PubMed Health⌕ Search

Biomedical subjects

G Lindegren

Publications and source records attributed to G Lindegren.

18 recordsLinked to original sources
PubMed2002

Hantavirus infections in Latvia.

In order to investigate the presence of hantavirus infections in Latvia, 333 randomly selected human serum samples were screened using an enzyme-linked immunoassay. Fifteen samples were positive for hantavirus-specific IgG and were subsequently serotyped using a focus reduction neutralization test. Fourteen of these samples neutralized at least one of the hantaviruses included in the test, indicating a 4.2% overall seroprevalence in Latvia. Among 14 focus reduction neutralization test-positive sera, specific reactivity (at least 4-fold higher endpoint titer) of neutralizing antibodies was as follows: six sera were specific for Saaremaa hantavirus, three showed equal titers to Saaremaa and Dobrava hantaviruses, and five showed the highest endpoint titers to Puumala hantavirus. Hantavirus infections were confirmed in individuals residing in 11 of 26 investigated counties. The sex ratio was 1:2.5 (M:F), and the antibody prevalence increased with age. This is the first report on the presence of hantavirus infections in Latvia, and the results indicate that two hantaviruses pathogenic to man, Saaremaa virus and Puumala virus, are widely distributed in this country.

Adult↗
PubMed1989

Diagnosis of influenza A virus infections by detection of specific immunoglobulins M, A, and G in serum.

The value of immunoglobulin M (IgM) detection in the early diagnosis of influenza A was examined in a prospective study during an outbreak of influenza A/Philippines/2/82 (H3N2) virus infection in February and March 1986. The IgM response was investigated in sera from 64 adults with influenzalike symptoms; we found a fourfold rise in titer or high titers (greater than or equal to 80) of influenza A virus antibodies by the complement fixation test. The IgM response, analyzed by the hemadsorption immunosorbent technique, was compared with the IgG and IgA responses analyzed by an indirect enzyme-linked immunosorbent assay and the hemadsorption immunosorbent technique, respectively. Antigen detection in nasopharyngeal secretions by immunofluorescence was performed for all patients on admission to hospital. Specific IgM was detected in 86% (55 of 64) of the patients with influenza A. In sera from 36% (18 of 64) of the patients it was detected already on admission. Influenza A virus antigen was detected in nasopharyngeal cells by immunofluorescence on admission in 53% (34 of 64) of the patients. A combination of immunofluorescence and IgM results gave a significantly higher diagnostic rate, 69% (P less than 0.01), on admission than did each of the two tests separately. An IgA serum antibody response was seen in 76% (48 of 64) of the cases but did not contribute to any increase in the diagnostic rate. IgM detection by the hemadsorption immunosorbent technique was found to be a valuable supplement for the diagnosis of influenza A in an early phase of the disease.

Aged↗
PubMed1968

Biosynthesis of branched-chain amino acids in yeast: correlation of biochemical blocks and genetic lesions in leucine auxotrophs.

The three enzymatic steps in the conversion of alpha-ketoisovalerate to alpha-ketoisocaproate were examined in wild-type and in leucine auxotrophic stocks of yeast. Procedures for the reliable assay of each of the enzymatic steps in crude extracts were devised. Crude extracts of the prototrophic haploid stock catalyzed all three enzymatic steps. Examination of a series of leucine auxotrophs permitted a correlation between the three enzymatic steps and the genetic lesions affecting 10 different loci. This examination revealed that a single locus (le-6) affected primarily alpha-isopropylmalate synthetase, the first step in the pathway. Lesions in six loci (le-1, le-4, le-5, le-7, le-8, and le-10) lead primarily to a deficiency in the activity of the second enzyme in the pathway, alpha-isopropylmalate isomerase. Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. The results with the mutants provide strong evidence that the pathway for leucine biosynthesis proposed by Strassman and his colleagues is the sole significant pathway in yeast.

Genetics, Microbial↗
PubMed1968

Biosynthesis of branched-chain amino acids in yeast: regulation of leucine biosynthesis in prototrophic and leucine auxotrophic strains.

The first enzyme in the biosynthesis of leucine in yeast, alpha-isopropylmalate synthetase, is inhibited by l-leucine. In a mutant resistant to the analogue 5',5',5'-trifluoroleucine, the enzyme is markedly resistant to inhibition by l-leucine. Growth ing the presence of exogenous l-leucine results in repression of the second and third enzymes of the pathway. The first enzyme is not repressed unless both l-leucine and l-threonine are supplied in the medium. Comparison of levels of the remaining two enzymes in leucine auxotrophs grown under conditions of leucine excess and leucine limitation reveals deviations from the wild-type derepression pattern in some mutants. In some, repression of the synthetase by leucine alone was observed. In others, the repressibility of the dehydrogenase was lost. It is unlikely that these deviations were due to the same primary mutational event that caused leucine auxotrophy. No mutants were found in which an altered gene was recognized to be clearly responsible for the level of the leucine-forming enzymes.

Enzyme Repression↗