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K S Smith

Publications and source records attributed to K S Smith.

At least 55 records · Page 3Linked to original sources
PubMed1994

Agonist binding to alpha 2-adrenoceptors is elevated in the locus coeruleus from victims of suicide.

The binding of an agonist, p-[125I]iodoclonidine, and an antagonist, [3H]yohimbine, to alpha 2-adrenoceptors was measured autoradiographically in the locus coeruleus from 10 pairs of antidepressant-free victims of suicide and age-matched controls. Agonist binding to alpha 2-adrenoceptors was significantly greater in the locus coeruleus from victims of suicide compared with control subjects. In contrast, antagonist binding to alpha 2-adrenoceptors in the locus coeruleus did not differ significantly between control and suicide subjects. HPLC analysis of norepinephrine in tissue sections of the locus coeruleus did not reveal any differences between control subjects and suicide victims, suggesting that differences in agonist binding are not a result of differences in retention of the endogenous agonist norepinephrine in tissue sections. The increase in agonist binding to alpha 2-adrenoceptors in the locus coeruleus of victims of suicide links an altered expression of the high-affinity state of autoinhibitory alpha 2-adrenoceptors with suicide.

Adult↗
PubMed1993

Multidrug resistance is a component of V79 cell resistance to the alkylating agent adozelesin.

Adozelesin is a highly potent alkylating agent which has entered clinical trials based on its unique mechanisms of action and broad-spectrum antitumor activity in vivo. V79 cells resistant to adozelesin (V79/AdoR) were not resistant to the alkylating agent cisplatin but showed the phenotypic and genotypic characteristics of multidrug resistance. Thus V79/AdoR was cross-resistant to several structurally and functionally unrelated drugs, resistance was reversed by verapamil, and the resistant cell line expressed mdr mRNA and p170 glycoprotein. Also, adozelesin uptake and the amount of drug alkylated to DNA was much lower in the resistant cell line as compared to the sensitive parent. However, even with the same amount of drug bound to DNA (10 fmol/micrograms DNA) the survival of V79/S approximately 15% survival) was much lower than that of V79/AdoR (approximately 80%). Therefore the resistance of V79/AdoR cannot be explained solely by the multidrug resistance mechanism (i.e., lower drug uptake and less drug alkylation to DNA), which suggests that multiple mechanisms may account for resistance to adozelesin. V79/AdoR showed different levels of cross-resistance to several adozelesin analogues. The analogues could be divided into 2 groups; those with very low partition coefficients (log P < 2 as compared to 2.74 for adozelesin) had low levels of cross-resistance, whereas analogues with higher partition coefficients (log P > 2.4) were cross-resistant to adozelesin.

Alkylating Agents↗
PubMed1992

Lethality, DNA alkylation, and cell cycle effects of adozelesin (U-73975) on rodent and human cells.

Adozelesin (U-73975) is an extremely potent cytotoxic agent which causes 90% lethality, after 2 h exposure in vitro, of Chinese hamster ovary and lung (CHO and V79), mouse melanoma (B16), and human ovarian carcinoma (A2780) cells at 0.33, 0.19, 0.2, and 0.025 ng/ml, respectively. Under similar conditions, Adriamycin and cisplatin had 90% lethality values in CHO cells of 150 ng/ml (= 249 nM) and 6800 ng/ml (= 2266 nM), respectively. The relative drug sensitivity of the cell lines (A2780 > V79, B16, CHO) was correlated to the relative amounts of [3H]adozelesin alkylated to DNA. The greater sensitivity of A2780 was due to (a) greater DNA alkylation at different drug doses and (b) greater intrinsic sensitivity of A2780 which resulted in greater cell kill at comparable DNA alkylation. Phase specific toxicity studies show that adozelesin was least lethal to CHO cells in mitosis and very early G1. Lethality increased as cells progressed through G1 and was maximal in late G1 and early S. Mitotic cells had lower drug uptake and correspondingly less drug binding to DNA than G1 or S-phase cells. However, based on the amount of drug alkylated per micrograms of DNA, cells in M, G1, and S were equally sensitive. Therefore, the lower sensitivity of M-phase cells was due to lower drug uptake. Adozelesin had three different effects on progression of CHO, V79, B16, and A2780 through the cell cycle: (a) slowed progression through S which resulted in significantly increasing the percentage of S-phase cells. This effect was transient; (b) cell progression was blocked in G2 for a long time period; (c) the response of the cell lines to the G2 block differed. CHO and V79 cells escaped G2 block by dividing and entered the diploid DNA cycle or did not undergo cytokinesis and became tetraploid. On the contrary, B16 and A2780 cells remained blocked in G2 and did not become tetraploid. Cell progression was inhibited in a similar manner when a synchronized population of M, G1, or S-phase cells were exposed to adozelesin.

Alkylation↗
PubMed1992

Fluorescence quenching of spectrin and other red cell membrane cytoskeletal proteins. Relation to hydrophobic binding sites.

The intrinsic fluorescence of spectrin is strongly quenched by low concentrations of 2-bromostearate. This results from binding at a series of hydrophobic sites. Analysis of dynamic fluorescence quenching by acrylamide, iodide and caesium ions, separately and in conjunction with 2-bromostearate, leads to the conclusion that most of the tryptophan side-chains are exposed to solvent. The sites at which the fatty-acid-quenched tryptophans are located apparently interact with the lipid bilayer in the cell, as judged by quenching by bromostearate dissolved in the lipid phase. A minor proportion of the side-chains in native spectrin give rise to sharp proton magnetic resonance signals, indicative of segmental mobility; these chain elements contain some tryptophan residues, as revealed by weak downfield signals from the heterocyclic ring protons. These signals are not appreciably perturbed by stearic acid or by phosphatidylserine liposomes, suggesting that the hydrophobic binding sites are not in mobile chain elements. By contrast with a series of globular proteins which, with the exception of serum albumins, show little or no quenching by 2-bromostearate, the peripheral red cell membrane skeletal proteins ankyrin (and its spectrin-binding domain), protein 4.1 and (to a lesser extent) actin show evidence of a high affinity for the hydrophobic ligand and may, like spectrin, interact directly with the bilayer in situ.

Binding Sites↗
PubMed1992

Adozelesin, a potent new alkylating agent: cell-killing kinetics and cell-cycle effects.

Adozelesin (U-73975) was highly cytotoxic to V79 cells in culture and was more cytotoxic than several clinically active antitumor drugs as determined in a human tumor-cloning assay. Phase-specificity studies showed that cells in the M+early G1 phase were most resistant to adozelesin and those in the late G1 + early S phase were most sensitive. Adozelesin transiently slowed cell progression through the S phase and then blocked cells in G2. Some cells escaped the G2 block and either divided or commenced a second round of DNA synthesis (without undergoing cytokinesis) to become tetraploid. Adozelesin inhibited DNA synthesis more than it did RNA or protein synthesis. However, the dose needed for inhibition of DNA synthesis was 10-fold that required for inhibition of L1210 cell growth. The observation that cell growth was inhibited at doses that did not cause significant inhibition of DNA synthesis and that cells were ultimately capable of completing two rounds of DNA synthesis in the presence of the drug suggests that adozelesin did not exert its cytotoxicity by significant inhibition of DNA synthesis. It is likely that adozelesin alkylates DNA at specific sites, which leads to transient inhibition of DNA synthesis and subsequent G2 blockade followed by a succession of events (polyploidy and unbalanced growth) that result in cell death.

Alkylating Agents↗
PubMed1990

P388 leukaemia cells resistant to the anthracycline menogaril lack multidrug resistant phenotype.

Menogaril is an anthracycline presently in Phase II clinical trials. Menogaril-resistant mouse leukaemia P388 cells were developed in vitro by 4 months of exposure to step-wise increasing concentrations of menogaril after which resistant cells (P388/MEN) were cloned in 320 ng ml-1 menogaril. P388/MEN cells were 40-fold more resistant to menogaril in vitro compared to P388/O and were also resistant in vivo. Resistance to menogaril was stable for at least 2 months in the absence of the drug. The results indicate that P388/MEN, although resistant to an anthracycline, did not display the typical multidrug resistant phenotype. It was not cross-resistant to several structurally unrelated drugs such as actinomycin D, cisplatin, or vinblastine, but it was cross-resistant to the anthracycline, adriamycin. Uptake and efflux of menogaril was similar in sensitive and resistant cell lines. Also, resistance was not reversed by verapamil. No major karyotypic difference was noted between P388/O and P388/MEN. There was no significant amplification or overexpression of the mdr gene in P388/MEN compared to P388/O. In contrast to P388/MEN, P388 cells resistant to adriamycin displayed the typical multidrug resistant phenotype. Glutathione content of P388/MEN cells was similar to that of P388/O and depletion of glutathione did not potentiate menogaril cytotoxicity. Therefore, we conclude that glutathione is not likely to be involved in menogaril resistance to P388/MEN cells.

Animals↗
PubMed1990

The impact of psychologic factors on measurement of functional status. Assessment of the sickness impact profile.

In this study the relationship between four psychologic health constructs (depression, anxiety, patient response bias, and hostility) and the Sickness Impact Profile (SIP) measurement of functional status was evaluated. The SIP, Carroll Depression Rating Scale (CDRS); and the Minnesota Multiphasic Personality Inventory (MMPI) were administered to 332 patients hospitalized for treatment of combined medical and psychiatric problems. Pearson's product-moment correlation was high between CDRS and SIP Total score (r = 0.67) and between CDRS and SIP Psychosocial subscale (r = 0.72); correlation was lower between CDRS and SIP Physical subscale (r = 0.44). Six MMPI scales (depression, anxiety, psychasthenia, lie, K, hostility) correlated with SIP Total score (r = 0.18 to 0.50), with SIP Psychosocial score (r = 0.28 to 0.65) and less well with SIP Physical subscale (r = 0.07 to 0.25). Factor analysis of the SIP categories showed two factors with eigenvalues greater than 1. Promax factor rotation showed all SIP Psychosocial categories and all measured psychologic variables loaded most heavily on factor 1. SIP Physical categories loaded most heavily on factor 2. Stepwise multiple regression analysis showed that psychologic variables account for 49% of the SIP total variance, 62% of SIP Psychosocial subscale variance, but only 19% of SIP Physical subscale variance. The CDRS accounts for the major portion of the explained variance with only minor additional contributions from the MMPI scales. We conclude that 1) the SIP discriminates psychosocial and physical dysfunction even in medical patients with extensive psychiatric comorbidity; 2) the SIP measures at least two dimensions of health, one of which is strongly related to depression; and 3) constructs measured by MMPI scales do not have substantial independent contribution to SIP variance.

Adult↗
PubMed1989

Preparation and properties of human red-cell ankyrin.

We describe a procedure for the preparation of ankyrin from human red cells with a yield of 2-3 mg of protein from 30 ml of packed cells. This represents an improvement of an order of magnitude over the usual earlier procedure. Moreover, the product is, in our hands, much more stable against adsorption and proteolysis, and can in general be stored for at least 2 months at 4 degrees C without significant decrease in concentration and binding activity. The preparation depends on the release of the ankyrin-band-3 complex from the membrane cytoskeleton when intact cells are lysed in a medium containing concentrated Triton X-100. The complex is dissociated at high ionic strength, and the final purification is achieved by gel filtration in a medium containing 2 M-Tris or 0.6 M-NaBr. The ankyrin contains all the progression of components present in the intact membrane. All react with affinity-purified polyclonal anti-ankyrin antibodies, and all give widely similar patterns of peptides in partial proteolytic digests. The ankyrin is fully active, as judged by its capacity to bind to band-3-containing membrane vesicles and to Sepharose-coupled spectrin. All components bind to the membrane vesicles. Purified components 2.1 and 2.2, as well as the calmodulin-binding cytoskeletal constituent adducin, can be isolated in pure form by a single anion-exchange column step.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1989

Formulary conversion of cefoxitin usage to cefotetan: experience at a large teaching hospital.

The pharmacy and therapeutics committee at Hartford Hospital recommended replacement of cefoxitin with cefotetan, based on data reported in the literature regarding antimicrobial activity, pharmacokinetic profile, and adverse reactions. Once the recommendation was approved by the medical staff, an intense educational program was instituted, and all orders for cefoxitin were converted to cefotetan with appropriate dosage modifications. A total of 960 patients were treated in the first year; no major patterns of ineffectual therapy or adverse events associated with cefotetan usage have emerged. The mean cost of cefotetan therapy was $180.59, which is $130.26 less per patient than a comparable regimen of cefoxitin (mean cost of therapy $310.85). Based on the data analysis of cefotetan usage for a 12-month period, the actual annual savings due to therapeutic substitution of cefotetan for cefoxitin was $124.961. To further evaluate the clinical efficacy, safety, and savings of this therapeutic interchange, two separate retrospective reviews of patient medical records were performed. The first audit has been previously published in its entirety. In the subsequent audit, 284 additional patient medical charts have been reviewed. These patients received either cefotetan therapy or concomitant therapy of an aminoglycoside combined with either clindamycin or mezlocillin. Clinical outcomes were classified as an empiric cure or improvement for 99.4, 98.5, and 92.9 percent of patients, respectively. In this audit, elevated prothrombin time/partial thromboplastin time values and bleeding episodes were noted infrequently, as were other adverse reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Disorders↗
PubMed1988

Multidisciplinary program for promoting single prophylactic doses of cefazolin in obstetrical and gynecological surgical procedures.

A multidisciplinary cost-containment program for promoting the use of single prophylactic doses of cefazolin for obstetrical and gynecological surgical procedures is described. Following a one-month review of patient charts to identify the antimicrobial regimens used most frequently for prophylaxis in obstetrical and gynecological surgical procedures, the department of pharmacy services, with the cooperation of the pharmacy and therapeutics (P&T) committee and the departments of obstetrics and gynecology and infectious diseases, implemented an educational program to promote the use of single doses of cefazolin for surgical prophylaxis. The program included inservice education and distribution of letters of support and a therapeutics newsletter. Drug stocking patterns in the operating and delivery rooms were changed to make cefazolin more accessible, and the P&T committee formally restricted the use of prophylactic antimicrobial agents in obstetrical and gynecological surgical procedures to single doses of cefazolin unless a consulting infectious-disease physician recommended otherwise. Compliance with the program increased as each step was implemented; data collected 16 months after the program was initiated demonstrated a compliance rate of 78.8%. Based on comparison of data collected before initiation and six months after initiation of the program, an actual cost savings of +7,125 was realized, which extrapolates to +14,250 annually. No apparent adverse effects on patient care were noted. The multidisciplinary approach to promoting the use of single doses of cefazolin was effective.

Cefazolin↗
PubMed1988

Antibiotic streamlining from combination therapy to monotherapy utilizing an interdisciplinary approach.

Streamlining of antibiotic therapy from a more complex to a less complex regimen should reduce hospital costs. Utilizing the expertise of an infectious disease physician and clinical pharmacists, an antibiotic-streamlining program was implemented by (1) daily collection of data on patients receiving two or more parenteral antibiotics, (2) formulation of recommendations of cost-effective alternative therapy when clinically appropriate, (3) oral and/or written communication of the reasons for the recommendation to the patient's physician, (4) follow-up monitoring, and (5) determination of the cost savings by subtracting the actual cost of antibiotic therapy (including labor and supplies) from the cost of the initial regimen if it had been continued without alteration. Streamlining recommendations were made in 340 of 625 patients who were reviewed during the initial seven months. Cases that necessitated streamlining recommendations decreased from 98.6% during the first month to 54.4% during the seventh month, reflecting the educational impact of the program on prescribing habits. Recommendations were followed in 82.6% of the cases, of which 97.2% completed therapy with the streamlined regimen. The projected annual savings of the program was +107,637.

Anti-Bacterial Agents↗
PubMed1986

Rapid shallow breathing evoked by capsaicin from isolated pulmonary circulation.

Recently Green et al. (J. Appl. Physiol. 57:562-567, 1984) reported that pulmonary C-fibers initiate the prompt apnea evoked by pulmonary arterial injections of capsaicin; however, their role in the subsequent rapid shallow breathing of the pulmonary chemoreflex is still in dispute. To determine whether this reflex tachypnea is triggered by pulmonary C-fibers rather than by afferents further downstream, we separately perfused the pulmonary and systemic circulations in dogs anesthetized with either halothane or alpha-chloralose as the lungs were ventilated with a servo-controlled ventilator driven by phrenic nerve activity. Injection of capsaicin (10 micrograms/kg) into the pulmonary artery of the isolated pulmonary circulation evoked an immediate apnea followed by rapid shallow breathing. Injection of the same dose of capsaicin into the left atrium of the isolated pulmonary circulation had no effect. By contrast, when capsaicin was administered at a slower rate into the pulmonary artery (10-20 micrograms X kg-1 X min-1) rapid shallow breathing occurred but without apnea. Our results are consistent with the hypothesis that in spontaneously breathing animals, stimulation of pulmonary C-fibers can evoke rapid shallow breathing.

Anesthesia↗