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Biomedical subjects

G Fontana

Publications and source records attributed to G Fontana.

At least 55 records · Page 3Linked to original sources
PubMed1994

Heterocarrier-mediated reciprocal modulation of glutamate and glycine release in rat cerebral cortex and spinal cord synaptosomes.

The effects of glutamic acid (Glu) and glycine (Gly) on each others release were studied using rat brain cortex and spinal cord synaptosomes. Previously taken up [3H]Gly and [3H]D-aspartic acid ([3H]D-Asp) was employed as markers for Gly and Glu/Asp release, respectively. Glu enhanced the release of [3H]Gly (EC50 = 8.4 microM) from cortical synaptosomes. The effect of Glu was not mimicked by the glutamate receptor agonists N-methyl-D-aspartic acid (NMDA), kainic or quisqualic acid. The Glu effect was abolished by the Glu/Asp uptake inhibitor D-threo-hydroxy-aspartic acid and it was Na+ sensitive. D-Asp also increased [3H]Gly release (EC50 = 9.9 microM) and the effect was blocked by the Glu/Asp uptake inhibitor. In contrast to its effect in the cortex, Glu failed to increase the release of [3H]Gly from spinal cord synaptosomes. Gly enhanced the outflow of [3H]D-Asp from rat cerebral cortex and spinal cord synaptosomes (EC50 = 75.0 and 99.5 microM, respectively). Gly was much more potent a releaser of [3H]D-Asp in the spinal cord than in the cortex. The Gly effects were insensitive to strychnine or to 7-Cl-kynurenic acid, antagonists at the two known Gly receptors, but they were strongly Na+ dependent. Our results are compatible with the idea that high-affinity uptake systems specific for Glu/Asp or Gly are colocalized on the same nerve terminal in rat spinal cord and cerebral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Dysplasia and colorectal neoplasms in a group of patients with ulcerative rectocolitis (URC)].

In our Medical Department we examined 74 patients with ulcerative colitis between January 1987 and December 1992. All the patients have been controlled by colonoscopy and multiple rectal byopsies. As started by different studies, the ulcerative colitis is predictive of mucosal dysplasia alterations and colo-rectal carcinoma. Our experience confirms that the occurrence is not so high as reported by some preliminary studies. These results could probably attributed to better diagnostic and therapeutic strategies now available.

Adult↗
PubMed1994

[Urethro-vesical anastomosis after radical prostatectomy and bladder replacement with the Camey II approach].

Owing to its numerous biological characteristics, Tissucol fibrin cement is widely used in general and specialised surgery. In urology it is used on both the renal parenchyma and on the entire urinary tract. The authors report their experience regarding the use of Tissucol in the execution of urethro-vescical anastomosis during radical prostatectomy and cystectomy with orthotopic neovescica according to Camey II. A group of 25 patients were examined of whom 10 with vescical neoplasia and 25 with cancer of the prostate. Anastomosis was always performed using four or five suture stitches in Dexon 2/0 and subsequently sealed with Tissucol. Suture condition was regularly checked using contrastography. The suture only gave way in one case of orthotopic neovescica with consequent urinary fistula; in all the other cases the anastomosis showed a perfect seal in both the short and long term. In the authors' opinion the good immediate result of anastomosis can significantly reduce the postoperative hospitalization.

Aged↗
PubMed1994

[Nosocomial urinary infections. Comparison of experience in two urology centers].

The authors analysed the type and the sensitivity of most common micro-organism causing urinary infections in the urological wards of Savigliano (CN) and Turin. In Savigliano, these data show a remarkable increase in the incidence of Pseudomonas; in the other urological ward the data show an increased incidence of E. coli. In Turin, the bacteria are more sensitive to antibiotics then in Savigliano.

Anti-Infective Agents, Urinary↗
PubMed1994

Evaluation of virulence factors and the adhesive capability of Escherichia coli strains.

Escherichia coli strains recently isolated from adult women with recurrent urinary tract infection (R-UTI) were compared with strains from women with non-recurrent infections (UTI). Haemolysin and mannose-resistant (MR) haemagglutinin were more prevalent in the first group. Using a spectrophotometric technique with biotinylated bacteria, the ability of bacteria to adhere to uroepithelial cells was related to this last character. R-UTI strains are also more resistant to the phagocytic activity of U937 cells. This could relate in vivo to a resistance to mucosal phagocytes, so as to prevent host defence mechanisms.

Adult↗
PubMed1993

Calcium buffering and free Ca2+ in rat brain synaptosomes.

The effects of K+ depolarization and of stimulation by veratridine on apparent cytosolic free Ca2+ ([Ca2+]cyt) and net Ca2+ accumulation were measured in isolated rat brain presynaptic nerve terminals (synaptosomes). [Ca2+]cyt was determined with fura-2, and Ca2+ accumulation was measured with tracer 45Ca. [Ca2+]cyt was approximately 325 nM in synaptosomes incubated in the normal physiological salt solution under resting conditions. When [K+]o was increased from the normal 5 mM to 30 or 50 mM, 45Ca uptake and [Ca2+]cyt both increased within 1 s. Both increases were directly related to [Ca2+]o for [Ca2+]o = 0.02-1.2 mM; however, the increase in 45Ca uptake greatly exceeded the increase in [Ca2+]cyt. With small Ca2+ loads (< or = 100 mumol/L of cell water, equivalent to the Ca2+ entry during a train of < or = 60 impulses), the 45Ca uptake exceeded the increase in [Ca2+]cyt by a factor of nearly 1,000. This indicates that approximately 99.9% of the entering Ca2+ was buffered and/or sequestered within approximately 1 s. With larger Ca2+ loads, a larger fraction of the entering Ca2+ was buffered; approximately 99.97% of the load was buffered with loads of 250-425 mumol/L of cell water. The ratio between the total Ca2+ entry and the increase in [Ca2+]cyt, the "calcium buffer ratio," beta, was therefore approximately 3,500:1. This ratio was somewhat lower than the ratio of total intraterminal calcium: [Ca2+]cyt, which ranged between approximately 7,300:1 and 12,800:1. When the synaptosomes were activated with 10 microM veratridine ([Ca2+]o = 0.2-0.6 mM), 45Ca influx and [Ca2+]cyt increased progressively for approximately 10 s (beta = 2,700:1-3,050:1) and then leveled off.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Glutamic acid and gamma-aminobutyric acid modulate each other's release through heterocarriers sited on the axon terminals of rat brain.

The effects of gamma-aminobutyric acid (GABA) on the spontaneous release of endogenous glutamic acid (Glu) or aspartic acid (Asp) and the effects of Glu on the release of endogenous GABA or [3H]GABA were studied in superfused rat cerebral cortex synaptosomes. GABA increased the outflow of Glu (EC50 17.2 microM) and Asp (EC50 18.4 microM). GABA was not antagonized by bicuculline or picrotoxin. Neither muscimol nor (-)-baclofen mimicked GABA. The effects of GABA were prevented by GABA uptake inhibitors and were Na+ dependent. Glu enhanced the release of [3H]GABA (EC50 11.5 microM) from cortical synaptosomes. Glu was not mimicked by the glutamate receptor agonists N-methyl-D-aspartic, kainic, or quisqualic acid. The Glu effect was decreased by the Glu uptake inhibitor D-threo-hydroxyaspartic acid (THA) and it was Na+ sensitive. Similarly to Glu, D-Asp increased [3H]GABA release (EC50 9.9 microM), an effect blocked by THA. Glu also increased the release of endogenous GABA from cortex synaptosomes. In this case the effect was in part blocked by the (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione, whereas the 6-cyano-7-nitroquinoxaline-2,3-dione-insensitive portion of the effect was prevented by THA. GABA increased the [3H]D-Asp outflow (EC50 13.7 microM) from hippocampal synaptosomes in a muscimol-, (-)-baclofen-, bicuculline-, and picrotoxin-insensitive manner. The GABA effect was abolished by blocking GABA uptake and was Na+ dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Transport System X-AG↗
PubMed1993

[Effects of cyclosporine A on the distribution of a glucose load].

Cyclosporin A (CsA) is an immunosuppressive drug, but it has also a marked action on carbohydrate metabolism. This study was designed to define the role of a single CsA administration in glucose load distribution. Results show that CsA seems to modify glucose load distribution; in fact it influences considerably glycemia and hepatic, cardiac and muscular glycogen levels, particularly after glucose load. The present experiments suggest that CsA has an antagonist action on insulin release elicited by glucose. This effect may be due to a modification of Ca2+ cellular levels in pancreatic beta-cells. Reduction of insulin release may develop a "pharmacologic diabetes" with metabolism deviated towards gluconeogenesis.

Animals↗
PubMed1992

Effectiveness of loading oral flecainide for converting recent-onset atrial fibrillation to sinus rhythm in patients without organic heart disease or with only systemic hypertension.

Sixty-two patients with recent-onset (less than or equal to 1 week) atrial fibrillation (New York Heart Association functional class 1 and 2) were randomized in a single-blind study to 1 of the following treatment groups: (1) flecainide (300 mg) as a single oral loading dose; or (2) amiodarone (5 mg/kg) as an intravenous bolus, followed by 1.8 g/day; or (3) placebo for the first 8 hours. Twenty-four-hour Holter recording was performed, and conversion to sinus rhythm at 3, 8, 12 and 24 hours was considered as the criterion of efficacy. Conversion to sinus rhythm was achieved within 8 hours (placebo-controlled period) in 20 of 22 patients (91%) treated with flecainide, 7 of 19 (37%) treated with amiodarone (p less than 0.001 vs flecainide), and 10 of 21 (48%) treated with placebo (p less than 0.01 vs flecainide). Resumption of sinus rhythm within 24 hours occurred in 21 of 22 patients (95%) with flecainide and in 17 of 19 (89%) with amiodarone (p = not significant). Mean conversion times were shorter for flecainide (190 +/- 147 minutes) than for amiodarone (705 +/- 418; p less than 0.001). No major side effects occurred. At Holter monitoring, a pause of 9.3 seconds was observed in 1 asymptomatic patient treated with flecainide. Phases of atrial flutter with a ventricular rate less than or equal to 150 beats/min were detected before sinus conversion in 1 patient receiving placebo and in 2 receiving flecainide.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Serum pancreatic enzymes in HIV-seropositive patients.

Serum concentrations of trypsin and elastase I were determined in 109 HIV Ab-positive patients (52 asymptomatic HIV-infected patients, 25 with lymphadenopathy syndrome, and 32 with acquired immunodeficiency syndrome) to assess the prevalence of possible pancreatic damage in these patients. Serum trypsin was abnormally elevated in 46 of the 109 patients (42.2%): 19 of the 52 asymptomatic HIV-infected patients (36.6%), 9 of the 25 with lymphadenopathy syndrome (36%), and 18 of the 32 with acquired immunodeficiency syndrome (56.3%). Serum elastase 1 was elevated in 14 of the 109 HIV Ab-positive patients (12.8%): 3 of the 52 asymptomatic HIV-infected patients (5.8%), 3 of the 25 with lymphadenopathy syndrome (12%), and 8 of the 32 with acquired immunodeficiency syndrome (25%). None of the patients with abnormally high serum pancreatic enzyme concentrations had clinically evident pancreatic disease. There was no statistically significant difference in serum levels of trypsin and elastase I between drug addicts and nonaddicts, between alcoholics and nonalcoholics, or between those with cytomegalovirus infection and those without. A significant inverse relationship was found between serum enzyme concentrations and the number of CD4+ lymphocytes. The results of this study show that high levels of serum trypsin and elastase are present in an elevated percentage of patients with acquired immunodeficiency syndrome, suggesting that the pancreas is frequently damaged in this disease. The finding of abnormally high serum enzyme concentrations not only in patients with AIDS, but also in asymptomatic carriers and in patients with lymphadenopathy syndrome suggests an association between HIV infection and the development of pancreatic lesions.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Symptomatic cysts in otherwise normal lungs of children and adults.

The clinical and pathological features of 28 lung cysts resected in the period 1980-1989, excluding those from patients with emphysema elsewhere in their lungs, have been reviewed. In 12 children aged 8 days to 17 years, five cysts were congenital adenomatoid malformations, three were bronchogenic cysts, two were intralobar sequestrations, one was a cystic haemangioma and one resembled the cysts excised from 16 adult patients. This latter group ranged in age from 20 to 62 years and included 11 cigarette smokers and five asthmatics. Twelve of these cysts were intralobar and four were attached by a pedicle to the pleural surface of the lung. All these cysts had a fibromuscular wall showing varying degrees of acute and chronic inflammation. The presence of at least a partial lining of epithelial cells in all the cysts was confirmed using an immunocytochemical marker. The surrounding lung did not show any significant pathology. These cysts are labelled as simple fibromuscular pulmonary cysts. In the childhood cases, a congenital cause could be established in the majority. The pathogenesis of the adult cysts remains unclear. The presence of inflammation in the cyst walls does not necessarily suggest a role for infection, as secondary infection of cysts cannot be ruled out. An aetiological role for local damage due to cigarette smoking or asthma must be taken into consideration.

Adolescent↗
PubMed1992

[Rhabdomyolysis during acute poisoning with drugs and narcotics. Experience with 7 clinical cases].

Numerous and extremely varied conditions (intense muscular activity, ischemia, metabolic and genetic disorders, infections, immunological diseases and toxic causes) may play a role in the genesis of non-traumatic rhabdomyolysis. Over the past years there has been an increased number of reports of forms due to drug or narcotic intoxication. Seven cases of rhabdomyolysis are reported in patients admitted to emergency wards in a state of coma due to heroin overdose (4 cases), cocaine overdose (1 case), carbamazepin (1 case), and tricyclic anti-depressives (1 case). In all cases it was possible to hypothesise a multifactorial pathogenesis of the disease in which other factors, such as acidosis, hypoxia, hypothermia and compression of the muscle mass during coma, were associated with the direct toxic damage caused by the drug. The most frequent complication was acute renal failure. One case of myocardial involvement with non-Q infarction characteristics was also observed.

Adult↗
PubMed1992

[The use of propofol in a female patient predisposed to malignant hyperthermia (central core disease)].

In this paper the Authors describe the anesthetic techniques used for abdominal surgery in a 19 year-old woman with "central-core disease". This uncommon congenital neuromuscular disorder is frequently related to malignant hyperthermia syndrome. Total intravenous anesthesia with the association propofol-fentanyl was well tolerated by the patient. There was no evidence of malignant hyperthermia during the procedure and cardiovascular stability was excellent.

Adult↗
PubMed1992

Anticonvulsant-induced chronic pancreatitis. A case report.

We report the case of a young man suffering from epilepsy who developed chronic calcified pancreatitis after ten years of therapy with the anticonvulsant drugs carbamazepine and phenytoin. Long-term anticonvulsant drug therapy may have a contributory role in the development of chronic pancreatitis by chronic stimulation of cytochromes P-450.

Adult↗
PubMed1991

Cholinergic modulation of [3H]dopamine release from dendrosomes of rat substantia nigra.

Dendrosomes prepared from substantia nigra are able to take up and release [3H]dopamine in a CA(2+)-dependent manner. The Vmax values of [3H]dopamine uptake in substantia nigra dendrosomes was about 5 times lower than that in caudate putamen synaptosomes. The pattern of the K(+)-dependency of the [3H]dopamine release in substantia nigra dendrosomes was significantly different from that found in caudate putamen synaptosomes. The release of [3H]dopamine evoked by 15 mmol/l KCl from superfused dendrosomes was increased in a concentration-dependent manner by acetylcholine. The maximal potentiation produced by acetylcholine was about 40%. The potentiation of [3H]dopamine release by 10 mumol/l acetylcholine was insensitive to mecamylamine but antagonized by atropine and by pirenzepine. The effects of acetylcholine on the release of [3H]acetylcholine from substantia nigra nerve endings was also studied. Exogenous acetylcholine added to the superfusion medium decreased in a concentration-dependent manner the release of acetylcholine. This effect was not antagonized by mecamylamine or pirenzepine but fully antagonized by atropine. The data suggest the existence, in the substantia nigra of the rat, of two distinct muscarinic receptor subtypes regulating respectively dopamine release from dopamine dendrites and acetylcholine release from cholinergic nerve terminals.

Acetylcholine↗