CD36 gene polymorphism and plasma sCD36 as the risk factor in higher cholesterolemia

INTRODUCTION

The receptor CD36 has been reported to play an important role in atherogenicity. The aim of this study was to gain insight into the relationship between CD36 gene polymorphisms or the plasma concentration of sCD36 and clinical or biochemical parameters in children.

PATIENTS AND METHODS

The study groups comprised Caucasian children with and without hypercholesterolemia. The alterations in the CD36 gene were detected by DHPLC and the plasma concentrations of sCD36 were measured by ELISA.

RESULTS

The data presented suggest that the IVS4-10A allele of CD36 (rs3211892) is associated with a lower risk of hypercholesterolemia. We observed a negative correlation of the sCD36 concentration with uric acid and insulin concentrations, the HOMA-IR ratio, weight, waist and hip circumference, systolic blood pressure, body mass index, waist-hip ratio and mean arterial pressure ratio, but a positive correlation with HDL cholesterol and ApoA1 concentrations. Female gender was a significant independent predictor of a higher plasma sCD36 concentration.

CONCLUSIONS

The data presented suggest a possible protective effect of a higher sCD36 concentration in relation to metabolic syndrome components.

New EPCAM founder deletion in Polish population

It is well known that founder mutations associated with cancer risk have useful implications for molecular diagnostics. We report the presence of a founder mutation in EPCAM involved in the etiology of Lynch syndrome (LS). The mutation extends nearly 8.7 kb (c.858 + 2478_*4507del) and is shared by 8 Polish families. Family members suffered almost exclusively from colorectal cancer; however, pancreatic and gastric cancers were also apparent. Next to mutations c. 2041G>A in MLH1 gene and c.942+3A>T in MSH2, the deletion mutation encompassing EPCAM is one of the most common causative changes responsible for LS in Poland.

Cumulative effects of genetic markers and the detection of advanced colorectal neoplasias by population screening

Genetic markers associated with colorectal cancer may be used in population screening for the early identification of patients at elevated risk of disease. We genotyped 3059 individuals with no cancer family history for eight markers previously associated with colorectal cancer. After colonoscopy, the genetic profile of cases with advanced colorectal neoplasia (213) was compared with the rest (2846). rs2066847 and rs6983267 were significantly associated with the risk of advanced colorectal neoplasia but with limited effect on their own [odds ratio (OR) 1.59; 95% confidence interval (CI) 1.02-2.41; p = 0.033 and OR 1.45; 95% CI 1.02-2.12; p = 0.044, respectively]. Cumulative effects, in contrast, were associated with high risk: the combination of rs2066847, rs6983267, rs4779584, rs3802842 and rs4939827 minimized the number of markers considered, while maximizing the relative size of the carrier group and the risk associated to it, for example, for at least two cumulated risk markers, OR is 2.57 (95% CI 1.50-4.71; corrected p-value 0.0079) and for three or more, OR is 3.57 (95% CI 1.91-6.96; corrected p-value 0.00074). The identification of cumulative models of - otherwise - low-risk markers could be valuable in defining risk groups, within an otherwise low-risk population (no cancer family history).

The -149C>T SNP within the DeltaDNMT3B gene, is not associated with early disease onset in hereditary non-polyposis colorectal cancer

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominantly inherited syndrome caused by germline mutations in mismatch repair (MMR) genes. HNPCC patients have a lifetime risk of 80% of developing colorectal cancer (CRC); however the likely age of onset is difficult to predict. A single C>T polymorphism located within the promoter region of the DeltaDNMT3B gene has recently been reported to be associated with a significant increase to the risk of early onset CRC. In this study we determined the DeltaDNMT3B genotype in 404 confirmed HNPCC participants (total of 194 CRC cases) from Australia (203) and Poland (201). From the total number of participants there were 194 diagnosed cases of CRC and 210 healthy MMR gene mutation carriers. The study was undertaken to assess whether the reported effect observed in a previous study of 146 HNPCC patients is consistent in a larger separate and unrelated participant cohort. Through the statistical tests of Kaplan-Meier survival analysis and Cox hazard regression models we did not observe any significant association between the DeltaDNMT3B C>T SNP and early onset CRC in HNPCC patients.

Germline MSH2 and MLH1 mutational spectrum including large rearrangements in HNPCC families from Poland (update study)

Germline mutations in the DNA mismatch repair genes MSH2 and MLH1 account for a significant proportion of hereditary non-polyposis colorectal cancer (HNPCC) families. One approach by which development of an efficient DNA-testing procedure can be implemented is to describe the nature and frequency of common mutations in particular ethnic groups. Two hundred and twenty-six patients from families matching the Amsterdam II diagnostic criteria or suspected HNPCC criteria were screened for MSH2 and MLH1 germline mutations. Fifty different pathogenic mutations were found, 25 in MSH2 and 25 in MLH1. Twenty-four of these had not previously been described in other populations. Among our 78 families with MSH2 or MLH1 mutations, 54 (69.2%) were affected by recurrent mutations including 38 found at least twice in our own series. Two of the most frequent alterations were a substitution of A to T at the splice donor site of intron 5 of MSH2 and a missense change (A681T) of MLH1 found in 10 and eight families, respectively. Among large deletions detected by the multiplex ligation-dependent probe amplification assay, exon 9 deletions in the MSH2 gene were found in two families. Our results indicate that a screening protocol specific for the Polish population that is limited to the detection of all reported mutations will result in the identification of the majority of changes present in MLH1 and MSH2 genes in Polish HNPCC kindreds.

NOD2 variants and the risk of malignant melanoma

Both hereditary and environmental factors are important in the aetiology of malignant melanoma. Among the risk factors for malignant melanoma are immunodeficiency and immunosuppression. The recently identified NOD2 gene is involved in the regulation of immune function through activation of the transcription factor nuclear factor-kappaB (NF-kappaB). Three common NOD2 mutations -- 3020insC, G908R and R702W -- have been shown to be associated with chronic inflammatory disease such as Crohn's disease, the 3020insC also with human malignancy colorectal cancer. We examined the frequency of the NOD2 variants in 424 patients with malignant melanoma and 649 controls. The 3020insC mutation was present in 6.9% of unselected cases and 7% of the controls (odds ratio (OR) 1.0; P not significant). The mutation was present in 6.8% of 162 cases diagnosed under the age of 50 and in 7.1% of cases diagnosed after the age of 50. A mutation was present in the index case in 5% of 40 familial melanomas (OR 0.7; P not significant). There were no statistically significant differences between prevalence of G908R and R702W in malignant melanoma patients and controls. In conclusion, the three common NOD2 mutations are not associated with increased risk of development of malignant melanoma.

CHEK2 is a multiorgan cancer susceptibility gene

A single founder allele of the CHEK2 gene has been associated with predisposition to breast and prostate cancer in North America and Europe. The CHEK2 protein participates in the DNA damage response in many cell types and is therefore a good candidate for a multisite cancer susceptibility gene. Three founder alleles are present in Poland. Two of these result in a truncated CHEK2 protein, and the other is a missense substitution of an isoleucine for a threonine. We ascertained the prevalence of each of these alleles in 4,008 cancer cases and 4,000 controls, all from Poland. The majority of the common cancer sites were represented. Positive associations with protein-truncating alleles were seen for cancers of the thyroid (odds ratio [OR] 4.9; P=.0006), breast (OR 2.2; P=.02), and prostate (OR 2.2; P=.04). The missense variant I157T was associated with an increased risk of breast cancer (OR 1.4; P=.02), colon cancer (OR 2.0; P=.001), kidney cancer (OR 2.1; P=.0006), prostate cancer (OR 1.7; P=.002), and thyroid cancer (OR 1.9; P=.04). The range of cancers associated with mutations of the CHEK2 gene may be much greater than previously thought.

Increased risk of breast cancer in relatives of malignant melanoma patients from families with strong cancer familial aggregation

The aim of this study was to evaluate the risk of occurrence of malignancies of different site of origin in patients with malignant melanoma (MM) of the skin and their first-degree relatives from families with cancer familial aggregations with unknown pathogenetic background (CFA). We analysed tumour spectrum and age at diagnosis of malignancies in 51 families with MM/CFA. In addition, we evaluated observed frequency (OF); expected frequency (EF); and relative risk (RR) of occurrence of malignancies in these families. In all cases peripheral blood examination of common Polish founder BRCA1 mutations was performed. In 25 families, we analysed loss of heterozygosity of BRCA1 and BRCA2 genes. We identified two subgroups of cases: 22 MM/CFA families with MM diagnosed before 55 years (< or =55 MM/CFA) and 29 MM/CFA families with MM diagnosed after 55 (>55 MM/CFA). In these families we observed increased proportion of breast cancers: 17.52% in the first subgroup (mean age of diagnosis 48.5) and 12.15% in the second subgroup. The odds ratio for breast tumours occurring before 50 in < or =55 MM/CFA families was 3.71. We also observed increased numbers of liver cancers, CSU and leukaemias. OF and EF analyses revealed increased risk of occurrence of cancers of breast (OF 10.4%, EF 4.5%) and liver (OF 1.9%, EF 0.8%) in women from MM/CFA families, RR for breast tumours was approximately 3.3 in < or =55 MM/CFA families. Molecular examination of MM/CFA families revealed no alterations within the BRCA2 gene and one germline mutation of the BRCA1 gene. In conclusion, it seems to be justified to consider systematic breast surveillance beginning at the age around 35-40 years as an option in women from < or =55 MM/CFA families.

Fhit protein expression in hereditary and sporadic colorectal cancers

The majority of hereditary nonpolyposis colorectal cancer (HNPCC) is caused by mutations in DNA mismatch repair genes, especially in MLH1 and MSH2. Tumours in such patients also show microsatellite instability characteristic for DNA repair defects. The FHIT gene, a candidate tumour suppressor gene located at 3p14.2 has been shown to be involved in carcinogenesis of many human tissues, including digestive tract tissues. In our study, we characterized Fhit protein expression in hereditary and sporadic colorectal cancers (CRC). Our intention was to determine if cancers with mutations in the mismatch repair genes, MSH2 and MLH1, would show more frequent inactivation of the FHIT gene. Sixteen HNPCC and 28 sporadic CRC cases were examined by standard immunohistochemical analyses. Both study groups comprised carefully and selectively chosen cases. We have observed higher frequency of loss or reduction of Fhit protein expression in hereditary CRC than in sporadic cases (44% vs. 25%). Although this difference was not statistically significant (p = 0.17), possibly due to the small number of available tumour specimens, the tendency is interesting. More extensive studies on a larger number of cases should be done in the HNPCC group to confirm statistical significance. Our results suggest that the FHIT gene plays an important role in carcinogenesis of at least one fourth of all colorectal cancers.

Fluorescence in situ detection of human cutaneous melanoma: study of diagnostic parameters of the method

Multicenter study of the diagnostic parameters was conducted by three groups in Poland to determine if in situ fluorescence detection of human cutaneous melanoma based on digital imaging of spectrally resolved autofluorescence can be used as a tool for a preliminary selection of patients at increased risk of the disease. Fluorescence examinations were performed for 7228 pigmented lesions in 4079 subjects. Histopathologic examinations showed 56 cases of melanoma. A sensitivity of fluorescence detection of melanoma was 82.7% in agreement with 82.5% found in earlier work. Using as a reference only the results of histopathologic examinations obtained for 568 cases we found a specificity of 59.9% and a positive predictive value of 17.5% (melanomas versus all pigmented lesions) or 24% (melanomas versus common and dysplastic naevi). The specificity and positive predictive value found in this work are significantly lower than reported earlier but still comparable with those reported for typical screening programs. In conclusion, the fluorescence method of in situ detection of melanoma can be used in screening large populations of patients for a selection of patients who should be examined by specialists.

Comparison of Alu-PCR, microsatelite instability, and immunohistochemical analyses in finding features characteristic for hereditary nonpolyposis colorectal cancer

PURPOSE

To evaluate and compare alterations detected by Alu-PCR, microsatellite instability (MI), and absence of hMLH1 and hMSH2 protein expression measured by immunohistochemical (IHC) analyses as features characteristic of hereditary nonpolyposis colorectal cancer (HNPCC).

METHODS

Alu-PCR, MI, and IHC analyses were performed in two groups of patients: (A) HNPCC diagnosed definitively or with high probability (11 patients); (B) sporadic late-onset colorectal cancers (15 patients).

RESULTS

Quantitative alterations recorded by Alu-PCR were not characteristic for Lynch syndrome, occurring more frequently in sporadic late-onset CRC (73% in group B vs 45% in group A). Qualitative changes (occurrence of additional peaks or shifts) have been found to be associated with HNPCC with odds ratio (OR) 2.4, specificity approximately 70% and sensitivity approximately 55%. Findings in MI and IHC analyses have been recognized as features more characteristic of HNPCC suggesting Lynch syndrome with OR 4.8, specificity approximately 80%, sensitivity approximately 55% (MI) and OR 8.0, specificity approximately 93%, sensitivity approximately 36% (IHC).

CONCLUSION

Molecular techniques allowing identification of patients with a high probability of having HNPCC include IHC and MI analyses. Our results suggest that their replacement by Alu-PCR analysis in diagnosis of HNPCC is not justified.

Optimization of experimental conditions for RNA-based sequencing of MLH1 and MSH2 genes

The most sensitive technique for the detection of germline mutations is exon by exon sequencing of the gene under investigation using genomic DNA as a template for analysis. This approach, however, has cost and sensitivity limitations that can, at least in part, be overcome by RNA-based analysis. Germline mutations of MLH1 and MSH2 are the most frequent cause of the inherited susceptibility to colorectal and other epithelial cancers known as hereditary non-polyposis colorectal cancer (HNPCC). We compared the analysis of the MLH1 and MSH2 genes using mRNA and genomic DNA as starting material from 21 HNPCC patients. All samples were investigated by RT-PCR, sequencing of cDNA and simultaneous sequencing of genomic DNA. The cDNA was generated using specific primers complementary to the ends of MLH1 and MSH2 genes, respectively. Mutations in MLH1 and MSH2 were detected in 11 out of 21 unrelated patients. In 10 out of 11 cases, mutations were detected independently of the type of primers used for reverse transcription (RT). One novel missense mutation (K751R) in MLH1 was detected using this method. One nonsense mutation (E205X) in MSH2 was only detectable when RT was performed using MSH2 gene-specific primers. Shorter PCR products indicative of alternatively spliced transcripts were not observed when MLH1 or MSH2 specific cDNA RT primers were employed to generate template, except in one case where exon skipping was observed for exons 9 and 10. In this report we demonstrate that primers specific for RT of MLH1 and MSH2 are crucial for increasing the sensitivity of cDNA analysis. DNA sequencing using RNA as a basis for template construction may be a valuable and economical alternative to genomic DNA sequencing.

Optimization of experimental conditions for RNA-based sequencing of MLH1 and MSH2 genes

The most sensitive technique for the detection of germline mutations is exon by exon sequencing of the gene under investigation using genomic DNA as a template for analysis. This approach, however, has cost and sensitivity limitations that can, at least in part, be overcome by RNA-based analysis. Germline mutations of MLH1 and MSH2 are the most frequent cause of the inherited susceptibility to colorectal and other epithelial cancers known as hereditary non-polyposis colorectal cancer (HNPCC). We compared the analysis of the MLH1 and MSH2 genes using mRNA and genomic DNA as starting material from 21 HNPCC patients. All samples were investigated by RT-PCR, sequencing of cDNA and simultaneous sequencing of genomic DNA. The cDNA was generated using specific primers complementary to the ends of MLH1 and MSH2 genes, respectively. Mutations in MLH1 and MSH2 were detected in 11 out of 21 unrelated patients. In 10 out of 11 cases, mutations were detected independently of the type of primers used for reverse transcription (RT). One novel missense mutation (K751R) in MLH1 was detected using this method. One nonsense mutation (E205X) in MSH2 was only detectable when RT was performed using MSH2 gene-specific primers. Shorter PCR products indicative of alternatively spliced transcripts were not observed when MLH1 or MSH2 specific cDNA RT primers were employed to generate template, except in one case where exon skipping was observed for exons 9 and 10. In this report we demonstrate that primers specific for RT of MLH1 and MSH2 are crucial for increasing the sensitivity of cDNA analysis. DNA sequencing using RNA as a basis for template construction may be a valuable and economical alternative to genomic DNA sequencing.

Age at diagnosis of cancer as predictor of mutation occurrence in families suspected of HNPCC

Analysis of significance of age at cancer diagnosis as a factor allowing identification of a subgroup of patients with a high frequency of hMSH2 and hMLH1 mutations among families that fulfil suspected HNPCC criteria was performed. DNA from thirty-one unrelated patients affected by colorectal cancer from families matching the above criteria were studied by direct sequencing for occurrence of hMSH2 and hMLH1 gene mutations. Seven unequivocal constitutional mutations were detected: five in the hMLH1 gene and two in the hMSH2 gene. Additionally, one hMLH1 alteration of unknown significance was found. All seven mutations were found in a subgroup of 19 patients with cancer diagnosed before the age of 50 years. In a subgroup of 12 patients with cancer diagnosed at an older age only one case with hMLH1 alteration of unknown significance was detected. Our results indicate that early age at cancer diagnosis seems to be a crucial pedigree factor in discrimination of patients with hMSH2 or hMLH1 mutations among families suspected of HNPCC and matching criteria I of ICG-HNPCC.

Value of pedigree/clinical data, immunohistochemistry and microsatellite instability analyses in reducing the cost of determining hMLH1 and hMSH2 gene mutations in patients with colorectal cancer

The aim of this study was to evaluate the significance of pedigree/clinical data, immunohistochemistry (IHC) and microsatellite instability (MI) analyses in the reduction of costs of constitutional hMLH1 and hMSH2 gene mutation diagnosis in patients with colorectal cancers (CRC). Pedigree/clinical data were evaluated on a series of 168 patients with CRC, including 43 consecutive sporadic late-onset and 25 consecutive, definitive or suspected hereditary non-polyposis colorectal cancer (HNPCC) cases, examined by IHC and MI analyses. In the latter group, 6/25 (24%) constitutional mutations were found. We detected no germline mutations in the sporadic late-onset patients. The lowest costs (880 Euro/mutation detected) were achieved by performing pedigree/clinical data (for exclusion of late-onset sporadic CRC) in conjuction with IHC only. In this model 1/6 (17%) mutations was missed. Additional preselection by IHC and MI analyses before sequencing was required to detect all mutations. In this approach, which seems to be the most effective in the search for hMLH1 and hMSH2 gene mutation, the cost was 1767 euro/mutation detected.

Frequency and nature of germline Rb-1 gene mutations in a series of patients with sporadic unilateral retinoblastoma

Constitutional Rb-1 gene mutations were studied in a series of 17 families with isolated unilateral retinoblastoma patients. Peripheral blood lymphocytes were analysed by karyotyping, Southern blot hybridisation, and 'exon by exon' sequencing. Mutations were detected in 4 (24%) of the investigated probands. All mutations were identified by sequencing. No alteration was detected by Southern blotting or karyotyping. In one of our cases with a R358 stop codon mutation, retinoblastoma was unilateral at the time of diagnosis, but a tumour of the second eye was diagnosed after 35 months of follow-up. After exclusion of this case, the frequency of constitutional mutations in our series was 19% (3 of 16 cases). Alterations in our cases without involvement of the second eye included G-->A substitution in the promoter region 198 bp upstream of the initiating methionine codon; G-->C transversion in the splice donor site at position +1 leading to exon 6 skipping and a 137 bp in-frame deletion, starting 3 bp from the 5' end of exon 15 to 27 bp from the 3' end of exon 16. All alterations were germline de novo abnormalities.

Long polymerase chain reaction in detection of germline deletions in the von Hippel-Lindau tumour suppressor gene

Experimental conditions for detection of germline deletions of the von Hippel-Lindau (VHL) gene by means of long polymerase chain reaction have been established. Primers were designed to analyse the VHL gene in three overlapping fragments: 12.5 kb in length containing promoter and exons 1 and 2; 8.7kb in length containing exons 2 and 3; and 16kb in length containing exons 2 and 3 and the 3' untranslated region. Using the described procedure, it was possible to detect large deletions in four of five cases with such mutations previously detected by Southern blotting and in 5 of 11 unrelated Polish VHL patients in whom constitutional VHL gene mutations were not found by sequencing.

The detection of somatic mutations of thyrotropin receptor gene in fine needle biopsy samples from thyroid nodules

OBJECTIVE

To evaluate the detection possibility of TSH receptor gene mutation within the third cytoplasmic loop and the sixth transmembrane domain in the cytological material obtained by means of fine needle biopsy of autonomous and non-autonomous nodules.

METHODS

The study has been carried out in 16 women with goitre showing no clinical signs of hyperthyroidism. According to the thyroid scintigraphy and serum level of thyrotropin (TSH) the patients were divided into two groups: 1. 6 patients with autonomous nodules; 2. 10 patients with non-autonomous nodules. Genomic DNA has been isolated from the cytological material and the peripheral blood nuclear cells in order to confirm possible somatic character of TSH receptor gene mutations. DNA has been amplified in polymerase chain reaction (PCR) with the use of a specific pair of primers. Purified PCR products have been subjected to further automatic sequencing.

RESULTS

Among 6 autonomous nodules tested one heterozygotic somatic mutation of adenine for cytosine at 1804 nucleotide of TSH receptor gene was detected. This mutation resulted in the change of threonine (codon ACC) at 632 position of TSH receptor protein for proline (codon CCC). Among the non-autonomous nodules one heterozygotic somatic mutation of adenine for cytosine at 1870 nucleotide of receptor TSH gene has been detected. From this mutation followed the change of lysine (codon AAG) at 624 position of the polypeptide chain for glutamine (codon CAG) followed as a consequence.

CONCLUSIONS

We emphasize the validity of fine needle biopsy in the detection of somatic mutations in the TSH receptor gene. For the first time the somatic mutation in the TSH receptor gene in a non-autonomous nodule has been reported.

Polymorphism of GSTM1 gene in patients with colorectal cancer and colonic polyps

The frequency of the GSTM1 gene in patients with nonpolyposis colorectal cancer (CRC) (n = 70) and in subjects with colonic polyps (n = 27) was evaluated and compared with healthy individuals (n = 145). Patients with CRC were divided into the three groups: patients coming from the families with hereditary nonpolyposis colorectal cancer (HNPCC) (n = 17); patients with a high risk of HNPCC who were referred to as suspected of HNPCC (n = 25); patients with sporadic colorectal cancer without clinical features of hereditary tumours (n = 28). A simple polymerase chain reaction (PCR) - based assay to identify GSTM1 nulled and positive (non-nulled) genotype was used. No significant differences in frequency of nulled individuals were observed in both patients with HNPCC and patients suspected of HNPCC as well as in subjects with colonic polyps. The most interesting observation was made in the group of patients with sporadic CRC. Twenty individuals (71.4 %) of the group were GSTM 1 deficient which was significantly different from the control population (p < 0.04). The above data indicate that the absence of the GSTM1 gene is associated with a greater risk of sporadic colorectal cancer. There is an increase in the overall risk of approximately 2.5 as compared with the control population.

Relationship between acetylation polymorphism and risk of atopic diseases

It has been shown that slow acetylation rate may be a factor that influences the development of allergic diseases. The influence of NAT2 genetic polymorphism on the risk of development of atopic diseases was evaluated among the white Polish population of 85 patients with atopy (62 children and 23 parents) and 181 healthy individuals (127 children and 54 adults). The NAT2 alleles (*4, *5, *6, and *7) were identified by polymerase chain reaction-restriction fragment length polymorphism methods with DNA extracted from peripheral blood. A significant predominance of homozygous slow acetylators (85%) among patients with atopic diseases was observed. There were no homozygous fast acetylators within this group of individuals. Comparison of the frequency of slow acetylators between the above group of patients and healthy subjects (54%) showed that the significant predominance of slow acetylators was observed in the first group (P < .001). The risk of development of atopic diseases was 5-fold greater for homozygous slow acetylators (odds ratio, 4.69; 95% confidence interval, 2.33-9.59) compared with healthy subjects. We therefore concluded that slow acetylation genotype may be an important factor of individual susceptibility to atopic diseases.

Age at diagnosis to discriminate those patients for whom constitutional DNA sequencing is appropriate in sporadic unilateral retinoblastoma

RB1 gene constitutional mutations were studied using 'exon-by-exon' sequencing in a series of 17 patients with sporadic unilateral retinoblastomas. Constitutional de novo germline mutations were detected in 4 patients. The age at diagnosis of retinoblastoma in all these cases was lower (mean 10.8 months; range 5-18) than in cases in which constitutional mutations were not found (mean 31.7 months; range 19-42). These results strongly indicate that age at retinoblastoma diagnosis may be a major factor for discriminating patients for whom a search for RB1 gene constitutional mutations could be justifiable in sporadic unilateral retinoblastomas.

Leptin receptor isoforms expressed in human adipose tissue

Leptin and its structural gene, Ob, are exclusively expressed in adipose tissue. Leptin is secreted into the blood and is responsible for fat mass regulation via leptin receptors in the hypothalamus. This has been considered the major role of leptin, but leptin receptor isoforms are expressed not only in the brain but also in most other tissues in humans and rodents: heart, placenta, lung, liver, muscle, kidney, pancreas, spleen, thymus, prostate, testes, ovary, small intestine, and colon. This implicates leptin regulation in other systems apart from fat mass regulation, and leptin action has been demonstrated in human fetal development and reproductive development, liver metabolism, hematopoiesis, and insulin secretion. Four splice variants of the leptin receptor have been identified in humans: the long isoform huOb-R and the shorter isoforms B219.1 to B219.3. It is known that the long isoform has full intracellular signaling capacity, and is responsible for anorectic action in the hypothalamus. The roles of the other isoforms are yet to be elucidated. Here, we report the identification by reverse transcriptase-polymerase chain reaction (RT-PCR) of three leptin receptor isoforms coexpressed in human visceral adipose tissue: the long isoform huOb-R and the short isoforms huB219.1 and huB219.3. The possible roles of these isoforms are discussed.

[Mutation T-->C of nucleotide 2238 in the gene of atrial natriuretic peptide (ANP) precursor and heterogeneity of sodium-sensitive hypertension. Preliminary report]

Atrial natriuretic peptide (ANP) is involved in the pathogenesis of sodium-sensitive hypertension. The loss of Sca I restriction site in the ANP precursor gene abolishes the regular stop codon. The aim of our study was the analysis of the Sca I gene polymorphism in 23 patients with sodium-sensitive hypertension, the molecular characteristic of the mutation and the comparison of the blood pressure values, plasma renin activity, plasma ANP and aldosterone concentration between patients with or without mutation. Applying the polymerase chain reaction (PCR), followed by digestion with Sca I, the heterozygous mutation has been found in 9 (39%) patients. The sequencing of PCR products indicated that the loss of Sca I restriction site is caused by T2238-->C transition leading to the translation of ANP with two additional arginines. The higher concentration of ANP in plasma has been found in T2238-->C transition patients on normal and high sodium diet as compared with patients without mutation. These preliminary results suggest that the heterogeneity of sodium-sensitive hypertension is associated with the T2238-->C mutation of the ANP precursor gene.

Losses at 3p common deletion sites in subtypes of kidney tumours: histopathological correlations

Deletions of the short arm of chromosome 3 (3p) have been recognized as characteristic features of clear cell renal cell carcinomas (clear cell RCC). We analysed 55 clear-cell RCCs and 30 non-clear-cell kidney tumours (10 papillary and 7 chromophobic RCCs, 11 oncocytomas and 2 collecting duct carcinomas) in loss of heterozygosity (LOH) studies using microsatellite markers for previously observed regions of common deletions on 3p in kidney tumours (3p25, 3p21.3, 3p14.2 and 3p12-13). Alterations were found in all 55 cases of clear-cell RCCs at two to four of the 3p regions. Extensive losses were not found in non-clear-cell tumours except for collecting duct carcinomas; 1 of 10 papillary RCCs showed interstitial deletion limited to a single 3p21.3 locus. LOH analyses using microsatellite markers for regions of common deletions at 3p may be of value in differential diagnosis of kidney tumours.

Mechanism of the inhibitory effect of curdlan sulfate on HIV-1 infection in vitro

To study the mechanism by which sulfated polysaccharides with 1,3-beta-D-glucan as a main chain exert anti-HIV-1 activity, we analyzed the effects of curdlan sulfate (CRDS) on HIV-1 infection of SupT-1 cells and peripheral blood mononuclear cells. CRDS had no effect on virions inhibited weakly HIV-1 attachment to cells, and had to be present for 24 hr to achieve protection. Lack of HIV-1 DNA corresponding to the gag region in cells incubated with the virus and CRDS and inhibition of infection after addition of 2',3'-dideoxyinosine to cells treated with CRDS and HIV-1 for less than 24 hr suggest that CRDS delays events that precede and/or include reverse transcription. Analysis of the effect of CRDS on binding of HIV-1 neutralizing antibodies to gp 120 demonstrated that both the continuous epitopes on the V3 loop and the discontinuous CD4 binding site of gp 120 represent targets for CDRS. This interaction of CRDS with functional gp 120 domains suggests that CRDS interferes with the membrane fusion process during HIV-1 infection. Concentrations of CRDS that were protective against infection with T cell- and macrophage-tropic HIV-1 isolates had less suppressive effects on T cell function in comparison with the related compound, dextran sulfate.

Analysis of gamma delta+ T cells in peripheral blood of children with perinatal human immunodeficiency virus (HIV) infection

The present study examined CD8 antigen expression and variable (V) gene segment usage by T cell receptor (TCR)-gamma delta+ lymphocytes in peripheral blood of symptomatic children with perinatal HIV infection. The relative number of gamma delta+, CD8+ T cells in most of the infected children was higher than that in uninfected children from HIV+ or HIV- mothers and correlated with the immunodeficiency status of the patients. Infected infants and children over 1 year old also showed an increased proportion of V delta 1-J delta 1+ T lymphocytes. CD8 expression on those cells was higher in infected than in uninfected infants and children. Sequence analysis of the delta gene rearrangement of the predominant V delta 1 family in peripheral blood of three HIV+ donors revealed extensive junctional diversity. These results suggest that the V delta skewing in the majority of HIV+ children reflects peripheral expansion of V delta 1-J delta 1+ T lymphocytes early in life, which might be involved in the mechanisms of HIV-induced immunodeficiency.