RESUMEN
The cAMP analogue 8-Cl-cAMP induces apoptosis and inhibits proliferation of a wide variety of malignancies in vitro and in vivo with relatively little toxicity. The antitumor effects of this compound are thought to involve its ability to modulate type I protein kinase A (PKAI). However, a nontoxic metabolite of 8-Cl-cAMP, 8-Cl-adenosine, with no known activity against PKAI, exerts growth inhibitory effects in breast, ovary, pancreas, and colorectal cancer cells in vitro and accumulates in xenografted tumors after 8-Cl-cAMP treatment in vivo. To characterize further the antitumor effects of 8-Cl-adenosine in colorectal cancer, we examined its effects on cell growth in vitro (cell number, 3H-thymidine incorporation, and soft agar colony formation) using the isogenically matched colorectal cancer cell lines HCT116, HCT116-E6 (p53-depleted), and 80S14 (p21WAF1/Cip1-null). 8-Cladenosine inhibited cell growth by 89%, 74%, and 79%, respectively in HCT116, HCT116-E6, and 80S14 cells after a 72-hour exposure. Growth inhibition coincided with DNA endoreduplication and subsequent apoptosis. Furthermore, nontoxic doses of 8-Cl-adenosine administered i.p. twice weekly for 4 weeks to athymic mice suppressed growth of HCT116-derived xenografts by 50%. These results show that 8-Cl-adenosine exerts antitumor activity against colorectal cancer independent of p53 and p21WAF1/Cip1.
Asunto(s)
2-Cloroadenosina/análogos & derivados , 2-Cloroadenosina/uso terapéutico , 8-Bromo Monofosfato de Adenosina Cíclica/análogos & derivados , Adenocarcinoma/tratamiento farmacológico , Antimetabolitos Antineoplásicos/uso terapéutico , Neoplasias Colorrectales/tratamiento farmacológico , 2-Cloroadenosina/farmacología , 8-Bromo Monofosfato de Adenosina Cíclica/farmacología , Adenocarcinoma/genética , Adenocarcinoma/patología , Animales , Antimetabolitos Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Disparidad de Par Base/genética , Ciclo Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Proteínas Quinasas Dependientes de AMP Cíclico/antagonistas & inhibidores , Inhibidor p21 de las Quinasas Dependientes de la Ciclina , Ciclinas/deficiencia , Ciclinas/genética , Ciclinas/fisiología , Reparación del ADN/efectos de los fármacos , Reparación del ADN/genética , Replicación del ADN/efectos de los fármacos , Genes p53 , Humanos , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Proteínas de Neoplasias/deficiencia , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/fisiología , Células Tumorales Cultivadas/efectos de los fármacos , Ensayo de Tumor de Célula Madre , Proteína p53 Supresora de Tumor/deficiencia , Proteína p53 Supresora de Tumor/fisiología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
The protein kinase A (PKA) is classified as type I or II depending on the association of the catalytic subunit with either the R(I) or R(II) regulatory subunits. Alterations in the levels of these regulatory subunits and PKA activity itself appear to affect cellular proliferation and tumorigenesis. We examined colorectal tumor specimens from 45 patients to investigate the potential role of cAMP-related signaling molecules in regulating tumorigenesis. Western blot analysis (PKA subunit protein levels) and in vitro kemptide phosphorylation assays (PKA catalytic subunit activity) were performed on human colorectal tumor tissue homogenates. R(I)beta protein levels were decreased 200% in ascending and 50% in descending colonic tumors compared to adjacent mucosa. R(II) protein levels were decreased 77% in descending colonic tumors but no change was observed in ascending colonic tumors compared to adjacent mucosa. PKA activity and the absolute amount of catalytic subunit protein in ascending and descending tumors were unchanged compared to adjacent mucosa. Differences in cAMP-related signaling molecules exist between neoplastic and normal colorectal tissues. These differences may not only serve as potential therapeutic targets for chemotherapeutic agents, but also lead to the identification of novel regulatory mechanisms involved in cellular proliferation and tumorigenesis.
Asunto(s)
Neoplasias del Colon/enzimología , Neoplasias del Colon/genética , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Western Blotting , Catálisis , División Celular , AMP Cíclico/metabolismo , Electroforesis en Gel de Poliacrilamida , Femenino , Humanos , Técnicas In Vitro , Masculino , Persona de Mediana Edad , Oligopéptidos/farmacología , Fosforilación , Transducción de SeñalRESUMEN
The effects of administration of metoprolol and propranolol on lidocaine elimination were studied in six healthy young men who did not smoke. Each received three single intravenous doses of lidocaine (2.5 to 3.0 mg/kg injected over 10 min): one alone, one after 1 day pretreatment with propranolol (40 mg orally every 6 hr), and one after 1 day pretreatment with metoprolol (50 mg orally every 6 hr). Lidocaine clearance was 0.88 +/- 0.28 l X hr-1 X kg-1 before beta blockade, 0.61 +/- 0.20 l X hr-1 X kg-1 during metoprolol dosing, and 0.47 +/- 0.16 l X hr-1 X kg-1 during propranolol dosing. There was no correlation between the change in lidocaine elimination and the steady-state concentrations of metoprolol or propranolol, nor between the change in lidocaine clearance and the change in resting heart rate produced by either beta blocker. Metoprolol and propranolol reduce lidocaine elimination significantly.
Asunto(s)
Lidocaína/metabolismo , Metoprolol/farmacología , Propanolaminas/farmacología , Propranolol/farmacología , Adulto , Cromatografía de Gases , Interacciones Farmacológicas , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Cinética , Lidocaína/efectos adversos , MasculinoRESUMEN
Can home care agencies use the Internet to help them succeed in today's highly volatile, highly competitive market? You bet they can. The potential of Internet technology is limited only by an organization's own vision. The Internet is new ground, however, in an industry that for the most part has limited experience with even traditional communications media.
Asunto(s)
Redes de Comunicación de Computadores , Servicios de Atención de Salud a Domicilio/organización & administración , Toma de Decisiones en la Organización , Competencia Económica , Humanos , Comercialización de los Servicios de Salud , Estados UnidosRESUMEN
From the date of injury tetraplegics with spinal cord lesions of C4 and above are faced with unparalleled social and psychological adjustment. The individual will be involved in a process of re-establishing his identity by learning to develop and adapt his only remaining resources, his mind and his ability to communicate. This patient population is absolutely dependent in all aspects of meeting basic needs during the initial stages of the injury. If we attempt to return the patient to an active role in society, the rehabilitation team must be aware of the dynamics by which the patient achieves control of both himself and his environment. He will undergo a marked regression of his physical and emotional being and will face the turmoil of realigning ego parameters. The focal point of patient, family and staff interaction is the months of rehabilitation, where the team deals with the problem of social reintegration. Family involvement is essential from the beginning and reaches a high point at discharge and home planning. The scope of the paper will be to trace the psycho-social development of the patient with cervical lesion of C4 and above through the initial, rehabilitation and discharge phases of the injury. Our aim is to develop sufficient insight to the problems facing our patient population that we may aid in their search for meaningful lives.
Asunto(s)
Adaptación Psicológica , Cuadriplejía/psicología , Humanos , Cuadriplejía/rehabilitación , Respiración ArtificialRESUMEN
The method by which serum osmolality is measured can significantly affect the result if certain volatiles or solvents are present in the specimen. Commonly available solvents and alcohols were added to aliquots of pooled human serum to produce toxicologically relevant concentrations. Increasing concentrations of carbon tetrachloride, chloroform, mono-n-butyl ether (butyl cellosolve), 1, 1,1 trichloroethylene, toluene, and xylene did not change vapor pressure (VP) or freezing point depression (FPD) osmolality. Acetone, ethanol, isopropanol, and methanol in increasing concentrations produced a linear increase in FPD osmolality, but no change in VP osmolality. Only ethylene glycol produced a linear increase in VP and FPD osmolality across the range of concentrations studied. Despite the excellent correlation between osmolality and ethanol concentration in prepared serum samples, this relationship could not accurately predict patient ethanol concentrations from FPD osmolality. The osmolal gap, "delta" osmolality, (measured FPD minus calculated osmolality) did not correlate with the difference between measured FPD and VP osmolalities. Patient ethanol levels could not be predicted with accuracy using an equation based on the osmolal gap or "delta" osmolality.
Asunto(s)
Sangre/efectos de los fármacos , Etanol/toxicidad , Concentración Osmolar , Relación Dosis-Respuesta a Droga , Etanol/sangre , Glicoles de Etileno/toxicidad , Humanos , Solventes/toxicidadRESUMEN
Reversing ventricular ectopy with plasma alkalinization following acute tricyclic antidepressant overdose is a recognized mode of therapy. The mechanism responsible for this effect is unclear. Changes in plasma protein binding of free drug, effects of the sodium ion on the myocardium, and alterations of plasma concentrations of alpha-1-acid glycoprotein may all interact to alter toxicity of tricyclics in overdose. An in vitro investigation using equilibrium dialysis was designed to examine the effect of altering plasma pH on percentage of free amitriptyline at clinical overdose plasma concentrations. A 1973 report on this effect lacked adequate controls and was faulty in experimental protocol. The current investigation used plasma concentrations typically present in amitriptyline overdose, a sensitive gas liquid chromatographic assay to detect total and free drug, and adequate control of plasma pH. The results of two separate experiments demonstrated a significant decrease in percentage of free amitriptyline of 20% over a pH range of 7.0-7.4 (P less than 0.05) and 42% over a pH range of 7.4-7.8 (P less than 0.05). The rate of change in slope in both experiments was not significantly different (P less than 0.01) indicating similar effects of pH change on plasma protein binding of amitriptyline within the two groups.
Asunto(s)
Amitriptilina/sangre , Amitriptilina/metabolismo , Amitriptilina/envenenamiento , Arritmias Cardíacas/inducido químicamente , Arritmias Cardíacas/tratamiento farmacológico , Bicarbonatos/uso terapéutico , Cromatografía de Gases , Humanos , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Iones , Unión Proteica , Sodio/farmacología , Sodio/uso terapéutico , Bicarbonato de SodioRESUMEN
8-Cl-adenosine represents a novel nontoxic chemotherapeutic agent shown to inhibit growth of a number of colorectal cancer cell lines. We have utilized the mucin-secreting colorectal cancer cell line, LS174T, to assess the growth inhibitory properties of 8-Cl-adenosine independent of its parental compound, 8-Cl-cAMP. Conversion of 8-Cl-cAMP to 8-Cl-adenosine is required for growth inhibition in LS174T cells. 8-Cl-Adenosine inhibited growth by inducing a G1 cell cycle arrest that was associated with large (eightfold) increases in p21WAF1/Cip1 and p53 protein levels and a decrease in the phosphorylation status of the retinoblastoma protein. LS174T cells did not undergo apoptosis. In addition, 8-Cl-adenosine also induced some degree of enterocytic differentiation. Both villin protein levels as well as alkaline phosphatase activity rose (2- and 3.5-fold, respectively) in response to treatment with 8-Cl-adenosine. Our results suggest that in LS174T cells, 8-Cl-adenosine not only serves as a growth inhibitory agent but also as an inducer of enterocytic differentiation.
Asunto(s)
8-Bromo Monofosfato de Adenosina Cíclica/análogos & derivados , Adenosina/farmacología , Diferenciación Celular/efectos de los fármacos , Neoplasias Colorrectales/patología , 8-Bromo Monofosfato de Adenosina Cíclica/metabolismo , Adenosina/metabolismo , División Celular/efectos de los fármacos , Humanos , Proteína Oncogénica p21(ras)/biosíntesis , Factores de Tiempo , Células Tumorales Cultivadas , Proteína p53 Supresora de Tumor/biosíntesisRESUMEN
The proteolytic activity of bovine splenic cathepsin D was evaluated by using the digestion of tritiated hemoglobin. Acid-denatured human serum was an enhancer of cathepsin D activity. Concentrated serum sources showed decreased activity because of competition of serum albumin with tritiated hemoglobin for cathepsin D. The enhancing activity of serum did not separate with any isolated protein as assessed by Sephadex G-50-80 chromatography or protein electrophoresis. The extraction of serum with ethanol-ether and chloroform-methanol showed that the enhancing activity separated with the phospholipid fraction, which had 2.6 times as much activity as the total lipid fraction. The activity was stable to heat at 56 degrees C for 30 minutes and to freeze-thawing, and was not dependent on metal ions.
Asunto(s)
Fenómenos Fisiológicos Sanguíneos , Catepsina D/metabolismo , Animales , Bovinos , Relación Dosis-Respuesta a Droga , Humanos , Bazo/enzimologíaRESUMEN
Interleukin-7 (IL-7) is the major thymopoietic cytokine. Injections of IL-7 after murine bone marrow transplantation (BMT) correct defects in thymic differentiation, including thymic hypocellularity, abnormal differentiation of CD3- CD4- CD8- (triple-negative [TN]) thymocytes into CD4+ CD8+ (double-positive [DP]) cells, and antigen-specific mature T-lymphocyte proliferation. To determine whether IL-7 production is decreased in BMT recipients, BMT was performed with congenic murine donor-recipient strains and escalating doses of pre-BMT conditioning. Increasing doses of radiation resulted in decreased thymic cellularity and maturation from the TN to the DP stage. Quantitative reverse transcription-polymerase chain reaction analyses demonstrated that intrathymic production of IL-7 was significantly decreased in irradiated mice than in nonirradiated controls. Decline in IL-7 transcript levels was correlated with the dose of radiation administered. Analyses of the numbers of CD45- major histocompatibility complex class II+ thymic stromal cells suggested that the mechanism for the decreased IL-7 production was loss of IL-7-producing thymic stromal cells. Experiments indicated that pre-BMT conditioning with radiation led to decreased stromal production of IL-7 and consequent blocks in the maturation of thymocytes. They provided a mechanism for both the abnormal thymopoiesis observed after BMT and the previously observed beneficial effects of IL-7 administration in murine models. Impaired production of IL-7 by thymic stroma may be a general model for the clinically observed adverse effects of cytotoxic therapy on thymopoiesis.
Asunto(s)
Regulación de la Expresión Génica/efectos de la radiación , Interleucina-7/biosíntesis , Linfocitos T/patología , Timo/efectos de la radiación , Acondicionamiento Pretrasplante/efectos adversos , Irradiación Corporal Total/efectos adversos , Animales , Animales Congénicos , Trasplante de Médula Ósea , Recuento de Células , Diferenciación Celular/efectos de la radiación , Fraccionamiento de la Dosis de Radiación , Relación Dosis-Respuesta en la Radiación , Antígenos de Histocompatibilidad Clase II/análisis , Inmunofenotipificación , Interleucina-7/deficiencia , Interleucina-7/genética , Interleucina-7/fisiología , Ratones , Ratones Endogámicos C57BL , Tolerancia a Radiación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células del Estroma/metabolismo , Células del Estroma/efectos de la radiación , Timo/metabolismo , Timo/patologíaRESUMEN
The activity of 14 antimicrobial agents against 253 clinical isolates of anaerobic bacteria from pediatric infections was assessed by the agar dilution method. Fifty-eight percent of the isolates were from intraabdominal sites. The drugs tested were ampicillin/sulbactam, ticarcillin/clavulanate, ampicillin, sulbactam, piperacillin, cefoxitin, cefotaxime, cefoperazone/sulbactam, clarithromycin, azithromycin, erythromycin, clindamycin, metronidazole, and chloramphenicol. Ticarcillin/clavulanate was active against all isolates. Clarithromycin was the most active macrolide; combination of this agent with its 14-hydroxy metabolite did not result in synergy. Sixty-two percent of Bacteroides fragilis group isolates, 13% of B. fragilis isolates, and 22% of peptostreptococcal isolates were resistant to clindamycin at a concentration of 4 micrograms/mL. The distribution of these strains in clinical specimens and the patterns of antimicrobial susceptibility documented were different from the findings for isolates from adults in the Los Angeles area.
Asunto(s)
Antibacterianos/farmacología , Bacterias Anaerobias/efectos de los fármacos , Infecciones Bacterianas/microbiología , Ampicilina/farmacología , Bacterias Anaerobias/aislamiento & purificación , Bacteroidaceae/efectos de los fármacos , Bacteroidaceae/aislamiento & purificación , Niño , Claritromicina/farmacología , Ácido Clavulánico , Ácidos Clavulánicos/farmacología , Clostridium/efectos de los fármacos , Clostridium/aislamiento & purificación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/aislamiento & purificación , Humanos , Pruebas de Sensibilidad Microbiana , Sulbactam/farmacología , Ticarcilina/farmacologíaRESUMEN
KRM 1648 is a 4-aminobenzoxazine derivative of rifamycin S with potent in vitro activity against the Mycobacterium avium complex (MAC); the MIC for 90% of 24 MAC isolates from AIDS patients was 0.25 microgram/ml as determined by a radiometric broth macrodilution assay. KRM 1648 was bactericidal for MAC isolates in Middlebrook 7H9 broth, with a reduction in viability of 1 to 4 orders of magnitude over 72 h. In human macrophages, KRM 1648 also was bactericidal, with a reduction of 3 to 4 orders of magnitude in CFU per ml of macrophage lysate at a concentration of 1 microgram/ml; however, the bactericidal activity varied approximately 10-fold among the three MAC serovars tested. In growth medium, ethambutol potentiated the effect of KRM 1648, but this potentiation was modest when tested against MAC in macrophages and also varied between MAC strains. KRM 1648 has potential as an antimycobacterial agent for MAC disease, perhaps in combination with other agents so that the use of lower dosages of KRM 1648 than are needed with other rifamycins may be possible.
Asunto(s)
Antibióticos Antituberculosos/farmacología , Etambutol/farmacología , Macrófagos/microbiología , Complejo Mycobacterium avium/efectos de los fármacos , Rifamicinas/farmacología , Línea Celular , Claritromicina/farmacología , Etambutol/administración & dosificación , Humanos , Pruebas de Sensibilidad Microbiana , Rifamicinas/administración & dosificaciónRESUMEN
Levofloxacin, ofloxacin, and Bay Y 3118 are new fluoroquinolones with variable in vitro bacteriostatic and bactericidal activities against the Mycobacterium avium complex (MAC). The potential therapeutic activities of these agents both alone and combined with ethambutol were evaluated in a human macrophage test system and in the beige mouse animal test system with MAC strain 101. Bay Y 3118 at a human-equivalent dose of 30 mg/kg/day for 4 weeks caused a significant reduction in mortality compared with that in untreated controls (P = 0.02). Bay Y 3118 also caused significant reductions in the number of MAC organisms in the blood, liver tissue, and spleen tissue compared with those in untreated controls. Levofloxacin at a human-equivalent dose of 200 mg/kg/day was associated with a significant reduction in mortality (10 versus 39%); however, treatment with either levofloxacin or ofloxacin (200 mg/kg/day) did not result in significant reductions in the numbers of MAC organisms in blood, liver, and spleen compared with those in untreated controls. When Bay Y 3118 was combined with ethambutol, there was no enhancement in therapeutic activity except in the spleen in terms of CFU per gram (reductions of 89% compared with the untreated control, 63% compared with Bay Y 3118 alone, and 72.5% compared with ethambutol alone). Levofloxacin in combination with ethambutol was more active than either drug alone in the reduction of organisms in blood, liver, and spleen. Bay Y 3118 was the most active fluoroquinolone for monotherapy of MAC infection in beige mice, and the combination of ethambutol plus either levofloxacin or ofloxacin was at least additive. In summary, this study demonstrates that quinolones, although active, are inhibitory against MAC in vivo and that there is little correlation between the activity of quinolones in vitro and the activity in mice.
Asunto(s)
Antiinfecciosos/farmacología , Etambutol/farmacología , Fluoroquinolonas , Macrófagos/microbiología , Complejo Mycobacterium avium/efectos de los fármacos , Infección por Mycobacterium avium-intracellulare/tratamiento farmacológico , Animales , Antiinfecciosos/uso terapéutico , Línea Celular , Combinación de Medicamentos , Etambutol/uso terapéutico , Femenino , Humanos , Levofloxacino , Macrófagos/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Pruebas de Sensibilidad Microbiana , Infección por Mycobacterium avium-intracellulare/microbiología , Ofloxacino/farmacología , Quinolonas/farmacología , RatasRESUMEN
Ferrochelatase was purified from the livers of normal and protoporphyria cattle by chromatography on Blue Sepharose CL-6B in order to investigate the enzyme defect in this disorder. The increase in specific activity (up to 2900-fold) indicated that the normal and protoporphyria enzymes were purified to a similar degree. The mutant enzyme had catalytic activity which was 10 to 15% of normal ferrochelatase, although the Michaelis constants for protoporphyrin and iron were similar. The molecular mass of the normal and protoporphyria enzyme protein was 40 kDa as evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In the presence of 15 mM sodium cholate, gel filtration demonstrated a similar size. However, at a lower concentration of sodium cholate (4 mM) the molecular mass was about 240 kDa, suggesting that the purified enzymes aggregate under this condition. Polyvalent antibodies were raised in rabbits using as antigens purified normal native enzyme and normal 40-kDa protein which had been further purified by preparative SDS-PAGE. In Western blots these antibodies complexed with both the normal and mutant 40-kDa proteins. The amount of 40-kDa protein in normal and protoporphyria mitochondrial fractions was also similar as evaluated by Western blots. These studies indicate that the ferrochelatase defect in bovine protoporphyria probably results from a point gene mutation that causes a minor change in enzyme structure.