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Biomedical subjects

E Lorenzoni

Publications and source records attributed to E Lorenzoni.

At least 19 recordsLinked to original sources

[Phantom perception and phantom pain].

"Phantom limb" is a well-known phenomenon following loss or amputation of a limb. The limb still seems to be present, although it is no longer there, but the sensation is not associated with pain. Less well-known are the phenomena of autosomatognosis and pain after the loss of other parts of the body such as the genital parts or after partial or complete deafferentiations as in a traumatic transverse syndrome, lesion of the brachial plexus, or lesions of the CNS. Although many hypotheses have been advanced to explain the pathophysiological mechanisms resulting in these phenomena, the pathogenetic fundamentals have not been properly clarified to date. That is also why manifold approaches have evolved to treat phantom limb pain. The authors survey the literature published so far on this subject and report on their own studies. This gives an overall view of the many aspects of autosomatognosis, phantom limb pain, hypotheses on pathophysiology, and the currently employed treatment strategies.

Afferent Pathways↗

Experiences of phantom limb sensations in dreams.

Phantom limb sensations in the waking state and in dreams were examined in 84 limb-amputated patients. These phenomena were divided into complete, reduced, intermittent and nonexisting phantom limb. Common features as well as differences between the phantom limb in the waking state and in dreams were characterized and illustrated by casuistics and dream reports. Thus it was shown that nearly half the patients had the same, whereas the others had a different phantom limb in the waking state and in dreams.

Aged↗

Bryodin, a ribosome-inactivating protein from the roots of Bryonia dioica L. (white bryony).

Bryodin is a strongly basic (pI greater than or equal to 9.5) glycoprotein (neutral sugar content 6.3%) with Mr 30,000, purified from the roots of Bryonia dioica (white bryony). This protein inhibits protein synthesis by a rabbit reticulocyte lysate with and ID50 (concentration causing 50% inhibition) of 0.12 nM (3.6 ng/ml) and has much less effect on protein synthesis by whole cells, with ID50 values ranging from 46 nM to 2.27 microM (1.4-67 micrograms/ml). Bryodin acts by inactivating ribosomes, with a less-than-equimolar ratio, which suggests a catalytic action. Bryodin decreases the number of local lesions induced by tobacco mosaic virus in the leaves of Nicotiana glutinosa. From all its properties, bryodin can be considered to be a ribosome-inactivating protein, similar to those already known [reviews: Barbieri & Stirpe (1982) Cancer Surveys 1, 489-520; Stirpe & Barbieri (1986) FEBS Lett. 195, 1-8].

DNA↗

[Injury of the lateral cutaneous nerve of the thigh. A rare complication following gynecologic surgery].

Femoral nerve impairment subsequent to gynaecological operations is well known. Injury to the N. cutaneous femoris lateralis has not yet been reported either in gynaecological or neurological literature. --At the Department of Obstetrics and Gynaecology, Medical School Hannover, 8 cases of neuropathy of this nerve have been observed from 1973 to 1982. They occurred after vaginal as well as after abdominal operations. The cause of the injury may be a short, but extreme hyperextension of the leg while bringing the patient into lithotomy position. During abdominal operations continuous pressure of a self retaining retractor may lead to the damage. --A similar case however, where the causes mentioned above were absent, revealed that other possibilities must also be considered.

Adult↗

Purification and properties of a new glutathione-dependent thiol:disulphide oxidoreductase from rat liver.

A new GSSG-dependent thiol:disulphide oxidoreductase was extensively purified from rat liver cytosol. The enzymic protein shows molecular weight 40 000 as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, and 43 000 as determined by thin-layer gel filtration on Bio-Gel P-100. The pI is 8.1. This enzyme converts rat liver xanthine dehydrogenase into an oxidase, in the presence of oxidized glutathione. Other disulphide compounds are either inactive or far less active than oxidized glutathione in the enzymic oxidation of rat liver xanthine dehydrogenase. The enzyme also catalyses the reduction of the disulphide bond of ricin and acts as a thioltransferase and as a GSH:insulin transhydrogenase. The enzymic activity was measured in various organs of newborn and adult rats.

Animals↗

Inhibition of protein synthesis in vitro by proteins from the seeds of Momordica charantia (bitter pear melon).

1. A haemagglutinating lectin was purified from the seeds of Momordica charantia by affinity chromatography on Sepharose 4B and on acid-treated Sepharose 6B. It has mol.wt. 115 000 and consists of four subunits, of mol.wts. 30 500, 29 000, 28 500 and 27 000. 2. The lectin inhibits protein synthesis by a rabbit reticulocyte lysate with an ID50 (concentration giving 50% inhibition) of approx. 5 micrograms/ml. Protein synthesis by Yoshida ascites cells is partially inhibited by the lectin at a concentration of 100 micrograms/ml. 3. From the same seeds another protein was purified which has mol.wt. 23 000 and is a very potent inhibitor of protein synthesis in the lysate system, with an ID50 of 1.8 ng/ml. This inhibitor has no effect on protein synthesis by Yoshida cells, and has no haemagglutinating properties. 4. Artemia salina ribosomes preincubated with the lectin or with the inhibitor lose their capacity to perform protein synthesis. The proteins seem to act catalytically, since they inactivate a molar excess of ribosomes. 5. The lectin and the inhibitor are somewhat toxic to mice, the LD50 being 316 and 340 micrograms/100 g body wt. respectively.

Animals↗

Inhibition of protein synthesis in vitro by a lectin from Momordica charantia and by other haemagglutinins.

Protein synthesis by a rabbit reticulocyte lysate is inhibited by the haemagglutinating lectins from Momordica charantia and Crotalaria juncea seeds and from the roe of Rutilus rutilus, and by a commercial preparation of the mitogenic lectin from Phytolacca americana. The haemagglutinins from the seeds of Ricinus communis and of Vicia cracca acquired inhibitory activity after their reduction with 2-mercaptoethanol.

Cell-Free System↗

Modeccin, the toxin of Adenia digitata. Purification, toxicity and inhibition of protein synthesis in vitro.

1. Modeccin, the toxin of Adenia digitata (Modecca digitata), was purified from the roots of this plant by affinity chromatography on Sepharose 4B. 2. This toxin is a protein with mol.wt. 57000, which on treatment with 2-mercaptoethanol can be dissociated into two subunits of mol.wts. 25000 and 32000. 3. Modeccin inhibits protein synthesis in vitro in a lysate of rabbit reticulocytes and in Ehrlich ascites cells; the effect on cells is decreased in the presence of lactose. 4. Dissociation of modeccin into subunits decreases the toxicity to animals and the inhibition of protein synthesis in cells, but enhances the inhibition of protein synthesis in the lysate system.

Animals↗

Studies on the proteins from the seeds of Croton tiglium and of Jatropha curcas. Toxic properties and inhibition of protein synthesis in vitro.

1. Proteins extracted from the seeds of the Euphorbiaceae croton tiglium and Jatropha curcas were separated into three major peaks (I,II,and III) by Sephadex chromatography. 2. The crude protein from both seeds and peaks I and II from Croton and peak I from Jatropha were toxic to mice, to different extents. 3. The crude protein and peak I and peak II from both seeds, inhibited protein synthesis by a reticulocyte lysate; maximum inhibition was exerted by peak II from both seeds. None of these preparations affected protein synthesis in vitro by Ehrlich ascites cells.

Animals↗

[The EEG after frontal and frontobasal skull and brain injury (author's transl)].

Eighty-eight patients with confirmed frontal and frontobasal lesions were examined. The EEG changes were investigated according to type and frequency both after recent trauma and in the later stages (Fig. 1). The general changes showed mainly slight (Fig. 2B) and only rarely severe, dysrhythmias (Fig. 3A) which, however, were frequently associated with paroxysmal outbursts. Focal findings were largely temporal and frontal in the second place (Fig. 2A). All pathological EEG changes showed a tendency to improvement, so that in the late phase they occurred rarely and less severe (Fig. 4). They showed no essential difference from the EEG of uncomplicated craniocerebral traumata. The relations between the EEG and the clinical form of craniocerebral trauma were examined. In contusions of the head the normal EEG was predominant. The pathological EEG was prominent with cerebral concussion and even more so with cerebral contusion. On the other hand, there was no relationship between the EEG and the type of fracture. A significant predominance of pathological EEG was found only in frontobasal fractures with rhinorrhoea. The EEG changes, classified as focal and dysrhythmic, show no statistically significant relationship either to the form of craniocerebral trauma or to the type of fracture. The effect of force coming form in front has apparently been used up chiefly in producing the frontal or frontobasal fractures, and leads to relatively slight cerebral damage. The clinical significance of the EEG does not actually lie in the diagnosis of these injuries, but, as always, in the establishment of the severity and extent of the cerebral lesion and the detection of complications.

Adolescent↗

[The EEG during post-traumatic coma (author's transl)].

With traumatic coma, the underlying pathomorphology may vary and it may not always be possible to establish it. Possible organic lesions are contusions of brain, oedema, intracranial haematoma, fat embolism, or an open brain injury. On the other hand there may be no organic lesions, as for instance in concussion. In every case, the leading clinical symptom is alteration of consciousness. This arises through interference, at some point, with the reticulo-thalamocortical system which is responsible for the regulation of consciousness. Concurrently with the alteration of consciousness, the EEG also shows changes. At the same time, the EEG is affected by the other effects of trauma upon the brain. Becuase of this, this EEG is not exclusively determined by the degree of unconsciousness. The possible causes of traumatic unconsciousness, and of the pathological waves seen in such cases, cannot always be established in clinical medicine, and experimental studies particularly with regard to neurophysiology are required to explain them....

Adult↗

Milk xanthine oxidase type D (dehydrogenase) and type O (oxidase). Purification, interconversion and some properties.

1. The xanthine oxidase of cow's milk, crude or purified, appears as an oxidase (type O), and can be converted almost completely into a NAD(+)-dependent dehydrogenase (type D) by treatment with dithioerythritol or dihydrolipoic acid, but only to a small extent by other thiols. 2. The D form of the enzyme is inhibited by NADH, which competes with NAD(+). 3. The kinetic constants of the two forms of the enzyme are similar to those of the corresponding forms of rat liver xanthine oxidase. 4. Milk xanthine oxidase is converted into an irreversible O form by pretreatment with chymotrypsin, papain or subtilisin, but only partially with trypsin. 5. The enzyme as purified shows a major faster band and a minor slower band on gel electrophoresis. The slower band is greatly reinforced after xanthine oxidase is converted into the irreversible O form by chymotrypsin.

Animals↗