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Biomedical subjects

M Zuccotti

Publications and source records attributed to M Zuccotti.

At least 37 records · Page 2Linked to original sources
PubMed1997

XIST expression in human oocytes and preimplantation embryos.

During mouse preimplantation development, the exclusive expression of the Xist gene from the paternally inherited allele is thought to play a role in the inactivation of the paternally inherited X chromosome in the extra-embryonic cell lineages of the developing female embryo. Recently, inactivation of the paternally inherited X chromosome has also been shown to occur in the extraembryonic cell lineages of the human female conceptus. In this paper, we determine whether the pattern of XIST expression in human preimplantation embryos is similarly correlated with paternal X inactivation. We developed procedures sensitive to the single cell, for the simultaneous analysis of XIST and HPRT expression and of sexing, initially using human fibroblast cells. Application of these procedures to human cleavage-stage embryos derived by in vitro fertilization revealed a pattern of XIST expression different from that in the mouse. Transcripts of the XIST gene were detected as early as the 1-cell zygote and, with increasing efficiency, through to the 8-cell stage of preimplantation development. In addition, transcripts of XIST were detected in both male (hence from the maternally inherited allele) and female preimplantation embryos. This pattern of expression is not consistent with a role for the early expression of the XIST gene in the choice of paternal X inactivation in the extraembryonic cell lineages of the developing human embryo.

Animals↗
PubMed1997

Genome composition in Venezuelan spiny-rats of the genus Proechimys(Rodentia, Echimyidae). I. Genome size, C-heterochromatin and repetitive DNAs in situ hybridization patterns.

The genome sizes of the Venezuelan spiny-rats Proechimys guairae guairae (2n = 48) and P. trinitatis (2n = 62) were evaluated and proved to be 12.5 +/- 0.5 pg and 12.6 +/- 0.3 pg respectively, the highest so far recorded among mammals; also the C-heterochromatin (32.7%, Coefficient of Variation [CV] 3.8 and 35.8%, CV 4.4) and GC (44.2%, CV 2.7 and 43.6%, CV 2.9) contents are very high. Highly repetitive (rep) DNAs were isolated from restriction enzyme digested genomic DNAs of both species. The intra- and inter-specific chromosomal allocations of these rep DNAs were analyzed by direct and cross-hybridizations. Results show that the two genomes harbour several rep DNA families which show both species-specificity and interspecific relatedness in their in situ hybridization patterns. The rep DNA families show an equilocal distribution at both the pericentromeric areas of all chromosomes and in the whole arms of two pairs of the uniarmed group, suggesting co-evolution of the rep DNAs. P. g. guairae BamHI digested DNA, when cloned and sequenced, proved to consist of a long "composite" unit (1,239 bp) containing two copies of each of 75-bp and 110-bp internal subrepeats. Karyotype restructuring between P. g. guairae and P. trinitatis, mainly due to Robertsonian changes, was accompanied by slight intra- and intergenomic movements of the putative satellite DNA families within stable genome sizes and C-heterochromatin contents. We discuss the findings obtained in Proechimys in the light of those regarding the kangaroo rat, the pocket gopher and the house mouse; they support the idea that karyotype restructuring could be the expression of molecular driven events of rep DNA amplification and homogenisation through non-homologous chromosomes.

Animals↗
PubMed1995

Chromatin organization during mouse oocyte growth.

We investigated the changes in the organization of oocyte nuclear chromatin and nucleolar-associated chromatin throughout folliculogenesis. Zona-free oocytes were isolated from ovaries, grouped into seven classes according to size and chromatin organization, and analyzed after staining with Hoechst 33342. We show that oocyte differentiation from the dictyate stage to the conclusion of maturation is associated with either of two chromatin configurations. Initially, all oocytes are in the NSN configuration (nonsurrounded nucleolus oocytes; characterized by a Hoechst positive-chromatin pattern of small clumps forming a network on the nuclear surface, with a nucleolus nonsurrounded by chromatin). While growing some of these NSN oocytes continue their development in the NSN configuration, whereas others shift (from class IV on) into the SN configuration (surrounded nucleolus oocytes; characterized by a threadlike chromatin organization that may partially surround the nucleolus or project towards the nuclear periphery). The percentage of SN oocytes increases both with increasing size of the oocyte (class I-III, 10-40 microns in diameter: 100% NSN vs. 0% SN; class VII 70-80 microns in diameter: 47.3% NSN vs. 52.3 SN, in 4-6-week-old females), and with aging (class VII: 94.1% NSN vs. 5.9% SN in 2-week-old females; 11.8% NSN vs. 8.2% SN in 56-week-old females). Further, we suggest as a working hypothesis that those oocytes that switch to the SN chromatin organization early in maturation may not be ovulated, even though this particular chromatin structure normally occurs just prior to ovulation.

Animals↗
PubMed1995

Methylation of the mouse Xist gene in sperm and eggs correlates with imprinted Xist expression and paternal X-inactivation.

Preferential paternal X-inactivation in the extra-embryonic tissues of the female mouse embryo is correlated with imprinted expression of the paternal allele of the Xist gene in pre-implantation development. Here we examine 11 CpG sites in Xist to determine whether differential methylation might be the molecular basis for imprinting. We find that three sites in the promoter region are methylated in eggs but not in sperm and that this differential methylation is maintained to the blastocyst stage when the paternal X-inactivation occurs. This is the first example of a primary gametic methylation imprint governing differential expression of parental alleles in pre-implantation embryos.

Animals↗
PubMed1994

Development and loss of the ability of mouse oolemma to fuse with spermatozoa.

To further our knowledge on the mechanisms and molecules involved in mouse sperm-oocyte plasma membrane interaction, experiments were carried out to determine the stage during oogenesis at which an oocyte acquires the capacity to fuse with acrosome-reacted sperm. Zona-free oocytes 10 microns in diameter do not fuse with sperm. Oolemma fusibility is first acquired when the oocyte reaches about 20 microns in diameter. Fusibility is maintained even after fertilisation has occurred and is lost completely by the 4-cell stage.

Acrosome↗
PubMed1994

Polymyositis-like syndrome in hypothyroidism: report of two cases.

An increase of muscle enzymes in hypothyroidism has sometimes been correlated with a polymyositis-like syndrome and hypothyroid patients have been misdiagnosed and mismanaged as suffering from polymyositis. Actually, muscle symptoms, such as aches and pain, stiffness, weakness and cramps or, more rarely, hypertrophy, are observed in hypothyroidism and increased serum muscle enzyme values, particularly the level of creatine phosphokinase (CPK), indeed seem to suggest polymyositis. The muscular groups most commonly affected by the above mentioned symptomatology are those of the shoulder and pelvic girdles. In this report two hypothyroid patients complaining of muscle symptoms, whose serum muscle enzymes were particularly elevated, are described. In the first case the patient had been suffering from pain and weakness of the thenar eminence for about 4 months. The clinical features suggested a diagnosis of Carpal Tunnel Syndrome, but thyroid function tests revealed primary hypothyroidism. In the second case the patient had been afflicted with muscular weakness of the shoulder girdle for 2 months and was unable to keep his arms raised over his head. A study of thyroid function demonstrated a picture of hypothyroidism. Both patients were treated with L-thyroxine and in a relatively short time biochemical parameters improved remarkably, and the symptoms disappeared. The hypothesis that a muscular effort of long duration by hypothyroid patients may have been responsible for the muscular damage and the symptoms may explain why only a few hypothyroid patients develop a clinical picture similar to polymyositis.

Adult↗
PubMed1993

Polymerase chain reaction for the detection of methylation of a specific CpG site in the G6pd gene of mouse embryos.

This chapter describes the polymerase chain reaction (PCR) detection of methylation changes at specific CpG sites in DNA isolated from minute quantities of biological material, such as single preimplantation mouse embryos or small numbers of stem cells, or germ cells. We have concentrated on refining these techniques to monitor specific sites in X-linked genes for methylation changes associated with X-chromosome inactivation. The general principles of the HpaII-sensitive PCR assay described here should be applicable and adaptable to specific CpG sites in other genes of interest.

Animals↗
PubMed1992

Methylation of CpG sites of two X-linked genes coincides with X-inactivation in the female mouse embryo but not in the germ line.

To further our understanding of initiation and imprinting of X-chromosome inactivation, we have examined methylation of specific CpG sites of X-linked Pgk-1 and G6pd genes throughout female mouse development. Methylation occurs around the time of inactivation and earlier for Pgk-1, which is closer to the X-inactivation centre. In female primordial germ cells, the inactive X chromosome escapes methylation; this may underly the reversibility of inactivation at meiosis. Similarly, the genes are unmethylated on the inactive X chromosome in sperm; hence, the imprint specifying preferential X-inactivation in extra-embryonic tissues must reside elsewhere.

Animals↗
PubMed1991

The ability of hamster oolemma to fuse with spermatozoa: its acquisition during oogenesis and loss after fertilization.

To determine when the growing hamster oocyte gains the ability to fuse with the spermatozoon, oocytes at various stages of development were collected from ovaries, and zona-pellucida-free oocytes were inseminated in vitro with acrosome-reacted spermatozoa. Very small primary oocytes were unable to fuse with spermatozoa. Oocytes first became competent to fuse with spermatozoa when they had grown to about 20 microns in diameter. The acquisition of fusibility coincided with the first appearance of zona pellucida material and oolemma microvilli. The fusibility of the oolemma increased as the oocyte grew, reaching a maximum when the oocyte reached the metaphase of the second meiosis. The fusibility of the oolemma was reduced drastically after fertilization, and was lost completely by the 8-cell stage. The appearance and subsequent disappearance of a putative fusion-mediating molecule in the oolemma is proposed. Since this molecule is fairly resistant to proteinase digestion, at least in the hamster, it could be a cryptic protein or a glycolipid.

Animals↗
PubMed1991

Collagenase as an agent for dissolving the zona pellucida of hamster and mouse oocytes.

Crude preparations of collagenase, which have been used commonly for tissue dissociation, contain proteases that dissolve zonae pellucidae of hamster and mouse oocytes without reducing the ability of the oolemma to fuse with spermatozoa. This gentle proteolytic removal of zona is particularly useful for the study of sperm-oocyte fusion in mice, as trypsin, chymotrypsin and pronase damage the mouse oolemma.

Animals↗
PubMed1990

Kinetics of oogenesis in mice heterozygous for Robertsonian translocation.

The total number of oocytes at different postmating time intervals (18-40 days) was determined in mice homozygous and heterozygous for different Robertsonian (Rb) translocations, of both laboratory and feral origin. The number of oocytes was lower in heterozygous than in homozygous mice throughout the period studied. Independently of the genetic background (i.e. laboratory or feral), structural heterozygosity had a progressive detrimental effect on oocyte numbers: open, or chain diakinetic configurations had a greater detrimental effect than close, or ring, configurations. The genetic background, however, affected the ovarian constitution in terms of the total number of germ cells, which are more numerous in laboratory than in feral mice. The kinetics of oogenesis seems to be faster in feral than in laboratory mice. At the light of the data here presented, and of those already available from the literature on male and female gametogenesis in conditions of structural heterozygosity, it appears that factors other than unsaturation of pairing sites or interference with pachytene X-chromosome inactivation have to be considered. In the wild, the reduced oocyte numbers in Rb heterozygous female can contribute to the retention of isolated populations in contact zones.

Animals↗
PubMed1990

Effectiveness and safety of etodolac in treatment of rheumatoid arthritis: a multicentre two-months' open study.

One hundred and seventeen outpatients (87 females and 30 males; mean age 53.5 +/- 13.2 years) encompassing the 1987 American Rheumatism Association criteria for rheumatoid arthritis were admitted into a multicentre open study. All patients were evaluated at baseline and after two months of therapy with etodolac (400 or 600 mg/die per os). Clinical evaluation was performed by using the following indicators: viso-analogic scale of global pain; index of pain on active movements; index for sleep disturbances, and duration of morning stiffness. The erythrocyte sedimentation rate was chosen for the laboratory evaluation of the activity of the disease. One hundred patients received 400 mg/die, while only 17 patients received 600 mg/die; 115 patients undertook the evaluation after treatment, whereas two patients were considered "lost to follow-up". One hundred and five patients completed the study while ten patients withdrew (seven because of inefficacy and three because of intolerance of the gastrointestinal tract). Only nine patients presented side-effects, among these: five were judged etodolac-related, whereas four were not. A complete resolution of all these side-effects was achieved in all cases. Significant improvements were registered for all the four clinical variables. At the end of the study 56.5% of patients expressed a preference for etodolac, 16.5% for one of the non-steroidal anti-inflammatory drugs previously taken and 27% did not answer or were not able to express any definite preference. Strict concordance was found between the degree of clinical improvement achieved and the preferences expressed. The laboratory parameters did not reveal any variation at the end of the study in comparison with baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Spermatogenesis in heterozygotes for Robertsonian chromosomal rearrangements from natural populations of the common shrew, Sorex araneus.

Twenty-two adult male common shrews were collected from 5 sites in the vicinity of Oxford (UK) close to the zone of hybridization between two karyotypic races. The shrews were subdivided into 3 karyotypic categories: homozygotes, simple Robertsonian heterozygotes (which form one or more trivalents at prophase I of meiosis) and complex Robertsonian heterozygotes (which form a quadrivalent). The ratio of primary spermatocytes to round spermatids was determined from transverse sections of seminiferous tubules, to provide an indication of germ cell death. In no individual was there severe germ cells loss. Homozygotes had the highest mean spermatocyte: spermatid ratio and complex heterozygotes the lowest, but there was substantial individual variation and the differences were not significant. Complex heterozygotes also had a higher proportion of defective seminiferous tubules and lower testis weights than did other categories and it is reasonable to propose that, as a population, complex heterozygotes had reduced fitness relative to other categories on the basis of spermatogenic performance. However, there is no evidence from studies of spermatogenesis that simple Robertsonian heterozygotes are less fit than homozygotes.

Animals↗
PubMed1988

Genome size and constitutive heterochromatin in Hylobates muelleri and Symphalangus syndactylus and in their viable hybrid.

Genome size was measured as the amount of Feulgen-stained DNA in six species of the family Hylobatidae and in a hybrid of the gibbon (Hylobates muelleri) and siamang (Symphalangus syndactylus). The family, on the whole, exhibits a wider range of genome sizes than pongids; in particular, the siamang has about 15% more DNA than the 44-chromosome Hylobates species of the "lar" group. Quantitative analysis of C-heterochromatin in hybrid metaphases showed that the difference in genome size of the parental species correlates with the amount of C-band-positive material. Hylobatids are the only group of primates in which karyotype diversification has taken place with a massive quantitative change in constitutive heterochromatin.

Animals↗
PubMed1987

Plasma levels of fibronectin in polymyalgia rheumatica giant cell arteritis.

In order to verify whether measurement of plasma fibronectin (Fn) could represent a useful tool in acute-phase-response assessment, Fn was measured in 16 previously untreated patients (group A) affected by polymyalgia rheumatica giant cell arteritis (PMR-GCA), both before, during, and after 45 days of steroid therapy, and its course was compared with the behavior of some acute-phase reactants such as erythrocyte sedimentation rate (ESR), fibrinogen (Fng), and prealbumin (Preal). No difference was detected between the baseline Fn levels found in patients and those registered in a control group composed of 15 sex- and age-matched healthy subjects; no correlation was found with the other acute-phase parameters considered, and no significant variation of plasma Fn levels was registered as a result of the steroid therapy administered. On the contrary, all the other parameters revealed a good degree of correlation and tended progressively and homogeneously towards normalization as a result of the therapy administered. Plasma Fn was also measured in another group of 16 PMR-GCA patients (group B), all of whom had pathological retinal fluoroangiographic findings, and its levels were compared with those of the von Willebrand factor antigen (vWfAg), a biochemical index of vascular damage. While the levels of Fn continued to be the same as those detected in the control group, the values of vWfAg registered in group B proved to be significantly different from those found in another homogeneous control group of 25 healthy subjects. Finally, no correlation could be detected between Fn and vWfAg, and neither of them showed any significant correlation with the ESR.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Reaction↗
PubMedDate not supplied

Behavior of prealbumin in the acute phase of polymyalgia rheumatica treated with 6-methylprednisolone.

Serum levels of prealbumin, fibronectin, fibrinogen, alpha 1-acid glycoprotein, C-reactive protein, immunoglobulins, and white blood cell count were prospectively studied in 33 patients affected by polymyalgia rheumatica during the first 45 days of treatment with 6-methylprednisolone. Almost all parameters considered, except for fibronectin and IgM, settled within the normal range fairly quickly, while prealbumin showed a specular course compared with the other reactants. This behavior reflected the improvement of clinical symptoms registered in all patients after steroid treatment. Finally, the genesis of the low baseline prealbumin levels found in polymyalgia rheumatica/giant cell arteritis and their behavior during treatment are discussed.

Aged↗