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Biomedical subjects

T Jensen

Publications and source records attributed to T Jensen.

At least 127 records · Page 7Linked to original sources
PubMed1991

Effect of improved metabolic control on loss of kidney function in type 1 (insulin-dependent) diabetic patients: an update of the Steno studies.

We re-examined 69 of the 70 patients entering the two independent Steno Studies of effects of improved metabolic control on progression of late diabetic complications. They were analysed according to an intent to treat after follow-up for 8 years (Steno Study 1) and 5 years (Steno Study 2). The glycaemic control had improved in the insulin infusion group compared with the conventional treatment group (mean HbA1c) by 2.0 +/- 0.6% vs 0.7 +/- 1.2 in Steno Study 1 and by 1.8 +/- 1.2% vs 0.4 +/- 1.3 (p less than 0.01) in Steno Study 2. In the insulin infusion groups three patients had died during episodes of ketoacidosis. These were not caused by malfunction of the insulin infusion pumps. In the conventional treatment groups, three patients suffered five cardiovascular events causing two deaths. From the sixth month of Steno Study 1 the annual change of the glomerular filtration rate was -3.7 (-5.4 to -2.0) ml.min-1.1.73 m-2 vs -1.0 (-2.1 to -0.1) (conventional vs insulin infusion group, mean (95% confidence interval, p less than 0.01]. The change in urinary albumin excretion was associated with the glycaemic control (n = 69, r = 0.49, p less than 0.0002). No progression was observed among 32 patients with low range microalbuminuria (30 to 99 mg/24 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Nonradioactive, sequence-specific detection of RNA in situ by primed in situ labeling (PRINS).

A new method for the detection of RNA in situ is presented. It is based on sequence-dependent annealing of unlabeled specific oligonucleotide primers to intracellular RNA and subsequent chain elongation catalyzed by reverse transcriptase. Under the conditions described, biotin-labeled nucleotides can be incorporated and the cDNA synthesized in situ can thus be detected using fluorescein-conjugated avidin. Compared to traditional in situ hybridization the use of short oligonucleotide primers has the potential advantage of being better to discriminate between closely related RNA transcripts. Compared to in situ transcription with radioactive precursors we find it more attractive to use fluorescein-conjugated avidin as detection system because it allows a more detailed study of cell and signal simultaneously.

Animals↗
PubMed1991

Effects of insulin on renal haemodynamics and sodium handling in normal subjects.

Diabetic patients treated with insulin injected subcutaneously are characterized by peripheral hyperinsulinaemia and an increased mass of total body exchangeable sodium. We hypothesized that this may cause, at least in part, the glomerular hyperfiltration seen in the diabetic state. Six normal subjects were studied on 2 days in random order. Day A: Basal state for 40 min, hyperinsulinaemic euglycaemic clamp for 1 h (insulin infusion rate 2 mU kg-1 min-1 and 50% glucose infusion) and hyperinsulinaemic euglycaemic clamp combined with volume expansion (2 1 isotonic sodium chloride) for 2 h. Day B: as day A, but without insulin and glucose infusion. During combined volume expansion and hyperinsulinaemia an increase in glomerular filtration rate (GFR) (128 +/- 6 vs 117 +/- 8 ml min-1 1.73 m-2, p less than 0.01) and lithium clearance (CLi) (50 +/- 4 vs 33 +/- 5 ml min-1 1.73 m-2, p less than 0.01) was observed compared with basal conditions. GFR and CLi were unchanged during day B. Insulin infusion reduced renal sodium excretion. Absolute proximal tubular reabsorption was unchanged on both days. Insulin infusion without volume expansion caused a decrease of 24% in the fractional distal sodium excretion. Superimposed volume expansion and the concomitant increase in GFR and CLi was accompanied by a subsequent enhanced fractional distal sodium excretion of 27%. The changes in plasma concentrations of aldosterone, renin, angiotensin II, atrial natriuretic peptide and catecholamines did not explain the differences in GFR. An increase in GFR of 10%, comparable with that observed in diabetic patients, was induced by combined hyperinsulinaemia and volume expansion in euglycaemic normal subjects. The enhanced GFR is probably a compensatory response to the sodium retention induced by the action of insulin on the distal tubules.

Adult↗
PubMed1991

Natural history of diabetic complications: early detection and progression.

Until recently Type 1 diabetes has been characterized by a considerable degree of mortality, mainly associated with the development of diabetic nephropathy. Diabetic nephropathy is characterized by persistent proteinuria, decreasing glomerular filtration rate (GFR), increasing blood pressure, and morphological changes. Proteinuria represents a late stage in a prolonged process, which begins at the onset of Type 1 diabetes, when urinary albumin excretion is at the lower end of its normal range (less than 10 mg 24-h-1). However, in those patients who will later develop persistent proteinuria, urinary albumin excretion increases exponentially at about 20% per year. These patients also tend to have rising blood pressure and falling GFR, higher rates of proliferative retinopathy and coronary heart disease, and elevated levels of cardiovascular risk factors. As intervention is possible in all these areas, identification of such patients is required and especially as the imposition of strict metabolic control may postpone or arrest progression to overt nephropathy. Where patients deteriorate despite such control the institution of early antihypertensive therapy and the effective management of end stage renal disease will bring further improvements in the prognosis of diabetic nephropathy.

Adult↗
PubMed1991

Impaired left-ventricular function in insulin-dependent diabetic patients with increased urinary albumin excretion.

Cardiac function was studied in 30 patients with insulin-dependent diabetes mellitus. Three groups, matched for age and diabetes duration, were defined as: group I (n = 10), normal urinary albumin excretion less than 30 mg 24 h-1; group II (n = 10), incipient diabetic nephropathy (urinary albumin excretion in the range of 30-300 mg 24 h-1); and group III (n = 10), clinical diabetic nephropathy (urinary albumin excretion greater than 300 mg 24 h-1). Ten non-diabetic subjects matched for sex and age served as controls. The left-ventricular end-diastolic volume measured by radionuclide cardiography was, at rest and during exercise, lower in group II and III compared with controls (p less than 0.05), while intermediate values were found in group I. The cardiac output was similar in the control group and group I; it was reduced, but not significantly so (p = 0.10), in group III and was significantly lower in group II (p less than 0.05). Stroke volume was also lower in group II and III than in controls (p less than 0.05), but not so in group I. These differences could not be explained by differences in metabolic control, blood pressure, blood volume status, degree of autonomic neuropathy or frequency of coronary heart disease. Our results might suggest that insulin-dependent diabetic patients with slightly but persistently elevated urinary albumin excretion have reduced diastolic compliance of the left-ventricle leading to impaired cardiac performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

An assessment of the biological capacity of a Sacramento Valley population of Aedes melanimon to vector arboviruses.

Daily survivorship, duration of the gonotrophic cycle, absolute abundance and season-long relative abundance were estimated for Aedes melanimon in the Sacramento Valley of California in 1987 and 1988 using mark-release-recapture (MRR) techniques and by monitoring changes in the abundance and parity rate of the native population. One objective of these studies was to determine the extent to which A. melanimon was biologically capable of serving as a horizontal arbovirus vector. Daily survivorship was estimated to be 0.90 and 0.84 in MRR studies conducted in September 1987 and August 1988, 0.89 based on changes in the parity state and abundance of the native population in August 1988 and 0.82 using summer-long parity data in 1988. Gonotrophic cycle length (GCL) was estimated to be five days in three studies. Aedes melanimon densities were estimated to be approximately 1,000,000 and 15,000 females per hectare in September 1987 and August 1988 respectively. Parous A. melanimon females were collected on each sampling occasion from April to November 1988, suggesting that A. melanimon maintained a continuous presence in the study area throughout the summer. The results of these studies suggest that A. melanimon has the potential to be an efficient horizontal vector of western equine encephalomyelitis (WEE), based on high adult survivorship, short GCL, high abundance and a continuous presence across the summer. This supports the concept of a WEE transmission cycle in the Sacramento Valley involving Ae. melanimon as an important vector. Aedes melanimon also can be an efficient horizontal vector of California encephalitis virus (CE), though the importance of horizontal transmission to the maintenance of CE virus is unclear.

Aedes↗
PubMed1991

Albuminuria--a marker of renal and generalized vascular disease in insulin-dependent diabetes mellitus.

Atherosclerotic vascular disease is a major cause of morbidity and mortality in insulin-dependent diabetes mellitus. The frequent coexistence in these patients of microangiopathy and coronary artery disease was observed more than 30 years ago and later verified in large epidemiological studies. Thus, the subgroup (30-40%) of patients who develop clinical nephropathy, also are at extremely high risk of early cardiovascular death. A number of established cardiovascular risk factors are present not only in advanced clinical nephropathy but also in its earliest stages. These include elevated blood pressure, atherogenic changes in the plasma concentrations of lipids and lipoproteins, elevated plasma levels of fibrinogen and probably hyperreactivity of platelets. However, it seems unlikely that these risk factors fully explain the excess cardiovascular morbidity and mortality in insulin-dependent diabetic patients with clinical nephropathy. Patients with slightly elevated urinary albumin excretion are at increased risk of developing not only clinical nephropathy and coronary heart disease but also proliferative retinopathy and cardiomyopathy. We have, therefore, hypothesised that elevated urinary albumin excretion is a marker of generalized disease in the vascular wall of small and large blood vessels. Findings of elevated transcapillary escape rate of albumin, elevated plasma concentration of von Willebrand factor and impaired fibrinolytic capacity in early diabetic nephropathy have supported this hypothesis. However, the initial pathophysiological mechanisms involved are still hypothetical and largely unknown. During recent years the incidence of clinical nephropathy has declined and the prognosis of insulin-dependent diabetic patients has improved. Whether intervention directed against the often clustered cardiovascular risk factors will further improve the prognosis in proteinuric patients is suggested but still unknown. However, the key question is still, why is the vascular wall, in small and large blood vessels, vulnerable in some but not all diabetic patients? In the future more studies of the initial pathophysiological mechanisms involved in this vulnerability are needed.

Albuminuria↗