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Biomedical subjects

D Ochs

Publications and source records attributed to D Ochs.

At least 19 recordsLinked to original sources
PubMed2005

Triclosan inhibition of fatty acid synthesis and its effect on growth of Escherichia coli and Pseudomonas aeruginosa.

OBJECTIVES: To assess the effect of triclosan on fatty acid synthesis and to relate the inhibition of enoyl reductase to bacterial viability. METHODS: The effect of triclosan on fatty acid synthesis in a triclosan-resistant Escherichia coli and its sensitive counterpart and in Pseudomonas aeruginosa was investigated by measuring acetate incorporation into total lipid followed by analysis of fatty acid methyl esters by gas chromatography. Concurrently, the bactericidal effect of triclosan against these bacterial strains was assessed. RESULTS: Triclosan inhibited fatty acid biosynthesis in all the strains tested. However, for triclosan-resistant E. coli (MIC > 1000 mg/L) the concentration required to achieve inhibition was higher than that required for the susceptible counterpart. These concentrations did not significantly affect cell survival in any of the strains tested. CONCLUSIONS: This study shows that the inhibition of fatty acid biosynthesis by the bisphenol might be involved in its growth-inhibitory action and that other mechanisms are involved in its lethal effect. In addition, although microorganisms with a high triclosan MIC were still susceptible to the inhibitory effect of the bisphenol on fatty acid biosynthesis, a higher concentration of the compound was required. This suggested that triclosan bioavailability was different in these strains.

Escherichia coli↗
PubMed2005

Triclosan-bacteria interactions: single or multiple target sites?

AIMS: To investigate the inhibitory and lethal effects of triclosan against several micro-organisms at different stages of their phase of population growth. METHODS AND RESULTS: Triclosan minimum inhibitory concentrations against several test organisms were determined in broth and agar using standard protocols. The bisphenol effect on bacterial population growth kinetics was studied using the Bioscreen C microbial growth analyser. Finally, the efficacy of triclosan on phases of bacterial growth was determined using a standard suspension test. The duration of the lag phase for all micro-organisms tested was increased by bisphenol in a concentration-dependent manner. The population growth kinetics of the micro-organisms was also altered after biocide exposure. At higher concentrations, triclosan was bactericidal regardless of their phase of population growth, although population in stationary phase and particularly, washed suspensions, were more resilient to the lethality of triclosan. This lethal activity was concentration and contact time dependent, and in some instances, bactericidal activity of bisphenol was observed within 15 s. CONCLUSIONS: Low concentrations of triclosan affected the growth of several bacteria, while higher concentrations were bactericidal regardless of the bacterial phase of population growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Here, we presented clear evidence that the interaction of triclosan with the bacterial cell is complex and its lethality cannot be explained solely by the inhibition of metabolic pathways such as the enoyl acyl-reductase. However, the inhibition of such pathways cannot be ruled out as part of the lethal mechanism of the bisphenol at a low bactericidal concentration.

Anti-Infective Agents, Local↗
PubMed2000

Sequential cytokine therapy for pressure ulcers: clinical and mechanistic response.

OBJECTIVE: To compare the healing response of sequential topically applied cytokines to that of each cytokine alone and to a placebo in pressure ulcers, and to evaluate the molecular and cellular responses. SUMMARY BACKGROUND DATA: Because of a deficiency of cytokine growth factors in chronic wounds and the reversal of impaired healing in animal models, pressure ulcer trials have been performed with several exogenously applied growth factors. Because single-factor therapy has not been uniformly successful, combination or sequential cytokine therapy has been proposed. Laboratory data have suggested that sequential treatment with granulocyte-macrophage/colony-stimulating factor (GM-CSF)/basic fibroblast growth factor (bFGF) might augment the previously reported effect of bFGF alone. METHODS: A masked, randomized pressure ulcer trial was performed comparing sequential GM-CSF/bFGF therapy with that of each cytokine alone and with placebo during a 35-day period. The primary measure was wound volume decrease over time. Cytokine wound levels and mRNA levels were serially determined. Fibroblast-populated collagen lattices (FPCLs) were constructed from serial fibroblast biopsies. Cellular ultrastructure was evaluated by electron microscopy. Changes in ease of surgical closure and its relative cost were determined. RESULTS: Ulcers treated with cytokines had greater closure than those in placebo-treated patients. Patients treated with bFGF alone did the best, followed by the GM-CSF/bFGF group. Patients treated with GM-CSF or bFGF had higher levels of their respective cytokine after treatment. Patients with the greatest amount of healing showed higher levels of platelet-derived growth factor (PDGF) on day 10 and transforming growth factor beta (TGFbeta1) on day 36. Message for the bFGF gene was upregulated after treatment with exogenous bFGF, suggesting autoinduction of the cytokine. FPCLs did not mimic the wound responses. Ultrastructure of wound biopsies showed response to bFGF. Treatment with any of the cytokines improved the wound by allowing easier wound closure. This was most marked for the bFGF-alone treatment, with a cost savings of $9,000 to $9,200. CONCLUSIONS: Treatment with bFGF resulted in significantly greater healing than the other treatments in this trial. The clinical response appeared to be related to upregulation of the bFGF message and to increased levels of PDGF-AB, bFGF, and TGFbeta1 in the wounds and changes in ultrastructure. The resultant improvements could be correlated with cost savings.

Double-Blind Method↗
PubMed1998

Total synthesis and biological activities of (+)- and (-)-boscialin and their 1'-epimers.

Natural (-)-boscialin [(-)-1] has recently been described as one of the constituents of various medicinal plants. To obtain more material for investigations of its biological activities, we carried out the synthesis of (-)-1 and its isomers. Starting from the chiral building block 2, the key steps of the synthesis involved a regioselective reduction and a nucleophilic addition. The enantiomer of the natural product, (+)-boscialin [(+)-1], could be obtained via acid-catalyzed epimerization of hydroxyketone 4 to (+)-3. Starting the synthesis with (-)-3 led to (-)-boscialin [(-)-1] with the natural absolute configuration. In addition to (+)- and (-)-boscialin, the corresponding 1'-epimers (+)- and (-)-epiboscialin were also obtained. In vitro assays with (-)-boscialin [(-)-1] and its three stereoisomers were carried out to test for activity against microbes, parasites, and human fibroblasts. The investigations revealed activity against various microbes and against Trypanosoma brucei rhodesiense and also revealed cytotoxicity against human cancer cells.

Animals↗
PubMed1995

Large-scale preparation and biological activity of recombinant human parathyroid hormone.

Human parathyroid hormone (hPTH) has been bacterially expressed in bioreactors as cro-beta-galactosidase-hPTH fusion protein. We have developed a large-scale purification scheme that exploits the pH-dependent differential solubility of hPTH and a two-step chromatographic procedure. We demonstrate that in a number of assay systems, the recombinant material obtained by this procedure is biologically active.

Animals↗
PubMed1992

Cloning, expression, and sequencing of squalene-hopene cyclase, a key enzyme in triterpenoid metabolism.

The pentacyclic hopanoids, a class of eubacterial lipids, are synthesized by squalene-hopene cyclase and side chain-elongating enzymes. With the aid of DNA probes based on the amino-terminal sequence of purified squalene-hopene cyclase from Bacillus acidocaldarius, clones of Escherichia coli that express this enzyme in the cytoplasmic membrane were isolated. According to the DNA sequence, the cyclase contained 627 amino acids with a molecular mass of 69,473 Da. A high percentage of the amino acids were basic. No significant similarity to existing sequenced proteins was found.

Amino Acid Sequence↗
PubMed1990

Properties of purified squalene-hopene cyclase from Bacillus acidocaldarius.

The squalene-hopene cyclase from Bacillus acidocaldarius cytoplasmic membrane, was purified to homogeneity by solubilization with Triton X-100, chromatography on DEAE-cellulose, phenyl Sepharose and two gel-filtration columns. The enzyme monomer had a molecular mass of 75 kDa. The sequence of the first 23 amino acids was determined by Edman degradation. The enzyme activity was efficiently inhibited by n-alkyldimethylammonium halides with alkyl chain lengths between 12 and 18 C atoms. Inhibition was also observed with (5-hydroxycarvacryl)trimethylammonium chloride 1-piperidine carboxylate, dodecyldimethylamine N-oxide, azasqualene and farnesol. Competitive inhibition with dodecyltrimethylammonium bromide, (5-hydroxycarvacryl)trimethylammonium chloride 1-piperidine carboxylate and dodecyldimethylamine N-oxide was demonstrated by Lineweaver-Burk plots.

Amino Acid Sequence↗
PubMed1990

Silastic prosthesis plombage for right postpneumonectomy syndrome.

In rare instances, right pneumonectomy can produce progressive exertional dyspnea and reduce ventilatory reserve because of extreme mediastinal shift (right postpneumonectomy syndrome). The diagnosis can be made by bronchoscopy and computed tomography. We report a case of a 43-year-old patient in whom plombage with two Silastic breast implants produced mediastinal derotation and symptomatic relief of this syndrome.

Adenocarcinoma↗
PubMed1988

Luteal-phase support in stimulated cycles in an in vitro fertilization/embryo transfer program: progesterone versus human chorionic gonadotropin.

A study was undertaken to compare the hormonal parameters [serum concentrations of estradiol (E2), and progesterone (P) and P/E2 ratios] of patients undergoing in vitro fertilization/embryo transfer to whom either progesterone in oil or human chorionic gonadotropin (hCG) was administered as luteal support. Seventeen patients were studied in 20 cycles. In 10 randomly assigned cycles 25 mg of intramuscular progesterone in oil was administered daily from the day of embryo transfer (day +4) until day +18. In the other 10 cycles, 1500 IU of hCG was given intramuscularly on days +4, +7, +10, and +13. Even when accounting for the differences in recruitment in the two groups, the hCG-treated group had significantly higher concentrations of serum P (P less than 0.01) and E2 (P less than 0.05) during the luteal phase. The luteal P/E2 ratios were higher in the progesterone-treated group because of the lower E2 levels in that group, although the difference was not statistically significant. The ratio of the mean luteal P to the preovulatory serum E2 was significantly higher in the hCG-treated group (P less than 0.01). There were three clinical pregnancies in the hCG-treated group. We conclude that (1) higher P concentrations are achieved with hCG treatment than with progesterone treatment during the luteal phase; (2) high luteal P/E2 ratios per se may not be an important determinant of implantation; (3) progesterone production by the corpus luteum is not maximal in progesterone-treated cycles; and (4) the usefulness of hCG as a luteal support agent should be further evaluated.

Chorionic Gonadotropin↗
PubMed1988

Isolation of an antigenically "null" cell line from pig peripheral blood mononuclear cells.

A new pig cell line (A4) isolated from a primary culture of pig peripheral blood mononuclear cells was characterized. A4 was demonstrated to be morphologically, antigenically and functionally distinct from the more commonly isolated pig lymphoblastoid B cell lines (e.g. P-SC). When the A4 cell line and clones derived from it were tested against a panel of monoclonal antibodies, which define specific subpopulations of pig mononuclear cells, little or no reactivity was observed. The A4 cell line, unlike the P-SC cell line, was unable to induce a mixed lymphocyte reaction. The amount of immunoglobulin secreted by A4 cells as detected by an ELISA was reduced compared to that produced by P-SC cells. The P-SC cell lines produced an IL-1-like factor, whereas no IL-1-like activity was found in the A4 supernatant. The A4 cell line appeared to be a null cell in respect to the P-SC cell line properties; only the slight amount of immunoglobulin produced suggested that the A4 cell line is of the B cell lineage. An association of viral particles with cells of the A4 morphology and null antigenic characteristics was observed and may provide an explanation for the reduced B cell properties of A4 cells.

Animals↗
PubMed1988

Cellular defense of the avian respiratory system: influx and nonopsonic phagocytosis by respiratory phagocytes activated by Pasteurella multocida.

Poultry have a very limited number of resident macrophages in the normal steady-state respiratory tract. Thus, poultry must rely heavily on active migration of phagocytic cells to the lungs and air sacs in defending against respiratory pathogens. Intratracheal administration of a live, apathogenic Pasteurella multocida vaccine (Choloral; Clemson University strain) increased the number of avian respiratory phagocytes (ARP; obtained by lavage of lungs and air sacs) within 24 h by 3 orders of magnitude compared with the number of ARP obtained from mock-inoculated controls and from nonreacting chickens. Chickens yielding a high number of ARP did not show any sign of respiratory disease. Flow cytometric analysis of ARP that were exposed to 20 nonopsonized fluorescent microspheres per ARP for 30 min at 37 degrees C demonstrated a fivefold increase in the percentage of actively phagocytic cells in the ARP populations of stimulated chickens compared with the percentage of phagocytic ARP for mock-inoculated control birds. The phagocytic capacity (relative number of engulfed microspheres) of ARP from stimulated birds doubled during the same time. The flow cytometric observations were confirmed by fluorescence microscopy. These results indicate that activation by avirulent replicating agents of phagocytic cells of chicken to migrate to the respiratory tract may be a means of defending poultry against air sacculitis and pneumonia.

Animals↗
PubMed1987

Patterns of increase in serum estradiol in response to ovarian stimulation and their relationship to oocyte fertilization and cleavage in vitro.

The in vitro fertilization and cleavage rates of oocytes obtained from patients exhibiting two different patterns of increase in serial serum concentrations of estradiol (E2) in response to ovarian stimulation were compared. Forty-two cycles (from 38 stimulated patients) were evaluated because they fulfilled requirements from two pre-defined patterns of E2 response to ovarian stimulation. In 16 cycles, serial serum E2 concentrations followed a "plateau" pattern (group A), viz., the rate of increase in the serum concentration of E2 decreased prior to the administration of human chorionic gonadotropin (hCG). In 26 cycles, serial serum E2 concentrations followed a "leap" pattern (group B), in which the rate of increase in serum concentrations of E2 increased progressively up to and including the day of hCG administration. There was no significant difference in the fertilization rate of oocytes obtained from patients exhibiting either pattern A or pattern B (78 versus 74%) but the cleavage rate was significantly higher in ova obtained from patients who exhibited pattern A rather than pattern B (72 vs 50%; P less than or equal to 0.01). In addition, embryos resulting from fertilized ova obtained from women in group A were of better quality morphologically than those obtained from women in group B (mean embryo grades, 3.9 vs 3.2; P less than or equal to 0.005). We conclude that cycles in which serial serum concentrations of E2 follow pattern A in response to stimulation give rise to oocytes that, when fertilized, yield higher cleavage rates and better-quality embryos than oocytes obtained from women in whom serial serum E2 concentrations follow pattern B.(ABSTRACT TRUNCATED AT 250 WORDS)

Chorionic Gonadotropin↗
PubMed1986

Intermediate filament proteins in human sperm heads.

Monoclonal antibodies made against human sperm cells have been characterized with regard to binding patterns and molecular coordinates of the recognized antigens. Antibodies T5 and T6 gave uniform binding to the acrosomal cap in an intact cell, and decreased to equatorial segment binding in an 'acrosome-reacted' cell. Monoclonal antibody T15 gave the reverse: equatorial segment binding in intact cells and uniform acrosomal cap binding in reacted cells. From staining patterns on cultured cell lines, determination of molecular coordinates, immunoblots, and partial peptide analysis, we have determined that T15 is directed against the cytoskeletal protein, vimentin, while T5 and T6 recognize a keratin-like protein which may be unique to sperm cells. This is the first immunological and biochemical study to analyse both types of intermediate filament proteins in human sperm cells.

Antibodies, Monoclonal↗
PubMed1986

Patterns of estradiol response in patients with endogenous gonadotropin surges during follicular recruitment in an in vitro fertilization and embryo transfer program.

This report is an analysis of 16 cycles in 15 patients stimulated with human menopausal gonadotropin and clomiphene citrate for the purpose of follicular recruitment in an in vitro fertilization program, all of which resulted in endogenous luteinizing hormone (LH) surges. A study of the pattern of estradiol (E2) response to stimulation revealed two groups of cycles, designated "leap" pattern (9 cycles) and "plateau" pattern (7 cycles), the rate of rise of E2 increasing or decreasing, respectively, as the time of the LH surge was approached. There were no significant differences between these groups of cycles in the peak E2 level attained or the number of follicles greater than or equal to 12 mm on the day of peak E2. In the plateau, but not in the leap pattern cycles, a significant correlation (r = 0.958) was found between the number of follicles greater than or equal to 12 mm and the peak E2. We tentatively conclude that "plateau" pattern cycles reflect relatively synchronous follicular recruitment; the greater the number of follicles recruited, the higher the E2 level attained, increased amounts of inhibin-like substances being available to restrain the LH surge; "leap" pattern cycles reflect asynchronous follicular recruitment.

Clomiphene↗
PubMed1986

Undetected ovulation in in vitro fertilization-embryo transfer patients.

A retrospective evaluation was done of 102 consecutive in in vitro fertilization-embryo transfer (IVF-ET) treatment cycles that culminated in surgical intervention for oocyte pickup. In 35% of these patients, a disparity was noted in the number of mature follicles present on the day of human chorionic gonadotropin administration, compared with the day of surgery. This suggests the occurrence of undetected ovulation. An endogenous luteinizing hormone (LH) surge was detected in 14 of these patients. Another cohort showed evidence of early luteinization without a detected endogenous LH surge. Finally, a group without early luteinization was defined. Possible explanations for these outcomes and the implications for success of IVF-ET are discussed.

Embryo Transfer↗
PubMed1985

Actin in ejaculated human sperm cells.

Previous studies have identified an "actin-like" protein in human sperm by indirect immunofluorescence microscopy with various probes, but no real biochemical confirmation of actin was made. In this study, two-dimensional (2-D) gels of Nonidet P-40 (NP-40) extracts of purified human sperm cells revealed a protein with appropriate pI and molecular weight coordinates for actin. When excised from a 2-D gel, cleaved with N-chlorosuccinimide, and separated on a sodium dodecyl sulfate slab gel, this putative actin showed a cleavage pattern identical to those from known actin. Furthermore, when sperm were immediately purified from whole semen and extracted with 0.3% NP-40, actin was detected almost entirely in the soluble fraction, indicative of unpolymerized actin. Conclusions from these experiments support those implied by direct immunofluorescence microscopy: actin is present in human sperm and appears to be mainly unpolymerized.

Actins↗
PubMed1983

Protein contaminants of sodium dodecyl sulfate-polyacrylamide gels.

Many artifacts and confusing results have arisen following the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and highly sensitive detection methods such as silver staining, in vitro iodination, and immunological reactions ("Western blotting"). Investigations into many areas of biology, from proteins tightly bound to DNA to common antigenic determinants of intermediate filaments, may have been affected by this confusion. Some who have suspected contamination believed 2-mercaptoethanol to be the source, but data in this report show that the contaminating proteins are skin proteins, especially keratins ranging from 54 to 57 kDa and 65 to 68 kDa.

Acrylic Resins↗