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Biomedical subjects

R T Thomeer

Publications and source records attributed to R T Thomeer.

15 recordsLinked to original sources
PubMed1992

Transient expression of stage-specific embryonic antigen-1 (CD15) in the developing dorsal rat spinal cord.

The localization of CD15 (synonyms: stage-specific embryonic antigen-1 (SSEA-1), 3(alpha)-fucosyl-N-acetyl-lactosamine or FAL), which is implicated in neuronal differentiation, in the developing dorsal rat spinal cord was studied by immunocytochemistry. A embryonal day 9 (E9), SSEA-1 was detected in the neural ectoderm and, at E11, in cells near the ventricle of the matrix layer. This localization indicated that SSEA-1 is present in proliferating premigratory cells of the rat spinal cord. Between E12 and E16, cells of the alar plate expressed SSEA-1. Expression of the antigen was restricted to neuroblasts that will form the dorsal horn. SSEA-1, therefore, can be used at this stage as a marker for a subdivision of the matrix layer. At E14, the dorsal root entrance zone showed SSEA-1. This indicated that SSEA-1 is associated with ingrowing primary afferents. From E16 on, SSEA-1 was present in the dorsal raphe, which suggested a function for SSEA-1 in the guidance of developing fibres. After E17, the antigen was also found within the dorsal mantle layer. SSEA-1 was first present in Rexed's laminae II, IV and V. Later on in development the antigen was detected only in Rexed's laminae II (substantia gelatinosa). These distribution patterns indicated that SSEA-1 is present on migratory and/or postmigratory cells. In addition, SSEA-1 is associated with small-diameter dorsal root fibres, the C fibres and A(sigma) fibres, that terminate within the substantia gelatinosa. After birth, SSEA-1 was present throughout the dorsal horn, probably as a result of the myelination of the fibres.

Animals↗
PubMed1992

Open fetal spinal cord surgery in rats with low mortality achieved by prevention of oligohydramnios.

Myelotomies were performed with an open microsurgical technique in rat fetuses aged between E16 and E18. In 87 consecutively treated fetuses the net surgical mortality was as low as 7%. The cause of death due to fetal surgery is shown to be amniotic fluid loss. The high survival rate is attributed to the prevention of oligohydramnios. The technique is described in detail and the results are discussed.

Animals↗
PubMed1991

Recovery of brachial plexus injuries.

Despite technical advances, the ability to restore function following severe brachial plexus traction lesions is limited. Major problems hampering good results are the inability to recognize corresponding fascicles in case of a large nerve gap and the lack of a proximal nerve stump in root avulsions. This article discusses the diagnosis and treatment of such injuries in combination with research in this field.

Brachial Plexus↗
PubMed1990

Ventral root avulsions of the cat spinal cord at the brachial plexus level (cervical 7).

The ventral cervical 7th root was avulsed from the surface of the cat spinal cord, and studied using light microscopical stainings (Nissl, acetylcholinesterase and antibodies against neurofilament and glial fibrillary acidic protein) after different survival times. After two days the density of the neurofilament increased in the neurons in the ventral horn of the avulsed ventral root. Changes in the rough endoplasmatic reticulum (Nissl and acetylcholinesterase) started four days postoperatively, and were confirmed electron microscopically. The glial fibrillary acidic protein-positive structures surrounding the injured neurons in the avulsed ventral horn became more pronounced 30 days postoperatively. The number of neurons was definitely decreased 60 days after the avulsion. After the initial phase of the avulsion and before the distinct decrease in the number of neurons, the conditions for reimplantation of the avulsed ventral root and for the supposed regeneration can be expected to be more favourable for the neurons in the ventral horn.

Acetylcholinesterase↗
PubMed1990

Enzyme histochemistry of the spinal cord after experimental transection (Th 9) in the cat.

Subpial complete resection of a 10 mm segment of the spinal cord at Th 9 was performed in 9 adult cats. Topographic enzyme histochemical investigations of the terminal clubs were performed after different survival times after transection in 7 cats and three days after a subsequent one-week-delayed autologous sciatic grafting procedure in the remaining two cats. For acid phosphatase (ACP), the count of active terminal clubs was high (200 per m2) from 12 hours until day 3 after transection. Then the count of active terminal clubs decreased to a low level (20 per m2) and remained the same until day 14. Removal of necrotic tissue and subsequent grafting with autologous sciatic nerve did not change these findings. For succinate dehydrogenase (SDH), the numbers of terminal clubs showed the same pattern at a lower level. The SDH defined terminal clubs were smaller than the ACP ones. The length of the SDH positive area decreased after 7 days while the ACP positive area remained the same until day 14. The SDH active terminal clubs are overgrown by the ACP positive terminal clubs, after the 7th day. Considering that SDH is linked to constructive activity in mitochondria and ACP to destructive activity in lysosomes, this phenomenon might be responsible for the termination of the capacity of the spinal cord tissue to regenerate.

Acid Phosphatase↗
PubMed1989

Optic glioma with intraocular tumor and seeding in a child with neurofibromatosis.

We treated a 3-year-old boy with neurofibromatosis who had an optic glioma, intraocular extension with seeding, and iris tumors. On the basis of results of ultrasonography, computed tomography, magnetic resonance imaging, and fine needle aspiration, other intraocular and orbital tumors were excluded. Because of the malignant intraocular aspect, the optic nerve glioma was extirpated. Histologic examination confirmed the diagnosis of an optic nerve glioma with intraocular extension, seeding, and iris nodules. In this juvenile pilocytic astrocytoma with secondary perineural fibrous hyperplasia, several mitoses were found in the orbital and intraocular parts. In the optic canal, three small islands were found that were compatible with the diagnosis of malignant astrocytoma, grade 3. The iris nevi appeared as iris pits and not like the Lisch nodules typical of neurofibromatosis. Café au lait spots were present on the skin. The family history was positive for neurofibromatosis. The results of this study demonstrate that optic gliomas are true astrocytomas and not hamartomas, and have a continuous scale from benign to malignant differentiation.

Child, Preschool↗
PubMed1989

[Temporary lumbar external drainage in normal pressure hydrocephalus].

In a prospective study twenty-two patients diagnosed as suffering from idiopathic normal pressure hydrocephalus, were investigated using temporary external lumbar drainage. Five patients had to be excluded from the study because of complications of external lumbar or definite ventricular shunting. External drainage correctly predicted the outcome of shunting in all of the remaining seventeen patients. This technique appears to be a safe and valuable tool for predicting the outcome of definitive shunting procedures.

Aged↗
PubMed1988

Spinal cord transections in fetal rats. Open intrauterine surgery with low mortality.

Open myelotomies were performed in rat fetuses in stages E15-E19 with a microsurgical technique. To prevent oligohydramnios, considered to be one of the main causes of death associated with fetal surgery, amniotic fluid loss was reduced as much as possible. With this technique a reduction of the mortality rate to 38% was reached in 75 consecutive fetuses.

Animals↗
PubMed1988

Predictive value of temporary external lumbar drainage in normal pressure hydrocephalus.

In a prospective study on the effect of shunting, 22 patients diagnosed as suffering from normal pressure hydrocephalus (NPH) were investigated by means of temporary external lumbar drainage (ELD). Five patients had to be excluded from the study because of complications of ELD or definitive shunting. ELD correctly predicted the outcome of shunting in all of the remaining 17 patients. The value of external lumbar drainage in NPH is discussed on the basis of personal experience and data from the literature. It seems to be a safe and valuable tool for predicting the outcome of definitive shunting procedures.

Aged↗
PubMed1987

Choroid plexus papilloma in the posterior fossa.

Choroid plexus papillomas in the posterior fossa can present with different clinical signs and symptoms. The tumors in the patients we discuss in this article originated from different sites of the choroid plexus. One patient, who had a fourth ventricle papilloma, experienced unsteady gait and episodes of dizziness over many years. The tumor was cystic an calcified, and adherent to the brain-stem. The second patient had only signs of increased intracranial pressure. A soft tumor was located in the cerebellomedullary cistern. The third patient, with a papilloma in the cerebellopontine angle, complained of hearing loss. This tumor was firmly adherent to the dura mater and looked exactly like a meningioma. The appearance on computed tomography scan, the macroscopic aspect, and the vascular supply of a papilloma in the posterior fossa can vary considerably.

Adult↗
PubMed1978

Basilar impression in an achondroplastic dwarf: causative role in tetraparesis.

The neurological and radiological findings in a case of chondrodystrophic dwarfism are described. The progressive tetraparesis proved to be based on a high-level medullary compression resulting from basilar impression and upper cervical stenosis. Surgical decompression led to the disappearance of the tetraparetic phenomena. Various aspects of chondrodystrophic dwarfism and basilar impression are discussed in relation to the neurological symptomatology, and the question of whether, in general, more attention should be given to the cranio-cervical region, is raised.

Achondroplasia↗
PubMed1978

Recent developments in peripheral nerve surgery. Management of open traumatic peripheral nerve lesions.

The modern technique of operative repair of traumatic nerve interruption is discussed. The results of microsurgical repair have proved to be superior to those of conventional methods. Besides the anatomy and the operative technique, the indications and timing for surgical intervention are discussed. Reference to the literature and the authors' own experience show that delayed primary repair is the method of choice.

Humans↗