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Biomedical subjects

R Sanna

Publications and source records attributed to R Sanna.

At least 19 recordsLinked to original sources
PubMed2003

Identification of a mutant allele of the androgen receptor gene in a family with androgen insensitivity syndrome: detection of carriers and prenatal diagnosis.

We report the results of a molecular study of a large family segregating the complete form of the Androgen Insensitivity Syndrome (CAIS) in several family members from three generations. We identified the mutant allele by polymerase chain reaction (PCR) amplification of the short tandem repeat (CAG)n, highly polymorphic in the population, present in the first exon of the androgen receptor (AR) gene. In this family four different alleles were detected and one of these showed a perfect segregation with the disease. This study enabled us to identify the heterozygous females in this family. We think that this simple, indirect test, is also suitable for prenatal diagnosis of Morris' syndrome when the mother is heterozygous for the size of the short tandem repeat and one affected subject in the family may be studied.

Adolescent↗
PubMed2000

The prevalence and incidence of hepatitis C virus infections among dialysis patients in the Netherlands: a nationwide prospective study.

A nationwide prospective survey on hepatitis C virus (HCV) infections among dialysis patients in The Netherlands was performed. Patients were recruited from 34 dialysis centers and were tested for antibodies and HCV RNA in 1995 and 1997. Seronegative serum samples were analyzed by reverse-transcriptase polymerase chain reaction in pools. HCV-RNA-positive serum samples were genotyped and were partly sequenced. In the first and second rounds, 67 (2.9%) of 2281 and 76 (3.4%) of 2286 patients were HCV positive, respectively. Of 960 patients with paired serum samples, 35 were HCV positive in both rounds, and 9 HCV-positive cases were newly identified in the second round. The incidence of HCV infection was 0.5 per 100 dialysis years. Phylogenetic analysis revealed clustered sequences that indicated nosocomial transmission. Sixty percent of HCV infections, however, can be attributed to 4 interdependent risk factors (i.e., hemodialysis before 1992, kidney transplantation before 1994, and birth or dialysis in a foreign country). In conclusion, the prevalence of HCV infections in The Netherlands does not decline, and transmission within dialysis units continues. Adequate screening of HCV infections and strict enforcement of universal infection control practices are required.

Case-Control Studies↗
PubMed2000

Genetic organization and heterogeneity of the iceA locus of Helicobacter pylori.

The genetic organization and sequence heterogeneity of the iceA locus of Helicobacter pylori was studied, and the existence of two distinct gene families, iceA1 and iceA2, at this locus was confirmed. iceA1 has significant sequence homology to nlaIIIR, encoding an endonuclease in Neisseria lactamica, but the similarity at the protein level is limited, due to frameshift mutations of iceA1 in most H. pylori strains. In only five of the 19 iceA1 strains studied, a full-length open reading frame (ORF), capable of encoding a 228aa protein, with 52% homology to NlaIII was observed. The region upstream of iceA2 is highly variable in length, containing up to 15 copies of 8bp tandem repeats. iceA2 can encode proteins of 24, 59, 94, or 129 amino acids, consisting of 14 and 10aa domains, conserved in all iceA2 strains, flanking 0, 1, 2, or 3 copies of a 35aa cassette. This 35aa cassette consists of domains of 13, 16 and 6aa, respectively. The 13aa and 6aa domains are highly conserved, but the 16aa domain exists in two variants. In total, five distinct iceA2 subtypes were defined. Database searches did not reveal any homologous sequences. Recombinant IceA1 and IceA2 proteins were expressed in Escherichia coli, confirming the predicted ORFs. Genotype-specific PCR primers permitted iceA genotyping in 318 (99. 1%) of a worldwide collection of 321 H. pylori strains. The conserved sizes of the amplification products confirmed the worldwide distribution of discrete variants of iceA1 and iceA2.

Amino Acid Sequence↗
PubMed1999

Geographic distribution of vacA allelic types of Helicobacter pylori.

BACKGROUND & AIMS: Distinct allelic types of Helicobacter pylori vacA have been defined. The geographic distribution of vacA alleles and cagA was assessed in this study. METHODS: A total of 735 cultures from patients in 24 countries were analyzed by polymerase chain reaction and reverse hybridization on a line probe assay (LiPA). RESULTS: In 124 (16.9%) of the 735 cultures, multiple vacA genotypes were detected, permitting analysis of 611 strains. In Europe, a distribution gradient of s1 subtypes was observed. In northern and eastern Europe, 89% were subtype s1a. s1a and s1b were equally present in France and Italy, whereas in Spain and Portugal 89% of strains were subtype s1b. s1a and s1b were approximately equally prevalent in North America. In Central and South America, virtually all s1 strains were subtype s1b. Subtype s1c was observed in 77% of the s1 isolates from East Asia. m1 and m2a have equal presence, except on the Iberian peninsula and in Central and South America, where m1 (86.2%) is more prevalent than m2 (13.8%). Subtype m2b was found exclusively among East Asian s1c strains. In all parts of the world, vacA s1/cagA-positive genotypes were associated with peptic ulcer disease (P < 0.001). CONCLUSIONS: These data indicate a geographic distribution of H. pylori genotypes and aid in understanding the relationship of H. pylori with disease.

Alleles↗
PubMed1999

Rapid detection, by PCR and reverse hybridization, of mutations in the Helicobacter pylori 23S rRNA gene, associated with macrolide resistance.

A PCR-based reverse hybridization system (research prototype kit INNO-LiPA for H. pylori resistance) was developed and evaluated for simultaneous detection of 23S ribosomal DNA point mutations, associated with macrolide resistance in Helicobacter pylori. Fifty-seven H. pylori strains (51 natural, 6 laboratory-derived artificial, 52 resistant, and 5 susceptible strains) were tested by PCR-LiPA (detecting mutations A2115-->G, G2141-->A, A2142-->G, A2142-->C, A2143-->G, A2143-->C, and A2143-->T), DNA sequencing, restriction fragment length polymorphism, and/or hybridization to oligonucleotide probes. Results were highly concordant, but PCR-LiPA appears to be more sensitive for the simultaneous detection of multiple mutants.

Anti-Bacterial Agents↗
PubMed1999

Distinct variants of Helicobacter pylori cagA are associated with vacA subtypes.

The diversity of the cytotoxin-associated gene (cagA) of Helicobacter pylori was analyzed in 45 isolates obtained from nine countries. We examined variation in the 5' end of the cagA open reading frame as determined by PCR and sequencing. Phylogenetic analysis revealed the existence of at least two distinct types of cagA. One variant (cagA1) was found exclusively in strains from Europe, the United States, and Australia, whereas a novel variant (cagA2) was found in strains from East Asia. The greatest diversity between cagA1 and cagA2 was found in the first 20 amino acids of the cagA open reading frame, where several consistent insertions or deletions were observed. Additional cagA sequence variants that could be classified as separate subtypes were found in two of three Peruvian and in five of seven U.S. strains tested. The calculated isoelectric point of the first 154 amino acids of the cagA1 variants (7.52 +/- 1.54) was significantly higher than that of the first 154 amino acids of the cagA2 variants (5.61 +/- 0.94; P < 0.001). Most cagA2 strains contained vacA subtype s1c (P < 0.001), and in vacA m1 strains cagA1 was more frequently observed than cagA2. These results show the epidemiological relationship between cagA and vacA at the subtype level and indicate the existence of distinct H. pylori lineages that are not uniformly distributed over the globe.

Antigens, Bacterial↗
PubMed1998

Clinical relevance of the cagA, vacA, and iceA status of Helicobacter pylori.

BACKGROUND & AIMS: Clinical outcome of Helicobacter pylori infection may be associated with specific virulence-associated bacterial genotypes. The aim of this study was to assess the relationships between H. pylori cagA, vacA, and iceA status and severity of disease. METHODS: Gastric biopsy specimens from 94 patients in The Netherlands were analyzed by polymerase chain reaction and reverse hybridization. RESULTS: cagA was present in 63 (67%) of 94 cases and was associated with peptic ulcer disease (P = 0.0019). vacA geno-types s1a/m1, s1b/m2, s1b/m1, s1b/m2, and s2/m2 were found in 36.2%, 23.4%, 2.1%, 5.3%, and 20.2%, respectively. Ten isolates (10.6%) contained multiple vacA genotypes. The presence of peptic ulcers was associated with type s1 strains (P = 0.0006) but not with the m type (P = 0.2035). cagA and vacA s1 were strongly associated (P < 10(-5)). iceA1 was found in 53 (56.4%) and iceA2 in 25 (26.6%) of the 94 cases. In 14 isolates (14.9%), both iceA alleles were found, and 2 (2.1%) were negative for both iceA1 and iceA2. iceA1 was also associated with peptic ulcer disease (P = 0.0042). The iceA allelic type was independent of the cagA and vacA status. CONCLUSIONS: vacA s1, cagA, and iceA1 are markers of H. pylori strains that are more likely to lead to ulcer disease.

Adult↗
PubMed1998

Expanding allelic diversity of Helicobacter pylori vacA.

The diversity of the gene encoding the vacuolating cytotoxin (vacA) of Helicobacter pylori was analyzed in 98 isolates obtained from different geographic locations. The studies focused on variation in the previously defined s and m regions of vacA, as determined by PCR and direct sequencing. Phylogenetic analysis revealed the existence of four distinct types of s-region alleles: aside from the previously described s1a, s1b, and s2 allelic types, a novel subtype, designated s1c, was found. Subtype s1c was observed exclusively in isolates from East Asia and appears to be the major s1 allele in that part of the world. Three different allelic forms (m1, m2a, and m2b) were detected in the m region. On the basis of sequence alignments, universal PCR primers that allow effective amplification of the s and m regions from H. pylori isolates from all over the world were defined. Amplimers were subsequently analyzed by reverse hybridization onto a line probe assay (LiPA) that allows the simultaneous and highly specific hybridization of the different vacA s- and m-region alleles and tests for the presence of the cytotoxin-associated gene (cagA). This PCR-LiPA method permits rapid analysis of the vacA and cagA status of H. pylori strains for clinical and epidemiological studies and will facilitate identification of any further variations.

Amino Acid Sequence↗
PubMed1992

Graft-versus-leukemia effects after allogeneic bone marrow transplantation are active also in the presence of clones with chromosomal anomalies in addition to the Ph chromosome.

Two male patients with Philadelphia-chromosome (Ph+) chronic myelogenous leukemia (CML) underwent allogeneic bone marrow transplantation (ABMT) in the first chronic phase after busulfan treatment. In both cases, the donor was a sister, and engrafting was demonstrated by chromosome analyses which showed only donor cells in the BM. Cytogenetic relapse occurred 29 and 30 months after ABMT, respectively, when host cells reappeared: in both cases, the Ph and additional anomalies typical of the blastic phase of CML were evident. We then monitored the chromosome picture for 52 and 39 months, respectively: no striking evolution occurred, and cells with the Ph and additional anomalies persisted together with donor cells, which were a minority in the first patient and a great majority in the second throughout the observation period. A clinical relapse was observed in the first patient, but the disease never progressed to a blastic phase, whereas the second patient has not relapsed 7 years after ABMT. We reviewed data from the literature on cytogenetic relapse after ABMT in CML without clinical relapse, especially the 12 patients in whom cytogenetic relapse included chromosome anomalies in addition to the Ph, as in our patients. We suggest that graft-versus-leukemia (GVL) reactions in such patients are able to arrest progression of the leukemic blastic clone and prevent a possible relapse in blastic phase.

Bone Marrow Transplantation↗
PubMed1992

Isolation of pig pancreatic islets by a new method with hydraulic shaking: preliminary report.

The limited availability of human pancreas represents a serious problem in islet transplantation. In the past few years many efforts have been made to isolate pancreatic islets from large mammals in order to achieve valid and reproducible isolation methods. For several reasons swine may be considered an ideal source of islet tissue because of the similarity between human and porcine insulin and because of the easy availability of pig pancreata. Some papers have been published recently on this topic with good results. However, some problems, such as islet dissociation into single cells after collagenase digestion, are not completely solved. In this article, an automated method involving a hydraulic shaking system is described for islet isolation from the pig pancreas, developed in our laboratory and derived from Ricordi's model.

Animals↗
PubMedDate not supplied

Effect of low-dosage recombinant human growth hormone therapy on pulmonary function in hypopituitary patients with adult-onset growth hormone deficiency.

An impairment of the pulmonary function has been described in adult patients with childhood-onset growth hormone deficiency (GHD). We examined forced vital capacity (FVC), forced expiratory volume (FEV1), total lung capacity (TLC), functional residual capacity (FRC), residual volume (VR) and the index of inspiratory strength, middle tidal volume and tidal inspiratory time ratio (TV/I), in 29 patients with adult-onset GHD. Data were compared with those obtained in 46 healthy control subjects. Only the FEV1/FVC ratio was statistically different (p = 0.04) between the two groups of subjects. In a group of 15 GHD patients low dosages (0.5-1 IU/day s.c., bedtime) of recombinant human GH (rh-GH; n. = 8 subjects) or placebo (n. = 7) were given at random for a 6-month period. A significant increase in IGF-I levels was noted in the rh-GH-treated group (p = 0.04) but not in the placebo group. After the 6-month period no statistically significant changes in pulmonary function were found between the rh-GH-treated and placebo-treated GHD patients. This study shows that adult-onset GHD patients suffer from minimal impairment of pulmonary function. Low rh-GH dosages able to induce an increase in IGF-I levels do not improve pulmonary function. The effect of rh-GH on respiratory muscle strength could be related to the age at which GHD diagnosis is made, or induced only by high rh-GH dosages given for a long time.

Adult↗
PubMedDate not supplied

Monte Carlo dosimetry for 125I and 60Co in eye plaque therapy.

Monte Carlo calculations of radiation dosimetry using MORSE code are performed for 125I and 60Co point sources in a cylindrical head phantom that simulates the geometry of eye plaque therapy for choroidal melanoma. We obtain the dose variation in the eye at submillimeter intervals over distances as close as 1 mm and up to 2.5 cm from the source. The calculations for 125I are performed for the phantom media of water, protein, and a homogenized protein-water mixture simulating the composition of the eye. Relative dose functions for 125I for these phantom media are fitted to second-degree polynomials. Agreement is found with published results. The relative dose function for 60Co at eye position in the water head phantom is fitted to a third-degree polynomial and compared with that for 60Co at the center of a large water sphere. A boundary effect due to the head phantom-air interface on the dose distribution for 60Co is demonstrated. The dose falloff with distance is faster for the eye geometry compared with the bulk geometry. We also show that the relative dose distributions within the tumor are comparable for 125I and 60Co by comparing their relative dose functions. This result is consistent with the success of clinical trials of large melanoma treatments with 125I plaques.

Biophysical Phenomena↗
PubMedDate not supplied

Dose rate determination for 125I seeds.

Dose rates in water have been determined for the two types of 125I seed currently used in brachytherapy. The need for such determinations became evident when water/air ratios measured with a silicon diode were found to be lower than expected. Extensive measurements using lithium fluoride thermoluminescent dosimeters (TLD's) have been performed in a solid water phantom, at distances from 0.1 to 10 cm from the seed center and at angular increments of 10 degrees, 15 degrees, or 30 degrees within a plane through the seed axis. Dose calibration of the TLD's was accomplished by irradiation in air with 125I seeds of the same type and of strengths traceable to a calibration at the National Institute of Standards and Technology (NIST). Relative calibration of TLD's was monitored by irradiation, in an oven-type x-ray machine, of control dosimeters simultaneously and all dosimeters intercurrently with the 125I irradiations. Values obtained for the dose rate constant, i.e., dose rate per unit air-kerma strength at 1 cm on the transverse axis, were 0.853 and 0.932 cGy h-1 U-1 (1.08 and 1.18 cGy h-1 mCi-1) for the 6711 and 6702 seeds, respectively. Measured data were supplemented with Monte Carlo-calculated relative dose rate data generated using the MORSE code. These calculations used 100 energy groups from 10 to 35.4 keV and involved energy collection bins ranging from 0.025 to 1.2 cm on an edge. Normalized at 1 cm, transverse axis calculated data are not significantly different from measured data (ours or cited literature) at distances either less than 2.5 or greater than 8 cm. Normalized at different distances along the transverse axis, our off-axis calculated and measured distributions agree closely at all angles but differ from literature measured distributions at small (less than or equal to 1 cm) distances and, for small angles, increasingly at larger distances (greater than or equal to 5 cm).

Brachytherapy↗