Trafficking and homing of systemically administered stem cells: the need for appropriate analysis tools of radionuclide images.

AIM: Despite its enormous relevance, homing of hematopoietic stem cells (SCs) remains relatively uncertain due to the limitations of measuring small number of systemically administered cells in the different organs. Despite its high sensitivity, radionuclide detection has been relatively underutilized to this purpose since it cannot differentiate hematopietic SCs recruited by target tissues from those circulating in the blood pool. Our study aims to verify the potential of tracer kinetic approaches in estimating the recruitment of labeled SCs after their systemic administration. METHODS: Twenty-four Lewis rats underwent administration of 2 millions cells labeled with 37 MBq of 99mTc-exametazime. Animals were divided into 2 groups according to administered cells: hematopoietic SCs or cells obtained from a line of rat hepatoma. Cell injection was performed during a planar dynamic acquisition. Regions of interest were positioned to plot time activity curves on heart, lungs, liver and spleen. Blood cell clearance was evaluated according to common stochastic analysis approach. Either fraction of dose in each organ at the end of the experiment or computing the slope of regression line provided by Patlak or Logan graphical approach estimated cell recruitment. At the end of the study, animals were sacrificed and the number of cells retained in the same organs was estimated by in vitro counting. RESULTS: Cell number, documented by the dose fraction retained in each organ at imaging was consistently higher with respect to the "gold standard" in vitro counting in all experiments. An inverse correlation was observed between degree of overestimation and blood clearance of labeled cells (r=-0.56, P<0.05). Logan plot analysis consistently provided identifiable lines, whose slope values closely agreed with the "in vitro" estimation of hepatic and splenic cell recruitment. CONCLUSION: The simple evaluation of organ radioactivity concentration does not provide reliable estimates of local recruitment of systemically administered cells. Yet, the combined analysis of temporal trends of tracer (cell) tissue accumulation and blood clearance can provide quantitative estimations of cell homing in the different organs.

Diagnóstico de infertilidad masculina: necesidad de valoraciones funcionales y cromatínicas / Diagnosis of Male Infertility: A Need of Functional and Chromatin Evaluation

Objetivos: Estudiar la incidencia de alteraciones funcionales y cromatínicas en espermatozoides de pacientes, agrupados según normalidad de los parámetros seminales estándar en función de la quinta edición del manual de la Organización Mundial de la Salud (OMS). Identificar y correlacionar las características alteradas con mayor frecuencia en la subpoblación normal para los parámetros estándar. Materiales y métodos: Estudio prospectivo en el que se evaluaron en muestras de semen de 110 pacientes y 6 donantes fértiles (control), los parámetros seminales estándar (volumen, concentración, motilidad, morfología, células redondas, células peroxidasa-positivas) según las directrices de la OMS, así como test complementarios funcionales (sobrevida 24 horas, test hipo-osmótico, test de estrés modificado) y adicionales (azul de anilina, nitroblue-tetrazolium, TUNEL). Según el resultado de los análisis estándar los pacientes se dividieron en dos grupos (A: todos los parámetros estándar normales; B: al menos uno de los parámetros estándar alterado). Resultados: El 96,61% de las muestras presentó alterada al menos una de las variables analizadas. Los grupos A y B mostraron diferencia estadísticamente significativa en todos los test complementarios. En el grupo A el 93,68% de las muestras presentó al menos un test complementario alterado, y la variable afectada con mayor frecuencia fue la fragmentación del ADN espermático (16,95%). Conclusiones: La profundización en el estudio seminal, introduciendo en la rutina ensayos funcionales y cromatínicos, redunda en un diagnóstico más afinado de la infertilidad del varón. Los parámetros de la OMS deben considerarse como un abordaje primario (AU)

Objectives: To evaluate the incidence of functional and chromatin alterations on spermatozoids in patients grouped according to normality of standard semen parameters based on the 5th edition of the World Health Organization (WHO) guidelines. To identify and correlate the most frequently altered characteristics in the normal standard semen parameters sub-population. Materials and Methods: A prospective study was performed. It evaluated standard semen parameters (volume, sperm concentration, motility and morphology, round cells, peroxidase-positive cells) according to WHO guidelines, as well as functional tests (24hours survival, hypoosmotic swelling test, modified stress test), and additional assays (aniline blue, nitroblue-tetrazolium, TUNEL) in 110 semen samples from patients and 6 from fertile donors (control). Based on standard semen parameters values, patients were divided into two groups (A: all standard parameters normal; B: one altered standard parameter at least). Results: At least one of the variables analyzed was altered in 96.61% of the samples. Groups A and B showed statistically significant differences in all the complementary tests. At least one of the complementary tests were altered in 93.68% of the samples in group A, and the most frequently affected variable was sperm DNA fragmentation (16.95%). Conclusions: Performing a more in-depth seminal study within the routine functional and chromatin assays provides a more precise diagnosis of male infertility. The WHO standards should be considered as a primary approach (AU)

[Diagnosis of male infertility: a need of functional and chromatin evaluation]. / Diagnóstico de infertilidad masculina: necesidad de valoraciones funcionales y cromatínicas.

OBJECTIVES: To evaluate the incidence of functional and chromatin alterations on spermatozoids in patients grouped according to normality of standard semen parameters based on the 5th edition of the World Health Organization (WHO) guidelines. To identify and correlate the most frequently altered characteristics in the normal standard semen parameters sub-population. MATERIALS AND METHODS: A prospective study was performed. It evaluated standard semen parameters (volume, sperm concentration, motility and morphology, round cells, peroxidase-positive cells) according to WHO guidelines, as well as functional tests (24 hours survival, hypoosmotic swelling test, modified stress test), and additional assays (aniline blue, nitroblue-tetrazolium, TUNEL) in 110 semen samples from patients and 6 from fertile donors (control). Based on standard semen parameters values, patients were divided into two groups (A: all standard parameters normal; B: one altered standard parameter at least). RESULTS: At least one of the variables analyzed was altered in 96.61% of the samples. Groups A and B showed statistically significant differences in all the complementary tests. At least one of the complementary tests were altered in 93.68% of the samples in group A, and the most frequently affected variable was sperm DNA fragmentation (16.95%). CONCLUSIONS: Performing a more in-depth seminal study within the routine functional and chromatin assays provides a more precise diagnosis of male infertility. The WHO standards should be considered as a primary approach.

Ileocecal reservoir reconstruction after total mesorectal excision: functional results of the long-term follow-up.

BACKGROUND: The aim of this study is to obtain functional results of the long-term follow-up after TME and ileocecal interposition as rectal replacement. METHODS: The study included patients operated on between March 1993 and August 1997 who received an ileocecal interposition as rectal replacement. Follow-up was carried out 3 and 5 years postoperatively. For statistical analysis, the paired t-test, rank test (Wilcoxon), and chi-square or Fisher's exact test were applied; level of significance, P<0.05. RESULTS: Forty-four patients were included in the studies. Of these, five were not available and four patients could not be evaluated (dementia 1, radiation proctitis 1, fistula 1, pouchitis 1). Seventeen patients died during the observation period; 12 died of the disease. Recurrence of the disorder occurred in 2 of 35 patients (5.7%); 26 and 18 patients, 3 and 5 years postoperatively, respectively remained in the study. At 5 years, 78% of the patients were continent; mean stool frequency was 2.5+/-1.6 per day. CONCLUSIONS: Functional results and subjective assessment of ileocecal interposition were constant at 3 and 5 years postoperatively. If construction of a colonic J-pouch is not possible due to lack of colonic length, especially after prior colonic resections, the ileocecal interpositional reservoir may offer an alternative to rectal replacement.

[Intrathoracic goiter--a rare mediastinal tumor]. / Die intrathorakale Struma--ein seltener Mediastinaltumor.

Intrathoracic, totally ectopic goiters are rare, but have to be considered as a diagnostic possibility in all mediastinal masses. The displacement of the thyroid tissue inferiorly in connection with the embryogenesis of the heart and the large vessels explains the aetiology of the disease. Ectopic goiters are often asymtomatic or oligosymptomatic. They may be classified into two groups according to their location in the anterior or posterior mediastinum. The diagnostic procedures include standard X-ray and CT scan imaging, eventually combined with radionuclide scintigraphy. Once the diagnosis of a intrathoracic goiter is obtained the treatment is surgical (unknown dignity, risk of compression or other symptoms). The approach of choice is through a median sternotomy in case of a anterior location and a posterolateral thoracotomy in case of a posterior location. We discuss the diagnostic and therapeutic approach in 2 patients with mediastinal goiters--one located in the anterior and one in the posterior mediastinum.

Prognostic usefulness of dobutamine-induced ST-segment elevation and T-wave normalization after uncomplicated acute myocardial infarction.

We followed 229 consecutive patients exhibiting negative T waves on infarct-related electrocardiographic leads; these patients underwent dobutamine stress echocardiography within 10 days after a first uncomplicated acute myocardial infarction. T-wave normalization, but not ST-segment elevation, recognized patients at higher risk of cardiac events and optimized the prognostic accuracy of both myocardial viability and ischemia, to which it was correlated and became an independent predictor in cases of subdiagnostic stress echocardiography.

Evaluation of effective renal plasma flow with I-127 ortho-iodohippurate and I-123 ortho-iodohippurate in rabbits.

RATIONALE AND OBJECTIVES: Radiolabeled ortho-iodohippurate is commonly employed for evaluating effective renal plasma flow (ERPF) by means of either in vivo scintigraphy and/or plasma clearance curves. A new method has recently been developed for measuring levels of stable iodine (iodine-127) in biologic samples, based on the detection of x-ray fluorescence photons. In this study, the authors assessed the potential of the new system to evaluate ERPF by using an iodinated contrast medium with adequate glomerular filtration and tubular secretion properties. MATERIALS AND METHODS: A commercial system was used to evaluate ERPF after intravenous injection of stable I-127 ortho-iodohippurate. The results were compared with the clearance values of I-123 ortho-iodohippurate, considered the reference standard. Seven rabbits under general anesthesia were given intravenous injections of I-123 ortho-iodohippurate and I-127 ortho-iodohippurate. The corresponding plasma curves were evaluated from 4 to 60 minutes to calculate ERPF as the dose/integral of plasma curve. RESULTS: The initial distribution volumes of I-123 ortho-iodohippurate (149.4 mL/kg +/- 12.1) and I-127 ortho-iodohippurate (148.8 mL/kg +/- 11.8) were virtually superimposable, thus confirming the chemical identity of the two compounds. The plasma clearance values for I-127 ortho-iodohippurate (11.15 mL/min kg(-1) +/- 1.44) were slightly (not significantly) higher than those for I-123 ortho-iodohippurate (10.49 mL/min kg(-1) +/- 1.41), perhaps because of a relative "mass" load effect of the iodinated medium. CONCLUSION: The results obtained in this study demonstrate the feasibility of the new system for evaluating ERPF, provided that a compound with adequate glomerular filtration and tubular secretion properties is employed.

Dobutamine-induced T wave positivization after uncomplicated myocardial infarction: a marker of myocardial viability and higher cardiac risk.

BACKGROUND: There is evidence that after uncomplicated acute myocardial infarction, T wave positivization during stress testing may unveil myocardial viability. We evaluated in a prospective study the clinical value of T wave positivization during dobutamine stress echocardiography in patients with recent, first uncomplicated acute myocardial infarction. METHODS: Two hundred twenty-nine patients, who underwent dobutamine stress echocardiography within 10 days of uncomplicated acute myocardial infarction, were selected for exhibiting negative T waves in the infarct area. A mean follow-up of 2.1 +/- 1 years (up to 6 years) was obtained. RESULTS: T wave positivization appeared during dobutamine test in 76 (33%) patients. The agreement of T wave positivization for myocardial viability was 65% (95% confidence interval 59-71). Compared to myocardial viability during dobutamine stress echocardiography, the combination with T wave positivization was more sensitive (55 vs 24%, 95% confidence interval 46-64 vs 17-33) for predicting cardiac events, albeit less specific. Kaplan-Meier survival curves showed 47 (62%) cardiac events in patients with T wave positivization and 70 (46%) cardiac events in the remaining patients (p < 0.05). Soft (n = 91) prevailed over hard (n = 26) cardiac events. CONCLUSIONS: T wave positivization during dobutamine stress echocardiography after uncomplicated acute myocardial infarction identifies patients at higher cardiac risk, and is more sensitive, albeit less specific, for cardiac events than viability alone. T wave positivization is helpful in the case of inconclusive stress echocardiography. The pathophysiology of T wave positivization and its relative value among other variables warrant further analysis.

[Cecum reservoir]. / Das Coecumreservoir.

UNLABELLED: The choice of the best reconstruction technique following resection of either the stomach or the rectum remains a matter of discussion. While there is no problem in reconnecting intestinal segments, which do not serve as a reservoir, there are many different operation techniques to replace the stomach and rectum, producing significantly different functional results. The ileocecal segment offers an excellent intestinal reservoir combined with an antireflux mechanism, thus presenting an ideal replacement for the stomach. For replacement of the rectal reservoir as well, the ileocecal segment may be used in the first line of treatment. METHOD: The ileocecal segment was used in 20 patients following gastric resection and lymphadenectomy to reconstruct the intestinal passage between the esophagus and the duodenal stump (group A). In some further 44 patients (group B) the ileocecal segment was used to replace the rectum between the descending colon and the dentate line following resection for very low-grade rectal cancer. Mortality and morbidity were investigated in both groups. In group A quality of life, weight loss, dumping and reflux symptoms were evaluated. In group B continence, discrimination, defecation quality, urge and the patient satisfaction were investigated. All data were recorded prospectively. RESULTS: Early and late mortality were not different compared to other reconstruction types. In each group one patient died within 60 days postoperatively due to myocardial infarction. The morbidity following stomach replacement was 20%, following rectal replacement 4.6% during hospitalization and 13.8% during follow-up, respectively. One patient complained about heartburn, but endoscopically no pathology was detected in any patient. Three months postoperatively the patients' weight remained stable or started to increase. Three months following rectal replacement 87% of the patients were continent with further improvement over 2 years. Soiling mainly during the night remained over 2 years in 44%. 88% of the patients were completely satisfied 2 years postoperatively. CONCLUSION: The replacement of either the stomach or the rectum using the ileocecal segment with an adequate surgical technique is safe and produces excellent functional outcome regarding the reconstruction of the intestinal passage as well as the reservoir function of the primary organ. Furthermore, preservation of the duodenal passage after gastrectomy may prevent dysregulation of the endocrine and exocrine pancreatic hormones.

A theoretical four-compartment model to evaluate separate kidney technetium-99m-MAG3 kinetics in humans.

BACKGROUND: Pharmacokinetic modeling based on compartmentalization has provided a valuable tool to assess the clearance patterns of various glomerular and tubular agents. However, no models have been proposed thus far that combine vascular data and imaging data in order to gain a deeper knowledge on renal pathophysiology, and to obtain more diagnostic information of clinical relevance. To this aim, we propose a four-pool model for the evaluation of separate renal function. METHODS: In a group of ten normal volunteers and twenty patients with various renal diseases, we tested the four-pool model based on the identification of the two kidneys as two distinct pools. This approach made it possible to integrate the separate kidney contributions deriving from in vivo imaging data, and allows the researcher to quantitate many parameters specific to each kidney. RESULTS: The parameters TERR, TERL, MRTR, MRTL, vR, vL, k3R-1, K3L-1 permit the normal from abnormal states of renal function to be differentiated, as well as monolateral from bilateral renal disease to be separated within the abnormal function group. CONCLUSIONS: The proposed approach combines the advantages of plasma clearance methods with those derived by gamma-camera imaging, and makes it possible to quantitate the differential renal function. This feature may be clinically relevant in renal transplant donors, where full knowledge of renal pathophysiology could guide the procedure.

Colorectal carcinoma: is lymphadenectomy useful?

In order to define the role of lymph node excision in the treatment of colorectal neoplasms, the literature of the past 20 years and the historic publications on this specific subject were reviewed. Special attention was given to statistical relevance, different types of operations, survival and recurrence rates and an attempt was made to decide on the usefulness of lymphadenectomy and which operation is the best to treat colorectal cancer.

Different clinical and prognostic significance of painful and silent myocardial ischemia detected by exercise electrocardiography and dobutamine stress echocardiography after uncomplicated myocardial infarction.

Prevalence and prognostic significance of painful and silent ischemia detected by exercise electrocardiography (ECG) and dobutamine stress echocardiography (DSE) were evaluated in 407 consecutive patients recovering from acute myocardial infarction. Painful ischemia assessed by both tests was not associated with different clinical characteristics of patients; on the other hand, it identified a higher risk subgroup compared with silent ischemia during exercise ECG but not during DSE.

Time-course of dobutamine-induced wall motion abnormalities in the infarct area following thrombolytic therapy.

Stress-induced asynergies in the infarct area following thrombolytic therapy are considered to reflect incomplete recanalization of the culprit vessel. However, reperfusion is a dynamic process with successive pathophysiological phases, so that the timing of assessment of residual ischemia may have relevant clinical implications. We studied the time-course of dobutamine-induced homozonal asynergies in 61 (group B) survivors of uncomplicated infarction as compared to 54 (group A) control subjects showing normal response to dobutamine stress echocardiography within 10 days of acute myocardial infarction. The 79 (43 of group A and 36 of group B) patients not presenting new cardiac events underwent further dobutamine stress echo within 90 +/- 17 days, which was positive in 20 and negative in 59. Persistence of test positivity was observed in just 17/36 (47%) patients, who showed significantly more extensive dobutamine-induced asynergies as compared to pre-discharge evaluation and less frequent (p < 0.01) evidence of viable myocardium. These results arise question about the decisional impact of stress-induced wall motion abnormalities in the culprit vessel area early after thrombolysis in low-risk patients and emphasize the need to further clarify the time factor role in this setting.

Prognostic value of residual ischaemia assessed by exercise electrocardiography and dobutamine stress echocardiography in low-risk patients following acute myocardial infarction.

BACKGROUND: Risk stratification after uncomplicated myocardial infarction is major clinical problem. In particular, the prognostic value of residual inducible ischaemia is still controversial. We compared the relative prognostic value of exercise ECG and dobutamine stress echocardiography performed in the early post-infarction period. METHODS: Four hundred and six patients (53 female) aged 57 +/- 9 years, undergoing maximal exercise ECG and dobutamine stress echocardiography within 10 days of an uncomplicated myocardial infarction off therapy, were prospectively followed-up for 8.8 months. Age, sex, diabetes, smoking habit, hypertension, dyslipidaemia, infarct location, thrombolysis and resting wall motion score index were taken into account among clinical variables. Prognostic correlations were made vs spontaneous events (cardiac death, non-fatal reinfarction and unstable angina requiring hospitalization) whilst patients undergoing revascularization (by means of percutaneous transluminal coronary angioplasty or coronary artery bypass surgery) at the time of the procedure were censored. RESULTS: One hundred and twenty-seven events occurred during the follow-up: 41 (10%) were spontaneous (five deaths, 12 reinfarctions and 24 unstable angina) and 86 procedural (27 angioplasty and 59 bypass surgery). Spontaneous events were not predicted by any clinical, exercise ECG or dobutamine stress echocardiography variable, but the negative predictive value of both tests was excellent (91% and 90% respectively). With a multivariate Cox analysis, male gender, positive low-workload (< 100 W) exercise ECG (P < 0.0001), positive low-dose dobutamine stress echocardiography (P < 0.0001) and rest-stress wall motion score index variation (P < 0.001) were found to predict cumulative cardiac events with an independent and additive value. Dobutamine stress echocardiography was significantly more sensitive (P < 0.05) and less specific (P < 0.01) in predicting the outcome of patients with anterior infarction, whilst exercise ECG was significantly more sensitive (P < 0.05) in patients with non-Q wave infarction. CONCLUSIONS: (1) Spontaneous events are poorly predicted by provocative tests in low-risk patients after uncomplicated myocardial infarction. (2) However, both exercise ECG and dobutamine stress echocardiography can predict a favourable outcome with a very high negative predictive value. (3) Dobutamine stress echocardiography should be considered a secondary option in cases where the exercise ECG is equivocal or when the location of ischaemia is a relevant issue. (4) The possibility that the two tests have a differential utility depending on the infarct location and type (Q wave vs non-Q wave) may be clinically relevant and deserves further evaluation.

Influence of etiology on the course and outcome of acute pancreatitis.

It has been supposed that there are differences with regard to clinical course and outcome due to the underlying etiological factor in acute pancreatitis. Therefore, the objective of this study was to analyze the severity of the disease, serum enzymes, indicators of necrosis, systemic complications, and mortality in acute pancreatitis with regard to the etiology. One hundred ninety patients with acute pancreatitis (127 male, 63 female) were studied prospectively and subdivided into three etiological groups: (i) alcohol, (ii) gallstones, and (iii) other causes and idiopathic acute pancreatitis. Severity scores (Ranson and Bank) and findings by contrast-enhanced computed tomography were similar in all three groups. Analysis of serum enzymes [lipase, aspartate aminotransferase (ASAT)] and indicators of necrosis (C-reactive protein, alpha 1-antitrypsin, alpha 2-macroglobulin, and lactate dehydrogenase) showed only for ASAT within 24 h significantly higher levels in biliary acute pancreatitis in comparison with the other groups. There were no differences in the rate of infected pancreatic necrosis and mortality in alcohol-related acute pancreatitis (31 and 5.3%), biliary acute pancreatitis (38 and 10%) and acute pancreatitis due to other etiological factors (43 and 5.5%). In conclusion, this study clearly showed that once the pathogenetic mechanisms have initiated the disease, the course and outcome of acute pancreatitis are not influenced by the underlying etiological factor.

Simultaneous estimation of glomerular filtration rate and renal plasma flow.

UNLABELLED: Comparing the measurements of both glomerular filtration (GFR) and tubular excretion rates [TER(MAG3)] by multi-sample and single-sample methods has been performed after a single bolus injection of 3.7 MBq 51Cr-EDTA plus 37 MBq 99mTc-MAG3. METHODS: We studied 17 healthy volunteers and 28 patients with a wide range of renal function. For each plasma clearence curve, nine plasma samples were drawn at intervals from 10 to 240 min after injection of tracers. When comparing individual values for GFR and TER (MAG3) from the tracer dilution spaces (VD) with those derived from the analysis of the entire plasma disappearance curves of two radiopharmaceuticals, a good linear correlation appears (r = 0.96). RESULTS: We found that the nadir-error (Sy,x) for predicted GFR occurs at 180 min (11.0 ml/min/1.73 m2), while the nadir-error for predicted TER (MAG3) is reached at 90 min (26.4 ml/min/1.73 m2). CONCLUSION: In the computation of GFR and TER (MAG3) with a single-sample method, it appears that the mean residence time (t) for each tracer represents the optimum plasma sampling time. Our results suggest that the single injection of 51Cr-EDTA and 99mTc-MAG3 followed by blood sampling twice permits accurate simultaneous estimation of GFR and TER (MAG3) and, after correction of the latter kinetic parameter, effective renal plasma flow.

Prognostic value of ploidy of primary tumour and nodal secondaries in colorectal cancers.

Tumour ploidy is of prognostic value in colorectal cancer, DNA aneuploid tumours having a worse outlook. Nearly all studies have concentrated on the DNA content of the primary tumour. We have examined the ploidy of the primary tumour and its lymph node metastases in 71 cases of Dukes' stage C disease, to see whether this provides greater prognostic information than the primary alone. Analysis was performed using formalin-fixed, paraffin-embedded tumour sections. Ploidy of primary and metastases was different in 20 cases (28%), aneuploid nodes being seen with diploid primaries and vice versa. Ploidy of both the primary (chi 2 = 4.86, P = 0.03) and secondary (chi 2 = 4.86, P = 0.03) tumours predicted survival in univariate analysis. Combining the ploidy of primary and nodes, three prognostic groups could be defined--diploid primaries with diploid metastases (hazard relative to both aneuploid, 0.36) had significantly better survival than cases where the ploidy of the primary and nodes were mixed (relative hazard 0.47-0.56), which did better than cases with aneuploid primary and nodes. This study demonstrates that ploidy variation between primary and secondary tumours is common, and better prognostic information may be gained by studying both.

A theoretical five-pool model to evaluate triiodothyronine distribution and metabolism in healthy subjects.

We have examined the in vivo production, distribution, metabolism, and excretion of radiolabeled triiodothyronine (T3) in eight normal humans using a new five-pool mammillary model which includes four extravascular pools to represent liver, kidney, skeletal muscle, and all other unquantified tissues. Trace amounts of [125I]T3 and [131I]T3 were injected and plasma, stool and urine samples and external counting of liver, kidney, and thigh were drawn following bolus injection of radiolabeled T3. Our results indicate that the skeletal muscle pool represents the largest pool in our system, being 42% of the total-body pool size of the hormone (Qtot = 0.52 +/- 10% [CV] micrograms/kg body weight [BW]). The plasma pool QA (0.090 +/- 9% [CV] micrograms/kg BW) contains approximately 17% of Qtot, while the size of the unquantified tissue pool QE (0.150 +/- 16% [CV] micrograms/kg BW) is approximately 29% of Qtot. Furthermore, the size of liver pool QB and the size of kidney pool QC are about 10% and 2%, respectively, of Qtot. The rate of T3 metabolized in the skeletal muscle pool and in the unquantified composite tissue pool, as a sum, represents approximately 53% of the plasma appearance rate of the hormone (PAR3), while the rate of T3 metabolized in the liver and kidney pools represents 27% and 3% of PAR3, respectively. The rate of T3 excreted via feces and urine, as a sum, accounts for about 20% of PAR3.(ABSTRACT TRUNCATED AT 250 WORDS)

Multicompartmental analysis of triiodothyronine (T3) distribution and metabolism in clinically euthyroid obese individuals.

Triiodothyronine (T3) kinetic studies were performed on ten clinically non-fasting euthyroid obese individuals and on eight normal subjects. Kinetic analysis was carried out according to a three-pool model whose basic approach involved the acquisition of data from both vascular and extravascular sources. The former were represented by the plasma disappearance curves of iv injected radiolabeled T3. The latter included fecal and urinary losses and liver, kidney and thigh uptake. A detailed comparison of the T3 kinetics of obese and normal individuals did not uncover many differences between these two groups in the way the hormone is distributed, metabolized and excreted. The mean value for the plasma equivalent distribution volume of T3(VD3) in obese individuals (27.05 L) was not significantly different from that in controls (24.60 L) nor were significant differences observed between the mean value for the plasma appearance rate of the hormone (PAR3) in obese subjects (29.80 micrograms/day) and that in controls (30.05 micrograms/day). The mean value for the size of the slow pool (Qc), including fatty tissue as well as skeletal muscle, was unchanged in obese individuals when compared with controls, although in the obese subjects the mean value for the mass of fatty tissue was about 5 times greater. In addition, in obese individuals, the mean value for the fractional rate transfer from plasma to the slow pool (Kca), which was 9.06 day-1, did not significantly differ from that in controls (9.22 day-1).(ABSTRACT TRUNCATED AT 250 WORDS)