Biomedical subjects

M Pfeffer

Publications and source records attributed to M Pfeffer.

At least 55 records · Page 3Linked to original sources

PubMed1998

Two-year time course and significance of neurohumoral activation in the Survival and Ventricular Enlargement (SAVE) Study.

AIMS: To describe the temporal evolution of neurohumoral activation in survivors of myocardial infarction with left ventricular dysfunction who are initially asymptomatic and to relate this to prognosis. METHODS AND RESULTS: Patients in the neurohumoral substudy (n = 534) of the Survival and Ventricular Enlargement (SAVE) study had their neurohormones measured at baseline, 3, 12 and 24 months post-infarction, were followed 38 +/- 7 months and had these values related to prognosis. All patients had a left ventricular ejection fraction < or = 40% early post-infarction. Atrial natriuretic peptide, aldosterone, norepinephrine and plasma renin activity decreased progressively over time. Patients with events had a persistent increase in these neurohormones with those dying within the first 24 months of follow-up having the greatest increase. Treatment with captopril affected only plasma renin activity (increase) and aldosterone (decrease). For patients who remained asymptomatic for the first 3 months post-infarction (n = 471), by multivariate analyses (all neurohormones together with non-neurohumoral risk factors), 3-month plasma atrial natriuretic peptide and aldosterone were the most closely related to the development of severe heart failure or to the combined end-points (cardiovascular death, myocardial infarction, or severe heart failure). No neurohormone was related to recurrent myocardial infarction or to cardiovascular mortality. When the last neurohormone measured prior to an event was considered along with non-neurohumoral risk factors (adjusted univariate), atrial natriuretic peptide, aldosterone, norepinephrine and epinephrine were associated with prognosis indicating that a time-dependent analysis identified a closer relationship between neurohormones and events than that identified by 3-month values. However, by multivariate analyses atrial natriuretic peptide was the only neurohormone associated with an event, being associated with the development of severe heart failure (P < 0.001) and the combined end-points (P = 0.022). However, when neurohormones were considered as binary variables, activated or non-activated (defined as > 1.96 SD above the mean of age-matched controls), an association between activation of norepinephrine prior to recurrent myocardial infarction (P < 0.001) and combined end-points (P < 0.01) and between activation of aldosterone and severe heart failure (P < 0.05) was identified. CONCLUSIONS: Neurohumoral activation decreases progressively post-infarction, but only in patients with a good prognosis. In patients with a left ventricular ejection fraction < or = 40% and asymptomatic post-infarction plasma atrial natriuretic peptide at 3 months, aldosterone levels appeared to be the neurohormones most closely associated with prognosis. Increased levels of atrial natriuretic peptide, aldosterone and norepinephrine appear to be temporally most closely associated with events.

Aldosterone↗

PubMed1998

Rhythmic variation in beta1-adrenergic receptor mRNA levels in the rat pineal gland: circadian and developmental regulation.

In the rat pineal gland noradrenaline is released in large quantities from sympathetic nerve endings at the onset of darkness, thereby driving rhythmic melatonin synthesis with elevated levels at night-time. Upon release, noradrenaline interacts with postsynaptic beta1-adrenergic receptors to activate the cyclic AMP signalling pathway. Well characterized third messengers of this signalling cascade affect cyclic AMP-inducible genes that are crucially involved in initiation, maintenance and termination of hormone production. Among these third messengers are CREB (cyclic AMP responsive element binding protein) as an activating and ICER (inducible cyclic AMP early repressor) as an inhibitory transcription factor. Because a cyclic AMP-inducible promoter element is present on the beta1-adrenergic receptor gene, the expression of the receptor itself may be under control of the cyclic AMP-signalling pathway. By in situ hybridization, Northern blot analysis and RT-PCR we demonstrate a day/night rhythm in beta1-adrenergic receptor mRNA in the rat pineal gland with elevated levels during the dark period. As this rhythm persists, under constant darkness but is abolished upon removal of the sympathetic innervation, it is truly circadian. A marked day/night difference in the levels of beta1-adrenergic receptor mRNA becomes evident only after postnatal day 10, coinciding with the appearance of a functional cyclic AMP signalling pathway in the rat pineal gland. Furthermore, targeting ICER expression by transfection of pinealocytes with an antisense ICER construct, clearly indicates that the levels of the beta1-adrenergic receptor mRNA are regulated by the cyclic AMP-signalling pathway in a feedback mechanism.

Animals↗

PubMed1998

Nucleotide sequences of the 26S mRNAs of the viruses defining the Venezuelan equine encephalitis antigenic complex.

Genetic relationships among viruses defining the Venezuelan equine encephalitis (VEE) virus antigenic complex were determined by analyzing the 3'-terminal 561 nucleotides of the nonstructural protein 4 gene and the entire 26S RNA region of the genome. New sequence information is reported for VEE 78V-3531 (VEE subtype-variety IF), Mucambo (IIIA), Tonate (IIIB), 71D-1252 (IIIC), Pixuna (IV), Cabassou (V), and AG80-663 (VI) viruses. The results reported here and by previous investigators largely support the current classification scheme of these viruses, while clearly identifying Everglades (II) as a subtype I virus. A genetic relationship between 78V-3531 (IF) and AG80-663 (VI) viruses contradicted previous serologic results. Mutations near the amino terminus of the E2 envelope proteins of Pixuna and AG80-663 viruses probably account for the previously reported low reactivity of the protective monoclonal antibody 1A2B-10 with these two viruses. Variations in the distribution of potential glycosylation sites in the E2 glycoprotein are discussed.

Amino Acid Sequence↗

PubMed1997

Additive beneficial effects of beta-blockers to angiotensin-converting enzyme inhibitors in the Survival and Ventricular Enlargement (SAVE) Study. SAVE Investigators.

OBJECTIVES: This study assessed whether treatment with a beta-adrenergic blocking agent in addition to the use of the angiotensin-converting enzyme (ACE) inhibitor captopril decreases cardiovascular mortality and morbidity in patients with asymptomatic left ventricular dysfunction after myocardial infarction (MI) and whether the presence of neurohumoral activation at the time of hospital discharge predicts the effects of beta-blocker treatment in these patients. BACKGROUND: Both beta-blockers and ACE inhibitors have been shown to have beneficial effects in patients with left ventricular dysfunction but no overt heart failure after MI. These patients often have persistent neurohumoral activation at the time of hospital discharge, and one would expect that patients with activation of the sympathetic nervous system derive the most benefit from treatment with beta-blockers. However, beta-blockers are underutilized in this high risk group of patients, and it is unknown whether their beneficial effects are additive to those of ACE inhibitors. METHODS: We performed a retrospective analysis of data from the Survival and Ventricular Enlargement (SAVE) study and its neurohumoral substudy. The relations between beta-blocker use at the time of randomization and neurohumoral activation and the subsequent development of cardiovascular events were analyzed by use of Cox proportional hazards models controlling for covariates. RESULTS: After adjustment for baseline imbalances, beta-blocker use was associated with a significant reduction in risk of cardiovascular death (30%, 95% confidence interval [CI] 12% to 44%) and development of heart failure (21%, 95% CI 3% to 36%), but the reduction in recurrent MI (11%, 95% CI 13% to 31%) was not significant. These reductions were independent of the use of captopril. Beta-blockers were not found to have a greater effect in patients with neurohumoral activation at the time of hospital discharge. CONCLUSIONS: The beneficial effects of beta-blocker use at the time of hospital discharge in patients with asymptomatic left ventricular dysfunction after MI appear to be additive to those of captopril and other interventions known to improve prognosis. Neurohumoral activation at the time of hospital discharge fails to identify those patients who will derive the greatest benefit from treatment with beta-blockers.

Adrenergic beta-Antagonists↗

PubMed1997

Specific detection of mousepox virus by polymerase chain reaction.

Polymerase chain reaction was applied to the rapid identification and detection of mousepox virus. This was accomplished by selection of primers targeting the A-type inclusion body protein gene. By investigating 20 strains belonging to five different species of the genus Orthopoxvirus, amplification was achieved only with the seven mousepox virus strains examined. The size of the resulting DNA fragment accounted for 116 base pairs and contained a recognition site for the restriction enzyme HindII, thus confirming its viral origin. Amplification of mousepox virus specific sequences was also possible from infected mouse lung tissue and serum.

Animals↗

PubMed1997

Genus-specific detection of alphaviruses by a semi-nested reverse transcription-polymerase chain reaction.

A reverse transcription-polymerase chain reaction (RT-PCR) was developed for the genus-specific detection of alphaviruses. Based on the available published sequences, degenerate primers were designed to ensure hybridization to a conserved region within the nonstructural protein 1 gene of all alphavirus species. The expected 434-basepair (bp) cDNA fragment was amplified from all 27 alphavirus species by using RNA extracted from 200 microl of infected cell culture supernatant. In addition, eight strains of Venezuelan equine encephalitis (VEE) virus and 10 strains of Sindbis virus were amplified. The viral origin of the amplicons was confirmed by restriction enzyme analysis and comparison with the expected cleavage pattern based on published sequence data. The PCR products of alphavirus species with thus far unknown nucleotide composition were sequenced. About 120 nucleotides downstream of the forward primer, a region showing sufficient homology for the design of another forward primer was found and used in a semi-nested PCR. The expected 310-bp semi-nested fragment was demonstrated for all viruses investigated. The sensitivity of the RT-PCR was about 1,200 plaque-forming units (PFU) for VEE virus reference strain Trinidad donkey. The detection limit after the semi-nested PCR was 1.2 PFU. The sensitivity was not hampered by the presence of human serum, thus making this test suitable for an application in viremic individuals. Chikungunya virus RNA was amplified from infected mouse brain tissue by the described RT-PCR assay. Our data suggest that the semi-nested RT-PCR may be applied as a highly sensitive alternative to virus isolation in the rapid screening and diagnosis of alphavirus infections, including post-mortem diagnosis. Phylogenetic analysis of the amplicon sequence data identified six genotypes within the Alphavirus genus.

Alphavirus↗

PubMed1996

Light-induced expression of transcription factor ICER (inducible cAMP early repressor) in rat suprachiasmatic nucleus is phase-restricted.

The mammalian hypothalamic suprachiasmatic nucleus (SCN) harbors an intrinsic circadian oscillator driving a variety of endogenous rhythms. SCN activity is entrained to environmental lighting conditions by photic information from the retina. Light-induced phase shifts involve cAMP and Ca2+ as second messengers and are linked to transcriptional and translational processes. Using in situ hybridization with a cDNA fragment of the cAMP responsive element modulator (CREM) isoform inducible cAMP early repressor (ICER) we demonstrate a light-induced upregulation of CREM mRNA in rat SCN during the second half of the night. Notably, ICER is the only member of the CREM family which is transcriptionally inducible. We suggest that a stimulus-induced upregulation of ICER expression can inhibit cAMP-inducible genes in rat SCN via its trans-repressing potency.

Animals↗

PubMed1996

Comparison of camelpox viruses isolated in Dubai.

Between October 1993 and March 1994, outbreaks of pox-like exanthemas were observed in several camel raising farms in Dubai. Scabs from twenty camels with either local or generalized lesions were examined, seven of them had previously been vaccinated with a modified live camelpox virus vaccine. Inspection of scabs by electron microscopy confirmed an infection with orthopox viruses (OPV) in 10 animals and with parapox virus in one camel. Investigation of the scabs by polymerase chain reaction and dot blot assay revealed the presence of OPV in 15 or 13 samples, respectively. OPV could be isolated in cell culture in 14 cases. Restriction enzyme profiles characterized all isolates as camelpox virus. Their DNA patterns were virtually identical displaying only slight variations in the terminal fragments. In contrast, the vaccine strain showed a distinct restriction enzyme profile, indicating that it was not involved in the infections.

Animals↗

PubMed1995

Magnetization transfer by simple sequences of rectangular pulses.

On-resonant radio frequency (RF) sequences composed of a train of short rectangular pulses of the same kind were optimized in order to obtain selective saturation of protons with short transverse relaxation times for magnetization transfer purposes. It is demonstrated that the sequences regarded allow a good adaptation to different requirements for magnetization transfer examinations on whole-body imagers. The sequences presented here provide relatively strong saturation of protons with very short transverse relaxation times T2 approximately less than 50 microseconds, whereas signals from protons with long T2 to be recorded are hardly influenced in a broad frequency range. The sequences are especially advantageous for applications in pulse files with limited numbers of support points.

Magnetic Resonance Imaging↗

PubMed1995

Applications of DNA amplification techniques in veterinary diagnostics.

An overview of the principles of the polymerase chain reaction, ligase chain reaction, self-sustained sequence replication and Q beta replicase is given. The application of these methods for the diagnosis of veterinary infectious and hereditary diseases as well as for other diagnostic purposes is discussed and comprehensive tables of reported assays are provided. Specific areas where these DNA-based amplification methods provide substantial advantages over traditional approaches are also highlighted. With regard to PCR-based assays for the detection of viral pathogens, this article is an update of a previous review by Belák and Ballagi-Pordány (1993).

Animals↗

PubMed1994

Disposition kinetics of buspirone in patients with renal or hepatic impairment after administration of single and multiple doses.

The single dose and steady-state pharmacokinetics of buspirone and its metabolite 1-pyrimidinyl piperazine (1-PP) have been evaluated in normal volunteers and patients with renal or hepatic impairment, using a parallel group design, with assignment of patients to study group on the basis of the degree of renal (mild, moderate, severe) or hepatic (compensated or decompensated) impairment. Each healthy volunteer or patient received a single dose of 10 mg buspirone on Day 1 of the study, and starting 36 h after the first dose, healthy volunteers and patients received 10 mg doses of buspirone every 12 hours for 9 days. On the morning of Day 10 they received the last dose. Serial blood samples were collected on Days 1, 5 and 10 and plasma was analysed for buspirone and 1-PP. The plasma concentrations of buspirone and 1-PP were highly variable regardless of the renal or hepatic function. The peak concentrations (Cmax) and area under the curves (AUC) of buspirone and 1-PP on Days D5 and 10 were higher than on Day D1. The trough levels (Cmin) and AUCs (D5 and 10) of buspirone and 1-PP indicated, that, regardless of renal or hepatic function, steady state was reached after 3 to 5 days of dosing. At steady-state, patients with renal or hepatic impairment had significantly higher Cmax and AUC values of buspirone than in normal volunteers. However, the intensity and frequency of adverse experiences in patients with renal or hepatic impairment were not significantly different from those observed in normal volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Characterization of the gene encoding the A-type inclusion body protein of mousepox virus.

The gene of the mousepox virus strain MP-1 coding for the protein of A-type inclusions was identified and sequenced. The gene maps in the HindIII-A fragment at the same position as the cowpox-virus Brighton 160 kD gene (1) and the closely related 94 kD LS gene of vaccinia virus strain Western Reserve (2,3). The encoded protein consists of 1049 amino acids with a predicted molecular weight of 122.5 kD, which corresponds well to the apparent molecular weight of 130 kD estimated after polyacrylamide gel electrophoresis and Western blotting. The protein is a characteristic feature of mousepox virus and could be demonstrated for five independently isolated strains. The MP-1 ATI protein displays a similarity of 82.3% to the cowpox virus Brighton 160 kD protein, the first 340 amino acids being almost identical. However, two major deletions of 55 and 92 amino acids were observed from amino acid positions 671 to 732 and 794 to 885, respectively. Furthermore, the C-terminal residues (position 998-1049 of the MP-1 sequence) did not match at satisfactory levels with cowpox nor with vaccinia virus sequences. According to Western blot and protein alignment data as well as hydropathy predictions, the 130 and 160 kD proteins closely resemble each other, indicating similar structure and function.

Amino Acid Sequence↗

PubMed1994

A ligase chain reaction targeting two adjacent nucleotides allows the differentiation of cowpox virus from other Orthopoxvirus species.

A ligase chain reaction (LCR) assay was developed to distinguish cowpox virus from other Orthopoxvirus species. The LCR targets two adjacent adenosine residues which are only present in the A-type inclusion protein gene (ATI-gene) of cowpox virus. Two primer pairs were designed with a one base pair overlap at the junction site and one primer of each pair was labeled radioactively. Detection of the ligation product was achieved after denaturing polyacrylamide gel electrophoresis and autoradiography. Prior to LCR, the corresponding region of the ATI-gene was amplified by a consensus primer-directed polymerase chain reaction. All 18 cowpox virus isolates investigated could be clearly discriminated from 10 vaccinia virus strains, 5 camelpox virus isolates, as well as from mousepox and monkeypox virus reference strains. The LCR method allows a fast identification of cowpox virus isolates and is a feasible tool for the analysis of small mutations within viral genes.

Animals↗

PubMed1994

Sequence alterations within and downstream of the A-type inclusion protein genes allow differentiation of Orthopoxvirus species by polymerase chain reaction.

A PCR protocol was established that not only allows the detection of, but also the differentiation of species of the genus Orthopoxvirus. This assay was accomplished by the selection of oligonucleotides located within the gene that encodes the A-type inclusion protein of cowpox virus. The primer pair flanked a region exhibiting distinct and specific DNA deletions in the corresponding sequences of vaccinia, mousepox, monkeypox and camelpox virus. For this reason, PCR resulted in DNA fragments of different sizes. The presented PCR protocol, combined with BglII restriction digests, allowed the unequivocal assignment of 42 orthopoxvirus (OPV) strains and isolates to the correct OPV species. The resulting classification corresponded exactly with known biological data for the OPV strains investigated. Furthermore, 13 out of 22 cowpox virus isolates could be subtyped by the presence or absence of a small BglII fragment. DNA sequencing showed that the lack of this BglII fragment was caused by a deletion of 72 nucleotides.

Animals↗

PubMed1994

Expression of equine herpesvirus type 1 glycoprotein gp14 in Escherichia coli and in insect cells: a comparative study on protein processing and humoral immune responses.

The extracellular portion (amino acids 1 to 844) of the equine herpesvirus type 1 (EHV-1) glycoprotein gp14, the homologue of gB of herpes simplex virus, was expressed in Escherichia coli and in insect cells using a recombinant baculovirus. Immunoblot analysis revealed that the recombinant E. coli expressed a fusion protein of M(r) 135K which was composed of the truncated gp14 and the maltose-binding protein (MBP) provided by the vector and a 90K protein lacking the MBP moiety. Both proteins were sequestered within the cells in form of inclusion bodies. Infection of insect cells with the recombinant baculovirus resulted in the production of a 115K to 118K glycoprotein which was cleaved intracellularly into two subunits of M(r) 55K and 63K to 65K. The cleaved subunits were secreted into the cell culture supernatant and formed disulphide-linked dimers of M(r) 120K to 122K. The recombinant proteins produced in E. coli and in insect cells elicited EHV-1-specific antibodies in goats as demonstrated by Western blot analysis. The gp14 expressed in insect cells induced antibodies with virus-neutralizing activity. In contrast, the truncated gp14 expressed by E. coli failed to elicit neutralizing antibodies. The results suggest that post-translational modification of the EHV-1 gp14 may be important for the expression of epitopes necessary for the induction of neutralizing antibodies.

Animals↗

PubMed1993

Biopharmaceutical evaluation of transnasal, sublingual, and buccal disk dosage forms of butorphanol.

A series of three-way crossover randomized studies were conducted to evaluate the absolute bioavailability of butorphanol, a potent agonist-antagonist analgesic, from transnasal, sublingual, and buccal disk formulations in order to identify a practical alternative to oral administration. In each study, healthy male volunteers received 2 mg doses of butorphanol tartrate intravenously and either transnasally, sublingually or buccally. Serial blood samples were collected over 12 h and butorphanol plasma concentrations were determined by radioimmunoassay. The plasma concentration data were subjected to non-compartmental pharmacokinetic analysis. The elimination half-life of butorphanol was about 3-5 h and was independent of the route of administration. Absorption of butorphanol following transnasal administration was faster than that observed following sublingual or buccal administration. Mean absolute bioavailabilities of sublingual tablet and buccal disk formulation were only 19 per cent and 29 per cent, respectively, but for transnasal administration the value rose significantly, to 70 per cent. Based on the results of these studies, transnasal dosage form of butorphanol was selected for further clinical trials of treatment of moderate to severe pain.

Administration, Buccal↗

PubMed1993

Localized proton MR spectroscopy of citrate in vitro and of the human prostate in vivo at 1.5 T.

Citrate is a secretory product of the normal prostate, a lack of citrate in prostate tissue is expected to be pathognomonic for adenocarcinoma. In the present study proton AB-signal characteristics of citrate at low field strength of 1.5 T were investigated by volume selective spectroscopic and theoretical methods. The nonappearance of fast phase modulation of the J-coupled system at low field strength in vivo is verified by measurements of sodium citrate solution. In vivo localized spectroscopy of small volume elements of (2 cm)3 with the double spin-echo method within the prostatic gland provides citrate signal reception even using a Helmholtz coil with 170-mm diameter. Volume selective proton spectra with different echo times are presented which are comparable to spectra acquired by former authors with endorectal coils.

Citrates↗

PubMed1993

Differentiation of species of the genus Orthopoxvirus in a dot blot assay using digoxigenin-labeled DNA-probes.

A dot blot assay using five different digoxigenin-labeled probes was established for specific detection and differentiation of four species belonging to the genus Orthopoxvirus. As little as 20 pg orthopoxvirus DNA can be detected, corresponding to approximately 8 x 10(4) DNA molecules. A total of 37 orthopoxvirus strains and isolates of different origin were investigated and could be assigned to the species vaccinia, cowpox, camelpox, and mousepox virus. These findings agree with their identification by biological means. Additionally, a simple procedure to isolate orthopoxvirus DNA directly from scab material was developed. This allows a fast classification without isolating the virus.

Animals↗