Coherence and decay of Rydberg wave Packets.
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Journal Article↗
Biomedical subjects
J Parker
Publications and source records attributed to J Parker.
Mistranslation during phenylalanine starvation.
Starvation for phenylalanine led to leucine misincorporation frequencies of 0.1 and 0.6 at UUC codons in the argI transcript of Escherichia coli, but no detectable misincorporation at a UUU codon. Under similar starvation conditions the relative synthesis of full sized MS2 coat protein, encoded by the RNA virus or a DNA copy, is greatly reduced, preventing analysis of the protein. This reduction in amount is unaffected by a rpsL mutation.
Base Sequence↗
Strains overproducing tRNA for histidine.
Hybridization analysis of total genomic DNA indicated that Escherichia coli K12 contains a single copy of the gene encoding the histidine-accepting tRNA. This gene was subcloned onto an inducible expression vector under the control of the tac promoter. Strains carrying the resulting plasmid showed five- to six-fold increased histidine-accepting activity after induction. This overproduction of tRNAHis did not effect the growth rate of the strain or lead to derepression of the histidine biosynthetic enzymes. Neither did it have an effect on mistranslation elicited by histidine starvation. However, in cells starved for histidine by the addition of alpha-methyl histidine, the overproduction of tRNAHis interfered with the ability of the cells to recover from starvation.
Base Sequence↗
Polymorphonuclear leucocyte function in rheumatoid arthritis.
Controversy exists over the function of polymorphonuclear leucocytes (PMN) in rheumatoid arthritis (RA). We found no difference in the phagocytic and migratory ability of PMN from 45 patients with RA, when compared with PMN from 19 RA patients who had a history of recurrent infection, and 40 normal healthy age- and sex-matched controls. We conclude that the increased incidence of bacterial infection reported in RA is not the consequence of an intrinsic defect in PMN function.
Aged↗
Custom-made vaginal balloons for strengthening circumvaginal musculature.
A technique for making individualized silicone rubber intravaginal balloons is described. The method entails investing alginate vaginal impressions in silicone rubber and casting a resin model which is then dipped repeatedly in a Silastic Dispersion (Dow Corning, Q7-2213). The range of forces developed by circumvaginal muscles during maximum contractions was determined to be 0.5-4 lbs. Pressure-volume relationships of the balloons showed that the pressure of filling fluid was an accurate replica of the mean pressure in the vagina.
Female↗
Suramin antiviral therapy in the acquired immunodeficiency syndrome. Clinical, immunological, and virologic results.
The human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) requires reverse transcriptase for viral replication. We treated 12 patients who had acquired immunodeficiency syndrome and active HTLV-III/LAV viremia with suramin, a potent competitive inhibitor of reverse transcriptase, in six weekly induction doses of 1 g, followed by weekly maintenance doses of 500 mg. Three of eleven evaluable patients had complete inhibition of viral reverse transcriptase levels, lasting at least 18 weeks in each. Two additional patients had marked reduction in reverse transcriptase activity. Nadir serum suramin levels at the end of the induction phase correlated with the level of reverse transcriptase reduction. Toxicity included hepatic transaminase elevation, fever, malaise, rash, proteinuria, paresthesias, reversible neutropenia, and adrenal insufficiency. Objective clinical improvement was documented in 1 patient, but no patient had improvement in immune function and 7 patients had recurrent opportunistic infections. Although suramin may suppress HTLV-III/LAV viremia, its significant toxicity and lack of effect on immune variables indicate that alternative therapy will be required.
Acquired Immunodeficiency Syndrome↗
Administration of ribavirin to neonatal and pediatric patients during mechanical ventilation.
We have modified the circuits of pressure-preset and volume-preset ventilators to permit the administration of ribavirin to mechanically ventilated infants suffering from respiratory syncytial virus. The modifications isolate the ventilator itself and permit continuous aerosolization for as long as seven days without ventilator malfunction from the effects of crystallized medication. Excessive spilling of ribavirin into the environment is also avoided. Each institution must devise its own experimental protocols and gain permission from its own committee on human experimentation and from the parent/guardian of the patient before administering such treatment.
California↗
Detection of neural tube defects with alpha-fetoprotein measurement in amniotic fluid. A protocol for managing elevated values.
The clinical efficacy of rocket immunoelectrophoresis (RIE) and radioimmunoassay (RIA) methods for the measurement of amniotic fluid alpha-fetoprotein (AFP) were compared in separate series of over 1,000 pregnancies each. Using a mean +3 SD limit, 21 of 1,414 pregnancies monitored with RIE and 21 of 1,006 monitored with RIA were interpreted as having borderline elevated values. Five of the elevated AFP values in each series represented abnormal fetuses. No neural tube defects went undetected, although one was recognized only with ultrasound. Only two of seven abnormal fetuses had a family history of neural tube defects, indicating that maternal serum AFP measurement is an important preventive measure in pregnancies that are not recognized as at high risk. The data support the use of commercially available RIA kits for amniotic fluid AFP measurement and suggest a protocol for management of elevated values.
Amniotic Fluid↗
Juvenile nasopharyngeal angiofibroma.
JNA is a highly vascular, benign, yet locally invasive tumor that occurs in preadolescent males. Diagnosis is based on history, physical examination, and radiographic findings. CT scanning is invaluable for evaluating tumor extent. Angiography combined with embolization aids surgeons in identifying the main feeding vessels and decreasing intraoperative blood loss. Surgery is the mainstay of therapy with radiation therapy reserved for inoperable masses. For highly aggressive, recurrent angiofibroma, chemotherapy has shown some promise.
Adolescent↗
The ethics of health care.
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Ethics, Medical↗
Sensitivity to alpha/beta-interferon is independent of N-linked complex-type oligosaccharides on cell-surface-membrane glycoproteins.
The extent of involvement of carbohydrate structures in the mechanism of action of alpha and beta-interferon (IFN-alpha, IFN-beta) is undefined. In this report we examine the role of complex-type N-linked oligosaccharides in the response to these interferons. The response of mouse leukemia L 1210S cells, grown in the presence of swainsonine, an inhibitor of Golgi mannosidase II [Tulsiani, D. R. P., Harris, T. M. and Touster, O. (1982) J. Biol. Chem. 257, 7936-7939; Elbein A. D., Solf, R., Dorling, P. R. and Vosbeck, K. (1981) Proc. Natl Acad. Sci. USA 78, 7393-7397], to mouse IFN-alpha/beta, both with respect to antiviral and antigrowth effects, remains intact in spite of the total absence of complex-type N-linked oligosaccharides. Also, there is no difference in the response to human IFN-beta of a parental Chinese hamster ovary cell line and a mutant lacking beta-N-acetylglucosaminyltransferase I and therefore unable to synthesize complex-type N-linked oligosaccharides [Stanley, P., Callibot, V. and Siminovitch, L. (1975) Cell 6, 121-128]. These results are significant in permitting the conclusion that the carbohydrate-specific binding of IFN-alpha and IFN-beta to gangliosides cannot be due to a similarity of the ganglioside carbohydrate to that of a glycoprotein containing a complex-type N-liked oligosaccharide.
Alkaloids↗
Primary structure of histidine-tRNA synthetase and characterization of hisS transcripts.
Histidine-tRNA synthetase is one of the smallest bacterial aminoacyl-tRNA synthetases. It is less than one-half the size of the largest aminoacyl-tRNA synthetases. The entire nucleotide sequence of the Escherichia coli hisS locus was determined. The coding region is comprised of 424 codons, and the sequence was determined for 200 nucleotides on the 5'- and 3'-sides of the coding region. The translated nucleotide sequence was confirmed extensively by independent amino acid sequence information obtained by Edman degradations of purified peptides and by measurements of peptide masses by fast atom bombardment mass spectrometry. A significant sequence alignment of four bacterial aminoacyl-tRNA synthetases was reported recently (Webster, T., Tsai, H., Kula, M., Mackie, G., and Schimmel, P. (1984) Science 226, 1315-1317). Although the four enzymes vary considerably in length, this match occurs within the first 100 amino acids of each of the four enzymes and is in the segment believed to be part of the catalytic core. But no strong alignment could be found of the histidine sequence with these four tRNA synthetase sequences. This enzyme may be derived, therefore, from a different progenitor. Previous work suggested that three places in the hisS 5'-noncoding sequence could be promoter sites for RNA polymerase (Eisenbeis, S. J., and Parker, J. (1982) Gene 18, 107-114). We detected a 1400-nucleotide RNA species by RNA blot analysis with a hisS-specific probe. S1 nuclease mapping demonstrated a 5'-end to the RNA species occurs at -67 +/- 1, relative to the first nucleotide of the coding region. This position coincides with the predicted start site for transcription from one of the previously proposed promoter sites.
Amino Acid Sequence↗
Streptomycin-induced, third-position misreading of the genetic code.
Streptomycin was used to increase the frequency of errors in protein synthesis in vivo. In the system under study two misreading errors were observed. Both involved the erroneous insertion of lysine at asparagine codons, because of misreading of a pyrimidine as a purine at the 3' position of the codon. Streptomycin increased the errors at the two codons AAU and AAC to the same extent, thereby maintaining the error ratio found for basal level mistranslation.
Autoradiography↗
Effective patient education. A quasi-experiment comparing an individualized strategy with a routinized strategy.
A quasi-experiment was conducted on 127 hospitalized rheumatoid arthritis patients to determine the relative success of 3 patient teaching strategies--an individualized program, a routinized program, and a no-planned-instruction program--on patients' knowledge of their disease and treatment. Data analysis revealed that the individualized program produced a 100% greater learning gain than the routinized program in patients who had low pretest scores. The results suggest that maximum patient learning occurs when the teaching process accommodates important patient differences.
Arthritis, Rheumatoid↗
Comparison of serial diagnostic tests in a patient with invasive aspergillosis.
Studies on a liver transplant recipient with fatal disseminated aspergillosis are described. The concentration of IgG antibodies to Aspergillus rose sharply with the onset of fever and changes in the chest X-ray, reaching a peak on day 10. Thereafter, antibody concentrations fell and were within the normal range by day 21, when Aspergillus was first isolated from an endotracheal aspirate and one day before death. The fall in antibodies preceded a rise in circulating immune complexes but Aspergillus antigens were not detected in the serum. Serial quantitative assay for antibodies to Aspergillus may be more appropriate than culture or attempts to detect antigen in the early diagnosis of invasive aspergillosis in immunocompromised patients.
Antibodies, Fungal↗
Mioflazine, a potentially protective drug against ischaemic damage: a study in dogs.
The protective effect of intravenous mioflazine pretreatment was examined in intact dogs on cardiopulmonary bypass. The mechanical function of the left ventricle was measured by isovolumic pressure-volume relationships. Mioflazine alone had no inotropic effect. After one hour of normothermic (37 degrees C) global ischaemia of the whole heart, no control hearts, pretreated with solvent, recovered sufficiently to support the animal's circulation; this was not the case with animals pretreated with mioflazine, they all survived. After the 30-min reperfusion period, the solvent (control) pretreated hearts had a significantly lower (P = 0.05) systolic and higher (P = 0.001) diastolic pressure-volume curve than those given mioflazine.
Animals↗
IgG enzyme linked immunosorbent assay for diagnosis of invasive aspergillosis: retrospective study over 15 years of transplant recipients.
Four commercially available Aspergillus fumigatus antigens were compared in an IgG enzyme linked immunosorbent assay by testing multiple sera from 19 patients who had received renal and hepatic allografts and who had histologically confirmed invasive aspergillosis. Raised antibody levels were found in 16 of the 19 patients. More antibody responses were detected by culture filtrate antigens, but somatic antigens often detected antibodies sooner. When antibodies to Aspergillus antigens were present before transplantation the onset of fatal disseminated infection was earlier. Antibody levels often fell to within the normal range, even in cases of fulminant disseminated infection. Repeated serology was essential for detection of an antibody response.
Antibodies, Fungal↗
Spontaneous fractured neck of femur in rheumatoid arthritis: absence of radiographic changes on initial X-ray.
Spontaneous fractures have been documented in patients with osteoporosis and have been described in patients with rheumatoid arthritis. Two patients with rheumatoid arthritis who sustained femoral neck fractures in the absence of trauma are documented. Despite severe pain initial radiograph failed to demonstrate evidence of fracture, but subsequent radiographs later showed fractures in both cases. It is important in rheumatoid patients with continuing severe hip pain of sudden onset to suspect a stress fracture even if initial radiographs are normal.
Aged↗