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R Sonntag

Publications and source records attributed to R Sonntag.

16 recordsLinked to original sources
PubMed1991

Development of the amphibian oculomotor complex: evidences for migration of oculomotor motoneurons across the midline.

The development of the oculomotor nucleus in five species of salamanders and one anuran species was investigated with tracing techniques. The data presented support the hypothesis that oculomotor motoneurons innervating the superior rectus muscle migrate across the midline. In the salamander Pleurodeles waltl, only ipsilateral oculomotor motoneurons are labeled in early development. Later, these neurons extend dendrites toward the contralateral side into the ventral tegmental neuropil, after which there is displacement of their nuclei (neuronal somata) across the midline. Cell bodies can be observed directly at the midline. In adult Salamandra salamandra, motoneurons innervating the superior rectus muscle are seen occasionally at the midline and on the ipsilateral side, with dendrites toward the contralateral side. Motoneurons on the ipsilateral side do not display these features. In Pleurodeles, developmental brain processes are slowed down, and the sequence of development of the contralateral subnucleus, which can be clearly observed, supports the migration hypothesis. In Xenopus laevis and most other species of salamanders this process is accelerated.

Ambystoma mexicanum↗
PubMed1991

Sequential double labelling with different fluorescent dyes coupled to dextran amines as a tool to estimate the accuracy of tracer application and of regeneration.

We present a technique to estimate the accuracy of a given application procedure for neuronal tracers. In a second series of animals we used this technique for the estimation of successful regeneration of peripheral nerves. Dextran amine coupled to rhodamine was applied to the cut trochlar nerve in Xenopus tadpoles. To assess the accuracy of tracer application, experiments were done in which a second dye, dextran amine coupled to fluorescein, was applied after 1 day proximal to the first dye. More then 90% of all trochlear motoneurons were doubly labelled after this procedure. Their total numbers were not significantly different from numbers obtained after single labelling with HRP in a comparable age group. To assess success of regeneration after 5 and 8 days, the second application of fluorescein dextran amine was distal to the first application side. Statistically significant differences suggest incomplete regeneration of many neurons. After 42 days the numbers of singly and doubly labelled motoneurons was in the same proportion as before regeneration. This suggests that about 90% of the surviving motoneurons had successfully regenerated back to the periphery.

Amines↗
PubMed1990

Oculomotor (N III) motoneurons can innervate the superior oblique muscle of Xenopus after larval trochlear (N IV) nerve surgery.

The position of motoneurons which reinnervate the superior oblique muscle (SOM), normally exclusively innervated by contralateral trochlear motoneurons, was studied in Xenopus using retrograde tracing techniques. The trochlear nerve was cut at its decussation in 49 larvae of different ages and, after subsequent regeneration, the total number of trochlear motoneurons was found to be reduced to about 50% of the controls. In contrast, the number of ipsilateral trochlear motoneurons was increased. Cutting the trochlear nerve at later stages may result in absence of this nerve. In some animals the SOM was innervated either by superior rectus or, more frequently, by inferior oblique motoneurons alone; the latter is known to act predominantly as an antagonist of the SOM.

Animals↗
PubMed1990

Organization of the six motor nuclei innervating the ocular muscles in lamprey.

The topography of motoneurons supplying each of the six ocular muscles of the lamprey, Lampetra fluviatilis, was studied by selective application of HRP to the cut nerves of identified muscles. In addition, the distributions of motoneuron populations to both eyes were studied simultaneously with fluorescein and rhodamine coupled dextran-amines (FDA and RDA) applied to cut ocular muscle nerves of either side. The motoneuron pool of the caudal oblique muscle is represented bilaterally in the trochlear (N IV) motor nucleus. The dorsal rectus muscle is innervated from a contralateral group of oculomotor (N III) motoneurons and the remaining four muscles exclusively from the ipsilateral side (N III and N VI). The inferior and posterior rectus muscles are both innervated by the abducens nerve. In contrast to all jawed vertebrates, only three eye muscles (the dorsal rectus, rostral rectus, and rostral oblique) are innervated by the oculomotor nerve in lampreys (N III). Lampreys have a motor nucleus similar to the accessory abducens nucleus previously described only in tetrapods. They lack the muscle homologous to the nasal rectus muscle of elasmobranchs and the medial rectus muscle of osteognathostomes. The distribution of the dendrites of different groups of motoneurons was studied and is considered in relation to inputs from tectum and the different cranial nerves.

Animals↗
PubMed1990

Enlargement of regional lymph nodes in renal cell carcinoma is often not due to metastases.

Preoperative axial computerized tomography scans in 163 patients with renal cell carcinoma were reviewed to assess the predictive value for the diagnosis of regional lymph node metastases. Computerized tomography was falsely negative in 5 patients: 2 had metastatic lymph nodes in the renal hilus adjacent to the primary tumor measuring 2 and 2.5 cm., and 3 had micrometastases in nodes of less than 1 cm. In 43 patients enlarged lymph nodes with a diameter of 1 to 2.2 cm. (median 1.4 cm.) were diagnosed on the preoperative scan and this was confirmed at nephrectomy and pathologically. In 18 of these 43 patients (42%) histological study showed metastases of the renal cell carcinoma in the enlarged lymph nodes. In the other 25 patients (58%) the enlarged nodes showed only inflammatory changes and/or follicular hyperplasia. This finding was significantly more frequent in patients with tumor involvement of the renal vein and tumor necrosis (p = 0.0044). We conclude that the sensitivity of preoperative computerized tomography is good for the detection of enlarged lymph nodes in patients with renal cell cancer (95%). However, significant lymph node enlargement frequently may be caused by inflammatory changes, especially in the presence of tumor necrosis. This radiological finding should not be misinterpreted as metastatic disease, unless it has been proved cytologically by fine needle aspiration.

Carcinoma, Renal Cell↗
PubMed1988

The trochlear motoneurons of lampreys (Lampetra fluviatilis): location, morphology and numbers as revealed with horseradish peroxidase.

The cells of origin of the trochlear nerve of Lampetra fluviatilis have been labelled with horseradish peroxidase (HRP) in order to compare the location and morphology of trochlear motoneurons with those of other vertebrates and to gain insight into the phylogenetic changes of the trochlear system. About 126 bipolar and tripolar trochlear motoneuron perikarya are found in a dorsal tegmental position close to the trochlear root. Only approximately 16% of the labelled cells are on the ipsilateral side of the brain, i.e. they lie predominantly contralateral as in gnathostome vertebrates. Dorsally directed dendrites reach the area of lateral-line and retinofugal fibres, and may establish functional contacts. In addition, each motoneuron has a ventral dendrite that extends towards the fasciculus longitudinalis medialis and to the ventral tegmentum. The dendrites branch close to the oculomotor root. Lampreys show a low muscle fibre to motoneuron ratio (4.5:1), i.e., they resemble amniotic vertebrates more than other anamniotic vertebrates. These data demonstrate both closer resemblance and larger differences of cyclostome and gnathostome trochlear motoneurons than previously suggested.

Animals↗
PubMed1987

The development of the amphibian trochlear nucleus. An HRP study.

The quantitative and qualitative development of the trochlear nucleus of salamanders and frogs was studied using horseradish peroxidase (HRP) as a retrograde marker. A higher number of labelled motoneurons significantly declined in later larval stages, presumably by cell death, as in birds and mammals. In agreement with this assumption, HRP-filled apoptotic cells were found in larvae. Many more labelled trochlear motoneurons were found in adult than in larval amphibians, and [3H]thymidine labelling showed postlarval cell production in the area of the trochlear nucleus. Data are discussed in the context of cell death and ongoing cell proliferation.

Ambystoma↗
PubMed1987

The trochlear nerve of amphibians and its relation to proprioceptive fibers: a qualitative and quantitative HRP study.

The cells of origin of the trochlear nerve of urodeles, anurans and gymnophionans were labelled with HRP in order to compare the location and morphology of trochlear motoneurons and to find evidence for sensory fibers in the trochlear nerve of amphibians. Trochlear motoneuron perikarya were found in a ventral tegmental position predominantly on the contralateral side, but an ipsilateral cell was present in some specimens of urodeles and anurans. About 19 motoneurons were labelled in Ambystoma, about 60 motoneurons in Xenopus, and a maximum of 7 cells in Ichthyophis. Decussation of trochlear nerve fibers showed only in Xenopus a highly variable pattern. In urodeles, selective filling of the trochlear nerve labelled in addition to trochlear motoneurons a caudo-medical tectal group of about 20 neurons of the nucleus of the mesencephalic root of the trigeminal nerve. Gymnophionans showed also labelled cells of the mesencephalic trigeminal root in the caudal midbrain close to the trochlear nerve root. In some frogs, a few cells of the mesencephalic trigeminal root were labelled in the caudal tectum and occasionally in the velum medullare anterius. Comparison of the numbers of trochlear nerve fibers with HRP-labelled motoneurons revealed in Xenopus a proportion of 1.2:1, but of 2.7:1 in Ambystoma. However, counting both labelled motoneurons and cells of the mesencephalic trigeminal root resulted in a trochlear nerve fiber to labelled neuron proportion of 1.3:1 in Ambystoma much like in Xenopus. The numbers of superior oblique muscle fibers and of trochlear nerve fibers, but not of HRP-labelled motoneurons, increased significantly with size in Xenopus laevis. We suggest that increased peripheral branching of individual fibers within the trochlear nerve with size rather than differentiation of additional motoneurons takes place in growing postmetamorphic Xenopus. In contrast to other vertebrates studied so far, the trochlear nerve is a mixed nerve in Ambystoma and perhaps in Ichthyophis. Whether this reflects a primitive or a derived condition is at present unclear.

Ambystoma↗
PubMed1986

A multinomial model for estimating the size of a whale population from incomplete census data.

This paper adapts the removal method of population size estimation to the problem of estimating the size of the western Arctic stock of bowhead whales. The whales are counted during their spring migration as they pass two census camps located near Point Barrow, Alaska. Whales seen at the first camp are "removed" from the population of concern to the second camp, where only whales missed by the first camp are counted. If both camps were in operation throughout the migration and if the probability of missing a whale were constant, the removal method would provide a population size estimate based on a trinomial model in which the size of the population would be the number of trials, whales counted by each camp would provide the observed cell totals, and whales missed by both camps would represent an unobserved cell total. Since the probability of missing a whale depends on visibility, we model the population size as the sum of the number of trials of several independent trinomial distributions, each of which represents a particular visibility condition occurring during the census. To account for the fact that watch cannot be maintained at both camps throughout the migration, we derive a confidence interval estimate of the number of trials under a more general model allowing for incomplete observation of totals within particular cells as well as for completely unobserved cells.

Alaska↗
PubMed1981

[Chemotherapy of non-small-cell bronchial cancer with a combination of Cis-diamminedichloroplatinum (II) and VP 16-213].

In a phase II study 40 patients with non-small-cell lung cancer were treated with 100 mg/m2 cis-diamminedichloroplatinum (II) (DDP) i.v. on day 1, combined with VP 16-213 (VP) in a dose of either 80 mg/m2 daily i.v. on days 1, 2 and 3 or 120 mg/m2 daily by mouth on days 3, 4, 5 and 6. The course was repeated every 3 weeks. In 30 evaluable patients, 10 partial remissions were recorded with a median duration of 3 months. Eleven patients had stable disease and 9 showed progression under treatment. Leukopenia was more pronounced with intravenous administration of VP than with oral VP (median leukocyte nadir 2400/mm3 and 3700/mm3 respectively). Two patients had thrombocytopenia under 50,000/mm3. All patients suffered from moderate to marked nausea and vomiting. All patients had alopecia. Nine patients had serum creatinine elevations over 1.4 mg/dl. Six patients with renal toxicity were treated in one institution with incorrectly applied forced diuresis during DDP administration. DDP and VP are an active regimen for remission induction in non-small-cell lung cancer. Due to cumulative and marked gastrointestinal intolerance this regimen cannot be given over prolonged periods of time.

Adenocarcinoma↗
PubMed1981

[Central nervous system metastases in small cell lung cancer].

Forty of 156 patients (26%) with small cell lung cancer developed central nervous system metastases (CNS metastases) in the course of the disease. CNS metastases were found in 8 patients at the time of the initial diagnosis and 32 patients had subsequent CNS involvement. CNS metastases were usually concurrent with disease progression at other sites and became more frequent as survival increased. With a median survival of 6 months in 1973 19% of patients developed CNS metastases as compared to 35% in 1978, when median survival had increased to 9.5 months. The value of prophylactic cranial irradiation is discussed.

Brain Neoplasms↗
PubMed1978

[Bladder carcinoma associated with long-term treatment with cyclophosphamide for multiple myeloma (author's transl)].

A report is presented of a female patient who developed an extensive bladder carcinoma with severe hemorrhaging after many years of treatment with cyclophosphamide for multiple myeloma. The severe hemorrhage could only be controlled by drainage of the urine. The possible causes of the development of a second neoplasia, particularly of urinary bladder carcinoma following long-term therapy with cyclophosphamide, are discussed.

Aged↗