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Biomedical subjects

N Rossi

Publications and source records attributed to N Rossi.

At least 55 records · Page 3Linked to original sources
PubMed1991

The effects of positive end-expiratory pressure on respiratory resistance in patients with the adult respiratory distress syndrome and in normal anesthetized subjects.

We investigated the effects of positive end-expiratory pressure (PEEP) upon respiratory resistance during mechanical ventilation in 21 subjects anesthetized for surgery (normal subjects) and in 11 patients with the adult respiratory distress syndrome (ARDS). We measured tracheal pressure (Ptr) near the end of the endotracheal tube through a 1.5-mm ID catheter and airflow (V) at 0, 5, and 10 cm H2O PEEP (normal subjects) and at 0, 5, 10, 15, and 20 cm H2O PEEP (patients with ARDS). We computed respiratory system static elastance (Estrs), maximal (Rrsmax) and minimal (Rrsmin) inspiratory resistance by the end-inspiratory occlusion method during constant-flow inflation. Rrsmin represents the ohmic respiratory resistance, whereas Rrsmax is Rrsmin plus the additional respiratory impedance caused by the stress adaptation phenomena of the respiratory system tissues and to time constant inhomogeneities between lung units (pendelluft). The difference (Rrsmax - Rrsmin) has been termed DRrs. We also computed expiratory resistance (Rrsexp) at preselected volume (50% of expiration; Rrsexp50) and flow (0.3 L/s; Rrsexp0.3) using the equation: Rrsexp = (Pelrs(t) - Ptr(t]/Flow(t), where elastic recoil pressure (Pelrs) at time t was computed as:Estrs . V(t) + PEEP, in which V(t) is the volume above end-expiratory volume at time t. We found that (1) at PEEP 0, expiratory resistances (Rrsexp50: 7.38 +/- 1.92 versus 5.35 +/- 1.97 cm H2O.L-1.s) and DRrs (3.08 +/- 1.9 versus 1.66 +/- 0.77 cm H2O.L-1.s) were significantly higher in the ARDS group than in the normal group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Pericardial patch angioplasty.

The authors describe the case of a man with severe left coronary ostial stenosis who was treated with direct left main angioplasty with a pericardial patch. This approach may be superior to artery bypass grafting in certain patients.

Coronary Angiography↗
PubMed1991

Maternal anxiety and childbirth.

The repercussions of the emotional state of a pregnant woman on the course of her labour and delivery and on the state of health of the newborn have been the subject of numerous researches which have yielded contrasting results. The present inquiry was carried out on a group of 34 pregnant women, with the aim of examining the relationship between the emotional state of a woman during pregnancy, on the one hand and, on the other, the course of her labour and delivery, her psychological reaction to it, and the birth weight of her baby.

Adult↗
PubMed1990

Replica filter assay of human beta-adrenergic receptors expressed in E.coli.

We have developed a replica filter assay that permits the direct identification of bacterial colonies expressing membrane receptors. E.coli transformed with appropriate phage or plasmid vectors containing human beta-adrenergic receptor cDNAs were grown on LB/agar plates. Bacterial colonies transferred onto nitrocellulose filters showed specific [125I]-iodocyanopindolol binding. beta-adrenergic receptors expressed in bacteria retained their pharmacological properties when transferred onto filters. This strategy, which is considerably simplified and more rapid compared to similar methods based upon expression of receptor genes in eukaryotic cells, may be a useful tool for cloning membrane receptors.

Brain Chemistry↗
PubMed1990

The role of adenosine in HgCl2-induced acute renal failure in rats.

It has been proposed that adenosine mediates the renal hemodynamic changes in acute renal failure (ARF) and that these changes are pathogenic in reducing glomerular filtration rate. Consistently, adenosine-receptor antagonists such as theophylline have been shown to have protective effects in several experimental models of ARF. The present experiments were designed to explore the potential role of adenosine in HgCl2-induced ARF in rats. In isolated perfused rat kidneys, HgCl2 increased adenosine production and induced a concentration-dependent vasoconstriction. However, the vasoconstriction was unrelated to adenosine production and was not antagonized by theophylline. During the initiation phase of HgCl2-induced ARF in intact rats (first 4 h after injection), theophylline failed to reverse the reduction in inulin clearance, and this failure could not be attributed to a loss of vascular responsiveness to adenosine, since N6-cyclohexyladenosine, a receptor agonist, produced a further reduction in inulin clearance. Furthermore, theophylline actually had deleterious effects during the maintenance phase of HgCl2-induced ARF in intact unanesthetized rats, as evidenced by higher mean serum creatinine values in theophylline-injected rather than in saline-injected rats, on both the second and third days after HgCl2 injection. Therefore HgCl2 acutely increases renal adenosine production, but increased adenosine does not mediate acute HgCl2-induced renal vasoconstriction, and adenosine-receptor antagonism does not have protective effects during the initiation or the maintenance phases of HgCl2-induced ARF in rats. These results provide no support for the hypothesis that increased adenosine mediates the hemodynamic changes in HgCl2-induced ARF.

Acute Kidney Injury↗
PubMed1989

Intrapleural bupivacaine v saline after thoracotomy--effects on pain and lung function--a double-blind study.

The effects of intrapleural (IP) bupivacaine on pain, morphine requirement, and pulmonary function were evaluated in 15 patients for 24 hours after thoracotomy. An IP catheter was placed during surgery. Patients were randomized in a double-blind fashion to receive 1.5 mg/kg of 0.5% bupivacaine IP or saline on two occasions, eight hours apart. A standard anesthetic with thiopental, oxygen, isoflurane, and nondepolarizing muscle relaxant was given. Pain was evaluated with a visual analog pain score every hour, and forced vital capacity (FVC), forced expiratory volume one second (FEV1), peak expiratory flow (PF), and forced expiratory flow 25% to 75% (FEF) were measured 1, 2, 4, 8, and 24 hours postoperatively as well as before and 30 minutes after each IP injection. Arterial blood gases were sampled 1, 2, 8, and 24 hours postoperatively. Plasma bupivacaine concentrations were measured in 10 patients 5, 10, 20, 30, 60, 120, and 180 minutes after IP injection. With each IP bupivacaine injection, the pain score and morphine requirement decreased. There was a significant improvement in all pulmonary function tests in the patients receiving bupivacaine, but no change in the saline controls. The analgesic effect was shortlived (two to five hours), possibly because of loss of bupivacaine in the chest drains. No differences were seen between the two groups after the effect of IP bupivacaine had worn off. Plasma bupivacaine levels had a Cmax of 0.44 to 1.50 micrograms/mL, with a Tmax at 5 to 30 minutes with levels well below 2 to 4 micrograms/mL where increasing toxicity is seen.

Aged↗
PubMed1988

Is duplex follow-up cost-effective in the first year after carotid endarterectomy?

Recent reports have suggested that duplex scanning is an ideal method to noninvasively assess the incidence of recurrent carotid stenosis. However, the timing and frequency of the follow-up studies are controversial. In the present study, 150 patients underwent 173 carotid endarterectomy procedures over a 2 year period. In the postoperative period, a total of 210 duplex studies were carried out on 117 carotid arteries. 21.4 percent of the 117 arteries studied had recurrent stenosis of 16 percent or greater at a mean postoperative follow-up of 15.2 +/- 3 months. Recurrent stenoses were detected early after operation; 96 percent were detected at or before 15 months postoperatively. Patients with recurrent stenoses remained stable and had infrequent symptoms. Several risk factors placed the patient at increased risk for recurrent carotid stenosis: presence of contralateral disease (defined as stenosis of 50 percent or greater), use of tacking sutures, and continued smoking in the postoperative period. Although it remains important for researchers to thoroughly investigate the natural history of atherosclerosis of the extracranial carotid artery, including those changes that occur after carotid endarterectomy, our results indicate that frequent duplex scanning in the first postoperative year is unnecessary and is not cost-effective. Duplex follow-up studies 1 and 12 months after carotid endarterectomy are sufficient for assessing the problem of recurrent stenosis in the first postoperative year.

Adult↗
PubMed1988

Mechanism of adenosine receptor-induced renal vasoconstriction in rats.

Adenosine analogues selective for the A1 subclass of adenosine receptors, such as N6-cyclohexyladenosine (CHA), induce vasoconstriction in the isolated rat kidney perfused at constant flow. Presumably, the vasoconstriction is mediated by increased Ca2+ concentration in renal vascular smooth muscle cells, but the mechanism by which A1 adenosine receptor occupation leads to increased Ca2+ is unknown. In the present experiments, the isolated, perfused rat kidney vasoconstricted in response to CHA, to K depolarization, and to BAY K 8644 (a Ca2+ channel agonist). All of these responses were completely blocked by methoxyverapamil, which suggests that CHA, like K depolarization and BAY K 8644, induces renal vasoconstriction by increasing Ca2+ influx through potential operated Ca2+ channels. The mechanism of action of CHA was different, however, in that pertussis toxin treatment blocked the response to CHA without affecting the responses to K depolarization or to BAY K 8644. Therefore, a pertussis toxin-sensitive step must intervene between occupation of A1 adenosine receptors on renal vascular smooth muscle cells and increased Ca2+ influx through potential-operated Ca2+ channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1987

Antagonistic controls regulate copy number of the yeast 2 mu plasmid.

The endogenous 2 mu plasmid of yeast encodes a site-specific recombinase FLP that can cause an amplification of plasmid copy number. Using strains overexpressing 2 mu plasmid proteins from chromosomal constructs to disrupt the normal balance of gene products, we show here that copy number is controlled by regulating the transcript level of FLP. Expression of FLP is negatively regulated over a 100-fold range by the joint action of the plasmid-encoded REP1 and REP2 proteins, which also have a role in plasmid partition. We also show that the product of the fourth plasmid open reading frame D increases FLP expression by relieving the repression caused by REP1 and REP2. This is the first demonstration of a function for this gene, which we call RAF. The transcription of RAF is also repressed by REP1 and REP2 acting together, but requires a higher level for complete inhibition than that required to repress FLP. Copy number is therefore negatively regulated by REP1-REP2 concentration both by direct repression of FLP and indirectly, by control of the positive element, the anti-repressor RAF. We propose that these antagonistic regulatory mechanisms amplify the signal produced by a small fall in copy number.

DNA Nucleotidyltransferases↗
PubMed1986

Studies on host-virus genome relationship in Epstein-Barr virus immortalized lymphoblastoid cell lines.

Five human lymphoblastoid cell lines immortalized in vitro with the B95-8 EBV strain, chosen to have a low number of copies of EBV genome, were examined to detect variations in electrophoretic mobility of viral restriction fragments and in the karyotype. Patterns of mobility detected with different viral probes are always the same as those obtained with fragments from purified virus-plasmidic DNA, with one exception. This "non-plasmidic" pattern occurs with a probe containing the termini of the linear virion DNA and consists in an increase of the molecular weight and in the appearance of more than one band. Cytogenetic studies carried on the same cell populations used as source of DNA, early after immortalization, showed a diploid modal chromosome number and no G banding rearrangements.

Cell Line↗
PubMed1986

Perception of emotions in borderline hypertensive patients and normal subjects.

The ability to recognize the facial expressions of emotions was investigated in 30 borderline hypertensive patients, 16 with high intralymphocytic sodium content (ILSC) and 14 with normal ILSC, and in 34 normotensive matched controls. To this aim, 48 slides with the facial expressions of emotions and with neutral expressions were shown to the subjects by means of a tachistoscope. Two brief questionnaires, the Affective Communication Test and the Dimensions Rating Scale, were used to assess the ability to express emotions and the intensity of emotional experience in the subjects. Results show in borderline hypertensives a difficulty in recognizing emotions, with differences between the two subgroups of patients.

Adult↗