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Biomedical subjects

A J Otto

Publications and source records attributed to A J Otto.

At least 19 recordsLinked to original sources
PubMed1996

Retrobulbar pressures measured during surgical decompression of the orbit.

AIMS/BACKGROUND: In Graves' ophthalmopathy the increase in volume of intraocular muscles and fat will cause elevated intraorbital pressure. In order to investigate the pressure levels involved, intraorbital pressure, or retrobulbar pressure (RBP) was measured continuously in orbits of patients with Graves' ophthalmopathy during surgical decompression. METHODS: Retrobulbar pressure was measured before and during surgical decompression using an intraorbitally applied pressure transducer. RESULTS: In eight patients with dysthyroid optic neuropathy (DON) RBPs between 17 and 40 mm Hg were recorded. At the end of the surgical procedure the mean RBP was reduced from 28.7 mm Hg to 18.7 mm Hg, the decrease ranging from 8 to 12 mm Hg, which showed a high correlation with the starting pressures (p < 0.001). In two cases without DON, pressures were 11 and 9 mm Hg. Forces exerted by spatula manipulation usually resulted in a RBP level of more than 70 mm Hg. CONCLUSIONS: This study shows that RBPs are markedly elevated in Graves' ophthalmopathy and that surgical decompression can result in a significant reduction in the intraorbital pressure. Optic nerve dysfunction in Graves' ophthalmopathy may not be caused exclusively by the direct pressure of swollen extraocular muscles upon the optic nerve, but also by a raised RBP. It is hypothesised that the damage inflicted upon the optic nerve can be caused in consequence by RBP induced incarceration of the nerve, compressed by surrounding periosteal lined orbital fat bulging posteriorly into the entrance of the optic canal.

Female↗
PubMed1993

Alterations in skeletal muscle related to impaired physical mobility: an empirical model.

The objective of this investigation was to study impaired physical mobility and the resulting skeletal muscle atrophy. An animal model was used to study morphological adaptations of the soleus and plantaris muscles to decreased loading induced by hindlimb suspension of an adult rat for 7, 14, and 28 consecutive days. Alterations in weight, skeletal muscle growth, and changes in fiber type composition were studied in synergistic plantar flexors of the rat hindlimb. Body weight and the soleus muscle mass to body mass ratio demonstrated significant progressive atrophy over th 28-day experimental period with the most significant changes occurring in the first 7 days of hindlimb suspension. Hindlimb suspension produced atrophy of Type I and Type IIa muscle fibers as demonstrated by significant decreases in fiber cross-sectional area (micron 2). These latter changes account for the loss of contractile force production reported in the rat following hindlimb unloading. When compared to traditional models of hindlimb suspension and immobilization, the ISC model produces a less severe atrophy while maintaining animal mobility and health. We conclude that it is the preferred animal model to address nursing questions of impaired physical mobility.

Adaptation, Physiological↗
PubMed1992

Pigment-containing cells in extraocular tissues of the primate.

In the present study pigment-containing (PC) cells, localized in extraocular tissues of man and the cynomolgus monkey, were investigated to establish their localization, nature and relationships with the autonomic nervous system. In the orbit of man as well as the cynomolgus monkey three localizations of PC cells were detected: (1) Tenon's capsule along the ciliary arteries at the level of the entrance of the arteries into the eyeball, (2) Tenon's capsule along the ciliary nerves at the level of the entrance into the eyeball, and (3) the sclera around the ciliary arteries and nerves. Moreover in the orbit of the cynomolgus monkey PC cells were found along and around the accessory lateral rectus muscle. Histological, histochemical and electron microscopical studies led to the conclusions that PC cells are similar in nature to melanocytes and do not have neuronal properties. In contrast to the melanocytes in the anterior segment of the eye in both man and monkey, melanocytes in the extraocular tissues are not innervated either adrenergically or cholinergically.

Animals↗
PubMed1992

Effect of recovery mode following hind-limb suspension on soleus muscle composition in the rat.

The purpose of this study was to compare the effects of two different recovery modes from hind-limb suspension-induced hypodynamia on whole body and muscle (soleus) growth as well as soleus composition and size changes of different fiber types within this same muscle. Following 28 days of tail-suspension, rats were returned to their cages and sedentarily recovered (HS), or were exercised by running on a treadmill 5 days/wk, at progressively increasing workloads (HR) for one month. Sedentary and running control groups of animals (CS, CR) were also evaluated for comparative purposes. The exercise program, which was identical for CR and HR groups, had no effect on body wt., soleus wt., soleus muscle composition or fiber size in CR rats. Atrophied soleus muscle and reduced soleus wt./body wt. ratio (both 60% of control) had returned to control values by day 7 of recovery in both suspended groups despite the fact that whole body wt. gain was significantly reduced (p less than 0.05) in HR as compared to HS rats. Atrophied soleus Type I fiber mean cross-sectional area in both HR and HS groups demonstrated similar and significant (p less than 0.01) increases during recovery. Increases in Type IIa and IIc fiber area during this same period were significant only in the HR group. While the percentage area of muscle composed of Type I fibers increased in both hypodynamic groups during recovery, the reduction in area percentage of muscle made up of Type IIa fibers was again only significant in the HR group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Willem Vrolik on cyclopia.

One of the founders of the Museum Vrolikianum, Professor Willem Vrolik (1801-1862), was very interested in teratology, especially in a congenital malformation termed cyclopia. In 1834 he published a paper on cyclopia. This work was mainly based on studies of cyclopic specimens present in the collection of his father, Professor Gerardus Vrolik. In this study he proposed a classification system for cyclopes, in which he divided them into five main types. This study also formed the basis for the chapters on cyclopia in his Handbook of pathological anatomy (1842-1844) and his Tabulae ad illustrandam embryogenesin hominis et mammalium (1844-1849). In these studies the specimens of cyclopes of man and mammals, still present in the collection of the Museum Vrolik in the Department of Anatomy and Embryology of the University of Amsterdam, were described and illustrated with beautiful lithographs. The collection consists of five human cyclopes and nineteen other cyclopic mammals. These mammals are pigs, lambs and a cat.

Animals↗
PubMed1991

Primary and secondary implants in the anophthalmic orbit. Preoperative and postoperative computed tomographic appearance.

Sagittal computed tomographic (CT) scans of 10 anophthalmic orbits with a primary implant, an acrylic ball covered with donor sclera, and 10 anophthalmic orbits before and after insertion of a secondary implant were studied. For each patient, the scans of the anophthalmic and contralateral normal orbit were compared. In the anophthalmic orbits, the anatomy was optimally restored in those with a primary implant, and suboptimal results were achieved in the orbits with a secondary implant. The greatest differences were noticed in the orbits without an implant. Differences were noticed for the position and length of the superior muscle complex and the inferior rectus muscle, the position of the upper eyelid, the depth of the superior sulcus, and the backward tilt of the prosthesis. The authors conclude that the rotatory displacement of the orbital contents after enucleation, which explains the sequelae of the anophthalmic orbit, is grossly circumvented by the insertion of an implant. In achieving this effect, primary implants are better than secondary ones.

Adolescent↗
PubMed1991

Prosthesis motility with and without intraorbital implants in the anophthalmic socket.

Ocular prosthesis motility was measured and compared in 15 patients with a primary baseball implant after enucleation of an eye, in 11 patients with a secondary baseball implant, in 12 patients with an Allen implant, and in 11 patients without any intraorbital implant. In all patients a noticeable lag of movement of the prosthetic eye was measured: in the extreme directions of gaze the excursions of the prosthesis were far less in comparison with the contralateral normal eye. For normal eye movement round the primary position of gaze, however, the prosthesis motility in the primary baseball and Allen implant group appeared to be sufficient to give a lifelike appearance. The average motility of the prostheses in these two groups did not differ. The motility in the secondary baseball group and in the group without an implant was evidently worse. In the last group the prosthesis motility was most impaired. We conclude that the insertion of an implant, even when inserted some time after the enucleation (a secondary implant), improves the motility of the prosthesis markedly. We recommend the primary baseball implant as the correction of choice after enucleation.

Adolescent↗
PubMed1990

Computed tomography in the assessment of the postenucleation socket syndrome.

To gain a deeper insight into the cause of the postenucleation socket syndrome, high-resolution computed tomography (CT) was performed in 22 anophthalmic patients before insertion of an intraorbital implant. The anatomy of the normal and the anophthalmic orbits was compared. Computed tomographic scans were made either in the sagittal and the coronal plane or in the sagittal and transverse plane. The authors discovered a sagging and retraction of the superior muscle complex and a downward and forward redistribution of orbital fat. Finally, an upward displacement of the distal end together with a retraction of the inferior rectus muscle was found. These phenomena were measured and appear to cause a rotatory displacement of orbital contents from superior to posterior and from posterior to inferior which is best demonstrated in the sagittal plane. This redistribution of orbital contents can explain the sequelae of the anophthalmic orbit. No signs of orbital fat atrophy could be demonstrated. With this knowledge, the proper treatment of patients with a postenucleation socket syndrome is ascertained.

Adult↗
PubMed1990

Primary versus secondary intraorbital implants.

To compare the results of primary and secondary intraorbital implants after enucleation, we retrospectively studied the surgical outcomes of 114 patients. In 44 patients the implant was inserted immediately after enucleation and in the remaining 70 patients the implant was inserted at a later date. To achieve a satisfactory cosmetic result, additional procedures were needed in 11% of the patients with a primary implant and in 49% of those with a secondary implant. The insertion of an implant at the time of enucleation has distinct advantages over the insertion of the implant at a later date.

Adult↗
PubMed1990

The influence of vitrectomy and lensectomy on experimental uveitis.

A secondary immune response in the rabbit eye can be provoked by intravenous injection of the antigen, previously injected intravitreally. The inflammation process consists of iris hyperemia, pericorneal redness and cellular and proteinous exudates in the anterior chamber and vitreous. The influence of vitrectomy combined with lensectomy or preceded by extracapsular lens extraction on the character of the secondary immune response has been studied in the rabbit eye. Both eyes of adult rabbits were injected intravitreally with human serum albumin. Five to ten weeks later, when the primary inflammation process had vanished, the vitreous and the lens were removed from the right eye in one group of animals. In a second group of rabbits, an extracapsular lens extraction was performed upon both eyes, later followed by vitrectomy of the right eye. Four weeks later all animals received an intravenous booster injection with human serum albumin. The eyes which still contained the vitreous developed a secondary inflammation consisting predominantly of cells and fibrin clots in the anterior chamber however without flare. On the contrary, the eyes which underwent vitrectomy developed a flare in the anterior chamber with only a few cells detectable. Analysis of cells and protein in the anterior chamber and histological evaluation supported the clinically observed differences between both eyes. These results suggest that the persistence of the vitreous is associated with the reactivation of a secondary immune response. Vitrectomy combined with lensectomy or preceded by extracapsular lens extraction leads to increased passive transfer of proteinous material through the vessels.

Animals↗
PubMed1990

Ocular inflammatory activity following different techniques of lens extraction and vitrectomy in rabbits.

The ocular inflammatory activity following different techniques of lens extraction and vitrectomy was studied in rabbits recovered from primary uveitis. Primary uveitis was induced by intravitreal injection of human serum albumin. After five to ten weeks, when the eyes were completely quiet, vitrectomy combined with lensectomy in one session or extracapsular lens extraction followed by vitrectomy was performed in different groups of rabbits. The most intense postoperative inflammatory process was encountered following removal of the lens independently of the route of extraction (via the ciliary body or via the anterior chamber). Vitrectomy via the ciliary body led to a minimal postoperative inflammation which resolved within 7 days. From these results we concluded that vitrectomy in primarily sensitized rabbit eyes can be performed without intense postoperative complications.

Animals↗
PubMed1989

Autonomic pathways in the orbit of the human fetus and the rhesus monkey.

In order to study the three-dimensional topography of the intra-orbital autonomic nerve plexuses and the input for these systems, human fetuses and adult rhesus monkeys were investigated. Specimens of the orbits were processed according to the histochemical acetylcholinesterase methods for staining of peripheral nerves. The nerve fibers enter the orbit along the following pathways: 1. bundles of nerve fibers from the pterygopalatine ganglion (mainly parasympathetic) by penetrating the orbital muscle (Müller); 2. perivascularly along the ophthalmic artery (sympathetic). In the orbit the nerve fibers intermingle. The pathways of the nerve fibers from this interwoven nerve plexus towards the target organs are: 1. perivascularly along branches of the ophthalmic artery; 2. perineurally along and in the branches of the ophthalmic and maxillary nerves; 3. independently of blood vessels and cranial nerve branches in Tenon's capsule. Moreover, bundles of nerve fibers from the ciliary ganglion contribute to the innervation of extraocular structures, e.g. the eyelids. It can be concluded that, as far as the autonomic innervation of the orbit is concerned, the monkey is a good animal model for neuroanatomical studies.

Acetylcholinesterase↗
PubMed1989

Intraocular antibody synthesis during experimental uveitis.

Determination of intraocular antibody synthesis against certain microorganisms is a diagnostic aid in identifying the causative agent in clinical uveitis. Little is known, however, concerning the kinetics and specificity of antibodies produced during intraocular inflammation. To investigate this subject we induced uveitis in rabbits by injecting small amounts of human serum albumin (HSA) into the vitreous. Aqueous humor and serum were taken before and after the induction of uveitis and levels of total IgG, rabbit albumin and anti-HSA-IgG were determined. The anti-HSA-IgG was quantitated using immunoaffinity purified anti-HSA-IgG as a standard. Six weeks after intravitreal HSA injection, high levels of total IgG (4.7 mg/ml) and albumin (15.4 mg/ml) were observed in the aqueous as compared to control eyes (IgG: 0.12 mg/ml; albumin: 0.48 mg/ml). Using albumin to correct for blood aqueous barrier breakdown we calculated that only 0.6% of the locally synthesized IgG was directed against intravitreally injected HSA. Two months after the intravitreal injection of HSA the main signs of the uveitis had subsided. A recurrent uveitis was subsequently induced by an intravenous HSA injection. This resulted in a marked increase of total IgG (14.3 mg/ml) and albumin (24.6 mg/ml) in the aqueous humor of the uveitis eyes. It was remarkable that the mean anti-HSA-IgG level (0.62 mg/ml) in the uveitis eyes was higher than that seen in serum (0.41 mg/ml). After this secondary uveitis, 9% of the locally synthesized antibodies were directed against HSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

What is there still to be said against intra-ocular lenses?

On the basis of 400 cataract extractions with lens implantation, almost all performed by Binkhorst's extracapsular method, the author comes to the conclusion that, after more than 6 years' experience with this method, he sees no essential contraindications to the systematic implantation of an intra-ocular lens after cataract extraction. Detailed attention is paid to the necessary working conditions, the operative method and the operation results.

Aged↗
PubMed1982

Distribution of immunoglobulin-containing cells in the bronchial mucosa of patients with chronic respiratory disease.

Bronchi biopsy specimens of 42 patients with chronic respiratory diseases were studied for immunoglobulin-containing cells, using an indirect immunoperoxidase technique. The number of immunocytes was expressed per unit tissue section surface. The cells were located directly under the epithelium. In most biopsy specimens IgA-, IgG- and IgM-containing cells were demonstrable, with IgA- and IgG-containing cells in the majority. IgE-containing cells were found only in small numbers in biopsy specimens of a few patients. The presence of IgE-containing cells was nearly always accompanied by a high amount of mast cell-bound IgE in the bronchial mucosa. No correlation could be found between the number and class of immunocytes and clinical data.

Adolescent↗