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Biomedical subjects

T Christensen

Publications and source records attributed to T Christensen.

At least 145 records · Page 8Linked to original sources
PubMed1990

Kidney function and cardiovascular risk factors in non-insulin-dependent diabetics (NIDDM) with microalbuminuria.

Microalbuminuria in non-insulin-dependent diabetes (NIDDM) is a strong predictor of increased mortality. The major causes of death are cardiovascular, whereas end-stage renal failure is of low frequency. To define kidney function and the presence of some assumed cardiovascular risk factors, we compared a group of 19 microalbuminuric NIDDM patients (M), of mean age (+/- SD) 65 +/- 4 years, and known duration of diabetes 8 +/- 7 years, with 19 randomly selected matched normoalbuminuric patients (N). Seven microalbuminuric patients (P) were also studied. Glomerular filtration rate (GFR) did not differ between N and M, whereas kidney volume was increased in M (260.3 +/- 54.1 ml 1.73 m-2) compared to N (220.4 +/- 44.8 ml 1.73 m-2; P = 0.018). The frequency of cardiac disease increased with increasing albuminuria. Glycaemic control did not differ between the groups, but fasting plasma C-peptide levels increased from 2.8 +/- 1.1 micrograms l-1 in N, to 3.7 +/- 1.7 micrograms l-1 in M (P = 0.08), and to 4.2 +/- 1.9 micrograms l-1 (P = 0.03) in P. The lipoprotein profile showed no significant differences, although the LDLcholesterol/HDLcholesterol (LDL-C/HDL-C) ratio tended to rise. A significant correlation was found between C-peptide and LDL-C/HDL-C (r = 0.5; P less than 10(-3]. In conclusion, GFR was not increased, and did not differ between N and M, whereas kidney volume was enhanced in M. Several assumed cardiovascular risk factors showed values of M intermediate between those of N and P.

Aged↗
PubMed1990

Final gastric emptying of solid food in healthy subjects: determined by X-ray examination and radionuclide imaging.

In ten healthy subjects final gastric emptying of solid food was measured by a new scintigraphic method, employing 99mTc labelled pellets, and compared to a radiologic method, employing food with incorporated barium suspension. Final gastric emptying of solid food, measured by the scintigraphic technique, was 5.2 hours and with the radiographic technique 5.5 hours, with no significant difference. It is concluded that significant information concerning gastric emptying of solid food can be obtained by the radiological method.

Adult↗
PubMed1989

Crystallization and X-ray data collection on human growth hormone.

Single crystals of natural sequence human growth hormone have been grown from media containing ethanol, acetone or paraldehyde. Recombinant growth hormone in its native and desamidated form and pituitary hormone have been crystallized. A full native set of diffraction data extending to 3.5 A resolution has been obtained with synchrotron radiation for crystals of recombinant human growth hormone grown from ethanol. The identity of the material in these crystals has been established by anion-exchange chromatography.

Chromatography, Ion Exchange↗
PubMed1989

Cloning and expression of an interleukin-1 beta precursor and its conversion to interleukin-1 beta.

A gene coding for a N-terminal precursor of interleukin-1 beta (IL-1 beta) was cloned and expressed in E. coli. The isolated Met-Glu-Ala-Glu-IL-1 beta precursor was enzymatically converted to IL-1 beta by means of dipeptidylaminopeptidase (DAP I). This method ensured a correct N-terminal residue and the often observed expression of Met-IL-1 beta was thus avoided. The pure and physically homogeneous product exhibited the characteristic properties of natural IL-1 beta. The in vitro biological activity was measured in the lymphocyte-activating factor assay and was compared to that of natural IL-1 beta isolated from stimulated monocyte culture using exactly the same purification procedure. The specific biological activity of both products was 2 x 10(-8) U/mg indicating that the recombinant product exhibits full biological activity.

Amino Acids↗
PubMed1989

Kidney function in newly diagnosed type 2 (non-insulin-dependent) diabetic patients, before and during treatment.

Glomerular filtration rate, kidney volume, and urinary albumin excretion rate were studied in otherwise healthy newly diagnosed Type 2 (non-insulin-dependent) diabetic patients, untreated at diagnosis, after short-term treatment and after 3 months treatment. In 10 patients (Group A) glomerular filtration rate (measured by the plasma clearance of 51-Cr-EDTA) decreased from the time of diagnosis 106.2 +/- 14.6 ml.min-1.1.73 m2(-1) (mean +/- SD) to 95.9 +/- 13.7 ml.min-1.1.73 m2(-1) after 3 months treatment (p = 0.049). At the same time, mean plasma glucose was reduced from 13.3 +/- 3.2 mmol/l to 6.5 +/- 1.1 mmol/l. The fall in mean plasma glucose was correlated to the reduction in glomerular filtration rate, r = 0.76, p = 0.011. Kidney volume as measured by ultrasonic scanning was reduced from 264.0 +/- 33.7 ml/1.73 m2 to 210.8 +/- 23.8 ml/1.73 m2 (p less than 0.005). The relative decline in urinary albumin excretion rate was correlated to the fall in glomerular filtration rate, r = 0.69, p = 0.026. In 15 patients (Group B) 24-h urine collections were made during 9.5 +/- 3.2 days, urinary albumin excretion rate fell from the first to the last day in hospital from 14.0 x/divided by 3.0 micrograms/min (geometric mean x /divided by tolerance factor) to 7.0 x/divided by 2.7 micrograms/min p = 0.015. The relative decline was correlated to the change in mean plasma glucose, r = 0.65, p = 0.032. Thus, kidney function in Type 2 diabetic patients is influenced by metabolic control, although to a lesser extent than is seen in Type 1 (insulin-dependent) diabetic patients with comparable glycaemic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Rhizomucor miehei triglyceride lipase is processed and secreted from transformed Aspergillus oryzae.

The cDNA encoding the precursor of the Rhizomucor miehei triglyceride lipase was inserted in an Aspergillus oryzae expression vector. In this vector the expression of the lipase cDNA is under control of the Aspergillus oryzae alpha-amylase gene promoter and the Aspergillus niger glucoamylase gene terminator. The recombinant plasmid was introduced into Aspergillus oryzae, and transformed colonies were selected and screened for lipase expression. Lipase-positive transformants were grown in a small fermentor, and recombinant triglyceride lipase was purified from the culture broth. The purified enzymatically active recombinant lipase (rRML) secreted from A. oryzae was shown to have the same characteristics with respect to mobility on reducing SDS-gels and amino acid composition as the native enzyme. N-terminal amino acid sequencing indicated that approximately 70% of the secreted rRML had the same N-terminal sequence as the native Rhizomucor miehei enzyme, whereas 30% of the secreted rRML was one amino acid residue shorter in the N-terminal. The recombinant lipase precursor, which has a 70 amino acid propeptide, is thus processed in and secreted from Aspergillus oryzae. We have hereby demonstrated the utility of this organism as a host for the production of recombinant triglyceride lipases.

Amino Acids↗
PubMed1989

Rectal anastomosis with application of luminal fibrin adhesive in the rectum of dogs. An experimental study.

By performing a colorectal anastomosis, the risk of a serious clinical leakage is about 10 percent. On the basis of this, the current study described a combined fibrin adhesive-sutured anastomosis in the rectum performed with interrupted seromuscular sutures externally and fibrin adhesive in the mucosa-mucosa cleft internally. Ten dogs having combined anastomosis were compared with ten dogs having a two-layer sutured anastomosis in the rectum as a control. The median bursting strength in the rectum seven days after the operation was 280 mm Hg (range, 180 to 340 mm Hg) for the combined anastomosis and 260 mm Hg (range, 170 to 405 mm Hg) for the sutured anastomosis in the control group. Two anastomoses with two-layer sutured anastomosis had a leak demonstrated radiographically, while no leakage was demonstrated in the ten dogs with combined anastomosis. In conclusion, intraluminal applied fibrin adhesive may contribute to the security of the sutured rectum-anastomosis.

Anastomosis, Surgical↗
PubMed1989

No microalbuminuria or other adverse effects of long-standing hyperfiltration in humans with one kidney.

Hypertrophy and hyperfiltration are characteristic features of single kidneys and kidneys of patients with insulin-dependent diabetes mellitus (IDDM). In both cases the hyperfiltration has been suggested to be involved in the pathogenesis of renal functional deterioration. We studied the effect of long-standing hyperfiltration on kidney function in 29 subjects with one kidney, three of whom were insulin-dependent diabetics. Four groups were studied: (1) uninephrectomized less than 10 years since uninephrectomy (UN) (n = 7; age, 30 +/- 6 years); (2) uninephrectomized greater than or equal to 10 years since UN (19 +/- 11 years, 10 to 52); n = 14; age, 38 +/- 15 years; (3) congenital unilateral renal agenesis (n = 5, age, 39 +/- 16 years); and (4) IDDM patients with one kidney (n = 3; age, 28 to 52 years; diabetes duration, 8 to 31 years; years with one kidney, 18 to 30). Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by the constant infusion technique, kidney volume (KV) by ultrasonic scanning, and urinary albumin excretion rate (UAE) by radioimmunoassay. In all subjects GFR, RPF, and KV were within the normal range, representing a single kidney hyperfiltration of approximately 70% and hypertrophy of approximately 100%. Only one of the subjects with renal agenesis had an elevated UAE (117 micrograms/min); the remainder had a normal UAE, ie, less than 10 micrograms/min, and the diabetics were below the risk level of 20 micrograms/min. Serum creatinine was normal and BP was slightly elevated in only three subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Ischemic damage in hippocampal CA1 is dependent on glutamate release and intact innervation from CA3.

The removal of glutamatergic afferents to CA1 by destruction of the CA3 region is known to protect CA1 pyramidal cells against 10 min of transient global ischemia. To investigate further the pathogenetic significance of glutamate, we measured the release of glutamate in intact and CA3-lesioned CA1 hippocampal tissue. In intact CA1 hippocampal tissue, glutamate increased sixfold during ischemia; in the CA3-lesioned CA1 region, however, glutamate only increased 1.4-fold during ischemia. To assess the neurotoxic potential of the ischemia-induced release of glutamate, we injected the same concentration of glutamate into the CA1 region as is released during ischemia in normal, CA3-lesioned, and ischemic CA1 tissue. We found that this particular concentration of glutamate was sufficient to destroy CA1 pyramids in the vicinity of the injection site in intact and CA3-lesioned CA1 tissue when administered during control (non-ischemic) conditions. In contrast, the same amount injected during ischemia in the CA3-lesioned CA1 region destroyed pyramidal cells in a widely distributed zone around the injection site in the CA1 region. It is concluded that the ischemia-induced damage of pyramidal cells in CA1 is dependent on glutamate release and intact innervation from CA3.

Amino Acids↗
PubMed1989

Abnormal structure and increased stiffness of the femoral arterial wall in young patients with sustained essential hypertension.

Thickness, elastic modulus, and stiffness of the common femoral arterial wall were estimated in 11 patients with essential hypertension and in 11 age-matched normotensive control subjects by use of an in vivo, non-invasive, ultrasound time-motion display technique (M-mode). Hypertensive patients had significantly higher levels than normotensive subjects with regard to arterial wall thickness (0.23 cm vs. 0.18 cm, medians; P less than 0.01), elastic modulus (10.6 x 10(7) Pa vs. 6.18 x 10(7) Pa, medians; P less than 0.05) and arterial wall stiffness (3.80 x 10(7) Pa vs. 2.07 +/- 10(7) Pa, medians; P less than 0.01). It is concluded that structural changes in the wall of the large arteries contribute to the increase in arterial wall stiffness in young patients with sustained essential hypertension.

Adult↗
PubMed1989

Translation rates of individual codons are not correlated with tRNA abundances or with frequencies of utilization in Escherichia coli.

We analyzed 12 individual codons, which differed widely with respect to the frequency of use in Escherichia coli and the abundance of the corresponding tRNAs, for their influence on the coupling between transcription and translation. This was probed by determining the effects of codon substitutions in the leader peptide gene on transcription past the pyrE attenuator, as described previously by Bonekamp et al. (F. Bonekamp, H. D. Andersen, T. Christensen, and K. F. Jensen, Nucleic Acids Res. 13:4113-4123, 1985). In principle, the results revealed that either RNA polymerase or the (leading) ribosomes pass the different codon strings at different rates. However, under the assumption that the rate of transcription elongation is unaffected by the sequence changes, the results may be interpreted as indicating that different codons are translated at different rates and that these rates do not generally reflect the concentrations of the corresponding tRNAs or the frequencies with which the codons are used in E. coli. Moreover, it seems that codon synonyms that are served by the same isoaccepting tRNA species can deviate as much from each other in translational behavior as synonymous codons that are served by isoacceptors present in the cell in widely different amounts can.

Base Sequence↗
PubMed1989

Glomerular filtration rate and kidney volume in normoalbuminuric non-insulin-dependent diabetics--lack of glomerular hyperfiltration and renal hypertrophy in uncomplicated NIDDM.

UNLABELLED: Glomerular filtration rate (GFR) and kidney volume were evaluated in 18 healthy normoalbuminuric non-insulin-dependent diabetic patients and compared to 12 healthy controls matched for sex, age and body mass index (BMI). The patients (12 males, six females) were 61.6 +/- 3.4 (mean +/- SD) years old, the known diabetes duration was 5 +/- 4.8 years, fasting plasma glucose 8.6 +/- 2.3 mmol/l, urinary albumin excretion rate 7.9 x/divided by 2.0 micrograms/min, BMI 26.8 +/- 2.8 kg/m2 and blood pressure systolic/diastolic 145 +/- 19/82 +/- 7 mmHg. The GFR was measured by the plasma clearance of [51Cr]EDTA, using a single shot procedure. The kidney volume was measured by ultrasonic scanning. The GFR was not increased in diabetics: 100.4 +/- 16.7 ml/min/1.73 m2 as compared to controls: 93.8 +/- 11.4 ml/min/1.73 m2. The kidney volume was similar in the two groups. Diabetics: 231.1 +/- 33.4 ml/1.73 m2. CONTROLS: 236.3 +/- 45.7 ml/1.73 m2. There was a borderline significant correlation between kidney volume and GFR (r = 0.40, p = 0.10) in diabetics. No correlation between glycosylated haemoglobin and GFR was found in diabetics. In contrast to the findings in insulin-dependent diabetes renal hypertrophy and hyperfunction were not characteristic features in this series of non-insulin-dependent diabetics. It is suggested that diabetic glomerulopathy is not always a consequence of long-standing hyperfiltration.

Aged↗
PubMed1989

Suppressed natural killer cell activity in patients with euthyroid Graves' ophthalmopathy.

The purpose of the present study was to determine whether patients with euthyroid Graves' exophthalmopathy have an impaired NK cell function compared to patients with Graves' hyperthyroidism and healthy controls. The NK cell activity measured against K562 target cells was significantly suppressed (p less than 0.01) in patients with euthyroid Graves' ophthalmopathy, whereas the NK cell activity of patients with Graves' hyperthyroidism was not. Although interferon-alpha, interleukin-2 and indomethacin significantly enhanced (p less than 0.01) the NK cell activity in all three groups, none of these agents fully restored the defective NK cell activity in euthyroid Graves' ophthalmopathy. The concentrations in the blood of large granular lymphocytes and CD16 positive cells did not differ between the three groups, furthermore an immunosuppressive serum factor was not detected. The number of effector/target cell conjugates did not differ between patients and controls, whereas the interferon-alpha induced production of a soluble natural killer cytotoxic factor (NKCF) with specificity for NK sensitive target cells was suppressed in patients with Graves' euthyroid ophthalmopathy. We conclude that one of the mechanisms underlying the defective NK cell activity in patients with euthyroid ophthalmopathy may be an impairment of the release of NKCF from the NK cells.

Adolescent↗
PubMed1989

Changes in renal volume during normal pregnancy.

Twenty-four healthy pregnant women with a normal pregnancy demonstrated a significant uniform enlargement of both kidneys. The renal volumes increased by a maximum of 30% during pregnancy. However, this could not be attributed to hydronephrosis, as the patients were selected in such a way that none with pelvectasia participated in the study. All regained normal renal volume within the first week after delivery. It is well known that a glomerular hyperfiltration takes place during normal pregnancy. Possible pathogenetic mechanisms are discussed.

Adult↗
PubMed1989

Fatigue and cardiac and endocrine metabolic response to exercise after abdominal surgery.

Subjective feeling of fatigue was quantified before and 20 days after elective uncomplicated abdominal surgery in 16 otherwise-healthy patients and compared with changes in heart rate and various hormonal and substrate responses to a 10-minute bicycle exercise (65% of preoperative maximal work capacity) preoperatively and postoperatively. Postoperatively, fatigue increased (p less than 0.001) from 3.0 +/- 0.5 to 5.3 +/- 0.5 arbitrary units (mean +/- SEM). Heart rate, plasma catecholamines, and serum growth hormone, lactate, alanine, and glycerol values always increased, whereas serum insulin values decreased in response to exercise (p less than 0.01). During exercise, only heart rate (p less than 0.01) and lactate (p less than 0.05) values were higher postoperatively compared with preoperatively. Increase in fatigue postoperatively correlated significantly to increase in heart rate (p less than 0.01) and correlated positively, but not significantly, to increase in plasma levels of noradrenaline (p = 0.08), growth hormone (p = 0.09), and alanine (p = 0.08) during exercise, but not to increase in serum lactate values (p greater than 0.8). Thus, after uncomplicated surgery, there was increased fatigue and amplified metabolic and cardiovascular response to a given absolute work load. These findings are similar to those observed during detraining and suggest a therapeutic role of exercise in the treatment of postoperative fatigue.

Abdomen↗
PubMed1988

Domain VI of Escherichia coli 23 S ribosomal RNA. Structure, assembly and function.

Domain VI at the 3' end of the 23 S ribosomal RNA from Escherichia coli was prepared using the in vitro T7 RNA polymerase system. Its structure was examined by probing with ribonucleases and chemical reagents, including a psoralen derivative, of various nucleotide specificities, using a reverse transcriptase procedure for analysis. The data provided support for the most recent secondary structure derived from phylogenetic sequence comparisons and for additional structuring that was inferred from earlier experimental data. Moreover, the structure was essentially the same in the free domain, in renatured 23 S RNA and in 50 S subunits. Protein L3 bound to the isolated domain and its binding site was located at a long-range double helix containing a large internal loop. This structure is unusual for a protein-RNA binding site and it may characterize a new (third) class of site. Protein L3 has been implicated, together with L24, in initiating assembly of the 50 S subunit and it shares the exceptional property with L24 that it binds adjacent to the junction of two RNA domains from where it can maximally influence RNA folding. Protein L6 also assembled to domain VI and, in a control experiment, protein L2 bound to isolated domain IV. Domain VI was largely inaccessible in the 50 S subunit and the few accessible RNA sites occurred mainly within conserved sequence regions that constitute potential functional sites. alpha-Sarcin inactivates ribosomes by cutting at one of these sites in 50 S subunits; it also recognized the same site in the free 23 S RNA and in the free domain. Both the EF-Tu ternary complex, and the EF-G ternary complex stabilized by fusidic acid or by a non-hydrolyzable GTP derivative, inhibited alpha-sarcin attack while non-enzymatically bound tRNA did not, thus providing evidence, more direct than before, for the involvement of the RNA region in a common elongation factor binding site.

Autoradiography↗