PubMed Health⌕ Search

Biomedical subjects

K Salata

Publications and source records attributed to K Salata.

At least 19 recordsLinked to original sources
PubMed1999

Ceramide increases steroid hormone production in MA-10 Leydig cells.

Ceramide is known to have major roles in the control of cell proliferation, differentiation, and apoptosis. Recent studies also have shown that ceramide affects steroid production by JEG-3 choriocarcinoma cells, acutely dispersed rat Leydig cells, and ovarian granulosa cells, but the mechanism by which this occurs is unknown. Because ceramide induces apoptosis in many different cell types, we hypothesized that ceramide might affect steroidogenesis and/or induce apoptosis in MA-10 murine Leydig cells. To test this, MA-10 cells were incubated with either the water soluble C2-ceramide, (N-acetyl-sphingosine, 0.01-10 cm); bacterial sphingomyelinase (1-100 mU/ml); or C2-dihydroceramide (N-acetyl-sphinganine, 0.1-10 microM). The data show that N-acetyl-sphingosine significantly increased basal (0.87 +/- 0.2 vs. 0.42 +/- 0.09 ng/mg cell protein, P < 0.01) and human chorionic gonadotropin (hCG) stimulated progesterone (P) synthesis (204 +/- 12 vs. 120 +/- 5 ng/mg cell protein, P < 0.001); as did sphingomyelinase (basal P = 0.83 +/- 0.1 ng/mg cell protein, P < 0.01; hCG stimulated P = 173 +/- 7 ng/mg cell protein, P < 0.001). C2-dihydroceramide also increased basal P synthesis but was less effective than ceramide on a molar basis. Neither sphingomyelinase (100 mU/ml) nor ceramide (10 microM) had any effect on cAMP production or human chorionic gonadotropin binding; and neither induced any signs of apoptosis (FragEL DNA fragmentation assay and electron microscopy). Cells incubated with anti-Fas (300 ng/ml) demonstrated DNA fragmentation, nuclear condensation, and frequent apoptotic bodies, but had no change in P synthesis. These data show that ceramide significantly increases MA-10 Leydig cell P synthesis but does not induce apoptosis. The mechanism by which ceramide increases steroid hormone synthesis remains unknown but does not appear to be linked to the induction of apoptosis in MA-10 cells.

Animals↗
PubMed1998

Recovery and viability of Orientia tsutsugamushi from packed red cells and the danger of acquiring scrub typhus from blood transfusion.

BACKGROUND: The purpose of this study was to determine whether infective Orientia tsutsugamushi, the etiologic agent of scrub typhus, could survive normal blood banking processing and storage procedures. STUDY DESIGN AND METHODS: Mononuclear cells isolated from whole blood by density gradient centrifugation were inoculated with O. tsutsugamushi, Karp strain. Infection of the mononuclear cells was confirmed by Giemsa stain, direct fluorescent antibody assay, and polymerase chain reaction using primers specific for the groESL operon of O. tsutsugamushi. The quantity of rickettsial particles in each preparation was determined by direct counts from the Giemsa-stained preparations. Infected mononuclear cells were returned to their respective aliquots of packed red blood cells, which were then either stored at 4 degrees C or glycerolized and frozen at -70 degrees C. RESULTS: Rickettsiae survived up to 10 days (but not 30 days) of refrigerated storage and 45 days of frozen storage, as determined by inoculation of mice with 0.5-mL aliquots of the blood components. Infection of the mice was determined by illness, death, direct fluorescent antibody assay of peritoneal smears, polymerase chain reaction of blood, and enzyme-linked immunosorbent assay detection of antibodies in plasma. CONCLUSION: Because the quantity of rickettsiae injected into the mice was comparable to the quantity reported in the literature for human blood during natural infections, scrub typhus could present a risk in blood collected from donors in endemic areas. This may especially be true, because people can be rickettsemic before illness, after successful antibiotic treatment, and chronically after resolution of disease.

Animals↗
PubMed1995

Thyrotropin receptor T cell epitopes in autoimmune thyroid disease.

The human TSH receptor represents the primary target of thyroid-stimulating immunoglobulins responsible for the hyperthyroidism of Graves' disease. In the present series of investigations, the distribution of T cell epitopes has been mapped using synthetic peptides spanning the entire extracellular region of the human TSH receptor. In vitro proliferative responses of the mononuclear cells were measured using flow cytometric analysis of bromodeoxyuridine incorporation into nuclei. In 8 of 11 samples from patients with Graves' disease, at least one (and up to 9) regions of the human TSH receptor induced proliferation, with the mean stimulation index being 39.8 +/- 47.3. No single universal stimulatory peptide was identified. In contrast, stimulation was not observed in three control subjects, while one control subject showed minimal stimulation (index of 5.7) to peptides encompassing a limited area (amino acids 31-65). The immunodominant epitope of patients with recent-onset Graves' disease was localized between amino acids 271 and 365, whereas the immunodominant epitope of patients with disease duration greater than 1 year localized between amino acids 91 and 215. We conclude that the bromodeoxyuridine incorporation method is a useful and important tool for detecting antigen-induced lymphocyte proliferation. The TSH receptor-specific T cells from different Graves' disease patients recognize variable distinct sites within the extracellular region of the TSH receptor, and the immunodominant epitope apparently shifts toward the N-terminus of the receptor protein during the course of treated Graves' disease.

Bromodeoxyuridine↗
PubMed1995

The influence of triiodothyronine, thyroxine, thyrotropin, and methimazole on thyroid cell MHC class II antigen expression.

We have studied the influence of triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH), and methimazole (MMI) on the expression of major histocompatibility (MHC) Class II antigen expression in human thyroid cells. T3, T4, TSH, and MMI in various combinations were added together with interferon-gamma (IFN-gamma) to human thyrocytes or to cultured FRTL-5 cells. Neither T3 nor T4, alone, caused inhibition of the IFN-gamma stimulation of thyrocyte HLA-DR expression. Moreover, the combination of both drugs at various concentrations did not inhibit this expression except only in low ranges (T3 at 0.3 nmol/liter and T4 at 12.9 nmol/liter). MMI only at a concentration of 3.0 mmol/liter caused significant inhibition of IFN-gamma-induced HLA-DR expression. However, the addition of T3 (range, 0.3-9.2 nmol/liter) or T4 (12.9-129.0 nmol/liter) prevented the MMI-induced inhibition. This phenomenon may be explained by the action of MMI on inhibiting the synthesis of T3 and T4. At a concentration of 100 microU/ml, TSH enhanced IFN-gamma-induced HLA-DR expression. It is possible that TSH induced the expression of large numbers of IFN-gamma receptors, thereby enhancing the production of HLA-DR in response to IFN-gamma. Our studies suggest that MMI does not alter thyrocyte HLA-DR expression in vitro, especially when combined with T3 or T4; however, MMI may still induce or perpetuate immune effects in vivo secondary to its influence on thyroid hormone production or thyroid antigen presentation.

Animals↗
PubMed1995

In vitro effectiveness of azithromycin against doxycycline-resistant and -susceptible strains of Rickettsia tsutsugamushi, etiologic agent of scrub typhus.

In an effort to find a potential alternative treatment for scrub typhus, we evaluated the effectiveness of the standard drug doxycycline and the new macrolide azithromycin against a doxycycline-susceptible strain (Karp) and a doxycycline-resistant strain (AFSC-4) of Rickettsia tsutsugamushi. The antibiotics were tested in an in vitro assay system in which infected mouse fibroblast cells (L929) were incubated for 3 days in various concentrations of the drugs. Rickettsial growth was evaluated by direct visual counts of rickettsiae in Giemsastained cells or by flow cytometry. Initial tests were conducted at the concentration of each antibiotic considered to be the upper breakpoint for susceptibility (16 micrograms/ml for doxycycline and 8 micrograms/ml for azithromycin). Growth of both Karp and AFSC-4 was strongly inhibited with both antibiotics, as measured by visual counts, although the percentage of cells infected with AFSC-4 in the presence of doxycycline was three times greater than the percentage of cells infected with Karp but was only 60% as great as the percentage of cells infected with Karp in the presence of azithromycin. Flow cytometry confirmed that rickettsial growth occurred in the absence of antibiotics, but it failed to detect it in the presence of high concentrations of either drug. Visual counts of rickettsial growth at lower concentrations of the antibiotics (0.25 to 0.0078 microgram/ml) showed that the Karp strain was 16 times more susceptible that the AFSC-4 strain to doxycycline. Azithromycin was much more effective than doxycycline against AFSC-4, inhibiting rickettsial growth at 0.0156 microgram/ml to levels below that achieved by 0.25 microgram of doxycycline per ml. Azithromycin was also more effective than doxycycline against the Karp strain, causing greater reductions in the number of rickettsiae per cell at lower concentrations. If in vivo testing confirms the in vitro effectiveness of azithromycin, it may prove to be the drug of choice for the treatment of scrub typhus in children and pregnant women, who should not take doxycycline, and in patients with refractory disease from locations where doxycycline-resistant strains of R. tsutsugamushi have been found. When tested in an in vitro assay system, azithromycin was more effective than doxycycline against doxycycline-susceptible and -resistant strains of R. tsutsugamushi.

Animals↗
PubMed1995

Tannic acid's effect on bird antigen.

BACKGROUND: Birds have been associated with many diseases including hypersensitivity pneumonitis and allergic diseases such as asthma and rhinitis. Bird antigen from homes of patients with hypersensitivity pneumonitis persists long after the bird is removed from the home. This may account for the persistence of symptoms, signs, and bird-specific IgG in patients with hypersensitivity pneumonitis. Tannic acid application has been effective in decreasing cat and mite allergen levels. No data have been available on tannic acid's effect on bird antigen. OBJECTIVE: It is the purpose of this study to determine whether tannic acid reduces bird antigen in the home. METHOD: Dust samples were collected from homes with bird antigen before and after application of tannic acid. Samples were assayed for bird antigen levels using a competitive inhibition ELISA. Pre- and post-bird antigen levels were compared using a paired t test to determine whether antigen was reduced significantly. RESULTS: There was not a statistical difference between bird antigen levels before and after application of tannic acid as compared by paired t test (P = .09). CONCLUSION: Tannic acid is not effective in decreasing bird antigen levels. In patients with hypersensitivity pneumonitis or allergic disease to birds, the bird should be removed from the home and environmental cleanup should be undertaken, but tannic acid application is not indicated.

Allergens↗
PubMed1994

Mite allergen control with acaricide fails.

BACKGROUND: We compared the effects of an acaricide, benzyl benzoate, with the effects of baking soda control applied to bedroom and living room carpets on house dust mite allergen levels, lung function, and medication use in 12 adult patients with asthma for 12 months. METHODS: This was a randomized, double-blind, placebo-controlled study. Patients were enrolled from the allergy clinic of a large tertiary care center in a metropolitan area. All patients had positive dust mite puncture test results. Six patients used benzyl benzoate, and six used baking soda. Other aggressive mite control measures were implemented uniformly in each group. Subjects were to make two carpet applications, at baseline and at 6 months according to the manufacturer's recommendations. Dust samples were collected in bedroom and living room carpets at 0, 3, 6, 9, and 12 months; and quantities of Der p I and Der f I allergens were determined. Spirometry was done every 3 months, and peak flow rates were recorded for 10 days after each dust sampling. RESULTS: There were no significant differences in mean allergen levels between the two groups over time at either site. There were no significant changes in lung function or medication use for either group. CONCLUSIONS: Benzyl benzoate powder applications may not be effective when done according to manufacturer's instructions. Further studies are necessary to test effectiveness when applied more frequently and for longer periods.

Adult↗
PubMed1992

Effective education of adults with asthma who are allergic to dust mites.

The effects of supplementary computer instruction in house dust mite-avoidance measures on adherence to implementing measures, on home dust mite-allergen levels, and on symptomatology were investigated in 52 adult patients with mite-associated asthma. Twenty-six patients received conventional instruction (counseling and written instruction) and the other 26 patients received conventional plus 22 minutes of interactive computer-assisted instruction. Instructions were aimed at mite-avoidance measures. Pre- and postinstruction dust samples were collected, and adherence was monitored. All patients kept symptom diaries twice a day. Patients' progress was followed for 12 weeks, and all patients completed the study. Adherence, number of observed and self-reported mite-avoidance measures implemented after visit, was higher for the computer group (p = 0.023). The computer-instructed group achieved significantly lower levels of mite allergen in bedroom carpets (p = 0.004) with mean levels of mite allergen declining from 6.5 +/- 7.6 to 2.2 +/- 4.3 micrograms/gm of dust (two-site monoclonal antibody assays), whereas levels for the conventional-instructed group did not change. Moreover, by study weeks 9 and 10, the computer-instructed group was significantly less symptomatic (p = 0.033). Mean symptom scores for this group decreased from 12.4 to 7.7, compared with 16.4 to 14.3. Conventional instruction supplemented with computer instruction is suggested in mite education.

Adolescent↗
PubMed1992

Bird antigen persistence in the home environment after removal of the bird.

Hypersensitivity pneumonitis (HP) secondary to bird exposure is treated with glucocorticosteroids and avoidance. Despite therapy, symptoms may persist for a prolonged time. Just as cat antigen, Fel d 1, may persist for greater than 20 weeks after cat removal, there may be persistent bird antigen to explain prolonged symptoms in bird HP. It was the intent of this study to determine household distribution and persistence of bird antigen after removal of the bird from the patient's home. The homes of patients with birds were followed serially after bird removal with multiple samples collected using a hand-held vacuum cleaner. Bird antigen levels were determined by an inhibition enzyme-linked immunoassay. In five homes the antigen declined gradually despite extensive environmental control measures, with high levels still detectable at 18 months in one home. This data suggests that high levels of bird antigen can be detected for prolonged periods of time after bird removal and environmental cleanup. The antigen may account for the persistence of disease in some patients with HP. In severe HP, the preferred therapy may be temporary relocation of the patient away from the room in which the bird was housed, in addition to corticosteroids, until the patient's environment is demonstrated to be relatively bird antigen-free.

Air Pollution↗
PubMed1988

Regulation of enzyme levels in the blood. Influence of environmental and genetic factors on enzyme clearance.

Since its discovery, lactic dehydrogenase virus (LDV) has remained unique as a model of long-term enzyme elevation due to impairment of enzyme clearance. The present study shows that mice inoculated with silica develop an increase in plasma lactate dehydrogenase (LDH) lasting for at least 6 months and that the enzyme elevation is due, at least in part, to impairment of clearance. The extent of the enzyme elevation is dependent on both the dose and route of silica administration and mice that had received both silica and LDV showed a more profound impairment of LDH clearance than mice that had received silica or LDV alone. Examination of the factors that regulate circulating enzyme levels in normal mice revealed that whereas there was no difference in resting enzyme levels among several inbred strains of mice (BALB/cAnN, NZBWF1/J,B10.D2/nSnN, and A/J mice), when mice were stressed by the administration of an enzyme load, certain inbred strains (BALB/cAnN) cleared the enzyme rapidly and others (B10.D2/nSnN) cleared the enzyme slowly. Moreover, in B10.D2/nSnN mice, enzyme clearance was age-related. When different strains of mice were infected with LDV, LDH levels were substantially higher in the circulation of slow enzyme clearers as compared to rapid enzyme clearers. It is concluded that both environmental and genetic factors influence the clearance of LDH and that impairment of enzyme clearance may be a more important factor than previously suspected in regulating enzyme levels in disease states.

Animals↗
PubMed1987

5-Aminosalicylate: oxidation by activated leukocytes and protection of cultured cells from oxidative damage.

It has been postulated that oxygen radicals may play a role in the pathogenesis of inflammatory bowel disease. If so, then a drug like 5-aminosalicylate (5-ASA), which is used to treat such diseases, might work by interacting with oxygen-derived species. We found that activated mononuclear cells and activated granulocytes, as well as the products of the Fenton reaction, transformed [14C]5-ASA to a number of metabolites, among which we have characterized salicylate and gentisate. We also found that the lethal effect on cultured Chinese hamster ovary cells of adding either superoxide radical or hydrogen peroxide, components of the respiratory burst of activated white blood cells, was diminished by the addition of 100 micrograms/ml (0.65 mM) of 5-ASA. Thus, we have demonstrated that 5-ASA was oxidized by the oxidative burst of white blood cells and that 5-ASA protected cells from damage by oxygen-derived species, two findings which may offer an explanation for the role of 5-ASA in the treatment of inflammatory bowel disease.

Aminosalicylic Acids↗
PubMed1985

Restoration of prostacyclin synthase in vascular smooth muscle cells after aspirin treatment: regulation by epidermal growth factor.

Prostacyclin is a potent vasodilator and inhibitor of platelet aggregation and plays an important role in maintenance of vascular homeostasis. Aspirin irreversibly inactivates prostacyclin synthetase by acetylating the enzyme. Recovery of the enzyme following inactivation by aspirin was studied in rat aorta smooth muscle cells in tissue culture. Confluent cultures superfused with [14C]arachidonic acid, synthesized prostacyclin (PGI2) together with prostaglandins E2, D2, and F2 alpha. Brief treatment with physiological levels of aspirin (0.2 mM) completely inactivated prostacyclin synthesis. Following aspirin removal and addition of fresh growth medium, PGI2 synthesis recovered rapidly with a T 1/2 of only 30-40 min, compared to a doubling time of 24-30 hr for the cells. Recovery of PGE2, PGD2, and PGF2a synthesis paralleled that of PGI2, confirming that cyclooxygenase rather than endoperoxide-prostacyclin isomerase was the labile component. Recovery of PGE2 synthesis after aspirin was blocked by cycloheximide but not by actinomycin D. Recovery of aspirin-inactivated cells required a non-dialyzable component present in serum. All samples tested, including fetal bovine, new-born calf, human, and guinea pig, showed the activity. Fresh serum also induced a cycloheximide-sensitive 2- to 3-fold increase in cyclooxygenase levels in resting confluent cells within 1 to 2 hr. Serum factor was also required to restore PG synthesis after aspirin-inactivation in other cells, including 3T3 mouse fibroblasts, SV40-3T3 and K-Balb 3T3 transformed mouse fibroblasts, NRK rat kidney cells, and REF-9 rat embryonic fibroblasts. The activity was thermolabile, and was completely removed from the medium by growing cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Characterization of 11-HETE and 15-HETE, together with prostacyclin, as major products of the cyclooxygenase pathway in cultured rat aorta smooth muscle cells.

Arachidonic acid is the precursor of several potent derivatives that regulate physiological functions in the cardiovascular system. Thromboxane (TXA2) and prostacyclin (PGI2) are synthesized by the cyclooxygenase enzyme. The proaggregatory and vasoconstrictive TXA2 produced by platelets is opposed in vivo by the antiaggregatory and vasodilating activity of PGI2 synthesized by blood vessels. Arachidonic acid is also converted via a 5-lipoxygenase to leukotrienes, the vasoconstrictive components of SRSA. We have shown that this latter pathway is regulated by 15-HETE, a product of the 15-lipoxygenase present in lymphocytes. Confluent cultures of rat aorta smooth muscle cells (RSM) were superfused briefly with [14C]arachidonic acid. The products were isolated and analyzed by thin-layer chromatography-radioautography, high performance liquid chromatography, and gas-liquid chromatography-mass spectrometry. Prostacyclin (PGI2) was identified as the major product both by its biological properties in a platelet aggregation assay and by the mass spectrum of its tetra-trimethylsilylether-methyl ester derivative. Minor quantities of PGE2, PGD2, and PGF2 alpha were also synthesized. Three other compounds with chromatographic properties of mono-hydroxy eicosanoic acids were also formed in major amounts. These were shown to be cyclooxygenase products since their synthesis, together with that of prostacyclin, was blocked by the cyclooxygenase inhibitors aspirin (0.2 mM) and indomethacin (10 microM). Quantities of the hydroxy-eicosanoids were isolated from large scale incubations by silicic acid chromatography. Following methylation and reduction with platinum oxide/H2, the compounds were converted to their trimethylsilylether derivatives and analyzed by gas-liquid chromatography-mass spectrometry. The compounds were identified as 11-hydroxy-5,8,12,14-eicosatetraenoic acid (11-HETE), 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE), and hydroxy-5,8,10-heptadeca-trienoic acid (HHT) by simultaneous ion monitoring of characteristic ions at M/e ratios of 287, 258, 229 for 11-HETE and 343, 314, 173 for 15-HETE, and by comparison with the mass spectra of authentic samples. Rat smooth muscle cells, prelabeled by 24-hour incubation with [14C]arachidonic acid, released large amounts of prostacyclin together with enhanced amounts of 11- and 15-HETE in response to physiological levels of thrombin (0.5-5 units/ml). These experiments demonstrate that, in addition to the thromboxane antagonist prostacyclin, vascular smooth muscle cells produce significant quantities of the leukotriene inhibitor 15-HETE via the cyclooxygenase pathway in response to physiological stimuli such as thrombin. The release of both prostacyclin and 15-HETE by vascular smooth muscle cells may thus play an important role in vascular homeostasis.

Animals↗
PubMed1980

Aspirin: an unexpected side effect on prostacyclin synthesis in cultured vascular smooth muscle cells.

Monolayer cultures of rat aorta smooth muscle cells synthesized the anti-aggregatory substance prostacyclin via the cyclooxygenase pathway from 14C-labeled arachidonic acid. The product was identified both by bioassay and by mass spectrometry. Labeled cells produced prostacyclin only when exposed to the initiator thrombin: treatment with therapeutic concentrations of aspirin (0.2 millimolar) for 30 minutes completely destroyed the cells' ability to synthesize prostacyclin. Prostacyclin synthesis from exogenous arachidonic acid recovered fully within 1 to 2 hours by a cycloheximide-sensitive process. Thrombin responsivness, which was permanently impaired in confluent nondividing cultures, recovered substantially and within 24 hours only when cells were stimulated to divide by subculturing. These results indicate that resting vascular cells can rapidly synthesize new cyclooxygenase, but that aspirin destroys additional components of the prostacyclin system which can only be replaced during cell division.

Animals↗