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M Coco

Publications and source records attributed to M Coco.

11 recordsLinked to original sources
PubMed2000

2D and 3D dose distribution determination in proton beam radiotherapy with GafChromic film detectors.

This paper presents the results obtained using radiochromic (MD-55 GafChromic) film for the 2D and 3D dosimetric reconstruction of the dose delivered by a proton beam under the real conditions of a programme of radiotherapy treatment for ocular tumours. Standard microdensitometric measurements were used to determine the variation in film optical density (O.D.) vs dose. Calibration curves were obtained by least-square fitting of the experimental OD values using a second order polynomial. This allows conversion of O.D. to dose. With this procedure it was possible to determine the distribution of the dose delivered by the proton beam in a phantom composed of layers of GafChromic film, with high surface spatial resolution and, through sections, the complete mapping of the dose delivered to a volume subjected to irradiation, as in a course of radiotherapy treatment.

Eye Neoplasms↗
PubMed2000

Increased incidence of hip fractures in dialysis patients with low serum parathyroid hormone.

To study the complications of renal osteodystrophy in patients with end-stage renal disease, we reviewed the incidence of hip fractures in our outpatient dialysis population from 1988 to 1998. One thousand two hundred seventy-two patients were treated for a total of 4,039 patient-years; 56 hip fractures were documented during this period. The incidence of hip fractures was many times greater in the dialysis patients than in the general population in each of the age-, race-, and sex-matched subgroups. The 1-year mortality rate from the hip fracture event was nearly two and a half times greater in the dialysis patients compared with the general population. The incidence of hip fractures in the first half of the decade was similar to that observed in the second half. When parathyroid hormone (PTH) levels were evaluated, we determined that patients with lower serum PTH levels were more likely to sustain a hip fracture than patients with higher PTH levels (P: < 0.006). In addition, we determined that patients with lower PTH levels had an earlier mortality than patients with higher PTH levels (P: < 0.03). We conclude that despite more aggressive therapy directed toward bone health in our dialysis patients in recent years, the incidence of hip fractures and their devastating morbidity and mortality remained unchanged over the past decade. Lower PTH levels may predispose to earlier mortality.

Adolescent↗
PubMed2000

Women's health issues in a dialysis population.

BACKGROUND: As women receiving hemodialysis are evaluated frequently by the nephrologist, we hypothesized that women's health issues are better addressed in the dialysis patient than in the general population. PATIENTS AND METHODS: We surveyed the female patients in our dialysis population. 97% of the women approached agreed to participate. We found that 55.4% of our cohort had received routine gynecologic care. 50% of the women had undergone a Papanicolaou (Pap) smear in the last year. Of the women aged 40-50, 55% had undergone a mammogram in the last 2 years. In women over age 50, 71% received an annual mammogram. RESULTS: We found that 57% of the women were amenorrheic before starting renal replacement therapy while 16% had become amenorrheic after dialysis was started. 27% were still menstruating at the time of the survey. Only 4% of the amenorrheic women interviewed were currently on hormone replacement therapy (HRT) as compared with 20% of women in our general medical clinics. While 67% stated that they would take hormone replacement if offered, 89% had never been offered HRT. Variables that positively correlated with willingness to take HRT were a history of a hysterectomy and more skilled work history. Although nephrologists surveyed at our academic facility agreed that amenorrheic women with renal disease benefited from HRT, many believed that it is not the role of the nephrologist to prescribe it. CONCLUSION: Despite frequent contacts with medical providers, women's health issues for patients on dialysis may not receive the same attention as women in the general population

Adult↗
PubMed1997

An evaluation of the effectiveness of oral iron therapy in hemodialysis patients receiving recombinant human erythropoietin.

Iron balance is critical for adequate erythropoiesis in hemodialysis patients treated with recombinant human erythropoietin (EPO). The role of oral iron therapy in maintaining or replenishing iron stores has not yet been well defined in such patients. We undertook a double-blind, placebo-controlled study to evaluate the efficacy of oral iron in 49 hemodialysis patients, divided into two groups, based on adequate or deficient iron stores. These groups were treated for 3 months with 150 mg elemental iron (Polysaccharide complex, Central Pharmaceuticals) or placebo, twice daily. Laboratory parameters were followed for five months. These parameters included: hematocrit (Hct), ferritin, transferrin saturation (Tsat), and zinc protoporphyrin (ZPP). A side-effects questionnaire was recorded monthly. Our results indicate that iron replete patients show evidence of falling iron stores during the study period; this observation was identical in both oral iron and placebo subgroups. Iron deficient patients had a significantly greater drop-out rate due to side effects when compared to iron replete patients (33% vs. 8%), despite equivalent responses to the side-effect questionnaire. We conclude: 1) Oral iron fails to maintain iron stores in iron replete patients; 2) Iron deficiency observed in this study may be due to poor medication compliance rather than side-effects.

Administration, Oral↗
PubMed1996

Physical activity influences heart rate variability and very-low-frequency components in Holter electrocardiograms.

OBJECTIVE: A major proportion of RR interval variability in long-term recordings is due to slow (< 0.03 Hz) fluctuations, which seem to be a good predictor of survival after myocardial infarction, whose origin remains unclear. METHODS: To study the effect of physical activity we compared by spectral analysis of the RR interval in 10 healthy human subjects (aged 28[s.e. 2] years) during 1-h periods each of rest (no activity), alternating rest and mild exercise (rhythmic activity), and normal spontaneous (random) activity. RESULTS: Compared to rest, during both random and rhythmic activities, the RR variance increased significantly (from 5802[1030] to 13388[1448] ms2, P < 0.05, and to 24959[2901], P < 0.001) due to an increase in power below 0.03 Hz (from 3017[467] to 9606[966] ms2, P < 0.01, and to 21 103[2298] ms2, P < 0.001) which explained 55.4, 73.2 and 86.1% of total RR variance, respectively. CONCLUSIONS: The amount of RR variability and its slower fluctuations largely depend on physical activity, regardless of its regular or irregular occurrence. Attempts to predict cardiovascular prognosis on the basis of RR fluctuations should therefore take account of the confounding effect of physical activity since healthier subjects would probably be more active.

Adult↗
PubMed1995

Autonomic and ventilatory components of heart rate and blood pressure variability in freely behaving rats.

The relative role of parasympathetic, sympathetic, and ventilatory influences in the genesis of blood pressure and R-R interval variability is controversial. In 13 freely behaving WKY rats instrumented with venous and arterial catheters and chest electrodes, mean arterial pressure (MAP, mmHg), R-R interval (ms), and respiratory fluctuations were monitored for 90 min in the control condition and after intravenous atropine (0.75 mg/kg) and/or propranolol (1 mg/kg). Spectral power (pw) in the 0.25- to 0.75-Hz (midfrequency, MF) and the 0.75- to 3.0-Hz (high-frequency, HF, respiratory-synchronous) bands was computed in sequences of 400 heartbeats by use of a combined autoregressive analysis. Atropine reduced but did not abolish HF R-R interval pw (from 1.73 +/- 0.50 to 0.39 +/- 0.27 ms2, P < 0.01) and halved HF MAP pw (from 0.41 +/- 0.30 to 0.21 +/- 0.12 mmHg2, P < 0.05), whereas propranolol did not affect HF pw of the R-R interval or MAP. Propranolol also failed to significantly modify MF R-R interval pw (from 0.48 +/- 0.44 to 0.40 +/- 0.34 ms2, P = NS) or MF MAP pw (from 0.54 +/- 0.39 to 0.42 +/- 0.20 mmHg2, P = NS), whereas atropine virtually abolished MF R-R interval pw (from 0.48 +/- 0.44 to 0.01 +/- 0.01 ms2, P < 0.01) and also significantly reduced MF MAP pw (from 0.54 +/- 0.39 to 0.33 +/- 0.24 mmHg2, P < 0.01). The effects of combined blockade were similar to those of atropine alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Vasovagal syncope].

The nature of most syncopal episodes, previously unknown, was recently elucidated by new diagnostic techniques such as the use of the tilt test. The vasovagal syncope can be clinically diagnosed by means of the tilt test. The transitory loss of consciousness during prolonged orthostasis is typically associated with sudden hypotension and bradycardia, which are commonly preceded by relative tachycardia and by premonitory symptoms such as pallor, nausea, asthenia, yawns, hyperventilation, mydriasis, humming, lasting several minutes. The nature of the vasovagal reflex is now better understood: in subjects with vasovagal syncope, during prolonged orthostasis, it was observed a fall in the venous return, inducing an increased sympathetic drive to the heart (with positive inotropic and chronotropic effect) and a lower ventricular filling. The powerful contraction around an almost empty cardiac chamber induces the activation of ventricular mechanoreceptors, and through a reflex mechanism, a sudden increase in the vagal and a sudden reduction in the sympathetic drive. These autonomic changes are responsible for a sudden hypotension and bradycardia. The discussion is still open about the origin of the reduced venous return: it probably originates from a redistribution in the blood volume, due to a venous pooling in the lower limbs or from a reduced muscle tone, because many subjects with vasovagal syncope are slender and with less developed muscle apparatus. Others suggest that a reduction in the sympathetic drive to the vessels, responsible for a progressive hypotension in the minutes preceding syncopal episodes, is the origin of the reduced venous return. In this review a diagnostic pattern for the assessment of the vasovagal syncope is suggested. The medical history, clinical examination, electro- and echocardiogram, chest x-ray identify two main groups of patients (with or without cardiopathy) who will follow different diagnostic protocols. The therapy of vasovagal syncope, which is based on beta-blockers, scopolamine, dysopiramide and plasma expanders, is reviewed.

Hemodynamics↗
PubMed1989

Galactose feeding causes glomerular hyperperfusion: prevention by aldose reductase inhibition.

Experimental dietary galactosemia is known to result in accumulation of the polyol, galactitol, via the aldose reductase metabolic pathway in a variety of tissues, including renal glomeruli. Because increased polyol accumulation also occurs in insulin-dependent diabetes mellitus (IDDM), in which marked renal glomerular hyperperfusion occurs, we have studied glomerular hemodynamics in rats with experimental galactosemia. Insulin deficiency and its accompanying metabolic disorders are not present in this experimental model. In additional groups of animals, aldose reductase inhibitors, either sorbinil or tolrestat, were added to the galactose diet. In all, five groups of rats were studied: regular diet, 50% galactose diet, regular diet plus sorbinil, 50% galactose diet plus sorbinil, and 50% galactose plus tolrestat. The diets were comparable in protein and salt, and the rats were pair fed. Micropuncture and whole kidney clearance measurements were carried out after 10-14 days on these diets. Compared with rats fed the regular diet, those fed with 50% galactose diet had significantly higher glomerular filtration rates, renal plasma flow, single-nephron glomerular filtration rates, and plasma flow (QA), whereas afferent vascular resistance (RA) was decreased. Addition of sorbinil or tolrestat to the high-galactose diet not only prevented renal hyperperfusion but RA and single-nephron filtration fraction (SNFF) were higher than in normal rats, and QA was lower. In addition, sorbinil administration to rats on the control diet caused significant decreases in single-nephron blood flow and the ultrafiltration coefficient and a rise in SNFF.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1975

Indium-113m-labeled polyfunctional phosphonates as bone-imaging agents.

Indium-113m complexed with polyfunctional phosphonates EDTMP (an analog of EDTA with carboxylic groups replaced by phosphate groups) and DTPMP (an analog of DTPA) showed preferential skeletal localization in experimental animals. Excellent images of the rabbit skeleton were obtained with both 113mIn and 111In complexes using the scintillation camera. In tissue radioassay using 85Sr as a simultaneous biologic standard, 113mIn-EDTMP compound showed higher concentration in the skeleton than the DTPMP complex and its bone uptake was comparable to that of 85Sr. Renal excretion was greater for the DTPMP complex (70% vs. 50% for EDTMP at 4 hr) and its blood clearance was faster than EDTMP. EDTMP was found to be the superior agent also to two other polyfunctional phosphonates, NTMP and HMDTMP. Because of the excellent skeletal localization with minimal soft-tissue levels, 113mIn-EDTMP may find use in bone scanning in humans wherever 99mTc bone-imaging agents are not available. These compounds may prove useful also in demonstrating acute myocardial infarcts, particularly for repeat studies after 99mTc bone agents have already been administered.

Animals↗
PubMed1975

Technetium-99m-labeled stannous imidodiphosphate, a new radiodiagnostic agent for bone scanning: comparison with other 99mTc complexes.

Imidodiphosphate (IDP) is an analog of pyrophosphate and diphosphonate, with a P-N-P bond instead of P-O-P or P-C-P. We have labeled IDP with 99mTc quantitatively (98%) using stannous ions as the reducing/complexing agent in a freeze-dried kit form. Radiobioassay of this compound was carried out in rabbits and the results were compared with those of eight other Tc-labeled bone-imaging agents, using the performance of simultaneously administered 85Sr as a reference standard. The 99mTc-IDP concentrated 20% higher in the bone, and its soft-tissue and blood levels were lower than with 85Sr. By comparison, the concentrations in the bone of the other 99mTc agents were 20% less than that of 85Sr. Regarding blood levels, Tc-IDP performed worse than the Tc-diphosphonate but better than the pyrophosphate and the other technetium complexes. Scintillation camera images of 99mTc-IDP in both rabbits and dogs showed excellent details of the skeleton. In a preliminary human study, images with 99mTc-IDP were somewhat inferior to those comparably procured with 99Tc-methylene diphosphonate, but count rates with the IDP complex were about twice those with the MDP compound. Because of its better bone uptake, however, it is suggested that 99mTc-IDP may be clinically useful in spite of its relatively slow blood clearance.

Adult↗