Association of tyrosine hydroxylase 01 (TH01) microsatellite and insulin gene (INS) variable number of tandem repeat (VNTR) with type 2 diabetes and fasting insulin secretion in Mexican population

PURPOSE

A variable number of tandem repeats (VNTR) in the insulin gene (INS) control region may be involved in type 2 diabetes (T2D). The TH01 microsatellite is near INS and may regulate it. We investigated whether the TH01 microsatellite and INS VNTR, assessed via the surrogate marker single nucleotide polymorphism rs689, are associated with T2D and serum insulin levels in a Mexican population.

METHODS

We analyzed a main case-control study (n = 1986) that used univariate and multivariate logistic regression models to calculate the risk conferred by TH01 and rs689 loci for T2D development; rs689 results were replicated in other case-control (n = 1188) and cross-sectional (n = 1914) studies.

RESULTS

TH01 alleles 6, 8, 9, and 9.3 and allele A of rs689 were independently associated with T2D, with differences between sex and age at diagnosis. TH01 alleles with ≥ 8 repeats conferred an increased risk for T2D in males compared with ≤ 7 repeats (odds ratio, ≥ 1.46; 95% confidence interval, 1.1-1.95). In females, larger alleles conferred a 1.5-fold higher risk for T2D when diagnosed ≥ 46 years but conferred protection when diagnosed ≤ 45 years. Similarly, rs689 allele A was associated with T2D in these groups. In males, larger TH01 alleles and the rs689 A allele were associated with a significant decrease in median fasting plasma insulin concentration with age in T2D cases; the reverse occurred in controls.

CONCLUSION

Larger TH01 alleles and rs689 A allele may potentiate insulin synthesis in males without T2D, a process disabled in those with T2D.

Beware: Gastrointestinal symptoms can be a manifestation of COVID-19

Background

There is a growing number of reports of COVID-19 cases presenting gastrointestinal (GI) symptoms.

Aims

To review studies reporting GI symptoms among COVID-19 patients.

Results

Fifteen papers (2800 patients) were identified. Frequency of GI symptoms varied from 3.0% to 39.6%, including diarrhea: 7.5%, nausea: 4.5%, anorexia: 4.4%, vomiting: 1.3%, abdominal pain: 0.5%, belching/reflux: 0.3%. These may be the first manifestation of COVID-19, however, there is controversy whether these reflect better or worst prognosis. Finally, the potential relationship with the angiotensin converting enzyme 2 (ACE2) cell receptor in the digestive tract as the virus entry route, is discussed.

Conclusions

GI symptoms may be common in COVID-19 and may be the first manifestation before fever and respiratory symptoms. Therefore, clinicians and gastroenterologists need to be aware of these atypical cases during the current pandemic and of the fecal–oral transmission, and preventive measures may be implemented.

Beware: Gastrointestinal symptoms can be a manifestation of COVID-19

BACKGROUND

There is an increasing number of reports on the presentation of gastrointestinal symptoms in cases of COVID-19.

AIM

To review the studies reporting gastrointestinal symptoms in COVID-19.

RESULTS

Fifteen articles (2,800 patients) were identified. Gastrointestinal symptom frequency varied from 3.0% to 39.6% and included diarrhea (7.5%), náusea (4.5%), anorexia (4.4%), vomiting (1.3%), abdominal pain (0.5%), and belching/reflux (0.3%). Those symptoms can be the first manifestation of COVID-19, but whether they reflect a better or worse prognosis, is controversial. The potential relation of the angiotensin converting enzyme 2 receptor in the digestive tract as an entry route for the virus is discussed.

CONCLUSION

Gastrointestinal symptoms may be common in COVID-19, in some cases appearing as the first manifestation, even before fever and respiratory symptoms. Therefore, clinicians and gastroenterologists must be aware of those atypical cases during the current pandemic, as well as of the fecal-oral route and corresponding preventive measures.

Wide allelic heterogeneity with predominance of large IDS gene complex rearrangements in a sample of Mexican patients with Hunter syndrome

Hunter syndrome or mucopolysaccharidosis type II (MPSII) is caused by pathogenic variants in the IDS gene. This is the first study that examines the mutational spectrum in 25 unrelated Mexican MPSII families. The responsible genotype was identified in 96% of the families (24/25) with 10 novel pathogenic variants: c.133G>C, c.1003C>T, c.1025A>C, c.463_464delinsCCGTATAGCTGG, c.754_767del, c.1132_1133del, c.1463del, c.508-1G>C, c.1006+1G>T and c.(-217_103del). Extensive IDS gene deletions were identified in four patients; using DNA microarray analysis two patients showed the loss of the entire AFF2 gene, and epilepsy developed in only one of them. Wide allelic heterogeneity was noted, with large gene alterations (e.g. IDS/IDSP1 gene inversions, partial to extensive IDS deletions, and one chimeric IDS-IDSP1 allele) that occurred at higher frequencies than previously reported (36% vs 18.9-29%). The frequency of carrier mothers (80%) is consistent with previous descriptions (>70%). Carrier assignment allowed molecular prenatal diagnoses. Notably, somatic and germline mosaicism was identified in one family, and two patients presented thrombocytopenic purpura and pancytopenia after idursulfase enzyme replacement treatment. Our findings suggest a wide allelic heterogeneity in Mexican MPSII patients; DNA microarray analysis contributes to further delineation of the resulting phenotype for IDS and neighboring loci deletions.

Connexin 30.2 is expressed in mouse pancreatic beta cells

Nowadays, connexin (Cx) 36 is considered the sole gap junction protein expressed in pancreatic beta cells. In the present research we investigated the expression of Cx30.2 mRNA and protein in mouse pancreatic islets. Cx30.2 mRNA and protein were identified in isolated islet preparations by qRT-PCR and Western blot, respectively. Immunohistochemical analysis showed that insulin-positive cells were stained for Cx30.2. Confocal images from double-labeled pancreatic sections revealed that Cx30.2 and Cx36 fluorescence co-localize at junctional membranes in islets from most pancreases. Abundant Cx30.2 tiny reactive spots were also found in cell cytoplasms. In beta cells cultured with stimulatory glucose concentrations, Cx30.2 was localized in both cytoplasms and cell membranes. In addition, Cx30.2 reactivity was localized at junctional membranes of endothelial or cluster of differentiation 31 (CD31) positive cells. Moreover, a significant reduction of Cx30.2 mRNA was found in islets preparations incubated for 24h in 22mM as compared with 3.3mM glucose. Therefore, it is concluded that Cx30.2 is expressed in beta and vascular endothelial cells of mouse pancreatic islets.

Asian-American variants of human papillomavirus 16 and risk for cervical cancer: a case-control study

BACKGROUND

Human papillomavirus 16 (HPV16) has a number of variants, each with a different geographic distribution and some that are associated more often with invasive neoplasias. We investigated whether the high incidence of cervical cancer in Mexico (50 cases per 100 000 women) may be associated with a high prevalence of oncogenic HPV16 variants.

METHODS

Cervical samples were collected from 181 case patients with cervical cancer and from 181 age-matched control subjects, all from Mexico City. HPV16 was detected with an E6/E7 gene-specific polymerase chain reaction, and variant HPV classes and subclasses were identified by sequencing regions of the E6 and L1/MY genes. Clinical data and data on tumor characteristics were also collected. All statistical tests were two-sided.

RESULTS

HPV16 was detected in cervical scrapes from 50.8% (92 of 181) of case patients and from 11% (20 of 181) of control subjects. All HPV16-positive samples, except one, contained European (E) or Asian-American (AA) variants. AA and E variants were found statistically significantly more often in case patients (AA = 23.2% [42 of 181]; E = 27.1% [49 of 181]) than in control subjects (AA = 1.1% [two of 181]; E = 10% [18 of 181]) (P<.001 for case versus control subjects for either E or AA variants, chi2 test). However, the frequency of AA variants was 21 times higher in cancer patients than in control subjects, whereas that ratio for E variants was only 2.7 (P =.006, chi2 test). The odds ratio (OR) for cervical cancer associated with AA variants (OR = 27.0; 95% confidence interval [CI] = 6.4 to 113.7) was higher than that associated with E variants (OR = 3.4; 95% CI = 1.9 to 6.0). AA-positive case patients (46.2 +/- 12.5 years [mean +/- standard deviation]) were 7.7 years younger than E-positive case patients (53.9 +/- 12.2 years) (P =.004, Student's t test). AA variants were associated with squamous cell carcinomas and adenocarcinomas, but E variants were associated with only squamous cell carcinomas (P =.014, Fisher's exact test).

CONCLUSIONS

The high frequency of HPV16 AA variants, which appear to be more oncogenic than E variants, might contribute to the high incidence of cervical cancer in Mexico.

Partially deleted SRY gene confined to testicular tissue in a 46,XX true hermaphrodite without SRY in leukocytic DNA

True hermaphroditism is an uncommon form of intersexuality in which testicular and ovarian tissue develop in the same individual. Most true hermaphrodites are 46,XX and lack SRY, the testis-determining gene. We describe results of molecular studies performed in a 46,XX true hermaphrodite SRY-negative in DNA from blood leukocytes but SRY-positive in DNA obtained from the testicular portion of the ovotestis. Surprisingly, the SRY identified in gonadal DNA carries a partial deletion at the 5' end of the gene. Our patient is the first case of a naturally occurring deletion within the SRY ORF (with a normal HMG box) and provides a new explanation for the abnormal gonadal development observed in 46,XX true hermaphrodites.

High prevalence of serum antibodies to Ras and type 16 E4 proteins of human papillomavirus in patients with precancerous lesions of the uterine cervix

Serum samples from 38 healthy women and 55 women with different types of cervical lesions were investigated for the presence of antibodies to Ras and against E4 and E7 proteins of human papillomavirus type 16 (HPV-16). Our results showed that anti-E7 antibodies were closely associated with cervical cancer (75%), as previously reported. Interestingly, E4 antibodies showed higher prevalence in condyloma lesions (79%; 11/14) than in cervical cancer (60%; 12/20). We also identified 11% (4/38) of healthy individuals as positive for E4 antibodies, which suggests an early immune recognition of this protein. Patients with condyloma and cervical intraepithelial neoplasia (CIN) also showed higher prevalences of Ras antibodies (approximately 40%) than cervical cancer patients (10%; 2/20). By sequencing part of the ras genes and using different Ras antigens, we showed that serum antibodies from patients were not directed to a Ras mutation, since wild-type cHa-Ras protein was recognized by these antibodies. In addition, patients positive for Ras antibodies (94%) were also positive for E4 antibodies, suggesting an association between these. The high prevalence of antibodies against Ras and E4 proteins in pre-malignant lesions opens the possibility of using both antibodies as early markers for potential cervical cancer patients.

Asian-american variants of human papillomavirus type 16 have extensive mutations in the E2 gene and are highly amplified in cervical carcinomas

Human-papillomavirus (HPV)-E2 protein is involved in gene-expression regulation and replication of HPV genome. Disruption of the E2 gene during viral integration has been proposed as a mechanism of tumoral progression, since the expression of E6/E7 viral oncogenes is allowed. However, retention of E1/E2 genes and high viral amplification are frequently found in HPV16-positive carcinomas of some populations. In this study, we investigated whether retention of E1/E2 and viral amplification are associated with particular HPV16 E2 variants in cervical carcinomas. HPV16 detection, E1/E2 integrity and viral amplification were explored by Southern blot in 123 cervical carcinomas. HPV16 variants were identified by Southern blot and by sequencing E6, L1/MY and E2 regions. Of 46 HPV16-positive tumors, 34 were positive for E1/E2 and 14 of them showed a variant restriction pattern by mutations in E2. All 14 were Asian-American (AA) variants and, of 11 sub-classified, 6 were AA-a and 5 AA-c. Two E1/E2-negative tumors also contained the AA-c variant, while the remaining HPV16-positive tumors contained only European variants. The E2 gene of AA variants showed 24 mutations, 19 identical in both sub-classes. The 24 mutations were distributed throughout the entire gene and 19 result in 18 amino-acid changes. The AA variants were associated with E1/E2-positive carcinomas with more than 50 viral copies/cell (p = 0.035). The association of Asian-American E2 variants with retention of E1/E2 suggests that E2 variation may be an alternative mechanism de-regulating the expression of viral oncogenes.

Therapeutic uterine-cervix cancer vaccines in humans

Infection with high-risk human papillomavirus (HPV) types is involved in early stages of uterine=cervix cancer development. The virally encoded E6 and E7 oncoproteins behave as tumor-specific antigens and represent targets for a vaccine designed to control HPV-induced tumors. Using either proteins or peptides based on E6 and E7 oncoproteins of HPV16 and 18, phase I clinical trials of therapeutic vaccines against HPV-associated cervical cancers have recently been reported. Although the effectiveness of these vaccines cannot be evaluated in such small studies, they constitute an important step toward the development of therapeutic uterine=cervix cancer vaccines. A polytope DNA vaccination approach combined with immunomodulatory cytokines may offer an excellent strategy to reduce the risk of relapse and metastasis following conventional therapies.

[Recombinant therapeutic vaccines against cancer of the uterine cervix]

Several mechanism to evade the immune system are induced during cervical cancer development, including the decrease of expression of class I HLA molecules and secretion of specific cytokines by tumoral cells. Consequently, the stimulation of cytotoxic (CTL) and helper (TH) T lymphocytes, as well as the natural killer (NK) cells and macrophages is very poor. The induction of immune response against tumors needs the stimulation of multiple components of the immune system: systemic stimulation of CTL and TH against Human Papilloma Virus epitopes and directly in the tumor the secretion of specific cytokines to increase the antigen processing and presentation of tumoral targets, and the stimulation of lymphocyte, NK cells and macrophages that infiltrate tumors.

The E7 protein of human papillomavirus (HPV) type 16 expressed by recombinant vaccinia virus can be used for detection of antibodies in sera from cervical cancer patients

Sera from 128 Mexican cervical cancer patients (age 30-80; mean 53.6) and from 47 healthy women (age 25-69; mean 49.2) were investigated using a newly developed assay for the detection of serum antibodies to the human papillomavirus (HPV) type 16 early protein E7. This test (CIPA), based upon immunoprecipitation followed by Western blot analysis, uses the complete E7 protein expressed in HeLa cells infected with recombinant vaccinia virus. To determine the sensitivity and specificity of this assay, these results were compared with previous results of the same sera tested by enzyme-linked immunosorbent assay (ELISA; using synthetic peptides derived from HPV 16 E7) and radio-immunoprecipitation (RIPA) using in vitro translated HPV 16 E7 protein. CIPA (45% positives) demonstrated a significant increase in detection rate compared to the peptide-ELISA (30% positives; P = 0.014, chi2-test) and only a slight increase compared to RIPA (38% positives; P = 0.204, chi2-test). Based on the testing of sera from patients with HPV 16 DNA positive tumors the specificity and sensitivity of the CIPA were 0.98 and 0.59, respectively.

Amplification of human papillomavirus types 16 and 18 in invasive cervical cancer

The distribution and amplification patterns of human papillomavirus were studied in 15 human papillomavirus (HPV) 16- and six HPV18-positive cervical carcinomas by colorimetric in situ hybridization (ISH). The findings were correlated with the viral copy number and status of E1/E2 viral genes in the tumor DNA, as studied by dot blot analysis and the polymerase chain reaction, respectively. The tumors were classified according to the ISH signal into single dot, multidot, diffuse, and mixed patterns. The signal was homogeneously distributed only in single dot tumors and was clearly heterogeneous in tumors with mixed nuclear signal patterns, including both dot and diffuse signals. The single dot pattern predominated in HPV 18-positive tumors (83%), whereas the multidot pattern was most frequent in HPV 16-positive tumors (47%). Diffuse and mixed patterns were noted only in HPV 16-positive tumors (33%). The lowest mean copy of number per cell was observed in single dot tumors (25 +/- 15) with an ascendent trend toward the diffuse signal tumors (2832 +/- 2281). E1/E2 genes were disrupted in 75% of the single/multidot tumors and in none of the diffuse/mixed tumors. These data suggest diffuse signals originate by episomal amplification and dot signals originate by viral integration. Diffuse and dot patterns suggest different mechanisms of viral transformation.

Antibodies against linear and conformational epitopes of the human papillomavirus (HPV) type 16 E6 and E7 oncoproteins in sera of cervical cancer patients

Sera obtained from 137 cervical cancer patients were analysed for the presence of antibodies to the human papillomavirus (HPV) type 16 proteins E6 and E7 by the aid of different assays, i.e. ELISA using as antigen either synthetic peptides or the complete E7 protein and radio-immunoprecipitation (RIPA) which uses the viral protein made by in vitro transcription/translation. In agreement with previous reports, reactivity to the E7 protein was found more frequently than to the E6 protein (31.4% vs. 16.8%) when the sera were assayed by peptide-based ELISA. In contrast, when RIPA was employed, reactivity to either protein was obtained at similar frequency (38.7% vs 46.7%). When the protein was denatured prior to immuno-precipitation the reactivity was lost in all sera tested for E6-specific antibodies but only in a few samples in the E7-RIPA. Therefore it was concluded that the increased sensitivity of the E6-RIPA as compared to the E6 peptide-ELISA is due to the detection of antibodies to conformational epitopes which are presented by the in vitro product but not by the synthetic peptides. Eighty-two sera from healthy donors were tested by HPV 16E6- and E7-RIPA and also by ELISA using the HPV 16E7 protein which was produced in the fission yeast Schizosaccharomyces pombe. One sample reacted each in the E6- and E7-RIPA indicating a high specificity of these assays. The E7 protein-ELISA proved to be less sensitive for the detection of antibodies in cervical cancer patients' sera (22.6% positive) as compared to peptide-based ELISA or RIPA.

Genome amplification of human papillomavirus types 16 and 18 in cervical carcinomas is related to the retention of E1/E2 genes

The level of amplification (copy number/cell) of HPV16 and HPV18 viral genomes and its correlation with the presence of E1/E2 genes were analyzed in a sample of 42 HPV16- and 21 HPV18-positive cervical carcinomas of different clinical stages and histological types. The viral copy number/cell was assessed by dot-blot hybridization and the presence of E1/E2 genes by PCR and Southern blot. The copy number/cell was significantly lower in HPV18-positive than in HPV16-positive tumours (23 +/- 8 and 457 +/- 191 respectively). Nearly half of the HPV16s (43%) were distributed similarly to the HPV18s in the ranges of 50 or less copies, having its peak at the group of 1 to 10 copies, whereas the remaining HPV16s (57%) spread over the groups of 51 or more copies, with another peak at the group of 101 to 500. The E1/E2 region was absent in all tumours positive for HPV18 and present in 64% of those positive for HPV16. The HPV16 tumours negative for E1/E2 had a much lower viral copy number (17 +/- 12) than the positive ones (582 +/- 212), thus resembling HPV18-positive tumours. Viral copy number was negatively correlated with the clinical stage of the tumours and directly associated with the degree of histological differentiation. However, these correlations are primarily attributable to the presence or absence of an intact E1/E2 region.