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Biomedical subjects

B Shapiro

Publications and source records attributed to B Shapiro.

At least 73 records · Page 4Linked to original sources
PubMed1995

A prospective study of bone density and pregnancy after an extended period of lactation with bone loss.

OBJECTIVES: To determine if pregnancy after an extended period of lactation curtails the recovery of maternal bone mineral density. METHODS: Twenty-five women who fully breast-fed their infants for at least 6 months and had a subsequent pregnancy within 18 months of initiating lactation were studied longitudinally. Twenty controls breast-fed similarly, but had no subsequent pregnancy. The women were healthy, well-nourished, and between 20-40 years old. Bone mineral density was measured by dual x-ray energy absorptiometry at the spine and hip. RESULTS: Both cases and controls lost bone mineral density with extended lactation. The case group had a bone mineral density recovery comparable to the controls. CONCLUSION: Women with the dual calcium demands of extended lactation and a subsequent pregnancy are not at risk for failure of bone recovery to pre-lactation levels.

Absorptiometry, Photon↗
PubMed1995

Surgical management of cardiac pheochromocytoma. Resection versus transplantation.

OBJECTIVE: The authors review their experience and that of others who have reported cases in the literature on the surgical management of cardiac pheochromocytomas. SUMMARY BACKGROUND DATA: Cardiac pheochromocytomas are rare cathecolamine-producing tumors that can be densely adherent to myocardium. Because resection can be associated with significant morbidity, we sought to determine the best mode of treatment for these difficult tumors. METHOD: The authors reviewed the experience for management of cardiac pheochromocytomas in their two institutions and those reported in the literature. Follow-up was available for 21 of 26 patients up to 9 years after resection. RESULTS: Twenty-five patients had reconstruction of the native heart; five (20%) died intraoperatively from hemorrhage, one (4%) died postoperatively from sepsis, three (12%) sustained myocardial infarction, one (4%) required a mitral valve replacement, and three (12%) had incomplete resections, two of whom subsequently developed metastatic disease and died. One patient, thought to be a high risk for resection, received an orthotopic heart transplantation. CONCLUSIONS: Surgical resection of cardiac pheochromocytomas can be performed successfully. However, resection of lesions that aggressively invade adjacent myocardium is associated with significant mortality and inadequate control of the neoplasm. Cardiac transplantation should be available as an option before embarking on resection, and it should be performed if mandated by intraoperative findings.

Adult↗
PubMed1995

The cardiovirulent phenotype of coxsackievirus B3 is determined at a single site in the genomic 5' nontranslated region.

We report the construction of chimeric coxsackievirus B3 (CVB3) strains in which sequences of an infectious cDNA copy of a noncardiovirulent CVB3 genome were replaced by the homologous sequences from a cardiovirulent CVB3 genome to identify which of 10 predicted genetic sites determine cardiovirulence. Cardiovirulent phenotype expression was consistently linked to nucleotide 234 (U in cardiovirulent CVB3 and C in avirulent CVB3) in the 5' nontranslated region. Reconstructions of the parental noncardiovirulent CVB3 genome from chimeras restored the noncardiovirulent phenotype when tested in mice. Inoculation of severe combined immunodeficient (scid) mice with the noncardiovirulent CVB3 strain resulted in massive cardiomyocyte necrosis in all animals. Sequence analysis of viral genomes isolated from twelve scid mouse hearts showed that only nucleotide position 234 was different (a C-->U transition) from that in the input parental noncardiovirulent CVB3 genome. Higher-order RNA structures predicted by two different algorithms did not demonstrate an obvious local effect caused by the C-->U change at nucleotide 234. Initial studies of parental and chimeric CVB3 replication in primary cultures of fetal murine heart fibroblasts and in adult murine cardiac myocytes demonstrated that viral RNA transcriptional efficiency is approximately 10-fold lower for noncardiovirulent CVB3 than for cardiovirulent CVB3. CVB3 did not shut off protein synthesis in murine cardiac fibroblasts, nor were levels of viral protein synthesis significantly different as a function of viral phenotype. Taken together, these data support a significant role for determination of the CVB3 cardiovirulence phenotype by nucleotide 234 in the 5' nontranslated region, possibly via a transcriptional mechanism.

Animals↗
PubMed1995

Characterization of adrenal masses with chemical shift and gadolinium-enhanced MR imaging.

PURPOSE: To assess the potential role of chemical shift and dynamic gadolinium-enhanced magnetic resonance (MR) imaging in the characterization of adrenal masses. MATERIALS AND METHODS: Fifty-one adrenal masses (35 adenomas and 16 nonadenomas) in 43 patients were evaluated with chemical shift MR imaging, dynamic gadolinium-enhanced MR imaging, or both. The relative change in the signal intensity (SI) ratio of the adrenal mass to liver and paraspinal muscles was quantitatively and qualitatively assessed. Opposed-phase gradient-echo (GRE) images were compared with in-phase images. RESULTS: With qualitative visual inspection, only adenomas showed a decrease in relative SI ratio on opposed-phase chemical shift images (specificity, 100%; sensitivity, 81%). Quantitative ratios corresponding to 100% specificity were also observed, with similar sensitivities. Adenomas could not be differentiated from nonadenomas with visual assessment of maximum SI after contrast material administration or washout. CONCLUSION: Characterization of an adrenal mass as an adenoma can be made with high specificity and acceptable sensitivity by visually comparing opposed-phase with in-phase GRE images.

Adenoma↗
PubMed1995

Incidentally discovered adrenal masses.

Independently, endocrinology, radiology, and nuclear medicine can not optimally differentiate the etiology of the incidental adrenal mass. Rather, the insight necessary for this task must be contributed by all three disciplines. Incidentally discovered adrenal masses are being detected at an increasing rate. This trend is expected to continue based on the incidence of adrenal masses in autopsy series and the increasing use of high resolution abdominal imaging techniques. CT and MRI are able to definitely characterize only a minority of these lesions (simple cyst, myelolipoma, obvious local malignant invasion). Biochemical screening for hormone excess is essential regardless of a nonsuggestive complete history and physical examination. An argument may be made for not further pursuing nonhypersecreting lesions with the typical features of a benign adenoma on CT scan and an attenuation value of 0 HU or less. Adrenocortical scintigraphy is recommended in all patients with normal biochemical screening tests, especially those with CT attenuation values greater than 0 HU. In this setting, we believe that the functional and anatomical information provided by NP-59 and [75Se]selenomethylnorcholesterol scintigraphy allows one to noninvasively, accurately, and less expensively (Table 9) categorize adrenal masses as benign nonhypersecretory adenomas (the vast majority) vs. a possibly malignant lesion (the minority). In the presence of normal biochemistry, a concordant NP-59 imaging pattern is diagnostic of a nonhypersecretory benign adrenal adenoma and requires no immediate therapeutic intervention. Conversely, patients with discordant patterns of NP-59 scintigraphy have lesions that carry a significant risk for malignancy, and the pursuit of a tissue diagnosis is indicated, usually by means of FNA. Normal adrenocortical tissue on cytological studies in this setting may represent inadvertent sampling of adjacent normal adrenocortical tissues or the presence of a well differentiated adrenocortical carcinoma. In patients with lesions larger than 2 cm in whom NP-59 scintigraphy is nonlateralizing, the possibility of a periadrenal or pseudoadrenal mass is likely and should prompt review, or perhaps even repeat, of high resolution adrenal imaging (occasionally angiography may be helpful). In lesions shown to be 2 cm or less in size with a nonlateralizing NP-59-scan, there is a possibility of a periadrenal or pseudoadrenal mass; however, once this is excluded it must be recognized that benign and malignant lesions, because of the limitations of scintigraphy, cannot always be clearly distinguished by this method when masses are small.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Gland Diseases↗
PubMed1995

Biochemical markers of bone turnover in lactating and nonlactating postpartum women.

We measured two bone-formation markers, osteocalcin and bone-specific alkaline phosphatase, and one bone-resorption marker, N-telopeptide, in a longitudinal study in order to describe levels of these markers in lactating and nonlactating women after parturition. This 18-month postpartum period included an initial 6 months in which a 5% short-term bone loss occurred at both spine and femoral neck among breast-feeding women. The second part of the 18-month period was characterized by bone recovery among women who had lost bone. These bone-change characteristics provided an opportunity to evaluate the performance of biochemical markers during both bone loss and recovery and to identify environmental exposures during lactation associated with bone turnover. The eligible population comprised 115 women whose bone-turnover markers were measured at 2 weeks (baseline) and at 2, 4, 6, 12, and 18 months after parturition. Participants reported reproductive characteristics, diet, physical activity, use of medications, and infant-feeding practices at each contact. Women were grouped according to lactation duration: 0-1 months, 2-5 months, and 6 months or more. Women who breast-fed for at least 6 months had significantly different levels of all three bone-turnover markers compared with the levels in bottle-feeding controls, which were indicative of substantially increased bone turnover. Factors that predicted the difference in biochemical markers from baseline to 6-month values by regression analysis were lactation of 2-6 months duration and lactation for 6 months or more. Dietary calcium intake, physical activity level, and body size did not explain the differences in the change from the baseline level to the 6-month level, a period of time that corresponded with bone loss in the lactating women. Factors that predicted the differences in bone-turnover markers between 6 and 18 months (the time of bone-mass recovery) were lactation status and number of months to resumption of menses. By the 18-month observation, there was no difference in the mean values for the measured bone-turnover markers among the three lactation groups. This suggests that menstrual activity, rather than diet or physical activity, is the primary factor in bone-mass recovery after the bone loss of lactation.

Adult↗
PubMed1995

The current status of meta-iodobenzylguanidine and related agents for the diagnosis of neuro-endocrine tumors.

Metaiodobenzylguanidine (MIBG) has been in clinical use for 15 years and has been shown to have high sensitivity (about 85%) and specificity (> 95%) for the location of all types of pheochromocytomas. Similar results have been achieved with neuroblastomas. A wide range of other neuroendocrine lesions including carcinoids, medullary thyroid cancer and nonsecretory paragangliomas may also be imaged, but the lower sensitivity. The newly developed radiolabeled somatostatin analogs may have greater utility for these lesions. MIBG scintigraphy may also provide a unique in vivo probe for study of the sympathetic autonomic nervous system, particularly in the heart. Various radiolabels for MIBG and its analogs permit planar scintigraphy, SPECT, PET, intraoperative probe localization and radiopharmaceutical therapy.

3-Iodobenzylguanidine↗
PubMed1995

The current status of radioiodinated metaiodobenzylguanidine therapy of neuro-endocrine tumors.

The avidity of many metastatic pheochromocytomas and neuroblastomas for metaiodobenzylguanidine (MIBG) observed at diagnostic scintigraphy has led to attempts to treat these lesions with large doses of MIBG. We and others have achieved therapeutic responses with 131I-MIBG (usually partial) in about a third of malignant pheochromocytomas. A small but important subgroup of advanced, poor prognosis neuroblastomas which have been resistant to all other therapies have also shown responses including occasional long-term survival (> 5 years) and apparent complete responses to 131I-MIBG. Because the physical properties of 131I are suboptimal for the delivery of therapeutic radiation to bone marrow micrometastases, a frequent problem in neuroblastoma, we have performed preliminary studies in poor prognosis Stage III and VI neuroblastoma using 125I-MIBG which has more satisfactory emissions. This has led to prolonged tumor stabilization and survival (> 19 to > 52 months) in 5 of 10 patients. MIBG radiopharmaceutical treatment of neuroendocrine tumor patients must still be considered an experimental but nevertheless promising treatment modality.

3-Iodobenzylguanidine↗
PubMed1995

Ten years of experience with MIBG applications and the potential of new radiolabeled peptides: a personal overview and concluding remarks.

The international workshop on metaiodobenzylguanidine (MIBG) and radiolabeled somatostatin analogs held in Rome in June, 1994 addressed a wide range of topics which might be classified into five broad general themes: Theme 1. The role of MIBG for the location of neuroendocrine tumors. A) The range of tumors in which MIBG scintigraphy is effective (pheochromocytomas, neuroblastoma, chemodectoma and other APUDomas). B) The increasing popularity of 123I as a radiolabel for MIBG (potential advantages in planar and SPECT imaging). C) MIBG as the prototype of a family of radiopharmaceuticals exploiting the biogenic amine uptake and storage mechanisms. (Other radiohalides 124I, 125I, 87Br, 211At, 18F; other PET radiopharmaceuticals such as 11C-epinephrine, 11C-hydroxyephedrine). Theme 2. The role of MIBG as an in vivo scintigraphic probe of the sympathetic nervous system. A) Cardiac sympathetic innervation (in cardiomyopathy, myocardial infarction, and as a prognostic index for cardiac transplantation). B) Pulmonary MIBG uptake as index of pulmonary endothelial/sympathetic function (MIBG by both the intravenous and inhaled routes of administration). Theme 3. MIBG for the radiopharmaceutical therapy of neuroendocrine tumors. A) Treatment of neuroblastoma early in the natural history of the disease (MIBG therapy as initial management, MIBG therapy combined with other modalities--e.g., chemotherapy and bone marrow transplantation). Theme 4. The role of radiolabeled somatostatin analogs for the location of neuroendocrine and other tumors. A) The range of tumors in which somatostatin receptor radiopharmaceutical scintigraphy is effective (pituitary tumors, central nervous system tumors, carcinoids, islet cell tumors, medullary thyroid carcinoma, small cell lung cancer, APUDomas). B) The superiority of 111In over 123I as a radiolabel (the future of potential 99mTc and other labels). C) Somatostatin receptor scintigraphy in autoimmune and other disorders. D) Pentetreotide as the prototype of a wide range of radiolabeled peptides as radiopharmaceuticals for the in vivo depiction of the receptors for peptide hormones, lymphokines, paracrine and other information transmitting molecules (the general concepts include the use of long-acting, slowly degraded analogs and the development of generally applicable labeling techniques. Examples include 123I-ANF, labeled interleukins and other lymphokines). Theme 5. Comparisons of MIBG and pentetreotide scintigraphy for the location of neuroendocrine tumors. A) The range of neuroendocrine and other tumors (e.g., pheochromocytomas, neuroblastomas, carcinoids, islet cell tumors and other APUDomas).

3-Iodobenzylguanidine↗
PubMed1994

Localization of parathyroid enlargement: experience with technetium-99m methoxyisobutylisonitrile and thallium-201 scintigraphy, ultrasonography and computed tomography.

Technetium-99m methoxyisobutylisonitrile (MIBI), like thallium-201, has recently been introduced as a myocardial perfusion agent and is now also showing very promising results in parathyroid scintigraphy. The results of 201Tl/99mTc-pertechnetate and 99mTc-MIBI/99mTc-pertechnetate subtraction scintigraphy, ultrasonography and computed tomography are presented in a series of 43 patients operated on for hyperparathyroidism. All four imaging modalities were confirmed to be reliable, scintigraphy being the most accurate. Sensitivities ranged from 81% to 95%, that of 99mTc-MIBI being the highest. Moreover this tracer, which has more favourable physical and also biochemical properties, yielded images of superior quality. This allowed localization of the lesion by visual inspection only in as many as 86% of the patients with positive 99mTc-MIBI/99MTc-pertechnetate subtraction scintigraphy. We believe that the higher sensitivity, superior image quality and lower cost of 99mTc-MIBI imaging will make 99mTc-MIBI the new radiopharmaceutical of choice for parathyroid scintigraphy (when one take into account the stability of labelling with large activities it is possible to perform three or four cardiac studies together with one parathyroid scintigraphic examination using one lyophilized vial).

Adenoma↗
PubMed1994

Predictors of toxicity in treating patients with neuroblastoma by radiolabeled metaiodobenzylguanidine.

We searched for methods that would enable prescriptions of the maximum tolerable doses of iodine-131 metaiodobenzylguanidine (MIBG) and iodine-125 MIBG in the treatment of patients with neuroblastoma. We correlated doses, defined in different ways, with subsequent platelet levels in treated patients to determine accurate predictors of the most frequent toxicity, thrombocytopenia. Nine patients with neuroblastoma were given 131I-MIBG (4.9-8.1 GBq or 132-220 mCi) and ten were given 125I-MIBG (8.3-30.0 GBq or 224-809 mCi) as initial treatments. These therapies were sufficiently varied that correlations could be made between indices of the doses and the subsequent toxicity as reflected in circulating platelet levels. Predictors of toxicity were: whole-body absorbed dose of radiation (cGy) calculated from pretherapy tracer doses of 131I-MIBG; GBq/kg of body weight; and GBq/m2 of body surface area. Toxicity was recorded as the nadir of the platelet level and platelet/pretherapeutic level (platelet ratio). For treatments with 131I-MIBG, the highest correlation was obtained between cGy and the log10-transformed platelet ratio (r = -0.86), but comparison of GBq/m2 and the platelet nadir (r = -0.76) or the platelet ratio (r = -0.74) or the log10 transformed platelet ratio (r = -0.73) gave comparable and statistically significant results. For treatments with 125I-MIBG, significant correlations were obtained between GBq/m2 and the platelet ratio (r = -0.81) or GBq/kg and the log10-transformed platelet ratio; the correlation between cGy and any toxicity index was low. Per administered GBq, 131I-MIBG was 2.6 times more potent than 125I-MIBG in causing a platelet ratio of 0.1.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Iodobenzylguanidine↗
PubMed1994

Interference by spironolactone on adrenocortical scintigraphy and other pitfalls in the location of adrenal abnormalities in primary aldosteronism.

A case of primary aldosteronism is presented in which the CT scan was initially misleading, adrenocortical scintigraphy was rendered inaccurate by pharmacological interference of spironolactone, and selective adrenal venous sampling of aldosterone was technically difficult. When dexamethasone suppression adrenocortical scintigraphy was performed with attention to technical detail and exclusion of interference by spironolactone, the causative lesion was scintigraphically demonstrated. This finding was confirmed by the results of venous sampling and the correctly located tumor removed.

Adosterol↗
PubMed1994

Concurrent Plummer's disease and parathyroid adenoma. Diagnostic and therapeutic approaches to a difficult clinical problem.

When mild asymptomatic hypercalcemia occurs in a patient with hyperthyroidism, it may or may not be due to concurrent hyperparathyroidism and at times only the control of the hyperthyroidism will resolve the problem. Moreover, the presence of hyperfunctioning thyroid nodules will interfere with Tl-201/Tc-99m pertechnetate parathyroid scintigraphy. Initial treatment of hyperthyroidism with I-131 in this situation controls hyperthyroidism and permits successful localization of parathyroid adenomas, which may then be excised--a result that was achieved in three cases.

Adenoma↗
PubMed1994

An unusual false-positive scan in a patient with pericardial effusion.

Uptake of I-131 in the pericardial area is described in an asymptomatic patient who underwent total body scan for recurrent papillary thyroid cancer. Ultrasonography demonstrated a small pericardial effusion that persisted after I-thyroxine therapy was reinstituted. Two I-131 therapeutic doses were given, and follow-up total body scans were performed during the next 6 years. Although tracer accumulation in the neck was eliminated and the serum thyroglobulin level was not elevated, I-131 uptake persisted in pericardial effusion. Despite diligent study, no neoplastic, infectious, or autoimmune etiology could be demonstrated, and we thus classified it as idiopathic pericardial effusion. This phenomenon should be considered when interpreting I-131 scans that show I-131 uptake in the region of the heart.

Carcinoma, Papillary↗
PubMed1994

Locating neuroblastoma in the opsoclonus-myoclonus syndrome.

We examined the role of various medical imaging modalities, particularly metaiodobenzylguanidine (MIBG) scintigraphy in the investigation of patients presenting with the opsoclonus-myoclonus syndrome (OMS) who may harbor neuroblastomas. A retrospective analysis was therefore performed of all patients presenting with OMS in a 5 1/2 year period. Between December, 1988 and May, 1994, all 13 patients (mean age 15.2 months, range 3 days-30 months) presenting with OMS were extensively studied. A wide range of medical imaging modalities including CT, MRI and [131I] or [123I]-metaiodobenzylguanidine (MIBG) scintigraphy (total of 21 scans) were examined as a means of detecting a structural brain lesion or locating a neuroblastoma, a tumor generally found in less than half of patients with OMS. As anticipated a minority of patients (4) were eventually found to harbor neuroblastomas. In these four cases, two tumors were revealed on preoperative MIBG scintigraphy, one gave a false negative study and one tumor was not studied preoperatively. Each patient was also subjected to extensive radiological investigations in addition to MIBG scintigraphy, many of which were repetitive, redundant or had low clinical yield. The relative merits of the various procedures are compared, and an algorithm incorporating MIBG scintigraphy and limited central nervous system and abdominal anatomical modalities for the investigation of opsoclonus-myoclonus is suggested.

3-Iodobenzylguanidine↗