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Biomedical subjects

R Moeller

Publications and source records attributed to R Moeller.

At least 19 recordsLinked to original sources
PubMed2006

A method for extracting RNA from dormant and germinating Bacillus subtilis strain 168 endospores.

RNA was extracted from dormant and germinating Bacillus subtilis 168 spores (intact spores and chemically decoated spores) by using rapid rupture followed by acid-phenol extraction. Spore germination progress was monitored by assaying colony forming ability before and after heat shock and by reading the optical density at 600 nm. The purity, yield, and composition of the extracted RNA were determined spectrophotometrically from the ratio of absorption at 260 nm to that at 280 nm; in a 2100 BioAnalyzer, giving the RNA yield/10(8) spores or cells and the distribution pattern of rRNA components. The method reported here for the extraction of RNA from dormant spores, as well as during different phases of germination and outgrowth, has proven to be fast, efficient and simple to handle. RNA of a high purity was obtained from dormant spores and during all phases of germination and growth. There was a significant increase in RNA yield during the transition from dormant spores to germination and subsequent outgrowth. Chemically decoated spores were retarded in germination and outgrowth compared with intact spores, and less RNA was extracted; however, the differences were not significant. This method for RNA isolation of dormant, germinating, and outgrowing bacterial endospores is a valuable prerequisite for gene expression studies, especially in studies on the responses of spores to hostile environmental conditions.

Bacillus subtilis↗
PubMed2005

Chip-based electrical detection of DNA.

A variety of methods have been developed for the detection of the binding of the complementary strand of DNA to a gene chip using electrical rather than the established optical signal techniques. Chip-based DNA sensors offer sensitivity, specificity, parallelisation and miniaturisation for the detection of selected DNA sequences or mutated genes associated with human diseases. Problems associated with the established fluorescence-based optical detection technique include the high equipment costs and the need to use sophisticated numerical algorithms to interpret the data. These problems generally limit its use to research laboratories and make it hard to adapt this detection scheme for on-site or point-of-care use. An electrical readout might be a solution to these problems. A review of a number of different approaches to achieve an electrical readout for a DNA chip is presented. The review covers various methods that are based on the use of metal nanoparticles as labels and also electrochemical methods that use polymer-modified electrodes, DNA-specific redox reporters, and DNA-mediated charge transport techniques.

DNA↗
PubMed2004

Neonatal-mouse infectivity of intact Cryptosporidium parvum oocysts isolated after optimized in vitro excystation.

We reexamined the finding of Neumann et al. that intact Cryptosporidium parvum oocysts obtained after in vitro excystation were infectious for neonatal CD-1 mice. We used both established excystation protocols and our own protocol that maximized excystation. Although intact oocysts isolated after any of three protocols were infectious for neonatal CD-1 mice, the infectivity of intact oocysts isolated with our optimized excystation protocol was significantly lower than the infectivity of intact oocysts isolated after established protocols or from fresh oocysts. Excystation should not be considered a valid measure of C. parvum viability, given that it is biologically implausible for oocysts to be nonviable and yet infectious.

Animals↗
PubMed2003

Hepatitis associated with a Sarcocystis canis-like protozoan in a Hawaiian monk seal (Monachus schauinslandi).

A Hawaiian monk seal (Monachus schauinslandi) died in captivity at the National Marine Fisheries Service, Kewalo Basin Facility in Honolulu, Hawaii. The animal was icteric, and the liver was friable. Microscopic lesions were detected in the colon and liver. Colonic lesions included multifocal, necrohemorrhagic colitis associated with gram-negative bacilli. The liver lesions included random hepatic necrosis and cholestasis. Asexual stages of a Sarcocystis canis-like apicomplexan were detected in hepatocytes. The parasite divided by endopolygeny. Merozoites occasionally formed rosettes around a central residual body. Ultrastructurally, merozoites lacked rhoptries. This is the first report of S. canis infection in M. schauinslandi, which is an endangered pinniped in U.S. waters.

Animals↗
PubMed2001

Hormonal response of female goats to active immunization against a recombinant human inhibin alpha-subunit, and establishment of an enzyme-linked immunosorbent assay for caprine follicle-stimulating hormone.

The effect of selective immunosuppression of endogenous inhibin in goats on FSH, LH, progesterone and estradiol-17beta profiles was studied during the breeding and nonbreeding seasons. Eighteen adult female Boer goats were immunized against the recombinant human inhibin alpha-subunit (hINH-alpha). With the exception of estradiol, which was determined by radio-immunoassay (RIA), all plasma hormone concentrations were determined by ELISA. The ELISA for FSH presented in this paper was established in the authors' laboratory, based on an existing RIA. Mean basal concentrations of FSH were not affected by immunosuppression of endogenous inhibin, nor was there a difference in the amplitude of the pre-ovulatory FSH surge. Immunization against inhibin appears to eliminate the slight secondary rise of FSH occurring 12-20 h after the major surge associated with ovulation. The LH profiles of the immunized goats were characterized by lower basal concentrations both before and after the pre-ovulatory LH surge which itself was reduced by 50% in immunized does. By contrast, concentrations of circulating estradiol were significantly elevated after inhibin-immunization. Progesterone profiles were not affected. Extending immunization into the anoestrous season by a booster injection of hINH-alpha, implicating oestrus induction with a progestagen and eCG, produced no discernible differences in FSH and LH profiles in comparison with nonimmunized control goats. The findings suggest that in goats, paracrine factors may play a more significant role in controlling follicular activity than a feedback mechanism acting via the pituitary.

Animals↗
PubMed1998

Sensitivity of cross-reacting antihuman antibodies in formalin-fixed porcine skin: including antibodies to proliferation antigens and cytokeratins with specificity in the skin.

Although no animal is a perfect skin model for the study of toxicological and therapeutic agents, structurally the pig may be superior to even non-human primates. Because our work involves effects of toxicological and therapeutic agents on the skin, we wanted to identify stains which may prove useful as well as determine cross-reactivity of some newer antihuman antibodies. We performed a battery of formalin-fixed skin from weanling pigs and minipigs. The battery of antibodies included LCA, CD3, OPD-4, CD34, UCHL-1, L-26, KP-1, MAC-387, Factor XIIIa, Leu-7, S-100 protein, HMB-45, GFAP, synaptophysin, neurofilament protein, ubiquitin, vimentin, type IV collagen, laminin, fibronectin, Factor VIII related antigen, Desmin-M, smooth muscle actin, cytokeratin 7, cytokeratin 20, AEI/AE3, CAM 5.2, EMA, GCDFP, Ki-67, and PCNA. Immunohistochemical stains for CD3, Leu-7, S-100 protein, type IV collagen, laminin, Factor VIII related antigen, GFAP, synaptophysin, neurofilament protein, ubiquitin, smooth muscle actin, vimentin, Desmin-M, cytokeratin 7, cytokeratin 20, AE1/AE3, CAM 5.2, Ki-67 and PCNA showed consistent cross-reactivity. In formalin-fixed tissue, only antibodies to lymphoreticular cells showed poor cross-reactivity. A high percentage of the remaining antibodies did show good cross-reactivity but with some interesting similarities and differences in specificity.

Animals↗
PubMed1998

Histopathologic and immunohistochemical features in human skin after exposure to nitrogen and sulfur mustard.

N-methyl-2,2'-dichlorodiethylamine (HN2)is a topical chemotherapeutic agent used as therapy for cutaneous T-cell lymphomas (CTCL). Di(2-chloroethyl)sulfide (SM), and less often HN2, have been used as chemical weapons, with the skin being a principle target. The mechanisms by which these chemicals produce their therapeutic and toxic effects in skin, however, are not clearly defined. We exposed human skin explants to two doses of HN2 and SM. At 18 hours after exposure, histopathologic features were compared. In addition, immunohistochemical markers to basement membrane proteins were used to evaluate the effects of both chemicals on the basement membrane zone. Gross vesication was not seen. Pyknotic nuclei with or without dyskeratotic changes within epidermal keratinocytes were present at both doses. These changes varied more between skin specimens than they did between doses. Ballooning degeneration was more marked after SM exposures. Diffuse dermal-epidermal separation was present only at high-dose exposures and did not appear to correlate with the degree of changes locally in the overlying epidermis. Antibodies to laminin-5 showed decreased immunoreactivity after exposure to HN2 and SM. Immunoreactivity for laminin- was decreased to a lesser extent, and immunoreactivity for collagen IV and VII was unchanged. HN2 and SM produce similar histopathologic and immunohistochemical features after cutaneous exposure. These features suggest that part of mechanism of action of HN2 and SM is a direct effect on the basement membrane zone. Understanding the effects of HN2 and SM separate from their effect on DNA may be important in designing therapies and in advancing our understanding of the pathophysiologic changes induced by these chemicals when delivered topically.

Autoantigens↗
PubMed1996

Neural networks as a tool for compact representation of ab initio molecular potential energy surfaces.

Ab initio quantum chemical calculations of molecular properties such as, e.g., torsional potential energies, require massive computational effort even for moderately sized molecules, if basis sets with a reasonable quality are employed. Using ab initio data on conformational properties of the cofactor (6R,1'R,2'S)-5,6,7,8-tetrahydrobiopterin, we demonstrate that error backpropagation networks can be established that efficiently approximate complicated functional relationships such as torsional potential energy surfaces of a flexible molecule. Our pilot simulations suggest that properly trained neural networks might provide an extremely compact storage medium for quantum chemically obtained information. Moreover, they are outstandingly comfortable tools when it comes to making use of the stored information. One possible application is demonstrated, namely, computation of relaxed torsional energy surfaces.

Biopterins↗
PubMed1989

[Clinical features of malignant hyperthermia crisis].

Malignant hyperthermia (MH) is a pharmacogenetic disorder. It is classically described as a hypermetabolic state triggered by halogenated anaesthetics and/or depolarizing muscle relaxants. In fact, since Denborough and Lovel's case, it has been shown that MH has a great number of clinical forms. The overwhelming picture of muscular hypercatabolism with fulminating hyperthermia and generalized rigidity is becoming rare. A better knowledge of the first symptoms explains in part the better prognosis: masseter spasm after suxamethonium, an increase in expired CO2 concentration, unexplained tachycardia, ventricular arrhythmias. The use of dantrolene reduced the mortality of MH. The different types of clinical manifestations are due to genetic differences, the concentration of the anaesthetic agent, and the length of time of exposure to the drug. The severity of the episode is linked to environmental factors such as stress, physical exercise, ambient temperature, concomitant use of other drugs. Masseter spasm after suxamethonium is specific for MH, but not pathognomonic. It occurs in 1% of cases in children when using halothane with suxamethonium. However, in those patients who displayed such a spasm, more than 50% had a positive contracture test. Masseter spasm is often associated with severe rhabdomyolysis in patients with muscle dystrophy, especially Duchenne's dystrophy. In the latter case, major cardiac problems may occur at the time of anaesthetic induction. Even if there are no other signs of MH, all patients who have had a masseter spasm must be considered as open to doubt, and should be further explored. MH is often difficult to diagnose in medium severity types.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

[Contracture test with ionophore A 23187 for the diagnosis of malignant hyperthermia].

The results are reported of the contracture test obtained by using the calcium ionophore A 23187 (Calcimycin) in two patients, the son (A) and the mother (B). The past history of patient A revealed the occurrence of an impending malignant hyperthermia crisis during induction of anaesthesia in 1975. The A 23187 contracture test confirmed the presence of the malignant hyperthermia trait in patient A, whose muscle biopsy had been submitted to the caffeine contracture test, according to Ellis' technique, and found to be positive in the presence of 1 mmol of caffeine in the tissue bath; the contracture test could not be completed with a halothane contracture test, due to the impaired viability of the muscle fibres obtained. On the reverse, the mother (patient B) was found to be negative to the tests applied: the caffeine contracture test, the halothane contracture test and the contracture test performed with the calcium ionophore A 23187. It is suggested the A 23187 contracture test be added to the contracture tests as defined by the European Malignant Hyperpyrexia Group. This test could be of great help in identifying the percentage of relatives of MHS ("malignant hyperthermia susceptible") patients found to be MHE ("malignant hyperthermia equivocal").

Adolescent↗
PubMed1985

[Reassessment of the respective risks of anaphylaxis and histamine liberation with anesthetic substances].

A search of the French and English language literature of the last 20 years (1964-1984) yielded 975 cases of immediate anaphylactoid reactions due to anaesthetic drugs given parenterally. The accident mechanism was confirmed in only half the patients, and nearly always at a later date. The immunoallergological tests most often used in the diagnostic process were skin tests and Prausnitz-Küstner tests. Although all drugs could be responsible for an anaphylactic reaction, the greatest number of cases was due to muscle relaxants (51%) and hypnotic drugs (42.3%). The signs most often described were cutaneous, cardiovascular, respiratory and occasionally gastro-intestinal. Whilst hypnotic drugs were responsible for cutaneous signs, muscle relaxants gave cardiovascular signs. A past history of drug allergy was found in 37% of cases, and atopy in 38%; virtually all patients had already had one or more anaesthetics.

Anaphylaxis↗
PubMed1982

Adverse reactions to intravenous agents in anaesthesia in France.

One hundred severe peranesthetic accidents occurring in hospitals in the eastern part of France were tested between 1975 and 1980 at the Immunological Unit of the University Hospital in Nancy. Tests were carried out "a posteriori"; mean time: three weeks after the accident (extremes: one week to one year). A second battery of tests was carried out in 35%, and a third one in 8% of the patients. Anaphylaxis was differentiated from anaphylactoid reactions be means of the tests. Responsible drugs were determined by intradermal testing, by the human basophil degranulation test and P.K. tests. Predisposing factors were studied: atopy (IgE dosage), increase of histamine release (intradermal testing with 48/80), abnormal receptivity to histamine (intradermal histamine), spasmophilia (electromyography recordings). The results show that 42 accidents were due to true anaphylaxis (one of them due to IgG); 48% of the reported accidents were due to succinylcholine. Some of the predisposing factors, in the tested population, are found in a higher proportion than in the French population as a whole; atopy, hypersensitivity to histamine, previous drug allergy, spasmophilia.

Adjuvants, Anesthesia↗
PubMed1981

Anaphylaxis due to succinylcholine. Immunoallergological study of thirteen cases.

The antigen non-specific release of histamine by synthetic neuromuscular blocking agents is well known, though our review of thirty-two cases reported in the literature of anaphylactoid reactions to succinylcholine, shows that there is insufficient evidence to determine whether the signs are due to anaphylactic or to anaphylactoid reactions. We have examined thirteen cases in whom evidence of anaphylactic sensitization was examined by direct skin tests (in eleven cases) Prausnitz--Küstner tests (in five), rabbit basophil degranulation, Shelley test (in twelve) and human basophil degranulation (in seven). These tests were done on two to four occasions, and the optimal period for the first test ascertained to be 6 to 12 weeks after the episode. All eleven patients examined by direct skin tests showed evidence of anaphylactic sensitivity, and in three of five cases the sensitivity could be transferred by the Prausnitz--Küstner procedure. In one of these P--K tests there was evidence of both IgE and of IgG S-TS antibodies (heat-stable antibody conferring sensitivity for 2 hr). Particular susceptibilities to adverse reactions of this drug appear to be prior drug allergy (in 50% of cases), several previous anaesthetics, and atopy.

Adolescent↗