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Biomedical subjects

M Bergamini

Publications and source records attributed to M Bergamini.

At least 19 recordsLinked to original sources
PubMed2002

Ultrastructural abnormalities of muscle spindles in the rat masseter muscle with malocclusion-induced damage.

Human temporomandibular disorders due to disturbed occlusal mechanics are characterized by sensory, motor and autonomic symptoms, possibly related to muscle overwork and fatigue. Our previous study in rats with experimentally-induced malocclusion due to unilateral molar cusp amputation showed that the ipsilateral masseter muscles undergo morphological and biochemical changes consistent with muscle hypercontraction and ischemia. In the present study, the masseter muscle spindles of the same malocclusion-bearing rats were examined by electron microscopy. Sham-operated rats were used as controls. In the treated rats, clear-cut alterations of the muscle spindles were observed 26 days after surgery, when the extrafusal muscle showed the more severe damage. The fusal alterations affected predominantly capsular cells, intrafusal muscle fibers and sensory nerve endings. These results suggest that in the malocclusion-bearing rats, an abnormal reflex regulation of the motor activity of the masticatory muscles may take place. They also allow us to hypothesize that muscle spindle alterations might be involved in the pathogenesis of human temporomandibular disorders.

Animals↗
PubMed2001

Factors influencing vaccine uptake in Italy.

In Italy, vaccination of children is regulated by a dual system, that is a certain number of compulsory immunisations, and a number of other facultative vaccinations. This has resulted in a different coverage against infections under the two regimens. While the percentage of immunised children against polio, diphtheria, tetanus and hepatitis B is around 95%, until recently the average coverage with facultative vaccinations was no >50%. Coverage against pertussis has dramatically increased in recent times thanks to the advent of acellular and combined vaccines. Regional programmes that aim to increase coverage against measles, mumps and rubella are presently underway. In order to verify the attitude of mothers towards vaccination, a questionnaire-based study was proposed to women taking their children to vaccination services for mandatory immunisation. The preliminary results on 300 questionnaires show a generally favourable attitude towards vaccines of 80% of mothers. Only 7% of them would not immunise at all their children if vaccinations were not mandatory. Measles and mumps vaccines are considered important by 92% of mothers. However, a high number of both parents and paediatricians still give disproportionate importance to mild intercurrent diseases as a reason to differ immunisation. In the middle-long term, it is likely that Italy will shift to a system of recommended immunisations without compulsion. Before this happens, wide and in-depth campaigns on the benefits of vaccination need to be planned and implemented by central and local health authorities, in order to avoid the risk of a dramatic drop of coverage.

Attitude↗
PubMed2001

Dantrolene counteracts the masseter muscle damage induced by artificial occlusal wear: studies in a rat model.

In previous studies, we showed that the introduction of occlusal alterations to rats results in masseter muscle abnormalities. Here, we investigate whether administration of the muscle relaxant dantrolene to rats with occlusal alteration could counteract the occurrence of such abnormalities. Rats underwent unilateral amputation of molar cusps to cause malocclusion. Some rats received dantrolene (10 mg/kg/day subcutaneously). The masseter muscles ipsilateral to the amputated molars were excised 26 days later. Sham-operated rats were used as controls. The tissue samples were studied by light and electron microscopy and morphometry. Moreover, tissue Ca2+ content, an index of muscle injury, was determined. In the absence of dantrolene, occlusal alteration leads to microvessel constriction, morphologic damage of masseter muscle fibers and blood capillaries, and elevation of tissue Ca2+ content. These changes were nearly abrogated by dantrolene, thus supporting it as a possible new therapeutic tool for the treatment of malocclusion-induced muscle diseases.

Analysis of Variance↗
PubMed2000

Evidence of increased carriage of Corynebacterium spp. in healthy individuals with low antibody titres against diphtheria toxoid.

This study evaluated whether a correlation exists between carriage of corynebacteria and the lack of immunity to diphtheria toxoid. Samples of both nasal and pharyngeal secretions were taken from 500 apparently healthy subjects of both sexes and of all ages and inoculated onto Tinsdale's medium. A serum sample was also taken for ELISA test to determine the titre of diphtheria toxin antibodies. None of the subjects carried Corynebacterium diphtheriae. Ninety-three strains of Corynebacterium spp. were isolated from 93 subjects and 86 of these were classified to species or group level by biochemical tests. C. xerosis was the most common (25.8%) followed by C. pseudodiphthericum (16.1%), C. jeikeium and C. striatum (both 10.8%), and C. urealyticum (9.7%). Three other species accounted for approximately 20% of strains and seven were unclassified as biochemically atypical corynebacteria. Non-protective antibodies to diphtheria toxin were found in 80 of the 93 subjects and a strong statistical association was demonstrated between carriage of corynebacteria and non-protective levels of anti-toxin antibodies. The remaining 13 subjects had protective levels of antitoxin antibodies. In contrast, only 45 of the 407 non-colonized subjects had non-protective antitoxin titres. The prevalence of carriage increased with age among males as did the percentage of non-protected subjects. The prevalence of female carriers of corynebacteria was significantly lower. Serum samples from 12 subjects with different antibody titres to diphtheria toxoid reacted to varying degrees with whole-cell lysates of a number of species of corynebacteria. The results suggest that a causal relationship may exist between nasopharyngeal carriage of corynebacteria and a low anti-diphtheria toxin immune response.

Adolescent↗
PubMed1999

Prevalence of diphtheria toxin antibodies in human sera from a cross-section of the Italian population.

A polycentric study was carried out between 1993 and 1995 in order to evaluate diphtheria immunity on a representative sample of population from different areas of Italy. To determine diphtheria antitoxin, sera from 5187 apparently healthy subjects, divided according to sex and age groups, were titrated using an ELISA indirect method. A basic protective titre of diphtheria antitoxin (> 0.01 IU ml-1) was found in 4080 (78.6%) subjects. No statistically significant differences between males and females were observed. Our findings show that the proportion of susceptibles increases with age and a high proportion of adults no longer has diphtheria antitoxin at protective levels since toxigenic C. diphtheriae circulation is presently lacking in Italy.

Adolescent↗
PubMed1999

Morphologic and biochemical changes of the masseter muscles induced by occlusal wear: studies in a rat model.

Occlusal alterations may result in changes in the functional performance of masticatory muscles. In this study, we set up an experimental model in rats to examine whether masticatory muscle abnormalities occur after a malocclusion is induced. Rats underwent unilateral amputation of the molar cusps to simulate an occlusal wear situation. The masseter muscles ipsilateral and contralateral to the amputated molars were excised at different experimental times. Sham-operated rats were used as controls. The tissue samples were studied by light and electron microscopy and morphometry. Tissue calcium content, a biochemical index of muscle injury, was also determined. The results show that occlusal dysfunction leads to microvessel constriction and clear-cut morphologic damage of muscular fibers and blood capillary endothelium, as well as to elevation of tissue calcium content, in the ipsilateral masseter muscle. These changes are likely related to muscle fatigue and ischemia. The early signs of injury do not involve the entire muscle but are mostly restricted to tissue areas rich in type I (slow) muscle fibers, which are characterized by a predominantly aerobic metabolism. The muscle damage becomes more extended and severe with time. On the other hand, the contralateral muscles show only slight alterations which are reversible with time, possibly due to an adaptive response.

Analysis of Variance↗
PubMed1997

Immunity to diphtheria in Siena.

The aim of this study, carried out in 1993, was to evaluate diphtheria immunity in Siena. Diphtheria antitoxin levels were measured by means of the immunoenzymatic test (ELISA) in serum samples of 602 apparently healthy subjects (239 males and 363 females) of all ages residing in Siena. According to widely used criteria, 6% of the total population were susceptible to diphtheria (antibody levels < 0.01 IU/ml), 71% had basic protection (0.01-0.09 IU/ml) and 23% were fully protected (> or = 0.1 IU/ml). The results suggested that a high proportion of young population had a protective level of immunity against diphtheria, that susceptibility increased with age and a smaller proportion of males (2.9%) than females (8.3%) were unprotected; this difference was statistically significant. Our results suggest that it may be useful to revaccinate adults with low levels of diphtheria toxoid so that the percentage that remains unprotected does not put the community at risk of an outbreak of diphtheria.

Adolescent↗
PubMed1997

Submicroscopic mathematical evaluation of spermatozoa in assisted reproduction. 4. The bovine fertilization (Notulae seminologicae 10).

In this paper we apply a modification of the formula of Baccetti et al. (1995) in the evaluation of submicroscopical characteristics of bull spermatozoa used in assisted reproduction. In the present experiment sperm quality is proposed as a useful parameter in predicting the success of fertilization. Our results demonstrate that the percentage of spermatozoa devoid of submicroscopic defects, according to the particular Bayesan formula proposed by us, is clearly correlated with the result of artificial insemination. In fact, the parameter concerning sperm quality obtained in variously successful donors shows a large correlation with fertility power. The synthetic parameters observed are therefore a good tool in the prediction of sperm power in artificial fertilization. The evaluation is mainly concerned with the quality of the acrosomal characters, the status of the chromatin, the shape of mitochondria, the position of the postacrosomal sheath, the perinuclear space and the axonemal pattern. All these characters are expressed with different means in ejaculates. All these data confirm that submicroscopic-mathematical evaluation offers a convincing and reliable diagnosis based upon sperm structure and functions such as acrosomal reaction and cell motility. It has been also demonstrated that sperm quality is a major factor in the success of artificial insemination and it is clearly revealed in the integrity of most of sperm organelles.

Animals↗
PubMed1996

Radicular cysts are involved in the recruitment of osteoclast precursors.

In consideration of the close relationship between radicular cysts and alveolar bone, it is important to evaluate the potential involvement of the neighbouring bone tissue in such lesions. In the present study, using cytochemical, immunocytochemical and morphological analyses, presumptive osteoclast precursors were revealed in the connective tissue of radicular cyst capsules. The osteoclastic nature of these cells was postulated by their positive staining for the enzyme tartrate-resistant acid phosphatase (TRAP) and by the expression of vitronectin receptor (VnR) on their cell surface. However, these cells did not express the vacuolar-type proton pump, suggesting that they may represent early osteoclast precursors infiltrating the cyst capsule. Cysts also contained activated small blood vessels whose endothelial cells expressed the VnR. This integrin receptor is important in the adhesion of preosteoclasts to the endothelial lining, a necessary step for their emigration out of the vasculature. Therefore, the intracystic vessels could represent a substrate for preosteoclast recruitment. These precursor cells may then reach the perialveolar bone surface and contribute to bone demolition together with those recruited by the resorbing surfaces. The bone-destroying potential of radicular cysts was confirmed by the presence of numerous osteoclasts with large resorption areas on the perialveolar bone surfaces exposed to the cyst capsules. The resorbed surfaces were usually located around the vascular canals of the Haversian systems.

Acid Phosphatase↗
PubMed1996

Odontogenic jaw cysts: light and electron microscopical investigations.

Light and electron microscopy were used to analyze the epithelial lining of odontogenic cysts excised from edentulous regions of the jaws. Clinically, three cases were identified as keratocysts, and 21 cases as cysts other than keratocysts ("non-keratocysts"). The epithelium of the former was found to achieve keratinization over most of the surface and to never contain mucus secreting cells. The epithelium of the latter appeared to be in part stratified squamous, with cells loosely connected to each other, and in part stratified columnar, with superficial cells connected to each other by tight junctions and secreting mucus. The results suggest that cysts arising from edentulous regions of the jaws may be either keratocysts or cysts with heterogeneous, non-keratinizing epithelium; the content of keratocysts can be formed mainly by shedding of cornified epithelial layers, and that of non-keratocysts by mucus secretion from columnar epithelium associated to fluid filtration through non-keratinizing squamous epithelium.

Epithelium↗
PubMed1995

Osteolytic processes in human radicular cysts: morphological and biochemical results.

In an attempt to verify the nature of bone resorption processes on the bone surrounding radicular cysts, fragments of cysts with the adjacent bone tissue were studied by morphological, cytochemical and ultrastructural methods. Cyst fluid was analysed for its content of cytokines with osteolytic activity. The cyst wall exhibited several connective tissue extensions which penetrated the adjacent bone. Numerous multinucleated tartrate-resistant acid phosphatase (TRAP)-positive cells were seen at the tip of the intraosseous extensions of the cyst capsule and in direct contact with the bone tissue. Typical resorption lacunae were identified on the bone surface by scanning electron microscopy. Moreover, mononuclear TRAP-positive cells were seen within the cyst capsule. High levels of prostaglandin E2 (PGE2) and interleukin-6 (IL-6) were detected in the cyst fluids. In conclusion, active bone resorption may contribute significantly to the growth of these lesions within the jaws.

Acid Phosphatase↗
PubMed1995

[Highlights in the subject of low frequency-high intensity TENS (review)].

Transcutaneous electrical neural stimulation (l.f.-h.i. TENS), employed in dentistry, allows masticatory muscles relaxation, temporary clearance of muscular and periodontal proprioceptive input and even oro-facial pain relief. The mechanisms involved in this type of stimulation are not entirely clarified. According to the most recent neurophysiological researches, the authors describe several l.f.-h.i. TENS. action modalities. Some of them are well known such as the gate control theory, the endogenous antinociceptive system activation, the metabolic recovery of the muscular tissue and the unloading reflex. Other mechanisms, instead, are less known such as hypnosis and stress analgesia, exteroceptive suppression and counterirritation (DNIC). Some hypothetical mechanisms are also considered such as endogenous inhibition and sympathetic activity reduction.

Acupuncture Analgesia↗