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Biomedical subjects

S Porcu

Publications and source records attributed to S Porcu.

17 recordsLinked to original sources
PubMed2001

The putative forkhead transcription factor FOXL2 is mutated in blepharophimosis/ptosis/epicanthus inversus syndrome.

In type I blepharophimosis/ptosis/epicanthus inversus syndrome (BPES), eyelid abnormalities are associated with ovarian failure. Type II BPES shows only the eyelid defects, but both types map to chromosome 3q23. We have positionally cloned a novel, putative winged helix/forkhead transcription factor gene, FOXL2, that is mutated to produce truncated proteins in type I families and larger proteins in type II. Consistent with an involvement in those tissues, FOXL2 is selectively expressed in the mesenchyme of developing mouse eyelids and in adult ovarian follicles; in adult humans, it appears predominantly in the ovary. FOXL2 represents a candidate gene for the polled/intersex syndrome XX sex-reversal goat.

Abnormalities, Multiple↗
PubMed2000

Rh system and intrauterine growth. Interaction with season of birth.

Based on the hypothesis that maternal-fetal genetic differences in membrane transport and signal transduction may influence intrauterine development, the recent acquisition on transport function of Rh protein prompted us to study the relationship between joint maternal-fetal Rh phenotype and birth weight. Considering that metabolic effect of maternal-fetal competition could be amplified by environmental conditions, we have investigated possible seasonal effects on such relationship. We have studied 5291 infants born in Sardinia in the period January 1993--December 1996 and 984 infants born in Rome during 1996. In Rh(-) mothers there is a significant association between season of birth and birth weight that shows the highest mean value in infants born in autumn (i.e. conceived in winter). The association is much more evident in male than in female infants. In male infants from Rh(-) mothers, the association between birth weight and season is significant in Rh(+) male newborns only. Recent observations by our group in NIDDM suggest that glucose transport in RBC may be related to D protein, thus we propose an interpretation of the present observation in terms of transport function. When the density of D protein in the infant is greater than in the mother, the balance is in favour of the infant who may attain a significant developmental advantage when conceived in the cold season.

Adult↗
PubMed1998

Transgenic knockout mice exclusively expressing human hemoglobin S after transfer of a 240-kb betas-globin yeast artificial chromosome: A mouse model of sickle cell anemia.

Sickle cell anemia (SCA) and thalassemia are among the most common genetic diseases worldwide. Current approaches to the development of murine models of SCA involve the elimination of functional murine alpha- and beta-globin genes and substitution with human alpha and betas transgenes. Recently, two groups have produced mice that exclusively express human HbS. The transgenic lines used in these studies were produced by coinjection of human alpha-, gamma-, and beta-globin constructs. Thus, all of the transgenes are integrated at a single chromosomal site. Studies in transgenic mice have demonstrated that the normal gene order and spatial organization of the members of the human beta-globin gene family are required for appropriate developmental and stage-restricted expression of the genes. As the cis-acting sequences that participate in activation and silencing of the gamma- and beta-globin genes are not fully defined, murine models that preserve the normal structure of the locus are likely to have significant advantages for validating future therapies for SCA. To produce a model of SCA that recapitulates not only the phenotype, but also the genotype of patients with SCA, we have generated mice that exclusively express HbS after transfer of a 240-kb betas yeast artificial chromosome. These mice have hemolytic anemia, 10% irreversibly sickled cells in their peripheral blood, reticulocytosis, and other phenotypic features of SCA.

Anemia, Sickle Cell↗
PubMed1998

Smooth pursuit and saccadic eye movements as possible indicators of nighttime sleepiness.

Sleepiness is associated with specific variations of spontaneous oculomotor activity. During nocturnal sleep onset periods and also during the Multiple Sleep Latency Test (MSLT) a reduction of both rapid eye movements and blinks are recorded. In many operational contexts it might be even more relevant to assess whether and to what extent voluntary visual ocular control is affected by sleepiness due to sleep deprivation and time-of-day effects. In this study we evaluated, in a laboratory simulation of a sudden inversion of the sleep-wake cycle, the nocturnal modifications of smooth pursuit (SP) and saccadic (SAC) eye movements as possible indicators of sleepiness. Levels of sleepiness were objectively measured by means of MSLT and Maintenance of Wakefulness Test (MWT); subjective ratings of sleepiness were also obtained. After a diurnal sleep, five subjects underwent four nocturnal test sessions, each one comprising an SP and a SAC trial. Both the SP variables considered (velocity gain and phase) showed a trend similar to that one of MWT latencies, being significantly impaired only in the last nocturnal trial, when levels of sleepiness were maximal. Saccadic accuracy showed the same trend, being negatively affected by sleepiness only in the last nocturnal session. In addition, percentage of rejected (inappropriate) saccades showed a linear increase during the night, paralleling the shortening of sleep latency at MSLT and the linear increase of subjective ratings of sleepiness. These results, suggesting that saccadic performance, unlike SP, seems to be more sensitive to increasing levels of sleepiness, encourage further research on this topic.

Adult↗
PubMed1998

Sleepiness, alertness and performance during a laboratory simulation of an acute shift of the wake-sleep cycle.

Monitoring the presence of sleepiness on the job and its effects on performance is of primary importance for improving schedule systems of shiftworkers. Shiftworkers, often involved in night-time operations and irregular work schedules, frequently complain of nocturnal sleepiness especially in conditions of abrupt shift of the wake-sleep cycle. In this study, the authors evaluated the effects of a laboratory simulation of acute night-shift changes on sleepiness, vigilance and performance, using Maintenance of Wakefulness Test, Multiple Sleep Latency Test and three pencil and paper tests: Digit Symbol Substitution Test, 'Deux Barrages' Test and a 3-Letter Cancellation Task. All of the tests were administered four times at 2-hourly intervals during the night after daytime sleep. Results showed that the ability to maintain wakefulness and to perform simple visuo-attentive tasks is substantially spared during the night. On the other hand, sleep tendency and performance on a more complex and monotonous task (Letter Cancellation Task) reveal, respectively, increasing sleepiness and degrading performance.

Adult↗
PubMed1997

The human beta globin locus introduced by YAC transfer exhibits a specific and reproducible pattern of developmental regulation in transgenic mice.

The human beta globin locus spans an 80-kb chromosomal region encompassing both the five expressed globin genes and the cis-acting elements that direct their stage-specific expression during ontogeny. Sequences proximal to the genes and in the locus control region, 60 kb upstream of the adult beta globin gene, are required for developmental regulation. Transgenic studies have shown that altering the structural organization of the locus disrupts the normal pattern of globin gene regulation. Procedures for introducing yeast artificial chromosomes (YACs) containing large genetic loci now make it possible to define the sequences required for stage-restricted gene expression in constructs that preserve the integrity of the beta globin locus. We demonstrate that independent YAC transgenic lines exhibit remarkably similar patterns of globin gene expression during development. The switch from gamma to beta globin predominant expression occurs between day 11.5 and 12.5 of gestation, with no more than twofold differences in human beta globin mRNA levels between lines. Human beta globin mRNA levels were twofold to fourfold lower than that of mouse betamaj, revealing potentially significant differences in the regulatory sequences of the two loci. These findings provide an important basis for studying regulatory elements within the beta globin locus.

Adult↗
PubMed1997

Determinants of functional status in healthy Italian nonagenarians and centenarians: a comprehensive functional assessment by the instruments of geriatric practice.

OBJECTIVE: To evaluate the physical ability and psychocognitive status of a population more than 90 years of age with regard to sociodemographic, behavioral, and biomedical variables known to affect functional status in old age. DESIGN: A survey design was used. SETTING: Emilia Romagna, Northern Italy. PARTICIPANTS: Eighty-four healthy community-dwelling subjects aged 90 to 106 years. MEASUREMENTS: Sociodemographic variables, health behavior, anthropometric indices, and serum DHEAS levels were recorded. Functional assessment was performed by instruments currently used in geriatric practice: the Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), and Activities of Daily Living (ADL) scale. A stepwise multiple regression analysis was performed. RESULTS: GDS scores correlated directly with MMSE scores and inversely with ADL severity scores. Poor education, institutionalization, sensory impairment, muscular mass loss, and lower DHEAS levels were the variables with the highest correlation to functional impairment. Smoking, alcohol consumption, and marital status were relatively unimportant. An inverse association was found between DHEAS levels and dependency scores of single ADLs (continence, mobility). CONCLUSION: Impaired cognitive and physical ability with no increase in depression prevalence was found in a sample of subjects more than 90 years of age free of major age-related disease. Muscular mass and DHEAS levels seem to play a role in maintaining physical independence. In turn, physical independence, as well as social and cultural factors, strongly affect the compliance of long-lived subjects with psychocognitive tests currently used in the clinical evaluation of younger old people, suggesting that these instruments are not reliable for screening for cognitive impairment and depression in the oldest old subjects.

Activities of Daily Living↗
PubMed1992

A beta-thalassaemia phenotype not linked to the beta-globin cluster in an Italian family.

This paper describes a family of Central Italian origin in which three patients in two generations had either thalassaemia intermedia or a late presenting form of thalassaemia major. Sequence analysis of the patients' DNA revealed that only one of the beta-globin genes was affected by a beta-thalassaemia mutation (the codon 39 nonsense mutation), the other being completely normal, apart from the complex rearrangement (-T +ATA) at position -530 5' to the CAP site of the beta-globin gene, which has uncertain clinical significance. Haematologically, all these patients were characterized by unusually low HbF levels (1.8-7.3%) for a beta-thalassaemia major or intermedia phenotype. The mother of the two patients with thalassaemia intermedia was heterozygous for beta-thalassaemia (codon 39 nonsense mutation), while the father had thalassaemia-like red cell indices, an increased alpha/non alpha chain synthesis ratio, a slight increase of HbF and a low HbA2 level, but showed entirely normal beta-globin gene sequences, apart from the complex rearrangement (-T +ATA) at position -530 5' to the CAP site. One of the thalassaemia intermedia patients married a normal woman and they had a child with thalassaemia major who inherited only the codon 39 nonsense mutation but not the complex rearrangement at position -530. The clinical phenotype of thalassaemia-intermedia or major in the patients from this family may be explained by postulating the inheritance of the double heterozygous state for beta-thalassaemia and for a mutation in a gene coding for an erythroid-specific DNA binding protein which may impair the function of the normal beta-globin gene. Heterozygosity for this postulated mutation (father of the patients with thalassaemia intermedia) may result in the production of a beta-thalassaemia carrier state with normal HbA2 level.

Adolescent↗
PubMed1992

A high frequency of the A30, B18, DR3, DRw52, DQw2 extended haplotype in Sardinian celiac disease patients: further evidence that disease susceptibility is conferred by DQ A1*0501, B1*0201.

This study characterizes by serological and molecular methods the HLA class I and class II alleles in a group of celiac disease children, their parents and a control group of Sardinian descent. We found the DR3-DQw2 haplotype in all patients which was, in almost all cases (84%), associated with the HLA-A30, B18, DR3, DRw52, DQw2 extended haplotype named "Sardinian haplotype" because of its frequency (12-15%) in this Caucasian population. This is the first time that this DQw2-linked haplotype has been reported with such a high frequency in CD. However, no different distribution of "Sardinian haplotype" was found comparing CD patients with 91 haplotyped DQw2-positive controls. This finding indicates that the DQw2 antigen in Sardinians is almost always associated with the A30, B18, DR3, DRw52, DQw2 extended haplotype. The DQA1 and DQB1 second exon sequence analysis of the B18,DR3 and B8,DR3 haplotypes showed the DQA1*0501 and DQB1*0201 alleles which shared the already published sequences. DPB1 subtyping showed the DPB1*0301 allele more frequently (p less than 0.005) in CD patients but this difference was no longer significant when patients and controls, both heterozygous for the DR3-DQw2 haplotype, were compared. We suggest that the divergent HLA extended haplotypes and DP allele associated with CD, described in different Caucasian populations, can be explained by the particular DQw2 linkage disequilibrium in each population.

Adult↗
PubMed1992

The HLA DQB1*0502 allele is neutrally associated with insulin-dependent diabetes mellitus in the Sardinian population.

In the Sardinian population a very high incidence of insulin-dependent diabetes mellitus (IDDM) and the lack of HLA-DR2 protective effect due to the high frequency of the A2, Cw7, B17, 3F31, DR2, DQw1 extended haplotype has been reported. This haplotype, carrying a Serine at position 57 of the DQB1*0502 allele, has been previously reported to be underrepresented in patients when compared to controls. In order to provide an explanation for this finding, we defined by RFLP analysis the HLA haplotype of 45 Sardinian IDDM patients and 49 controls. All DR-2DQw1 subjects were molecularly characterized at the HLA DQA and DQB loci. All DR2-positive patients and the vast majority of the DR2-positive controls had the DQB1*0502 allele at the DR2-linked DQB1 locus, with no statistically significant difference between the two groups. All DQA1 genes were the ones expected, with only two exceptions. Nine out of 10 of the DR2-positive patients were compound heterozygotes for DQB1*0201/DQB1*0502 alleles; only this allele combination was significantly increased (p less than 0.0003). Our data suggests that a) the DQB1*0502 allele is neutral for IDDM development and b) the susceptibility to IDDM in our DR2-positive patients is related to the compound heterozygous state between the neutral DQA1*0102/DQB1*0502 and the susceptibility DQA1*0501/DQB1*0201 alleles.

Adolescent↗
PubMed1990

The C-T substitution in the distal CACCC box of the beta-globin gene promoter is a common cause of silent beta thalassaemia in the Italian population.

This paper describes four families of Italian descent in each of which the propositus had the clinical phenotype of thalassaemia intermedia, resulting from the compound heterozygous state for high HbA2 beta thalassaemia and type I silent beta thalassaemia. Direct sequencing on amplified DNA and/or oligonucleotide analysis detected, in all families but one, the compound heterozygous state for codon 39 nonsense mutation and the C-T substitution at position -101 in the distal CACCC box of the beta-globin gene promoter (beta th-101). Members of these families who are heterozygous for high HbA2 beta thalassaemia showed the codon 39 nonsense mutation, while those with the clinical phenotype of silent beta thalassaemia had the beta th-101 mutation. In the remaining family, the propositus and one of his siblings had the compound heterozygous state for a molecularly undefined high HbA2 beta thalassaemia and the beta th-101 mutation in combination with the triple alpha globin gene arrangement. These patients showed a more severe thalassaemia intermedia like clinical phenotype as compared to those with the same beta-globin genotype and a normal alpha-globin gene arrangement. In the families investigated the beta th-101 was always associated with haplotype I. A group of patients with thalassaemia intermedia from Southern Italy, either homozygous or heterozygous for haplotype I and in whom previous studies had failed to define the mutation in one of the beta thalassaemia globin genes, were screened by oligonucleotide analysis for the presence of the beta th-101. Three out of nine were positive. These results indicate that the beta th-101 mutation is a common cause of the type I silent beta thalassaemia phenotype in the Southern Italian population.

Child↗
PubMed1988

Electroencephalography and visually evoked potentials during moderate hypoglycemia.

The effects of hypoglycemia per se on the electroencephalogram (EEG) and visually evoked potentials (VEPs) were studied in eight normal young adults. The EEG and VEPs were recorded before and during hypoglycemic clamp studies, carried out at plasma insulin and glucose concentrations of about 287 pmol/L and 2.38 mmol/L, respectively. From the mean power EEG spectra obtained during each testing condition, several parameters in each frequency band considered were compared statistically. During the eyes closed recording, the mean frequency of the alpha-band (8-13 Hz) decreased from 10.1 +/- 0.2 (+/- SE) Hz in both the right and left frontal leads during euglycemia to 8.8 +/- 0.2 and 8.8 +/- 0.1 Hz (left and right frontal leads, respectively; P less than 0.05) during hypoglycemia. In the same leads, the peak frequency decreased from 10.6 +/- 0.4 and 10.3 +/- 0.4 Hz to 9.6 +/- 0.4 and 9.5 +/- 0.3 Hz, respectively (P less than 0.05). A similar pattern of variation was found during the eyes open recording. In contrast, mean VEP latencies did not vary significantly; they were 118 +/- 3 ms (smallest image size; square wave signals subtending 30 min of arc) and 116 +/- 3 ms (largest image size; square wave signals subtending 60 min of arc) during euglycemia to 121 +/- 3 and 119 +/- 3 ms, respectively, during hypoglycemia. This study demonstrates that the earliest hypoglycemia-induced EEG alterations occur in the frontal regions and can be quantified in terms of decreased mean and peak frequencies of the alpha-band. VEP latency is less sensitive. If confirmed in diabetic patients, these data may provide a theoretical basis for developing a portable device to detect early hypoglycemia in those patients who lack warning symptoms.

Adult↗
PubMedDate not supplied

Activation of the delta-globin gene by the beta-globin gene CACCC motif.

The promoter region of adult beta globin genes in humans and other mammals contains conserved regions of pivotal importance for their regulated tissue specific expression. These include the CACCC and CAAT motifs. The CACCC motif is duplicated in humans and other mammals. The human delta-globin gene lacks these conserved regions and its expression in normal individuals is about 3% that of the beta globin gene. Previous studies have shown that the introduction of the beta-globin CACCC or CAAT can activate the delta-globin gene promoter, but the effect of the distal CACCC element has not yet been tested. In the present study, using site-specific mutagenesis, we have introduced the consensus sequence for the distal and proximal CACCC motif and the CAAT box alone or in combination in the wild-type delta-globin gene promoter. The resulting mutants, as well as the wild type (wt) delta- and beta-globin gene promoters, have been analyzed in a transient expression assay in Cos7, K562, and MEL cell lines. The results show that the CACCC boxes can increase the transcription efficiency of the delta-globin gene promoter in both erythroid and non-erythroid cell systems. The contribution of the two CACCC elements is almost equal in the non-erythroid (Cos7) and erythroid embryonic-fetal cell lines (K562), while the proximal CACCC element is more active in adult erythroid cells (MEL). Nonetheless, duplication of this element does not appear to affect the efficiency of the promoter synergistically. Furthermore, to assess the competitive ability of the delta globin promoter containing the proximal or distal CACCC consensus sequences over the wt beta globin gene promoter, we have carried out transient expression experiments using DNA constructs in which the delta and beta globin gene promoters are linked in cis and are sharing a single enhancer (competitive transient expression). The results show that both CACCC elements are able to activate the delta globin gene promoter in Cos7 and K562 cells, although to a different extent, whereas only the proximal CACCC element is effective in increasing the transcription efficiency in MEL cells. These findings are in agreement with the more severe clinical phenotype produced by the beta-thalassemia mutations affecting the proximal CACCC box as compared with those within the distal CACCC box. The Erythroid Kruppel Like Factor (EKLF) is a nuclear protein restricted to erythroid cells which specifically bind the CACCC box sequence and activate the beta-globin gene. In the present study we carried out transactivation experiments of the mutagenized delta-globin gene promoter by introducing an EKLF expressing construct in erythroid cells. Constructs containing the proximal but not those bearing the distal CACCC element are transactivated. Our results indicate that the proximal CACCC box and, to a lesser extent, also the distal box have a role in the regulated stage specific expression of a beta-like globin gene, and show that the insertion of a single CACCC motif in the delta-globin gene promoter is sufficient to increase its activity. Nevertheless only the delta globin gene promoter containing the proximal CACCC element is able to compete with the wt beta globin gene promoter in the adult erythroid environment. These findings have potential relevance for the future prospective treatment of inherited hemoglobinopathies based on the conversion of the low functioning delta-globin gene into a high functioning beta-like globin gene.

Animals↗