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Biomedical subjects

M Marchini

Publications and source records attributed to M Marchini.

At least 91 records · Page 5Linked to original sources
PubMed1982

Why inclusion bodies do assume different locations in thalassaemic erythrocytes.

The reported scanning (SEM), transmission (TS), and freeze-etching (FE) electron microscopic studies have agreed in confirming that in thalassaemic erythrocytes, previously incubated with brilliant cresyl blue (BCB), the unpaired alpha chains precipitate in the central portions of the cell whereas excess beta chains locate in the submembranous regions. This is due to the fact that beta chains, possessing two thiols instead of only one (as in alpha chains), are more liable to bind to similar groups contained in the inner red cell leaflet. Less soluble alpha chains tend to form inter-chain bridges and thus precipitate centrally. SEM observations have given evidence that on the surface of the affected red cells denaturated alpha chains give rise to large and shallow invaginations whereas denatured beta chains lead to diffuse wrinkled appearance. The causes of the different SEM aspects have been suggested.

Adolescent↗
PubMed1982

Pseudo-elastica in alcoholic hepatic fibrosis: histochemical and ultrastructural aspects.

During the early phases of alcoholic hepatic fibrosis, histochemical studies show positivity to both specific elastin and the specific collagen stains at the level of the centrolobular vein, the portal triad and portacaval anastomosis. Ultrastructural investigation in the portacaval anastomosis demonstrates the presence of collagen fibrils and afibrillar material. Treatment with tannic acid increases the contrast of these structures. The possible correlations between histochemical and ultrastructural findings are discussed.

Collagen↗
PubMed1980

[Distribution of proteoglycans in the sclera].

The Authors have studied, with histochemical methods, the manner of proteoglycans distribution in superficial and deep layers of the sclera, which are characterized by structural differences regarding collagen. The pictures, on one hand, are in agreement with biochemical data which indicate the presence of dermatan-sulfate, chondroitin-sulfate and hyaluronic acid, on the other hand, show a marked glycosaminoglycans distribution in the deep layers and a lessening of their distribution relative to the superficiality of the layers. Furthermore alcianophilic particles are visualized at the electron microscope. In the superficial layers such particles are in direct relation, often periodically, with the collagen fibrils, while in the deep layers particles without this direct relationship are also observable. The Authors point out a topographic coincidence between variations regarding the proteoglycans distribution and variations regarding collagen. Moreover, the obtained pictures suggest the existence of a particular proteoglycans-collagen interaction corresponding to the deep layers where fibrillogenesis occurs.

Animals↗
PubMed1980

[Ultrastructure of collagen fibers in the sclera].

The Authors have studied the microfibrillar packing of the scleral collagen fibrils on thin sections of samples treated with a dissociant agent and on replicas of freeze-fractured fibrils. The only difference in observing the fibrils between the external and internal layers is relative to the diameter, evidencing in general, lower dimensions in the latter. The microfibrillar packing is characterized by a lightly spiralized or wavy running of filamentous subunits and the same is evident in fibrils of different diameter. The ultrastructural pictures are similar to those obtained in the other tissues, such as tendons, fibrous cartilages, fibrous capsules of parenchymatous organs and ligaments, in which the collagen is predominantly type I, like in the sclera.

Animals↗
PubMed1980

[Study of rat tail tendon by x-ray diffraction and freeze-etching technics].

Rat tail tendon collagen processed according to different fixation and cryoprotection treatments has been examined by small angle X-ray diffraction and freeze-etching techniques. The results show some differences in the axial period and in the degree of disorder of the molecular packing as a function of the applied treatment.

Animals↗
PubMed1979

Proteoglycans and their relationship with the other components of the rabbit aorta wall observed in two different experimental conditions.

An electron microscopic study of the aorta wall of rabbit was carried out employing electron microscopic histochemical methods aimed at examining the distribution of proteoglycans and their correlation with the other structural components of the aorta wall. The ultrastructural evidence of the proteoglycans has been obtained by treating the arterial wall with alcian blue stain and supporting this staining procedure with control enzyme treatments. Moreover, in order to attain a better interpretation of the ultrastructural findings, the arterial wall has been studied under 2 different experimental conditions, the 1st one being represented by an accentuated contraction of the vase's wall, following immersion in the fixator, the other one by an extreme distension of the wall, reached prior to fixation, subjecting the tissue to its tension limit of 700 dyn/mm2. This type of electron microscopic visualization of the proteoglycans following alcian blue treatment leads on to think that at least 2 distinct macromolecular entities of proteoglycans exist, each one having an unusual relationship with the other components of the arterial wall. Different site and types of interaction are to be noted for each of the 2 distinct ultrastructural proteoglycans entities.

Animals↗
PubMed1979

Ultrastructural observations on collagen and proteoglycans in the annulus fibrosus of the intervertebral disc.

Replicas of freeze-fractured collagen fibrils of peripheral and central parts of the annulus fibrosus of bovine intervertebral discs show microfibrils which run either arranged in parallel or in a helix with an inclination-angle ranging from 4 degrees to 8 degrees. According to results of freeze-fracutred tissues, thin sections of specimens treated with 4M guanidinium chloride show collagen fibrils with a parallel or a slightly wavy microfibrillar packing. Thin sections of specimens treated with alcian blue diluted in MgCl2 critical electrolyte solutions reveal interfibrillar proteoglycan particles with a filamentous shape in the peripheral zones of the annulus fibrosus and a predominant leaf-like appearance in the inner ones. These observations are discussed with reference to previous data concerning the variation in composition from the peripheral to the inner parts of the annulus fibrosus.

Animals↗
PubMedDate not supplied

Effect of urea and detergents on the ability of human spermatozoa to penetrate zona-free hamster oocytes.

Washing of human spermatozoa with either BWW alone or with the same buffer containing 0.1 M urea, 0.005% SDS or 0.001% NP40 affected the penetration ability of the gametes into zona-free hamster oocytes to various degrees. In contrast, human spermatozoa washed with BWW buffer containing 0.3 M urea had an increased ability to fuse with the heterologous oocytes when compared to controls capacitated with BWW/BSA. Moreover, the presence or absence of BSA in the insemination medium did not further modify this enhanced penetration pattern. The BWW, BWW/0.1 M urea and BWW/SDS treatments apparently mimicked some of the in vitro capacitation properties of albumin-containing media; the BWW/0.3 M urea treatment overpowered the capacitation and acrosomal reaction extent obtained with BWW+BSA. In all samples the motility of the spermatozoa washed with BWW buffer alone or containing various additives (but no albumin) was significantly decreased if compared to the motility of semen samples washed with albumin containing media. However, each sperm sample behaved differently when exposed to a given buffer.

Animals↗
PubMedDate not supplied

Removal of sperm-coat from human spermatozoa by interaction with cervical mucus or a capacitating medium.

Human spermatozoa were labelled with cationized ferritin and their interaction with cervical mucus or a capacitating medium enriched with 3% bovine serum albumin (BSA) was investigated by transmission electron microscopy. It was found that the sperm-coat was removed from the surface of spermatozoa after incubation in the BSA-enriched capacitating medium, as well as after crossing a column filled with cervical mucus. These results suggest that both media have a quantitatively similar action in removing the sperm-coat.

Cervix Mucus↗
PubMedDate not supplied

Etiology of severe asthenozoospermia and fertility prognosis. A screening of 5216 semen analyses.

A review of n = 5216 semen analyses performed in our two Clinics from January 1986 to December 1989 allowed to identify n = 35 patients whose sperm had constantly very low motility (less than 5% progressive motile gametes in three subsequent analyses; necrozoospermia cases were excluded from this study). This apparently rare but severe anomaly was found to be associated not only with ultrastructural anomalies (n = 18), but also with positive seminal bacteriology (n = 8) or the presence of antisperm antibodies (n = 2). In eight cases the cause(s) for this constant asthenozoospermia remained obscure. The fertility potential of the men affected was followed-up and is discussed in relation to their anamnesis, physical exam and seminal characteristics.

Adult↗
PubMedDate not supplied

Gonads and genital ducts in a case of male pseudohermaphroditism.

We describe a patient with a 46,XY karyotype, ambiguous external genitalia and partial 17a-hydroxylase deficiency in whom we performed a light microscopic study of the gonads and genital ducts. The right and left testes and epididymides were hypoplastic whereas the right vas deferens was normal, the left one was atretic and a left infundibular remnant was also present, which could be due to a concomitant deficiency in testicular secretions in the early stages of embryonic development or to the possibility of receptor insensitivity for testicular hormones or to a concomitant gonadal dysgenesis.

17-Ketosteroids↗
PubMedDate not supplied

Risk factors for unexplained dyspermia in infertile men: a case-control study.

This study was conducted to analyze risk factors for dyspermia in infertile subjects in a population of men attending outpatient services for infertility in Milan, Northern Italy. Between September 1989 and November 1990 we conducted a case-control study on risk factors for dyspermia. Cases included infertile men with a diagnosis of unexplained dyspermia consecutively observed for the first time during the study period at the Outpatient Service for Infertility of the First Obstetric and Gynecologic Clinic of the University of Milan. Specific work-up was done to exclude the major known or potential causes of dyspermia and infertility in patients and their partners. Two control groups were selected. The first included normospermic men of infertile couples with negative work-up for any disease that might affect fertility, observed in the same outpatient service where cases had been identified. The second control group included fertile men of unknown semen quality who were the partners of women who gave birth at term (> 37 w gestation) to health infants in randomly selected days at the same clinic. In comparison with those who have never smoked, current smokers were at increased risk of dyspermia versus both normospermic men of infertile couples and fertile men of unknown semen quality, and the risk increased with number of cigarettes smoked per day and duration of smoking. The risk of dyspermia increased with the number of cups of coffee drunk per day compared with men drinking no or one cup per day. Likewise, alcohol drinkers were at increased risk and the risk increased with number of drinks/d.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMedDate not supplied

Simultaneous intra- and extrauterine pregnancy after multiple ovulation induction.

Superovulation was induced by combined treatment with a GnRH analog, hMG and hCG in a 31 years old nulligravida with a diagnosis of unexplained infertility. She developed a mild hyperstimulation syndrome for which she received conservative treatment in hospital, and she was discharged only after we demonstrated a gestation sac in utero with evident fetal heart beat and beta hCG assays were positive. One week later the patient was readmitted urgently with acute abdominal pain. Laparoscopy revealed a left tubal pregnancy with corpus luteum on the right ovary and free blood in the pouch of Douglas. Salpingotomy was therefore performed with dilatation and curettage of the uterine cavity. Histological examination confirmed the presence of contemporary intra- and extrauterine pregnancy. Based on this first communication, a high index of clinical suspicion for an extrauterine pregnancy is warranted in all patients undergoing superovulation even after a pregnancy in utero has been demonstrated.

Adult↗
PubMedDate not supplied

Serum Ca-125 concentrations in endometriosis.

Serum Ca-125 levels were measured in 154 patients undergoing laparoscopy or laparotomy for infertility and/or pelvic pain. Pelvic endometriosis at various stages was observed in 102 of the patients, and 52 had a visually normal pelvis and served as a control group. We found a significantly higher mean serum Ca-125 concentration in the patients with stages III and IV endometriosis compared with the controls (P less than 0.001) whereas in the patients with stages I and II disease the mean antigen level was comparable to that of the control group. Considering its low sensitivity (14.7%) the usefulness of serum Ca-125 measurements as an initial diagnostic test for endometriosis is scanty. On the contrary, because of its elevated specificity (100%), this test may be useful in indicating early surgical exploration of the pelvis in cases of infertility and/or dysmenorrhea which are associated with high values of Ca-125.

Adult↗