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Biomedical subjects

L Koskinen

Publications and source records attributed to L Koskinen.

15 recordsLinked to original sources
PubMed1992

Determination of fetal hemoglobin by cation exchange liquid chromatography.

A sensitive liquid chromatographic method for the analysis of the major component of fetal hemoglobin (HbF0) in blood using high-resolution strong cation exchange column is described. The imprecision of the method was assessed in 20 repeated assays of blood samples containing 0.67%, 0.97%, 2.2% and 3.3% of HbF0. Within-assay CVs were 5.0%, 2.8%, 1.8% and 1.5% and between-assay CVs 5.8%, 3.7%, 1.9% and 2.7%, respectively. The HbF0 concentration was stable in EDTA blood for at least 20 days at +8 degrees C and 3 days at +22 degrees C. Blood HbF0 levels (mean +/- S.D.) were 0.41 +/- 0.20% for 21 healthy males, and 0.48 +/- 0.19% for 22 healthy non-pregnant females. The method is simple and reproducible, and allows the sensitive determination of blood HbF0.

Adult↗
PubMed1992

Mumps virus infects beta cells in human fetal islet cell cultures upregulating the expression of HLA class I molecules.

The ability of mumps virus to infect pancreatic Beta cells and cause alterations in their HLA expression was evaluated in cultured human fetal islet cell clusters. Mumps virus could be isolated during the whole culture period (6-8 days) and 60% of cells, including Beta cells, contained viral nucleocapsid protein at the end of the culturing. A minor decrease in insulin secretion was observed in some of the infected cultures. The infection was invariably associated with an increase in the expression of HLA class I molecules. This enhancement was mediated by soluble factors secreted by infected cells. The infection could not induce the expression of HLA-DR molecules. However, external interferon-gamma was able to cause a clear rise in DR-expression which was observed only on non-Beta-cells. Rubella and coxsackie B4 viruses were also able to enhance the expression of class I molecules while herpes simplex virus type 2 was not. The results suggest that certain viruses are able to infect Beta cells and cause alterations in their immunological appearance. Increased HLA class I expression in infected islets may exaggerate the autoimmune process in pre-diabetic individuals by increasing the activity of autoreactive cytotoxic T cells.

Cells, Cultured↗
PubMed1989

Computerized rotometer apparatus for recording circling behavior.

A computerized rotometer for recording rotational behavior in rats is described. The digital pulses derived from the infrared photocell detector induced by animal rotations were input directly to a 20-megabyte microcomputer for on-line recording and were processed further to the Digital Equipment Corporation's VAX computer with the SAS software system for statistical and graphical analysis. The typical results obtained with drugs (apomorphine and amphetamine) eliciting contralateral and ipsilateral rotation in rats with unilateral 6-hydroxydopamine (6-OHDA)-induced lesions of the nigrostriatal dopamine pathway were presented. The effect of catechol-O-methyltransferase (COMT) inhibitor, OR-611, on the potentiation of L-dopa-induced contralateral rotation in 6-OHDA-lesioned rats was also studied. The automation of rotometer apparatus and the speed of data analysis facilitate screening novel antiparkinsonian drugs in rats with unilateral lesions of 6-OHDA.

Animals↗
PubMed1987

Real-time acquisition and analysis of cardiac action potentials and twitches using a programmable digitizer and a microcomputer.

Action potentials and single twitches from papillary muscles were acquired and analyzed in real-time using a programmable digitizer and a microcomputer. This combination provides greater control and flexibility during data acquisition than standard analog-to-digital converters. The present system was designed to facilitate evaluation of experimental drugs. However, the combination of a programmable digitizer and a laboratory microcomputer can be applied to a variety of applications in biomedical research.

Action Potentials↗
PubMed1985

Fluorescein angiography in homozygote and carrier state of progressive retinal atrophy of the poodle; comparative aspects with human retinitis pigmentosa.

Fluorescein angiographic findings in 7 carriers and 7 homozygotes of a recessively inherited disease, generalized progressive retinal atrophy of the poodle, are described in detail and comparisons with 24 healthy control poodles are presented. Two angiographic types of the disease could be distinguished. These are: Type 1, a diffuse, widespread choriocapillaris atrophy associated with retinal vascular and depigmentation changes and Type 2, a predominantly retinal involvement combined with focal choroidal atrophic patches lineating major vessels. These findings share similarities with the observations made of the human disease, retinitis pigmentosa. Unaffected carriers of the disease showed characteristic fundus changes in angiography: patchy, hyperfluorescent depigmentation changes and often minor narrowing and irregularities of the arterioles and poorly visible capillary bed.

Animals↗
PubMed1982

Versatile semiautomated sample processor and gamma counter to increase radioimmunoassay efficiency.

We describe a semiautomated batch-assay system designed to increase the speed and ease of performing radioimmunoassays while maintaining good accuracy and precision. The main components are a programmable pipetting unit (sample processor) and a gamma counter capable of simultaneously counting radioactivity in 12 samples. The processor uses prearranged sets of as many as 24 disposable pipette tips, which eliminates carryover between samples, and features a horizontal shaker and magnetic stirrer; 50 different assay protocols can be selected. Batches of tubes are easily transferred from the sample processor to the incubator and centrifuge. The gamma counter is controlled by a microprocessor, which is also used for data processing. Because the system is based on discrete rather than continuous-flow analysis and because of the ease with which consecutive samples can be processed, more than one operation and several different assays can be accommodated simultaneously, which saves time considerably.

Estriol↗
PubMed1981

Multicomponent radioimmunoassay: simultaneous measurement of choriomammotropin and pregnancy-specific beta1-glycoprotein in pregnancy serum.

We describe a receptacle for use in the simultaneous radioimmunoassay of two serum constituents in a single sample, and the application of this principle for the measurement of human pregnancy serum choriomammotropin and pregnancy-specific beta 1-glycoprotein. The analytical performance of this multicomponent radioimmunoassay approaches that of conventional radioimmunoassays. By following the principle described, it is likely that large numbers of constituents can be efficiently measured in single samples.

Female↗
PubMed1976

A note on craniofacial sutural growth.

The paper presents and discusses some features of sutural structures. Fibre orientation in sutures seems to be quite variable and associated with minute local growth phenomena. Trabecular patterns in bones, reflecting growth, appear to support the idea of the outside determination of growth. The bevelled and interdigitated structures seen in many sutures may be interpreted as an expedient solution to the problem of fast growth.

Animals↗
PubMed1976

Evaluation of radioimmunological methods for assay of plasma and urinary aldosterone.

Two radioimmunological methods for assay of plasma and urinary aldosterone were carefully evaluated. In the plasma method a radioimmunoassay is preceded by chromatography on a Sephadex LH-20 column. The method for urine includes a preextraction, hydrolysis of the acid-labile conjugates of aldosterone, and a radioimmunoassay. Both methods fulfill the criteria of reliability and are suitable for both routine and demanding research assays. The plasma method, using columns of double length, is also applicable to analysis of aldosterone in plasma of newborn children, and pregnant females and in cord plasma. The concentration of plasma aldosterone in healthy subjects on an ad lib salt diet was 162 +/- 93 (S.D.) pmol/1 in the supine position and 312 +/- 217 (S.D.) pmol/1 upright. The urinary excretion of aldosterone in healthy subjects was 28.3 +/- 16.7 (S.D.) nmol/24 h.

Aldosterone↗