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At least 271 records · Page 15Linked to original sources
PubMed1983

The effect of reserpine, syrosingopine, and guanethidine on the retention of discriminated escape reversal: peripherally administered catecholamines cannot reverse the reserpine amnesia in this situation.

In a series of experiments, the effects of reserpine, syrosingopine, and guanethidine on retention of a discriminated escape reversal training were investigated in mice. The peripherally and centrally acting reserpine produced amnesia while the primarily peripherally acting compounds, syrosingopine or guanethidine, did not produce amnesia even when given in high dosages or when training was given with low footshock. Unlike in the passive avoidance situation, peripherally administered norepinephrine or dopamine was not able to attenuate the reserpine-induced amnesia. The results were discussed in terms of the role of biogenic amines in memory formation.

Animals↗
PubMed1998

A colorimetric reverse transcriptase assay optimized for Moloney murine leukemia virus, and its use for characterization of reverse transcriptases of unknown identity.

A non-radioactive reverse transcriptase (RT) assay, reported as useful for lentivirus RTs, was optimized for the measurement of Moloney murine leukemia virus (MMuLV) RT. The optimized assay could detect 0.3 microU of MMuLV RT. The specificities of the MMuLV and lenti RT assays were demonstrated using the RTs of human immunodeficiency virus type 1, simian immunodeficiency virus, feline immunodeficiency virus (FIV), visna virus, human T-cell lymphotropic virus type 1, MMuLV and feline leukemia virus (FeLV). An RT activity blocking antibody (RTb-ab) assay was standardized for Mn2+ dependent MuLV-related RTs. The assay was used to demonstrate the distinct antigenic properties of RTs from mammalian MuLV-related retroviruses and lentiviruses. Cross-reactivity between MMuLV RTb-ab and FeLV RT but not between MMuLV RTb-ab and e.g. FIV RT was demonstrated. An RT activity found in the murine myeloma cell line SP2/0 was found to have similar assay preferences as MMuLV RT, and the MMuLV-RT hyperimmune sera reacted strongly against this RT, indicating the RT to be of MuLV-related etiology. The use of the RT and RTb-ab assays for detection and characterization of RTs of known or unknown identity is discussed.

3T3 Cells↗
PubMed2002

Heparin reversal in off-pump coronary artery bypass surgery: complete, partial, or no reversal?

Several clinical studies have reported that avoiding cardiopulmonary bypass reduces postoperative bleeding. The purpose of this study is to verify that protamine during off-pump coronary artery bypass surgery produces significant reduction of postoperative bleeding. Sixty consecutive patients undergoing off-pump coronary artery bypass surgery were prospectively randomized in three groups: Group A received 1 mg of protamine every 100 IU of heparin, Group B 0.5 mg of protamine every 100 IU of heparin, and Group C none. The three groups were analyzed for differences in preoperative cardiac function, pre-, intra-, and postoperative coagulation profile, intraoperative variables, and postoperative bleeding. In the three study groups, no statistically significant difference was found in preoperative cardiac function, pre- and intraoperative coagulation profile, and prothrombin time, activated partial thromboplastin time, platelet count in the first postoperative day. In Group A, total postoperative bleeding, use of packed red blood cells, and mild pericardial effusion prevalence at discharge were significantly lower only when compared to Group C, but they were not significantly different when compared to Group B. In off-pump coronary artery bypass surgery, heparin should be reverted with protamine, otherwise the postoperative bleeding risk might increase. Partial heparin reversal might not increase postoperative bleeding risk, but it may reduce dose-dependent protamine adverse effects.

Aged↗
PubMed2005

Optimal check size and reversal rate to elicit pattern-reversal MEG responses.

OBJECTIVE: To determine the impact of check size and interstimulus interval (ISI) on neuromagnetic visual cortical responses. METHODS: We recorded visual evoked fields to pattern-reversal stimulation with central occlusion in ten subjects. The -100 ms magnetic activation (P100m) was analyzed by single dipole modeling. RESULTS: With 1 s ISI, P100m strengths increased as check size increased from 15' up to 120' of visual arc, and larger checks elicited less P100m activation. With 120' checks, we found no P100m attenuation as ISI decreased from 4 s to 0.16 s. P100m sources around the calcarine sulcus did not vary with check size or ISI. CONCLUSIONS: The magnitude of cortical activation during visual contrast processing is check size-dependent and the 120' checks are optimum for future studies on neuromagnetic visual cortical functions using central-occluded stimulation. The corresponding neuronal activation demonstrated a short refractory period less than 0.16 s. We also found significantly overlapping cortical representation areas for different check sizes or ISIs.

Adult↗
PubMed1975

Attribution theory, insomnia, and the reverse placebo effect: a reversal of Storms and Nisbett's findings.

Storms and Nisbett found that insomniacs got to sleep faster than usual on nights when they took placebos believed to be arousal pills. Our study attempted: (a) to replicate the reverse placebo effect using a method of measurement considered more accurate than the original technique, (b) to evaluate the effect of an arousal pill therapy after therapy is discontinued, and (c) to clarify which of two hypotheses better accounts for the effect. Using 42 insomniacs, the design varied whether pills were administered (pill) or withheld (no pill) and whether or not high justification was provided for taking the pills. The high-justification-pill and the high-justification-no-pill groups were given information intended to justify their participation, while the no-justification-pill and no-pill-no-justification groups were treated like the original arousal and control groups. Instead of a decrease in latency to sleep, the no-justification-pill group but not the high-justification-pill troup displayed a typical placebo reaction on nights they took the pills. Our results cast suspicion on the original finding. The lack of response by the high-justification-pill group is discussed in terms of Bem and Kelley's views of attribution theory.

Arousal↗
PubMed2001

Effect of up-regulating individual steps in the reverse cholesterol transport pathway on reverse cholesterol transport in normolipidemic mice.

Cholesterol acquired by extrahepatic tissues (from de novo synthesis or lipoproteins) is returned to the liver for excretion in a process called reverse cholesterol transport (RCT). We undertook studies to determine if RCT could be enhanced by up-regulating individual steps in the RCT pathway. Overexpression of 7alpha-hydroxylase, Scavenger receptor B1, lecithin:cholesterol acyltransferase (LCAT), or apoA-I in the liver did not stimulate cholesterol efflux from any extrahepatic tissue. In contrast, infusion of apoA-I.phospholipid complexes (rHDL) that resemble nascent HDL markedly stimulated cholesterol efflux from tissues into plasma. Cholesterol effluxed to rHDL was initially unesterified but by 24 h this cholesterol was largely esterified and had shifted to normal HDL (in mice lacking cholesteryl ester transfer protein) or to apoB containing lipoproteins (in cholesteryl ester transfer protein transgenic mice). Most of the cholesterol effluxed into plasma in response to rHDL came from the liver. However, an even greater proportion of effluxed cholesterol was cleared by the liver resulting in a transient increase in liver cholesterol concentrations. Fecal sterol excretion was not increased by rHDL. Thus, although rHDL stimulated cholesterol efflux from most tissues and increased net cholesterol movement from extrahepatic tissues to the liver, cholesterol flux through the entire RCT pathway was not increased.

Animals↗
PubMed2004

Technique and timing in women's and men's reverse one and one half somersault with two and one half twists (5335D) and men's reverse one and one half somersault with three and one half twists (5337D) 3 m springboard dives.

The purpose of this study was to compare timing and technique of males and females performing reverse twisting dives in elite international competition. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including takeoff and entry. Estimates of flight height and mass-normalised work done on the springboard were obtained from flight times. The data indicated that many males are able to complete an additional twist rotation because they attain more height, and therefore more time in the air, than females.

Diving↗
PubMed2025

A bacterial PrimPol-reverse transcriptase hybrid protein has a proofreading exonuclease activity that can be transferred to other reverse transcriptases.

Gene disruption analysis revealed that an E. coli PPRT protein, which has an N-terminal Primase-Polymerase (PrimPol) domain fused to a group II intron-like reverse transcriptase (RT) domain followed by a long C-terminal domain (CTD), contributes to a cellular oxidative DNA damage response in addition to its previously described function in phage defense. Biochemical analysis showed that the PrimPol domain has an error-prone DNA polymerase activity that enables read through of oxidation-induced DNA damage. Surprisingly, we found that the RT-like domain, in addition to synthesizing protein-primed DNAs for phage defense, has a 3' to 5' DNA exonuclease activity that functions in proofreading DNAs synthesized by the PrimPol domain. Extending these findings, we identified structural features that contribute to this proofreading activity, enabling us to associate it with both a group II intron-encoded and retroviral RT and suggesting general methods for incorporating proofreading activity into RTs.

DNA sequencing↗
PubMed1970

Reversal of the potassium entry mechanism in red cells, with and without reversal of the entire pump cycle.

1. (42)K has been used to study the ouabain-sensitive component of potassium efflux from intact human red cells.2. Ouabain-sensitive efflux of potassium was observed only in media containing either sodium ions in moderate or high concentration or potassium ions.3. The effects of sodium and potassium in the medium were not additive. Potassium ions always increased the ouabain-sensitive potassium efflux, but in media containing 4.2 mM-K an increase in sodium concentration from 4.5 to 131 mM had little effect.4. In potassium-free media, ouabain-sensitive potassium efflux increased roughly linearly as the external sodium concentration was increased from 35 to 155 mM.5. The sensitivity of potassium efflux to external potassium depended on the concentration of sodium in the medium. In a 5 mM-Na (choline) medium, ouabain-sensitive potassium efflux was half-maximal at about 0.27 mM-K. In a 150 mM-Na medium the effect of potassium was half-maximal at about 1 mM-K. The relation between external potassium concentration and ouabain-sensitive sodium efflux was similarly influenced by the concentration of sodium ions in the medium.6. Inosine greatly reduced the ouabain-sensitive efflux of potassium into both 5 mM-K and potassium-free media. It probably acted by reducing the intracellular phosphate concentration to a low level.7. Ouabain-sensitive potassium efflux was not affected by the concentration of inorganic phosphate outside the cells and was not associated with a ouabain-sensitive efflux of phosphate of comparable magnitude. A small associated efflux could not be excluded.8. Simultaneous measurements of sodium efflux and of potassium efflux from identical batches of cells incubated in potassium-free media showed that inosine reduced ouabain-sensitive potassium efflux at the same time as it increased ouabain-sensitive sodium efflux.9. When cells that had been largely depleted of energy stores by pre-incubation with 2-deoxyglucose were incubated in high-sodium media, with and without potassium, it was observed that potassium in the medium increased the ouabain-sensitive potassium efflux but reduced the ouabain-sensitive efflux of sodium.10. Simultaneous measurements of the ouabain-sensitive efflux of potassium and influx and efflux of sodium across the membranes of starved cells incubated in potassium-free media, with and without inosine, suggested that ouabain-sensitive potassium efflux was associated with a net ouabain-sensitive entry of sodium.11. The results are best explained by supposing that the ouabain-sensitive efflux of potassium does not reflect lack of discrimination by the mechanism responsible for sodium expulsion, but is brought about by the reversal of steps in the pump cycle normally responsible for potassium entry.

Biological Transport, Active↗
PubMed1978

Reverse transcriptase of RNA tumor viruses. V. In vitro proteolysis of reverse transcriptase from avian myeloblastosis virus and isolation of a polypeptide manifesting only RNase H activity.

Purified avian myeloblastosis virus reverse transcriptase contains two subunits that are structurally related. The large subunit, beta (molecular weight, 95,000), was converted in vitro by chymotrypsin into a polypeptide of molecular weight 63,000. This polypeptide was indistinguishable from the small subunit, alpha (molecular weight, 65,000), in its chromatographic behavior on the phosphocellulose column and its tryptic peptide composition. During this proteolytic conversion, a polypeptide of molecular weight 32,000 (fragment B) was obtained. It was composed of tryptic peptides unique to beta and appeared to be derived from the portion of the beta subunit that was cleaved off during the conversion of beta into alpha. Upon continued proteolysis, a smaller polypeptide of molecular weight 24,000 (fragment A) was generated. This polypeptide manifested only RNase H activity and shared common amino acid sequences with beta and alpha subunits. Fragment A did not share any amino acid sequence homology with fragment B.

Avian Leukosis Virus↗
PubMed1983

Enzymatic reversibility of nonenzymatic glycosylation of the glomerular basement membrane. Is the diabetic glomerulopathy principally reversible?

Recent investigations point to the nonenzymatic glycosylation as a cause of long-term complications in diabetes mellitus. We describe an enzymatic activity that cleaves glucose from the glomerular basement membrane (GBM), present in lysosomal preparations of diabetic lymphocytes. The GBM, nonenzymatically glycosylated or obtained from rats with diabetes, were incubated with enzyme preparations, separated on Sephadex G-25 and applied for glucose measurement on gas chromatography and mass spectroscopy. The lysosomal preparation of diabetic lymphocytes cleaved from rat GBM, which were nonenzymatically glycosylated 300-500 ng glucose/mg GBM protein, from diabetic rat GBM 300 ng glucose/mg GBM protein. A lysosomal preparation of normal lymphocytes failed to do so, indicating enzyme induction in the diabetic state. Control studies with the glycosylated hemoglobin AIc confirmed this finding and showed the specificity of the enzyme, as alpha-glucosidase and beta-glucosidase failed to cleave the N-glycosidic bond between glucose and the protein. The enzymatic activity can be described formally as a N-l-deoxyfructofuranosyl-glucohydrolase, which could be responsible for a potential reversibility of diabetic GBM changes.

Animals↗
PubMed2002

Two cases of malignant hypertension with reversible diffuse leukoencephalopathy exhibiting a reversible nocturnal blood pressure "riser" pattern.

We report two cases of malignant hypertension with reversible diffuse leukoencephalopathy demonstrating a nocturnal blood pressure (BP) rising pattern ("riser" pattern). Case 1 was a 54-year-old man diagnosed with malignant hypertension who presented with diffuse leukoencephalopathy and nocturnal BP rise during the acute phase. These abnormal findings diminished after treatment of hypertension. Case 2 was a 50-year-old woman diagnosed with malignant hypertension in association with leukoencephalopathy, heart failure and acute renal failure. She also presented with a "riser" pattern during the acute phase. In contrast to case 1, the leukoencephalopathy and "riser" pattern in case 2 were not improved even after 1 month of treatment. Following intensive antihypertensive treatment, renal failure was improved in case 1, but renal failure was not improved after 1 month in case 2. In conclusion, a possible explanation of this phenomenon is that a causative volume overload due to renal dysfunction produced the temporal leukoencephalopathy-like brain edema and "riser" pattern in these cases.

Blood Pressure↗
PubMedDate not supplied

Sex reversal in a child with duplication of sex reversing locus on the short arm of the X chromosome (Xp).

We report a child with a female phenotype possessing a karyotype of 46,XY,13p+. The child had female external genitalia, and manifested severe mental retardation, pulmonary atresia and multiple congenital abnormalities. Laparoscopy revealed the presence of streak gonads and Müllerian structures. Histological examination of the gonads showed ovarian-like stroma with immature seminiferous tubules. Chromosome and gene analyses demonstrated Xp11.23 (or 11.3)-pter duplication and an intact sex determinating factor of Y (SRY). The findings of this case suggest that duplication of Xp causes sex reversal in the presence of SRY.

DNA-Binding Proteins↗
PubMed2005

Forward in reverse: how reverse genetics complements chemical genetics.

Pharmaceutical discovery has a renewed interest in physiological screening, while chemical genomics initiatives will soon provide a large amount of cellular assay data. However, there is no single robust approach to connect active compounds with their targets, limiting their experimental and therapeutic use. Systematic matching of chemical genetic phenotypes with reverse genetic phenotypes would provide a valuable starting point for many investigations.

Animals↗
PubMed1992

Pattern reversal visual evoked potentials (PVEPs) in transient ischemic attacks (TIAs) and prolonged reversible ischemic neurological deficits (PRINDs) of anterior circulation with normal EEGs and normal cranial CTs.

Out of 75 patients with TIA or PRIND we selected 9 TIAs and 6 PRINDs with normal EEGs and CCTs, full recovery of neurological function, no history of amaurosis fugax and no findings of visual impairments. PVEPs were derived from 01-02 to Fz and Cz as ground following binocular pattern reversal visual stimuli of 1.9 Hz. Interhemispheric differences of the latencies of P60, N80, P100 and of the amplitudes N80/P100 and P100/N140 were compared with the corresponding parameters of 22 age matched controls. In contrary to the latency differences the interhemispheric difference of the amplitude N80/P100 was highly significantly larger (33.5 +/- 16.0%) in patients than in the control group (12.8 +/- 9.8%) (p < or = .0005). The amplitude P100/N140 behaved the same way (p < or = .025); the amplitude of the affected side being smaller. There were no statistical differences between TIAs and PRINDs and a tendency was seen for normalization of the differences with increasing time distances between the onset of the ischemic attack and the point of time of the recordings.

Adult↗
PubMed1990

Some yeast proteins are recognized by antibodies to reverse transcriptases from several mammalian retroviruses and display reverse transcriptase activity.

Antibodies directed against reverse transcriptases (RT) of the mammalian retroviruses SSV and RD114 recognize specifically on Western Blots yeast cytoplasmic soluble proteins of 31 and 45 kDa respectively and inhibit RT activity in this fraction. Anti RLV RTIgG recognizes a protein of 40-43 kDa in the particulate (VLP) fraction and inhibits RT activity in it. No inhibition of RT activity was seen with normal serum anti AMV RTIgG or antisera against yeast DNA polymerase I and DNA polymerase III. These yeast RTs display RNase H activity and are not inhibited by aphidicolin. They prefer Mn+2 as cofactor over Mg+2, display an optimum temperature of 25-30 degrees C and are expressed in a diploid as well as 2 haploid strains and are thus distinct from yeast Ty encoded RTs.

Antibody Specificity↗
PubMed1989

A novel in situ colony screening method to detect human immunodeficiency virus reverse transcriptase activity expressed in bacteria. Isolation of pseudorevertants of reverse transcriptase mutants.

An in situ screening procedure is described that permits the detection of RNA-dependent DNA polymerase activity in bacterial colonies expressing the reverse transcriptase of the human immunodeficiency virus. The procedure has been applied to the isolation of rare pseudorevertants of an inactive parental mutant.

Amino Acid Sequence↗
PubMed1985

Arteriovenous flow reversal, experimental investigations. I. Complete flow reversal of the small intestine and of the rear extremity of the dog.

Segments of the small intestine and hind extremities of dogs were perfused under the condition of complete arterio-venous flow reversal (AVFR). In the intestinal segments, the peripheral resistance under AVFR conditions was 4.4 times higher than under orthograde perfusion. Petechiae and hemorhagic infarction were observed. The average flow resistance of the hind extremities was 2.4 times higher than the resistance in control extremities. The pO2 and the O2 saturation in the blood, outflowing from the AVFR extremity was lower than in the control extremity, however, the pO2 was higher. The oxygen consumption was somewhat lower than in the control extremity. It is concluded that by complete AVFR an extremity may be supplied sufficiently with oxygen at least temporarily.

Animals↗