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Biomedical subjects

A Hermansson

Publications and source records attributed to A Hermansson.

15 recordsLinked to original sources
PubMed1992

Mucosal immunoreactivity in experimental pneumococcal otitis media.

A rat model was used to investigate immunological events in the middle ear mucosa during pneumococcal acute otitis media (AOM). Twelve healthy male Sprague-Dawley rats were challenged in the right middle ear with Streptococcus pneumoniae type 3, the presence of AOM being confirmed by otomicroscopy. Randomly selected rats, four at a time, were sacrificed on days 7, 14 and 56 after bacterial challenge. Immunohistochemical staining for IgG, secretory IgA (SIgA), and IgM was performed on tissue specimens from four separate locations in the middle ear and tubal mucosa. Immunoglobulins, especially IgG, were found around blood vessels in the middle ear mucosa. Immunoreactive lymphoid cells of all three Ig classes investigated, undetectable before bacterial challenge, appeared within 7-14 days after middle ear challenge, and the location of these cells in the middle ear mucosa suggests the presence of IgG, SIgA, and IgM, respectively. On the other hand, reactivity with anti-SIgA (but not with anti-IgG or anti-IgM) in Eustachian epithelial cells, and also in the subepithelial glands of tubal mucosa was present both before and after challenge. The results suggest that the middle ear mucosa is an immunoreactive site only after it has been activated with pathogens. In contrast, the tubal mucosa exhibits immunological activity also prior to the antigenic stimulation of present interest.

Animals↗
PubMed1991

Mucosal changes induced by experimental pneumococcal otitis media are prevented by penicillin V.

Penicillin V (pcV) was administered to 50 rats, either before bacterial challenge (prevention group), or after bacterial challenge but before fulminant purulent acute otitis media (AOM) was established (early treatment group). Five animals from each group were killed on days 4, 8, and 12, and 2 and 6 months after challenge. Middle ear mucosa was sampled at six different sites and studied in the light microscope. Untreated pneumococcal AOM in the rat has been shown to cause persistent structural changes of the middle ear mucosa. Both in the early treatment group and in the prevention group, the structural changes were diminished, as compared with those of untreated infected controls. The persistent structural changes seen after 6 months in untreated controls were not seen in animals that had received pcV in conjunction with the AOM episode. Though the beneficial effect on the mucosal changes during the first 2 weeks was more pronounced when pcV was given prophylactically, its use as early treatment would seem to be almost as effective in preventing the persistence of mucosal changes.

Acute Disease↗
PubMed1991

Experimental recurrent pneumococcal otitis media. Protection and serum antibodies.

To elucidate immune mechanisms in otitis media, middle ear infection was induced in 12 rats by intratympanic inoculation of Streptococcus pneumoniae type 3, either the ipsilateral or the contralateral middle ear being re-challenged 4 weeks later. Otomicroscopy inspection confirmed the presence of acute otitis media (AOM) in all rats after the first challenge. After re-challenge, protection against AOM was noted both in the ipsilateral and contralateral ears. Serum antibody concentrations increased after the initial challenge, reaching a maximum at 4-7 days, but had decreased to pre-immune levels at re-challenge, after which no new increase was noted. Serum IgG-antibodies to pneumococcal type 3-polysaccharide were triggered following the initial induction of unilateral pneumococcal AOM, but mucosal immune mechanisms are argued to be a more probable explanation of the ipsilateral protection seen after re-challenge.

Animals↗
PubMed1989

A rat model for bacterial otitis media.

Rat middle ear was exposed to challenge with viable pneumococci, type 3 and 6A, and the course of changes in the middle ear was observed by otomicroscopy and analysis of bacterial samples from blood, nasopharynx and middle ear effusions. Microscopical examination of changes in the middle ear mucosa during and after the acute infection was also made. Depending on the type and concentration of pneumococci, three different results were observed: otitis media with purulent effusion, otitis media with serous effusion, or no reaction at all. The mortality rate was low and most animals recovered within 10 days without postinfectional changes visible by otomicroscopy. The microscopical examination of the middle ear mucosa revealed distinct changes. Inoculation of rat middle ear with pneumococci causes a self-limiting infection that closely resembles acute otitis media in the human. Thus the rat would seem to be a suitable animal model for the study of bacterial otitis media.

Acute Disease↗
PubMed1986

Sensory and autonomic innervation of non-hairy and hairy human skin. An immunohistochemical study.

Non-hairy and hairy human skin were investigated with the use of the indirect immunohistochemical technique employing antisera to different neuronal and non-neuronal structural proteins and neurotransmitter candidates. Fibers immunoreactive to antisera against neurofilaments, neuron-specific enolase, myelin basic protein, protein S-100, substance P, neurokinin A, neuropeptide Y, tyrosine hydroxylase and vasoactive intestinal polypeptide hydroxylase and vasoactive intestinal polypeptide (VIP) were detected in the skin with specific distributional patterns. Neurofilament-, neuron-specific enolase-, myelin basic protein-, protein S-100, neuropeptide Y-, tyrosine hydroxylase- and vasoactive intestinal polypeptide (VIP)-like immunoreactivities were found in or in association with sensory nerves; moreover, neuron-specific enolase-, myelin basic protein-, protein S-100, neuropeptide Y-, tyrosine hydroxylase- and vasoactive intestinal polypeptide (VIP)-like immunoreactivities occurred in or in association with autonomic nerves. It was concluded that antiserum against neurofilaments labels sensory nerve fibers exclusively, whereas neuron-specific enolase-, myelin basic protein- and protein S-100-like immunoreactivities are found in or in association with both sensory and autonomic nerves. Substance P- and neurokinin A-like immunoreactivities were observed only in sensory nerve fibers, and neuropeptide Y- and tyrosine hydroxylase-like immunoreactivities occurred only in autonomic nerve fibers, whereas vasoactive intestinal polypeptide (VIP)-like immunoreactivities was seen predominantly in autonomic nerves, but also in some sensory nerve fibers.

Autonomic Fibers, Postganglionic↗
PubMedDate not supplied

Surfactant and isoprenaline effect on eustachian tube opening in rats with acute otitis media.

Purulent otitis media was induced in 12 middle ears of Sprague-Dawley rats by inoculation of pneumococci type 3. The pressure required to open the eustachian tube was recorded 4 days later and was found to be 3.05 +/- 0.10 kPa (mean +/- SEM), which was 1.08 +/- 0.15 kPa lower than the mean value obtained in a control group of healthy rats (P less than or equal to .001). We also measured the effects of pulmonary surfactant instilled into the middle ear as well as isoprenaline injected intravenously. The presence of surfactant further reduced the pressure opening level by 0.72 +/- 0.05 kPa; this reduction did not differ from that found in the control group (P greater than .8). Isoprenaline reduced the pressure opening level in the control group by 0.20 +/- 0.03 kPa (P less than or equal to .001), and no reduction was found in the rats with otitis media. Although the part played by surface tension-lowering factors in eustachian tube function is still uncertain, such factors apparently also exert an effect in the inflamed tube. However, isoprenaline, which is considered to act by the secretion of surface tension-lowering substances, did not facilitate opening of the eustachian tube in rats with acute otitis media.

Animals↗
PubMedDate not supplied

A rat model for pneumococcal otitis media.

The middle ears of 29 male Sprague-Dawley rats were injected with viable pneumococci, type 3 or 6A, and changes were monitored by otomicroscopy and analysis of bacterial samples from middle ear effusions, blood, and the nasopharynx. Depending on the type of pneumococci and its concentration, three responses were noted: otitis media with purulent effusion, otitis media with serous effusion, or no reaction. The mortality rate was low and the animals recovered without permanent deterioration or otomicroscopically discernable change. The results of this study show the rat to be a suitable animal model for the study of bacterial otitis media.

Animals↗
PubMedDate not supplied

Prevention of experimental acute otitis media with penicillin V.

The preventive effect of penicillin V (pcV) in pneumococcal otitis media in the rat has been studied. The pcV was administered either before bacterial challenge (prevention group) or after challenge but before the establishing of acute purulent otitis media (AOM) (early treatment group). In both cases a fulminant infection was avoided. Thus, in the prevention group no animal developed AOM and in the early treatment group the fulminant AOM was avoided in all cases. These results give further support to the idea of using long-term treatment with an antibiotic with a narrow spectrum to avoid recurrent AOM (rAOM). Furthermore the observation that early treatment might stop the development of fulminant AOM indicates another more restrictive possibility to use antibiotic as a prophylactic measure in otitis-prone children.

Acute Disease↗
PubMedDate not supplied

Effect of gammaglobulin on pneumococcal otitis media in the rat.

Previously it has been found possible to induce pneumococcal AOM that closely resembles human infections, in the rat. In this study, the rat model has been used to study the possibilities to affect the infection by administration of gammaglobulin. The gammaglobulin was administered either systemically by intravenous injection of 0.2 g/kg bodyweight in 15 rats, or topically when 8 mg was instilled into the middle ear cavity of 18 rats. Although intravenous administration in this model failed to provide protection from AOM, topical administration simultaneously with the bacterial challenge was successful.

Administration, Topical↗
PubMedDate not supplied

Persistent structural changes in the middle ear mucosa of the rat, after an experimentally induced episode of pneumococcal otitis media.

To examine the effect of a transient episode of purulent AOM on the middle ear mucosa, an animal model was used. Histological examination was performed after inoculation of pneumococci into the rat middle ear. At 4, 8 and 12 days, and at 2 months after the inoculation, rats were sacrificed on each occasion and samples taken from specific areas of the middle ear mucosa. Structural alterations were noted at all mucosal sites. The normally flat epithelium had become more cuboidal or cylindrical, and numerous ciliated cells occurred in areas originally devoid of these cells. Epithelial cells penetrated the subepithelium forming gland-like structures. In the early phase, day 4 and day 8, inflammatory cells invaded the subepithelial layer except in the tympanic membrane. At 2 months, with the tympanic membrane otimicroscopically and histologically normalized, the structural changes of the mucosa still persisted indicating that a transient episode of pneumococcal otitis media can cause persisting mucosal changes.

Acute Disease↗