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Biomedical subjects

R Rao

Publications and source records attributed to R Rao.

At least 19 recordsLinked to original sources
PubMed2026

Surgical Management of Young Women with High-Risk Breast Cancer Receiving Neoadjuvant Systemic Therapy on the I-SPY2 Trial.

BACKGROUND: Mastectomy rates in women with breast cancer are higher in younger women than in older women. The impact of this more extensive surgery on overall survival (OS) and locoregional recurrence in younger women is unknown, especially after neoadjuvant systemic therapy (NST). This study evaluated surgical management and outcomes of patients aged &#x2264; 45 versus > 45 years enrolled in multicenter NST clinical trial, I-SPY2.0 (NCT01042379, PMID 37325931). METHODS: We conducted a secondary data analysis comparing locoregional treatment in patients aged &#x2264; 45 versus > 45 years with clinical or molecular high-risk clinical stage II-III breast cancer treated from April 2010 to June 2022. Multivariate Cox proportional hazards models were used to evaluate associations between type of breast surgery with OS and locoregional recurrence-free interval by age group and tumor receptor subtype. RESULTS: Of 1737 patients, 698 (40.2%) were aged &#x2264; 45 years. There were no significant differences in patient or tumor characteristics or residual cancer burden distribution between age groups. Although breast-conserving surgery was significantly less common in younger women (36.8% vs 48.5%, p < 0.001), surgery type was not associated with OS or locoregional recurrence-free interval for patients aged &#x2264; 45 years. CONCLUSIONS: Greater extent of breast surgery was not associated with improved outcomes in women aged &#x2264; 45 years. Choice of surgical procedure in the management of breast cancer is multifactorial, but young age alone&#xa0;does not warrant mastectomy following NST.

Breast cancer↗
PubMed2000

Phenotypic screening of mutations in Pmr1, the yeast secretory pathway Ca2+/Mn2+-ATPase, reveals residues critical for ion selectivity and transport.

Thirty-five mutations were generated in the yeast secretory pathway/Golgi ion pump, Pmr1, targeting oxygen-containing side chains within the predicted transmembrane segments M4, M5, M6, M7, and M8, likely to be involved in coordination of Ca(2+) and Mn(2+) ions. Mutants were expressed in low copy number in a yeast strain devoid of endogenous Ca(2+) pumps and screened for loss of Ca(2+) and Mn(2+) transport on the basis of hypersensitivity to 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and Mn(2+) toxicity, respectively. Three classes of mutants were found: mutants indistinguishable from wild type (Class 1), mutants indistinguishable from the pmr1 null strain (Class 2), and mutants with differential sensitivity to BAPTA and Mn(2+) toxicity (Class 3). We show that Class 1 mutants retain normal/near normal properties, including (45)Ca transport, Golgi localization, and polypeptide conformation. In contrast, Class 2 mutants lacked any detectable (45)Ca transport; of these, a subset also showed defects in trafficking and protein folding, indicative of structural problems. Two residues identified as Class 2 mutants in this screen, Asn(774) and Asp(778) in M6, also play critical roles in related ion pumps and are therefore likely to be common architectural components of the cation-binding site. Class 3 mutants appear to have altered selectivity for Ca(2+) and Mn(2+) ions, as exemplified by mutant Q783A in M6. These results demonstrate the utility of phenotypic screening in the identification of residues critical for ion transport and selectivity in cation pumps.

ATP-Binding Cassette Transporters↗
PubMed2000

Manganese selectivity of pmr1, the yeast secretory pathway ion pump, is defined by residue gln783 in transmembrane segment 6. Residue Asp778 is essential for cation transport.

We have solubilized and purified the histidine-tagged yeast secretory pathway/Golgi ion pump Pmr1 to near homogeneity in one step, using nickel affinity chromatography. The purified pump demonstrates both Ca(2+)- and Mn(2+)-dependent ATP hydrolysis and phosphoenzyme intermediate formation in forward (ATP) and reverse (P(i)) directions. This preparation has allowed us to examine, in detail, the properties of mutations D778A and Q783A in transmembrane segment M6 of Pmr1. In phenotypic screens of Ca(2+) chelator and Mn(2+) toxicity reported separately (Wei, Y., Chen, J., Rosas, G., Tompkins, D.A., Holt, P.A., and Rao, R. (2000) J. Biol. Chem. 275, XXXX-XXXX), D778A was a loss-of-function mutant apparently defective for transport of both Ca(2+) and Mn(2+), whereas mutant Q783A displayed a differential sensitivity consistent with the selective loss of Mn(2+) transport. We show that mutant D778A is devoid of cation-dependent ATP hydrolytic activity and phosphoenzyme formation from ATP. However, reverse phosphorylation from P(i) is preserved but is insensitive to inhibition by Ca(2+) or Mn(2+) ions, which is evidence for a specific inability to bind cations in this mutant. We also show that Ca(2+) can activate ATP hydrolysis in the purified Q783A mutant, with a half-maximal concentration of 0.06 micrometer, essentially identical to that of wild type (0.07 micrometer). Mn(2+) activation of ATP hydrolysis was half-maximal at 0.02 micrometer in wild type, establishing a normal selectivity profile of Mn(2+) > Ca(2+). Strikingly, Mn(2+)-ATPase in the Q783A mutant was nearly abolished, even at concentrations of up to 10 micrometer. These results were confirmed in assays of phosphoenzyme intermediates. Molecular modeling of the packing between helices M4 and M6 suggests that residue Gln(783) in M6 may form a critical hydrophobic interaction with Val(335) in M4, such that the Ala substitution modifies the packing or tilt of the helices and thus the ion pore. The data emphasize the critical role of transmembrane segment M6 in defining the cation binding pocket of P-type ATPases.

ATP-Binding Cassette Transporters↗
PubMed2000

Simultaneous determination of acidic and non-acidic pesticides in natural waters by liquid chromatography-mass spectrometry.

There is increasing interest and demand for real multi-residue methods able to simultaneously determine pesticides with a broad spectrum of chemical characteristics in environmental and biological matrices. A method based on solid-phase extraction with a Carbograph 4 cartridge and liquid chromatography with electrospray mass spectrometry (LC-ES-MS) enabling simultaneous determination of non-acidic and acidic pesticides in real water samples is described. On repeatedly (n=5) extracting 4 l of drinking water (spike level 50 ng/l), 2 l of ground water (spike level 100 ng/l) and 1 l of river water (spike level 200 ng/l), recovery of 26 base/neutral pesticides and 13 acidic pesticides were equal to or better than 80%, except for carbendazim (67%), butocarboxim (73%), aldicarb (75%) and molinate (77%). Relative standard deviations ranged between 4 and 15%. Final extracts containing acidic and non-acidic pesticides were analyzed in a single chromatographic run while the ES-MS system was operated in both positive and negative ion modes. With the aim of finding the best operating conditions, in terms of sensitivity, the pH of the LC eluent was varied in the 2.9-8.4 range. Altogether, the best results were obtained by using an LC eluent containing 1 mmol/l formic acid. Over the entire pH range considered, well shaped peaks for both basic and acidic analytes were achieved by the use of a new generation LC column. By extracting selected ion current profiles from the total ion current mass chromatogram relative to analysis of 4 l of drinking water spiked with 50 ng/l of each of the 39 analytes, estimated limits of detection ranged between 0.05 and 1.5 ng/l, except for propyzamide (8 ng/l) and 2,4-DB (3 ng/l).

Acids↗
PubMed2000

A search for susceptibility loci for anorexia nervosa: methods and sample description.

BACKGROUND: Eating disorders have not traditionally been viewed as heritable illnesses; however, recent family and twin studies lend credence to the potential role of genetic transmission. The Price Foundation funded an international, multisite study to identify genetic factors contributing to the pathogenesis of anorexia nervosa (AN) by recruiting affective relative pairs. This article is an overview of study methods and the clinical characteristics of the sample. METHODS: All probands met modified DSM-IV criteria for AN; all affected first, second, and third degree relatives met DSM-IV criteria for AN, bulimia nervosa (BN), or eating disorder not otherwise specified (NOS). Probands and affected relatives were assessed diagnostically with the Structured Interview for Anorexia and Bulimia. DNA was collected from probands, affected relatives and a subset of their biological parents. RESULTS: Assessments were obtained from 196 probands and 237 affected relatives, over 98% of whom are of Caucasian ancestry. Overall, there were 229 relative pairs who were informative for linkage analysis. Of the proband-relative pairs, 63% were AN-AN, 20% were AN-BN, and 16% were AN-NOS. For family-based association analyses, DNA has been collected from both biological parents of 159 eating-disordered subjects. Few significant differences in demographic characteristics were found between proband and relative groups. CONCLUSIONS: The present study represents the first large-scale molecular genetic investigation of AN. Our successful recruitment of over 500 subjects, consisting of affected probands, affected relatives, and their biological parents, will provide the basis to investigate genetic transmission of eating disorders via a genome scan and assessment of candidate genes.

Adult↗
PubMed2000

Personality disorders among subjects recovered from eating disorders.

OBJECTIVE: Personality disorders are common in symptomatic eating disorders subjects. Because personality symptoms could be exaggerated by malnutrition or Axis I disorders, we studied women who had recovered from eating disorders for at least 1 year to see if personality disorder symptoms persisted in the well state. METHOD: Personality disorders were evaluated in 10 women recovered from anorexia nervosa (AN), 28 women recovered from bulimia nervosa (BN), and 16 women recovered from AN and BN, using the Structured Clinical Interview for DSM-III-R personality disorders. RESULTS: Fourteen of 54 subjects (26%) met the criteria for at least one personality disorder, such as self-defeating, obsessive-compulsive, or borderline personality disorder. Cluster B personality disorders were closely associated with bulimic subtypes. CONCLUSIONS: While a recovery from eating disorders may have an attenuating influence on the symptoms of personality disorders, such personality disorder diagnoses persist after recovery in some recovered subjects.

Adult↗
PubMed2000

Cerebrovascular disease and late life depression: an age old association revisited.

OBJECTIVES: To examine the relationship between depression and cerebrovascular disease in three distinct settings: depression in established cerebrovascular disease, cerebrovascular disease in established depression and depression in vascular dementia. METHODS: Medline, EMBASE, PsychLit and PsychInfo databases were scanned to locate relevant articles. Data were also extracted from other articles, cited by those articles generated from the above databases. RESULTS: Using operational criteria, the prevalence of depression is higher than controls only within the first year after stroke, but most studies have not employed control groups. The prevalence of depression in vascular dementia compared with Alzheimer's disease is higher in the majority of studies, but matching for sociodemographic factors and severity of cognitive impairment has been inconsistent. An association between frontal/subcortical cerebrovascular lesions and depression in later life has been observed, but there may be methodological flaws underlying this observation in some computerized tomography studies. CONCLUSION: There is some evidence that cerebrovascular disease has an aetiopathological role in late life depression. The increased likelihood of damage to frontal/subcortical brain circuitry following stroke, transient ischaemia and hypertension may explain the high prevalence of depression in older people with vascular risk factors. More valid definitions of lesion location and the use of appropriately matched control groups would seek to clarify this issue. The extrapolation to care settings from the high prevalence of depression accompanying cerebrovascular disease and the prolongation of disability in depressed people with stroke, suggests closer liaison between old age psychiatrists, neurologists and physicians caring for the elderly.

Age Factors↗
PubMed2000

Perinatal iron deficiency decreases cytochrome c oxidase (CytOx) activity in selected regions of neonatal rat brain.

Intrauterine growth retardation and diabetes mellitus during human gestation result in significant losses of fetal and neonatal brain iron. Brain iron deficiency is associated with impaired cognitive processes including memory and attention. The regional distribution of iron staining and cytochrome c oxidase (CytOx) activity have not been mapped in the iron-sufficient or -deficient neonatal rat. CytOx is the iron-containing terminal enzyme in oxidative phosphorylation; its activity reflects neuronal metabolism. We hypothesized that neonatal brain iron deficiency differentially decreases iron and CytOx activity in brain regions, with more pronounced losses in structures involved in recognition memory. Pregnant Sprague Dawley rats were fed either an iron-deficient or -fortified diet from gestational d 1 until postnatal d 10. Iron staining and CytOx activity of 20 brain structures were mapped histochemically in 25 rats from each group. Brain iron staining was reduced from 75% to 100% and CytOx staining was decreased from 0% to 42% in the iron deficient group (p < 0.001). Areas with significantly reduced CytOx activity (p < 0.001) included all measured subareas of the hippocampus (CA1: 42%, CA3ab: 34%, CA3c: 33%, and dentate gyrus: 32%), the piriform cortex (17%), the medial dorsal thalamic nucleus (28%), and the cingulate cortex (41%). In contrast, the anterior thalamic nucleus, the lateral amygdaloid nucleus, and the medial habenula, areas not involved in higher cognitive functions, did not have significantly reduced CytOx activity (0%, 10%, and 16%, respectively). We conclude that perinatal iron deficiency differentially reduces neuronal metabolic activity, specifically targeting areas of the brain involved in memory processing.

Aging↗
PubMed2000

Tracking of familial resemblance for resting blood pressure over time in the Québec Family Study.

The etiology of familial resemblance for systolic (SBP) and diastolic (DBP) blood pressure, both within a single time point as well as across time points, was assessed to determine how familial etiologies underlying a trait may change across time. SBP and DBP measurements were taken roughly 12 years apart in family members participating in the longitudinal Québec Family Study. A longitudinal (bivariate) familial correlation model yields 3 types of correlations: intraindividual cross-time (e.g., father's BP at time 1 with his own BP at time 2); interindividual within-time (e.g., father time 1 with child time 1); and interindividual cross-time (e.g., father time 1 with child time 2). In addition, the change in BP across time (i.e., time 1-time 2) is examined using a univariate family correlation model. This combined method is useful in assessing the degree to which the same familial factors are operating across time (interindividual cross-time correlations), as well as the degree to which different heritable components are involved across time (change score). Maximal heritabilities for SBP were about 70% at each time point, while for DBP the heritability was larger at time 1 (87%) than time 2 (39%). Both the change scores (48% for SBP and 54% for DBP) and the cross-time comparisons (58% to 72% for SBP and 63% to 65% for DBP) evidenced significant familial resemblance. These results illustrate how simple methodologies can be used to specify how familial etiologies underlying a trait may change across time. For BP, the model includes unique familial factors that are specific to each time measurement, and an additional familial factor which is common to both time points. The factors leading to differences in longitudinal familial resemblance for BP (i.e., the unique factors) may be primarily genetic in origin, while those leading to stability across time may include both genetic and familial environmental effects. Sex and/or age interactions with the genotypes are also suggested.

Adult↗
PubMed1999

Antiproliferative activity of conditioned medium from lymphocytes of neuroblastoma (NB) patient and inhibition with NB serum.

Neuroblastoma (NB) is a pediatric malignancy and results in high mortality rate. Cellular immunity has been shown to play an important role in killing tumors 'in vitro'. Human lymphocytes were activated in vitro with phytohaemagglutinin (PHA) and the effect of supernatants collected at 24, 48, 72 and 96 h were tested on proliferation of human NB cell line-SK-N-MC and glioma cell line U87-MG. The SK-N-MC cells were observed to be more susceptible to the supernatants compared to U87-MG with higher inhibition of proliferation as evaluated by [3H]thymidine incorporation (P < 0.05 for 24 and 72 h and P < 0.0005 for 48 and 96 h). Conditioned medium from lymphocytes of NB patient collected at 48 and 96 h after activation inhibited proliferation (P < 0.005) of SK-N-MC cells. The presence of serum from NB patient decreased the antiproliferative activity of supernatants from normal lymphocytes and NB patient's autologous lymphocytes (P < 0.01). This preliminary data demonstrates the capability of the activation of lymphocytes from NB patient undergoing aggressive multiagent chemotherapy and controlling proliferation of tumor cells on one hand and the role of serum from NB patient in abrogating to a certain extent the effect of activated immune cells thereby protecting tumor cells, on the other hand. Both these aspects need to considered with equal importance to study mechanisms in designing strategies for immune therapies.

Blood Proteins↗
PubMed1999

Detection of Polarized CO Emission from the Molecular Outflow in NGC 1333 IRAS 4A.

We report the first interferometric detection and mapping of linearly polarized spectral line emission due to the Goldreich-Kylafis effect. Our polarization maps of the CO J=2-->1 line in the molecular outflow powered by the very young stellar system NGC 1333 IRAS 4A make it possible to define the direction of the magnetic field in the outflow. Comparison with theoretical predictions implies that the magnetic field is parallel to the polarization. Our data suggest that the deflection of the outflow may be the result of the interaction between the outflow and the magnetic field. We also detect and map the linearly polarized dust continuum emission at 1.3 mm. The polarization map of the dust continuum is roughly consistent with an hourglass magnetic field morphology; i.e., it is in agreement with theoretical models of interstellar cloud contraction with a frozen-in magnetic field. The two techniques for mapping magnetic field morphologies agree. In general, the two techniques sample different column densities, and together they allow the study of magnetic field morphology over wider areas than either technique by itself would permit.

Journal Article↗
PubMed1999

An N-terminal EF hand-like motif modulates ion transport by Pmr1, the yeast Golgi Ca(2+)/Mn(2+)-ATPase.

Pmr1, a novel member of the family of P-type ATPases, localizes to the Golgi compartment in yeast where it provides Ca(2+) and Mn(2+) for a variety of normal secretory processes. We have previously characterized Ca(2+) transport in isolated Golgi vesicles, and described an expression system for the analysis of Pmr1 mutants in a yeast strain devoid of background Ca(2+) pump activity [Sorin, A., Rosas, G., and Rao, R. (1997) J. Biol. Chem. 272, 9895-9901]. Here we show, using recombinant bacterial fusions, that an N-terminal EF hand-like motif in Pmr1 binds Ca(2+). Increasing disruptions of this motif led to progressive loss of pump function; thus, the single point mutations D51A and D53A retained pump activity but with drastic reductions in the affinity for Ca(2+) transport, while the double mutant was largely unable to exit the endoplasmic reticulum. In-frame deletions of the Ca(2+)-binding motif resulted in complete loss of function. Interestingly, the single point mutations conferred differential affinities for transport of Ca(2+) and Mn(2+) ions. Further, the proteolytic stability of the catalytic ATP-binding domain is altered by the N-terminal mutations, suggesting an interaction between these two regions of polypeptide. These studies implicate the N-terminal domain of Pmr1 in the modulation of ion transport, and may help elucidate the role of N-terminal metal-binding sites of Cu(2+)-ATPases, defective in Wilson and Menkes disease.

Amino Acid Motifs↗
PubMed1999

Induction of vacuolar Ca2+-ATPase and H+/Ca2+ exchange activity in yeast mutants lacking Pmr1, the Golgi Ca2+-ATPase.

We have analyzed Ca2+ transport activity in defined subcellular fractions of an isogenic set of wild-type and mutant yeast. The results, together with measurements of polypeptide expression levels and promoter::reporter gene activity, show that the Golgi Ca2+-ATPase, Pmr1, is the major Ca2+ pump under normal growth conditions. In the absence of Pmr1, we show a massive, calcineurin-dependent compensatory induction of the vacuolar Ca2+-ATPase, Pmc1. In addition, H+/Ca2+ exchange activity, that may be distinct from the vacuolar exchanger Vcx1, is also increased.

ATP-Binding Cassette Transporters↗
PubMed1999

Inhibition of oxidant-induced barrier disruption and protein tyrosine phosphorylation in Caco-2 cell monolayers by epidermal growth factor.

The effect of epidermal growth factor (EGF) on the H202-induced increase in paracellular permeability in Caco-2 and T-84 cell monolayers was evaluated to examine the role of EGF in intestinal mucosal protection from oxidative stress. Oxidative stress was induced by exposing cell monolayers to H2O2 or a mixture of xanthine oxidase + xanthine (XO + X). Paracellular permeability was assessed by measuring transepithelial electrical resistance (TER), sodium chloride dilution potential, and unidirectional flux of [3H]mannitol. H2O2 (0.1 to 5.0 mM) reduced TER and dilution potential and increased mannitol flux. Administration of EGF delayed H2O2 and XO + X-induced changes in TER, dilution potential, and [3H]mannitol flux. This protective effect of apically or basally administered EGF was concentration-related, with A50 (95% confidence limits) values of 2.1 (1.17 to 4.34) and 6.0 (4.37 to 8.34) nM, respectively. The EGF-mediated protection was prevented by treatment of cell monolayers with genistein (10 microM), a tyrosine kinase inhibitor. H2O2 and XO + X also induced tyrosine phosphorylation of a number of proteins in Caco-2 and T-84 cell monolayers. EGF treatment inhibited the oxidant-induced tyrosine phosphorylation of proteins, particularly those with a molecular mass of 110-220 kDa. Treatment of Caco-2 cells with anti-transforming growth factor-alpha antibodies potentiated the H2O2-induced changes in TER, dilution potential, and mannitol flux. These studies demonstrated that an EGF receptor-mediated mechanism delays oxidant-induced disruption of the epithelial barrier function, possibly by suppressing the oxidant-induced tyrosine phosphorylation of proteins.

Antibodies, Monoclonal↗
PubMed1999

The Arabidopsis thaliana proton transporters, AtNhx1 and Avp1, can function in cation detoxification in yeast.

Overexpression of the Arabidopsis thaliana vacuolar H+-pyrophosphatase (AVP1) confers salt tolerance to the salt-sensitive ena1 mutant of Saccharomyces cerevisiae. Suppression of salt sensitivity requires two ion transporters, the Gef1 Cl- channel and the Nhx1 Na+/H+ exchanger. These two proteins colocalize to the prevacuolar compartment of yeast and are thought to be required for optimal acidification of this compartment. Overexpression of AtNHX1, the plant homologue of the yeast Na+/H+ exchanger, suppresses some of the mutant phenotypes of the yeast nhx1 mutant. Moreover, the level of AtNHX1 mRNA in Arabidopsis is increased in the presence of NaCl. The regulation of AtNHX1 by NaCl and the ability of the plant gene to suppress the yeast nhx1 mutant suggest that the mechanism by which cations are detoxified in yeast and plants may be similar.

Amino Acid Sequence↗