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Biomedical subjects

A Chandra

Publications and source records attributed to A Chandra.

At least 91 records · Page 5Linked to original sources
PubMed1998

Surgical sterilization in the United States: prevalence and characteristics, 1965-95.

OBJECTIVES: This report presents national data on the prevalence of surgical sterilization from 1965 to 1995 among women 15-44 years of age. Data are shown by type of sterilizing operation and demographic characteristics of the women. For the 1995 survey data, reasons for the three most common sterilizing operations (tubal ligation, vasectomy, and hysterectomy) are shown, as well as the desire for reversal among those with potentially reversible operations. METHODS: Data are based on nationally representative samples of women 15-44 years of age: the 1965 National Fertility Study (NFS), and the 1973, 1982, 1988, and 1995 cycles of the National Survey of Family Growth (NSFG). RESULTS: After rising from 16 to 42 percent between 1965 and 1988, the prevalence of surgical sterilization among married women 15-44 years old remained stable at 41 percent in 1995. Age, parity, religious affiliation, and education continued to be strongly associated with overall surgical sterilization levels. Tubal ligation and vasectomy were equally prevalent in the 1965 and 1973 surveys, but since 1962, tubal ligation has been more prevalent than vasectomy. CONCLUSIONS: Several factors contributed to the rise in reliance upon surgical sterilization among women 15-44 years old over the last 3 decades: (a) aging of the post-World War II Baby Boom women (and their partners) through the primary reproductive years; (b) relatively high contraceptive failure rates, particularly among socioeconomically less advantaged women; and (c) higher expectations for contraceptive effectiveness, safety, and convenience. Overall sterilization prevalence may be leveling off among women 15-44 years old, in part due to greater delay of first and subsequent births, thus making sterilization less of a concern while women are in this age range.

Adolescent↗
PubMed1997

Modification of aldose reductase by S-nitrosoglutathione.

Kinetic and structural changes in recombinant human aldose reductase (AR) due to modification by S-nitrosoglutathione (GSNO) were investigated. Incubation of the enzyme with 10-50 microM GSNO led to a time- and concentration-dependent inactivation of the enzyme, with a second-order rate constant of 0.087 +/- 0.009 M-1 min-1. However, upon exhaustive modification, 30-40% of the enzyme activity was retained. The non-inactivated enzyme displayed a 2-3-fold change in Km for NADPH and Km fordl-glyceraldehyde, whereas the Km for the lipid peroxidation product, 4-hydroxy-2-trans nonenal (HNE), was comparable to that of the untreated enzyme. The residual activity of the enzyme after GSNO treatment was less sensitive to inhibition by the active site inhibitor sorbinil or to activation by sulfate. Significantly higher catalytic activity was retained when the enzyme was modified in the presence of NADPH, suggesting relatively low reactivity of the E-NADPH complex with GSNO. The modification site was identified using site-directed mutants in which each of the solvent-exposed cysteines of the enzyme was replaced individually by serine. The mutant C298S was insensitive to GSNO, whereas the sensitivity of the mutants C303S and C80S was comparable to that of the wild-type enzyme. Electrospray ionization mass spectroscopy of the GSNO-modified enzyme revealed a major modified species (70% of the protein) with a molecular mass that was 306 Da higher than that of the untreated enzyme, which is consistent with the addition of a single glutathione molecule to the enzyme. The remaining 30% of the protein displayed a molecular mass that was not significantly different from that of the native enzyme. No nitrosated forms of the enzyme were observed. These results suggest that inactivation of AR by GSNO is due to the selective formation of a single mixed disulfide between glutathione and Cys-298 located at the NADP(H)-binding site of the enzyme.

Aldehyde Reductase↗
PubMed1997

Active site modification of aldose reductase by nitric oxide donors.

Nitric oxide (NO) donors sodium nitrosoprusside (SNP), S-nitroso-N-acetylpenicillamine (SNAP), and 3-morpholinosydnonemine (SIN-1) caused a time- and concentration-dependent loss of catalytic activity of recombinant human placental aldose reductase. Modification of the enzyme was prevented by NADPH and NADP and reversed partially by dithiothreitol (DTT) and sodium borohydride. The protection by NADPH was lost in the presence of both substrates (NADPH and glyceraldehyde), indicating that the enzyme becomes sensitive to inhibition by SNP during catalysis. Site-directed mutant form of the enzyme, in which active site cys-298 was substituted with serine (C298S) was not inactivated by NO donors, whereas, ARC80S and ARC303 were as sensitive as the wild type enzyme, indicating that inactivation of aldose reductase is due to modification of the active site at cys298. These results suggest that NO may be an endogenous regulator of aldose reductase, and consequently the polyol pathway of glucose metabolism; which has been implicated in the pathogenesis of secondary diabetic complications.

Aldehyde Reductase↗
PubMed1997

Differential display of genome subsets containing specific interspersed repeats.

A genomic differential display method was developed that analyzes many restriction fragment length polymorphisms simultaneously. Interspersed repeat sequences were used to reduce DNA sample complexity and to target genomic subsets of interest. This work focused on trinucleotide repeats because of their importance in human inherited diseases. Immobilized repeat-containing oligonucleotides were used to capture genomic DNA fragments containing sequences complementary to the oligonucleotide. Captured fragments were amplified by PCR and fluorescently labeled using primers complementary to the repeat sequence and/or to the known sequences ligated to the ends of the restriction fragments. The labeled PCR fragments were displayed by size on a high-resolution automated fluorescent DNA sequencing instrument. Although there was a conservation in the overall pattern of displayed genome subsets, many clear and reproducible differences were detected when genomes from different individuals were compared. Fewer differences were detected within, than between, monozygotic twin pair genomes. In control experiments, the method distinguished between Huntington disease alleles with normal and expanded CAG repeat lengths.

Base Sequence↗
PubMed1997

Low molecular weight proteins secreted by peritoneal macrophages obtained from 2,3,7,8-tetrabromodibenzo-p-dioxin-treated NMRI mice.

The protein secretion patterns in a macrophage-like cell line (CBrD), established from the peritoneal cells of NMRI mice treated with the dioxin analog 2,3,7,8-tetrabromodibenzo-p-dioxin (TBrDD), were analyzed by high resolution two-dimensional gel electrophoresis (2-D PAGE), and compared to the pattern of proteins secreted by control macrophages which were intraperitoneally activated by bacterial lipopolysaccharide. The most striking alterations were observed in the low molecular range. The transformed cells encode a number of low molecular mass proteins (10-20 kDa) which were not detected in control cells under identical experimental conditions. The protein pattern with respect to isoelectric point, molecular weight, optical density (OD) and area of the spot (in mm2) has been depicted by computer analysis in relation to a standardized spot outline and the spot's background (in OD). It is concluded that the transformation of murine peritoneal macrophages by TBrDD leads to an upregulation of proteins, in particular of low-molecular-weight proteins.

Animals↗
PubMed1997

A synthesis of 4-hydroxy-2-trans-nonenal and 4-(3H) 4-hydroxy-2-trans-nonenal.

4-Hydroxy-2-trans-nonenal, the most abundant and toxic unsaturated aldehyde generated during membrane lipid peroxidation, was synthesized starting from fumaraldehyde dimethyl acetal. In the first step of the synthesis, the fumaraldehyde dimethyl acetal was partially hydrolyzed using amberlyst catalyst to obtain the monoacetal. The 4-hydroxy-2-trans-nonenal was synthesized by the Grignard reaction of the fumaraldehyde monoacetal with 1-bromopentane. 4-Hydroxy-2-trans-nonenal, obtained as its dimethylacetal, was oxidized to its corresponding 4-keto derivative using pyridinium chlorochromate buffered with sodium acetate as the oxidizing agent. 4-(3H) 4-Hydroxy-2-trans-nonenal was obtained in one step by the sodium borotriteride reduction of the 4-keto derivative.

Acetals↗
PubMed1997

Fertility, family planning, and women's health: new data from the 1995 National Survey of Family Growth.

OBJECTIVES: This report shows data on a wide range of topics from the 1995 National Survey of Family Growth (NSFG), including: pregnancy and birth, marriage, divorce, cohabitation, sexual intercourse, contraception, infertility, use of family planning and other medical services, and health conditions and behavior. METHODS: The data in this report are based on in-person interviews with a national sample of 10,847 women 15-44 years of age. The interviews lasted an average of 103 minutes. The response rate was 79 percent. The sample data are adjusted for nonresponse and are national estimates. RESULTS: Following large increases in the 1970's and 1980's, the proportion of teenagers who have ever had sexual intercourse decreased slightly between 1990 and 1995; condom use, both at first intercourse and currently, has increased markedly since the 1970's. These changes may have contributed to the decreases in the teen birth rate observed in the 1990's. For all women 15-44 years of age, the number whose partner was currently using the condom (at the date of interview) increased from 3.6 million in 1982 to 5.1 million in 1988 and 7.9 million in 1995. About 8 percent of women reported that their first intercourse was not voluntary. This result is consistent with an earlier national survey. About 20 percent reported that they had been forced by a man to have intercourse at some time in their lives. About 10 percent of births in 1990-95 were unwanted by the mother compared with 12 percent in 1984-88. The decrease in unwanted births was particularly large for black women. It appears that the prevalence of pelvic inflammatory disease (PID) and vaginal douching have both decreased since 1988.

Adolescent↗
PubMed1995

Lipid peroxidation product, 4-hydroxynonenal and its conjugate with GSH are excellent substrates of bovine lens aldose reductase.

There is increasing evidence that lipid aldehydes generated endogenously during the process of degradation of lipid peroxides, are causally involved in the pathophysiology effects associated with oxidative stress. We report here that 4-hydroxynonenal (HNE), which is one of the most abundant and toxic lipid aldehyde can be efficiently detoxified by the aldo-keto reductase, aldose reductase, purified from bovine lens. The enzyme displays a Km of congruent to 9 microM for HNE and 34 microM for the glutathione adduct of HNE (HNE-GS) assigning HNE and HNE-GS to be the best natural substrates of aldose reductase known so far and exposing a new efficient detoxification route of HNE.

Aldehyde Reductase↗
PubMed1995

Gene-targeted inhibition of transactivation of human immunodeficiency virus type-1 (HIV-1)-LTR by antisense oligonucleotides.

We have used an in vitro approach to study the efficiency of antisense oligonucleotides in inhibiting LTR-(HIV-1)-directed CAT expression catalyzed by tat protein, the functional protein of the transactivator gene. We selected the target sequence localized near the 5' end of the tat mRNA. The following conclusions can be drawn from the data presented here: a) Antisense oligonucleotides modified by conjugation of cholesterol at the 3' end have a severalfold higher inhibitory response, b) inhibitory response is dependent on the mode of introducing oligonucleotides, and c) the inhibition by antisense oligonucleotides is sequence specific and directed towards the targeted region. This approach could be useful for targeting functional regions of regulatory gene products and designing gene-targeted inhibitors of virus replication.

Animals↗
PubMed1995

Supercritical carbon dioxide extraction and quantification of bioactive neolignans from Magnolia virginiana flowers.

Magnolia virginiana L. flowers were extracted sequentially with supercritical CO2, supercritical CO2 modified with 5% chloroform, and supercritical CO2 modified with 5% methanol at 40 degrees C and 400 atm. The biologically active neolignans 3,5'-diallyl-2',4-dihydroxybiphenyl (1), 4,4'-diallyl-2,3'-dihydroxybiphenyl ether (2), 5,5'-diallyl-2,2'-dihydroxybiphenyl (3), and 3,5'-diallyl-2'-hydroxy-4-methoxybiphenyl (4) present in these extracts, were quantified by HPLC using photodiode array detection. Compounds 1-4 present in one gram dried flowers were found to be 0.11, 1.16, 1.66, and 0.42%, respectively. This is the first report of the supercritical extraction and quantification of bioactive neolignans from Magnolia virginiana L. flowers.

Carbon Dioxide↗
PubMed1995

Effect of tracheal gas insufflation on gas exchange in canine oleic acid-induced lung injury.

OBJECTIVE: To determine the effect of tracheal gas insufflation on gas exchange in oleic acid-induced lung injury in dogs. DESIGN: Prospective, longitudinal study. SETTING: University research laboratory. SUBJECTS: Five mongrel dogs. INTERVENTIONS: The dogs were anesthetized, paralyzed, and mechanically ventilated. Lung injury was induced by infusing 0.09 mL/kg of oleic acid and pulmonary artery occlusion (wedge) pressure (PAOP) was increased to 15 mm Hg by infusing fluids to enhance pulmonary edema formation. After 60 mins, PAOP was allowed to decrease to 5 mm Hg and was maintained at 5 mm Hg for 60 mins to stabilize the pulmonary edema. We studied the effect of tracheal gas insufflation on gas exchange at low and high end-expiratory lung volumes achieved by a positive end-expiratory pressure of 5 and 12 cm H2O, respectively. The FIO2 values of the ventilator and catheter were equivalent (0.6). Each tracheal gas insufflation stage at low and high end-expiratory lung volume was preceded and followed by conventional mechanical ventilation stages without tracheal gas insufflation. During transitions between conventional mechanical ventilation and tracheal gas insufflation, end-expiratory lung volume was maintained constant by adjusting positive end-expiratory pressure while monitoring esophageal pressure and inductive plethysmography. Tidal volume was maintained constant throughout the protocol (0.40 L). MEASUREMENTS AND MAIN RESULTS. At end stage, we measured PaCO2, PaO2, total physiologic deadspace fraction, and venous admixture, which were 43 +/- 4 torr (5.7 +/- 0.5 kPa), 325 +/- 6 torr (43.3 +/- 0.8 kPa), 53 +/- 3%, and 4.0 +/- 0.3% before oleic acid lung injury, respectively. After oleic acid injury at low end-expiratory lung volume, these variables were 55 +/- 4 torr (7.3 +/- 0.5 kPa), 73 +/- 13 torr (9.7 +/- 1.7 kPa), 61 +/- 4%, and 50 +/- 7%, respectively. During tracheal gas insufflation at low end-expiratory lung volume conditions, PaCO2 and the total physiologic deadspace fraction decreased significantly (p < .05) to 45 +/- 4 torr (6.0 +/- 0.5 kPa) and 50 +/- 5%, respectively. Under high end-expiratory lung volume conditions, PaCO2 and the total physiologic deadspace fraction were 55 +/- 7 torr (7.3 +/- 0.9 kPa) and 61 +/- 6%, respectively; during tracheal gas insufflation, these variables decreased to 43 +/- 4 torr (5.7 +/- 0.5 kPa) and 52 +/- 5%, respectively (p < .05). Increasing end-expiratory lung volume improved both PaO2 and venous admixture (p < .05) but tracheal gas insufflation had no significant effect on oxygenation efficiency when end-expiratory lung volume was held constant. CONCLUSIONS: Tracheal gas insufflation augmented alveolar ventilation effectively in the setting of oleic acid-induced lung injury in dogs. When end-expiratory lung volume and tidal volume were kept constant, tracheal gas insufflation did not affect oxygenation.

Animals↗
PubMed1995

Health aspects of pregnancy and childbirth: United States, 1982-88.

Statistics collected in 1988 are presented on the timing of the first prenatal visit, the source of prenatal care, smoking and alcohol use during pregnancy, low birthweight, and how delivery was paid for. The data are shown by race and characteristics of the mother and the pregnancy. Trends between 1982 and 1988 are also presented.

Adult↗
PubMed1995

The value of a postoperative radiation therapy in FIGO stage I and II endometrial cancers.

PURPOSE: The incidence of endometrial cancer has increased considerably within the last decades. Due to early symptoms more than 88% of all patients present initially with FIGO stage I or II disease. PATIENTS AND METHODS: One hundred and forty-four patients out of 192 patients with stage I endometrial cancers received surgical treatment alone. Like the remaining 48 patients 39 out of 65 patients with stage II tumors received adjuvant radiation therapy with 50 Gy to the true pelvis. RESULTS: Independent on the chosen treatment results in stage I were influenced by the depth of myometrial invasion (p = 0.023). With a crude 5-year survival rate of 88% patients with less than 33% reached life expectation of matched healthy women. With deeper infiltration crude survival rates were as low as 77%. In stage II tumors 5-year crude survival was elevated 60 to 80% independent on the depth of myometrial infiltration by adjuvant radiation therapy (p = 0.11). CONCLUSIONS: Despite its potential curability and the general knowledge that the prognosis of endometrial carcinomas is governed by a number of factors there are no generally accepted standard treatment modalities available Thus there is great demand for randomized clinical trials.

Adult↗