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Biomedical subjects

A Carstensen

Publications and source records attributed to A Carstensen.

9 recordsLinked to original sources
PubMed1992

Muscle protein synthesis is impaired in nephrotic rats.

Muscle protein synthesis is impaired in nephrotic rats: muscle and hepatic protein synthesis was measured as the incorporation of [3H]phenylalanine [3H]phe) into muscle and liver in male Sprague-Dawley rats with passive Heymann nephritis (HN) in comparison to both normal male (SDM) and female Sprague-Dawley rats (SDF). Incorporation of [3H]phe was significantly less muscle in HN (1.55 +/- 0.08 x 10(4) cpm/g muscle/h) than in SDM (2.55 +/- 0.14 x 10(4), p < 0.01) and no different than in SDF (1.64 +/- 0.23 x 10(4)). Growth rate was also significantly less in SDF and HN compared to SDM. Total [3H]phe incorporation and the % of [3H]phe incorporated into muscle correlated inversely with urinary albumin excretion in HN (p < 0.01) but not with serum albumin. In contrast, [3H]phe incorporation was increased in livers of HN (13.89 +/- 0.99 x 10(3) cpm/g rat/h) compared to either SDM (5.96 +/- 0.38 x 10(3), p < 0.01) or SDF (4.71 +/- 0.35 x 10(3), p < 0.01). Total liver mass, liver protein content, and the ratio of liver weight/body weight were all increased in HN. There were no differences in liver weight, liver protein content, or the ratio of liver weight/body weight between SDM and SDF. We have previously shown that decreased muscle protein accrual in HN cannot be overcome by increasing dietary protein intake. Hepatic protein synthesis and mass are increased in proteinuric rats while muscle protein synthesis is reduced. As a consequence growth rate and muscle protein accrual are diminished in nephrosis. The mechanism responsible for reduced muscle protein synthesis in the nephrotic syndrome is unknown.

Animals↗
PubMed1991

Multivariable optimization of mechanical ventilation. A linear programming approach.

The proposed method aims at improved ventilatory care with reduced morbidity. It combines two important aspects of mechanical ventilation: gas exchange and lung mechanics. A single criterion was selected as optimization index of lung trauma: peak respiratory power (PRP) defined as the maximum product of pressure times flow during inspiration. Arterial blood gases reflect gas exchange and constitute the constraints of the problem. The constraints as well as the optimization index are expressed as linear functions of the input variables (frequency of breathing, tidal volume, and positive end expiratory pressure). A linear programming approach can therefore be used to determine the values of input variables that minimize PRP and at the same time keep arterial blood gases within the prescribed limits. The coefficients of the constraints and the optimization index equation are found by manipulating input variables in order to obtain four different values of PaO2, PaCO2 and PRP (there are four coefficients in each equation). The coefficients can then be calculated and the optimization procedure run. In a pilot study 5 patients suffering from diseases of varying pulmonary pathology were investigated with this method. In 4 out of 5 the ventilator treatment improved in terms of blood gas values (mean increase in PaO2 was 4.7%) and reduction of mechanical load on the lungs (mean PRP reduction was 20%). Lower PRP is accompanied by lower mean power and pressure values, which results in increased cardiac output. Presently, the main problem is the time it takes to determine the patient coefficients (approx one hour), a procedure that needs to be simplified.

Acute Disease↗
PubMed1989

[Immunomodulation by cryosurgery in malignant melanoma].

Cryosurgery is a well-known, established method for the local destruction of tumor tissue by freezing. The assumption that, in addition to a physical and blood vascular phase, an immunological phase exists, has been discussed by many authors and tested using animal models. These results can only be transferred to humans in a limited sense. During the last year, we initiated a randomized study "Cryosurgery versus Conventional Surgery", whereby the peripheral blood and the normal skin from the areas surrounding the resection were compared. We were able to demonstrate in the peripheral blood of 8 cryosurgery patients a postoperative increase in the total and helper T-cells, HLA-DR-positive cells, and the ratio helper/suppressor T-cells in comparison to preoperative values. In the 8 patients treated with conventional surgery, these parameters decreased slightly or remained the same. The differences were highly significant (p = 0.001) to significant (p = 0.01). The results from the first 16 are patients studied presented and discussed here.

Adult↗
PubMed1986

Fluorescence-activated cell analysis of P-fimbriae receptor accessibility on uroepithelial cells of patients with renal scarring.

Pyelonephritogenic Escherichia coli possess P-fimbriae that bind to uroepithelial cells by recognizing a receptor containing the alpha-D-Galp-(1-4)-beta-D-Galp carbohydrate structure. The accessibility of P-fimbriae receptors was determined using uroepithelial cells from 19 female patients with verified renal scarring and a history of febrile urinary tract infection, and 13 healthy controls. The binding of fluorescein isothiocyanate labeled P-fimbriated Escherichia coli to a large number of uroepithelial cells from each individual was studied using the method of fluorescence-activated cell sorting analysis, which allows examination of a large number of cells and selection of cells of a given size. The uroepithelial cells from the patients exhibited a significantly higher binding capacity to P-fimbriated Escherichia coli than did uroepithelial cells from healthy controls (p less than 0.01). The determination of P-fimbriae receptor accessibility on uroepithelial cells may be useful for detecting risk groups among patients with recurrent urinary tract infections.

Adult↗
PubMed1984

Phorbol esters inhibit the functional activation of cytotoxic precursors in mixed lymphocyte cultures.

We have investigated the effect of phorbol esters on T cell activation and generation of suppressor and cytotoxic activity in mixed lymphocyte cultures (MLC). The presence of 30 nM P(Bu)2 during the sensitization phase inhibited the generation of allospecific cytotoxicity and also decreased the killing potential against NK-sensitive targets. The inhibition was not mediated by direct blocking of the lytic capacity nor by suppression of clonal expansion of cytotoxic cells through modulation of lymphokine production. The presence of P(Bu)2 enhanced cell proliferation, but inhibited the functional activation of lymphocytes and consequent generation of Dr antigen-positive T cells. Because the presence of the compound did not affect the MLC-induced generation of suppressor activity, it is likely that P(Bu)2 selectively blocks the maturation of cytotoxic precursors. Surface-marker analysis with OKT monoclonal antibodies revealed that the effects on lymphocyte activation were associated with a decrease in OKT3 and OKT4 reactivity and an increase in the percentage of OKT8-positive cells. The decrease in OKT4 reactivity was not due to selective loss of this lymphocyte subpopulation, because P(Bu)2 was equally mitogenic for the purified OKT4- and OKT8-positive subsets. The results suggest that the effect of P(Bu)2 on cell differentiation and its ability to modulate the expression of functional markers in lymphocyte subsets may interfere with T-T cell cooperation that controls the functional maturation of cytotoxic precursors.

Antigens, Surface↗
PubMed1984

The B cell mass at the clinical onset of type I diabetes.

In a case of type I diabetes with a duration of 7 days the distribution and volume of the pancreatic endocrine cells were studied using immunocytochemical techniques combined with morphometry. The PP cell rich lobe, making up about 10% of the total pancreatic volume, was not considered in this examination. The volume density and the absolute volume of the B cells was found to be reduced to about one third to one seventh of the values determined in three controls of a similar age and pancreatic volume. The A cell volume was also diminished, whereas the D and PP cell volume remained constant. As B cell necroses could not be detected and insulitis affected only few islets, it was concluded that the destruction of B cells proceeds slowly in type I diabetes and, in the majority of cases, probably starts years before the clinical onset.

Adolescent↗