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Biomedical subjects

S Vogel

Publications and source records attributed to S Vogel.

At least 91 records · Page 5Linked to original sources
PubMed1995

Transcallosal removal of lesions affecting the third ventricle: an anatomic and clinical study.

A series of 54 patients with lesions affecting the third ventricle with a wide range of pathology were operated on by the transcallosal approach. Hydrocephalus was present in 68.5% of all patients, and preoperative shunting was performed in 73.0% of them. Before the partial callosotomy, 16 patients were studied by the use of a cognitive, affective, and behavioral battery, which was repeated 10 and 100 days after the operation. No physiological consequences were ever observed after the partial commissurotomy. The postoperative callosal defect was verified by magnetic resonance imaging. Furthermore, 40 formalin-fixed brains were sectioned to study the variations of the anterior cerebral arteries. On the other hand, magnetic resonance imaging measurements of the corpus callosum in 40 normal subjects were performed to establish a classification system for the corpus callosal area. The results showed a wide variability of the cross-sectional area of the corpus callosum. The differences in the thickness of the truncus were responsible for this variability; the length of the corpus callosum was uniform. This may suggest that subjects with a large corpus callosum may have more interhemispheric connections with higher specialization of each hemisphere and that a smaller number of callosal connections may correlate with more ipsilateral pathways and more independent hemispheres. The results and the clinical as well as anatomical material indicate that the anterior transcallosal route is a safe and feasible alternative in the management of a wide spectrum of pathological lesions within the third ventricle and deserves preference over the transcortical technique.

Adult↗
PubMed1995

Magnetic resonance imaging of a glioblastoma of the optic chiasm. Case report.

Malignant optic glioma causing blindness was difficult to diagnose prior to the introduction of computerized tomography (CT) and magnetic resonance (MR) imaging, because earlier neuroradiological procedures often gave negative results and the clinical symptoms for this entity are not specific. In such cases only a craniotomy or postmortem examination revealed the tumor. The authors found no precise description in the literature of a malignant optic glioma diagnosed with modern imaging methods. They present a patient in whom biopsy results confirmed the CT and MR findings of glioblastoma multiforme of the optic chiasm.

Aged↗
PubMed1995

Pressure versus flow in biological pumps.

The pumps with which organisms move fluids span nearly a ten-million-fold pressure range. As in human technology, positive displacement pumps (osmotic, valve-and-chamber, peristaltic, etc.) are used for high-pressure applications and fluid dynamic pumps (using hydrofoils, cilia, aspirators, etc.) for low pressures. But while pressure capability or system resistance dichotomizes pumps by operative mechanism, the values of a dimensionless pressure-flow index prove more relevant to their biological roles; this index is a ratio of overall pressure drop in the system to pressure drop due to viscous resistance to flow.

Animals↗
PubMed1994

Interpretation bias in responses to ambiguous cues in pain patients.

Pain patients and control subjects responses to ambiguous cues were compared in two separate investigations. In the first, pain patients, control subjects and physiotherapists were asked to produce a list of spontaneous associations to ambiguous cues (such as terminal and growth). To control for mood effects the experiment was repeated with three more groups: Pain patients, osteopaths and a control group. Measures of anxiety and depression were incorporated in the analysis. Results indicate that pain patients systematically produce more pain related associations than the other groups, and that this effect is independent of anxiety and depression levels. The discussion concentrates on the implications of these findings both for the theory of pain processing and for clinical interventions.

Adult↗
PubMed1994

A phase I study of interferon-alpha 2b in combination with interleukin-2 in patients with human immunodeficiency virus infection.

Interferon-alpha (IFN-alpha) can inhibit human immunodeficiency virus (HIV-1) replication and is effective in treating Kaposi's sarcoma; interleukin-2 (IL-2) can increase circulating lymphocytes in HIV-1-infected patients. The safety of combination treatment with recombinant (r)IFN-alpha 2b and IL-2 was evaluated in HIV-1-infected patients with > 200 CD4+ T cells/mm3. A maximal tolerated dose of rIFN-alpha 2b was determined for 17 patients; then they received in combination 3, 6, or 12 x 10(6) IU/day rIL-2, given intravenously over 21 days. Twelve patients ultimately received the combination, 9 for the full 21 days. Significant toxicities included flu-like symptoms, anemia, transaminemia, and depression. Transient increases in CD4+ T cell percentages and spontaneous lymphocyte blast transformation were observed. Quantitative microcultures demonstrate a decline in HIV titers in patients receiving rIFN-alpha 2b (5/9) with a further decline on addition of rIL-2 (7/9). In summary, continuous rIL-2 at 6 x 10(6) IU/day in combination with rIFN-alpha 2b was reasonably tolerated and provided preliminary evidence of immunomodulatory and antiviral activity.

Adolescent↗
PubMed1994

Intrastriatal infusion of lisuride--a potential treatment for Parkinson's disease? Behavioral and autoradiographic studies in 6-OHDA lesioned rats.

The present study examined the effect of chronic intrastriatal infusion of the dopamine receptor agonist lisuride on apomorphine-induced rotational behaviour and on D2-dopamine receptors in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal dopaminergic pathway. The completeness of the lesion of the right ascending nigrostriatal dopaminergic pathway was confirmed by apomorphine-induced rotation and [3H]-mazindol autoradiography. The intrastriatal infusion of lisuride (0.5 microgram/h) into the lesioned striatum for 2 weeks induced an immediate but temporary spontaneous contralateral rotation and a reduction of apomorphine-induced rotation of 47.2% relative to pre-lisuride infusion. The density of D2-receptors in the lisuride-infused striatum was significantly decreased by 40% relative to vehicle-infused 6-OHDA lesioned rats. The level of D2-dopamine receptors returned to normal levels 3 weeks after the termination of lisuride infusion. These results show that the intrastriatal infusion of lisuride reverses the behavioural and D2-dopamine receptor changes present in the 6-OHDA lesion rat model of Parkinson's disease.

Animals↗
PubMed1994

[Tuberculosis of the CNS--once again a current neurosurgical disease].

Tuberculosis is relative uncommon in developed countries. The incidence is still considerable in India, in the Middle East and South America. Neurosurgically important manifestations of tuberculosis are intracranial tuberculomas, tuberculous meningitis with hydrocephalus and tuberculous spondylitis. Therefore experiences in the management of these three kinds of neurotuberculosis are described and an overview of the literature is given. The diagnosis of intracranial tuberculomas is difficult because the symptoms are similar to those of many other types of intracranial tumor and the CT-findings are unspecific. Clinical recognition of neurotuberculosis rests mainly on the evidence of the general disease. A positive skin test supports the diagnosis. The management of tuberculomas enclosed stereotactic biopsy to confirm the diagnosis, medical treatment and surgery. But surgery is only indicated for larger symptomatic mass lesions producing midline shift and severe intracranial hypertension. With antituberculous drugs treated tuberculomas begin to decrease in size within the first two months of therapy. Hydrocephalus is a common complication of tuberculous meningitis. Due to the low incidence the first diagnosis in industrialized countries is a hydrocephalus of unknown origin. The diagnosis of tuberculous meningitis is suspected in any case of subacute meningitis with a CSF profile demonstrating a predominance of lymphocytes, elevated protein value, hypoglycaemia and negative stains for bacterial or fungal organisms, because positive smears for acid-fast bacilli are seldom. Without treatment, tuberculous meningitis is invariably fatal within 4 to 6 weeks. Therefore, when ever tuberculous meningitis is suspected, antituberculous therapy must be started.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Comparative genomic hybridization of human malignant gliomas reveals multiple amplification sites and nonrandom chromosomal gains and losses.

Nine human malignant gliomas (2 astrocytomas grade III and 7 glioblastomas) were analyzed using comparative genomic hybridization (CGH). In addition to the amplification of the EGFR gene at 7p12 in 4 of 9 cases, six new amplification sites were mapped to 1q32, 4q12, 7q21.1, 7q21.2-3, 12p, and 22q12. Nonrandom chromosomal gains and losses were identified with overrepresentation of chromosome 7 and underrepresentation of chromosome 10 as the most frequent events (1 of 2 astrocytomas, 7 of 7 glioblastomas). Gain of a part or the whole chromosome 19 and losses of chromosome bands 9pter-23 and 22q13 were detected each in five cases. Loss of chromosome band 17p13 and gain of chromosome 20 were revealed each in three cases. The validity of the CGH data was confirmed using interphase cytogenetics with YAC clones, chromosome painting in tumor metaphase spreads, and DNA fingerprinting. A comparison of CGH data with the results of chromosome banding analyses indicates that metaphase spreads accessible in primary tumor cell cultures may not represent the clones predominant in the tumor tissue.

Adolescent↗
PubMed1993

Age-related nonrandom chromosomal abnormalities in human low-grade astrocytomas.

We report a cytogenetic investigation of 55 low-grade astrocytomas in 52 patients, 15 children and 37 adults. In addition to numerical aberrations such as trisomy 7 and gonosomal losses, we found structural and/or numerical aberrations of chromosome 1 in eight astrocytomas. There was a striking difference between the rearranged chromosomes in pediatric and adult patients. Whereas the pediatric tumors revealed monosomies 1p with accompanying trisomy 1q, the astrocytomas in adults showed partial or complete monosomies 1q.

Adolescent↗
PubMed1993

[Enteral anastomoses in the area of the upper gastrointestinal tract with the biofragmentable anastomosis ring].

In a prospective study, 184 enteral anastomoses in the upper G1-tract using the biofragmentable anastomosis ring (BAR) Valtrac are described in 136 patients. 43 patients had 2 or 3 BAR in upper GIT, 4 patients one BAR in upper and one BAR in lower GIT and 1 patient had 2 BAR in lower GIT. 152 small bowel-small bowel anastomoses, 23 gastroenterostomies, 2 small bowel-colon and 6 colon anastomoses were created. One insufficiency was seen in a small bowel to small bowel anastomoses and one in a gastroenterostomy. One bleeding occurred in the anastomotic region of a gastroenterostomy. Even in cases of multiple use of the BAR no stenoses occurred. The use of these rings can be recommended beside in colon and small bowel to colon anastomoses also in upper GIT.

Adult↗
PubMed1991

Microphotometric determination of enzymes in brain sections. IV. Isocitrate dehydrogenases.

A polyvinyl alcohol-(PVA) containing incubation medium was adapted for the microphotometric determination (kinetic and end-point measurements) of the activities of NAD- and NADP-linked isocitrate dehydrogenases (ICDHs) in cryostat sections of the rat hippocampus. The following incubation medium is recommended for the quantification of NAD- and NADP- (differences in brackets) ICDHs: 100 mM DL-isocitrate, 10 mM sodium azide, 5 mM (4 mM) nitroblue tetrazolium (NBT), 7 mM NAD (4 mM NADP), 10 mM magnesium chloride, 0.25 mM phenazine methosulfate (PMS), with or without 5 mM ADP (without ADP), 23% PVA in 0.05 M Hepes buffer; the final pH was 7.5. With these incubation media a linear response of the reactions lasted at least 20 min. In kinetic and end-point measurements the same level of activities was demonstrable. The use of NaN3 (as a blocker of the respiratory chain) and PMS (as artificial electron carrier) was indispensible for the transfer of all reduction equivalents in the dehydrogenase reactions to the tetrazolium salt NBT. Furthermore, the activation by magnesium ions and the need of PVA to avoid diffusion artefacts of the loosely bound ICDHs were clearly shown. It is concluded that the quantification of ICDHs in situ could be a valuable tool for neurochemical investigations because ICDHs play a role not only in the substrate flux through the tricarboxylic acid cycle but also in providing alpha-ketoglutarate for the formation of glutamate which is an important amino acid in the brain.

Animals↗
PubMed1991

[Treatment of iatrogenic esophageal perforation].

Between the years 1985 and 1989 11 patients with iatrogenic esophageal perforation were treated at the Department of Surgery at the University of Würzburg. 5 perforations were diagnosed within 24 hours, the others after 1 to 5 days. All patients received a non resective surgical treatment, consisting of excision of the perforated area, primary closure in single suture technique strictly extramucosal and drainage. In addition fibrin glue and a pleural wrap protected the suture. In 55% the postoperative course was completely inconspicuous. Only one patient with a recidive of a gastric cancer with lung and liver metastases, died 11 days after operation of a cervical perforation.

Esophageal Perforation↗
PubMed1990

Modulation of the control of mutagenic metabolites derived from cyclophosphamide and ifosfamide by stimulation of protein kinase A.

The phosphorylation of the 2 major phenobarbital-inducible cytochrome P450 isoenzymes IIB1 and IIB2 was increased in intact hepatocytes by the action of the membrane-permeating cAMP derivative N6,O2'-dibutyryl-cAMP. Under these conditions cyclophosphamide and ifosfamide (which are known to be activated by cytochrome P450 IIB1) were investigated for mutagenicity in Salmonella typhimurium TA1535 and TA100 and for cytotoxicity in TA1535. Cyclophosphamide and ifosfamide were transformed to mutagenic and cytotoxic metabolites by the hepatocytes. The activation of both drugs to mutagens was markedly reduced after pretreatment of the hepatocytes with the membrane-permeating cAMP derivative N6,O2'-dibutyryl-cAMP. Cyclophosphamide and ifosfamide activation were reduced to 51% and 38% of unstimulated controls respectively, when hepatocytes were incubated for 1 h with N6,O2'-dibutyryl-cAMP in the presence of the phosphodiesterase inhibitor theophylline, and Salmonella typhimurium TA1535 was used. A marked reduction in mutagenicity of cyclophosphamide (35% compared with unstimulated controls) was also observed under different experimental conditions, namely after pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP for 1.5 h without theophylline and using Salmonella typhimurium TA100 as target strain. Continued presence of the cytochrome P450 IIB1 and P450 IIB2 inducer phenobarbital in the stimulation medium increased the mutagenicity of cyclophosphamide and led to an even more marked reduction of mutagenicity by pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP and theophylline. In order to investigate whether the observed changes were metabolism-related, the ifosfamide metabolite ifosfamide mustard which does not require metabolic activation by cytochrome P450 was studied under the same conditions. Its mutagenicity was indistinguishable after incubation with N6,O2'-dibutyryl-cAMP-treated or with unstimulated hepatocytes. Also the metabolic formation of cytotoxic metabolites from cyclophosphamide and ifosfamide but not that of ifosfamide mustard was markedly decreased by pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP and theophylline. Thus the stimulation of protein kinase A in intact cells has important consequences for the control of genotoxic and cytotoxic metabolites and represents a fast and short-term regulation of it.

Animals↗
PubMed1989

Binding domains and epitopes in platelet-derived growth factor.

Trypsin treatment of recombinant PDGF-BB from Escherichia coli leads to the liberation of a small carboxy-terminal fragment and two internal segments without dissociating the molecule. The remaining core of 21 kDa retained a considerable binding affinity of 8.4 nM. By use of various peptide fragments obtained from monomeric recombinant PDGF-B, a receptor binding domain was assigned to one of these internal trypsin-sensitive segments. This segment is enriched in charged residues, suggesting mainly hydrophilic interactions with the receptor. Circular dichroism measurements of recombinant PDGF-BB showed a high content of random structure and only a small percentage (less than 10%) of alpha-helical structures. This structure was very rigid since the addition of 70% trifluoroethanol or 1% SDS did not change the circular dichroism spectrum. On the basis of these results, a tentative structure was generated by computer modeling.

Amino Acid Sequence↗
PubMed1989

Red cell oxygen transport in man in relation to gender and age.

P50 values, the O2-partial pressure at 50% O2-saturation of hemoglobin, 2,3-DPG, hematological parameters and the plasma concentrations of sexual hormones were determined in 135 subjects of both sexes aged from 10 to 60 years. P50 was significantly higher in sexually mature women than in men, but did not differ between sexes before puberty and after menopause. In females P50 increased with sexual maturation by about 2 mmHg (0.27 kPa). RBC, Hb and Hct remained unchanged. In males Hb-O2-affinity, RBC, Hb and Hct increased with aging. In sexually mature females 2,3-DPG was significantly higher (2 mumol/gHb) than in males, although before puberty and postmaturity no difference was found. In males, 2,3-DPG increased slightly with maturation although P50 decreased. P50 values (pH = 7.4) correlated positively with red cell 2,3-DPG only when data from all groups were pooled (r = 0.330, P less than or equal to 0.0001). Hb was negatively correlated with P50 (r = 0.221, P less than or equal to 0.01). The data suggest a sex hormone and maturation induced influence in the development of the red cell O2-transport system. Estrogens seem to favour a decrease in Hb-O2-affinity rather than an elevation in O2-transport capacity, whereas androgens do the reverse.

Adolescent↗