Biomedical subjects

R Colombo

Publications and source records attributed to R Colombo.

At least 55 records · Page 3Linked to original sources

PubMed1995

A new approach using local combined microwave hyperthermia and chemotherapy in superficial transitional bladder carcinoma treatment.

For some time hyperthermia, alone or in combination with radiotherapy or chemotherapy, has proved to be a promising method for treating several kinds of solid tumors. After intensive laboratory investigations a new device, based on a microwave source delivering local bladder hyperthermia together with intravesical mitomycin C chemotherapy has been clinically tested as a neoadjuvant approach in 44 patients suffering from superficial cancer of the bladder. The combined approach was administered on an outpatient basis without major complications and with acceptable local toxicity. Endoscopic and histological evaluations proved that combined local hyperthermia and chemotherapy can induce necrosis of transitional tumors. The overall response rate was 90.8%, with 70.4% complete and 20.4% partial, leaving 4 patients (9.2%) nonrespondent. Clinical and histological evaluations have confirmed the feasibility and safety of this combined treatment. Further multicentric studies have been initiated.

Adult↗

PubMed1994

Interactions of microtubule-associated protein MAP2 with unpolymerized and polymerized tubulin and actin using a 96-well microtiter plate solid-phase immunoassay.

A solid-phase immunoassay is used to study the protein-protein interactions between microtubule-associated protein MAP2 and the cytoskeletal proteins tubulin and actin. The assay can be performed on 96-well microtiter plates and can be used to study the interactions with both subunit proteins and their respective polymers, microtubules and microfilaments. The microtiter format allows a large number of samples to be processed, and a number of conditions can be varied. In this solid-phase immunoassay MAP2 bound to microtubules/microfilaments and tubulin dimers/G-actin in a concentration-dependent manner. However, the bound MAP2 was not dissociated from the filaments even at high NaCl concentrations, while simultaneous addition of NaCl diminished MAP2 binding to these proteins. MgCl2 was 1 order of magnitude more efficient in decreasing MAP2 binding compared with NaCl, suggesting that MAP2 may act by "screening" the electrostatic repulsion between tubulin dimers. The role of MAP2 in cross-linking microfilaments and microtubules was also examined. Microtubule/tubulin-bound MAP2 showed a diminished ability to bind to both microfilaments and G-actin, while microfilament/G-actin-bound MAP2 was able to bind efficiently to both microtubules and tubulin dimers.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗

PubMed1994

Tonoplast K+ channels in Arabidopsis thaliana are activated by cytoplasmic ATP.

The effect of ATP on the slow vacuolar cation channels in the tonoplast of suspension-cultured cells of Arabidopsis thaliana L. was examined using the patch clamp technique in the whole-vacuole configuration. The channels were specifically activated by cytoplasmic ATP, other nucleotides (ADP, GTP and nonhydrolizable ATP analogues) being ineffective.

Adenine Nucleotides↗

PubMed1994

Microtubule associated protein MAP1A is an actin-binding and crosslinking protein.

High molecular weight microtubule-associated proteins MAP1A and MAP2 form thin projections from microtubule surfaces and have been implicated in crosslinking microtubules and other cytoskeletal components. We have purified native MAP1A from bovine brain and have studied its interaction with G- and F-actin. Using a solid-phase immunoassay we show that MAP1A binds in a dose-dependent manner to both G-actin and F-actin. Addition of MAP1A to F-actin causes gelation of F-actin and SDS-PAGE analysis shows that MAP1A co-sediments with the gelled network, under conditions where F-actin alone does not pellet. The low apparent viscosity of F-actin is markedly increased in the presence of MAP1A, suggesting that MAP1A can crosslink F-actin. Co-incubation experiments indicate that MAP1A and MAP2 may bind to common or overlapping sites on the actin molecule. The widespread distribution of MAP1A and its interaction with microtubules, actin, and intermediate filaments suggests that it may constitute an important determinant of neuronal and non-neuronal cellular morphology.

Actins↗

PubMed1994

Detubularized sigmoid colon for bladder replacement after radical cystectomy.

During the last 6 years 24 sigmoid colon neobladders were constructed at our institute according to a surgical technique that provides for an optimal spherical configuration of the orthotopic reservoir. All patients underwent radical cystectomy for locally advanced or superficial recurrent bladder cancer. The surgical complication rate was minimal. Mean followup was 38.3 months (range 7 to 70). Patients were evaluated at 9 and 18 months with urodynamic tests. Daytime continence was achieved in 20 of 21 (95.2%) and in 16 of 17 (94.1%) patients, respectively. Nocturnal incontinence was noted in 9 of 21 (42.8%) and 5 of 17 (29.4%) patients. The mean neobladder capacity was 414 cc and 492 cc, respectively. Endoluminal pressure at the maximum reservoir capacity was 31 cm. water (range 23 to 54) and this did not change significantly at 18 months. Minimal post-voiding residual volume was evidenced in all but 1 patient and was maintained at 18 months. Our modified sigmoid colon neobladder is an easy surgical procedure that provides satisfactory total bladder replacement in select patients.

Adult↗

PubMed1994

The accuracy of power-spectrum analysis of heart-rate variability from annotated RR lists generated by Holter systems.

The accuracy of spectral analysis of heart-rate variability performed on annotated RR interval lists obtained from several commercial Holter systems was appraised. Five tape-recorder-based systems (Del Mar 750, Marquette 8000, Oxford Medilog Excel, Remco Cardioline AD 35 and Reynolds Pathfinder PA3) and four solid-state systems (Hewlett Packard 43420B, Marquette Seer, Oxford 6000FD2, Reynolds E-Ram) were considered. Two ECG signals with fixed real morphology but characterized by a different degree of modulation of the RR interval (reduced and normal variability) were fed into the recorders evaluated. The total power and the power in the very low-, low- and high-frequency bands were then estimated on all Holter-generated RR sequences. Spectral analysis was performed by both the autoregressive and fast-Fourier-transform methods. The estimation error of each parameter was statistically characterized and, for tape-recorder-based systems, inferential analysis was used to test for differences between recorders, tapes and times of recording. The centre and dispersion of the estimation error changed markedly from system to system. Some tape-recording systems showed large inter-recorder differences. The degree of spectral distortion was never uniform among selected bands. Solid-state systems performed better than tape-recording ones but both were limited in the accuracy by the quantization of RR interval measurement. The fast Fourier method yielded spectral estimates more stable than the autoregressive method. Our data clearly show that spectral analysis of very low-variability signals may be seriously affected by Holter recording and preprocessing of ECG signals.

Electrocardiography↗

PubMed1994

Epidemiology of urogenital infections caused by Chlamydia trachomatis and outline of characteristic features of patients at risk.

A study of Chlamydia trachomatis infection was conducted in two stages on 15,656 subjects at urogenital clinics of the Faculty of Medicine and Surgery at La Sapienza University in Rome, the S. Anna Hospital in Turin, and the Niguarda Hospital in Milan. The overall incidence of the disease was 6.4% in patients examined throughout the whole study period. The rate of positive cases was 5.8% for the 5270 patients examined up to 1990, and 6.7% for the 10,386 patients examined from 1990 to 1992, showing an increasing trend. There was a much higher positivity rate in men (9.8%) than in women (6.0%); the difference was statistically significant. Of all patients, 60%, were asymptomatic. In symptomatic patients, C. trachomatis was present in 18.5% of cases of non-gonococcal urethritis and in 12.8% of cases of salpingitis. The highest incidence of C. trachomatis infection was in women who had begun sexual activity at an early age, (under 25 years in age), had several sexual partners and used intra-uterine contraceptive devices or spermicides or both.

Adult↗

PubMed1994

Decreased heart rate variability in patients with chronic obstructive pulmonary disease.

To evaluate possible autonomic nervous system (ANS) dysfunction in patients with chronic obstructive pulmonary disease (COPD) in the absence of any hypoxic neuronal damage, we studied 31 patients with COPD patients aged 31 to 68 years (55 +/- 10) and 32 age-matched healthy subjects (control). Respiratory function in the patients was as follows: FEV1 = 52 +/- 8 percent; PaO2 = 71 +/- 14 mm Hg; and PaCO2 = 40 +/- 10 mm Hg. The ANS was assessed by heart rate variability (HRV) in the time domain (SD of mean RR interval) and frequency domain (autoregressive spectral analysis recognizing low [LF] and high [HF] frequency components, vagal and sympathetic related, respectively). Patients and controls were evaluated at rest and during vagal (controlled breathing [CB]) and sympathetic (passive head-up tilt) maneuvers. Patients with COPD showed a depressed global HRV (rest SD = 34 +/- 20 ms vs 45 +/- 15 ms, p < 0.05; tilt SD = 28 +/- 14 ms vs 38 +/- 13, p < 0.01) with a predominant respiratory drive (rest HF = 44 +/- 28 vs 28 +/- 18, p < 0.05; tilt HF 42 +/- 28 vs 16 +/- 12, p < 0.01) as compared with normal subjects. In the control group, vagal and sympathetic responses were in opposite directions following a stimulus, whereas there was no significant HRV response in the COPD group. We conclude that patients with COPD have abnormalities of ANS function, with in particular a depressed HRV response to sympathetic and vagal stimuli.

Adult↗

PubMed1993

[Inguinal hernioplasty by a modified Shouldice technic. Our experience with 350 treated cases].

A statistical analysis of 340 patients operated between 1986 and 1991 for inguinal hernia using the Shouldice procedure are reported by the authors. The majority of patients (60%) treated was between 45 and 65 years old. Two-hundred-eighty-one (82%) were controlled with a mean follow-up of 30 months (range 1-6 years) and was executed with physical examination and a medical questionnaire looking for recurring factors of risk. Hundred-twenty-eight patients (45% of controls) were at the high risk, nevertheless hernia recurrences were not noticed. Postoperative course was uncomplicated in 93% of patients. Early or late loco-regional complications had an incidence of 7%. Local infections and edema were reported in 10 of 22 patients. Acute urinary retention, cephalalgia and hypotension correlated with an anesthesiologic method had an incidence of 5% (17 cases). There were no deaths was pulmonary embolisms. A review of literature was performed and compared with our work. From experience in our Division, Shouldice's hospital technique had a high reliability compared to methods utilized in the previous ten years (Bassini, McNealy, Postemskj, Mugnai-Ferrari), in terms of recurrences.

Adolescent↗

PubMed1993

Alpha-actinin increases actin filament end concentration by inhibiting annealing.

The usual rate of actin polymerization is increased if one starts from actin nuclei. We have noticed that, using alpha-actinin crosslinked actin nuclei, the initial net elongation rate is further enhanced. Also initial net depolymerization rates of alpha-actinin crosslinked F-actin samples are higher than those of controls. These results should imply that alpha-actinin increases the filament end concentration of actin samples. The experiments with barbed and blocking substances (cytochalasin D and gelsolin-actin complex) confirmed such an increase. We have shown that: (1) alpha-actinin does not significantly influence actin polymerization over all; (2) alpha-actinin inhibits the recovery of the filament size in F-actin samples after sonication; and (3) the influence of alpha-actinin on actin filament end concentration is counteracted by tropomyosin. Therefore, we suggest that, upon filament shearing, alpha-actinin crosslinking inhibits the annealing of short actin polymers into longer filaments.

Actinin↗

PubMed1993

Antimicrobial resistance among clinical isolates of Haemophilus influenzae in northern Italy. Collaborative Study on Pediatric Infectious Diseases.

Only scanty data are available on the susceptibility of Haemophilus influenzae in Italy. The in vitro activity of ampicillin, ampicillin-sulbactam, cefaclor, cefuroxime, cefotaxime, chloramphenicol, erythromycin and trimethoprim-sulfamethoxazole against 327 strains of Haemophilus influenzae (55 encapsulated, 272 non-typeable) isolated from adults and children in northern Italy, between January 1984 and December 1989, was compared. Patients were affected by meningitis or other invasive infections, conjunctivitis, otitis, sinusitis, pneumonia or bronchitis. Minimal inhibiting concentrations were determined by a microdilution technique in Mueller Hinton broth supplemented with 10 microliters/ml NAD and 2-5% lysed horse blood. A concentration of 1 x 10(5) to 5 x 10(5) CFU/ml was used as the inoculum. The antibiotics were tested at concentrations ranging from 0.03 to 64 microliters/ml with the exception of trimethoprim-sulfamethoxazole, for which the range of concentrations examined were 0.01/0.25 to 32/512 microliters/ml. All the strains tested were susceptible to ampicillin-sulbactam, cefuroxime and cefotaxime, and more than 95% were susceptible to ampicillin, cefaclor and chloramphenicol. Only 4% were susceptible to erythromycin but most minimal inhibiting concentrations fell into the intermediate category. Strains isolated from adults were more susceptible to trimethoprim-sulfamethoxazole than strains isolated from children (85% vs 66%; p = 0.011).

Adult↗

PubMed1993

[Renal angiomyolipoma and oncocytoma: sensitivity, diagnosis, and controversy regarding CT and MR].

We have studied the accuracy of CT and MR in 9 oncocytoma and 6 angiomyolipoma, observed in our department from 1985 to 1991. The radiographic patterns of angiomyolipoma are due to the presence of fat in the tumors: on the CT angiomyolipoma appeared as low-density lesions (negative Hounsfield units) with an area of intermixed tissue density which represented myomatous and angiomyomatous elements. The infusion of contrast medium increased the difference between neoplasm and parenchyma because of the scarce enhancement of the angiomyolipoma. MR imaging of angiomyolipoma exhibited areas of high intensity signals on both T1 and T2 weighted images. The infusion of Gadolinium (1 mmol/kg) decreased the difference of signal intensity between angiomyolipoma and parenchyma so that the lesions appeared less clear. As far as oncocytoma diagnosis is concerned, neither CT nor MR appeared less clear. As far as oncocytoma diagnosis is concerned, neither CT nor MR appeared accurate and no specific pattern was identified. The "central stellate scar" was shown on CT in only 1 oncocytoma 7 cm large.

Adenoma, Oxyphilic↗

PubMed1993

[Echo-guided transperineal and transrectal prostatic biopsy: complications of the 2 methods].

We evaluated the complications of transrectal and transperineal ultrasound-guided prostatic biopsy in 280 patients. All patients underwent antibiotic prophylaxis with a different scheme according to the approach for the biopsy. Urine culture and, in some patients, blood culture have been collected after biopsy. We have reported the same rate of complications for the two modalities except for a lower rate of positive urine culture and blood culture in the group of patients submitted to transperineal biopsy; this type of approach, then, should be considered of first choice in some patients with a higher risk of infections.

Aged↗

PubMed1993

DXR depresses the alpha-actinin-induced formation of actin bundles.

The filament-to-filament interactions in cardiac alpha-actinin/F-actin mixtures were investigated in the presence of doxorubicin. Stoichiometrical concentrations of the drug in the assembly medium inhibit the growth of alpha-actinin/F-actin three-dimensional structures, as shown by low speed centrifugation, light scattering, A320nm, electron microscopy and low shear viscosity tests. DXR-induced short actin bundle formation could be related to the inhibition of the bundle elongation mechanism, and furthermore, could account for some morphological evidences in DXR-treated living cells. Our results support both the formation pathway of actin bundles as proposed by Stokes and DeRosier (1991), and the observations of Molinari et al. (1990) on the human CG5 cell line.

Actin Cytoskeleton↗

PubMed1992

Childhood cancer registry of the Province of Torino, Italy. Survival, incidence, and mortality over 20 years.

Incident childhood cancers in the Province of Torino, Italy (population aged 0 to 14 years averaging 0.5 million) have been registered since 1967. Four population-based exhaustive surveys have been done to collect cases diagnosed during the periods 1967 to 1969, 1970 to 1975, 1976 to 1981, and 1982 to 1986. For each registered child, vital status on June 30, 1988 was assessed. This article reports incidence, mortality, and survival rates over a 20-year period. A statistically significant trend toward an increased incidence of soft tissue sarcomas was identified. Statistically insignificant trends included an increased incidence of brain tumors (probably reflecting improved diagnostic procedures) and a decreased incidence of thyroid tumors. Incidence rates of leukemias in the first year of life tended to decrease. As expected, survival rates of some childhood cancers dramatically improved throughout the 20-year period; this occurred in leukemias, brain tumors, soft tissue sarcomas, and renal tumors. Survival rates are compared with observations in comparable population-based series.

Adolescent↗

PubMed1992

Evidence for polyamine channels in protoplasts and vacuoles of Arabidopsis thaliana cells.

The presence of ion channels permeable to polyamines in the plasma membrane and tonoplast of Arabidopsis thaliana cultured cells was investigated by means of the patch-clamp technique in the whole-cell configuration. Evidence is shown for channels, activated by depolarizations in protoplasts and by hyperpolarizations in vacuoles, with slow time course of activation, permeable to putrescine, spermidine and spermine.

Cell Membrane↗

PubMed1992

A study of the incidence of urogenital Chlamydia trachomatis in patients attending specialized departments of Rome, Milan and Turin, Italy.

A study of Chlamydia trachomatis was conducted in 5270 subjects seen at clinics of the Faculty of Medicine and Surgery at La Sapienza University in Rome, the S. Anna Hospital in Turin, and the Provincial Maternity Hospital Institute in Milan. In these areas, C. trachomatis was present in 5.8% of the cases examined; in addition it was present with statistically significant frequencies in cases of salpingitis (49.1) and epididymitis (21.7). It may also be found in cases of extrauterine pregnancy, sterility and abortion. Those most affected were women who had begun their sexual activity at an early age, were under 25, had several sexual partners and who used the coil and/or spermicides. A routine check for C. trachomatis should be considered for those women with those risk factors.

Adolescent↗

PubMed1992

Interaction of cardiac alpha-actinin and actin in the presence of doxorubicin.

The therapeutic use of doxorubicin (an antitumoral antibiotic belonging to the anthracycline group) is limited by its cardiotoxicity. Adriamycin (DXR) causes myocardial subcellular damage, such as myocytolysis, disarray of actin filaments, and alterations in the Z-band with loss of sarcomeric organization. We studied the effect of stoichiometrical concentrations of DXR on the interaction between cardiac actin and alpha-actinin in solution. Doxorubicin inhibits the formation of alpha-actinin/actin tridimensional networks and bundles. The main effect of the drug seems to be on the size of the actin polymers.

Actin Cytoskeleton↗