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Biomedical subjects

J Pedersen

Publications and source records attributed to J Pedersen.

At least 37 records · Page 2Linked to original sources
PubMed1994

Alterations in intrahepatic expression of duck hepatitis B viral markers with ganciclovir chemotherapy.

Ducks congenitally infected with duck hepatitis B virus (DHBV) were treated with the guanosine analogue, ganciclovir, and the effect on serum and intrahepatic expression of DHBV DNA and viral proteins was examined. After 21 days of ganciclovir treatment, a substantial reduction in viraemia occurred; in contrast, the level of circulating DHBV surface antigen was unchanged. Ganciclovir therapy also substantially reduced the level of DHBV DNA replicative intermediates and the expression of viral core and surface antigen in hepatocytes. However, despite the antiviral treatment some liver cells, including the bile duct epithelial cells and putative oval cells, maintained their intense staining for the viral proteins. Furthermore, DHBV-infected cells in extrahepatic sites such as the pancreas, kidney and spleen were also unaffected by ganciclovir treatment. These results suggest that monotherapy with nucleoside analogues is unlikely to eliminate chronic hepadnaviral infection, and antiviral programs should be designed to target all cell populations infected by the virus.

Animals↗
PubMed1994

Effects of reinforcement history on responding under progressive-ratio schedules of reinforcement.

The effects of experimental history on responding under a progressive-ratio schedule of reinforcement were examined. Sixteen pigeons were divided into four equal groups. Groups 1 to 3 were trained to peck a key for food under a fixed-ratio, variable-ratio, or differential-reinforcement-of-low-rate schedule of reinforcement. After training, these pigeons were shifted to a progressive-ratio schedule, later were shifted back to their original schedule (with decreased rates of reinforcement), and finally were returned to the progressive-ratio schedule. Pigeons in Group 4 (control) were maintained on the progressive-ratio schedule for the entire experiment. To test for potential "latent history" effects, pigeons responding under the progressive-ratio schedule were injected with d-amphetamine and given behavioral-momentum tests of prefeeding and extinction. Experimental histories affected responding in the immediate transition to the progressive-ratio schedule; response rates of pigeons with variable-ratio and fixed-ratio histories were higher than rates of pigeons with differential-reinforcement-of-low-rate and progressive-ratio-only histories. Pigeons with differential-reinforcement-of-low-rate histories, and to a lesser degree pigeons with variable-ratio and fixed-ratio histories, also had shorter postreinforcement pauses than pigeons with only a progressive-ratio history. No consistent long-term effects of prior contingencies on responding under the progressive-ratio schedule were evident. d-Amphetamine and resistance-to-change tests failed to reveal consistent latent history effects. The data suggest that history effects are sometimes transitory and not susceptible to latent influences.

Animals↗
PubMed1994

Comparison of United States and Danish strains of Jerseys for yield traits.

Eleven US and 11 Danish young bulls were AI sampled in the US and Denmark. The milking daughters of these sires provided an opportunity for comparison of the US and Danish Jersey populations. Danish age and month of calving and DIM adjustment factors were developed so that Danish and US records could be compared on a standardized basis (305-d lactation, mature equivalent). Least squares and animal model analyses were used to estimate strain differences and effects of heterosis. Jerseys from the US had superiority over Danish Jerseys of approximately 1000 kg for milk and 17 kg for protein. However, Danish Jersey had an advantage of 20 kg for fat. Estimates of heterosis from crosses of US and Danish Jerseys were 1.5 to 3% of the mean for milk, fat, and protein yields. Correlations of EBV from official genetic evaluations of the US and Denmark were high, > or = .78, for the project bulls, providing little evidence of an interaction of genotype and environment.

Age Factors↗
PubMed1994

Effect of stable xenon inhalation on intracranial pressure during measurement of cerebral blood flow in head injury.

Xenon-enhanced computerized tomography (CT) is well suited for measurements of cerebral blood flow (CBF) in head-injured patients. Previous studies indicated divergent results on whether inhalation of xenon may cause a clinically relevant increase in intracranial pressure (ICP). The authors employed Xe-enhanced CT/CBF measurements to study the effect of 20 minutes of inhalation of 33% xenon in oxygen on ICP, cerebral perfusion pressure (CPP), and arteriovenous oxygen difference (AVDO2) in 13 patients 3 days (mean 1 to 5 days) after severe head injury (Glasgow Coma Scale score < or = 7). The patients were moderately hyperventilated (mean PaCO2 4.3 kPa or 32.3 mm Hg). Six patients were studied before and during additional hyperventilation. All 13 patients reacted with an increase in ICP and 11 with a decrease in CPP. The mean ICP increment was 6.9 +/- 7.7 (range 2 to 17 mm Hg). The mean CPP decrement was -9.7 +/- -14.6 (range 17 to 47 mm Hg). The time course of the ICP changes indicated that ICP increased rapidly during the first 5 to 6 minutes, then declined to a plateau (peak-plateau type in four of 13 patients), remained at a plateau (plateau type in six of 13), or continued to increase in three of 13, indicating individual variance in xenon reactivity. Additional hyperventilation had no effect on the xenon-induced increments in ICP but these occurred at lower ICP and higher CPP baseline levels. The AVDO2 values, an index of flow in relation to metabolism, indicated a complex effect of xenon on CBF as well as on metabolism. This study indicates that xenon inhalation for Xe-CT CBF measurements in head-injured patients according to our protocol causes clinically significant increments in ICP and decrements in CPP. It is suggested that the effect of xenon is analogous to anesthesia induction. Individual variations were observed indicating possible individual tolerance, possible influence of type and extent of the cerebral injury, disturbances in cerebrovascular reactivity, and possible influence of medication. These effects of xenon suggest that hyperventilation should be ensured in patients with evidence of reduced compliance or high ICP. On the other hand, inhalation of stable xenon is not believed to pose a risk because no signs of cerebral oligemia or ischemia were indicated in the AVDO2 values.

Administration, Inhalation↗
PubMed1993

Characterization of Serratia marcescens nuclease isoforms by plasma desorption mass spectrometry.

Isoforms of Serratia marcescens nuclease found in the natural nuclease produced by S. marcescens and in recombinant nuclease produced by Escherichia coli were structurally characterized by peptide mapping using plasma desorption mass spectrometry. The nuclease isoforms produced and secreted from S. marcescens B10M1, which are present in much greater amounts than in S. marcescens W225 nuclease produced by E. coli, were characterized completely and the information used to facilitate characterization of the recombinant nuclease isoforms. After purification of the nuclease the isoforms were separated on a DEAE-cellulose anion-exchange column and then digested with endoproteinase Lys-C. The peptides generated were isolated by reverse-phase HPLC and their molecular masses determined by plasma desorption mass spectrometry. Comparison of the peptides from the native nuclease, Sm2, and the two isoforms, Sm1 and Sm3, revealed that they differed only in the N-terminus, the latter being found to lack three amino acids in Sm1 and one amino acid in Sm3. No interior post-translational changes were found in either of the three isoforms. Using this information we were able to confirm that Sm1, the isoform lacking three amino acids, was also present in very small amounts in recombinant S. marcescens W225 nuclease produced and excreted by E. coli.

Amino Acid Sequence↗
PubMed1993

Separation of isoforms of Serratia marcescens nuclease by capillary electrophoresis.

Three S. marcescens nuclease isoforms differing mainly in charge (native nuclease with pI 6.8 and two minor isoforms with pI 7.3 and 7.4) were separated using several different modes of high-performance capillary electrophoresis. Separation of the isoforms by free solution capillary electrophoresis was unsatisfactory. Separation by micellar electrokinetic capillary chromatography was therefore investigated in detail and the method optimized with respect to pH and sodium dodecyl sulphate concentration; in addition, the effect of adding various substances to control dispersion and avoid analyte adsorption at the capillary wall was examined. Under optimal conditions there was almost complete baseline separation of the two isoforms with basic pI whereas there was only partial separation of the native form and the isoform with pI 7.4. With capillary isoelectric focusing there was complete baseline separation of the native nuclease and the other two isoforms.

Amino Acid Sequence↗
PubMed1993

Interaction of the antiemetic metopimazine and anticancer agents with brain dopamine D2, 5-hydroxytryptamine3, histamine H1, muscarine cholinergic and alpha 1-adrenergic receptors.

The interactions of the antiemetic metopimazine (MPZ) and of the chemotherapeutic agents, cisplatin, carboplatin, doxorubicin, etoposide and vincristine were investigated at five neurotransmitter receptor binding sites. MPZ had nanomolar affinity for alpha 1, dopamine D2 and histamine H1 receptors, weak affinity for muscarinic cholinergic receptors, but no affinity for 5-hydroxytryptamine3 (5-HT3) receptors. Except for vincristine, which showed nanomolar affinity of muscarinic cholinergic receptors, none of the chemotherapeutic agents showed affinity for any of the receptors investigated at concentrations ranging between 10(-5) and 10(-7) M. Accordingly, chemotherapy-induced nausea and vomiting seems to be mediated by mechanisms other than the direct interaction of cytostatics with the neurotransmitter receptors investigated. Our finding that MPZ is without affinity for 5-HT3 receptors and therefore seems to mediate its antiemetic effect predominantly by dopamine D2 receptor blockade makes it an interesting drug for use in combinations with the new class of antiemetics, the 5-HT3 receptor antagonists. Data obtained in a recent clinical trial support this observation.

Animals↗
PubMed1993

Complications and late sequelae following nasotracheal intubation.

A total of 379 patients admitted to the ICU for mechanical ventilation were prospectively investigated for lesions on the nose, nasal cavity, ears and larynx during and after nasotracheal intubation. One to two years later, the surviving patients were questioned to investigate late persisting sequelae. During intubation and up to 5 days following extubation, inflammatory changes and ulceration of the nostrils or nasal septum were found in 76 (20%) and 110 patients (29%), respectively. There were bleedings from the nasal cavity in 67 (19%) and fractures of the conchae in 40 patients (11%). Hoarseness was noted in 135 patients (42%). Inflammatory changes and ulcerations of the nostril and nasal septum were correlated to the duration of intubation. Among the 281 patients included in the follow-up study, 100 (35%) had symptoms from the nose and nasal cavity. Sixty-five (24%) had symptoms related to the ears, 56 (20%) to the maxillary sinus, 81 (29%) to the voice and 90 (32%) to the throat. Increasing duration of intubation was found to be correlated to persisting symptoms from the larynx. Former ulcerations of the nose were associated with a tendency to nasal bleeding. To avoid as many complications as possible from the nose and nasal cavity, we recommend orotracheal intubation. As late sequelae from the larynx increase with the duration of intubation, perhaps tracheostomy should be performed earlier than is general practice today, but that has to be proven in forthcoming studies.

Adolescent↗
PubMed1993

Management of blunt renal trauma.

The management of major renal lacerations after blunt trauma is still a matter of controversy. In this study, conservative treatment of major renal lacerations failed in 7 of 18 patients, leading to delayed surgery. Urography after blunt trauma was abnormal in 97% of patients with severe renal injury but a normal urogram did not exclude severe renal injury. Computed tomography had a greater degree of accuracy than urography and ultrasonography in determining the extent of the injury and was more practical to perform than angiography. The results indicate that patients with significant extrarenal leakage on urography, angiography or CT should receive immediate surgical management.

Adolescent↗
PubMed1993

A new trichrome-blue stain for detection of microsporidial species in urine, stool, and nasopharyngeal specimens.

Detection of microsporidia in clinical specimens has relied on electron microscopy, histology, or staining. This article describes further alterations to the modified trichrome staining method which make it easier to identify microsporidial spores. The changes are a decrease in the phosphotungstic acid level and the substitution of a colorfast counterstain, aniline blue, for the fast green of the original stain. The modified stain provides good contrast between microsporidial spores and background material including human and fungal cells. Stool specimens from 139 human immunodeficiency virus-seropositive patients revealed that 5 patients were infected with Enterocytozoon bieneusi and 6 patients had larger spores. Thin-section electron microscopy of the larger spores showed a structure consistent with that of either Encephalitozoon or Septata species. Three of the patients with Encephalitozoon- or Septata-like species had disseminated infection, with spores detected in nasopharyngeal aspirates and urine samples.

AIDS-Related Opportunistic Infections↗
PubMed1993

Cystectomy and urinary diversion during twenty years--complications and metabolic implications.

A retrospective analysis of 130 cases of cystectomy and urinary diversion for bladder carcinoma was performed. A logistic regression analysis found preoperative irradiation to be associated with early complications (p = 0.014), whereas no such association was observed with late complications. Metabolic evaluation in 51 surviving patients revealed hyperchloremia in 17 patients (33%) and hyperchloremic acidosis in 2 cases (4%). Vitamin B12 deficiency was found in 11 patients (22%), all of whom had preoperative irradiation or reservoir procedures performed. Routine evaluation of vitamin B12 serum levels should be carried out at follow-up in these groups of patients.

Adult↗
PubMed1993

Body satisfaction and self-concept of third- and sixth-grade students.

Pubertal development has been implicated as the point of origin for decreased body satisfaction and self-concept for girls from prepubertal levels and an increase in body satisfaction and self-concept for boys. Two groups of boys and girls in Grades 3 and 6 completed a Body Satisfaction Questionnaire and the Piers-Harris Self-concept Scale to test this assumption. The third graders were considered to be prepubertal and sixth graders as early pubertal. The sixth-grade boys scored lower on body satisfaction than third-grade boys, and their self-concept scores were positively correlated with body satisfaction scores. For girls, body satisfaction scores were correlated with self-concept in both grades, and few significant differences were found between grades. For girls apparently the relationship between body satisfaction and self-concept may be present before the onset of puberty.

Age Factors↗
PubMed1993

Bovine leukocyte adhesion deficiency in Danish Holstein-Friesian cattle. I. PCR screening and allele frequency estimation.

A screening program for bovine leukocyte adhesion deficiency (BLAD) in Danish Holstein-Friesian cattle has been initiated. During the first months 1611 animals were tested by a PCR based assay. Of these animals 1256, 346, and 8 were assigned normal, BLAD carriers, and BLAD affected animals, respectively. One bull, born as a co-twin, showed weak reaction for the BLAD allele on DNA isolated from leukocytes, but a normal genotype on DNA isolated from semen. Chromosome analysis showed that this bull was a blood chimaera. Estimation of the BLAD allele frequency upon the PCR test results showed that around 450 Danish calves born in 1991 might have been affected with the recessive disorder.

Alleles↗
PubMed1993

Characterization of proteinase A glycoforms from recombinant Saccharomyces cerevisiae.

Proteinase A produced by Saccharomyces cerevisiae carrying the gene PEP4 (which encodes the prepro-proteinase A on multicopy plasmids) was isolated and characterized by means of SDS/PAGE, laser desorption m.s. (l.d.m.s.) and high-performance capillary electrophoresis. Although proteinase A is normally located in the yeast vacuole, overexpression resulted in it being secreted. SDS/PAGE revealed that the product isolated from the culture medium comprised an approx, 7:3 mixture of two different forms of proteinase A, the apparent molecular masses of which were 42 and 40 kDa respectively. The exact mass of each form, measured by l.d.m.s., was 40,755 and 38,132 Da respectively. Further analysis employing N-glycosidase F digestion and CNBr cleavage revealed that the larger molecule was native proteinase A bearing carbohydrate moieties at Asn68 and Asn269, whereas the smaller molecule was a proteinase A variant glycoform lacking the carbohydrate moiety at Asn269. Capillary electrophoresis of both the normal and underglycosylated proteinase A glycoforms revealed charge heterogeneities attributable to differences in the phosphorylation level of the carbohydrate moiety at Asn68.

Aspartic Acid Endopeptidases↗
PubMed1993

Characterization of natural and recombinant nuclease isoforms by electrospray mass spectrometry.

Isoforms of natural and recombinant nuclease have been characterized on the basis of their M(r) as determined by electrospray m.s.. The natural nuclease was isolated and purified from Serratia marcescens B10M1 and the recombinant nuclease from Escherichia coli MT102 carrying the plasmid p403-SD2. The primary structure of each of the isoforms isolated from the nuclease preparations was established by comparing their mass with the known amino acid sequence derived from the nucleotide sequence of the nuc gene. All the preparations were found to be contaminated with the same N-terminal split variants of native nuclease, although the natural nuclease contained much larger amounts of these isoforms than did the recombinant nuclease. The structure of some of the isoforms could be verified by N-terminal sequencing, and nearly all of them by isoelectric focusing.

Endodeoxyribonucleases↗
PubMed1992

Correlation of the conformation of a modified ribonuclease octapeptide, homologous to peptide T, with its ability to induce CD4-dependent monocyte chemotaxis.

Peptide T, from the human immunodeficiency virus (HIV), whose sequence is Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr, has been shown to inhibit attachment of this virus to T cells and neural cells bearing the CD4 receptor. This peptide shares extensive homology with the 19-26 segment of ribonuclease A (RNase A), whose sequence is Ala-Ala-Ser-Ser-Ser-Asn-Tyr-Cys. Based on comparison of the structures of peptides occurring in proteins of known structure that are homologous to peptide T, viz, RNase A and endothiapepsin and on conformational energy calculations, we predicted that peptide T adopts a structure much like that for residues 19-26 in RNase A. A critical feature is a bend involving residues Thr 4-Asn 7 in peptide T corresponding to Ser 22-Tyr 25 in the RNase A peptide. Our proposed structure for peptide T has recently been confirmed by Cotelle et al. (Biochem. Biophys. Res. Commun. 171, 596-602). We now show directly that the RNase A peptide, with Met replacing Cys 26 to prevent disulfide exchange reactions, strongly induces monocyte-chemotaxis that is blocked by anti-CD4 monoclonal antibody. Both peptide T and RNase A fail to induce chemotaxis, however, in neutrophils which do not express surface CD4 receptors. These results suggest that both peptides interact with the CD4 receptor in inducing monocyte chemotaxis. We have also prepared cyclo-RNase A peptide with Met 26. Using molecular dynamics and conformational energy calculations, we find that the cyclic peptide cannot form a bend structure involving Ser 22-Tyr 25 that is superimposable on the RNase A bend.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Do burn patients have a silver lining?

Silver-containing pharmacological preparations have been used for many years in the prophylaxis and management of burn wound sepsis and, more recently, 1 per cent silver sulphadiazine cream (SSD) has been the treatment of choice for such problems. A prospective clinical study has been undertaken to determine the absorption and effects of the silver ion from SSD, with particular reference to hepatic and renal function. Twenty-two patients were studied. The silver assay was done by atomic absorption spectrophotometry with an attached graphite furnace. The detection level was 0.5 micrograms/l. The precision at 3.5 micrograms/l was 4.8 per cent and at 8.5 micrograms/l was 2.8 per cent. Silver was rapidly absorbed through the burn wound and serum silver levels were elevated in 20 patients. Silver was found to be deposited biochemically and electronmicrographically in the liver and kidneys of the only patient who died in the study group. Early hepatic dysfunction was present in all burns greater than 10 per cent total body surface area. Liver and renal function tests did not correlate with serum silver levels. A urinary threshold to silver excretion was seen at a serum silver level of 100 micrograms/l. This study demonstrates that silver is rapidly absorbed through burn wounds, is deposited in large amounts throughout the body but appears safe when used in the treatment of moderate burns. Whether the very high levels recorded in the subject who died were inherently detrimental will remain a matter for speculation.

Absorption↗