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Biomedical subjects

G Jensen

Publications and source records attributed to G Jensen.

At least 109 records · Page 6Linked to original sources
PubMed1994

Renovascular resistance in primary hypertension: experimental variations detected by means of Doppler ultrasound.

OBJECTIVE: To gauge the influence of renovascular resistance changes on blood flow velocity pulsatility in kidneys of hypertensive patients by means of the ultrasonic colour and pulsed-wave Doppler method, since we have previously shown in normotensive subjects that the blood flow velocity pulsatility in renal interlobar arteries varies with changes in renovascular resistance. METHODS: In six male patients with primary hypertension, renal blood flow velocity profiles were investigated by means of duplex ultrasound. Single-kidney renovascular resistance was assessed by measurements of split renal function (gamma-camera renography), renal plasma flow (steady-state para-aminohippurate clearance) and cuff blood pressure. The pulsatility index of the blood flow velocity spectrum in the renal interlobar artery and renovascular resistance were measured either at rest, during infusion of angiotensin II, or after angiotensin converting enzyme inhibition. RESULTS: A significant correlation existed between pulsatility index and renovascular resistance (r = 0.50, P < 0.002), which did not improve after correction for the blood pressure pulsatility. Changes of pulsatility index were more closely related (r = 0.64, P < 0.001) to the corresponding changes in renovascular resistance. CONCLUSIONS: With the two-dimensional image-guided colour and pulsed-wave Doppler method it is possible to assess semiquantitatively small intra-individual changes in renovascular resistance in hypertensive patients by means of pulsatility index measurements. Pharmacologically induced alterations in renovascular haemodynamics may therefore be evaluated with this technique.

Angiotensin II↗
PubMed1993

[Microalbuminuria--a valuable diagnostic parameter].

The concept of microalbuminuria is reviewed. Measuring the urinary albumin excretion rate and testing for microalbuminuria is well established in the control and treatment of patients with insulin-dependent diabetes mellitus. Microalbuminuria predicts nephropathy and early cardiovascular death. In the presence of microalbuminuria, frequent examinations are warranted for early detection of retinopathy, hypertension and for optimizing the glycaemic control. In patients with non-insulin dependent diabetes, the independent value of microalbuminuria as a cardiovascular risk factor is not yet clarified. The urinary albumin excretion rate should be measured at diagnosis, because the indications are that presence of microalbuminuria reinforces the urge to intervene against other well-documented cardiovascular risk-factors (hypertension, dyslipidemia, tobacco and obesity). In the non-diabetic population there is accumulating evidence that an elevated urinary albumin excretion rate is associated with early cardiovascular morbidity and mortality. Large scale cross-sectional and prospective studies are needed in order to further clarify the role of microalbuminuria as an independent risk factor in the background population.

Albuminuria↗
PubMed1993

[Screening of microalbuminuria with the Micral-Test. A semi-quantitative urinary dipstick].

Microalbuminuria, defined as a urinary albumin excretion rate of 20-200 micrograms/min, predicts diabetic nephropathy and cardiovascular disease in diabetic patients. An increased urinary albumin excretion rate is probably also associated with cardiovascular disease in non-diabetic subjects. Thus, screening for microalbuminuria is of major importance. A semi-quantitative urinary dipstick method, Micral-Test, has been developed for this purpose. In a urine sample collected overnight from each of 1359 subjects the Micral-Test was evaluated with a quantitative ELISA-method as the standard. Sensitivity, specificity and diagnostic specificity in detecting microalbuminuria was 92, 58 and 12% respectively. The prevalence of microalbuminuria was 5.6%. In conclusion, the Micral-Test is highly sensitive in detecting microalbuminuria, but at the expense of a relatively high number of false positive tests.

Adult↗
PubMed1993

[No increase in the prevalence of vertebral fractures among postmenopausal women over a 10-year period].

We examined whether the prevalence of vertebral fracture in otherwise healthy, 70-year-old Danish women had increased over a period of ten years. The population-based, epidemiological study included two age-matched, representative samples of postmenopausal women. Group 1 (1979) consisted of 173 healthy women without secondary causes of osteoporosis, Group 2 (1989) of 387 women. X-rays of the thoraco-lumbar spine were assessed for vertebral fracture by five radiological methods. There was no significant difference between the two groups in the prevalence of vertebral fracture and the 95% confidence intervals overlapped completely in all methods. The prevalence rates varied by method from 35% to 80% but the distribution of fracture types was similar in the two groups. We conclude that the prevalence of vertebral fractures due to postmenopausal osteoporosis has not increased since 1979 in suburban Copenhagen, and that comparison of prevalences requires the same method of radiological assessment.

Aged↗
PubMed1993

[Tobacco, lung cancer and chronic obstructive lung disease. Results from the Osterbro study].

Data from The Copenhagen City Heart Study, a prospective population study, were analysed to investigate the influence of the type of tobacco and inhalation on mortality from lung cancer and chronic obstructive pulmonary disease (COPD). The study sample comprised 2986 plain cigarette smokers, 3222 filter cigarette smokers, 1578 smokers of cheroots/cigars, 433 male pipe smokers and 773 smokers smoking more than one type of tobacco. From 1976 to the end of 1989 we observed 268 deaths from lung cancer and 195 deaths, where COPD was considered as either the main or the contributory cause of death. Current smokers of all types of tobacco had a significantly higher risk of mortality from the investigated diseases than never-smokers. In both sexes the risks of death from both lung cancer and COPD were lower in cheroot/cigar smokers and in pipe smokers than in cigarette smokers, but these differences were markedly diminished after an adjustment for the inhalation habit. The present study substantiates that tobacco smoking increases pulmonary mortality. The small differences between the various types of tobacco are probably caused by different inhalation patterns.

Adult↗
PubMed1993

The prevalence of myocardial ischemia six months after thrombolytic treatment of acute coronary episodes. A subset of a placebo controlled, randomised trial, the ASSET Study.

The purpose of this prospectively conducted study was to determine the prevalence of transient myocardial ischemia, evaluated from 24 h continuous ECG monitoring and exercise test, 6 months after inclusion in the Anglo Scandinavian Study of Early Thrombolysis (the ASSET trial, a randomised, placebo controlled study of alteplase for survival in patients with suspected acute myocardial infarction (AMI)), and to relate these findings to development of cardiac events. Of the 58 consecutively studied patients ischemic responses were found in 13 (45%) of 29 patients initially treated with placebo, and in 21 (72%) of 29 alteplase treated patients (P = 0.03). After another 6 months, i.e. 12 months after the acute event, two patients were dead, two had non-fatal reinfarctions and three had coronary artery by-pass surgery in the group with ischemic response; no events were recorded in patients without ischemia (P < 0.05). Alteplase treated patients more often had late myocardial ischemia, and cardiac events were found in patients with ischemia. Since the ASSET trial has demonstrated significantly higher short- and long-term survival rate in the alteplase treated group, it was indicated (1) that alteplase treated patients were better positioned for sustaining subsequent ischemia and thus cardiac events due to preservation of viable myocardial tissue, and (2) that late ischemia in the setting of initial alteplase treatment may convey other information than ischemia occurring in placebo treated patients.

Adrenergic beta-Antagonists↗
PubMed1993

Renal and systemic sympathetic counterregulation in response to vasodilators in renovascular hypertension.

1. Twenty-two patients with renovascular hypertension and significant lateralization of renin secretion were investigated with respect to arterial and renal venous plasma noradrenaline and dopamine concentrations before and 30 min after two different blood pressure-lowering procedures (enalaprilat or dihydralazine intravenously). 2. In one group of patients (n = 10) blood pressure reduction by 7.5 mg of dihydralazine caused stimulation of the renin-angiotensin system and increased heart rate (P < 0.01) as well as arterial and renal venous plasma noradrenaline and dopamine concentrations (P < 0.01 for both). The elevation of the plasma dopamine concentration was more pronounced than that of noradrenaline, yielding increased dopamine/noradrenaline ratios both peripherally (P < 0.05) and in the renal veins (P < 0.05). 3. In the second group of patients (n = 12) a comparable reduction in blood pressure elicited by 1.25 mg of enalaprilat was not accompanied by alterations in heart rate or in noradrenaline or dopamine levels in arterial plasma or renal venous plasma from either kidney. 4. Thus, inhibition of angiotensin-converting enzyme does not elicit the expected sympathetic counter-regulatory response to blood pressure reduction; the mechanism(s) involved remains to be clarified.

Adolescent↗
PubMed1993

Reliability of ACE inhibitor-enhanced 99Tcm-DTPA gamma camera renography in the detection of renovascular hypertension.

Twenty consecutive patients with renovascular hypertension, proven by cure or improvement of hypertension at 1-year follow-up after percutaneous transluminal angioplasty or surgical repair, were studied before intervention by means of gamma camera renography with 99Tcm-diethylenetriaminepentaacetic acid (99Tcm-DTPA) at baseline and after angiotensin-converting enzyme (ACE) inhibition. Sixteen patients underwent bilateral renal vein catheterization for measurement of renal vein renin release and extraction ratios of para-amino-hippurate (PAH) and 51Cr-EDTA before and after acute ACE inhibition. With the limit for a significant change in relative side distribution of 5% or more after ACE inhibition on gamma camera renography 13 patients responded (Group 1), while seven patients (Group 2) had unchanged side distribution. Glomerular filtration rate (GFR), measured with 99Tcm-DTPA, in the affected kidney decreased in Group 1 from 26 +/- 16 ml min-1 to 11 +/- 12 ml min1 (P < 0.0005), while GFR was unchanged in the affected kidney in Group 2, 26 +/- 13 ml min-1 versus 29 +/- 13 ml min-1. Extraction ratios of PAH and 51Cr-EDTA for the affected kidney in Group 1 decreased from 80 +/- 18 to 73 +/- 21% (P < 0.05) and from 16 +/- 5 to 7 +/- 5% (P < 0.005), respectively, while in Group 2 the PAH extraction ratio was not significantly changed, 86 +/- 5 versus 81 +/- 14%, but the 51Cr-EDTA extraction ratio for the affected kidney also decreased from 16 +/- 3 to 8 +/- 4% (P < 0.005). All patients had lateralization of renal vein renin to the affected kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Urinary albumin excretion in a population based sample of 1011 middle aged non-diabetic subjects. The Copenhagen City Heart Study Group.

Increased urinary albumin excretion rate (UAER) especially in the range of 20-200 micrograms min-1, termed microalbuminuria, has been proposed as a risk marker and predictor for cardiovascular disease in non-diabetic subjects. Thus it would be of importance to describe the distribution of UAER in the non-diabetic population. Among 1011 30-70-year-old subjects without diabetes mellitus or urinary tract infection, who were invited to participate in a population based epidemiological study, the albumin concentration was measured in an overnight urine sample. The measurement was performed by an ELISA method. The UAER was calculated in units of micrograms min-1 as urinary albumin concentration x urine volume/urine collection time. The distribution of UAER was positively skewed with a median value of 2.3 micrograms min-1 and a 5-95 interpercentile range of 0-11.0 micrograms min-1. The UAER held constant with age, but males had higher UAER than females, 2.6 (0-13.5) micrograms min-1 vs 2.2 (0-8.3) micrograms min-1; p < 0.005. The prevalence of microalbuminuria, defined as an UAER in the range of 15-150 micrograms min-1 in an overnight urine sample, was 3% (95% C.I. interval: 1.9-4.0). These findings suggest, that the level of UAER which might notify increased cardiovascular risk, is lower than in patients with diabetes mellitus, if it is considered to be of any clinical relevance.

Adult↗
PubMed1992

Acyl-CoA-binding protein/diazepam-binding inhibitor gene and pseudogenes. A typical housekeeping gene family.

Acyl-CoA-binding protein (ACBP) is a 10 kDa protein isolated from bovine liver by virtue of its ability to bind and induce the synthesis of medium-chain acyl-CoA esters. Surprisingly, it turned out to be identical to a protein named diazepam-binding Inhibitor (DBI) claimed to be an endogenous modulator of the GABAA receptor in brain membranes. ACBP/DBI, or proteolytically derived polypeptides of ACBP/DBI, have also been implicated in the control of steroidogenesis in mitochondria and glucose-stimulated insulin secretion. Thus, it appears that ACBP/DBI is a remarkable, versatile protein. Now we have molecularly cloned and characterized the ACBP/DBI gene family in rat. The rat ACBP/DBI gene family comprises one expressed gene and four processed pseudogenes of which one was shown to exist in two allelic forms. The expressed gene is organized into four exons and three introns. There is a remarkable correspondence between the structural modules of ACBP/DBI as determined by 1H nuclear magnetic resonance spectroscopy and the exon-intron architecture of the ACBP/DBI gene. Detailed analyses of transcription of the ACBP/DBI gene in brain and liver were performed to map transcription initiation sites and to examine if transcripts from the ACBP/DBI gene were subject to alternative processing. In both brain and liver, transcription is initiated from two major and multiple minor initiation sites. No evidence for alternative splicing was obtained. The promoter region of the ACBP/DBI gene is located in a CpG island and lacks a canonical TATA box. Thus, the ACDB/DBI gene exhibits all the hallmarks of a typical housekeeping gene.

Animals↗
PubMed1992

Comparative studies between nude and scid mice on the growth and metastatic behavior of xenografted human tumors.

The growth and metastatic behavior of three human tumor cell lines and a human colon carcinoma previously passaged in vivo were compared between nude mice and scid mice after xenotransplantation. The three human tumor lines included a bladder carcinoma (T24B), a melanoma (RPMI 7931) and a lacZ gene-transduced breast cancer (MDA-MB-435 BAG). The lacZ gene codes for beta-galactosidase, which can be stained blue with chromogenic substrate X-gal, thus allowing the highly sensitive detection and quantitative examination of human cancer metastasis in host mice. Adult (7-14 weeks) NMRI nude and C.B-17 SCID mice were inoculated with 0.5-5 x 10(6) tumor cells s.c. Comparable take rate, latent period and growth rate of implanted tumors were observed in nude and scid mice for each of the cell lines tested. At the time of autopsy, which varied from 6 to 11 weeks after inoculation, a significantly higher incidence of spontaneous lung metastasis was discovered in scid mice (96%) than in age-matched nude mice (27%, total P less than 0.001). In vitro assays for NK cell-mediated cytotoxicity revealed no significant differences between the two strains of mice. Our results suggest that nude and scid mice are equally suitable for propagating human tumors. However, the metastatic capacity of human tumor cells appears to be better expressed in scid mice. Scid mice may therefore provide an advantageous model for the study of human tumor metastasis.

Animals↗
PubMed1992

Reduced infarct size in nonreperfused myocardial infarction by combined infusion of isosorbide dinitrate and streptokinase.

The value of thrombolytic therapy in myocardial infarction is well established, while any beneficial effect of adjunct therapy is more uncertain. In a double-blind, randomized, parallel-group study the effect of combined intravenous infusions of streptokinase and isosorbide dinitrate (ISDN) on enzyme-estimated infarct size was investigated. One hundred consecutive patients with strong clinical and electrocardiographic suspicion of myocardial infarction, admitted to the coronary care unit within 8 hours after the onset of symptoms, were given a streptokinase infusion of 1.5 million units for 1 hour and a titrated dose of ISDN or placebo for 48 hours. From isoenzyme B of creatine kinase (CK-B) values measured every 4 hours, the infarct size was calculated and the possible presence of reperfusion was evaluated. The infarct size in patients receiving ISDN infusion was reduced (p = 0.04, one-sided test) compared with placebo. By subdividing the patients according to whether or not reperfusion had occurred, the infarct size appeared to be similar following ISDN and placebo in patients with reperfusion (419 versus 369 U/L), whereas the infarct size in patients not reperfused was markedly reduced after treatment with ISDN (223 versus 1320 U/L, p = 0.003). In conclusion, the present study demonstrates that the infarct size may be reduced by other means than reperfusion and it supports the use of combined infusion of thrombolytic agents and nitrates in patients with suspected myocardial infarction.

Adult↗
PubMed1992

In vitro effects of insulin on aldosterone production in rat zona glomerulosa cells.

Though long standing diabetes mellitus is frequently accompanied by hypoaldosteronism, the role of insulin in this setting has never been clearly established. In the present study we have examined the direct effects of insulin on aldosterone production in rat zona glomerulosa cells in vitro. Insulin is shown to directly stimulate aldosterone production in a dose dependent manner, and to attenuate angiotensin II mediated aldosterone production, without affecting angiotensin II receptor binding kinetics. Insulin had no effect on aldosterone production mediated by the other physiological stimuli (K+ and ACTH). These data suggest a possible interaction between insulin and angiotensin II in the regulation of aldosterone secretion.

Adrenocorticotropic Hormone↗
PubMed1992

Experimental variations in renovascular resistance in normal man as detected by means of ultrasound.

The pulsatility index (PI) of blood flow velocities has been reported to vary with changes in peripheral vascular resistance. Since blood flow velocities can easily be detected with the Echo-Color-Doppler technique in interlobar arteries of normally positioned kidneys, we tried in six healthy volunteers to estimate pharmacological induced variations in renal plasma flow (RPF) and renovascular resistance (RVR) by means of PI measurements. In this study no significant correlation between the absolute values of PI and RVR was found. In order to correct PI for different blood pressure-inputs to the renal artery, PI was divided by the pulsatility of the systemic arterial pressure, i.e. the 'blood pressure index' [BPI = (SAD-DAP)/MAP)], resulting in the 'velocity blood-pressure index' (VBI = PI/BPI), which was significantly correlated with RVR (r = 0.54, P less than 0.01). The pharmacological induced changes of RPF and RVR (delta RPF, delta RVR) were also correlated to the respective changes of PI and VBI (delta PI, delta VBI), with the highest significance when delta VBI was plotted against delta RVR (r = 0.83, P less than 0.0001). VBI, i.e. the pulsatility index of blood flow velocities as corrected for the pulsatility of the driving force, may be a tool for noninvasive assessment of changes in RVR and thereby of importance for the diagnosis and follow-up of renovascular diseases.

Adult↗
PubMed1992

Risk factor analysis for atrophic and exudative age-related macular degeneration. An epidemiological study of 1000 aged individuals.

The relationship between age-related macular degeneration and cardiovascular risk factors and certain life-style factors, collected in the Copenhagen City Heart Study (1981-83), was studied by multiple logistic regression analysis. The ophthalmological study sample comprised 1000 randomly selected persons aged 60 to 80 years. Separate analyses were made for the atrophic and the exudative forms of age-related macular degeneration. Among all the possible risk factors analysed, only three factors were significantly associated with macular degeneration. Age was associated with both atrophic and exudative macular degeneration (P less than 0.01). Among smokers who inhaled, the risk of atrophic maculopathy was 2.5 times higher than among non-smokers (P less than 0.01), whereas the use of hypnotics increased the risk of exudative maculopathy by 3.4 times (P less than 0.01).

Aged↗
PubMed1992

Diagnostic use of renal vein erythropoietin measurements in patients with renal artery stenosis.

The relationship between the renin-angiotensin system and erythropoietin was studied in twenty patients with renal artery stenosis and hypertension. Ten of the patients had a unilaterally activated renin-angiotensin system (group 1), while ten patients had not (group 2). Plasma erythropoietin was simultaneously measured in a brachial artery and both renal veins before and 5 and 30 min after an intravenous injection of 1.25 mg enalaprilat. The mean (+/- SD) arterial erythropoietin concentration was 27.3 +/- 16.8 mU/ml in group 1 and 14.1 +/- 11.3 mU/ml in group 2 patients (P less than 0.05). There was no significant change after enalaprilat i.v. in either group. The venous erythropoietin concentration in plasma from the stenotic kidney did not differ from that of the contralateral kidney. The higher erythropoietin concentration in group 1 patients may be explained by a systemic stimulatory effect of the renin-angiotensin system on erythropoietin production. As no side-differences were found, renal vein as well as peripheral erythropoietin measurements cannot be used as a tool in the diagnosis of the functional significance of a renal artery stenosis.

Adult↗