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Biomedical subjects

A Peters

Publications and source records attributed to A Peters.

At least 163 records · Page 9Linked to original sources
PubMed1993

Cortical modules in the posteromedial barrel subfield (Sml) of the mouse.

An antibody to MAP2 was used on sections through the posteromedial barrel subfield (PMBSF) of primary somatosensory cortex to reveal the distributions of cell bodies and dendrites. It was found that apical dendrites of layer VI neurons form irregular bundles or sheets that break up in layer IV, where most of these dendrites form their terminal tufts. In contrast, the apical dendrites of layer V pyramidal neurons form clusters that ascend into layer II/III where they are joined by apical dendrites of the superficial pyramidal neurons. In layer IV the clusters of the layer V apical dendrites are more concentrated in barrel walls than in hollows. Thus, in layer IV the average center to center spacing between the clusters is about 25 microns in the barrel hollows, and about 22 microns in the barrel walls. In part, this differential distribution of the apical dendritic clusters is brought about because the apical dendrites of layer V pyramids beneath the periphery of the barrel hollows arc towards the barrel walls as they pass from layer V into layer IV. Based on previous analyses of the three-dimensional organization of the primary visual areas in the monkey, cat, and rat, it has been proposed that neurons in these cortices are organized into modules that are centered on the clusters of apical dendrites belonging to layer V pyramidal neurons. Mouse PMBSF cortex is composed of similar pyramidal cell modules and the organization of neurons in these modules is similar to that in visual cortex. This suggests that the pyramidal cell modules are fundamental neuronal units that exist throughout the cerebral cortex, and implies that the various functional areas of the cortex in different species are organized according to a common, basic plan.

Animals↗
PubMed1993

The prognosis of patients with stage III melanoma. Prospective long-term study of 286 patients of the Fachklinik Hornheide.

BACKGROUND: Prognostic factors for patients with stage III melanoma are still controversial. METHODS: Two hundred eighty-six patients with solitary cutaneous malignant melanoma of the skin in Stage III (International Union Against Cancer [UICC]) were followed up for as long as 11 years. RESULTS: Patients in risk group pT 4a, pN O (primary tumor thickness of more than 4 mm or invasion of subcutis and absence of regional lymph node metastasis in elective lymph node specimen) have a 5-year survival rate of 72.8%. If regional metastases are excluded clinically (pT 4a, NO), the 5-year survival rate is 62.8%. Patients with regional lymph node metastases have an average 5-year survival rate of 39%, depending mainly on the number of involved lymph nodes and the depth infiltration of the primary tumor. The number of involved lymph nodes reflects the grade of dissemination. It shows a stronger correlation with the prognosis than does the size of metastases. CONCLUSIONS: The authors recommend that revisions of the UICC classification should distinguish Stage IIIA and IIIB based on the presence or absence of regional metastases and that a clearer distinction should be made between regional cutaneous or subcutaneous metastases and regional lymph node metastases.

Adult↗
PubMed1993

Aging and the Meynert cells in rhesus monkey primary visual cortex.

We have assessed the effects of aging on the cell bodies of the large Meynert cells in layers V and VI of the rhesus monkey primary visual cortex by comparing the frequency, size, and cytology of these neurons in three young (5-6 years of age), one middle-aged (12 years of age), and four old monkeys (25-35 years of age). In the young monkeys there is an average of 20.8 Meynert cells beneath 1 mm2 of cortical surface, and in the old monkeys the value is 22.3 cells. The cell bodies of these large pyramidal cells do not become smaller with age, and surprisingly they accumulate only small amounts of lipofuscin. The conclusion is that in the rhesus monkey there is no loss of Meynert cells with age and that aging has little effect on the morphology of the cell bodies of these neurons.

Aging↗
PubMed1993

Prognostic implication of immunodetection of P glycoprotein in Ewing's sarcoma.

Increased expression of P glycoprotein is associated with multidrug resistance in many cell lines. P glycoprotein has been detected in different human tumors. To assess the implication of multidrug resistance in the prognosis of Ewing's sarcoma the expression of P glycoprotein was studied immunohistochemically in pre- and post-therapeutic tumor tissues of 21 cases treated according to the CESS 81 or 86 protocol. The response to chemotherapy was evaluated histologically. Formalin-fixed, paraffin-embedded and fresh frozen sections were immunostained with a monoclonal antibody to P glycoprotein, clone JSB 1, using the double APAAP method. P glycoprotein was detected in 12 cases of 21 (57%) in either pre- or postchemotherapy tumor tissues. From the 21 cases 8 revealed a good morphological response to chemotherapy (33%); 10 of the 13 non-responders were positive for P glycoprotein (77%), but only 2 of the 8 responders (25%). The difference was statistically significant (P < 0.05). Comparing P glycoprotein expression with the clinical outcome, we found that 7 of 12 positive cases had died (58%). From the negative cases only 3 of 9 had died (33%). However, judged by the Kaplan Meyer life tables, these data were not significant. In conclusion our results suggest that the immunodetection of P glycoprotein indicates a poor response to chemotherapy and probably a bad clinical outcome for Ewing's sarcoma patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

[Suspected vaccination complications or atypical vaccination course. Diagnostic assessment of 58 vaccine recipients].

The "list of recommended vaccinations" of the regional Ministries of Health is the legal basis for routine vaccination programmes in each region of Germany; the recommendations of the Federal Commission on Vaccinations, "STIKO", are not legally binding. These programmes of the different regions provide legal grounds for determining claims for damage against a vaccinating doctor. In cases of damage, the Ministry of Health is liable for the damage to a patient caused by a recommended vaccination. Irrespective of these clear and comprehensive legal provisions, in case of an atypical course the patient is entitled to careful diagnosis of the complaint and appropriate medical treatment. However, later claims by the patient for damage can only be decided correctly if the necessary diagnostic data have been carefully collected at the acute stage of the disease. In our 58 patients suffering from atypical vaccination courses or suspected complications, we were able to show in each case that the symptoms are the result of interference by infectious diseases or that there was some other clear diagnosis; in no case did we find that the vaccination had caused disease or permanent damage.

Adolescent↗
PubMed1993

Potter sequence due to renal aplasia and postaxial hexadactyly. A distinct entity?

Report on a prematurely born female with the Potter sequence, postaxial hexadactyly of both hands, and bilateral short metacarpals I. Autopsy findings included severely hypoplastic lungs, bilateral renal aplasia as well as aplasia of the vagina and uterus. Chromosomes were normal (46,XX). Similar--though not identical--observations have been published by Holzgreve et al. (5), by Bonnet et al. (2), and by Legius et al. (6).

Abnormalities, Multiple↗
PubMed1992

Symmetric synapses formed by callosal afferents in rat visual cortex.

Following an electron microscopic examination of 437 degenerating terminals of callosally projecting axons in layer II/III at the 17/18a border, it has been found that some of these terminals form symmetric synapses with dendritic shafts (1.83%), pyramidal cell bodies (1.37%) and dendritic spines (0.46%). The remainder of the axon terminals (96.33%) form asymmetric synapses, mainly with dendritic spines although a few form synapses with dendrites. These results suggest that in the rat visual cortex the corpus callosum is a source of both inhibitory and excitatory input to the contralateral hemisphere.

Afferent Pathways↗
PubMed1992

Axon terminals on Betz cell somata of area 4 in rhesus monkey throughout adulthood.

Previous work in our laboratory demonstrated an age-related decline in the size of Betz cell somata in cortical area 4 of the adult rhesus monkey brain. The present study was conducted to determine whether changes might also occur in the axon terminals upon these cortical cells. Tissue from area 4 was collected from seven rhesus monkeys and prepared for electron microscopy. The ages of the monkeys ranged from 5 to 35 years, covering the entire adult life span of this species. A total of 140 Betz cell profiles (20 per monkey) were examined. Measurements of these profiles confirmed our earlier finding of a decline in the perimeters of Betz cell somata with advancing age. The 1,540 axon terminals upon these cells, however, remained unchanged in size and length of membrane apposition, as well as in their number of mitochondria throughout the adult life (greater than or equal to 5 years) of the rhesus monkey. In addition, the total number of axon terminals on Betz cells did not change with age. Because the axosomatic terminals showed no age-associated changes, the material was used to calculate parametric characteristics of Betz cells and associated terminals. Betz cell somata of the rhesus monkey were estimated to have a mean membrane surface area of 5,700 microns2. Axosomatic terminals on Betz cell somata had a mean appositional area of about 3.33 microns2 and covered about 15% of the somal surface. Thus, on average, each Betz cell appeared to receive approximately 260 axosomatic terminals. There were also some conspicuous age-associated changes in the motor cortex that were not quantified. These included an accumulation of lipofuscin and the presence of a novel inclusion body in the somata of Betz cells. Age-related occurrences in the neuropil included the degeneration of axons and their myelin, membrane-bound holes, and neuritic (senile) plaques.

Aging↗
PubMed1992

Types of callosally projecting nonpyramidal neurons in rat visual cortex identified by lysosomal HRP retrograde labeling.

Callosally projecting neurons, labeled following injection of horseradish peroxidase (HRP) into the 17/18a border of the contralateral hemisphere, have been examined by light and electron microscopy. These neurons exhibit two types of horseradish peroxidase labeling: either a diffuse, Golgi-like labeling, or a granular, punctate labeling. The punctate type of HRP-labeling is the predominant form in nonpyramidal neurons, while pyramidal neurons frequently display either diffuse or punctate labeling. Only punctately labeled neurons have been examined in this study. Light microscopic analyses of 1-microns sections show that in the heavily labeled zone at the area 17/18a border approximately 9% of all of the cells in layer II/III are callosally projecting nonpyramidal cells, and 70% of them are callosally projecting pyramidal cells. Light and electron microscopic examinations indicate that the nonpyramidal neurons are a heterogeneous group which consists of small multipolar neurons, large multipolar neurons, small bipolar neurons, and large bipolar neurons. To investigate the ultrastructural appearance of the punctate HRP labeling, selected neurons have been examined in thin sections. In the electron microscope, the tetramethylbenzidine (TMB) reaction product appears as electron-dense crystals, while the diaminobenzidine (DAB) reaction product appears as dark, electron-dense material which fills the lysosomes. These lysosomes occasionally have a halo of reaction product, but often they are not morphologically distinguishable from dark lysosomes present within neurons from control animals in which the darkening results from staining the thin sections with lead citrate and uranyl acetate. However, labeled neurons possess more dark lysosomes than neurons from control animals. These additional dark lysosomes presumably contain the HRP reaction product visible by light microscopy.

Animals↗
PubMed1992

Elevated lipoprotein(a) levels in patients with acute myeloblastic leukaemia decrease after successful chemotherapeutic treatment.

Twenty-two patients with acute myeloblastic leukaemia (AML) were studied to investigate disease-associated changes in lipid metabolism. Lipoprotein (a) [Lp(a)] levels were found to be elevated at the time of diagnosis (median 23 mg/dl; 41% of patient group had levels greater than 25 mg/dl) and diminished after successful chemotherapeutic treatment in 9 of 10 cases, with a maximum decrease from 56 to 10 mg/dl. In contrast, reduced levels of total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) (medians 137, 87 and 20 mg/dl, respectively) were observed at the time of diagnosis. Cholesterol and HDL levels increased in all 10 and LDL in 9 cases in which complete remission was achieved. These data suggest that the catabolism of LDL-cholesterol might be even more enhanced than assumed to date. Furthermore, it indicates that the Lp(a) level in acute myeloblastic leukaemia is influenced either directly or indirectly by the leukaemic blasts.

Adult↗