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Biomedical subjects

P Hansen

Publications and source records attributed to P Hansen.

At least 73 records · Page 4Linked to original sources
PubMed1994

Purification of tryptophan containing synthetic peptides by selective binding of the alpha-amino group to immobilised metal ions.

Immobilised metal ion affinity chromatography (IMAC) based on selective binding via the alpha-amino group to Cu2+ and Ni2+ ions has been used to purify tryptophan containing synthetic peptides. A free alpha-amino group, serving as an affinity handle, is present only in the target peptide when the peptides are synthesised by the solid-phase method and remaining amino groups after each coupling step are blocked by acetylation. A free alpha-amino group is necessary to retain the peptide on the column. The tryptophan residue may contribute to the binding only if the peptide is simultaneously anchored via the alpha-amino group.

Acetylation↗
PubMed1993

Synthesis and anti-HIV activity of 5-alkoxymethyl-3'-azido-2',3- dideoxyuridines.

Methyl 3-azido-5-O-tert-butyldiphenylsilyl-2,3-dideoxy-D-erythro-furanosi de (3) was coupled with silylated 5-hydroxymethyluracil (1a) and its C1-C6 alkyl ethers 1b-g to give the corresponding protected nucleosides 4a-g which were deprotected with Bu4NF to afford 3-azido nucleosides 5a-g and 6a-g. The alpha-anomers 6f,g show moderate activity against HIV. No significant activity against HSV-1 was found for the compounds 5 and 6.

Antiviral Agents↗
PubMed1992

Immobilized metal ion affinity chromatography of synthetic peptides. Binding via the alpha-amino group.

Peptides synthesized by the solid-phase method can be efficiently purified in a single immobilized metal affinity chromatography step based on interaction with the alpha-amino group if, after coupling of each amino acid residue, unreacted amino groups are irreversibly blocked by acetylation and if no strongly metal-binding amino acids (His, Trp, Cys) are present in the sequence. A difference in basicity for alpha- and epsilon-amino functions of ca. 2 pH units is sufficiently large to allow selective binding of peptides to immobilized metal ions via the unprotonated alpha-amino group. The binding is pH-dependent: on Cu(2+)- and Ni(2+)-loaded supports most peptides are maximally retarded at pH values around 7.5 and 8.5, respectively. The decreased binding strength at lower pH values is due to protonation of the alpha-amino function, whereas the reduced affinity at higher pH is caused by metal ion transfer from the matrix to the peptide. The metal ion is captured in a multidentate chelate where, in addition to the alpha-amino group, up to three adjacent deprotonated amide nitrogens are coordinated to the metal. If the pH is raised further, additional metal ions may be bound in biuret-like structures. Immobilized Ni2+, owing to its higher selectivity and affinity, is the preferred chromatographic support if slightly basic conditions can be tolerated.

Amino Acid Sequence↗
PubMed1992

The influence of halothane on spermatogenesis in surgical patients.

Seventeen male patients delivered a sperm sample before and 80-90 days after halothane anaesthesia, acting as their own control. The sample was tested according to WHO criteria. There was no difference before and after anaesthesia. We conclude that halothane used in normal anaesthetic concentration in combination with nitrous oxide during arthroscopic knee surgery had no certain effect on the quality of sperm.

Adult↗
PubMed1992

Intranasal administration of insulin with phospholipid as absorption enhancer: pharmacokinetics in normal subjects.

The pharmacokinetics of intranasal insulin containing a medium-chain phospholipid (didecanoyl-L-alpha-phosphatidylcholine) as absorption enhancer, was studied in normal volunteers by measuring plasma glucose, insulin, C-peptide, and glucagon. Eleven fasting subjects received 4 U insulin intravenously, 6 U subcutaneously, or three doses intranasally (approximately 0.3 U kg-1, 0.6 U kg-1, 0.8 U kg-1) in random order on five separate days. Intranasal insulin was absorbed in a dose-dependent manner with a mean plasma insulin peak 23 +/- 7 (+/- SE) min after administration. Mean plasma glucose nadir was seen after 44 +/- 6 min, 20 min later than following intravenous injection. Furthermore, intranasal administration of insulin resulted in a faster time-course of absorption than subcutaneous injection, with significantly reduced intersubject variation (p less than 0.001). Bioavailability for the nasal formulation was 8.3% relative to an intravenous bolus injection when plasma insulin was corrected for endogenous insulin production estimated by C-peptide. A dose-dependent suppression of C-peptide and stimulation of glucagon secretion occurred after intranasal administration of insulin. Nasal irritation from spraying was absent or slight.

Absorption↗
PubMed1992

Costs of asthma.

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Asthma↗
PubMed1991

Cascade-mode multiaffinity chromatography. Fractionation of human serum proteins.

The group-resolving power of cascade-mode multiaffinity column chromatography (CASMAC), was demonstrated with human serum as a model mixture. More than 99% of the serum proteins were adsorbed in the same high salt-containing buffer on a tandem column consisting of (1) immobilized Zn2+ on triscarboxymethyl diamine gel followed by (2) thiophilic (T) gel, (3) Zn2+ bound to the new tridentate chelating adsorbent dipicolylamine (DPA) agarose, (4) hexyl-thioether C6-S agarose and (5) Ni(2+)-DPA agarose. After the adsorption step the immobilized metal ion affinity gels were attached to the top of tandem columns of other adsorbents (T gel, Sephadex G-25 for desalting and Mono-Q) and the elution conditions were selected such that further group separation was achieved. High resolution, high recovery, easy manipulation and high capacity are characteristic features of the cascade process with these adsorbents. The advantage of CASMAC is particularly striking when, with a given number of adsorbents, the overall number of operations involving adsorption, desorption, washing, buffer change and substance concentration can be effectively minimized.

Blood Protein Electrophoresis↗
PubMed1991

New synthesis of 2',3'-didehydro-2',3'-dideoxynucleosides.

The 3'-iodonucleoside 4 and the 3'-O-methylsulfonylthymidine 9 have been synthesized by condensation of silylated uracils 2 with methyl 5-O-tert-butyldiphensilyl-2,3-dideoxy-3-iodo-D-threo-pentofuran oside (3) and methyl 5-O-tert-butyldiphenylsilyl-2-deoxy-3-methylsulfonyl-D-erythro- pentofuranoside (8), respectively. The nucleoside 4 and 9 produced the corresponding 2',3'-didehydro-2',3'-dideoxynucleosides 5 in an elimination reaction on treatment with sodium methoxide. The compounds 5b showed no antiviral activity against HIV-1.

Antiviral Agents↗
PubMed1991

Absorption profiles of rectally administered midazolam estimated by deconvolution.

UNLABELLED: An algebraic deconvolution procedure adopted from the literature has been used to estimate the absorption profiles of rectally administered midazolam (0.3 mg/kg) in 8 healthy subjects. The extent of absorption estimated by the conventional AUC approach has previously been published and was compared to the deconvolution results. In the original study the sampling period was 840 min. When a deconvolution approach is used there may be no need to sample after the absorption is completed. Thus in this communication only samples drawn within the first 120 min and 300 min were used. The bioavailability estimated by the AUC ratio (mean 0.52 +/- SDrel 16%) is compared to the deconvolution results obtained using only data points within 120 (0.46 +/- 22%) (p = 0.02) and 300 min (0.51 +/- 20%) (p = 0.6) after drug administration. The absorption is almost complete after 120 min. Regarding the absorption rates 40% (range 27.55%) of the dose is absorbed after 60 min. The relative (normalised) absorption profiles showed that 79% (range 63-90%) of the maximum absorbed amount is absorbed within 60 min. IN CONCLUSION: Information regarding the rectal absorption of midazolam can be obtained from a sampling period of approximately 5 hours using the deconvolution approach. The algorithm used is relative easy to implement and is very easy to use with polyexponential parameters obtained by curve fitting as input.

Administration, Rectal↗
PubMed1990

[Transfusion reactions after SAG-M blood].

The most common type of transfusion reaction is the febrile reaction, which is often caused by microaggregates in the blood transfused. Reducing the content of microaggregates lowers the rate of transfusion reactions. SAG-M blood is depleted of microaggregates. After changing from whole blood to SAG-M blood, the frequency of transfusion reactions fell from 0,83% to 0,24%.

Blood Group Incompatibility↗
PubMed1990

Iatrogenic aorto-sinus of valsalva fistula: angiographic and cine computerized tomography delineation.

A patient is reported who underwent cardiac catheterization 4 years following coronary artery bypass grafting. Cardiac catheterization revealed the presence of a fistulous tract in the wall of the ascending aorta, originating at the site of aortic anastomosis of a saphenous vein bypass graft and ending in the superior aspect of the right sinus of Valsalva. This complication was felt to have resulted from a inadvertent localized dissection of the aorta during bypass surgery. The fistula was also imaged by ultrafast cine computerized tomography which proved a useful non-invasive method for follow-up examination.

Aortic Diseases↗
PubMed1990

Differential responses to proprioceptive neuromuscular facilitation (PNF) stretch techniques.

The purpose of this study was to investigate the effects of sustained stretch and two common proprioceptive neuromuscular facilitation (PNF) stretch techniques on hamstring muscle activation and knee extension range of motion (ROM) in different athletic populations. Three stretch techniques: stretch-relax (SR), contract-relax (CR), and agonist contract-relax (ACR) were applied to 10 endurance athletes (EN), 10 high intensity athletes (HI), and 10 control subjects (C). The results revealed that ACR produced 89-110% greater hamstring EMG activity (P less than 0.05) and 9-13% more knee joint ROM than CR and SR, respectively. This same pattern was evident for the individual subject groups. Comparisons of mean data among the three subject groups revealed that the EN athletes generated 58-113% more hamstring EMG activity (P less than 0.05) than the HI and C groups, respectively, across all stretch conditions, whereas the EN group attained significantly less ROM than the HI and C groups for CR and ACR conditions. It was postulated that high intensity-short term activity training necessitates less hamstring resistance to knee extension than long term endurance training. The findings suggest that decreases in muscle activity may not be strongly related to increases in joint range of motion and that factors other than muscle relaxation are important in achieving increased ROM. Also, the differential effects of various stretch techniques between dissimilar athletic populations should be considered if stretch-induced injury is to be avoided.

Adult↗
PubMed1989

[Pigmented villonodular synovitis].

Pigmented villonodular synovitis (PVS) is characterized by diffuse or localized proliferation of the synovial membrane in synovial joints, tendon sheaths or bursae. The etiology and pathogenesis are unknown. The condition is most frequently localized to the flexor tendon sheaths. Intraarticular PVS is most frequent in the knee joint. Swelling of the joint and slight pain develop. The localized intraarticular form may result in locking of the joint. The joint fluid is frequently haemorrhagic. The laboratory tests reveal normal findings. X-rays reveal erosion of the bone and cyst formation. Histological examination of the affected tissue is necessary to establish the diagnosis. Treatment consists of surgical excision. In the diffuse intraarticular form, this must take the form of total synovectomy. In cases with recurrence or pronounced destruction of bone, joint replacement may be indicated.

Humans↗
PubMed1989

Postspinal headache in young and elderly patients. Two randomised, double-blind studies that compare 20- and 25-gauge needles.

In two randomised, double-blind studies of elderly patients with a mean age of 68.9 (range 21-88) years and young patients, mean age 29.4 (range 20-40) years, the effect of needle size on the incidence of postspinal headache was compared. The two needle groups, 20- and 25-gauge, were comparable in both studies with regard to number, sex, age and type of surgery. The incidence of postspinal headache in young patients was 27.6% when a 20-gauge needle was used and 12.6% with a 25-gauge needle. There was no significant difference in either the incidence of headache in the elderly patients (10.8% and 7.8%, respectively) or between the sexes. It is concluded that it does not matter if a 20- or a 25-gauge needle is used for spinal analgesia in elderly patients with regard to postspinal headache, but if spinal analgesia is indicated in young patients a fine needle is preferred.

Adult↗