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Biomedical subjects

D Rao

Publications and source records attributed to D Rao.

At least 37 records · Page 2Linked to original sources
PubMed1996

Reproducibility of relative dose response (RDR) test and serum retinol and retinyl ester concentrations in children after a 2-week interval.

OBJECTIVE: Reproducibility of the relative dose response test (RDR), a test designed to measure vitamin A status, was tested in 23 Belizean children, 5-8 years after 2-week interval during which no treatment was given. METHODS: As required for the RDR test, serum retinol concentrations were determined before and 5 hours after an oral dose of vitamin A. An RDR score > 14% was used as the criterion of inadequate vitamin A status. The HPLC method used to measure serum retinol concentrations also determined the concentrations of four retinyl esters. RESULTS: The RDR test was reproducible for 17 of 23 subjects: 3 scored > 14% on both tests; 14, < 14% on both. Six subjects scored > 14% on only one test. The concordance correlation coefficient (rc) for the percent change in the two tests was 0.24; for fasting serum retinol concentration, rc = 0.81. For retinyl palmitate and stearate, the esters present in highest concentrations at 5 hours, concordance correlation coefficients were 0.75 and 0.59, respectively. CONCLUSION: The failure of the RDR test to classify 26% of the subjects reproducibly reduces the usefulness of the test. In addition, the reproducibility of the retinyl ester concentrations in serum 5 hours after the retinyl palmitate dose and the relatively high concentrations in some subjects suggests that some individuals may not metabolize sufficient retinol in 5 hours to cause a maximal increase in serum retinol, resulting in an underestimation of deficiency in a population in which the RDR test is used.

Anticarcinogenic Agents↗
PubMed1996

Serum carotenoid concentrations and their reproducibility in children in Belize.

Suggestions that carotenoid-containing foods are beneficial in maintaining health have led to several studies of circulating carotenoid concentrations of adults. Because few data are available for children, we report serum carotenoid concentrations of 493 children in Belize. Carotenoid concentrations were determined as part of a survey of vitamin A status of children, most between 65 and 89 mo of age. Reproducibility was tested by collecting a second blood sample 2 wk after the first collection from a subset of children (n = 23) who consumed their habitual diet with no treatment during the interim. Predominant serum carotenoids were lutein/zeaxanthin and beta-carotene, which accounted for 26% and 24% of median total carotenoids, respectively. The three provitamin A carotenoids, alpha- and beta-carotene and beta-cryptoxanthin, constituted 51% of median total carotenoid concentrations. Partial correlations of each carotenoid with fasting retinol concentration indicated that beta-carotene had the highest correlation. Concordance correlation coefficients (rc) for fasting carotenoid concentrations determined 2 wk apart were > or = 0.89 for lycopene, beta-cryptoxanthin, and alpha- and beta-carotene. The rc for lutein/zeaxanthin and total carotenoids was lower, 0.59 and 0.68, respectively, because of higher lutein/zeaxanthin concentrations at the second sampling than at the first. The reproducibility of the concentrations suggests both that individuals have characteristic profiles and that serum carotenoid concentrations can be measured randomly over > or = 2 wk without significant bias.

Belize↗
PubMed1995

NHE-1 isoform of the Na+/H+ antiport is expressed in the rat and rabbit esophagus.

BACKGROUND & AIMS: Rabbit esophageal cells show an amiloride-sensitive Na+/H+ antiporter activity. Several distinct molecular isoforms of the Na+/H+ exchanger family (NHE) are reported to be present in the gastrointestinal tract of rats and rabbits. The aim of this study was to examine which isoforms are present in rabbit and rat esophageal cells and whether this isoform could be up-regulated by serum factors. METHODS: Specific primers designed from the rat NHE-1-4 and the rabbit NHE-1-3 isoform sequences were used for reverse-transcription polymerase chain reaction analysis with RNA from rabbit and rat esophageal cells. Ribonuclease protection assay was used to determine the serum-induced up-regulation of NHE-1. Antibodies raised against the NHE-1 C-terminal fragment were used for Western blotting with rabbit esophageal membranes. RESULTS: In both the rat and rabbit esophagus, only the NHE-1 isoform messenger RNA could be detected. The NHE-1 messenger RNA, detected in rabbit esophageal cells grown from tissue explants, was up-regulated by serum factors. The antibody detected a 95-kilodalton protein in esophageal cell membranes. CONCLUSIONS: The rabbit and rat esophagus exclusively express the NHE-1 isoform, hypothesized to be involved in cytoplasmic pH regulation. Therefore, the results of this study suggest a role for NHE-1 in protecting cells against gastric acid that is refluxed into the esophagus.

Animals↗
PubMed1995

Osteogenic sarcoma of sphenoid bone: an extended lateral skull base approach.

Osteogenic sarcoma involving the sphenoid bone is an extremely rare condition. The rarity of the disease and the close proximity of the sphenoid bone to the various important intracranial structures poses a real challenge in diagnosis and surgical management of these lesions. An extended lateral craniofacial resection by a multidisciplinary approach was carried out in one such case to attempt en bloc resection. This case is presented and also a review of the relevant literature.

Adult↗
PubMed1994

Analysis of [3H]estradiol-17beta metabolites in calf perirenal fat.

Residues of estradiol-17 beta (E2 beta) in the kidney fat of one milk-fed calf were studies using radiometric methodologies. A three-month old Friesian male veal calf was injected intramuscularly daily for 3 d with 333 mg of [6,7(n)-3H]-E2 beta (specific activity: 7.55 MBq mmol-1) dissolved in 2 ml of propylene glycol and slaughtered 3 h after the last administration. Total estrogens were about 280 ng g-1 in perirenal fat. After a de-lipidation step, the relatively polar metabolites that were extractable with dichloromethane represented the main fraction of the metabolites, which accounts for almost 50% of the total radioactivity of the tissue, of which E2 beta was the major metabolite (19.7%) and E1 and E2 alpha represented only 7.7 and 3.2%, respectively. Conjugated estrogens accounted for only 15.2% of the total estrogen content. Non-polar estrogens (about 25% of total estrogens) were removed specifically with isooctane during the de-lipidation step and were further purified on silica and alumina columns before being chromatographed by normal-phase HPLC. The radioactive metabolites were eluted as estrogen-17 esters. The HPLC analysis of the estrogens released following hydrolysis of the esters indicated that E2 beta was the main estrogen acylated by long-chain fatty acids in the fraction of lipoidal estrogens. The presence of such a class of estrogens in fat could be of interest for the detection of estrogens a considerable time after estradiol administration.

Adipose Tissue↗
PubMed1994

The effects of gender and birth control pill use on spontaneous blink rates.

BACKGROUND: Two major reference works suggest that men and women blink spontaneously at different rates, but they disagree with regard to which gender blinks faster. METHODS: Spontaneous blink rates of 59 males and 86 females, 44 of whom were taking birth control (BC) pills, were measured for 5 consecutive minutes. Schirmer test results and tear break-up times (TBUTs) were also obtained. RESULTS: Females taking BC pills blinked at a mean rate of 19.6 times per minute, females not taking birth control pills blinked 14.9 times per minute, and males blinked 14.5 times per minute. There were very large differences between blink rates for individuals in each of the groups. No strong associations were found between spontaneous blink rates and a history of contact lens use, tear break-up time, Schirmer test results, temperature or humidity in the examination room, subject age, or menstrual cycle phase. CONCLUSIONS: The 32 percent increase in mean blink rate for females taking BC pills suggests that the pills affect at least one of the mechanisms that control spontaneous blinking, but it is unclear how they accomplish this.

Adult↗
PubMed1993

Altered tau and neurofilament proteins in neuro-degenerative diseases: diagnostic implications for Alzheimer's disease and Lewy body dementias.

The neuronal cytoskeleton is one of the most profoundly altered organelles in late life neuro-degenerative disorders that are characterized by progressive impairments in cognitive abilities. The elucidation of the protein building blocks of these organelles as well as advances in understanding how these proteins become altered in Alzheimer's disease (AD) and other less common dementing illnesses, i.e., diffuse Lewy body disease (DLBD) or the Lewy body variant of AD (LBVAD), will provide insights into the molecular basis of these disorders. Within, we review evidence that normal adult human tau is abnormally phosphorylated and converted into the subunits of AD paired helical filaments (PHFs), and that Lewy bodies (LBs) represent accumulation of altered neurofilament (NF) triplet subunits. Although the precise biological consequences of PHF and LB formation in neurons is unknown, growing evidence suggests that the formation of PHFs and LBs from normal neuronal cytoskeletal proteins could have deleterious effects on neuronal function and survival. Finally, insights into the composition of PHFs and LBs could lead to the development of novel strategies for the timely and accurate diagnosis of AD, DLBD and the LBVAD.

Alzheimer Disease↗
PubMed1991

Expression of recombinant human plasminogen in mammalian cells is augmented by suppression of plasmin activity.

We present evidence that over-expression of human plasminogen, the precursor to the serine protease plasmin, can be cytotoxic to mammalian cells. When an expression vector containing plasminogen cDNA is transfected into baby hamster kidney cells, the number of drug-resistant colonies as well as the levels of plasminogen secreted by those colonies is lower than observed in similar transfections of other protease precursor genes. The recombinant plasminogen accumulates intracellularly as degraded NH2-terminal fragments. In contrast, a mutant of plasminogen that produces inactive plasmin (active site Ser740 changed to Ala) is synthesized by these cells as a full-length plasminogen molecule, and the colony numbers and expression levels are normal. Thus, the generation of plasmin activity is responsible for the cytotoxic phenomena and the degradation associated with plasminogen expression. In addition, experiments using a plasminogen mutant that cannot be activated to plasmin (activation cleavage site Arg560 to Gly) or using coexpression of antisense urokinase RNA indicate that an endogenous plasminogen activator is responsible for converting newly synthesized plasminogen to plasmin. Finally, coexpression of plasminogen with alpha 2-plasmin inhibitor, a serpin which is the physiologic inhibitor of plasmin, prevents the toxic effects of intracellular plasmin activity and allows the synthesis and secretion of native human plasminogen.

Animals↗
PubMed1990

Fibrin affinity and clearance of t-PA deletion and substitution analogues.

To investigate structure-function relationships in tissue-type plasminogen activator (t-PA) we deleted the following domains in the heavy chain: a) The epidermal growth factor domain (t-PA del. G), b) the finger domain, and the epidermal growth factor domain (t-PA del. FG), and c) the finger, the epidermal growth factor and Kringle 1 (t-PA del. FGK1). To study specifically the function of the growth factor domain we made two substitutions of d) 8 amino acids (consensus sequence) in the growth factor domain (t-PA G-CS) and e) the whole domain with factor IX growth factor domain (t-PA G-IX). Finally, f) an analogue with substitution in the finger domain (fibronectin consensus sequence) was constructed (t-PA F-CS). A reduced fibrin binding of all the analogues was found. The fibrin stimulated activity of all analogues was also reduced and correlated to the fibrin binding. In contrast, the activity of the analogues in the clot lysis assay and the plate assay were only slightly reduced as compared to authentic t-PA. This suggested that at high fibrin concentrations the decreased fibrin affinity was less critical for obtaining a high fibrinolytic activity. All analogues had a prolonged half-life in vivo as compared to authentic t-PA. The assumption of clearance mechanism involving mainly the growth factor region (or Kringle 1) was not challenged by the observation of a prolonged half-life for the substitution analogue t-PA F-CS.2+off

Amino Acid Sequence↗