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Biomedical subjects

R Colombo

Publications and source records attributed to R Colombo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Determination of organophosphorus pesticides in honeybees after solid-phase microextraction.

A method based on solid-phase microextraction (SPME) followed by gas chromatography with nitrogen-phosphorus detection was developed for the purpose of determining 18 organophosphorus pesticide residues in honeybee samples (Apis mellifera). The extraction capacities of polyacrylate and poly(dimethylsiloxane) fibers were compared. The main factors affecting the SPME process, such as the absorption time profile, salt, and temperature, were optimized. The method involved honeybee sample homogenization, elution with an acetone:water solution (1:1) and dilution in water prior to fiber extraction. Moreover, the matrix effect on the extraction was evaluated. In samples spiked at the 0.2 mg kg(-1) level, the coefficient variation was between 1 and 13% and the detection limits were below 10 microg kg(-1). The SPME procedure was found to be quicker and more cost-effective than the solvent extraction method commonly used. The method was applied successfully to environmental screening. Parathion methyl was detected and confirmed in the real samples analyzed.

Animals↗
PubMed2001

Recent origin and spread of a common Lithuanian mutation, G197del LDLR, causing familial hypercholesterolemia: positive selection is not always necessary to account for disease incidence among Ashkenazi Jews.

G197del is the most prevalent LDL receptor (LDLR) mutation causing familial hypercholesterolemia (FH) in Ashkenazi Jew (AJ) individuals. The purpose of this study was to determine the origin, age, and population distribution of G197del, as well as to explore environmental and genetic effects on disease expression. Index cases from Israel (n=46), South Africa (n=24), Russia (n=7), The Netherlands (n=1), and the United States (n=1) were enlisted. All trace their ancestry to Lithuania. A highly conserved haplotype (D19S221:104-D19S865:208-D19S413:74) was identified in G197del chromosomes, suggesting the occurrence of a common founder. When two methods were used for analysis of linkage disequilibrium (LD) between flanking polymorphic markers and the disease locus and for the study of the decay of LD over time, the estimated age of the deletion was found to be 20 +/- 7 generations (the 95% confidence interval is 15-26 generations), so that the most recent common ancestor of the mutation-bearing chromosomes would date to the 14th century. This corresponds with the founding of the Jewish community of Lithuania (1338 a.d.), as well as with the great demographic expansion of AJ individuals in eastern Europe, which followed this settlement. The penetrance of mutation-linked severe hypercholesterolemia is high (94% of heterozygotes have a baseline concentration of LDL cholesterol (LDL-C) that is >160 mg/dl), and no significant differences in the mean baseline lipid level of G197del carriers from different countries were found. Polymorphisms of apolipoprotein E and of scavenger-receptor class B type I were observed to have minor effects on the plasma lipid profile. With respect to determinative genetic influences on the biochemical phenotype, there is no evidence that could support the possibility of a selective evolutionary metabolic advantage. Therefore, the founder effect in a rapidly expanding population from a limited number of families remains a simple, parsimonious hypothesis explaining the spread of G197del-LDLR-linked FH in AJ individuals.

Adolescent↗
PubMed2001

Multiresidual method for the gas chromatographic analysis of pesticides in honeybees cleaned by gel permeation chromatography.

The analysis of several organophosphorus and carbamate pesticide residues in the bodies of honeybees using gas chromatography (GC) and gel permeation chromatography (GPC) clean-up is described. Freeze-dried or lyophilized insect samples were blended with diatomaceous earth (Extrelut) then underwent elution with methylene chloride. This extraction method has shown good recovery on various spike standard levels. Samples are cleaned up by GPC with a Bio Beads SX 3 column and a cyclohexane-ethylacetate (1:1) eluant. Organophosphorus and carbamate compounds are quantified using capillary gas chromatography. Good linearity ranges were observed for all compounds. The extraction process was rapid and results were good, despite the complexity of the matrix on which it was applied. It allowed a reduction both in cost and the consumption of solvents, thereby safeguarding the health of the analyst and the environment. Environmental monitoring using bees was confirmed to be a valid procedure.

Animals↗
PubMed2001

Evaluation of intra-muscular EMG signal decomposition algorithms.

We propose and test a tool to evaluate and compare EMG signal decomposition algorithms. A model for the generation of synthetic intra-muscular EMG signals, previously described, has been used to obtain reference decomposition results. In order to evaluate the performance of decomposition algorithms it is necessary to define indexes which give a compact but complete indication about the quality of the decomposition. The indexes given by traditional detection theory are in this paper adapted to the multi-class EMG problem. Moreover, indexes related to model parameters are also introduced. It is possible in this way to compare the sensitivity of an algorithm to different signal features. An example application of the technique is presented by comparing the results obtained from a set of synthetic signals decomposed by expert operators having no information about the signal features using two different algorithms. The technique seems to be appropriate for evaluating decomposition performance and constitutes a useful tool for EMG signal researchers to identify the algorithm most appropriate for their needs.

Action Potentials↗
PubMed2001

The shortening reaction of forearm muscles: the influence of central set.

OBJECTIVE: The EMG of the forearm muscles shortened by an imposed wrist joint displacement has been studied at different levels and distribution of background muscle activity and with different instructions to the subjects, in order to test the hypothesis that the recorded EMG response (shortening reaction, ShoRe) could be deliberate in origin. METHODS: Ten normal subjects were examined. A torque motor induced 50 degrees wrist extension or flexion at 500 degrees /s. The subjects were relaxed or exerted a 10% maximal voluntary contraction. They were instructed either not to intervene, or to oppose the displacement, or else to assist it. Several trials were repeated at different initial angles. RESULTS: We found a short-latency reflex (SR) in the stretched muscle, be it flexor or extensor, and a later inconstant ShoRe in the antagonist. ShoRe latency was compatible with that of a reaction time (RT), and was not influenced by the initial wrist angle. When subjects assisted the movement, the EMG burst in the shortening muscle was in every respect a RT; when they opposed the movement, the ShoRe disappeared. There was a strict temporal relationship between SR duration and ShoRe latency. CONCLUSIONS: We suggest that the brain would deliberately trigger the ShoRe on recognizing the displacement direction. The occurrence of such activity in the shortened muscle makes the SR to abruptly stop. The temporal relationship between the duration of the SR and onset of the ShoRe can be an expression of the inhibition on the SR burst by the cortical drive to the antagonist muscle being shortened, possibly through the action of spinal inhibitory interneurones. The ShoRe would complete the movement momentarily braked by the SR and redistribute the muscle tone across antagonists, appropriate for the new muscle length.

Adult↗
PubMed2001

Effect of local hyperthermia of the bladder on mitomycin C pharmacokinetics during intravesical chemotherapy for the treatment of superficial transitional cell carcinoma.

AIMS: To assess the effect of local hyperthermia on the systemic absorption of mitomycin C (MMC) during intravesical chemotherapy for the treatment of superficial transitional cell carcinoma of the bladder, and to establish the likely safety of this procedure. METHODS: Group 1 (n = 12) received 20 mg intravesical MMC plus local hyperthermia, group 2 (n = 13) 20 mg MMC alone, group 3 (n = 16) 40 mg MMC plus local hyperthermia and group 4 (n = 10) 40 mg MMC alone. Patients in groups 1, 2, and 4 underwent post-tumour resection adjuvant treatment, whereas those in group 3 still had tumour present and were treated to eradicate it. Intravesical instillation lasted 60 min, with the solution (50 ml) being replaced after the first 30 min. Blood samples were taken before, and every 15 min during instillation. MMC concentrations in plasma and in urine were determined by h.p.l.c. RESULTS: The highest MMC plasma concentration (67.9 ng ml(-1)) occurred in a patient in group 3. This value was well below the threshold concentration (400 ng ml-1) for myelosuppression. Local hyperthermia associated with the intravesical chemotherapy enhanced plasma MMC concentrations at 30, 45 and 60 min compared with chemotherapy alone (Group 1 vs 2, P < or = 0.008). Systemic exposure to MMC was not significantly increased by doubling the intravesical dose when intravesical chemotherapy alone was administered. Patients in group 3 displayed the highest degree of MMC absorption and the greatest variability in pharmacokinetics between patients. CONCLUSIONS: Local hyperthermia enhances the systemic absorption of MMC during intravesical chemotherapy for bladder cancer. In the doses used, plasma MMC concentrations were always more than six times lower than those shown to cause toxicity.

Administration, Intravesical↗
PubMed2001

Nerve and seminal sparing radical cystectomy with orthotopic urinary diversion for select patients with superficial bladder cancer: an innovative surgical approach.

PURPOSE: Radical cystectomy is advocated for high risk patients with superficial bladder cancer. To preserve complete urinary continence, normal sexual function and fertility in young patients, we developed an innovative technique based on nerve and seminal sparing radical cystectomy. MATERIALS AND METHODS: Radical cystectomy was recommended for 8 patients with superficial bladder cancer that was not conservatively manageable. Average patient age was 44 years (range 36 to 48), and all patients were extremely anxious to maintain potency and fertility. The surgical procedure consisted of transurethral resection of the prostate, pelvic iliac lymph node dissection and extraperitoneal radical cystectomy performed while preserving the vas deferens seminal vesicles and neurovascular bundles. Urinary diversion was accomplished with a W-shaped ileal reservoir anastomosed to the prostatic capsule. RESULTS: Patients were generally discharged from the hospital 15 days after surgery, and postoperative morbidity was limited. Daytime and nighttime continence was immediate and complete after catheter removal. Normal erectile function was clinically documented in all patients while fertility potential with semen retrieval via urine was recorded in 7. The quality of life, as reported by the patients, was highly satisfactory at 18-month followup. CONCLUSIONS: The surgical approach we describe should be considered in young men with clinical, superficial bladder tumors refractory to conservative treatment who wish to maintain potency and fertility, and to guarantee as good a quality of life as possible. To ensure oncological success scrupulous patient selection is a primary step of this procedure.

Adult↗
PubMed2001

Counselling the patient with prostate cancer about treatment-related erectile dysfunction.

At present, a significant proportion of patients with prostate cancer are diagnosed at an early stage and may receive treatments able to bring about the long-term control of the disease. Thus, the impact of available treatments on the patient's quality of life has been gaining increasing importance; for patients with prostate cancer, counselling on the treatment-related effects on sexual function has become mandatory. Radical prostatectomy is very frequently performed in patients with clinically localized prostate cancer. Postoperative erectile function has been reported as being satisfactory in the majority of the patients operated on in centers of excellence for this procedure. However, overall, the results for postoperative potency are disappointing in view of the large amounts of data available from community practices. Attempts to improve postoperative potency include the intraoperative use of cavernous nerve stimulation and grafting of peripheral nerves to restore the innervation of the corpora cavernosa. Erectile dysfunction has also been associated with prostate radiotherapy. It has been shown that both ultrasound-guided brachytherapy and three-dimensional conformal radiation therapy cause an impairment of erectile function that is usually seen some time after the completion of therapy. Treatment with sildenafil citrate remains a viable option both for patients treated with radical prostatectomy (in whom the cavernous nerve function is at least partially present) and in patients treated with radiotherapy.

Brachytherapy↗
PubMed2001

Thermo-chemotherapy and electromotive drug administration of mitomycin C in superficial bladder cancer eradication. a pilot study on marker lesion.

OBJECTIVE: To assess the feasibility and safety of two novel methods for intravesical chemotherapy administration in patients suffering from superficial bladder carcinomas. To draw preliminary considerations concerning the ablative effect on marker lesion using novel approaches compared to standard intravesical chemotherapy. METHODS: Eighty patients suffering from single, recurrent, low-stage, low-grade superficial bladder tumor entered a prospective nonrandomized study. Thirty-six of them were treated by means of mitomycin C instillation as a standard procedure. In 29 patients mitomycin C solution was administered in combination with local microwave-induced hyperthermia and in 15 patients the mitomycin C solution was administered according to the electromotive drug procedure. The treatment was scheduled as a short term neo-adjuvant regimen prior to transurethral resection. Feasibility and safety of the different procedures were evaluated on an outpatients basis. The local toxicity induced by different approaches was defined and compared using a subjective questionnaire. RESULTS: Both intravesical chemotherapy administered in combination with hyperthermia and according to the electromotive drug technique appeared to be feasible and safe. Local toxicity induced by thermo-chemotherapy was more severe than that registered for electromotive drug technique and standard intravesical chemotherapy. Local toxicity was always short and self healing without early or delayed major complications. A higher complete response rate on marker lesion was observed after thermo-chemotherapy compared to other administration methods. CONCLUSION: The intravesical administration of mitomycin C can be safely performed in the form of both thermo-chemotherapy and electromotive drug approach with an increased ablative success rate on small superficial tumor involving only minimal local side effects.

Antibiotics, Antineoplastic↗
PubMed2001

Effect of intermittent subdiastolic pressure in thigh cuffs on human arterial baroreflex.

BACKGROUND: We investigated the effects of subdiastolic variations of the pressure inside the thigh cuffs on cardiovascular oscillations and arterial baroreflex sensitivity in humans. METHODS: During 10 min of controlled breathing at low (0.1 Hz) and high (0.25 Hz) frequencies, 30 healthy subjects underwent variations of the pressure inside the thigh cuffs (from 0 to 40 mmHg) at 0.25 and 0.1 Hz respectively; the periods of controlled breathing without cuff pressure modulation were used as a control. The frequency responses of cardiovascular signals were assessed using spectral analysis, and baroreflex sensitivity by the sequence method. RESULTS: Cuff pressure modulation at 0.25 Hz did not affect the RR interval, arterial pressure, or baroreflex sensitivity; at 0.1 Hz it did not change the RR interval and arterial pressure, but engaged (0.76 +/- 0.2 of coherence) and increased the low frequency oscillations of the RR interval (from 5.6 +/- 1 to 6.1 +/- 0.9 ln ms2, p < 0.05) and improved baroreflex sensitivity by 25% (from 14.2 +/- 9 to 17.7 +/- 10 ms/mmHg, p < 0.01). CONCLUSIONS: Subdiastolic thigh cuff pressure modulation at 0.1 Hz improved the low frequency oscillations of heart rate and baroreflex sensitivity. This approach represents a new and simple non-pharmacological strategy for acutely improving baroreflex sensitivity in humans.

Adult↗
PubMed2001

Bidialysis: a new technique.

An increase in solute removal, a shorter dialysis session, the patient's well being and the reduction of global costs are the principal aims of the new hemodialysis methods. The simultaneous use of two hemodialyzers in hemodialysis has been experimented by other researchers. Our technique involves the use of two cuprophan hemodialyzers in sequence (double filter system: DFS), each one connected separately to fresh dialysate. Fifteen symptomatic large patients were treated with DFS and the results were compared to conventional hemodialysis (CHD). After the first hemodialyzer, modification of pH and electrolytes occurred in the plasma composition. In the second hemodialyzer, urea depuration occurred without further significant changes in hydroelectrolytic or acid-basic plasma patterns. The Kt/V increased from 1.10 to 1.29 (18%). The authors conclude that in DFS there was an advantage in urea clearance, osmolarity stability and reduction of side effects.

Body Weight↗
PubMed2001

Reconfiguration of the severely fibrotic penis with a penile implant.

PURPOSE: Using evidence based methods we prospectively evaluated the impact of a new surgical procedure on penile deformity caused by severe cavernous fibrosis. MATERIALS AND METHODS: In 10 patients with severe penile curvature, shortening and impaired penile rigidity due to fibrosis of the corpora cavernosa we made multiple relaxing incisions of the tunica albuginea and subsequently placed a 3-piece inflatable penile implant. Patients were evaluated before and after the procedure by the International Index of Erectile Function and several general assessment questions. Preoperatively and postoperatively we measured flaccid and erect penile length. RESULTS: At the 6-month followup all International Index of Erectile Function domains were significantly improved compared with preoperative values. Average penile length was increased 2.3 and 3 cm. while flaccid and erect, respectively, compared with before surgery. Complete penile straightening was achieved in 9 of 10 cases (90%). Surgical reoperation was performed in 1 patient (10%) in whom the implant was removed due to scrotal infection and in another (10%) in whom a further single relaxing incision of the fibrotic plaque was needed to attain complete penile straightening. CONCLUSIONS: Patients with severe penile curvature, shortening and impaired penile rigidity due to penile fibrosis may be offered this surgical alternative, which proved to be effective and safe in our preliminary series.

Fibrosis↗
PubMed2000

Different metabolizing ability of thiol reactants in human and rat blood: biochemical and pharmacological implications.

The effect of oxidants, electrophiles, and NO donors in rat or human erythrocytes was analyzed to investigate the influence of protein sulfhydryl groups on the metabolism of these thiol reactants. Oxidant-evoked alterations in thiolic homeostasis were significantly different in the two models; large amounts of glutathione protein mixed disulfides were produced in rat but not in human erythrocytes by treatment with hydroperoxides or diamide. The disappearance of all forms of glutathione (reduced, disulfide, protein mixed disulfide) was induced by menadione only in human erythrocytes. The treatment of rat red blood cells with electrophiles produced glutathione S-conjugates to a much lower extent than in human red blood cells; GSH was only minimally depleted in rat red blood cells. The NO donor S-nitrosocysteine induced a rapid transnitrosation reaction with hemoglobin in rat erythrocytes producing high levels of S-nitrosohemoglobin; this reaction in human red blood cells was negligible. All drugs were cleared more rapidly in rat than in human erythrocytes. Unlike human Hb, rat hemoglobin contains three families of protein SH groups; one of these located at position beta125 is directly implicated in the metabolism of thiol reactants. This is thought to influence significantly the biochemical, pharmacological, and toxicological effects of some drugs.

Adult↗
PubMed2000

Dating the origin of the V170M mutation causing non-type I cystinuria in Libyan Jews by linkage disequilibrium and physical mapping of the SLC7A9 gene.

Cystinuria is an autosomal recessive disorder of the transepithelial transport of amino acids, clinically manifested by the development of kidney stones. Mutations in the gene encoding rBAT (SLC3A1, on chromosome 2p16.3) are linked to type I cystinuria, while the SLC7A9 locus (19q13.1), expressing b0,+ AT protein, is involved in non-type I cystinuria, which is very common among Libyan Jews. Applying two methods for linkage disequilibrium analysis to haplotype data spanning six 19q12-q13.1 polymorphic markers, and relying on the physical distances between the markers and the recently mapped SLC7A9 (CSNU3) locus, the age of the founder missense V170M mutation causing non-type I cystinuria in Jews of Libyan ancestry is calculated to be approximately 14 to 15 generations (g) (95% confidence interval: 9-20 g) or slightly more. The estimated age dates the most recent common ancestor of the mutation-bearing chromosomes back to the time (or some decades before) Jewish families settled in Libya following their expulsion from the Iberian Peninsula. This finding makes the molecular population genetics of cystinuria understandable in the context of the Libyan Jews' history.

Amino Acid Substitution↗
PubMed2000

Age of the intronic GAA triplet repeat expansion mutation in Friedreich ataxia.

Friedreich ataxia (FRDA), the most frequently inherited ataxia, is due in the vast majority of cases to a large expansion of an intronic GAA repeat. Using linkage disequilibrium analysis based on haplotype data of seven polymorphic markers close to the frataxin gene, the age of FRDA founding mutational event(s) is estimated to be at least 682+/-203 generations (95% confidence interval: 564-801 g), a dating which is consistent with little or no negative selection and provides further evidence for an ancient spread of a pre-mutation (at-risk alleles) in western Europe.

Europe↗
PubMed2000

Age and origin of the FCMD 3'-untranslated-region retrotransposal insertion mutation causing Fukuyama-type congenital muscular dystrophy in the Japanese population.

Fukuyama-type congenital muscular dystrophy (FCMD), an autosomal recessive disorder with a high prevalence in the Japanese population, is characterised by severe muscular dystrophy associated with brain malformation (cortical dysgenesis) and mental retardation. In Japan, 87% of FCMD-bearing chromosomes carry a 3-kb retrotransposal insertion of tandemly repeated sequences within the disease gene recently identified on chromosome 9q31, and most of them share a common founder haplotype. FCMD is the first human disease known to be caused primarily by an ancient retrotransposal integration. By applying two methods for the study of linkage disequilibrium between flanking polymorphic markers and the disease locus, and of its decay over time, the age of the insertion mutation causing FCMD in Japanese patients is calculated to be approximately 102 generations (95% confidence interval: 86-117 g), or slightly less. The estimated age dates the most recent common ancestor of the mutation-bearing chromosomes back to the time (or a few centuries before) the Yayoi people started migrating to Japan from the Korean peninsula. This finding makes the molecular population genetics of FCMD understandable in the context of Japan's history and the founder effect consistent with the prevalent theory on the origins of the modern Japanese population.

Asian People↗