL mapping for quantitative traits.

Protective effects of calcitonin gene-related peptide on guinea-pig cardiac anaphylaxis

Anaphylactic events occurring in cardiac tissues can result in cardiac dysfunction via vasoconstriction and arrhythmias. Calcitonin gene-related peptide (CGRP) is the most potent vasodilator and possesses anti-arrhythmic action. We examined the influence of CGRP on cardiac anaphylaxis in guinea-pigs. In the Langendorff-perfused heart of passively sensitized guinea-pigs, antigen challenge evoked a decrease in coronary flow, left ventricular pressure and its maximum first derivatives (+/-dP/dtmax) and an increased heart rate. Antigen challenge also induced atrioventricular conduction block. Treatment with CGRP (1 or 3 nM) significantly improved the recovery of cardiac function and reduced the incidence and duration of atrioventricular block without influencing the increased heart rate. Pretreatment with capsaicin caused effects similar to those of CGRP and markedly elevated the content of CGRP in coronary effluent. Ischaemic preconditioning, induced by two cycles each of 5 min global ischaemia and 5 min reperfusion, also improved cardiac function and raised the level of CGRP in coronary effluent. The protective effects of ischaemic preconditioning were abolished in the presence of the CGRP receptor antagonist CGRP8-37. Histamine release did not differ significantly during any of the interventions. The findings of the present study indicate that, in guinea-pig hearts, CGRP protects against cardiac anaphylaxis and that the cardioprotection by CGRP is independent of histamine release.

Early and delayed protection by capsaicin against reperfusion injury in rat hearts

AIM

To study early or delayed cardioprotection afforded by pretreatment with capsaicin.

METHODS

The isolated rat heart was perfused in a Langendorff model. Heart rate, coronary flow, left ventricular pressure, and its first derivative (+/- dp/dtmax) were recorded, and the calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and the release of creatine kinase (CK) were measured.

RESULTS

Capsaicin (50 mg.kg-1, s.c.) improved the recovery of cardiac function and decreased the release of CK. CK was (2.12 +/- 0.40) and (0.26 +/- 0.04) u.min-1.g-1(wet wt) for ischemia-reperfusion (I/R) and capsaicin + I/R, respectively (P < 0.05). Capsaicin treatment caused an increase in the concentration of CGRP-LI in plasma. CGRP-LI was (135 +/- 12) and (304 +/- 45) ng.L-1 for vehicle + I/R and capsaicin + I/R, respectively (P < 0.05). After pretreatment with capsaicin to deplete the sensory nerve transmitter content, the cardioprotection and the increased level of CGRP by capsaicin were abolished. A delayed protection was shown in the hearts obtained from the rats pretreated with capsaicin 24 h or 48 h before the experiments.

CONCLUSION

Pretreatment with capsaicin induces the early and delayed cardioprotection, which may be related to stimulation of CGRP release in the rat.

Recovery of mutations of different sizes from a population sample of DNA sequences under variable mutation rates across sites

Mutations may be classified according to their positions of occurrence in the genealogy of the sampled DNA sequences from a population. A mutation is said to be of size i if it has i descendants in the sample. Such classifications for mutations may yield detailed insights into the evolutionary history and properties of the population. Statistical methods based on such classification have been developed and shown to be efficient and powerful. However, the utility of these statistical methods critically depends on reliable and robust recovery of mutations of different sizes. We investigated the distributional changes of mutations of different sizes due to genealogy reconstruction using the unweighted pair-group method with arithmetic mean (UPGMA) and the performance of maximum-parsimony method in inferring mutations of different sizes on a given topology. Genealogy reconstruction by UPGMA was found to change the distribution of mutations of different sizes on constructed topologies. Multiple hits at some nucleotide sites made it difficult to infer mutations of different sizes with the maximum-parsimony method, even when the true topology was designated. These results suggest that while the newly developed statistical methods employing information on mutations of different sites are powerful, they also impose significant new challenges for developing methods to accurately recover mutations of different sizes from population DNA sequence data.

Evidence for calcitonin gene-related peptide-mediated ischemic preconditioning in the rat heart

Previous studies have suggested that calcitonin gene-related peptide (CGRP) may play an important role in the mediation of ischemic preconditioning. In the present study, we examined the release of CGRP during ischemic preconditioning and the effect of preconditioning frequency on this effect in the isolated rat heart. Thirty minutes of global ischemia and 40 min of reperfusion caused a significant cardiac dysfunction and an increase in the release of creatine kinase (CK) during reperfusion. Preconditioning with one, two or three cycles of 5-min ischemia and 5-min reperfusion caused a marked improvement of cardiac function and a decrease in the release of CK, and there was no difference in the degree of improvement among groups. The protective effects of ischemic preconditioning were abolished by the CGRP receptor antagonist CGRP(8-37). A single preconditioning cycle induced a significant increase in the release of CGRP in the coronary effluent. In the hearts treated with two or three preconditioning cycles, the level of CGRP was highest in the first cycle, and was gradually decreased with increasing number of cycles of preconditioning. These results suggest that the protective effects of ischemic preconditioning are mediated by endogenous CGRP in the isolated rat heart.

Early and delayed cardioprotection by heat stress is mediated by calcitonin gene-related peptide

Brief ischaemia or heat stress protects the myocardium against ischaemia-reperfusion injury. Heat stimulus evokes release of sensory nerve transmitters, including calcitonin gene-related peptide (CGRP). Since CGRP has been shown to play an important role in the mediation of ischaemic preconditioning, the present study examined whether early or delayed preconditioning induced by retrograde hyperthermic perfusion in vitro or by whole-body hyperthemia in vivo also involves endogenous CGRP. Isolated rat hearts were perfused in the Langendorff mode and subjected to 30 min global ischaemia and 30 min reperfusion. Heart rate, coronary flow, left ventricular pressure and its first derivatives (+/-dp/dt) were recorded and the CGRP-like immunoreactivity (CGRP-LI) content and the release of creatine kinase (CK) during reperfusion were measured. Retrograde hyperthermic perfusion (42 degrees C) for 5 min improved the recovery of cardiac function, decreased the release of CK and elevated the content of CGRP-LI in the coronary effluent. CGRP(8-37) (10(-7 mol/l), a selective CGRP receptor antagonist, abolished the cardioprotection by heat stress. Pretreatment with capsaicin (50 mg/kg s.c.), which specifically depletes sensory nerve transmitter content, abolished both the cardioprotection and the increased release of CGRP-LI. Whole-body hyperthermia (42 degrees C for 15 min) caused an increase in the plasma concentration of CGRP-LI. Early or delayed protection was shown in the hearts obtained from the animals subjected to whole-body hyperthermia 10 min or 48 h before the experiments. The early or delayed protection by heat stress was also abolished by pretreatment with capsaicin. The present study suggests that, in the rat, the early and delayed cardioprotection induced by heat stress involves endogenous CGRP.