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Biomedical subjects

K A Smith

Publications and source records attributed to K A Smith.

At least 127 records · Page 7Linked to original sources

The cumulative dose response effect of eicosapentaenoic and docosahexaenoic acid on blood pressure, plasma lipid profile and diet pattern in mild to moderate essential hypertensive black patients.

In this study eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were given in a cumulative manner, every 6 weeks, starting with 10 mg, then 100 mg, 1000 mg and 10,000 mg EPA daily to mild to moderate essential hypertensive black patients. The corresponding DHA doses were 3, 33, 333 and 3333 mg. A control group was given olive oil as placebo for the entire 24 weeks. The placebo group had lower diastolic and systolic blood pressures after 24 weeks than the EPA and DHA group. No effect was seen on plasma triglycerides, cholesterol, HDL-cholesterol and gamma-glutamyltranspeptidase at any stage of the trial. In the EPA group plasma free-EPA increased significantly from 1000 mg onwards and plasma free-arachidonic acid (AA) decreased after 1000 mg EPA. No other plasma free essential fatty acid changed during the trial, although the HDL:cholesterol increased slightly but non-significantly with an increase in EPA and DHA. No significant changes in diet pattern or body mass was observed. It is therefore concluded that EPA and DHA supplementation had no beneficial effects in mild to moderate essential hypertensive black patients except for a lowering of plasma AA.

Adult↗

Interleukin-2.

In the past year there have been significant advances in understanding the role of interleukin-2. Its role in the activation of T cells by antigen-presenting cells, the structure-activity relationships between interleukin-2 and its receptor and the subsequent signaling have all become clearer. The creation of mice with a specific defect in the interleukin-2 gene has given us a clearer idea of its role in vivo. Recent studies also suggest that interleukin-2 may finally find a role in immunotherapy.

Animals↗

Interferon alpha 2a and vindesine in the treatment of advanced malignant melanoma.

21 patients with advanced malignant melanoma were treated with interferon alpha 2a at 9MU daily with vindesine every 21 days. No patient had received previous chemotherapy. The overall response rate was 24% with a median survival time of 33 months in 18 patients. The four complete remissions were maintained for 20, 18, 15 and 11 months, while the single partial remission continues at 18 months after the start of treatment. Side-effects were generally mild or moderate and did not lead to cessation of therapy. This combination provides an active outpatient regimen for advanced melanoma and produces durable remissions.

Adult↗

Rational immunotherapy with interleukin 2.

Interleukin 2 (IL-2), a T lymphocyte product released upon antigen stimulation, has been used for cancer therapy in high doses for more than five years. More recently, its potential as a stimulant of cell-mediated immunity in infectious diseases, particularly those caused by intracellular microbes, has become appreciated. Drawing on the extensive information available as to the structure, cellular and molecular effects of IL-2, this review focuses on its use in patients with lepromatous leprosy and AIDS in low, physiologic doses. The data indicate that IL-2 is effective in stimulating cell-mediated immunity without systemic toxicity.

Humans↗

Molecular attenuation of vaccinia virus: mutant generation and animal characterization.

These studies demonstrated that the inbred BALB/c mouse strain can be optimized for the assessment of vaccinia virus virulence, growth, and spread from the site of inoculation and immune protection from a lethal vaccinia virus challenge. The studies established that manipulation of the vaccinia virus genome generated mutants exhibiting a wide range of attenuated phenotypes. The nine NYCBH vaccinia virus mutants had intracranial 50% lethal doses that ranged from 2 to greater than 7 log10 units. The decreased neurovirulence was due to decreased replication in brain tissue. Three mutants had a decreased ability to disseminate to the lungs, brains, livers, and spleens of mice after intranasal infection. One mutant had a decreased transmission from mice infected by tail scarification to naive cage mates. Although the mutants, with one exception, grew to wild-type titers in cell culture, they showed a growth potential on the scarified skin of mice that was dramatically different from that of the wild-type virus. Consequently, all of the mutants had significantly compromised immunogenicities at low virus immunization doses compared with that of the wild-type virus. Conversely, at high immunization doses most mutants could induce an immune response similar to that of the wild-type virus. Three Wyeth vaccine strain mutants were also studied. Whereas the thymidine kinase, ribonucleotide reductase, and hemagglutinin mutants had a reduced virulence (50% lethal dose), only the thymidine kinase mutant retained its immunogenicity.

Administration, Intranasal↗

The local side effects of transdermally absorbed nicotine.

Percutaneous nicotine administration induces predominant sudorific and rubiform responses in the skin which may be accompanied by subtle piloerection, hyperalgesia and pruritus (although these signs are not overtly manifest). These dermal responses are complex and mechanisms have been proposed for the direct nicotine-stimulation of sweat glands, piloerection and vasoconstriction. These reactions are accompanied by secondary activation and release of vasodilator peptides which produce a predominating vasodilator tone following topical administration, this response masking the direct axon reflex-mediated vasoconstriction.

Administration, Cutaneous↗

The systemic influence of recombinant interleukin 2 on the manifestations of lepromatous leprosy.

14 patients with lepromatous leprosy received twice daily injections of 10 micrograms recombinant interleukin 2 (rIL-2), by the intradermal route, in the skin of the back for 8 d (total dose, 160 micrograms). Lymphokine administration was accomplished without drug toxicity, or the development of acute nerve damage. The majority of patients developed nontender axillary lymphadenopathy during the course of treatment. Local injection sites showed progressively larger zones of induration, peaking at 24 h and persisting for many days. Early 12-h reactions were of a macular, erythematous nature and exhibited an increasingly striking diurnal variation. The morning injection sites were three- to fourfold larger in diameter than those placed in the evening (9 am to 9 pm). Systemic manifestations of intradermal rIL-2 administration were noted. Peripheral blood T cells, including CD4+ and CD8+ phenotypes, increased 2-2.5-fold and NK cells increased sixfold. Elevations in [3H]TdR incorporation into peripheral blood mononuclear cells occurred to a variety of mycobacterial antigens, but not to those of Mycobacterium leprae. Within 2 wk, biopsies at sites far removed from the back showed increased infiltration of mononuclear cells in 12 of 14 patients. Immunocytochemistry revealed the presence of newly emigrated CD4+ T cells, monocytes, and dermal CD1+ Langerhans cells. Endothelial cells of small dermal vessels expressed major histocompatibility complex class II determinants on their surface. Transmission electron microscopy of these specimens revealed markedly enlarged endothelial cells with many surface projections extending into the lumen as well as extravasating lymphoid cells. The numbers of acid-fast M. leprae in the peripheral sites were examined by slit smear and in biopsies of matched leprosy lesions taken before and after IL-2 administration. Within 2 mo, slit smears showed a 0.5 log or greater reduction in 12 of 14 patients, with a mean for all patients tested of 0.5 log units. Biopsy specimens showed a 1 log unit or greater reduction in the bacterial index (B.I.) in 6 of 14 patients. Historical controls in this Nepalese population showed a 0.5 log unit reduction after multidrug therapy over a period of 12 mo. Thus, after 8 d of IL-2 injections, a fivefold reduction in B.I. was observed during the first 2 mo of the study. Antibody levels against M. leprae phenolic glycolipid 1 (PGL-1) and lipoarabinomanan B were markedly elevated after IL-2 injections, while PGL-1 antigen levels were reduced. We conclude that the administration of rIL-2 has had a significant effect in decreasing the total body burden of M. leprae.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

Molecular cloning of a novel human cdc2/CDC28-like protein kinase.

A homology probing approach was utilized to isolate a new human protein kinase. Deoxyoligonucleotide probes recognizing a conserved subdomain in the COOH-terminal portion of protein kinases identified a cDNA clone encoding a putative kinase with predicted serine/threonine phosphorylation specificity. The full-length, 1.7-kilobase pair cDNA hybridizes to 1.7- and 3.4-kilobase mRNA transcripts in a number of tissues. The size of the encoded protein is 454 amino acids and consists of an NH2-terminal 130-residue segment, which may represent a regulatory region, followed by a 324-residue catalytic domain. Comparisons and alignments of the primary sequence and predicted secondary structure of the catalytic region to other known kinases reveal that the new kinase, denoted "CLK" (for CDC-like kinase), represents a prototype for a new family of human protein kinases bearing significant homology to the yeast cdc2/CDC28 kinases that regulate the cell cycle.

Amino Acid Sequence↗

Differentiation of T cell lymphokine gene expression: the in vitro acquisition of T cell memory.

A simple in vitro experimental system was devised to reflect the in vivo generation of a T cell anamnestic response so that T cell differentiation could be examined at the level of lymphokine gene expression. Comparison of neonatal and adult T cells revealed that both populations expressed the genes for interleukin 2 (IL-2) and its receptor, but only adult T cells were capable of transcribing mRNAs for IL-3, IL-4, IL-5, IL-6, interferon gamma, and granulocyte/macrophage colony-stimulating factor. However, neonatal T cells could be induced to undergo functional differentiation in vitro, thereby acquiring the capacity to express the lymphokine gene repertoire characteristic for adult T cells. These data suggest that the T cells generated from neonatal blood by a primary stimulation in vitro are functionally indistinguishable from the T cells in adult blood that presumably have undergone primary stimulation in vivo. Therefore, we propose that the term "memory cell" be applied to those T cells that can be identified by their differentiated state of inducible effector-lymphokine gene expression.

Adult↗

Conformational perturbation of interleukin-2: a strategy for the design of cytokine analogs.

Interleukin-2 (IL-2) is a representative of a growing family of small proteins termed lymphokines which are responsible for mediating cell differentiation, growth and function in the immune system. Many of these proteins are being evaluated for their clinical potential. From the perspective of drug development, structure-function analysis of these molecules and their receptors require the use methodologies different than those traditionally employed for small peptides and other natural products. However, similar pharmacologic principles apply and an understanding of ligand-receptor interactions and the associated responses is required in order to efficiently pursue agonist and antagonist design. Although IL-2 is a protein of only 133 amino acid residues for which a low resolution X-ray structure does exist, the complexity of its receptor system has provided an added challenge to structure-function studies. Consequently, little is known concerning the receptor contact residues for this protein. We have attempted to utilize established principles of protein and peptide structure to manipulate the conformation of IL-2 in a manner which has provided analogs helpful for receptor interaction studies. These proteins have not only providing useful information on the nature of the IL-2 receptor but have also revealed potential strategies for the design of IL-2 agonists and antagonists.

Amino Acid Sequence↗

Flavone acetic acid potentiates the induction of endothelial procoagulant activity by tumour necrosis factor.

Treatment of human umbilical vein endothelial cells with flavone acetic acid (FAA) at 800 micrograms/ml for 4 h resulted in a 3-11-fold increase in procoagulant activity. This increase was due to enhanced tissue factor expression on the endothelial cell surface, as evidenced by the blocking of the enhanced clotting with antibody to tissue factor, by substitution of normal with factor VII deficient plasma, or by simultaneous treatment of the endothelial cells with cycloheximide or actinomycin D. FAA was not toxic to endothelial cell at concentrations up to 1.6 mg/ml over 4 h. Combined treatment with FAA and tumour necrosis factor alpha (TNF-alpha) (100 pg/ml) produced a 675-fold (range 160-1980) increase in tissue factor activity, compared to 5-fold and 50-fold increases for the individual agents respectively. Northern blotting of total RNA from cells treated with the combination of agents or either agent alone, followed by probing with a cDNA to human tissue factor demonstrated a synergistic increase in tissue factor mRNA after combination treatment. In vivo, the combination of FAA and TNF-alpha could be shown to induce greater growth delay in two murine tumours than would be predicted on the basis of the activity of either agent alone.

Animals↗

113Cd nuclear magnetic resonance (NMR) study of the inhibitory effect of methylvinylether/maleic acid (PVM/MA) copolymer on the alkaline phosphatase of Escherichia coli.

The inhibitory effect of PVM/MA copolymer on the alkaline phosphatase (AP) of E. coli was investigated. Kinetic studies indicated that enzyme inhibition was characterized by a reduction in both the Vmax and the Km. Addition of 1 mM zinc or magnesium ions to the reaction prevented inhibition of the enzyme by the copolymer. The inhibitory effect of the copolymer on alkaline phosphatase was also investigated using 113Cd NMR after exchange of the active center metal ions with 113Cd. The resulting Cd(II)6AP exhibited characteristic 113Cd resonances reflecting the environment of the A, B, and C metal binding sites of the enzyme's active center. Addition of copolymer resulted in a 113Cd NMR spectrum which indicated removal of 113Cd from the C site and formation of two distinct forms of the enzyme. Possible explanations for the 113Cd NMR results are discussed.

Alkaline Phosphatase↗

Flow cytometric evaluation of hypoxic cells in solid experimental tumours using fluorescence immunodetection.

Numerous methods have been proposed for the detection of hypoxic cells using nitroimidazoles labelled with both radioactive and stable isotopes where the isotopic label becomes bound as a result of reductive metabolism of the nitro group. A new probe for hypoxia, 7-(4'-(2-nitroimidazol-l-yl)-butyl)-theophylline, is described where an immunologically recognisable hapten (theophylline) is covalently linked to a 2-nitroimidazole. Bioreduction of the nitroimidazole leads to binding of bioreductive metabolites, and hence the theophylline side-chain, to intracellular molecules. Immunochemical procedures are then used to stain cells containing the bound theophylline using an FITC-conjugated anti-serum. Flow cytometric analysis of stained cells is facilitated by co-staining cellular DNA, which allows discrimination of single cells in the sample and rejection of cell clumps and debris. The alternative use of an immunoperoxidase-conjugated anti-serum has been used to demonstrate the localisation of hypoxic cells in frozen tumour sections.

Animals↗

Anticoagulant treatment does not affect the action of flavone acetic acid in tumour-bearing mice.

Flavone acetic acid (FAA) is a novel antitumour agent that has a profound effect on the vasculature in murine tumour models. Previously we have shown that FAA induces a coagulopathy and thrombocytopaenia in tumour-bearing mice, and the purpose of the present study was to determine the significance of the FAA-induced intravascular coagulation in the antitumour action of FAA. Several anticoagulant agents were tested for their effectiveness in altering ex vivo coagulation of murine plasma; heparin and ancrod were found to be most effective. These agents were administered to tumour-bearing mice prior to FAA and TNF treatment with little effect on the induced regrowth delay. However: the FAA-induced consumption of platelets in tumour-bearing mice was not blocked by anticoagulant treatment. These data suggest that platelet consumption occurs independently of the normal coagulation pathway, and further that fibrin deposition may not be a major factor in the antitumour action of FAA.

Adenocarcinoma↗