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Biomedical subjects

R Colombo

Publications and source records attributed to R Colombo.

At least 91 records · Page 5Linked to original sources
PubMed1996

Neoadjuvant combined microwave induced local hyperthermia and topical chemotherapy versus chemotherapy alone for superficial bladder cancer.

PURPOSE: We evaluated the effectiveness of local bladder hyperthermia and intravesical chemotherapy compared to intravesical chemotherapy alone in the treatment of superficial transitional cell carcinoma. MATERIALS AND METHODS: A new system designed to deliver simultaneously local bladder hyperthermia and intravesical chemotherapy has been developed at our institute. The system consists of a computerized 915 MHz. microwave source that directly heats the bladder walls (within a temperature range of 42.5 to 45.5C) using a transurethral catheter. From February 1989 to December 1993, 52 patients 44 to 81 years old (mean age 64.3) with superficial stages Ta to T1, grades 1 to 3 transitional cell carcinoma of the bladder were selected for neoadjuvant intracavitary treatment. Tumors were left intact as marker lesions. Of the patients 29 were randomly assigned to receive combined neoadjuvant intravesical chemotherapy and local hyperthermia (group 1), while 23 received intravesical chemotherapy alone (group 2). The treatment protocol included multiple sessions performed on an outpatient basis. Mitomycin C (40 mg. in 50 cc distilled water) was used for intravesical chemotherapy in both groups. All patients underwent transurethral resection of residual tumors and of all suspicious areas 7 to 10 days after completion of treatment. Only a complete response was considered for statistical analysis. RESULTS: A pathological complete response was documented in 19 cases (66%) in group 1 and 5 (22%) in group 2 (chi-square p< 0.01). CONCLUSIONS: According to these preliminary data, microwave induced hyperthermia combined with local intravesical chemotherapy seems to be a feasible, safe and promising approach for neoadjuvant and minimally invasive treatment of superficial bladder cancer.

Adult↗
PubMed1995

Decreased heart rate variability in amyotrophic lateral sclerosis.

Autoregressive spectral analysis of heart rate variability (HRV) was performed in 29 patients with amyotrophic lateral sclerosis (ALS) and 33 age-matched healthy subjects to evaluate the involvement of the autonomic nervous system. HRV analysis provides a means to recognize low (LF) and high (HF) frequency components, respectively mediated by sympathetic and parasympathetic heart control. An increase in the mean heart rate at rest (P < 0.001), a decrease in standard deviation of R-R interval as well as in PNN50 (P < 0.001), and an increase in the LF/HF component ratio (P < 0.01) were found in the ALS patients, indicating a vagal-sympathetic imbalance. These alterations were not related to the clinical features and to the duration of the disease. Our results suggest a subclinical involvement of the autonomic nervous system in ALS, particularly affecting parasympathetic cardiovascular control.

Adult↗
PubMed1995

H2O2-treated actin: assembly and polymer interactions with cross-linking proteins.

During inflammation, hydrogen peroxide, produced by polymorphonuclear leukocytes, provokes cell death mainly by disarranging filamentous (polymerized) actin (F-actin). To show the molecular mechanism(s) by which hydrogen peroxide could alter actin dynamics, we analyzed the ability of H2O2-treated actin samples to polymerize as well as the suitability of actin polymers (from oxidized monomers) to interact with cross-linking proteins. H2O2-treated monomeric (globular) actin (G-actin) shows an altered time course of polymerization. The increase in the lag phase and the lowering in both the polymerization rate and the polymerization extent have been evidenced. Furthermore, steady-state actin polymers, from oxidized monomers, are more fragmented than control polymers. This seems to be ascribable to the enhanced fragility of oxidized filaments rather than to the increase in the nucleation activity, which markedly falls. These facts; along with the unsuitability of actin polymers from oxidized monomers to interact with both filamin and alpha-actinin, suggest that hydrogen peroxide influences actin dynamics mainly by changing the F-actin structure. H2O2, via the oxidation of actin thiols (in particular, the sulfhydryl group of Cys-374), likely alters the actin C-terminus, influencing both subunit/subunit interactions and the spatial structure of the binding sites for cross-linking proteins in F-actin. We suggest that most of the effects of hydrogen peroxide on actin could be explained in the light of the "structural connectivity," demonstrated previously in actin.

Actinin↗
PubMed1995

An original balloon-expanding urethral suture guide for radical prostatectomy.

Between August 1991 and July 1994, an original balloon-expanding urethral suture guide (24 F) was used in 157 consecutive cases of radical retropubic prostatectomy. Both the instrument and its clinical use are described. This guide guarantees good intraoperative exposure of the sectioned urethral stump during vesical reanastomosis, thus improving the technical feasibility of radical prostatectomy.

Equipment Design↗
PubMed1995

Lactate versus bicarbonate on-line hemofiltration: a comparative study.

In this study, 6 chronic anuric uremic patients underwent lactate hemofiltration (HF) with a substitution fluid, prepared in bags, for 3 months and bicarbonate HF, with continuous on-line preparation of the substitution fluid, for 3 months. We determined Na+, Cl-, K+, total calcium (Ca), ionized calcium (Ca2+), phosphate, intact parathormone (I-PTH), pH, PCO2, PO2, and HCO3- in plasma before, during, and after the treatment, as well as Ca, Ca2+, phosphate, and I-PTH in the ultrafiltrate. Moreover, heart rate (HR) and mean arterial pressure (MAP) were continually recorded during the procedure. Furthermore, the patients underwent echocardiographic study before and after the session. In comparison with lactate, bicarbonate HF caused a significant increase in HCO3- and a decrease in K+ plasma concentrations. This was detectable, with lower significance, even 44 h after the end of the treatment. At the end of the long interdialytic period (68 h after the end of the treatment), no significant difference was detectable. pH and PCO2 showed a significant but transient increase during HF. The other parameters investigated did not differ significantly between the two methods.

Adult↗
PubMed1995

Imaging of renal cell carcinoma with gadolinium-enhanced magnetic resonance: radiological and pathological study.

The use of gadolinium-DTPA enhanced MR imaging (Gd-MR) in detecting and staging of large and small renal neoplasm was investigated in 61 patients with 66 renal cell carcinoma confirmed at surgery. The purpose of the study was also to evaluate the signal intensity of the lesions and to correlate the contrast-enhanced pattern to the pathological components and architecture of the surgical specimens. Forty-four tumors were larger than 3 cm and 22 lesions were smaller than 3 cm. Unenhanced MRI detected all large lesions (44/44) and 63% (14/22) of small lesions, while Gd-MRI detected all large and small neoplasms (100%). The overall staging accuracy was 79 and 87% for plain MRI and Gd-MRI, respectively, but both modalities led to an overstaging of the disease. Enhanced MRI was an excellent staging modality for the evaluation of tumor vascular extension and tumor spread to adjacent structures. The most frequent Gd-MRI pattern of small RCC was hyperintensity, while large lesions were mostly hypointense. The presence of fibrohyaline components seemed responsible for the hyperintense pattern. No specific contrast-enhanced MRI pattern was observed according to the tumor architecture (alveolar, tubular or papillar) of noncystic lesions. On the contrary, cystic lesion appeared as an area of low signal intensity and the use of contrast media improved detection and characterization. The inhomogeneous signal intensity increased the detectability of the lesion.

Adult↗
PubMed1995

[Transurethral needle ablation (TUNA) of the prostate: preliminary results].

A multicentric prospective study was designed in Italy to verify the efficacy and the safety of TUNA-BPH patients treatment. The study is co-ordinate by Progress in Urology Association was started in January 1994. Thirty five patients were treated (Mean age 68.4 +/- 4.1 aa). All patients were selected and evaluated to respect the recommendations of the International Consensus Committee (Paris 1993). The procedure was performed with lidocaine 2.5% urethral gel, oral intake of 10 mg of diazepam and steroidal antiphlogistic drugs 1 hour before treatment. Maximal number of prostatic lesions were 6; in 2 BPH initial cases were done 2 lesions alone. The treatment was interrupted at the third lesion in 2 patients because uncomfortable. Hematuria was observed in all patients, but it was resolved within 12 hours. Irritative symptoms were referred by 10 patients (28.6%) and they spontaneously were insignificant within 24 hours. One patient had an acute prostatitis. In 15 patients (42.6%) was necessary to put a suprapubic cystostomy, but all except one voided within 36 hours. We noted narrow connection between prostatic lesions number and urinary acute retention after TUNA. The average follow-up is 3.2 months (range 0.5-6). At the follow-up urine culture was always negative and PSA values increased in the first month. The value of PSA was always higher than pre-treatment, but from 1 month to 3 months progressively reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
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↗