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Biomedical subjects

S Rubin

Publications and source records attributed to S Rubin.

At least 37 records · Page 2Linked to original sources
PubMed1999

Acute lymphoblastic leukemia with multiple cytogenetic abnormalities secondary to treatment of Ewing's sarcoma.

We report the case of a 22-year-old man with Ewing's sarcoma who attained a complete remission (CR) after combination radiotherapy and chemotherapy. Secondary acute lymphoblastic leukemia with multiple cytogenetic abnormalities involving chromosome 5 and 7 developed 16 years later. The patient underwent induction chemotherapy and entered a CR. Peripheral blood stem cell transplantation from a matched sibling was performed successfully and he is in complete remission of both ALL and Ewing's sarcoma.

Adult↗
PubMed1999

Time course of word identification and semantic integration in spoken language.

The minimum duration signal necessary to identify a set of spoken words was established by the gating technique; most words could be identified before their acoustic offset. Gated words were used as congruous and incongruous sentence completions, and isolation points established in the gating experiment were compared with the time course of semantic integration evident in event-related brain potentials. Differential N400 responses to contextually appropriate and inappropriate words were observed about 200 ms before the isolation point. Semantic processing was evident before the acoustic signal was sufficient to identify the words uniquely. Results indicate that semantic integration can begin to operate with only partial, incomplete information about word identity. Influences of semantic constraint, word frequency, and rate of presentation are described.

Adolescent↗
PubMed1999

Transport of thiamine in human intestine: mechanism and regulation in intestinal epithelial cell model Caco-2.

The present study examined the intestinal uptake of thiamine (vitamin B(1)) using the human-derived intestinal epithelial cells Caco-2 as an in vitro model system. Thiamine uptake was found to be 1) temperature and energy dependent and occurred with minimal metabolic alteration; 2) pH sensitive; 3) Na(+) independent; 4) saturable as a function of concentration with an apparent Michaelis-Menten constant of 3.18 +/- 0.56 microM and maximal velocity of 13.37 +/- 0.94 pmol. mg protein(-1). 3 min(-1); 5) inhibited by the thiamine structural analogs amprolium and oxythiamine, but not by unrelated organic cations tetraethylammonium, N-methylnicotinamide, and choline; and 6) inhibited in a competitive manner by amiloride with an inhibition constant of 0.2 mM. The role of specific protein kinase-mediated pathways in the regulation of thiamine uptake by Caco-2 cells was also examined using specific modulators of these pathways. The results showed possible involvement of a Ca(2+)/calmodulin (CaM)-mediated pathway in the regulation of thiamine uptake. No role for protein kinase C- and protein tyrosine kinase-mediated pathways in the regulation of thiamine uptake was evident. These results demonstrate the involvement of a carrier-mediated system for thiamine uptake by Caco-2 intestinal epithelial cells. This system is Na(+) independent and is different from the transport systems of organic cations. Furthermore, a CaM-mediated pathway appears to play a role in regulating thiamine uptake in these cells.

Biological Transport↗
PubMed1999

Assessment of infant cardiopulmonary resuscitation rescue breathing technique: relationship of infant and caregiver facial measurements.

OBJECTIVE: Although a few infants ever require resuscitation, pediatric cardiopulmonary resuscitation (CPR) is performed most commonly under 1 year of age. American Heart Association guidelines for pediatric basic life support recommend that the caregiver place his/her mouth over the infant's mouth and nose to create a seal. The way CPR is currently taught encourages parents to attempt to seal the nose and open the mouth of the infant for rescue breathing. Recent studies suggest some parents may have trouble sealing an infant's nose and open mouth, but their study participant numbers were small. The aim of this report is to estimate, among a large cohort, the ability of caregivers to create a seal to their infants for the provision of rescue breathing according to current guidelines. METHODS: Infants up to 1 year of age (n = 281) and their caregivers were enrolled from Philadelphia pediatric offices. Facial measurements of the infants were obtained to estimate the length needed to seal the nose and open mouth, and the nose and closed mouth. Mouth widths of the caregivers were compared with their infant's nose and mouth lengths. One-way analysis of variance with Tukey's postmortem analysis and ordinary least squares means regression were used for univariate analysis with analysis of covariance used to control for the effects of multiple variables when necessary. Infant measurements were stratified into 3-month age quadrants to compare against matched adult caregiver measurements. RESULTS: Most caregivers (n = 270) were female. Females had smaller mouth widths than males (4.9 +/- 0.5 cm vs 5.2 +/- 0.5 cm). Infant nose and mouth length increased during the first year of life, with the largest increase between 0 to 3 months and 3 to 6 months (4.2 +/- 0.4 cm to 4.7 +/- 0.4 cm). As infant age and face length increased, a progressively higher rate of adult females were estimated not to be able to cover their infant's nose and open mouth, with the greatest increase again between 0 to 3 months (9%) and 3 to 6 months (40%). All female caregivers except 1 were predicted to be able to seal their infant's nose and closed mouth by our measurements. CONCLUSIONS: Infant face length grows rapidly during the first year of life with the most rapid growth occurring during the first 6 months. As early as 3 to 6 months of infant age, many adult caregivers' facial measurements, especially female, predict that they may not be able to form a seal for mouth-to-nose and open-mouth infant rescue breathing. By related measurements, nearly 100% of caregivers should be able to seal their infant's nose and closed mouth. If facial measurement predictions correlate with functional inability to seal an infant's nose and open mouth, infant CPR rescue breathing instruction will need to emphasize head position and creation of a seal over the mouth and nose without teaching that the mouth be open. pediatric basic life support, infant CPR, rescue breathing, sudden infant death syndrome, acute life-threatening episode.

Adult↗
PubMed1999

Chronic pain in the dental patient.

This article reviews the pathophysiology and mediators of pain, and addresses the different subtypes of dental pain. An overview of pharmacotherapy is presented. Contributing factors to chronic pain syndromes are reviewed. Alternative methods of pain management are discussed.

Chronic Disease↗
PubMed1998

Biotin uptake by human colonic epithelial NCM460 cells: a carrier-mediated process shared with pantothenic acid.

Previous studies showed that the normal microflora of the large intestine synthesizes biotin and that the colon is capable of absorbing intraluminally introduced free biotin. Nothing, however, is known about the mechanism of biotin absorption in the large intestine and its regulation. To address these issues, we used the human-derived, nontransformed colonic epithelial cell line NCM460. The initial rate of biotin uptake was found to be 1) temperature and energy dependent, 2) Na+ dependent (coupling ratio of 1:1), 3) saturable as a function of concentration [apparent Michaelis constant (Km) of 19.7 microM], 4) inhibited by structural analogs with a free carboxyl group at the valeric acid moiety, and 5) competitively inhibited by the vitamin pantothenic acid (inhibition constant of 14.4 microM). Pretreatment with the protein kinase C (PKC) activators phorbol 12-myristate 13-acetate (PMA) and 1, 2-dioctanoyl-sn-glycerol significantly inhibited biotin uptake. In contrast, pretreatment with the PKC inhibitors staurosporine and chelerythrine led to a slight, but significant, increase in biotin uptake. The effect of PMA was mediated via a marked decrease in maximal uptake velocity and a slight increase in apparent Km. Pretreatment of cells with modulators of the protein kinase A-mediated pathway, on the other hand, showed no significant effect on biotin uptake. These results demonstrate, for the first time, the functional existence of a Na+-dependent, specialized carrier-mediated system for biotin uptake in colonic epithelial cells. This system is shared with pantothenic acid and appears to be under the regulation of an intracellular PKC-mediated pathway.

Alkaloids↗
PubMed1997

Dysplastic nitrergic neurons in the rectum of a patient with rectal ectasia.

We present a histochemical study of resected colon from a 13-year-old boy diagnosed with rectal ectasia. Laminar preparations and sectioned tissue of rectum were assayed histochemically for nitric oxide (NO) synthase activity by reducing nitro blue tetrazolium salt in the presence of the cofactor NADPH. Tissue preparations displayed intensely labelled neurons and fibers throughout the gut wall. Laminar preparations of Meissner's plexus showed a hyperplasia of ganglia and NO-related neurons throughout the length of the resected rectum compared with normal bowel. Sectioned tissue of the Auerbach's plexus demonstrated a normal number of ganglia and NO-related neurons. As well, the ectatic bowel showed a proliferation of nerve fibers in keeping with the degree of circular smooth muscle hypertrophy. This proliferation may represent a reactive phenomenon secondary to the functional obstruction. The NO histochemical technique may form the basis of further investigations in defining the cause of this functional obstruction.

Adolescent↗
PubMed1997

Minimum urine flow rate during water deprivation: importance of the nonurea versus total osmolality in the inner medulla.

Antidiuretic hormone leads to an increase in the permeability for water and urea in the inner medullary collecting duct. Hence, urea may not be an "effective" osmole in the inner medulla during maximal renal water conservation. Accordingly, the purpose of this study was to evaluate whether differences in the rate of urea excretion would influence maximum renal water conservation in humans. In water-deprived rats, the concentration of urea and total osmolality were somewhat higher in the urine exiting the inner medullary collecting duct than in interstitial fluid obtained from the entire papillary tip. Nevertheless, the "nonurea" (total osmolality minus urea in millimolar terms) osmolality was virtually identical in both locations. Chronically fasted human subjects that were water-deprived for 16 h had a lower rate of urea excretion (71 +/- 7 versus 225 +/- 14 mumol/min) and a somewhat lower urine osmolality (745 +/- 53 versus 918 +/- 20 mosmol/kg H2O). Nevertheless, they had identical urine flow rates (0.5 +/- 0.01 and 0.5 +/- 0.02 ml/min, respectively), and their nonurea osmolality also was similar (587 +/- 25 and 475 +/- 14 mosmol/kg H2O, respectively) to the water-deprived normal subjects. The composition of their urine differed in that the principal nonurea osmoles became NH4+ and beta-hydroxybutyrate rather than Na and C1. During water deprivation in normal subjects, the ingestion of urea caused a twofold rise in urine flow rate, a fall in the nonurea osmolality, and a rise in the rate of excretion of nonurea osmoles. The nonurea osmolality of the urine, and presumably the medullary interstitial fluid as well, was inversely related to the urea excretion rate. In chronic fasting, the nature, but not the quantity, of nonurea osmoles changed. The similar minimum urine volume was predictable from an analysis based on nonurea osmole considerations.

Administration, Oral↗
PubMed1996

Lower diagnostic accuracy of thallium-201 SPECT myocardial perfusion imaging in women: an effect of smaller chamber size.

OBJECTIVES: We attempted to formally compare the diagnostic accuracy of thallium-201 single-photon emission computed tomographic (SPECT) myocardial perfusion imaging in men and women and the effect of chamber size on accuracy. BACKGROUND: The diagnostic accuracy of conventional exercise testing has been shown to be lower in women. Less is known about the relative accuracy of perfusion imaging. Because of smaller body size, women have a smaller heart size than men, a factor that may reduce accuracy. METHODS: We identified 323 patients undergoing thallium-201 SPECT myocardial perfusion imaging who either had < 5% probability of coronary artery disease (CAD) by Bayesian analysis or who underwent cardiac catheterization within 60 days of stress testing. Patients with documented history of infarction, coronary artery bypass grafting, pathologic Q waves on the electrocardiogram, left bundle branch block or nonischemic cardiomyopathy were not included. We performed strict quantitative analysis, and receiver operating characteristic (ROC) curves were generated and the area under the curve was calculated for men and women. A size index was generated from the number of short-axis slices and average radius of each slice, and the group was classified as having a large or a small chamber size. The ROC areas of men and women with a large and a small chamber size were then compared. RESULTS: Diagnostic accuracy was lower in women than in men (ROC are 0.82 vs. 0.93, p < 0.05) despite similar values for peak heart rate and rate-pressure product and similar severity of CAD. There was a greater difference in accuracy between patients with a large versus a small chamber size (ROC area 0.94 vs. 0.73, p < 0.01) despite similar levels of exercise and severity of CAD. When we compared men and women in groups stratified by chamber size, we could not detect a significant difference between ROC area values of men and women (large: 0.94 men, 0.93 women, p = 0.77, power to detect difference in area of 0.15 = 91%; small: 0.79 men, 0.72 women, p = 0.58, power to detect difference in area of 0.15 = 35%). CONCLUSIONS: The diagnostic accuracy of thallium SPECT myocardial perfusion imaging is lower in women than in men. Most of the difference appears to be due to smaller left ventricular chamber size in women, although a small residual gender effect in smaller heart sizes cannot be entirely excluded. It is proposed that the most likely cause for this difference is the relatively greater effect of imaging blurring on smaller hearts.

Aged↗
PubMed1996

The relationship of thoracic lymphadenopathy to pulmonary interstitial disease in diffuse and limited systemic sclerosis: CT findings.

OBJECTIVE: Mediastinal lymphadenopathy is frequently associated with interstitial lung disease (ILD) in patients with systemic sclerosis (SSc). This study compared the extent of lymphadenopathy in diffuse and limited SSc with the presence and type of ILD found on CT scans. SUBJECTS AND METHODS: Seventy-three patients with diffuse and limited SSc underwent thoracic CT. The presence of lymphadenopathy was correlated with the frequency and type of ILD. RESULTS: Fifty-eight percent (18/31) of patients with diffuse cutaneous SSc and 40% (17/42) of patients with limited cutaneous SSc had lymphadenopathy. A significant relationship was found between lymphadenopathy and the presence of interstitial disease (p = .0002). Seventy-two percent (18/25) of patients with a ground-glass parenchymal pattern of interstitial disease and 74% (14/19) of patients with a honeycomb pattern had lymphadenopathy. CONCLUSION: Lymphadenopathy is prevalent in patients with SSc and ILD regardless of clinical subtype or interstitial pattern. Lymphadenopathy appears to increase as a function of the profusion rather than the morphology of ILD.

Female↗