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Biomedical subjects

J Strickler

Publications and source records attributed to J Strickler.

30 records · Page 2Linked to original sources
PubMed1988

Efficient expression of the yeast metallothionein gene in Escherichia coli.

The yeast metallothionein gene CUP1 was cloned into a bacterial expression system to achieve efficient, controlled expression of the stable, unprocessed protein product. The Escherichia coli-synthesized yeast metallothionein bound copper, cadmium, and zinc, indicating that the protein was functional. Furthermore, E. coli cells expressing CUP1 acquired a new, inducible ability to selectively sequester heavy metal ions from the growth medium.

Amino Acid Sequence↗
PubMed1988

Organization of the middle RNA segment of snowshoe hare Bunyavirus.

The genetic organization of the M RNA segment of snowshoe hare (SSH) virus, a member of the Bunyavirus genus of the family Bunyaviridae, has been determined. The middle (M) RNA segment has a single open reading frame (ORF) of 1441 amino acids. We have used amino- and carboxy-terminus sequencing and synthetic peptides to map proteins within the ORF. The order of the proteins translated from the single large open reading frame is G2, NSm, G1. The G2 protein extends from amino acids 14 to 299. The molecule is 286 residues long, with a computed nonglycosylated molecular weight of 31,973 Da. It is preceded by a cleaved 13 amino acid signal sequence. G2 includes a long highly hydrophobic sequence and contains three potential N-linked glycosylation sites. The G1 protein occupies the C-terminal end of the open reading frame from amino acids 474 to 1441 (968 amino acid residues) and has a computed nonglycosylated, molecular weight of 108,981 kDa. It has two potential N-linked glycosylation sites, and a potential transmembrane region followed by a potential cytoplasmic domain at the C-terminal end. If membrane associated it has an orientation of N-terminus outer, C-terminus inner. Limited trypsin digestion removes a 33-kDa fragment from the N-terminal end, leaving a virion-associated truncated G1 molecule (amino acids 762 to 1441) with a single N-linked glycosylation site. Between the G2 and G1 molecules there are 174 amino acids, sufficient to code for 19 kDa of protein. Some antibodies raised against peptides within this region react with proteins of 11 kDa (NSm) and 10 kDa present in infected cell lysates, but the exact relationship of these proteins to the open reading frame remains to be determined.

Amino Acid Sequence↗
PubMed1987

Characterization of the promoter, signal sequence, and amino terminus of a secreted beta-galactosidase from "Streptomyces lividans".

The gene for a secreted 130-kilodalton beta-galactosidase from "Streptomyces lividans" has been cloned, its promoter, signal sequence, and amino terminal region have been localized, and their nucleotide sequence has been determined. The signal sequence extends over 56 amino acids and shows the characteristic-features of signal sequences, including a hydrophilic amino terminus followed by a hydrophobic core near the signal cleavage site. The secretion of beta-galactosidase depends on the presence of the signal sequence. beta-Galactosidase is the major protein in culture supernatants and extracts of strains expressing the cloned beta-galactosidase gene and represents a valuable tool in the study of protein secretion in Streptomyces spp.

Base Sequence↗
PubMed1985

Molecular cloning of the complementary DNA for human tumor necrosis factor.

Tumor necrosis factor (TNF) is a soluble protein that causes damage to tumor cells but has no effect on normal cells. Human TNF was purified to apparent homogeneity as a 17.3-kilodalton protein from HL-60 leukemia cells and showed cytotoxic and cytostatic activities against various human tumor cell lines. The amino acid sequence was determined for the amino terminal end of the purified protein, and oligodeoxyribonucleotide probes were synthesized on the basis of this sequence. Complementary DNA (cDNA) encoding human TNF was cloned from induced HL-60 messenger RNA and was confirmed by hybrid-selection assay, direct expression in COS-7 cells, and nucleotide sequence analysis. The human TNF cDNA is 1585 base pairs in length and encodes a protein of 233 amino acids. The mature protein begins at residue 77, leaving a long leader sequence of 76 amino acids. Expression of high levels of human TNF in Escherichia coli was accomplished under control of the bacteriophage lambda PL promoter and gene N ribosome binding site.

Amino Acid Sequence↗
PubMed1981

Desmosome frequency: Experimental alteration may correlate with differential cell adhesion.

Differential cell adhesion, a suggested guiding force for tissue rearrangement during embryogenesis, could be affected by desmosome frequency. A model system for studying embryonic tissue-positioning behaviour involves combining different tissues and following their rearrangements. We have previously shown that for one tissue, embryonic chick heart ventricle, direction of tissue positioning can be altered experimentally. Heart tissue precultured for 2.5 days tends to segregate internally, while tissue pre-cultured for just half a day tends to segregate externally. Also, intact fragments of tissue tend to segregate internally, while reaggregates of trypsin-disaggregated tissues tend to segregate externally. We show here that treatments that increase the tendency to internalize also increase the frequency of adherens junctions and treatments that increase the tendency to externalize decrease the frequency of junctions. An identical hierarchical ordering of the 4 experimental tissues occurs with respect to positioning behaviour and desmosome frequency. In the hierarchy, 2.5-day-cultured fragments greater than 2.5-day-cultured reaggregates greater than 0.5-day-cultured fragments 0.5-day-cultured reaggregates, tissues to the left tend to segregate internally and to have more desmosomes. Tissues to the right segregate externally and have fewer desmosome. This is what is expected if desmosome are organelles for adhesion and if differential adhesion is a factor in tissue-positioning behaviour.

Analysis of Variance↗
PubMed1979

Legionnaires' disease in Kingport, Tennessee.

In August and September 1977 a discrete cluster of 27 serologically or pathologically confirmed cases of Legionnaires' disease, plus six highly presumptive cases were identified in the area of Kingsport, Tennessee. Three patients died. Most patients manifested severe pneumonia and fever; no mild or asymptomatic disease forms were recognized despite intensive case-finding efforts. Illness was epidemiologically associated with residing, visiting, or working in one geographic area of Kingsport, residence there being the factor most strongly associated. Although the attack rate for area residents was 0.64%, the randomly determined prevalence of serologic reactors was 5.2%, which is not significantly different from that in a nonimplicated control neighborhood. The epidemic did not correlate temporally with any identified environmental or demographic event. No source of the bacterium was found either by a detailed case-control study of area associations or by bacterial isolation from sentinel guinea pigs or environmental specimens. There was no evidence of person-to-person spread.

Disease Outbreaks↗
PubMedDate not supplied

Induction by E1A oncogene expression of cellular susceptibility to lysis by TNF.

Tumour necrosis factor alpha (ref. 1), synthesized primarily by monocytes in response to various invasive agents, induces a wide variety of biological effects relevant to regulating cell growth and differentiation, including the selective killing of some tumour cells and the growth stimulation of some normal fibroblasts. As tumour necrosis factor (TNF) appears to kill tumour cells preferentially, we asked whether TNF sensitivity correlates with the expression of specific oncogene(s). If so, by examining the cellular target(s) of the oncogene product, it might be possible to identify specific factor(s) which mediate TNF action. By using an in vitro cytotoxicity assay with NIH 3T3 and Fisher BRK-derived cells expressing exogenously introduced oncogenes, we found that adenovirus E1A proteins induce susceptibility to TNF killing.

Adenovirus Early Proteins↗
PubMedDate not supplied

Vertical and torsional correction in congenital superior oblique palsy by inferior oblique recession.

PURPOSE: Inferior oblique recession (Fink's technique) is one of various surgical procedures to manage congenital superior oblique muscle palsy. The authors aimed to determine the effectiveness of this operation in reducing vertical deviation and torsional deviation, and to assess the dose-effect relationship. METHODS: Fifty-eight patients presenting with unilateral congenital superior oblique palsy had an inferior oblique recession of 6 mm, 8 mm, or 10 mm (16, 35, and 7 patients, respectively). Vertical deviation and torsional deviation were measured before and after surgery by means of the dark red glass dissociation in front of Harms'tangent screen and the data were analyzed retrospectively. RESULTS: A cure rate of 88% was achieved, with no complications, and no overcorrections. For the 34 patients for whom long-term follow-up was possible (mean 2.8 years), final median postoperative vertical deviations and torsional deviations were 0.5 degrees and 0 degrees, respectively, both in primary position and in adduction upgaze. CONCLUSIONS: Inferior oblique weakening by recession proves to be an efficient and safe procedure for congenital superior oblique palsy, and its effect on vertical deviation can be predicted on the extent of recession. The operation can therefore be adapted to the patient, depending on the degree of the preoperative deviation.

Adolescent↗
PubMedDate not supplied

Comparative contraceptive efficacy of the female condom and other barrier methods.

Because the research design for the clinical trial establishing the contraceptive efficacy of the female condom--a six-month life-table probability of failure of 15% (12% in the United States vs. 22% in Latin America)--did not include randomization with another method of contraception, no definite conclusion about its comparative efficacy is possible. Comparisons using other female barrier methods as historical controls, however, provide evidence that, among women in the United States, the contraceptive efficacy of the female condom during typical use is not significantly different from that of the diaphragm, the sponge or the cervical cap. The six-month probability of failure during perfect use of the female condom is 2.6% among U.S. women, similar to rates for the diaphragm and the cervical cap but significantly lower than that for the sponge. Meaningful comparisons with the male condom are not possible because of the lack of data from carefully controlled prospective clinical trials. Extrapolations from the results on contraceptive efficacy suggest that perfect use of the female condom may reduce the annual risk of acquiring the human immunodeficiency virus by more than 90% among women who have intercourse twice weekly with an infected male.

Clinical Trials as Topic↗
PubMedDate not supplied

Contraceptive efficacy of the diaphragm, the sponge and the cervical cap.

A reanalysis of data from two clinical studies--in which 1,439 women were randomly assigned to use either the contraceptive sponge or the diaphragm and 1,394 women were randomly assigned to use either the cervical cap or the diaphragm--found first-year probabilities of failure during typical use of 17% for the sponge, 18% for the cervical cap and 13-17% for the diaphragm. The first-year probabilities of failure during perfect use are 11-12% for the sponge, 10-13% for the cervical cap and 4-8% for the diaphragm. The probability of failure during perfect use is significantly higher among women who have given birth than among those who have not for users of the sponge (19-21% vs. 9-10%) and users of the cervical cap (26-27% vs. 8-10%), but not for users of the diaphragm.

Contraceptive Devices, Female↗