Genetic architecture of prostate cancer in the Ashkenazi Jewish population

Background:

Recently, numerous prostate cancer risk loci have been identified, some of which show association in specific populations. No study has yet investigated whether these single nucleotide polymorphisms (SNPs) are associated with prostate cancer in the Ashkenazi Jewish (AJ) population.

Methods:

A total of 29 known prostate cancer risk SNPs were genotyped in 963 prostate cancer cases and 613 controls of AJ ancestry. These data were combined with data from 1241 additional Ashkenazi controls and tested for association with prostate cancer. Correction for multiple testing was performed using the false discovery rate procedure.

Results:

Ten of twenty-three SNPs that passed quality control procedures were associated with prostate cancer risk at a false discovery rate of 5%. Of these, nine were originally discovered in studies of individuals of European ancestry. Based on power calculations, the number of significant associations observed is not surprising.

Conclusion:

We see no convincing evidence that the genetic architecture of prostate cancer in the AJ population is substantively different from that observed in other populations of European ancestry.

A founder BRCA2 mutation in non-Afrikaner breast cancer patients of the Western Cape of South Africa

Founder mutations in BRCA1 and BRCA2 have been reported in many different populations. We studied 105 Coloured and 16 Black Xhosa women residing in the Western Cape of South Africa diagnosed with breast cancer. We screened these patients using our standard panel of six previously reported SA Afrikaner and Ashkenazi Jewish BRCA1/2 mutations and identified only two Afrikaner mutations. Further screening by the protein truncation test (BRCA1 exon 11, and BRCA2 exons 10 and 11) revealed an additional four deleterious mutations (BRCA1 c.1504_ 1508del,p.Leu502AlafsX2, BRCA2 c.2826_2829del,p.Ile943LysfsX16, c.6447_6448dup,p.Lys2150IlefsX19 and c.5771_5774del,p.Ile1924Argfs X38). The latter, also known in Breast Cancer Information Core nomenclature as 5999del4, was identified in 4 of 105 (3.8%) Coloureds and 4 of 16 (25%) Xhosa women, which makes it a frequent founder mutation in the Western Cape Province. Although this mutation was previously reported to occur in the Netherlands, haplotype analysis indicated two distinct origins for the Dutch and South African mutations, excluding the possibility of a common Dutch ancestor and suggesting gene flow from the indigenous tribes such as the Xhosa to the Coloured population instead. Further studies to determine the carrier rate of this variant in the Xhosa and other SA populations are warranted.

Angiotensin-converting enzyme gene polymorphism (ACEGP) and cancer cachexia (CC): Is there a link?

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Background: ACEGP greatly influences functional status and is currently the gene most involved in human fitness. The insertion allele (II) (a 287 bp fragment) rather than the deletion allele (DD) for the angiotensin-converting enzyme (ACE) gene is associated with low ACE levels in tissues and enhanced metabolic efficiency, as demonstrated by an improved response to vigorous training in healthy individuals. In addition, lower tissue ACE activity in mice was associated with decreased insulin resistance, greater glucose uptake in the skeletal muscle, and higher glycogen and fat stores. The aim of the study was to gather preliminary data on the potential association between muscle mass and ACEGP in advanced cancer patients (ACP). Methods: Buffy coat serum and plasma was obtained from 55 patients 18 years or older, newly diagnosed with Stage III (inoperable)-IV non-small cell lung cancer and unresectable/ metastatic gastrointestinal cancers seen within the McGill University Health Center. Muscle surface area (MSA-cm2) was calculated from computerized tomography slices at the L3 vertebrae using TOMOVISION SliceOmatic software version 4.3. Muscularity (M-cm2/m2) and lean body mass (LBM-kg) were calculated by extrapolation of image analysis used to quantify lean tissue. Results: ANOVA confirmed significant difference (p<0.001) among MSA (II: 134.04±35.23; ID: 122.37±29.74; DD: 115.22±27.55), M (47.72±8.67; 41.65±9.26; 41.80±9.26), and LBM (43.00±11.21; 39.29±9.46; 37.01±8.77). In a multiple linear regression model, the II allele was associated with higher M (p=0.042) and a trend for higher MSA and LBM (p=0.059) independent of age, gender, diagnosis, and treatment received. Conclusions: Our data suggest ACEGP influences muscle mass in ACP. Further investigations in a larger sample of ACP are underway to determine whether ACEGP is an important predisposing factor to CC-associated muscle wasting.

No significant financial relationships to disclose.

The HNPCC associated MSH2*1906G-->C founder mutation probably originated between 1440 CE and 1715 CE in the Ashkenazi Jewish population

The MSH2*1906G-->C mutation was recently shown to be a rare yet highly penetrant mutation leading to colorectal cancer. The mutation was only found among Ashkenazi Jewish individuals and lies on an extended haplotype that is common in that population. This study determined that the mutation probably arose between 11 and 22 generations ago, during the time when the Ashkenazim were living in eastern Europe.

Germline truncating mutations in both MSH2 and BRCA2 in a single kindred

There has been interest in the literature in the possible existence of a gene that predisposes to both breast cancer (BC) and colorectal cancer (CRC). We describe the detailed characterisation of one kindred, MON1080, with 10 cases of BC or CRC invasive cancer among 26 first-, second- or third-degree relatives. Linkage analysis suggested that a mutation was present in BRCA2. DNA sequencing from III: 22 (diagnosed with lobular BC) identified a BRCA2 exon 3 542G>T (L105X) mutation. Her sister (III: 25) had BC and endometrial cancer and carries the same mutation. Following immunohistochemical and microsatellite instability studies, mutation analysis by protein truncation test, cDNA sequencing and quantitative real-time PCR revealed a deletion of MSH2 exon 8 in III: 25, confirming her as a double heterozygote for truncating mutations in both BRCA2 and MSH2. The exon 8 deletion was identified as a 14.9 kb deletion occurring between two Alu sequences. The breakpoint lies within a sequence of 45 bp that is identical in both Alu sequences. In this large BC/CRC kindred, MON1080, disease-causing truncating mutations are present in both MSH2 and BRCA2. There appeared to be no increased susceptibility to the development of colorectal tumours in BRCA2 mutation carriers or to the development of breast tumours in MSH2 mutation carriers. Additionally, two double heterozygotes did not appear to have a different phenotype than would be expected from the presence of a mutation in each gene alone.

Double primary cancers of the breast and thyroid in women: molecular analysis and genetic implications

Multiple primary cancers are characteristic of hereditary cancer syndromes. A familial association between breast and thyroid cancer has been suggested, but a genetic basis for this association has not yet been established. To determine the extent to which double primary cancers of the breast and thyroid are due to common hereditary factors, we conducted a registry- and hospital-based study in Ontario and Quebec. We obtained family histories of 74 women diagnosed with both cancer of the breast and thyroid before 70 years of age. Cancer histories were obtained for the 533 first- degree relatives of these women. The observed cancer rate in the relatives was compared with the expected number, based on age- standardized Canadian cancer incidence rates, and relative risks were estimated. A total of 87 cancers were observed in the relatives, compared to 93.7 expected cancers, giving a relative risk of 0.9 (95% confidence interval (CI): 0.7-1.1). The risk for breast cancer was 1.1 (95% CI: 0.6-1.7) and the risk for thyroid cancer was 0.7 (95% CI: 0-3.8). Blood samples were collected on 53 patients for mutational analysis of the BRCA1, BRCA2, and PTEN genes. One woman was found to be a carrier of a BRCA1 mutation (exon 11 3227delT). Our findings do not support the hypothesis that a significant proportion of double primary cancers of the breast and thyroid are due to hereditary factors.

Glomeruloid microvascular proliferation is associated with p53 expression, germline BRCA1 mutations and an adverse outcome following breast cancer

Glomeruloid microvascular proliferation (GMP) in breast cancer independently adversely affected survival (relative risk 1.9, 95% CI: 1.2-3.0), particularly among women who received adjuvant chemotherapy (10-year survival 27 vs 69%, P=0.0003), and was significantly associated with p53 overexpression and BRCA1 germline mutations. The presence of GMP may influence treatment decisions.

The founder mutation MSH2*1906G-->C is an important cause of hereditary nonpolyposis colorectal cancer in the Ashkenazi Jewish population

Hereditary nonpolyposis colorectal cancer (HNPCC) is caused by mutations in the mismatch-repair genes. We report here the identification and characterization of a founder mutation in MSH2 in the Ashkenazi Jewish population. We identified a nucleotide substitution, MSH2*1906G-->C, which results in a substitution of proline for alanine at codon 636 in the MSH2 protein. This allele was identified in 15 unrelated Ashkenazi Jewish families with HNPCC, most of which meet the Amsterdam criteria. Genotype analysis of 18 polymorphic loci within and flanking MSH2 suggested a single origin for the mutation. All colorectal cancers tested showed microsatellite instability and absence of MSH2 protein, by immunohistochemical analysis. In an analysis of a population-based incident series of 686 Ashkenazi Jews from Israel who have colorectal cancer, we identified 3 (0.44%) mutation carriers. Persons with a family history of colorectal or endometrial cancer were more likely to carry the mutation than were those without such a family history (P=.042), and those with colorectal cancer who carried the mutation were, on average, younger than affected individuals who did not carry it (P=.033). The mutation was not detected in either 566 unaffected Ashkenazi Jews from Israel or 1,022 control individuals from New York. In hospital-based series, the 1906C allele was identified in 5/463 Ashkenazi Jews with colorectal cancer, in 2/197 with endometrial cancer, and in 0/83 with ovarian cancer. When families identified by family history and in case series are included, 25 apparently unrelated Ashkenazi Jewish families have been found to harbor this mutation. Although this pathogenic mutation is not frequent in the Ashkenazi Jewish population (accounting for 2%-3% of colorectal cancer in those whose age at diagnosis is <60 years), it is highly penetrant and accounts for approximately one-third of HNPCC in Ashkenazi Jewish families that fulfill the Amsterdam criteria.

Haplotype analysis of a BRCA1: 185delAG mutation in a Chilean family supports its Ashkenazi origins

At least 25% of Ashkenazi Jewish families with two or more cases of premenopausal breast cancers are attributable to one of three founder mutations in BRCA1 or BRCA2. As these three founder mutations are common in the Ashkenazi Jewish population ( approximately 2.5%) and can easily be tested for in a multiplex assay, establishing ethnicity can expedite genetic testing. It is not always possible, however, to conclusively establish ethnicity before offering testing. We report here the occurrence of a founder Ashkenazi Jewish BRCA1 mutation, 185delAG (also known as 187delAG), in a non-Jewish Chilean family with no reported Jewish ancestry. The linked haplotype present in this family was identical to that identified in the Ashkenazi Jewish population. This case report not only illustrates the problem of the definition of ethnicity but also points to the possibility of further studies of the frequency of founder Ashkenazi Jewish mutations in populations not generally considered to be of Ashkenazi Jewish origin.

An MLH1 haplotype is over-represented on chromosomes carrying an HNPCC predisposing mutation in MLH1

BACKGROUND

The mismatch repair gene, MLH1, appears to occur as two main haplotypes at least in white populations. These are referred to as A and G types with reference to the A/G polymorphism at IVS14-19. On the basis of preliminary experimental data, we hypothesised that deviations from the expected frequency of these two haplotypes could exist in carriers of disease associated MLH1 germline mutations.

METHODS

We assembled a series (n=119) of germline MLH1 mutation carriers in whom phase between the haplotype and the mutation had been conclusively established. Controls, without cancer, were obtained from each contributing centre. Cases and controls were genotyped for the polymorphism in IVS14.

RESULTS

Overall, 66 of 119 MLH1 mutations occurred on a G haplotype (55.5%), compared with 315 G haplotypes on 804 control chromosomes (39.2%, p=0.001). The odds ratio (OR) of a mutation occurring on a G rather than an A haplotype was 1.93 (95% CI 1.29 to 2.91). When we compared the haplotype frequencies in mutation bearing chromosomes carried by people of different nationalities with those seen in pooled controls, all groups showed a ratio of A/G haplotypes that was skewed towards G, except the Dutch group. On further analysis of the type of each mutation, it was notable that, compared with control frequencies, deletion and substitution mutations were preferentially represented on the G haplotype (p=0.003 and 0.005, respectively).

CONCLUSION

We have found that disease associated mutations in MLH1 appear to occur more often on one of only two known ancient haplotypes. The underlying reason for this observation is obscure, but it is tempting to suggest a possible role of either distant regulatory sequences or of chromatin structure influencing access to DNA sequence. Alternatively, differential behaviour of otherwise similar haplotypes should be considered as prime areas for further study.

A link between diabetes and atherosclerosis: Glucose regulates expression of CD36 at the level of translation

Both the risk and the rate of development of atherosclerosis are increased in diabetics, but the mechanisms involved are unknown. Here we report a glucose-mediated increase in CD36 mRNA translation efficiency that results in increased expression of the macrophage scavenger receptor CD36. Expression of CD36 was increased in endarterectomy lesions from patients with a history of hyperglycemia. Macrophages that were differentiated from human peripheral blood monocytes in the presence of high glucose concentrations showed increased expression of cell-surface CD36 secondary to an increase in translational efficiency of CD36 mRNA. We obtained similar data from primary cells isolated from human vascular lesions, and we found that glucose sensitivity is a function of ribosomal reinitiation following translation of an upstream open reading frame (uORF). Increased translation of macrophage CD36 transcript under high glucose conditions provides a mechanism for accelerated atherosclerosis in diabetics.

Prevalence of founder BRCA1 and BRCA2 mutations in unselected French Canadian women with breast cancer

The frequency of BRCA1 and BRCA2 mutations in women with breast cancer varies according to the age at diagnosis, family history of cancer, and ethnicity/country of origin. We set out to estimate the frequency of seven previously described founder mutations in BRCA1 and BRCA2 in all eligible French Canadian women diagnosed with invasive breast cancer at one Montreal hospital over a 20-month period. One hundred and ninety-two patients were eligible and 127 (66.2%) provided blood for genetic testing. We identified 4 women who carried a founder mutation (3.1%, 95% confidence interval 0.9-7.9%) in this population. Interestingly, all the mutations were in BRCA2. The mean age at diagnosis for mutation carriers was 51.2 years (range 49.1-53.5). Two of these 4 cases were lobular invasive carcinomas and 2 were ductal carcinomas, histological grade 1 or 2. Despite a small tumor size (< or =20 mm), axillary nodal involvement was present in 3 women. Estrogen receptors were strongly expressed in all cases. Two of the 4 cases reported a strong family history of breast cancer, but a family history of site-specific breast cancer was a relatively poor indicator of the presence of BRCA2 mutations. The absence of BRCA1 mutations may be a result of chance, but may also reflect different geographical origins of the most common BRCA1 mutations within the French Canadian population.

TP53 mutations in breast cancer associated with BRCA1 or BRCA2 germ-line mutations: distinctive spectrum and structural distribution

Several groups have studied the molecular pathology of inherited breast cancer. By combining several such studies, we show in this study that somatic TP53 abnormalities are more common in breast cancer associated with BRCA1 or BRCA2 germ-line mutations than in sporadic breast cancers (odds ratio, 2.8; P = 0.0003). Then, we compared the spectrum of TP53 mutations for breast cancers in the IARC TP53 mutation database with the 82 mutations reported in BRCA1/2-associated breast cancers. The spectrum differed significantly both in distribution (P < 1 x 10(-6)) and in base changes (P = 0.025). Mutations at A:T bp were more common in BRCA1/2-associated tumors and strand bias suggesting DNA repair abnormalities was found. Changes were common at TP53 codons that are not mutation hotspots. Structural modeling showed that most of these p53 non-hotspot amino acids characterized in breast tumors isolated from patients with deficient BRCA1/2 function are distributed in a region of the protein on the opposite side of the p53 DNA-binding surface. Our results suggest that BRCA1/2 mutations influence the type and distribution of TP53 mutations seen in breast cancer.

Polymorphisms in GSTM1, GSTT1 and CYP1A1 and risk of pancreatic adenocarcinoma

A prospective study of 149 unselected incident cases of pancreatic adenocarcinoma and 146 ethnically-matched controls found no associations between GSTM1 (adjusted odds ratio (AOR) 1.14), GSTT1 (AOR: 1.19) and CYP1A1 (AOR: 1.08) polymorphisms and pancreatic cancer susceptibility. Smoking and drinking status did not affect results. These polymorphisms do not appear to be important gene modifiers in pancreatic cancer.

No association between P53 codon 72 polymorphism and risk of squamous cell carcinoma of the head and neck

An initial report suggested that patients homozygous for the arginine allele at codon 72 of P53 were at increased risk for human papillomavirus (HPV)-related cervical cancer, but other groups have not confirmed this finding. Since approximately 18-36% of head and neck cancers are HPV-related, we examined the genotypic frequencies at that locus in 163 cases with squamous cell carcinoma of the head and neck (SCCHN) and 163 ethnically matched controls. We found no significant excess of arginine homozygotes in cases compared to controls (P= 0.50). No significant differences in allele frequencies were observed when the data were stratified by tobacco exposure or by cancer site. These findings suggest a limited role, if any, for this P53 polymorphism in SCCHN.

Prevalence and penetrance of BRCA1 and BRCA2 gene mutations in unselected Ashkenazi Jewish women with breast cancer

BACKGROUND

Approximately 2.0%-2.5% of Ashkenazi Jewish women carry one of three founding mutations in the BRCA1 and BRCA2 genes, and each mutation is associated with a high lifetime risk of invasive breast cancer. We investigated the extent to which these three mutations contribute to breast cancer incidence in the Ashkenazi Jewish population.

METHODS

We ascertained 457 Jewish women with prevalent cases of breast cancer who were unselected for age or family history of the disease; 412 of these women were tested for the three founder mutations (case patients). Control subjects consisted of 360 non-Jewish women with breast cancer (control patients) and 380 healthy Jewish women with no history of cancer (control subjects).

RESULTS

Mutations were found in 48 (11.7%) of 412 Jewish case patients. Forty-six of 48 mutations occurred in women with early-onset breast cancer (<50 years) or a history of ovarian or early-onset breast cancer in a first-, second-, or third-degree relative. The estimated penetrance to age 70 years for breast cancer was 59.9% for the BRCA1 gene mutations and 28.3% for the BRCA2 gene mutation. Compared with Jewish control subjects, the relative risk (RR) of breast cancer for first-degree relatives of mutation carriers was 5.16 (95% confidence interval [CI] = 3.14-8. 48), but risk was also increased for relatives of noncarriers (RR = 1.66; 95% CI = 1.18-2.33). The RR of prostate cancer for first-degree relatives of Jewish case patients was 3.36 (95% CI = 1. 49-7.56).

CONCLUSIONS

Approximately 12% of breast cancers in the Ashkenazi Jewish population are attributable to mutations in the BRCA1 or BRCA2 gene. Genetic testing may be useful when Jewish women with breast cancer are diagnosed before age 50 years or have a close relative with ovarian or early-onset breast cancer. An association between breast and prostate cancers was observed in our study population.

Nuclear genes associated with a single Brassica CMS restorer locus influence transcripts of three different mitochondrial gene regions

Previous studies have shown that the mitochondrial orf224/atp6 gene region is correlated with the Polima (pol) cytoplasmic male sterility (CMS) of Brassica napus. We now extend this correlation by showing that the effects of nuclear fertility restoration on orf224/atp6 transcripts cosegregate with the pol restorer gene Rfp1 in genetic crosses. We also show, however, that the recessive rfp1 allele, or a very tightly linked gene, acts as a dominant gene, designated Mmt (modifier of mitochondrial transcripts), in controlling the presence of additional smaller transcripts of the nad4 gene and a gene possibly involved in cytochrome c biogenesis. A common sequence, TTGTGG, maps immediately downstream of the 5' termini of both of the transcripts specific to plants with the Mmt gene and may serve as a recognition motif in generation of these transcripts. A similar sequence, TTGTTG, that may be recognized by the product of the alternate allele (or haplotype), Rfp1, is found within orf224 just downstream of the major 5' transcript terminus specific to fertility restored plants. Our results suggest that Rfp1/ Mmt is a novel nuclear genetic locus that affects the expression of multiple mitochondrial gene regions, with different alleles or haplotypes exerting specific effects on different mitochondrial genes.

Circulating progenitor cells in human ontogenesis: response to growth factors and replating potential

We have measured the number of progenitor cells circulating in fetal (17-32 weeks of gestation), perinatal (36 weeks of gestation), and adult (30-50 years old) blood. The progenitor cells at each ontogenetic stage were also characterized in terms both of the minimal combinations of growth factors they required to form maximal numbers of colonies in vitro and of their self-replication potential, as measured by the number of secondary and tertiary progenitor cells each could generate. The number of progenitor cells circulating in fetal and perinatal blood can be measured by directly plating the unfractionated blood. In this assay, fetal blood contains half the number of progenitor cells detected in perinatal blood (18.0 +/- 16.4 versus 40.88 +/- 0.63, p < 0.01), and the number of progenitor cells in adult blood is below the level of detection of the assay (< 1/8 microliter of blood). To compare the number of progenitor cells in all three stages of human development, progenitor cell counts were performed on blood mononuclear cells enriched by density separation. In this case, the light density cell fractions from fetal and neonatal blood contained the same number of progenitor cells (300/10(5) cells), numbers that were 10-fold higher than those observed with adult blood (30/10(5) cells). Circulating fetal-neonatal erythroid and multipotential progenitor cells were found to differ from their adult counterparts in terms of their response to growth factors and their self-renewal ability. In fact, the number of cytokines required to observe maximal colony formation increased with the ontogenetic stage of the cells. No differences were found in the frequency of primary colonies containing progenitor cells or in the mean number of secondary progenitor cells per primary colony in cultures of fetal, neonatal, or adult blood. Differences between the three ontogenetic stages, however, were found with respect to the number of sequential replatings that were possible. In fact, although both secondary granulocyte-macrophage (GM) and mixed-cell colonies derived from fetal cells gave rise to tertiary colonies, only perinatal secondary mixed-cell colonies grew in tertiary cultures, and no growth was observed in tertiary cultures of adult cells. These results suggest that the greater amplification of progenitor cells observed in liquid culture of fetal/neonatal versus adult blood is due both to a higher proliferative capacity of neonatal progenitor cells (up to two replatings versus one) and to a higher frequency in these samples of mixed-cell colony-forming cells (CFC) (37.7 +/- 7.3 versus 2.0 +/- 0.7/10(5) light density cells, respectively). Because of the high numbers of progenitor cells circulating in the fetus, as well as their high proliferative capacity, it is predicted that if blood could be harvested directly in utero, fetal blood would be as good a source of stem cells for transplantation as perinatal placental/cord blood. Circulating fetal stem cells would, therefore, represent an ideal target for gene therapy and in utero autologous transplantation.

Tracer disequilibrium in CO2 compartments during NaH14CO3 infusion

The failure of labeled CO2 to equilibrate between extracellular and intracellular CO2 compartments may influence the accuracy of substrate oxidation measurements during infusion of carbon-labeled tracers because it may generate errors in estimate of fixation of labeled CO2 derived from control experiments in which labeled bicarbonate is infused. In this study, normal volunteers received a 14-hour overnight primed continuous infusion of NaH14CO3. Over the last 4 hours of the study, steady-state conditions were achieved in the specific activities (SAs) of expired 14CO2 and plasma urea, which was used as a probe for hepatic intracellular CO2 SA. Plasma urea SA was approximately 17% lower than expired CO2 SA (46.4 +/- 5.6 v 56.8 +/- 3.9 disintegrations per minute.mumol-1, P < .02). Fractional 14CO2 recovery was 94.8% +/- 0.8%; when corrected for failure to equilibrate with intracellular CO2, fractional recovery was 89.5% +/- 1.9%. These data indicate that compartmentalization of CO2 may occur in humans. The duration of our experiments, required because of the long half-life of plasma urea, may have minimized the apparent magnitude of compartmentalization. Furthermore, it is possible that compartmentalization in extrahepatic tissues could be of either lesser or greater magnitude than that which we observed in liver. Whether this phenomenon contributes to incomplete recovery of 14CO2 during NaH14CO3 infusion cannot be determined from our results. Additional studies using different experimental approaches will be required to better measure CO2 compartmentalization.

Increased dietary branched-chain amino acids do not improve growth in developing rats with chronic biliary obstruction

We studied dietary branched-chain amino acid enrichment in cholestatic weanling rats. Growth was assessed with body weight, muscle weight and nitrogen balance. Systemic metabolic measurements that reflect liver function were evaluated, including plasma ammonia, albumin, amino acids, glucose, triglyceride and branched-chain ketoacids, as well as urinary carnitine excretion. Twenty-two rats underwent bile-duct ligation at 14 d of age. At weaning, 11 rats were fed a control diet and 11 an isoenergetic, isonitrogenous branched-chain amino acid-enriched diet for 3 wk, each with a sham-operated, pair-fed control. Body weights were similar in all four groups. Changes due to bile-duct ligation and not affected by the diet manipulation included lower plasma glucose, nitrogen balance and muscle weight, and higher triglyceride concentration, carnitine excretion and liver weight. Changes due to ligation that were normalized by dietary manipulation included plasma albumin, ammonia and total amino acid concentrations. The ratio of branched-chain to aromatic amino acids was decreased in ligated animals fed both diets; however, branched-chain amino acids were lower in the two groups fed more branched-chain amino acids.