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Biomedical subjects

G Bernasconi

Publications and source records attributed to G Bernasconi.

At least 19 recordsLinked to original sources
PubMed2000

Female-mediated differential sperm storage in a fly with complex spermathecae, Scatophaga stercoraria.

Multiple spermathecae potentially allow selective sperm use, provided that sperm from rival males are stored differentially, that is, in different proportions across storage compartments. In the yellow dung fly, Scatophaga stercoraria, females have three spermathecae arranged as a doublet and singlet. To test whether females store the sperm of rival males actively and differentially, we mated fixed male pairs to three females. After copulation, females were (1) dissected immediately before they could start laying a clutch of eggs, (2) left awake for 30 min but prevented from oviposition, or (3) anaesthetized with carbon dioxide for 30 min to interfere with the muscular control presumably required for sperm transport from the site of insemination to the spermathecae. For each female, we estimated the proportion of the second male's sperm stored in her spermathecae (S(2)value), using sperm length as a male marker. After copulation, the S(2)values in the singlet and doublet spermathecae differed significantly, indicating differential sperm storage during copulation. Postcopulatory treatment affected differential sperm storage significantly. Females dissected immediately had lower S(2)values in the doublet than in the singlet spermatheca, while females left awake showed the reverse pattern for the same two males. This reversal did not occur when females were treated with carbon dioxide. The results indicate differential storage of sperm from different males during copulation and that female muscular activity can affect storage and separation of competing ejaculates beyond copulation. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Cellular S-100 protein immunostaining in human dysfunctional temporomandibular joint discs.

S-100 protein was detected immunohistochemically in diseased human temporomandibular joint discs with different degrees of pathology, and the findings compared with those of normal discs. In normal discs, large nerve trunks in the posterior ligament were strongly stained by anti-S-100 antiserum; the very few chondrocyte-like cells sometimes showed faint staining, while no staining was observed in any fibrochondrocyte-like or fibroblast-like cell. In dysfunctional discs, S-100 protein immunostaining seemed to correlate with structural pathological findings. The discs showing an abnormal collagen arrangement or fragmentation of collagen fibres presented overall the same immunolabelling pattern as normal discs. In discs with fibrocartilaginous metaplasia and dystrophic cartilage formation, fibrochondrocyte cells showed a very strong immunoreaction for S-100 protein and fibroblast-like cells in some instances were also positive. These findings suggest that S-100 upregulation in disc cells can be considered an attempt at tissue repair by chondroid metaplasia following an injury in that it enables fibroblast-like cells and fibrochondrocytes to acquire a chondrogenic phenotype.

Adult↗
PubMed1999

Effect of queen phenotype and social environment on early queen mortality in incipient colonies of the fire ant, Solenopsis invicta.

In many ant species, including the fire ant Solenopsis invicta, queens can found their colonies alone or in associations of two or more. Colonies founded by associations produce a larger worker brood, have higher survival and mature earlier than colonies founded by solitary queens. However, cofoundresses almost invariably fight after the eclosion of the first workers. As a result, only one queen survives and monopolizes the colony's future reproductive output. Queen mortality also occurs before worker eclosion, but neither the causes (e.g. starvation, conflict), nor the factors (e.g. social environment) potentially affecting its occurrence, have been investigated. We analysed the effect of social environment and queen body mass on early mortality by keeping queens (1) solitarily, (2) within associations of four queens of the same initial mass, and (3) within associations of four queens of random initial mass. Mortality was higher for queens within associations than for solitary queens. Within associations of equally heavy queens, mortality significantly increased with the queens' body mass. In contrast, mortality of solitary queens did not significantly depend on body mass. Early mortality was significantly more frequent in associations of queens of random initial mass than in associations of equally heavy queens. Altogether these results demonstrate that queen phenotype differentially affects early queen mortality depending on the social environment, and suggest that reproductive competition rather than starvation is the main cause of mortality in multiple-queen associations. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Immunolocalization of gelatinase-A (matrix metalloproteinase-2) in damaged human temporomandibular joint discs.

The fibrous tissue of the articular disc of the dysfunctional temporomandibular joint undergoes deep and variable structural modifications. Here the concurrence of morphological changes and the expression of matrix metalloproteinase-2 (MMP-2) in damaged discs from individuals suffering joint dysfunction was investigated. Microscopic, ultrastructural and immunocytochemical investigations were made on variously damaged articular discs and on one control sample. Disaggregation of collagen fibres, an increase in cellular components and calcification of large areas of tissue were observed in the damaged discs. These modifications were accompanied by a positive immunoreaction pattern for MMP-2. Fibroblast-, chondroblast- and osteoblast-like cells displayed a positive cytoplasmic reaction. In samples displaying evidence of synovial hyperplasia, some cells of the synovial protrusions were MMP-2 immunoreactive. No MMP-2 staining was observed in the control sample. These findings demonstrate that structural modifications of the articular disc could be specific responses to changes in the function of the temporomandibular joint. Variations in extrinsic stimuli may activate intrinsic factors, such as MMPs, that induce structural modifications in the discal tissue.

Adult↗
PubMed1999

Cooperation among unrelated individuals: the ant foundress case.

Ant foundress associations are an example of cooperation among non-kin. Across a dozen genera, queens able to found a colony alone often join unrelated queens, thereby enhancing worker production and colony survivorship. The benefits of joining other queens vary with group size and ecological conditions. However, after the first workers mature, the queens fight until only one survives. The presence of cofoundresses, and their relative fighting ability, also affects the extent of cooperative investment before worker emergence. This reveals previously overlooked early conflicts among queens, which reduce the mutualistic benefits of cooperation.

Journal Article↗
PubMed1998

Intramuscular beta interferon for chronic hepatitis C: is it worth trying?

BACKGROUND AND AIMS: The intramuscular use of beta interferon has been tested in the treatment of chronic hepatitis C, but it did not prove effective when the schedule was 3 million units three times a week for six months. Since the lack of effectiveness of this treatment might be due to the low bioavailability of beta interferon when administered intramuscularly, we tested a higher dosage of the drug: 6 million units three times a week for twelve months. PATIENTS AND METHODS: Ninety-two patients were randomized to receive, intramuscularly, either 3 or 6 million units of natural human fibroblast beta interferon three times a week for 12 months. RESULTS: The short-term biochemical response was significantly more frequent in the group of patients who received the higher dosage of beta interferon: 21% vs 4.5% (p < 0.05). Nevertheless, a sustained biochemical response was obtained in only one patient (2%), who received the higher dosage of beta interferon. CONCLUSIONS: Since the better short-term response rate was obtained with the higher dosage of beta interferon, a further increase in the dosage might improve the short-term and, possibly, the long-term response to treatment. However, due to the high cost of beta interferon, this high-dose schedule would probably not be cost-effective in the treatment of chronic hepatitis C.

Adult↗
PubMed1997

Synovia hyperplasia and calcification in the human TMJ disk: a clinical, surgical, and histologic study.

The aim of the study was to investigate the morphologic modifications occurring in the synovial tissue after severe derangement of the articular structures with dislocation or perforation of the disks. Light microscopic, ultrastructural, and immunocytochemical investigations were performed on 10 disks. Arthroscopic examinations had documented adhesions between the diskal surfaces and the glenoid eminence or the condylar head in all the selected cases. Histologic examination showed a remarkable hyperplasia of the synovial tissue with the formation of prominent protrusions. An evident increase of type B (fibroblast-like) cells and the presence of cells with the ultrastructural and immunocytochemical characteristics of myofibroblasts were observed. Foci of mineral precipitates and large deposits of calcified tissue were present in the synovial villi in three samples. Our observations suggest that functional failure and morphologic lesions of the synovia may be caused by arthropathy.

Actins↗
PubMed1997

The articular disc surface in different functional conditions of the human temporo-mandibular joint.

The peripheral discal tissue and the surface covering layer have been studied in normal and in variously damaged human temporo-mandibular joint discs. In the normal disc the tissue consisted of dense bundles of fibers and rare fibrocytes. The surface of the disc was covered by a regular basophilic and electron-dense layer. These morphological characteristics persisted also in some pathological discs in which fibrous derangements had already occurred in the deep parts. In very deformed and damaged discs associated with serious functional anomalies, the superficial discal tissue consisted of rare fibers dispersed in a loose ground substance and of an increased number of cells. The superficial coating was formed by an irregular dense lamina and aggregates of various materials containing cellular debris, vesicles, filaments and amorphous components. These deposits are probably due to degeneration processes of discal tissue. This investigation suggests that the superficial discal tissue and the covering layer are together involved in maintaining the functional properties of the articular surfaces. Their structural modification in severe functional anomalies leads to failure in the maintenance of nonadherence conditions and to deterioration of the functional defect.

Actin Cytoskeleton↗
PubMed1996

Conversion of recent onset atrial fibrillation with single loading oral dose of propafenone: is in-hospital admission absolutely necessary?

A population of 283 patients with recent onset (< 72 hours) AF, without heart failure, who received a single 450- or 600-mg oral dose of propafenone, or digoxin 1 mg, or placebo for conversion to sinus rhythm (SR), was studied to determine whether a routine admission to the hospital for drug administration is justified. Previous bradyarrhythmias or sick sinus syndrome (SSS), and concomitant use of antiarrhythmic drugs were exclusion criteria. None of the 283 patients studied experienced VT or VF and none of them needed implantation of a temporary pacemaker. Periods of atrial tachyarrhythmias with regularization of atrial waves and 1:1 AV conduction were observed in only two cases, both receiving placebo. No predictor of proarrhythmia was found among the clinical variables considered (age, etiology, arrhythmia duration, atrial dimension, and blood potassium). No serious hemodynamic adverse effects were noted in either group. The rates of conversion to SR after 4 hours were: 80 (57%) of 141 patients who received propafenone and 35 (25%) of 142 patients who received digoxin or placebo (P < 0.001). Acute oral treatment with propafenone is simple and effective for the conversion of recent onset AF to SR in patients without clinical signs of heart failure. The routine admission of these patients to the hospital is not necessary. Home-based administration of oral propafenone to a selected group of patients could significantly increase the cost effectiveness of this treatment.

Administration, Oral↗
PubMed1996

Interictal mood and personality disorders in temporal lobe epilepsy and juvenile myoclonic epilepsy.

BACKGROUND: Mood disorders have been described as the commonest psychiatric disorders in patients with temporal lobe epilepsy. Secondary depression in temporal lobe epilepsy could be interpreted either as an adjustment reaction to a chronic disease or as a limbic dysfunction. To clarify this issue, a controlled study of psychiatric disorders was conducted in different forms of epileptic and non-epileptic chronic conditions. METHODS: Twenty outpatients with temporal lobe epilepsy, 18 outpatients with juvenile myoclonic epilepsy--a primary generalised seizure disorder--20 matched type I diabetic patients, and 20 matched normal controls were assessed by a structured interview (SADS) and by self rating scales (Beck depression inventory (BDI) and the state and trait anxiety scales STAIX1 and STAIX2). RESULTS: Sixteen (80%) patients with temporal lobe epilepsy fulfilled the criteria for a psychiatric diagnosis at the SADS interview with a significantly higher frequency than patients with juvenile myoclonic epilepsy (22%) and diabetic patients (10%) (P < 0.0001). The most frequent disorder in temporal lobe epilepsy was a mood disorder: 11 (55%) patients with temporal lobe epilepsy had depression compared with three patients with juvenile myoclonic epilepsy and two diabetic patients (P < 0.001). Eight patients with temporal lobe epilepsy with an affective disorder also had a comorbid personality or anxiety disorder. Patients with temporal lobe epilepsy scored significantly higher on BDI, STAIX1, and STAIX2 than the three control groups (P < 0.001, P < 0.01, P < 0.001). CONCLUSIONS: Patients with temporal lobe epilepsy have a higher incidence of affective and personality disorders, often in comorbidity, than patients with juvenile myoclonic epilepsy and diabetic patients suggesting that these psychiatric disorders are not an adjustment reaction to a chronic disease but rather reflect a limbic dysfunction.

Adult↗
PubMed1995

A microscopic and immunocytochemical study of structural changes in dysfunctional human temporomandibular joint discs.

The central part of 12 articular discs from patients with serious alterations in function of the temporomandibular joint were investigated. The control discs were removed at autopsy from individuals who did not have any such functional defects. The anomalous discs had an increased cellular component; fibrocytes, fibroblasts, numerous myofibroblasts and, less frequently, smooth muscle cells and mast cells were present. The myofibroblasts, which had numerous bundles of thin filaments in the cytoplasm, were positive to the immunocytochemical reaction with antibody to alpha-smooth muscle actin. In one disc only a large part had changed into a mostly fatty tissue. In the majority of the altered discs, the part examined, which usually is neither vascularized nor innervated, was characterized by the presence of numerous blood vessels. Besides the capillary network several larger vessels were present. In one disc, several myelinated and unmyelinated fibres, isolated or in nerve bundles, were also seen. These observations show that the disc fibrous tissue may undergo deep structural modifications that appear to indicate not only a capacity for repair but also an ability to adapt to new functional conditions.

Actin Cytoskeleton↗
PubMed1995

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition.

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

Calcinosis↗
PubMed1994

Detection and determination of selenoproteins by nuclear techniques.

Microbeam X-ray spectrometry, energy-dispersive X-ray fluorescence analysis, and neutron activation analysis were evaluated for the detection of selenium contained in the selenoprotein glutathione peroxidase. The glutathione peroxidase had been previously separated using polyacrylamide gel electrophoresis. The use of Bragg-reflected polarized X-ray beams was employed in the X-ray fluorescence measurements to minimize the problem of scatter owing to the gel matrix. Current detection limits of selenium in a gel matrix are 2.1 ng in the bench-top microbeam X-ray system and 30-60 ng using XRF with polarized beams. Neutron activation analysis was used for quality-control measurements, with a detection limit here of < 0.08 ng. The work has in principle established the feasibility of such an approach.

Animals↗
PubMed1994

Collagen fiber arrangement in temporo-mandibular joint (TMJ) disks from human subjects with functional diseases. Scanning electron microscopy investigations.

Twelve articular disks from patients with temporo-mandibular joint (TMJ) arthropathy were studied and compared with two normal disks. Scanning electron microscopy (SEM) examination of the surfaces and of longitudinal and cross-sections of the disks allowed the observation of the arrangement of the collagen fiber component in different parts of the disk. The superficial part of the articular disks appears to be formed by rather compact fibers. The internal portion is usually formed by bundles of collagen fibers in sheets, alternating with isolated fibers arranged in a parallel or irregular way. In some samples, blood vessels were observed. Our investigations suggested that the appearance of vascularization is the first remarkable histological change that can be observed in functionally abnormal articular disks.

Collagen↗
PubMed1993

[Dynamic magnetic resonance of the temporomandibular joint. Observations and findings].

Condylar movements can be executed only if the TMJ morphology can satisfy functional needs of the masticatory apparatus. Articular components have to be in good relation with dento-skeletal functional anatomy: if this does not occur, mandibular dynamics may establish some functional stresses on the condylar head and the articular eminence. These overloaded structures and particularly their functional surfaces react to this situation to be remodelling and deformation of the articular cavity. In our work we have used a new method to analyse condylar dynamics using MRI. The reconstruction of mandibular movements, using this instrumentation, permits to make some useful observations on the functional capability of TMJ to adjust itself to different maxillofacial morphologies and, consequently, how this joint can fall in a dysfunctional and pathological condition.

Humans↗
PubMed1991

Psychiatric diagnoses in ulcerative colitis. A controlled study.

Fifty patients with UC and 50 matched controls with urolithiasis were interviewed with the SADS (lifetime version) and completed the SCL-90. According to information given during the SADS, there was a history of psychiatric disturbance in 11 UC patients (22%) and 8 controls (16%). At the time of the interview a psychiatric disturbance was present in 31 UC patients (62%) and four controls (8%), the most frequent diagnoses in the former being minor depression and generalised anxiety disorder. Patients with UC scored significantly higher than the controls on all the different SCL-90 subscales.

Adolescent↗