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Biomedical subjects

A di Stefano

Publications and source records attributed to A di Stefano.

7 recordsLinked to original sources
PubMed1995

Cytokines in the airway mucosa of subjects with asthma induced by toluene diisocyanate.

To determine the status of activation of lymphocytes and the role of cytokines on the inflammatory response of the bronchial mucosa in toluene diisocyanate (TDI) asthma, we performed a quantitative analysis of bronchial biopsies obtained from 15 subjects with TDI-induced asthma and seven normal control subjects. Markers of activation of lymphocytes (CD25 and Very Late activation Antigen-1, VLA-1) and expression of Tumor Necrosis Factor-alpha (TNF alpha) and interleukin-1 beta (IL-1 beta) were determined by immunohistology in the submucosa. Moreover, expression of adhesion molecules on endothelium of submucosal vessels was assessed. Asthmatic subjects had increased numbers of cells expressing CD25 and VLA-1 compared with the control group (p < 0.05). TNF alpha and IL-1 beta immunoreactivity was increased in asthmatics compared with control subjects (p < 0.01), whereas the expression of adhesion molecules, ICAM-1 and E-selectin, on vascular endothelium was not significantly different. No significant differences in the morphologic quantifications were observed between the asthmatics who had biopsies taken 2 d after TDI challenge (n = 7) and those with longer interval (21 +/- 8 d) between TDI challenge and biopsy (n = 8), suggesting that the increase in CD25, VLA-1, TNF alpha, and IL-1 beta was not due to an acute effect, but could be considered a part of the chronic inflammatory process of the airways. We conclude that the inflammatory response of the airways in TDI-induced asthma is characterized by persistent activation of lymphocytes and by chronic expression of proinflammatory cytokines.

Adult↗
PubMed1993

Hormonal control of renal magnesium handling.

In the kidney, the main site of magnesium transport is the thick ascending limb of Henle's loop which reabsorbs about 70% of filtered magnesium. In the mouse and rat, this reabsorption takes place essentially in the cortical portion of the thick ascending limb (cTAL). In the medullary portion (mTAL) the transport is not significantly different from zero, irrespective of the voltage, whereas in the cTAL, it is exclusively voltage-dependent. In the cTAL, up to six hormones (including PTH) or agonists can stimulate Mg transport. They are totally inactive in the mTAL. The data obtained in the mouse cTAL indicate that the hormone-dependent increases in magnesium transport result from two synergistic effects: (1) a rise in the transepithelial voltage and (2) an increase in the permeability to magnesium of the paracellular shunt pathway.

Absorption↗
PubMed1991

[Role of vasopressin in the modifications of renal function during aging].

In the course of aging, the renal concentrating ability is markedly reduced. This defect may result from an inappropriate synthesis of antidiuretic hormone in the central nervous system or may be due to an impaired renal response to vasopressin. The two hypotheses have been studied in vivo in rats and in vitro in mice. The results of these studies indicated that: 1) dehydration induces a comparable release of vasopressin along the hypothalamo-hypophysial axis in 10, 20 and 30 month-old rats; 2) there is no change with age of the number of nephrons, single nephron filtration rate or transport capacity of Henle's loop of cortical nephrons which could account for an impaired renal response to vasopressin; 3) the reduced concentrating ability of the kidney appears to be linked to a decreased response of the medullary thick ascending limb of Henle's loop which in part is responsible for the cortico-papillary gradient of solutes within the kidney.

Age Factors↗
PubMed1991

[Obstructive urethral disease in neonates].

In the past eight years, we observed 23 cases of neonatal urethral obstruction: 15 posterior urethral valves, one urethral polyp, two urethral diverticula, one penile urethra hypoplasia, two syringoceles, one scafoid urethra, one urethral agenesis in Prune Belly syndrome. In most cases a prenatal diagnosis of uropathy had been made by ultrasonography that allowed a faster diagnosis and possibly a long-term better prognosis in those patients in which early treatment reduced postnatal damage. In all patients endoscopic resection was performed under direct view. In 14 of them endoscopic treatment solved the problem, while further surgery on the upper urinary tract was needed in the others. We had no stenotic nor other-short and medium-term complications. The incidence of renal dysplasia is high with posterior urethral valves, while upper urinary tract damages are sensibly less frequent with more distal obstructions.

Diverticulum↗
PubMed1988

Differential effects of ADH on sodium, chloride, potassium, calcium and magnesium transport in cortical and medullary thick ascending limbs of mouse nephron.

The effect of antidiuretic hormone (arginine vasopressin, AVP) on transepithelial Na+, Cl-, K+, Ca2+ and Mg2+ net transports was investigated in medullary (mTAL) and cortical (cTAL) segments of the thick ascending limb (TAL) of mouse nephron, perfused in vitro. Transepithelial net fluxes (JNa+, JCl-, JK+, JCa2+, JMg2+) were determined by electron probe analysis of the collected tubular fluid. Transepithelial potential difference (PDte) and transepithelial resistance (Rte) were measured simultaneously. cTAL segments were bathed and perfused with isoosmolal, HCO3- containing Ringer solutions, mTAL segments were bathed and perfused with isoosmolal HCO3- free Ringer solutions. In cTAL segments, AVP (10(-10) mol.l-1) significantly increased JMg2+ and JCa2+ from 0.39 +/- 0.08 to 0.58 +/- 0.10 and from 0.86 +/- 0.13 to 1.19 +/- 0.15 pmol.min-1 mm-1 respectively. Neither JNa+ nor JCl-, (JNa+: 213 +/- 30 versus 221 +/- 28 pmol.min-1 mm-1, JCl-: 206 +/- 30 versus 220 +/- 23 pmol.min-1 mm-1) nor PDte (13.4 +/- 1.3 mV versus 14.1 +/- 1.9 mV) or Rte (24.6 +/- 6.5 omega cm2 versus 22.6 +/- 6.4 omega cm2) were significantly changed by AVP. No significant effect of AVP on net K+ transport was observed. In mTAL segments, Mg2+ and Ca2+ net transports were close to zero and AVP (10(-10) mol.l-1) elicited no effect. However NaCl net reabsorption was significantly stimulated by the hormone, JNa+ increased from 107 +/- 33 to 148 +/- 30 and JCl- from 121 +/- 33 to 165 +/- 32 pmol.min-1 mm-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Substrate utilization in the isolated perfused cortical thick ascending limb of rabbit nephron.

Isolated segments of cortical thick ascending limbs (cTAL) of rabbit kidney were perfused in vitro and the equivalent short circuit current (Isc) was measured. In a first series all substrates were removed on either side. Isc fell rapidly to 50 +/- 12% after 3 min and to 27 +/- 6% (n = 5) after 10 min. This indicates that in cTAL segments Isc is strictly dependent on the presence of substrates. In series two it was tested what substrates can be utilized by the cTAL segment, and from which epithelial side [bath (b) or lumen (1)] the substrates are taken up. From the 1-side only butyrate (10 mmol X 1(-1) sustained the Isc at 95 +/- 2% (n = 7). All other tested substrates (10 mmol X 1(-1): pyruvate, acetate, beta-OH-butyrate, D-glucose, and L-lactate lead to a marked decline in Isc. From the b-side several substrates (5--10 mmol X 1(-1) sustained the Isc: D-glucose, D-mannose, butyrate, beta-OH-butyrate, acetoacetate, L-lactate, acetate and pyruvate. Other compounds (1--10 mmol X 1(-1): citrate, alpha-ketoglutarate, succinate, glutamate, glutamine, propionate, caprylate and oleate did not sustain Isc. In the third series the mechanism of substrate utilization from the basolateral cell side was studied. It was shown that the Isc is a saturable function of the D-glucose, L-lactate, acetate, pyruvate or beta-OH-butyrate concentration with apparent Km's between 0.05--1.0 mmol X 1(-1). Several known inhibitors of sugar and of anion transport were tested at the bath side: phlorrhizin was without effect. Phloretin (500 mumol X 1(-1) inhibited Isc by 96%, yet its effect was not dependent on the presence of substrates on the b-side since inhibition occurred also if the b-perfusate contained no substrate and Isc was driven by luminal butyrate. Also SITS (5 mmol X 1(-1) exerted only a small inhibitory effect which was not specific since it was also observed with luminal butyrate. alpha-Cyano-m-OH-cinnamate (10 mmol X 1(-1) inhibited the Isc specifically when L-lactate was the bath substrate. Probenecid (1 mmol X 1(-1) had a similar yet less marked inhibitory effect. The D-glucose uptake from the b-side was specifically inhibited by cytochalasin B at 5 X 10(-6) mol X 1(-1). We conclude that the cTAL segment of the rabbit utilizes D-glucose and/or small anions such as pyruvate or L-lactate or acetate to energize salt reabsorption.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗