Biomedical subjects

F Nardi

Publications and source records attributed to F Nardi.

At least 37 records · Page 2Linked to original sources

PubMed2001

Sperm ultrastructure and spermiogenesis in the relic species Tricholepidion gertschi Wygodzinsky (Insecta, Zygentoma).

The silverfish Tricholepidion gertschi is of interest in that it is the most basal representative of Zygentoma. An ultrastructural study of its spermiogenesis was performed to find out whether there are traits which resemble those of other, more advanced insects. This was found to be the case; spermiogenesis can be considered to be of a common insectan type, leading to the formation of elongated sperm cells with acrosome, nucleus, neck region and a tail with axoneme and two mitochondrial derivatives. Total cell length, 50 microm, is short for an insect. There are some specializations, which probably represent autapomorphies. The acrosome has a posterior canal or cleft that makes a U-turn. The centriole adjunct forms a prominent post-nuclear ring surrounding the centriole and have a posterior extension, and further originates nine intertubular fibers with a longitudinal periodicity and two accessory bodies. The mitochondrial derivatives have five rows of regularly spaced cristae within a crystalline matrix. The axoneme has accessory tubules consisting of 16 protofilaments, formed at the B-tubules of the doublets and placed at some distance from them in the posterior part of the sperm tail.

Animals↗

PubMed2001

Binucleate and biflagellate spermatozoa in Tricholepidion gertschi Wygodzynsky (Insecta, Zygentoma).

The phenomenon of sperm pairing is known from some species of the apterygotan insect order Zygentoma, and has been described as the close apposition of two sperm cells. When released from the testes, they are single cells; pairing taking place in the deferent ducts. In a study of the relic species Tricholepidion gertschi, Zygentoma, sperm pairing was found to be due to a true fusion of two partners along their entire sperm head regions. The spermatozoon thus formed has two acrosomes, two nuclei and two separate sperm tails. The biflagellate spermatozoon swims with coordinated movements of its two flagella only when the two flagella lie close together but is totally uncoordinated when separate. The spermatozoon is about 50 microm long, thus much shorter than those of related apterygotan species. The mechanism of sperm cell fusion is unclear, although it appears that a 55-nm wide layer of electron dense substance, here termed the peripheral lamina, may play a role in delimiting the extent of sperm fusion.

Acrosome↗

PubMed2001

The complete mitochondrial DNA sequence of the basal hexapod Tetrodontophora bielanensis: evidence for heteroplasmy and tRNA translocations.

We present the complete 15,455-nt mitochondrial DNA sequence of the springtail Tetrodontophora bielanensis (Arthropoda, Hexapoda, Collembola). The gene content is typical of most metazoans, with 13 protein-coding genes (PCGs), 2 genes encoding for ribosomal RNA subunits, and 22 tRNA genes. The nucleotide sequence shows the well-known A+T bias typical of insect mtDNA; its A+T content is lower (72.7%) than that observed in other insect species, but still higher than that in other arthropodan taxa. The bias appears to be uniform across the whole molecule, unlike other insect taxa, which show increased A+T content in the so-called A+T-rich region. However, the bias is slightly higher in the third codon positions of the PCGs (81.4%). Anomalous initiation codons have been observed in the nad2 and the cox1 genes. In the latter, the ATTTAA hexanucleotide is suggested to be involved in the initiation signaling. All tRNAs could be folded into the typical cloverleaf secondary structure, but the tRNA for cysteine appears to be missing the DHU arm. Long tandemly repeated regions (193 nt) were found in the A+T-rich region, which in turn was shown to have the possibility of forming a complex array of secondary structures. One of these structures encompassed the junction between the repeats. The A+T-rich region was also interesting in that it showed heteroplasmy in the number of repeats. Three haplotypes were found, possessing 2, 3, and 4 identical repeats, respectively. The order of protein coding and rRNA genes in the molecule was determined and was identical to that of all insects studied so far. However, two tRNA translocations were found which were unprecedented among Arthropoda. These involved the trnQ, which was found between the rrnS and the A+T-rich region, and the trnS(ucn), which was located between trnM and trnI. A preliminary phylogenetic analysis based on the amino acid sequence of the PCGs failed to find support for the monophyly of Hexapoda.

Animals↗

PubMed2001

Isolated oropharyngeal Kaposi's sarcoma in non AIDS patient: differences and similarities with spindle-cell haemangioendothelioma.

Vascular tumours rarely affect the oropharynx and overall they can represent a diagnostic challenge since their clinico-histopathological patterns are not always clear. This case report, of an isolated pharyngeal vascular proliferation, allowed the authors to analyse the similarities and differences between Kaposi's sarcoma and spindle-cell haemangioendothelioma. Moreover, it emphasizes the importance of diagnostic tools, such as the human herpesvirus 8 (HHV8) marker, that sometimes may represent the only reliable test for clearly establishing the diagnosis.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Androgen deprivation, estrogen treatment and vascular function in male rat aorta.

The beneficial effects of estrogen on arterial function in women are well established, whereas studies concerning the vascular role of androgens have produced conflicting results. In the present study, we examined the effects of androgen deprivation and of estrogen treatment on vascular responses in male rats. Vascular reactivity was studied in aortic rings excised from intact and castrated rats, which had been implanted with capsules containing either 17beta-estradiol (E2) or its vehicle for 5 days. Contractile responses to noradrenaline were potentiated by castration and by E2 treatment. Concentration-response curves for N-methyl-L-arginine and superoxide dismutase indicated that the tone-related release of NO increased in tissues from castrated, compared with intact rats, but was not affected by E2 treatment. Endothelium-dependent relaxation elicited by carbachol and histamine were not altered by castration and were attenuated by E2 in preparations from intact, but not from castrated rats. Moreover, aortic prostacyclin release dropped by about 40% after E2 treatment in tissues from both intact and castrated animals. Similarly, smooth muscle sensitivity to NO significantly decreased following castration and E2 treatment, as assessed by responses to sodium nitroprusside. Finally, no differences among groups were detected in platelet thromboxane A2 production. Thus, vascular responses in male rats were not improved by androgen deprivation alone or by E2 treatment, whose effects differed in the presence or absence of androgens. These findings provide evidence for the gender specificity of the vascular effects of estrogen and may be consistent with a beneficial role of physiologic levels of male sex hormones in arterial function.

Androgens↗

PubMed2000

Diabetes influences the effect of 17beta-estradiol on mechanical responses of rat urethra and detrusor strips.

Estrogen deficiency is one of the factors involved in the stress incontinence in postmenopausal women, and estrogens have been used clinically in the treatment of urinary disorders during menopause. Sex hormones seem to be also involved in the diabetic changes of urinary bladder and urethra, because ovariectomy causes an increase in the micturition of streptozotocin-diabetic rats. In the present study diabetic and healthy female rats were used to investigate the effect of 17beta-estradiol on mechanical contractions to norepinephrine and to KCI and relaxations to ATP on isolated proximal urethral preparations as well as on contractions to ACh, ATP and KCl on detrusor smooth muscle strips. The data were compared with those obtained in OVX animals, with or without estradiol replacement. The present study showed that ovariectomy decreased the responses to ATP, NE and KCl in urethral preparations, and responses to ATP, ACh and KCl in bladder strips from both healthy and diabetic rats. Diabetes appeared to potentiate the effect of ovariectomy in both tissues. Estrogen replacement was able to recover functional responses in urethras of healthy rats. In diabetic rats, this treatment partially restored ATP-induced responses in both tissues, almost completely restored those to NE in urethra and those to ACh in bladder. This study clearly indicated that abnormalities of urethra and bladder function caused by ovariectomy can be restored by estrogen treatment also in diabetic animals, at least at an early stage of disease.

Adenosine Triphosphate↗

PubMed2000

The cisproline(i - 1)-aromatic(i) interaction: folding of the Ala-cisPro-Tyr peptide characterized by NMR and theoretical approaches.

Cisproline(i - 1)-aromatic(i) interactions have been detected in several short peptides in aqueous solution by analysis of anomalous chemical shifts measured by 1H-NMR spectroscopy. This formation of local structure is of importance for protein folding and binding properties. To obtain an atomic-detail characterisation of the cisproline(i - 1)-aromatic(i) interaction in terms of structure, energetics and dynamics, we studied the minimal peptide unit, blocked Ala-cisPro-Tyr, using computational and experimental techniques. Structural database analyses and a systematic search revealed two groups of conformations displaying a cisproline(i - 1)-aromatic(i) interaction. These conformations were taken as seeds for molecular dynamics simulations in explicit solvent at 278 K. During a total of 33.6 ns of simulation, all the 'folded' conformations and some 'unfolded' states were sampled. 1H- and 13C-chemical shifts and 3J-coupling constants were measured for the Ala-Pro-Tyr peptide. Excellent agreement was found between all the measured and computed NMR properties, showing the good quality of the force field. We find that under the experimental and simulation conditions, the Ala-cisPro-Tyr peptide is folded 90% of the time and displays two types of folded conformation which we denote 'a' and 'b'. The type a conformations are twice as populated as the type b conformations. The former have the tyrosine ring interacting with the alanine alpha proton and are enthalpically stabilised. The latter have the aromatic ring interacting with the proline side chain and are entropically stabilised. The combined and complementary use of computational and experimental techniques permitted derivation of a detailed scenario of the 'folding' of this peptide.

Amino Acids↗

PubMed1999

Human herpesvirus-8 in lymphomatous and nonlymphomatous body cavity effusions developing in Kaposi's sarcoma and multicentric Castleman's disease.

Human herpesvirus-8 (HHV-8) has been associated with Kaposi's sarcoma, multicentric Castleman's disease and primary effusion lymphoma. Kaposi's sarcoma and multicentric Castleman's disease patients may develop body cavity effusions that, unlike primary effusion lymphoma, are poorly characterized. To better define these effusions, pleural and peritoneal fluids derived from 12 human immunodeficiency virus-seropositive and one seronegative patients affected by Kaposi's sarcoma or multicentric Castleman's disease were analyzed by a combination of morphologic, immunophenotypic, and DNA analyses, including polymerase chain reaction amplification of HHV-8, Epstein-Barr virus, and immunoglobulin heavy-chain (IgH) gene sequences. In addition, HHV-8 serologic status was assessed by using an immunofluorescence assay. All patients were adult men with high antibody titers to HHV-8; 11 of the 13 patients were homosexual/bisexual. Effusions revealed monocyte/macrophage-rich infiltration (10 patients) or large-cell lymphoma with CD45(+)/non-T/non-B phenotype (three of 13 patients); polymerase chain reaction analysis showed the presence of HHV-8 sequences (nine of 13 patients), germline IgH (seven of 12 patients) or clonal IgH rearrangements (four of 12 patients), and rarely Epstein-Barr virus sequences (two of 12 patients). In the setting of HHV-8 infection, two effusion types may occur. One fulfills the criteria for HHV-8-positive PEL (lymphoma-morphology, HHV-8-DNA(+), IgH rearrangement). The other seems more reminiscent of an HHV-8-associated nonneoplastic process (monocyte-macrophage morphology, HHV-8-DNA(+/-), germline IgH). Interestingly, a single case of the latter effusion type harbored a B-cell monoclonal proliferation, which suggests the hypothesis that a prelymphomatous effusion may precede overt body cavity lymphoma.

Adult↗

PubMed1999

Microsatellite instability in thyroid tumours and tumour-like lesions.

Fifty-one thyroid tumours and tumour-like lesions were analysed for instability at ten dinucleotide microsatellite loci and at two coding mononucleotide repeats within the transforming growth factor beta (TGF-beta) type II receptor (TbetaRII) and insulin-like growth factor II (IGF-II) receptor (IGFIIR) genes respectively. Microsatellite instability (MI) was detected in 11 out of 51 cases (21.5%), including six (11.7%) with MI at one or two loci and five (9.8%) with MI at three or more loci (RER+ phenotype). No mutations in the TbetaRII and IGFIIR repeats were observed. The overall frequency of MI did not significantly vary in relation to age, gender, benign versus malignant status and tumour size. However, widespread MI was significantly more frequent in follicular adenomas and carcinomas than in papillary and Hürthle cell tumours: three out of nine tumours of follicular type (33.3%) resulted in replication error positive (RER+), versus 1 out of 29 papillary carcinomas (3.4%, P = 0.01), and zero out of eight Hürthle cell neoplasms. Regional lymph node metastases were present in five MI-negative primary cancers and resulted in MI-positive in two cases.

Adenocarcinoma, Follicular↗

PubMed1999

Cytospray fixation of frozen intraoperative sections.

Preservation of cellular morphologic features is well known to be a limit of intraoperative frozen sections. Various techniques have been proposed to improve tissue details, the most common being ethanol immersion of cryostatic slide. We tested fixation with spray formulation for cytology smears on intraoperative frozen section from different organs to obtain a quick alcoholic fixation and a ready-to-use method. Our results of comparative study showed that cytospray fixation of frozen sections provide a significant improvement of cellular details, that it is quick, simple, economic, and that it does not require preorganization.

Aerosols↗

PubMed1998

Familial pleural malignant mesothelioma: clustering in three sisters and one cousin.

Malignant mesothelioma is associated with asbestos, yet its occurrence in genetically-related individuals suggests a role of host predisposition. We have identified a cluster of pleural malignant mesothelioma in three sisters and one cousin (male). The women had worked in the same confectionery shop as pastry cooks and/or pastry shop assistants; the use of an asbestos-insulated oven was the putative source of exposure. The man had occupational exposure as a heating system installation worker. The family history reported malignant cancers in first-degree (larynx, brother; pleura and lung, mother), second-degree (lung, aunt and uncle) and third-degree (lung, cousin) relatives. The study reveals the potential existence of the mesothelioma risk among pastry cooks and highlights the fact that inherited factors may be involved in the development of this tumour.

Aged↗

PubMed1998

Cyclin D1 and Cyclin E expression in malignant thyroid cells and in human thyroid carcinomas.

Evidence of the involvement of cyclin gene alterations in human cancer is growing. In this study, we sought to determine the pattern of expression of cyclin D1 and cyclin E in normal and malignant thyroid cells. Quiescent rat thyroid cells in culture, induced to synthesize DNA by thyrotropin (TSH), expressed cyclin D1 gene after 6 hr and cyclin E gene with a peak at 18 hr from the stimulus; K-ras-transformed rat thyroid cells, which grew without addition of hormones necessary for normal cell proliferation, expressed elevated levels of cyclin D1 and cyclin E, compared with normal differentiated thyroid cells. Human benign and malignant thyroid tumors and their relative normal tissues were then analyzed. Neither major genetic alterations nor amplifications for cyclin D1 and cyclin E genes were found by Southern blot analysis in genomic DNAs extracted from all types of thyroid tumors. Moreover, statistical analyses of densitometric values from Northern blots did not show increased levels of cyclin D1 and E mRNAs in the tumor samples, compared with normal thyroid. Immunohistochemical analyses of formalin-fixed paraffin-embedded sections of tissues with specific antibodies revealed a prevalent cytoplasmic cyclin E staining in the thyroid tissues analyzed. Cyclin D1, instead, was present in the cytoplasm of normal thyroids and adenomas, but in 31% of thyroid papillary carcinomas analysed, it was overexpressed, with a localization in the nucleus. Our in vivo observations suggest that unlike cyclin E, elevated nuclear cyclin D1 expression defines a subset of thyroid papillary carcinomas, and might be a contributory factor to thyroid tumorigenesis.

Animals↗

PubMed1998

Portal thrombosis. A rare complication of laparoscopic splenectomy.

Portal thrombosis is a rare complication of splenectomy. We performed 12 laparoscopic splenectomies and observed this complication only in one patient with idiopathic thrombocytopenia (ITP). The right branch of the portal vein presented a partial thrombosis, while the left branch was completely obstructed by thrombi. Abdominal ultrasonography and an ultrasound doppler exam allowed us to diagnose this event and a retrograde angiography performed afterward confirmed our diagnosis. A 48-h intravenous heparin treatment was promptly begun, followed by anticoagulant drugs (dicumarol). The patient was dismissed 5 days afterward, presenting a steady-state ultrasound doppler pattern and a complete normalization of liver parameters. An ultrasound doppler exam performed 1 month after anticoagulant therapy showed a complete resolution of portal thrombosis. We believe that early diagnosis of this rare complication, prompt beginning of anticoagulant therapy, and care in surgical procedures may reduce patient life-threatening risks and assure complete remission.

Adult↗

PubMed1998

Absence of HHV-8 DNA sequences in malignant mesothelioma.

Human herpesvirus 8 (HHV-8) associated primary effusion lymphomas arise and grow in the body cavities as effusions, but it is not known whether the lining of body cavities and mesothelium derived malignancies are potential targets of HHV-8 infection. We examined a series of 13 diffuse malignant mesotheliomas and four mesothelial cell rich effusion samples of non-neoplastic aetiology from non-immunodepressed patients using the polymerase chain reaction to detect HHV-8 specific sequences. HHV-8 amplification products were absent in diffuse malignant mesotheliomas and in non-neoplastic effusions samples. These results suggest that HHV-8 has a selective tropism among body cavity based tumours, being confined to primary effusion lymphomas.

Adult↗

PubMed1998

Long-term changes in nodular goiter: a 5-year prospective randomized trial of levothyroxine suppressive therapy for benign cold thyroid nodules.

We studied for 5 yr a homogeneous group of 83 patients randomly assigned to a levothyroxine (L-T4) suppressive therapy or to a control group to evaluate changes in nodule or thyroid size, appearance of new nodules, and correlations with clinical parameters. In the control group, mean nodule volume increased significantly after 5 yr (2.12 +/- 1.46 vs. 1.46 +/- 0.77 mL), whereas in the treatment group it decreased, although not significantly (1.45 +/- 1.17 mL vs. 1.53 +/- 0.61 mL). Baseline nodule volume was not different in the two groups, but a significant difference was observed at 5 yr. After 5 yr, sonograms detected 12 new nodules in the control group (28.5%) and 3 (7.5%) in the treatment group. Nodule shrinkage was more frequent in patients with complete TSH suppression, but no correlation was found with other parameters. A significant increase in thyroid size was observed in the control group. In conclusion, long term TSH suppression induced volume reduction in only a subgroup of thyroid nodules, but effectively prevented the appearance of new lesions and increases in nodule and thyroid volume. As the changes in the natural history of nodular goiter are related to prolonged TSH suppression, which can induce unfavorable side-effects, L-T4 suppressive therapy should be reserved for small nodules in younger patients.

Adult↗

PubMed1998

Radiology of adjustable silicone gastric banding for morbid obesity.

We reviewed the radiological findings in 45 morbidly obese patients (weight range 80-129 kg; mean 95.7 kg) after gastric restriction surgery with adjustable silicone gastric banding (ASBG) according to the Kuzmak technique. Radiographic studies of the stomach were performed before, and at 4 and 12 months after surgery; symptomatic patients underwent additional studies when needed. Patients were evaluated using both liquid barium and a solid opaque meal to assess post-operative gastric morphology as well as emptying time of the proximal gastric pouch. 27 patients had a normal clinical course. Variation of the calibre of the silicone band under radiographic guidance was required in 12 of these patients, based on dilatation of the proximal pouch, variation of the stomal calibre from operative values, or an emptying time longer than 30 min. All these problems disappeared after the adjustment manoeuvres. 18 patients had complications, of which five had stomal stenosis which could not be managed through simple deflation of the band; two had posterior bending and dilatation of the proximal pouch; four had gastritis and oesophagitis; six had infection of the inflatable reservoir; one had cranial displacement of the band, and two had migration of the band into the stomach. Removal of the gastric band was necessary in 11 cases, and removal of the reservoir alone had to be performed in three additional patients. Radiology plays an important role in evaluating complications after gastric restriction surgery. Knowing the variety of findings enables accurate treatment planning and follow-up of these patients.

Adolescent↗

PubMed1998

Loss of phosphoserine polar group asymmetry and inhibition of cholesterol transport in Jurkat cells treated with cholesterylphosphoserine.

Cholesterylphosphoserine (CPHS) is a synthetic ester of cholesterol showing immunosuppressive activity. In the present study, we have used the T cell line Jurkat to investigate its mechanism of action. CPHS incorporates into cells reaching a molar ratio of 0.23 and 3.9 with the total phospholipid and cholesterol content, without inducing necrosis or apoptosis. CPHS incorporation elicits a dose-dependent binding of fluorescein isothiocyanate-labeled annexin V, suggesting that the steroid distributes in the external leaflet of plasma membrane exposing the phosphoserine group to the external cell environment and inserting the steroid ring into the phospholipid bilayer. In agreement with a preferential steroid association with sphingolipids, CPHS is included in a Triton X-100-insoluble complex when mixed with sphingomyelin and cholesterol. CPHS incorporation inhibits the esterification of low density lipoprotein (LDL)-derived cholesterol, producing a minor influence on the endogenous synthesis of cholesterol and on the acyl-CoA:cholesterol acyltransferase activity. In this effect, CPHS is as potent as progesterone (IC50 of 3.5 microM). It is concluded that the insertion of cholesterylphosphoserine (CPHS) in the Jurkat plasma membrane neutralizes the asymmetric distribution of the phosphoserine group and inhibits the movement of cholesterol to the endoplasmic reticulum. As CPHS is a negatively charged steroid, this last effect may be linked to the perturbation of sphingolipid/cholesterol-based microdomains, proposed to play a role in cholesterol trafficking.

Adjuvants, Immunologic↗

PubMed1997

Human malignant thyroid tumors displayed reduced levels of transforming growth factor beta receptor type II messenger RNA and protein.

Transforming growth factor beta (TGF-beta) is a physiological regulator of thyroid epithelial cell growth and differentiation. This factor signals through a heteromeric complex composed of type I (TGF-beta receptor type I) and type II [TGF-beta receptor type II (TbetaRII)] receptors. Loss of TbetaRII expression has been related to resistance to TGF-beta inhibition of cell proliferation. In the present work, we analyzed the TbetaRII expression in a series of human thyroid tumors, from benign lesions (adenomas) to neoplastic lesions of increasing aggressiveness (papillary and follicular carcinomas) up to the extremely aggressive anaplastic tumors. Results obtained indicated a clear reduced expression of TbetaRII mRNA only in the group of thyroid carcinomas when compared with their relative normal tissues. Immunohistochemical analyses with specific anti-TbetaRII antibodies confirm these observations. These data indicate that loss of expression of TbetaRII can contribute to thyroid cancer progression, inducing cancer cells to escape the growth-inhibitory effect of TGF-beta.

Adenocarcinoma, Follicular↗