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Biomedical subjects

G Giannini

Publications and source records attributed to G Giannini.

At least 73 records · Page 4Linked to original sources
PubMed1994

High rate of HIV isolation from plasma of asymptomatic patients through polyethylene glycol (PEG) treatment.

The usefulness of traditional methods of HIV plasma titration has been limited by poor detection capacity in the asymptomatic phase of HIV disease. We analyzed plasma samples from asymptomatic seropositive or early symptomatic patients, comparing the classic plasma culture method with the following techniques: phorbol 12-myristate 13-acetate treatment of target cells, centrifugal inoculation of the virus, heat treatment of cultures, addition of monocyte/macrophages to cultures, and polyethylene glycol (PEG) treatment of the plasma. Only PEG treatment significantly increased the percentage of HIV isolation. The increase of HIV isolation after PEG treatment is more evident in patients with higher CD4+ cell counts and those without detectable levels of p24 antigen. In the p24-negative samples, HIV was isolated in 17 of 24 (71%) with PEG treatment versus nine of 24 (37%) with the classic method (p < 0.01). A number of discordant samples were found using the classic and PEG methods. Combining the positive results obtained with either technique, we obtained an overall HIV detection rate of 76%. The increased sensitivity of the combination of PEG and classic methods may allow a wider use of plasma viremia as part of the virological evaluation of anti-HIV drug efficacy in asymptomatic patients.

Cells, Cultured↗
PubMed1993

Excel: a new cell separator in its very first clinical application.

BACKGROUND: The evolution of technology has been one of the most interesting features that has accompanied thrombocytapheresis throughout the years. In this presentation we report on the preliminary results obtained with Excel, a third-generation cell separator that is presently in its early experimental phase. MATERIAL AND METHODS: So far only 15 thrombocytapheresis procedures, 2 of which of the single-needle type, were carried out on 15 healthy donors processing 4 liters of blood (2.8 liters in single needle). RESULTS AND CONCLUSIONS: The results were satisfactory since the average platelet yield was 4.7 x 10(11). The leukocyte contamination was 0.8 x 10(6) and the RBC contamination 0.4 x 10(7). The platelet efficiency per minute was 6.5 x 10(9), and the run time average 72 min. As to the quality of the product the very first results of platelet aggregation, relative to pre-apheresis, were 78% in response to ADP 6 microM; 106 and 102% in response to collagen 4.5 micrograms/ml and ristocetin 1.5 mg/ml, respectively. Essentially no platelet aggregates were found in the platelet products (Wu-Hoak ratio: 0.91).

Adult↗
PubMed1992

Expression of a ryanodine receptor-Ca2+ channel that is regulated by TGF-beta.

Ryanodine receptors (RyRs) are intracellular channels that release calcium ions from the sarcoplasmic reticulum (SR) in response to either plasma membrane depolarization (in skeletal muscle) or increases in the concentration of intracellular free Ca2+ (in the heart). A gene (beta 4) encoding a ryanodine receptor (similar to, but distinct from, the muscle RyRs) was identified. The beta 4 gene was expressed in all tissues investigated, with the exception of heart. Treatment of mink lung epithelial cells (Mv1Lu) with transforming growth factor beta (TGF-beta) induced expression of the beta 4 gene together with the release of Ca2+ in response to ryanodine (but not in response to caffeine, the other drug active on muscle RyRs). This ryanodine receptor may be important in the regulation of intracellular Ca2+ homeostasis.

2-Aminopurine↗
PubMed1990

Relative increase of T cells expressing the gamma/delta rather than the alpha/beta receptor in ataxia-telangiectasia.

In ataxia-telangiectasia, B-cell and T-cell deficiencies are thought to be due to a defect of rearrangements of immunoglobulin and T-cell receptor genes. T cells recognize antigens through two types of CD3-associated receptors: alpha/beta chains on mature cells and gamma/delta chains mostly on immature cells. We studied 10 patients with ataxia-telangiectasia and found that most had a relative increase of circulating T cells bearing gamma/delta receptors rather than alpha/beta receptors, as compared with normal subjects (P less than 0.001). Patients with other immune deficits, including eight with common variable immunodeficiency, one with Wiskott-Aldrich syndrome, two with hyperimmunoglobulinemia E syndrome, and one with severe combined immunodeficiency, had normal ratios of gamma/delta-bearing to alpha/beta-bearing cells. A marked predominance of gamma/delta-bearing T cells was found in a patient with a primary T-cell defect. The relative increase in gamma/delta-bearing T cells in the patients with ataxia-telangiectasia was largely accounted for by cells that reacted with the monoclonal antibody BB3, an apparently distinct subset of T cells that selectively express the C gamma 1 gene product of the T-cell receptor. Although they had normal ratios of gamma/delta-bearing to alpha/beta-bearing T cells, the patients with common variable immunodeficiency had a significant increase (P = 0.01) in the number of T cells expressing C gamma 2 that reacted with the monoclonal antibody delta-TCS-1. We conclude that the increased ratio of gamma/delta-bearing to alpha/beta-bearing T cells in ataxia-telangiectasia may reflect both a recombinational defect that interferes with T-cell and B-cell gene rearrangements and an inability to repair damage to the DNA.

Adolescent↗
PubMed1984

The amino-acid sequence of two non-toxic mutants of diphtheria toxin: CRM45 and CRM197.

The amino-acid sequences of two diphtheria toxin-related, non-toxic proteins, CRM45 and CRM197 , were deduced from the complete sequence of their genes: tox 45 and tox 197. CRM45 lacks the last 149 C-terminal amino-acid residues, but is otherwise identical to diphtheria toxin: a single C----T transition introduces an "ochre" (TAA) termination signal in tox 45, after the codon for threonine-386. A single G----A transition was also found in tox 197, leading to the substitution of glycine-52, present in the wild-type toxin, with glutamic acid in CRM197 . This aminoacid change is responsible for the loss of the NAD:EF2 ADP-ribosyltransferase activity in CRM197 , due most probably to an alteration of the NAD+ binding site.

Amino Acid Sequence↗
PubMed1983

The complete nucleotide sequence of the gene coding for diphtheria toxin in the corynephage omega (tox+) genome.

A segment of corynephage omega (tox+) DNA, containing the gene for diphtheria toxin (tox) was fragmented with restriction enzymes and the fragments cloned into M13 vectors for nucleotide sequence determination. A long open reading frame was shown to encode the tox gene by comparing the predicted amino acid sequence with that of peptides derived from the mature toxin molecule. Analysis of the nucleotide sequence shows RNA polymerase and ribosome binding signals preceding a GTG codon in the open reading frame: if this is the correct starting signal for translation, then a 25 amino acid signal peptide can be predicted for the toxin molecule.

Amino Acid Sequence↗
PubMed1982

Aspects of non-enzymatic glycosylation of serum proteins in relation to different glucose loads.

Non-enzymatic glycosylation of serum proteins (GSP) has been studied in control subjects (n = 10) and diabetic patients (n = 12) during different types of glucose loads. In all cases basal GSP, determined after serum dialysis, gave values which were lower than those found before removing glucose. In the diabetics, moreover, they were significantly higher than in the controls. During OGTT and intravenous glucose infusion prolonged for 5 hours, in both groups, GSP, assayed before dialysis, was found be higher than in basal conditions, while after dialysis values were similar to fasting levels. It can be concluded that also after dialysis, to remove free glucose from sample, GSP is correlated with carbohydrate intolerance but the phenomenon is not induced by either brief hyperglycemic peaks or by high glycemic concentrations maintained for 5 hours.

Adult↗
PubMed1981

Interprofessional education in medical school.

The opinions of entering medical students regarding interprofessional education (IPE), and their reasons, are described in this article. More female than male students favour IPE, 49 as compared to 25%. Students who endorse IPE give different reasons for their position than students who oppose it. The former group refer to increased communication and respect among health professionals, increased knowledge about mutual roles and function, greater equality among members of the health team and improved patient care. The opposing group fear that IPE would lower the quality of education by increasing class size and slow the pace of instruction to accommodate students with limited scientific backgrounds. Students also protest against having to study irrelevant subjects and acquire irrelevant skills. The opposing group is concerned primarily with IPE's effect on medical students; the group in favour is concerned more with the effect on patients and interprofessional relations. It seems that opinions about IPE are part of a basic attitudinal structure that medical students bring with them when they enter medical school. The implications for IPE in medical school are discussed.

Attitude of Health Personnel↗
PubMed1978

Adenylate kinase inhibition by adenosine 5'-monophosphate and fluoride in the determination of creatine kinase activity.

The current methods for the determination of creatine kinase (EC 2.7.3.2) activity are derived from Oliver's method, in which AMP is used to decrease interference by adenylate kinase (EC 2.7.4.3). Recently, Szasz et al. and Rosano et al. described methods in which diadenosine pentaphosphate and fluoride, respectively, are used to reduce this interference. However, diadenosine pentaphosphate does not sufficiently inhibit such activity of hepatic origin, while fluoride alone can only inhibit it at concentrations at which the fluoride tends to precipitate as MgF2. Finally, Szasz et al., the Committee on Enzymes of the Scandinavian Society for Clinical Chemistry and Clinical Physiology, and the German Society for Clinical Chemistry have proposed methods in which both AMP and diadenosine pentaphosphate are used to inhibit adenylate kinase. We have found that by using low concentrations of AMP and fluoride together, we can greatly diminish this interference without significant loss of creatine kinase activity and with no precipitation of MgF2.

Adenosine Monophosphate↗