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Biomedical subjects

J Pedersen

Publications and source records attributed to J Pedersen.

At least 19 recordsLinked to original sources

Experimental vas replacement by either vas or a vascular graft.

An experimental model for vas replacement by transplantation of either vas or a vascular graft in attempt to restore patency in cases of a substance loss of vas that cannot be overcome by vasovasostomy was developed. Three transplant lengths, representing 10, 20 and 30% of the entire vas length, were used. The results showed an overall patency of 43% but for the transplant length representing 10% of the vas patency was achieved in approximately 75% of the cases regardless of the type of transplant used. Unpatency was usually due to occlusion of the proximal anastomosis, which in turn was considered to be due to a combination of unfavourable nutritional, neural and surgical factors. It is concluded that vas replacement by transplantation using either vas or a vascular graft is possible to perform experimentally and gives acceptable patency rates up to a transplant length of 10% of the entire vas length.

Animals

[Serratia marcescens nucleases. I. Comparison of native and recombinant nucleases using electrospray mass spectrometry].

Isoforms of the natural and recombinant nucleases of Serratia marcescens were characterized by their molecular mass, which was determined by electrospray mass spectrometry. The natural nuclease was isolated from the S. marcescens B10M1 culture, whereas the recombinant nuclease was obtained from Escherichia coli MT102 cells carrying plasmid p403-SD2 with the nuclease gene nuc. The primary structure for each of the isoforms isolated from the nuclease preparations was determined by comparing its molecular mass with that of known amino acid sequence, which was determined from the nucleotide sequence of the nuc gene. Both preparations included identical nuclease variants with N-terminal amino acid residues removed. The number of isoforms in the natural nuclease was, however, significantly greater than in the recombinant nuclease. The structures of some of the isoforms were confirmed by N-terminal analysis.

Chromatography, DEAE-Cellulose

[Serratia marcescens nucleases. II. Primary structure analysis by peptide mapping combined with plasma-desorption mass spectrometry].

The primary structures of nucleases Sm1, Sm2, and Sm3 produced by Serratia marcescens were completely characterized using plasma desorption mass spectrometry (PDMS) of proteolytic peptides isolated by reverse-phase HPLC. The isoforms were separated by anion-exchange chromatography on DEAE cellulose and subjected to hydrolysis by the lysine-specific endoproteinase Lys-C. Comparative analysis of the peptides identified by PDMS showed that all three nucleases are N-terminal variants of the same protein: Sm2 represents a "mature" protein form, whereas Sm1 and Sm3 lack three and one N-terminal amino acid residues, respectively.

Amino Acid Sequence

[Nuclease isoforms of natural and recombinant strains of Serratia marcescens. Comparative characteristics of plasma desorption mass spectrometry].

The primary structure of isoforms of natural nuclease secreted by Serratia marcescens as well as of recombinant nuclease produced by Escherichia coli has been characterized by plasma desorption mass spectrometry. The isoforms were isolated from the purified nuclease on a DEAE-cellulose anion-exchange column and digested with endoproteinase Lys-C. The peptides generated were isolated by reversed phase IIPLC and their molecular masses determined by plasma desorption mass spectrometry. Among the nuclease isoforms secreted by parent cells, a new isoform, Sm3, was found. Comparison of the peptides yielded by nuclease Sm2 and two isoenzymes, Sm1 and Sm3, demonstrated their distinction only in the N-termini; three amino acids are lacking in Sm1 and one residue in Sm3. Identity was demonstrated between nucleases Sm1 and Sm2 produced by S. marcescens and the isoforms rSm1 and rSm2 secreted by the recombinant E. coli strain.

Amino Acid Sequence

[Characteristics of isoforms of Serratia marcescens from electrospray mass spectrometry].

Electrospray mass spectrometry was used to determine the molecular masses of nuclease isoforms isolated and purified from the cultural fluid of Serratia marcescens B10M1. The primary structure of each of the isoforms isolated from the nuclease preparations was established by comparing their masses with the known amino acid sequence encoded by the nuc-gene. The structure of some of these isoforms was verified by N-terminal sequencing, that of nearly all isoforms-by isoelectric focusing. All nuclease isoforms were found to be variants of native nuclease split at the molecular N-termini.

Chromatography, DEAE-Cellulose

[Complications and late sequelae after nasotracheal intubation].

A total of 379 patients admitted to the Intensive Care Unit (ICU) for mechanical ventilation were prospectively investigated for lesions of 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 five days following extubation, inflammatory changes and ulceration of the nostrils or nasal septum were found in respectively 76 (20%) and 110 (29%) patients. 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 toward 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

Problems and pitfalls in the use of estimated age in anthropometric measurements of children from 6 to 60 months of age: a case from Mali.

Estimates of the age of children are often used uncritically in anthropometric measures. This study shows that even with construction of calendars for use of determination of age, substantial training, a careful follow-up in the field by research assistants, and control of all questionnaires immediately after the interviews of the caretakers and weighing of the children, errors remain in estimating the age of children. Such errors may affect the results substantially, leading to errors in the estimation of age-based measures of nutritional status. In the case of Northern Mali, the effect was most likely an underestimation of malnutrition by perhaps as much as 10 to 30 percentage points. The biases in age estimation in many cases are not constant across subgroups of a population. Therefore age estimation problems may lead to wrong decisions regarding policy formulation, planning of development programs and activities, identification of target groups, and, in particular, evaluation of programs and activities. In situations where age has to be estimated, anthropometric measurements that are less influenced by errors in age estimation are recommended.

Age Factors

Extent of blood transfusion and cancer-related mortality after cystectomy and urinary diversion for bladder cancer.

OBJECTIVE: To assess the possible adverse effect of peri-operative blood transfusion on cancer-related survival after radical cystectomy for bladder cancer. PATIENTS AND METHODS: The hospital records of 130 patients treated with cystectomy and urinary diversion for bladder cancer between 1967 and 1986 were retrospectively reviewed. RESULTS: Standard proportional hazards estimation revealed tumour stage and radiation response after pre-operative irradiation to be significantly associated with cancer-related mortality, whereas age, tumour grade or the extent of peri-operative blood transfusion were not. In models which allowed time varying effects a significantly changed effect of blood transfusion (> or = 7 versus < or = 6 units) was observed, from an initially insignificantly increased relative hazard (RH) (RH = 1.44 at 6 months) to an insignificantly decreased effect after longer follow-up (RH = 0.53 after 2 years). CONCLUSION: Although no overall association between blood transfusion and cancer-related mortality was found, a tendency towards an increased risk early in the follow-up period was observed if more than 6 units were transfused. However, these results need confirmation in further studies before a restrictive attitude towards peri-operative blood transfusion is recommended.

Adult

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

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

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

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

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

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

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

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

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