Search PubMed⌕ Search

Biomedical subjects

B Rossi

Publications and source records attributed to B Rossi.

At least 217 records · Page 12Linked to original sources
PubMed1983

Isolation of impermeable inside-out vesicles from an enriched sarcolemma fraction of rat heart.

Sarcolemmal vesicles isolated from relaxed rat cardiac ventricles were 120-fold enriched in (Na+ + K+)-ATPase and 5'-nucleotidase activities (final recoveries, 50%). The alpha and beta chains of the former enzyme were visualized by the immunological approach. Inside-out sarcolemmal vesicles were isolated by affinity chromatography on immobilized concanavalin A. The yield of membranes was 0.45 mg of protein/g of muscle. The orientation of the unbound vesicles was studied by the increased accessibility of sarcolemma outer face markers (ouabain- and K+-binding sites, 5'-nucleotidase, and sialic acids) with permeability-increasing treatments: freeze-thaw cycles, sodium dodecyl sulfate, methanol, and valinomycin. The total ATP hydrolysis remained constant with a conversion of ouabain-insensitive activity into an ouabain-sensitive one. These agents caused a parallel increase in the ouabain sensitivity, the number of [3H]ouabain-binding sites, the monovalent cation stimulation of ATPase, and the 5'-nucleotidase activity. Valinomycin revealed that most vesicles were sealed to sequestered and exogenous K+. Inside-out vesicles were 80% pure in sidedness and sealing. The affinity chromatography did not affect the (Na+ + K+)-ATPase activity (200 mumol of product/mg of protein/h). This model of sarcolemma vesicles offers a new tool for ion transport studies.

5'-Nucleotidase↗
PubMed1983

Compression of the deep palmar branch of the ulnar nerve: clinical and electromyographic findings after a new method of decompression.

Five cases of compression of the deep palmar branch of the ulnar nerve were operated upon and the hiatus released by subperiosteal removal of the pisiform bone. The clinical and electromyographical results after a minimum follow-up of eight months showed an improvement in all cases. The authors stress the importance of accurate electromyographic examination for a correct preoperative diagnosis.

Adult↗
PubMed1983

Receptor-mediated phosphorylation of the hepatic insulin receptor: evidence that the Mr 95,000 receptor subunit is its own kinase.

Insulin stimulates the phosphorylation of its own receptor. In the work reported here, the kinase activity responsible for the insulin-stimulated phosphorylation of the insulin receptor was localized. In a first approach, partially purified insulin receptors derived from normal rat hepatocytes were immunoprecipitated with antibodies specific for the insulin receptor; thereafter, the immunoprecipitates were incubated with [gamma-(32)P]-ATP in the absence or presence of insulin (1 muM). NaDodSO(4)/polyacrylamide gel electrophoretic analysis of the immunoprecipitates under reducing conditions revealed autophosphorylation of the beta subunit (M(r) 95,000) of the insulin receptor; the alpha subunit (M(r) 130,000) was not phosphorylated. Further, insulin specifically increased 3- to 4-fold the labeling of its own receptor beta subunit, indicating that anti-receptor antibodies precipitate a functional and insulin-stimulable protein kinase that appears to be independent of cyclic AMP and calcium. To localize more precisely the insulin receptor-related kinase activity, we searched for an ATP-binding site on solubilized insulin receptors. By using covalent labeling with oxidized [alpha-(32)P]ATP, a labeled polypeptide with precisely the same electrophoretic mobility as that of the beta subunit of the insulin receptor (M(r) 95,000) was specifically immunoprecipitated with anti-receptor antibodies. Further, its appearance was prevented when the immunoprecipitation was preceded by incubation with unlabeled insulin. In conclusion, we have shown that an insulin-stimulated phosphorylation site and an ATP-binding site coexist on the beta subunit of the insulin receptor. The simultaneous presence of these two sites on the same receptor subunit indicates that the insulin receptor acts as its own protein kinase.

Adenosine Triphosphate↗
PubMed1983

Nyctohemeral pattern of serum LH, FSH and PRL in patients with myotonic dystrophy.

The nyctohemeral pattern of serum luteinizing (LH), follicle-stimulating hormone (FSH) and prolactin (PRL) in eight patients with myotonic dystrophy (MD) was studied. Gonadotropin patterns were classified as adult, pubertal or infantile. Six patients showed an adult pattern, whereas two had a pubertal or infantile pattern. A normal pattern of PRL secretion was found in seven patients and a blunted sleep-related hormonal increase was observed in one. Impaired hypothalamic control of pituitary secretion in MD is proposed as the cause for these findings.

Adult↗
PubMed1983

Measurement of motor conduction velocity with Hopf's technique in myotonic dystrophy.

Hopf's technique was used to measure maximal and minimal motor nerve conduction velocities, and the percentage of fibres with intermediate velocity, in the posterior tibial nerve in patients with myotonic dystrophy. A reduction of maximal and minimal conduction velocities was found. The distribution of fibres with intermediate velocity was nearly identical to that of the control group and the dispersion values were normal. These data do not support the hypothesis that a primary disturbance of the motor neurons is responsible for the muscle changes in myotonic dystrophy. The reduction of the motor nerve conduction velocity, which was an inconstant finding, should not be considered an indication of a neurogenic aetiology of myotonic dystrophy, but only one of the many disorders of a multisystem disease.

Adult↗
PubMed1982

Identification of the segment of the catalytic subunit of (Na+,K+)ATPase containing the digitalis binding site.

Digitalis compounds that are extensively used in the treatment of cardiovascular disorders are known to bind specifically at the extracellular side of (Na+,K+)ATPase. We have recently reported the synthesis of [3H]p- nitrophenyltriazene -ouabain, a derivative of ouabain, which specifically alkylates the catalytic chain of the (Na+,K+)ATPase at a defined region of the sequence. The peptidic segment involved in the binding of digitalis to (Na+,K+)ATPase has been located after mild trypsin treatment of the labeled enzyme. In the presence of 100 mM KCl, tryptic fragmentation results in two peptide fragments of mol. wt. 58 000 and 41 000, respectively. The radioactive probe labeled only the 41 000 fragment indicating that the digitalis binding site is located on the 41 000 domain situated at the N-terminal part of the sequence of the alpha-subunit.

Animals↗
PubMed1981

Measurement of motor conduction velocity with Hopf's technique in the diagnosis of mild peripheral neuropathies.

Hopf's technique was used to measure motor nerve conduction velocity of fibres in the deep peroneal nerve in clinical conditions where damage to the peripheral nervous system was probable. A particular distribution of motor nerve fibre conduction velocity was shown by the analysis of the findings in some of the groups investigated, illustrating the advantages of this method as compared with routine neurophysiological tests.

Adhesives↗
PubMed1980

Affinity labeling of the digitalis receptor with p-nitrophenyltriazene-ouabain, a highly specific alkylating agent.

Three derivatives of ouabain have been synthesized which alkylate the digitalis receptor. These derivatives were formed through reductive amination of p-nitrophenyltriazene (NPT) ethylenediamine to the periodate-oxidized rhamnose moiety of ouabain. The non-covalent binding of the ouabain derivatives (NPT-ouabain, designated I, II, and III) was followed (i) by their ability to inhibit the activity of sodium- and potassium-activated ATPase ((Na+,K+)-ATPase) purified from the electric organ of Electrophorus electricus, (ii) by the binding of [3H]NPT-ouabain I to the enzyme, and (iii) by the inhibition of [3H]ouabain binding with unlabeled NPT-ouabain I. Covalent modification of the digitalis site of (Na+,K+)-ATPase occurs after long periods of time. At pH 7.5 (25 degrees C) the best alkylating derivative, NPT-ouabain I, gives maximum covalent labeling after 6 h. Only the large polypeptide chain (Mr = 93,000) of the purified enzyme is specifically labeled with [3H]NPT-ouabain I while the glycoprotein chain (Mr = 47,000) is not significantly labeled. Labeling of a microsomal fraction of the electric organ with [3H]NPT-ouabain I gave the same type of gel pattern as that observed with the purified enzyme. [3H]NPT-ouabain I was also used to label the digitalis receptor in highly purified axonal membranes and in cardiac membranes prepared from embryonic chick heart. Although the (Na+,K+)-ATPase in both types of membranes has a low affinity for ouabain, [3H]NPT-ouabain I proved to be a very efficient affinity label for the digitalis receptor. In the complex mixture of polypeptides found in these membrane preparations, only a single polypeptide chain having a Mr = 93,000 is specifically labeled by [3H]NPT-ouabain I.

Affinity Labels↗
PubMed1980

[Chronic renal insufficiency. Low-protein diet supplemented with essential amino acids and ketoanalogues].

Conventional conservative treatment of chronic uremia is aimed at reducing protein intake to a minimum level compatible with nitrogen balance. A great progress in this field is represented by a low protein diet associated with some essential aminoacids and ketoanalogues. A group of 20 patients with chronic renal failure at an advanced stage has been studied and good results have been obtained with a low protein diet (0.2 g/kg/24 h vegetable proteins) associated with essential aminoacids and ketoanalogues.

Amino Acids, Essential↗
PubMed1980

Evaluation of twenty-four-hour secretory patterns of growth hormone and insulin in patients with myotonic dystrophy.

Twenty-four-hour secretory patterns of GH and insulin were evaluated in seven patients with myotonic dystrophy. We found an impairment of sleep-related GH secretion and an increase of nocturnal serum insulin levels. There was no correlation between hormonal behavior and severity of disease. It is possible that the observed hormonal dysfunction is related to a multisystem disorder in myotonic dystrophy.

Adult↗
PubMed1979

[Personal clinical and neurophysiological experience in the surgically treated carpal tunnel syndrome].

In 18 cases of carpal tunnel syndrome treated by surgical decompression of the median nerve, a neurophysiological control was performed before and after surgery. In all cases improvement or disappearance of the pain was observed; improvement in motor function was less constant. Control of the median nerve conduction showed that in all cases with preoperative distal latency less than 6 msec. there was a normalization of the nerve conduction after only 3 months. In cases of distal latency over 6 msec, and especially in those with complete motor conduction block, the latency remain within patological limits even 15 months after surgery. This may be explained either by a slower conduction of the regenerated fibres or by a persistent myelinic and axonal damage of the nerve.

Adult↗
PubMed1979

Blink reflexes in posterior fossa lesions.

Blink reflexes obtained by electrical stimulation of the supraorbital nerve and electromyographic recording of the orbicularis oculi muscle proved useful as a preliminary method in diagnosis of lesions of the brainstem and the fifth and seventh cranial nerves, and in differentiating intrinsic lesions of the brainstem from extrinsic ones. It was noted that R1 and R2 reflexes were different in the two types of lesions.

Adolescent↗
PubMed1979

Blink reflexes in severe traumatic coma.

Blink reflexes were studied in 21 patients in coma after severe head injury. Our observations suggest that blink reflexes are a simple, objective, neurophysiological test to evaluate brainstem function. Correlations between these reflexes and the anatomoclinical stanges of coma and the Glasgow coma scale have been established. Presence of the early R1 component shows the integrity of at least a part of the pontine structures. The appearance of the late R2 component is correlated with a better chance of recovery from coma.

Acute Disease↗
PubMed1979

Body perception in athletes and non-athletes.

20 male athletes and 20 control subjects were required to make estimates of the length of their body dimensions and of external comparison objects. Athletes were more accurate in judging body dimensions than comparison objects while the reverse pattern was demonstrated by non-athletes. The results are discussed on the basis of the possible influence of sports activities on body perception.

Adolescent↗