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Biomedical subjects

A Clemens

Publications and source records attributed to A Clemens.

15 recordsLinked to original sources
PubMed1992

Vasoactive intestinal polypeptide induces neurogenic contraction of guinea-pig ileum. Involvement of acetylcholine and substance P.

The effect and mode of action of vasoactive intestinal polypeptide (VIP), a peptidergic neuromodulator in the gastrointestinal nervous system, were investigated in isolated muscle strips of the guinea-pig ileum. VIP induced concentration-dependent (20 nM-1 microM) contractions of longitudinal ileal strips. TTX (1 microM), a mixture of atropine (3 microM) and spantide (30 microM), a mixture of atropine (3 microM) and omega-conotoxin GVIA (100 nM), somatostatin (60 nM) and dynorphin (100 nM) abolished the effect of VIP. In most cases a small relaxation became evident. Desensitization to substance P in the presence of atropine prevented VIP-induced contraction. A partial inhibition was observed in the presence of atropine (3 microM), spantide (30 microM), omega-conotoxin GVIA (100 nM), beta-endorphin (265 nM), met-enkephalin (1100 nM) and a mixture of spantide (30 microM) and omega-conotoxin GVIA (100 nM). The action of VIP was not significantly modified by guanethidine (3 microM) or hexamethonium (150 microM). In circular ileal strips VIP (10-300 nM) caused concentration-dependent relaxations through a direct myogenic effect. These results indicate that the VIP produced contractions of the guinea-pig ileum are exclusively neurally mediated and involve a cholinergic as well as a noncholinergic-nonadrenergic (NANC) pathway. It is concluded that besides acetylcholine (Ach) VIP releases the peptidergic transmitter substance P from postganglionic nerve fibers of myenteric plexus. Opioid peptides and somatostatin modulate the activity of cholinergic and peptidegic nerves in the guinea-pig ileum. The release of substance P appears to depend completely on N-type voltage sensitive calcium channels.

Acetylcholine↗
PubMed1992

[Optic neuritis in non-Hodgkin's lymphoma].

Optic neuropathy during non-Hodgkin lymphoma is a late central nervous system complication of unfavourable prognosis. It appears especially with involvement of the bone marrow. A normal cerebrospinal fluid, lack of any beneficial effect of the chemo-corticotherapy and absence of papilledema suggest paraneoplastic, or iatrogenic (radio and (or) chemotherapeutic) neuropathy with conclusive histopathological proof only at autopsy. More frequently, cerebrospinal fluid containing malignant cells, papilledema and a beneficial effect of the chemocortico-therapy suggests malignant infiltration of the optic nerve as occurs in our case. Optic neuropathy during non-Hodgkin lymphoma may exceptionally precede the systemic disease by several years. Early oculomotor involvement suggests meningeal malignant infiltration as found in meningeal carcinomatosis.

Evoked Potentials, Visual↗
PubMed1992

Blindness following paranasal sinus surgery: a report of two cases.

Two cases of blindness following paranasal sinus surgery are presented. The first patient, a 38-year old man, developed a delayed massive haemorrhage, after bilateral sphenoethmoidectomy. This hemorrhage could be stopped by electric cauterisation under endoscopical control. During this reintervention the patient developed total blindness of his right eye, and a restriction of the inferotemporal left visual field. The second patient, a 10-year old girl, developed, after bilateral spheno-ethmoidectomy for isolated sphenoiditis, total blindness of the left eye and paralysis of the ipsilateral extraocular muscles. According to the literature, blindness secondary to paranasal surgery is mainly due to retrobulbar hemorrhage. In the first case blindness was due to a direct cauterisation of the optic nerve, after perforation of the lamina papyracea. In the second case, blindness was probably due to a hemorrhage in the orbital apex.

Adult↗
PubMed1991

Isolation and primary structure of pituitary human galanin, a 30-residue nonamidated neuropeptide.

Galanin (Gal), a 29-amino acid C-terminally amidated neuropeptide, is widely distributed throughout the central and peripheral nervous system. The primary structures of rat and bovine Gals were derived from the cDNA sequences of their precursors. To elucidate the structure of human Gal (hGal), we extracted 280 postmortem pituitaries in trifluoroacetic acid and purified hGal binding activity, by three successive HPLC steps, to homogeneity based on a radioreceptor assay. The primary structure of hGal was determined by automatic Edman degradation to be Gly-Trp-Thr-Leu-Asn-Ser-Ala-Gly-Tyr-Leu-Leu- Gly-Pro-His-Ala-Val-Gly-Asn-His-Arg-Ser-Phe-Ser-Asp-Lys-Asn-Gly-Leu-Thr- Ser-COOH. The structure was confirmed by plasma desorption time-of-flight mass spectrometry, revealing a mass of 3156.1. Compared to the 29-residue porcine, rat, and bovine Gals, hGal uniquely comprises 30 amino acids possessing an additional nonamidated serine residue as C terminus. The nonamidated carboxylic group at the C terminus was proven by synthesis of amidated and nonamidated hGal and by mass spectrometry after selective methylation of all free carboxylic groups. Synthetic hGal possesses full biological activity on isolated rat fundus muscle strips.

Amino Acid Sequence↗
PubMed1991

Routine coronary angiography for effort angina.

OBJECTIVE: To compare the value of exercise testing and coronary angiography in the management of patients with effort angina. DESIGN: A retrospective follow-up study. SETTING: A university teaching hospital. PATIENTS: Four hundred and thirty-four patients with a history of angina, who developed pain or ST segment changes during an exercise test and who were followed-up at up to nine years after their exercise test. INTERVENTIONS: Coronary angiography was offered to patients for disabling angina only. Bypass surgery was generally offered to patients with multiple vessel coronary artery obstruction. MAIN OUTCOME MEASURE: Patient survival. RESULTS: Stepwise regression analysis based on the Cox proportional hazards model indicated that the decision to perform coronary angiography (P less than 0.001) and the amount of ST segment depression on exercise testing (P less than 0.01) were predictors of survival. With ST segment depression set at 1 mm and age set at 53.5 years (both sample median values) the probability of survival at five years was 86% in patients who did not undergo coronary angiography compared with 96% in patients who did undergo angiography. There were eight deaths in 59 patients who did not show any ST segment depression during the exercise test and who were treated medically without coronary angiography. CONCLUSIONS: Coronary angiography is a superior technique to exercise testing for detecting patients with effort angina who are at high risk of premature mortality. Coronary bypass surgery makes a big improvement in the chance of five-year survival in such patients.

Angina Pectoris↗
PubMed1975

[Influence of uremia on the proliferation kinetics of a solid transplantable carcinoma (author's transl)].

UNLABELLED: Previous autoradiographic investigations revealed an impaired regeneration of epithelial tissues in acute experimental uremia. It was the aim of the present study to get information about the effect of uremia on the growth and the proliferation kinetics of a solid tumor (mammary carcinoma HB). MATERIAL AND METHODS: The partly differentiated mammary carcinoma HB (Dr. C. W. Friis/Ry/Denmark) was examined in adult female mice (C3H/Tif). Acute renal failure was induced by ligation of the right ureter and by infarction of two thirds of the left kidney. A group of animals served for urea estimation during the first 7 postoperative days. A sham operation was performed in a control group. A starvation effect was avoided by additional tube feeding. Hemoglobin levels and reticulocytes were estimated in tumour bearing uremic mice and in a control group to get information about anemia in acute uremia. Calculating the tumour volume as a sphere with the geometrical mean of two diameters the tumour doubling time was derived from the growth curve. The autoradiographic experiments started on the 21th day after transplantation of the tumour (= 7th day after experimental uremia and sham operation respectively). The cell cycle was determined by the method of percentage of labeled mitoses. The growth fraction was estimated by continuous labeling method. For details of autoradiographic techniques see Fíaux de Lacroix et al. (1973. RESULTS AND DISCUSSION: During the first 48 hours the blood urea increased to more than 230 mg% and then decreased to a level of about 133 mg% at the 7th postoperative day. The blood urea of control animals was in the range of 50 mg%. Tumor bearing mice revealed an anemia (Hb: 8.1 +/- 1.2 g%, reticulocytes 60.1 +/- 36.5%) but no significant differences in hemoglobin levels and reticulocytes counts could be detected in uremic animals (Hb 9.7 +/- 1.7 g%; reticulocytes 31.4 +/- 11.6%). The growth of the tumour was impaired by uremia. The tumour doubling time was prolonged from 7.5 days in untreated and sham operated animals to 15 days in uremic mice. This was mainly due to a lowered growth fraction (from about 50% to 20%), and on the other hand to a prolongation of the generation time (from 15.5 to 19 hours) mainly caused by a prolonged Tg1-phase. The cell loss factor remained constant (about 81% in every group). Our findings in the transplantable solid tumour of uremic mice were similar to the results observed in the epithelium of the stomach, the intestine and of the skin as well as in erythroblasts especially in regard of the changes of the cell cycle. These observations in various tissues suggest a generally impaired cell proliferation in uremia.

Anemia↗
PubMed1970

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Electrooculography↗