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Biomedical subjects

G Arnold

Publications and source records attributed to G Arnold.

At least 145 records · Page 8Linked to original sources
PubMed1986

Lectin-binding sites in human parathyroid tissue.

The aim of this study was to demonstrate several lectin-binding sites in human parathyroid tissue and to correlate these results with functional activity. The following lectins were tested for binding sites with certain carbohydrates (in parentheses): Arachis hypogea (PNA) (galactose), Ulex europaeus I (UEA) (fucose) and concanavalin A (ConA) (mannose). In addition to normal parathyroids used as controls (13 cases), we examined adenomas associated with a clinical picture of primary hyperparathyroidism of differing severity (31 cases), atrophic glands contralateral to a hyperfunctioning adenoma (7 cases), and secondary (renal) hyperplasia (12 cases). Use of PNA (with and without neuraminidase treatment) and UEA yielded negative staining in normal glands, a wide variety of reactions in adenomas, and frequent dense precipitates in atrophic parathyroids, whereas ConA yielded positive staining in all kinds of parathyroid tissue. Assessment of functional activity of adenomas by clinical parameters (pre-operative serum levels of calcium and parathormone) displayed a significant correlation with the semiquantitative grading of the histochemical reactions after PNA and UEA. Lectin-binding sites in parathyroid chief cells of adenomas are believed to indicate some of the cell structures or products directly involved in the secretory process, including degradation. Although ConA may recognize constituent parathyroid glycoproteins, the binding sites for PNA and UEA are thought to be partially associated with secretory glycoprotein (SP-I), as is known from animal experiments. The positive reaction of the atrophic gland may result from degradation enforced by exposure of primarily non-terminal carbohydrate components.

Adenoma↗
PubMed1986

[Course of left-ventricular contraction in left bundle-branch block and its hemodynamic effects].

The aim of the study was to analyse the left ventricular contraction pattern in left bundle branch block (LBBB), to create experimentally a comparable pattern in animals and to relate this to haemodynamic measurements. In 20 normal subjects and 16 patients with LBBB without coronary heart disease we performed computer-assisted segmental left ventricular wall motion analysis during various systolic periods using two-dimensional echocardiography. The normal subjects showed on average a uniform shortening of all segments in systole; in patients with LBBB, however, asynchronous contractions of various types and intensities were found. Examination of the contraction pattern of each LBBB patient within the confidence range of the normal subjects showed that in 94% there was an abnormally small shortening of one of the sectors at one time in the second part of systole, and in 74% in the region of the interventricular septum. A "septum index" showed significant differences (p less than 0.0025) between LBBB patients and normal subjects. By right ventricular stimulation of the apex (RVA) and the outflow tract (RVOT) we simulated these contraction patterns in 6 dogs. With RVA stimulation the left ventricular contraction pattern was nearly physiological, while with RVOT stimulation the septum movement was paradoxical. With RVA stimulation cardiac output measured by thermodilution was higher (3.45 vs. 3.11 l/min, p less than 0.002) and the left ventricular end-diastolic pressure lower (7.0 vs. 8.0 mm Hg, p less than 0.002) than on RVOT stimulation; aortic pressure and the first derivative of left ventricular pressure did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Ultrastructural investigation of extracellular structures in subcapsular white corrugated cataract (anterior capsular cataract).

Electron microscopic investigations were performed on six extracted lenses from patients undergoing operative treatment of subcapsular white corrugated cataract. The lens capsule itself was unaltered. There was a pronounced extracellular space under the capsule. In this area collagenous aggregations equivalent in size to collagenous fibres and fibrils could be seen. Collagenous microfibrils and delicate microfilaments were also present. The latter could be observed with and without cross-striations. The fibrous structures are distinguished by considerable variations in shape and diameter. The precursor stages of these fibrous materials are produced by myofibroblast-like cells, probably derived from the lenticular epithelium.

Cataract↗
PubMed1985

Myofibrillar degeneration--a common type of myocardial lesion and its selective identification by a modified luxol fast blue stain.

Myofibrillar degeneration is a very common form of myocardial damage. It occurs as a disseminated lesion after various forms of injury (e.g. association with cardiovascular surgery, raised intracranial pressure). As a localized alteration it surrounds the coagulation necrosis of infarcts. The present study introduces a modification of the Luxol Fast Blue (LFB) stain as a specific marker of myofibrillar degeneration. In formalin-fixed and paraffin-embedded myocardium of human autopsies and biopsies two LFB-reaction types are demonstrable: A) irregular blue transverse bands and B) a diffuse blue staining of the entire myocyte. The first type corresponds to the cross band lesion typical of myofibrillar degeneration. By electron microscopy it consists of dense aggregations of disorganized myofilaments. The second form exhibits diffusely LFB-coloured cells and ultrastructurally an irregular felt-like splitting of myofibrils. The latter represents another, until now unrecognized type of myofibrillar degeneration which is not clearly detectable when using other staining methods. Since a coagulation necrosis is only faintly LFB-positive, this method is not suitable for the detection of early stages of infarcts. The obvious advantages of the LFB-method are: detection of type, amount and distribution pattern of myofibrillar degeneration in low-power-views, even if myocytes are cut transversely, high sensitivity, easy handling and reliability. The affinity of damaged cells for the LFB-stain seems to be related to the pathogenesis of myofibrillar degeneration, in which abundant Ca++-influx plays a primary role.

Autopsy↗
PubMed1985

Haemodynamic and antiarrhythmic protective effects of intracoronary perfusion during percutaneous transluminal coronary angioplasty.

In 17 anaesthetized open-chest pigs, experiments were performed to determine if a myocardial protective effect can be obtained by intracoronary perfusion through the dilatation catheter during balloon inflation for percutaneous transluminal coronary angioplasty. Placement of the catheter such that the balloon lay in the middle third of the left anterior descending coronary artery caused a significant deterioration in haemodynamic status prior to balloon inflation, and on 5 occasions led to the development of ventricular fibrillation (VF). Balloon inflation without perfusion for periods of up to 5 min produced further haemodynamic deterioration, and culminated in VF in 4/14 cases. Simultaneous perfusion during balloon inflation (proximal perfusion pressure 900-1200 mmHg), with flow rates of 14.5 ml min-1 for arterial whole blood and 21 +/- 7 ml min-1 for blood diluted with 0.90% NaCl (haematocrit approx. 25%), not only prevented the haemodynamic deterioration but resulted in an improvement compared with values obtained with the catheter in position prior to balloon inflation. In no case did VF occur during 5 min of balloon inflation plus perfusion. The use of diluted blood as the perfusate was not associated with intracatheter thrombus formation, which was sometimes seen as a complication of whole blood perfusion.

Angioplasty, Balloon↗
PubMed1985

Serotonin-induced vasoconstriction in the perfused canine femoral artery can be blocked in vivo by ketanserin.

Serotonin, applied to helical strips of larger vessels such as coronary arteries, acts as a potent vasoconstrictor in vitro. In contrast, in vivo serotonin causes a remarkable decrease in total peripheral resistance. To differentiate the influence of serotonin on resistances of large and small vessels, experiments were done in nine anesthetized dogs. The left iliacal artery was cannulated and blood flow into the femoral artery was kept constant by a roller pump. Mean proximal femoral artery pressure and mean dorsal pedal artery pressure were measured. Pressure gradient (delta P), resistances between proximal femoral artery and dorsal pedal artery (R1), dorsal pedal artery and right atrium (R2), as well as total peripheral resistance were calculated during systemic infusion of 50 micrograms/kg X min serotonin. Serotonin caused a significant increase in delta P and R1 and a decrease in R2 and total peripheral resistance. Pretreatment with 100 micrograms/kg ketanserin abolished the significant change in delta P and R1, whereas the decrease in R2 and total peripheral resistance was not affected. Additional experiments with prazosin showed that alpha-receptors are obviously not involved in the responses observed. Isosorbide dinitrate, which was infused to differentiate passive and active narrowing of vessels, showed a serotoninlike decrease in mean dorsal pedal artery pressure but no change in either delta P or R1. The 5--HT2-serotonergic antagonist ketanserin blocked serotonin-induced constriction of large vessels in vivo but not the dilation of small arteries.

Animals↗
PubMed1985

Effects of serotonin on the cardiopulmonary circulatory system with and without 5-HT2-receptor blockade by ketanserin.

Pulmonary embolism may cause pulmonary hypertension by mechanical obstruction, which might be amplified by vasoconstriction induced by serotonin released from the emboli. The purpose of the present study was to examine whether 5-HT2-receptors are involved in serotonin-induced pulmonary hypertension. Ketanserin was used as 5-HT2-serotonergic antagonist. In nine anesthetized mongrel dogs, the effect of serotonin infusions (10, 50, 100 micrograms/kg . min) on mean pulmonary artery pressure (PAP), pulmonary vascular resistance (PVR), cardiac output (CO), stroke volume (SV), cardiac contractility (dP/dtmax), heart rate (HR), and mean aortic pressure (PAO) was studied with and without treatment by ketanserin (20 and 100 micrograms/kg). Serotonin caused dose-dependent increase in PAP, PVR, CO, SV, and dP/dtmax. A dose of 20 micrograms/kg ketanserin did not affect hemodynamics significantly, whereas 100 micrograms/kg of the compound significantly reduced PAO, TPR, and left ventricular dP/dtmax. The serotonin-induced increases in PAP, PVR, dP/dtmax, CO, and SV were reduced significantly by 100 micrograms/kg ketanserin; the lower dose of ketanserin had only a slight blocking effect. Ketanserin blocks serotonin-induced pulmonary vasoconstriction partly, but it seems also to antagonize the positive inotropic effect of the monoamine.

Animals↗
PubMed1985

[Accessory external ear in the oropharynx].

This report describes the case of a one-day old girl with an accessorial ear lobe in the region of the left soft palate. The girl was referred to us by the children's clinic because of shortness of breath and difficulties in swallowing. On inspecting the cavity of the mouth and the pharynx a pedunculated, ball-shaped, whitish, membranous tumour was identified. The size of the tumour was comparable to a cherry, hanging down from the left velum into the pharynx. It was possible to remove the tumour from its base by using the sling technique. The operation itself did not present any complications. The histological observation revealed a dystopical ear lobe. 13/4 years later, an oto-rhino- laryngological examination diagnosed normal hearing and faculty of speech. The origin as a surplus malformation of the embryological branchial archs is discussed. Due to the morphological result differentiation from a teratoid malformation is possible.

Airway Obstruction↗
PubMed1984

Hemodynamic studies on cimetidine and ranitidine in anesthetized dogs.

The cardiovascular effects of the H2-receptor-antagonists cimetidine and ranitidine have been compared in a randomized double-blind crossover study. The experiments were performed in seven anesthetized mongrel dogs. Cimetidine (200 mg) and ranitidine (50 mg) were infused i.v. for 2 min. The time interval between cimetidine and ranitidine application was always 3 h. The direct comparison of the drug effects on blood pressure shows a significant difference between cimetidine and ranitidine (P less than 0.001). Apart from the sequence of application, cimetidine causes a significant decrease (P less than 0.01) in total peripheral resistance (-271 +/- 50 dyn . s . cm-5) resulting in a decrease in mean blood pressure (-9 +/- 1.1 mmHg). In contrast to cimetidine, none of the recorded parameters are altered significantly by ranitidine. Heart rate, left ventricular end-diastolic pressure, myocardial contractility (dP/dtmaxLV), mean right atrial pressure, mean pulmonary artery pressure, and cardiac output are not affected significantly by either drug. Due to our results it might be concluded that the cimetidine-induced hypotension is mediated by peripheral vasodilation.

Animals↗
PubMed1984

Pressure-induced hypertrophy in hearts of dwarf pigs.

Myocardial DNA-synthesis has been investigated in five adult dwarf pigs by autoradiography, light and electron microscopy 5, 10, 20, 50 and 100 days after banding the ascending aorta. By the banding procedure the mean ventricular pressure in the left heart rose to 40%, reaching an average of 74% at the time of pulse-labelling with 3H-thymidine. Absolute mean heart weights of the hypertrophic hearts reached 165 +/- 25 g in contrast to ten normal hearts with an average of 69 +/- 8 g. The highest labelling indices were found 10 days after onset of pressure-load: 0.46% in the left ventricular wall, 0.35% in the septum and 0.55% in the right ventricular wall. After 20 to 100 days of aortic constriction the labelling indices ranged from zero to 0.25% indicating a continuous slight DNA-synthesis. Electron micrographs demonstrate activation of the rough endoplasmic reticulum and synthesis of myofilamental and myofibrillar structures, changes of the number and size of mitochondria, the nuclear membrane, as well as changes due to hypoxia and degeneration.

Animals↗
PubMed1984

Angiosarcoma in primary lymphedema of the lower extremity--Stewart-Treves syndrome.

After a 20-year latent period an angiosarcoma developed in the edematous leg of a 74-year-old woman with primary lymphedema. A deep venous thrombosis of the leg which further aggravated tissue swelling preceded the appearance of angiosarcoma. Histogenetic classification of the tumor as hemangiosarcoma rather than lymphangiosarcoma was favored by positive immunohistochemical staining for Factor VIII. Despite high amputation and isolated perfusion with hyperthermal cytostatic infusion, she developed local recurrence and distant metastases and died 16 months after operation. Patients with chronic primary or secondary lymphedema are susceptible to angiosarcoma although the overall risk is small.

Aged↗
PubMed1983

Hemispheric lateralization of language in autistic and aphasic children.

The profound language deficit in early infantile autism has led to speculation about the similarities between autistic and language-impaired children. Since aphasia in adults and many children is typically the result of left cerebral hemisphere damage, some researchers have suggested that autistic children also suffer from left hemisphere damage. So far, only indirect or unreliable evidence has been offered in support of this hypothesis. In the present experiment, autistic, language-impaired, and non-language-impaired children were compared on a dichotic listening task designed to overcome some of the deficiencies of earlier research. Language-impaired children were found to exhibit a left ear bias for language material (indicating right hemisphere lateralization for language), whereas the autistic and non-language-impaired children showed the opposite, right ear bias. As the autistic children showed a pattern similar to that of normal children, the present experiment found no evidence for either left hemisphere damage or aphasiclike performance among autistic children. The implications of these findings for understanding the autistic language deficit are explored.

Adolescent↗
PubMed1983

Postnatal DNA-syntheses and mitoses in hearts of dwarf pigs.

Postnatal DNA synthesis and mitoses have been investigated in the heart muscle of 23 dwarf pigs by autoradiography and by light and electron microscopy. During the first weeks the average labelling indices of the myocardium decrease from 3.7 +/- 1.6% to 1.9 +/- 0.6%, while considerable individual variations are observed. The average mitotic indices decrease from 1.0 +/- 0.7% on the tenth to 0.2 +/- 0.1% on the 30th day. The number of two synchronous mitotic figures in the same cell increases from 7.5 to 32.5% in the first postnatal month and causes the mitotic development of nuclear rows. The period between 2 and 8 months after birth is characterized by low DNA synthesis at least in one of the investigated ventricular tissues.

Aging↗
PubMed1983

The bacteriophage P4 alpha gene is the structural gene for bacteriophage P4-induced RNA polymerase.

Two temperature-sensitive mutants of satellite phage P4 which do not synthesize P4 DNA at the nonpermissive temperature have been isolated. One of these phage is mutated in the P4 alpha gene. It complements a P4 delta mutant, but not a P4 alpha amber mutant; both mutants are phenotypically identical to alpha amber mutants in all properties studied. They synthesize P4 early proteins 1 and 2 as well as two additional P4-induced early proteins, 5 and 6, which are described here. P4 late proteins are not synthesized by these mutants and cannot be transactivated by helper phage P2. The mutants are unable to transactivate P2 late proteins from a P2 AB mutant. The P4 RNA polymerase activity which has been suggested to be involved in P4 DNA synthesis is not detected at the nonpermissive temperature. The P4 polymerase activity in partially purified extracts prepared from cells infected with the mutant at the permissive temperature is temperature sensitive. Reduced activity is found in vitro when these extracts are preincubated at 41 degrees C or assayed at temperatures higher than 37 degrees C. Thus, the P4 RNA polymerase is the product of the alpha gene. Temperature shift experiments show that the alpha gene product is required until late in the P4 cycle.

Coliphages↗