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Biomedical subjects

J Harper

Publications and source records attributed to J Harper.

At least 127 records · Page 7Linked to original sources
PubMed1987

Iron-transferrin-induced increase in protein kinase C activity in CCRF-CEM cells.

Iron transferrin has been found to induce a mean 10-fold increase in the activity of protein kinase C in CCRF-CEM cells. This increase was not detectable up to 45 min after treatment of cells with iron transferrin, although after 60 min, a maximal increase in enzyme activity was observed. Similarly, iron transferrin at concentrations of 0.1-0.5 microgram/ml did not alter protein kinase C activity, while concentrations of iron transferrin of 1-100 micrograms/ml induced a maximal increase in enzyme activity. Apotransferrin and iron in the form of ferric citrate, as well as complexes of transferrin with copper, nickel, zinc, manganese, and cobalt did not increase protein kinase C activity. Additionally, CCRF-CEM cells pretreated with either actinomycin D or cycloheximide and then incubated with iron transferrin did not exhibit increased enzyme activity. Treatment with iron transferrin was found to have no effect on protein kinase C activity in normal human peripheral blood lymphocytes and in HL60, Daudi, and U937 cells. However, normal lymphocytes stimulated with phytohemagglutinin for 48 hr exhibited a 2-fold increase in protein kinase C activity following treatment with iron transferrin. These results indicate a specific effect of iron transferrin on protein kinase C activity in CCRF-CEM cells and in mitogen-stimulated human lymphocytes that may occur through increased synthesis of the enzyme.

Cell Line↗
PubMed1986

A behavioral role for enkephalins in regulating locomotor activity in the insect Leucophaea maderae: evidence for high affinity kappa-like opioid binding sites.

D'-Ala-2 met-5-enkephalinamide application to the cerebral ganglia of Leucophaea maderae results in a decrease in locomotor activity. The opiate antagonist, naloxone, can block this effect as well as the depressant effect of morphine on locomotor activity. D-Ala-2,leu-5-enkephalinamide and dynorphin enhance locomotor activity following their topical application to the cerebral ganglia. This effect also can be antagonized by concomitant naloxone treatment. Benzomorphans were the most potent ligands tested in their ability to displace [3H]D'-ala-2,met-5-enkephalinamide whereas mu and delta ligands were by comparison less potent. These results suggest the presence of kappa-like opioid receptors in Leucophaea cerebral ganglia. The kappa ligands also are potent in enhancing locomotor activity in addition to being weakly antagonized by naloxone. Again, these results indicate the presence of multiple-opiate receptor types in invertebrates.

Animals↗
PubMed1985

Inhibition of collagenase activity by extracts of bovine ocular tissues.

Bovine eyes were dissected and separate pools of lens, lens capsule, cornea and vitreous were extracted in guanidine, subjected to ultrafiltration, and examined for their effects on collagenolytic activity. Although lens extract was not inhibitory, the cornea and vitreous both contained inhibitors of collagenase. More inhibition was present in the filtrate of the vitreous than in the retentate, whereas the total amount of inhibition in the cornea was distributed almost equally between the two fractions. The inhibition observed was dose dependent. The partially purified inhibitors from cornea and vitreous blocked the activity of human skin and tadpole back skin collagenases, but they failed to inhibit the bacterial (Clostridium histolyticum) collagenase. The inhibitor was stable to heating to 60 degrees for 30 minutes and to trypsinization.

Animals↗
PubMed1984

A comparative trial of the Today contraceptive sponge and diaphragm.

A comparative trial was conducted in the United States to compare the Today contraceptive sponge and the diaphragm used with spermicide. Subjects were randomly assigned to contraceptive methods and were followed up for 1 year. None of the subjects were previous sponge users, but about 30% were previous diaphragm users. The overall cumulative 1-year life-table pregnancy rate was higher for sponge users compared to diaphragm users. No serious side effects occurred with either product. The discontinuation rates for allergic-type reactions and discomfort were higher for sponge users. Similar rates of method-related complaints and discontinuation rates for personal and product-related reasons suggest there were no differences in the acceptability of the two products. In this trial, the allowable use time for the sponge was 2 days. The sponge is now recommended for 1-day use. The overall results of the study indicate the sponge to be a safe and acceptable method of contraception with an effectiveness rate in the range of that for other vaginal contraceptives.

Adolescent↗
PubMed1984

Avian-human reassortant influenza A viruses derived by mating avian and human influenza A viruses.

Reassortant influenza A viruses were produced by mating an avian virus (A/Mallard/NY/78, A/Mallard/Alberta/78, or A/Pintail/Alberta/79) with a wild-type human influenza A virus. From each mating a reassortant virus was obtained that contained the genes coding for the hemagglutinin and neuraminidase surface antigens of the human influenza A wild-type virus and the six other RNA segments ("internal genes") of the avian influenza A virus parent. The avian-human reassortant influenza viruses produced resembled their avian virus parent in that they produced plaques on MDCK monolayers at 42 C, a temperature restrictive for the human influenza viruses. In the trachea of squirrel monkeys, each avian-human reassortant influenza virus was as restricted in its replication as was its avian influenza virus parent. Thus, one or more of the six internal genes of each avian parent virus was responsible for restriction of the reassortant virus in monkeys. The A/Washington/80 X A/Mallard/NY/78 reassortant virus retained its phenotype of restricted replication in monkeys after five serial passages in vivo. It also failed to transmit to cagemates or induce resistance to wild-type virus challenge, and it did not initiate a systemic or enteric infection. These findings form the basis for evaluation of these attenuated avian-human reassortant influenza A viruses as live attenuated vaccines for humans.

Animals↗
PubMed1984

Characterization of Ross River viruses isolated from patients with polyarthritis in New Caledonia and Wallis and Futuna Islands.

Viruses isolated during 1979 and 1980 from patients with polyarthritis in New Caledonia and Wallis and Futuna Islands have been found to be more closely related to Ross River virus than any other regional Alphavirus. On the basis of virulence in suckling mice the majority of these isolates were found to be more closely related to the NB5092 strain of Ross River virus than to the prototype T48 strain.

Alphavirus↗
PubMed1983

Evaluation of the A/Seal/Mass/1/80 virus in squirrel monkeys.

An influenza A virus isolated from seals [A/Seal/Mass/1/80 (H7N7)] and an isolate of this virus obtained from a human conjunctiva were evaluated for replication and virulence in squirrel monkeys. When the seal virus was administered intratracheally, it replicated in lungs and nasopharynges and induced illness almost to the same extent that a human influenza A virus [A/Udorn/72 (H3N2)] did. In one monkey that died of pneumonia, the seal virus was recovered from spleen, liver, and muscle as well as lung. After conjunctival administration in monkeys, the seal virus replicated to a peak titer in the conjunctivae 30-fold greater than that attained by the human virus, but this difference was not statistically significant. In contrast, the seal virus replicated less well than the human virus in the tracheae and nasopharynges when administered by the conjunctival route. These results indicate that the seal virus can replicate efficiently in primates, that it can spread systemically, and that it might differ from human virus in being able to replicate slightly better in primate conjunctival tissue.

Animals↗
PubMed1983

Effectiveness of allopurinol against Leishmania braziliensis panamensis in Aotus trivirgatus.

Orally administered allopurinol at 50 mg/kg for 21 days showed pronounced antileishmanial activity against experimentally induced lesions of Leishmania braziliensis panamensis on the nose of Panamanian Aotus trivirgatus monkeys, with complete healing in 4 of 5, although parasitologic cure was achieved in only 2 of 5. The same total daily dose of drug, given in a divided dose twice daily, resulted in complete healing in all 5, and parasitologic cure in 4 of 5 animals. Standard treatment controls receiving 40 mg/kg of antimony stibogluconate intramuscularly for 15 days showed healing in 4 of 5 monkeys. It is not known if a similar level of effectiveness would result with this dose of allopurinol in humans, since Aotus may have a different pattern of metabolic conversion of the drug to the more active riboside.

Administration, Oral↗
PubMed1982

Isolation and characterization of an operator-constitutive mutation in the recA gene of E. coli K-12.

The recA gene of E. coli is regulated by a specific repressor, the lexA protein, which binds to an operator in the recA regulatory region. We describe in this paper the isolation and characterization of a mutant thought to carry an operator-constitutive mutation in the recA gene. This mutation has the following properties: 1) It partially suppresses the UV sensitivity of lexA- strains. 2) It maps near the recA gene. 3) It allows constitutive high-level synthesis of recA protein in both lexA- and lexA+ backgrounds. 4) It allows constitutive synthesis of the recA messenger RNA. 5) It is cis-acting. The mutation does not restore induced cellular mutagenesis in a lexA- background. The expression of induced repair and mutagenesis of UV irradiated phage lambda or the regulation of the lexA gene is not affected by the presence of the mutation in either a lexA+ or lexA- strain. These observations confirm other findings that high levels of recA protein synthesis per se is not sufficient for the expression of UV inducible functions and that the lexA protein represses other genes besides the recA gene.

Autoradiography↗
PubMed1982

Neonatal small left colon syndrome in twins.

There are no previous reports of small left colon syndrome in twins. Small left colon syndrome is reported in 2 sets of twins. In 1 set 1 twin had clinical and radiographic signs of small left colon syndrome. The sib was clinically normal and had no radiographic studies. In the other set, both twins had identical clinical and radiographic findings of hyperplastic left colon. This suggests a genetic and/or environmental intrauterine, rather than a postpartum etiology for the small left colon syndrome.

Barium Sulfate↗