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Biomedical subjects

J Fischer

Publications and source records attributed to J Fischer.

At least 379 records · Page 21Linked to original sources
PubMed1988

[Surgical management of frontobasal defects by a transcranial subfrontal approach].

On hand of 43 patients who underwent surgical closure of the rhino-frontobasis because of lesions in this localization (38 frontobasal fractures, 2 encephaloceles, 3 defects after surgery of olfactorius-meningeomas) our experiences as well as indications and techniques of the transcranial-subfrontal approach are reported. As there was quite a high number of patients in this group (n = 23, 53%) who - retrospectively - suffered of at least one severe meningitis, the authors stress their opinion that the indication for surgical procedure should be affirmed as consistently as possible, especially in cases were primary rhino-liquorrheas have stopped and bony defects have not been verified in predelective localizations.

Adolescent↗
PubMed1988

Development of more selective anti-cancer nitrosoureas.

2-Chloroethyl-N-nitrosoureas are highly active anti-neoplastic drugs in clinical use for many years. Therapy with these DNA cross-linking agents is limited by their toxic side effects, cumulative and delayed bone marrow toxicity being the main dose-limiting one. Since the intrinsic anti-tumour activity of the nitrosourea group is very high, coupling to appropriate carrier molecules represents a challenge for target-orientated chemotherapy. Many human tumours contain receptors for steroid hormones. Therefore, 2-chloroethyl-N-nitroso-carbamoyl(CNC)-amino acid derivatives have been developed that are linked to steroid hormones. In the series of oestradiol (E2)-linked analogues CNC-L-alanine-E2-17-ester was significantly superior to other E2-linked congeners and to the unlinked equimolar mixture when tested against hormone-dependent N-methyl-N-nitrosourea-induced mammary carcinoma of the rat. Relevance of E2 receptor contents for therapy with E2-linked drugs is evidenced by loss of superiority of this analogue in hormone-independent mammary carcinomas. Some androgen-linked CNC-amino acids showed substantial affinity to the androgen receptor and in part also to the progesterone receptor. A preliminary study in rat leukaemia L5222 revealed the CNC-L-alanine-dihydrotestosterone-17-ester to be highly active. Studies with hormone-dependent tumour models are under way.

Androgens↗
PubMed1987

[Incidence of lactase deficiency in patients with involution osteoporosis and in normal subjects. Its effect on the nutritional intake of calcium and phosphorus].

The incidence of lactase deficiency, evaluated by means of a lactose absorption test with blood glucose measurements, was compared in a group of 58 women suffering from postmenopausal osteoporosis and a control group of 51 normal women of the same age and ethnic origin. In the patients suffering from osteoporosis, the examination was completed by a glucose-galactose absorption test and in the control group by a hydrogen breath test. The prevalence of lactase deficiency is of approximately the same magnitude in the two groups (25.8% and 33.3% respectively). Dietary investigations showed a calcium intake superior to 1 g per day in only 40% of the osteoporotic patients, this deficiency being more important in cases where lactase deficiency was observed than in those showing normal lactose absorption. The influence of lactose malabsorption on the calcium balance, and the role of the latter in the pathogenesis of osteoporosis, are discussed.

Aged↗
PubMed1987

Synthesis, structure and spectroscopic properties of two models for the active site of the oxygenated state of cytochrome P450 [corrected].

Two dioxygen adducts of thiolato-iron(II) porphyrins, [K(222)][Fe(TPpivP)(SC6HF4)(O2)] 1a and [Na(18c.6)][Fe(TPpivP)(SC6HF4)(O2)] 2 were synthesized by reaction of O2 with five-coordinate, high-spin, cryptated alkali metal thiolato-iron(II) 'picket fence' porphyrinate. They were characterized by visible and infrared spectroscopy: lambda max (log epsilon) = 360 nm (4), 427 nm (4.69), 560 nm (3.69), 610 nm (3.40) for both compounds; v(16O-16O) = 1139 cm-1 in chlorobenzene and fluorobenzene for 1a and 2. Single crystals of composition [K(222)][Fe(TPpivP)(SC6HF4)(O2)].[K(222)](SC6HF4)(C 6H5Cl)(H2O) 1b were obtained by diffusion of pentane/xylene mixtures into chlorobenzene solutions of 1a at -5 degrees C. Single crystals of composition [Na(18c.6)][Fe(TPpivP)(SC6HF4)(O2)] were obtained by slow diffusion of pentane into benzene solutions of 2. Structures of 1b and 2 were studied at 20 degrees C (1b) and -100 degrees C (1b and 2). 1b: space group P2(1)/c (monoclinic), a = 16.806(5) A (1.6806 nm), b = 14.331(4) A (1.4331 nm), c = 52.000(15) A (5.2000 nm), beta = 92.95(2) degrees, V = 12.507 A3 (12.507 nm3), Z = 4, Dcal = 1.28 g.cm-3 (t = 20 degrees C). The final R1 factor was 0.085 for 5238 reflections having I greater than 3 sigma(I). 2: space group P2(1)/c (monoclinic), a = 13.107(3) A (1.3107 nm), b = 27.055(4) A (2.7055 nm), c = 25.029(4) A (2.5029 nm), beta = 96.84(2) degrees, V = 8812 A3 (8.812 nm3), Z = 4, Dcal = 1.18 g.cm-3 (t = -100 degrees C). The final R1 factor was 0.088 for 6587 reflections having I greater than 3 sigma(I). The iron atom is, in both compounds, bonded to the four porphyrinato nitrogens (Np), the sulfur atom of the axial thiolate and one oxygen atom of the axially end-on bonded dioxygen molecule. The average Fe-Np distance found in 1b [1.994(4) A, 0.1994 nm] is not significantly different from that found in 2 [1.993(3) A, 0.1993 nm]. The Fe-S bond length is 2.367(3) A (0.2367 nm) in 1b and 2.365(2) A (0.2365 nm) in 2. The Fe-O1 distances with the oxygen atom of O2 bonded to iron are respectively 1.837(9) A (0.1837 nm) and 1.850(4) A (0.1850 nm). The end-on bonded O2 molecule is disordered in both complexes 1b and 2.(ABSTRACT TRUNCATED AT 400 WORDS)

Binding Sites↗
PubMed1987

Sarcomatoid renal tumors. Clinicopathologic correlation of three cases.

The clinical, light and ultrastructural features of three renal neoplasms demonstrating a sarcomatous appearance on light microscopic examination are reported. At the time of radical nephrectomy, all three tumors displayed aggressive features with capsular invasion and either metastases or invasion of adjacent organs. Ultrastructural examination revealed epithelial features in a pure spindle cell tumor and in a malignant fibrous histiocytoma-like tumor (sarcomatoid renal carcinoma) and smooth muscle differentiation (leiomyosarcoma) in a lesion showing features of malignant fibrous histiocytoma. All three patients died from 1 to 9 months after nephrectomy. Renal tumors with a sarcomatous histologic appearance are aggressive neoplasms that cannot be classified accurately solely by employing light microscopic criteria.

Adult↗
PubMed1987

Tractotomy and partial vertical nucleotomy--for treatment of special forms of trigeminal neuralgia and cancer pain of face and neck.

The therapy of face and neck pain has often been elusive. We attempted to improve the condition of these patients and tried to influence 1. pain of trigeminal neuralgia, where other forms of therapy had failed, 2. pain due to tumours in the distribution of the Vth, IXth and Xth nerve, when all other methods had proved to be unsuccessful, 3. pain due to a traumatic lesion of the Vth nerve after severe injury of the face and 4. pain in the first division of the Vth nerve after herpes zoster infection, when other forms of therapy had failed. After tractotomy the subnucleus caudalis n.V. is partially destroyed. Aim of the partial vertical nucleotomy is the interruption between the first and second neuron of the Vth nerve conveying pain and thermal sensibility, but also of the IXth and Xth nerve, which end in the subnucleus caudalis n.V. as well. Tactile and some thermal sensibility in the face is so retained, and anesthesia dolorosa or keratitis neuroparalytica avoided. Medially of and vertically to the tractotomy a 4-6 mm long incision both cranially and caudally of the tractotomy was made. For the first division of the Vth nerve the nucleotomy is performed on the lateral end of the tractotomy incision. In the patients with cancer of the face and neck a rhizotomy C 1/2 was added. 7 of the 12 patients with trigeminal neuralgia and 3 of the 6 patients with tumors of the face and neck were pain-free. The rest also showed a marked improvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Alternative ultrastructural localization of Dolichos biflorus lectin binding sites in proton secreting parietal cells of mice.

High amount of N-acetyl-D-galactosamine specific lectin binding sites were detected on the canalicular membranes of human parietal cells. Our present model investigations on mice showed that the intracellular distribution of the terminal N-acetyl-D-galactosamine containing glycoprotein highly depends on the actual functional state of the parietal cells. In the normal gastric mucosa 40%-60% of parietal cells react positively after staining with horseradish peroxidase or biotin labelled Dolichos biflorus lectin. Ultrastructurally lectin binding sites occur mainly on the basolateral membrane infoldings in fed animals, while they are present exclusively on the canalicular membranes of fasting mice, suggesting that the alternative appearance of lectin binding sites on the opposite membrane areas of parietal cells is tightly coupled to their main function, to H+ secretion.

Animals↗
PubMed1987

Choosing a pediatric recipient for orthotopic liver transplantation.

Between March 3, 1981, and June 1, 1984, 216 children were evaluated for orthotopic liver transplantation. Of the 216 patients, 117 (55%) had received at least one liver transplant by June 1, 1985. Fifty-five (25%) died before transplantation. The 117 patients who received transplants were grouped according to severity of disease and degree of general decompensation at the time of transplantation. The severity of a patient's medical condition with the possible exception of deep hepatic coma, did not predict outcome following orthotopic liver transplantation. Seventy variables were assessed at the time of the evaluation. Twenty-three of the 70 variables were found to have prognostic significance with regard to death from progressive liver disease before transplantation. These 23 variables were incorporated into a multivariate model to provide a means of determining the relative risk of death among pediatric patients with end-stage liver disease. This information may allow more informed selection of candidates awaiting liver transplantation.

Ambulatory Care↗
PubMed1987

Crystal structure of a snake venom cardiotoxin.

Cardiotoxin VII4 from Naja mossambica mossambica crystallizes in space group P61 (a = b = 73.9 A; c = 59.0 A) with two molecules of toxin (molecular mass = 6715 Da) in the asymmetric unit. The structure was solved by using a combination of multiple isomorphous replacement and density modification methods. Model building and least-squares refinement led to an agreement factor of 27% for a data set to 3-A resolution prior to any inclusion of solvent molecules. The topology of the molecule is similar to that found in short and long snake neurotoxins, which block the nicotinic acetylcholine receptor. Major differences occur in the conformation of the central loop, resulting in a change in the concavity of the molecule. Hydrophobic residues are clustered in two distinct areas. The existence of stable dimeric entities in the crystalline state, with the formation of a six-stranded antiparallel beta sheet, may be functionally relevant.

Amino Acid Sequence↗
PubMed1987

Functional properties of primitive and definitive red cells from chick embryo: oxygen-binding characteristics, pH and membrane potential, and response to hypoxia.

We compare properties of primitive and definitive red cells in three areas effect of different hemoglobin patterns on oxygen affinity cellular response to hypoxia, and red cell membrane potential and cell pH since during incubation blood pH decreases by 0.5 pH. We find that the first population of definitive red cells has many properties in common with the preceding primitive red cells. The oxygen-binding curves are nearly identical despite the fact that the definitive red cells contain only the adult hemoglobins A and D; in particular, n values greater than 4 are recorded in the upper saturation range. Within the definitive red cell population there is a drastic increase in the oxygen affinity between days 7 to 14. Hypoxia causes a series of coordinated changes in definitive but not primitive red cells, involving the phosphate pattern (2,3 DPG, ATP) as well as changes of carbonic anhydrase activity and oxygen affinity. The results suggest that the oxygen pressure controls part of the differentiation program of the definitive cell population and that control is dependent on plasma factors of high molecular weight. The membrane potential of primitive and early definitive red cells is a proton diffusion potential. During development proton conductivity decreases, and at day 16 proton and chloride distribution can be adequately described by the Donnan equilibrium. The linkage between membrane potential and proton distribution allows maintenance of red cell pH at about 7.2, irrespective of external pH, which greatly facilitates the adjustment of embryonic oxygen affinity.

2,3-Diphosphoglycerate↗