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L Pettersson

Publications and source records attributed to L Pettersson.

8 recordsLinked to original sources
PubMed1991

Multicomponent polyanions. 45. A multinuclear NMR study of vanadate(V)-oxalate complexes in aqueous solution.

The two complexes formed in the aqueous vanadooxalate system, V(Ox)- and V(Ox)2(3-), have been characterized using 51V, 13C and 17O NMR. For the V(Ox)2(3-) complex, two peaks are observed in 13C NMR and four in 17O NMR. This leads to the conclusion that each oxalate ligand has two different distances to the VO2 group. This fact, together with the peak integrals and the chemical shifts, indicates strongly that the hexacoordinate complex [VO2(C2O4)2]3- found in single-crystal X-ray structure determinations persists in aqueous solution. The dependence of the 13C NMR linewidths upon temperature reveals two types of dynamic processes: (1) a rearrangement in which the two different V-Oox switch places and (2) an exchange of the oxalate ligands in the [VO2(C2O4)2]3- complex with free oxalate, probably through a dissociative process. Rate constants and activation parameters for the two dynamic processes involving [VO2(C2O4)2]3- have been calculated from the shape of the 13C NMR signals. For the V(Ox)- complex, only one relatively narrow peak is obtained in 13C NMR and three peaks in 17O. This fact, as well as the relative positions of these peaks, is in accordance with a pentacoordinate complex [VO2(C2O4)H2O]-, where the two V-O distances to the oxalate ligand are equal. We also show that, in the pH range 0.8-6.6, there is no protonation of the studied complexes, in agreement with previous potentiometric results.

Kinetics↗
PubMed1979

Canine hip dysplasia: study of heritability in 401 litters of German Shepherd dogs.

Heritability of hip dysplasia was estimated to be about 0.4 to 0.5 when based on the radiographic evaluations of the hip joints of 2,404 German Shepherd Dogs born at The Armed Forces Dog Training Center in Sweden. The material included all dogs in 401 litters born at the Center from 1965 through 1973 that reached the age of 15 months. To be expected with such high heritability, frequency of hip dysplasia in the offspring was shown to be affected by the hip joint status of sire and dam as well as by the hip joint status of their parents and littermates. Even matings between sires with normal hip joints and dams with only slight dysplasia resulted in significantly higher frequency of hip dysplasia in the offspring, when compared with the frequency if both sires and dams had normal hip joints. Frequency of hip dysplasia in the progeny of sires with normal hip joints varied greatly. Since 1973, selection of the breeding stock has been based on hip joint status (phenotype) of the breeding animals and of their relatives as well as on what had become known about frequency of hip dysplasia in the litters already born (progeny testing). In this way, frequency of hip dysplasia in 347 dogs born at the Center during 1975 was lowered to 28%. This figure should be compared with the figure of 50%, which represents the frequency of hip dysplasia in the kennel up to 1970, when selection was not as strict as could be expected in a well-controlled kennel.

Animals↗
PubMed1979

Upper respiratory tract spread of group B streptococci type I b in a kindergarten.

In a kindergarten with 42 children and 17 female staff members, an epidemic of group B streptococcal carriage in the upper respiratory tract occurred. In the middle of February 1978, 6 children and 5 adults carried type I b streptococci in the throat while only 2 of these 11 were carriers 2 weeks later. Only one other streptococcus, belonging to type II, was found in the throat specimens. Five strains other than type I b were found in the urogenital tract of the staff. Three type I b throat carriers were also urogenital carriers of this type. The spread of type I b streptococci could have resulted from co-spreading with other upper respiratory tract pathogens found, including group A streptococci of type 12. Haemophilus influenzae, Branhamella catarrhalis and pneumococci. Estimation of antibodies with radiolabelled protein A indicated an immune response to type I b, but not to types I a, II or III group B streptococci in the staff compared with healthy blood donors.

Adolescent↗
PubMed1978

Rectal colonization with group B streptococci: relation to urogenital carriage.

Urethral, cervical and rectal specimens were taken from 92 females and urethral and rectal swabs from 46 males attending a venereological outpatient department. The frequencies of group B streptococci were, in the women: urethra 24%, cervix 14% and rectum 17%; in the males: urethra 22% and rectum 7%. These findings, supported by the results of serotyping, clearly demonstrate that the human urethra is an important site of colonization and do not support the idea that the gastrointestinal canal is the primary site of acquisition.

Adolescent↗
PubMedDate not supplied

[Salmonella bacteria in double cream (author's transl)].

In June 1974 a serious outbreak salmonellosis was reported from the southeast of Sweden. The epidemic was caused by Salmonella typhimurium and spread by infected cream, packed in one-way paper-plastic containers. Ordinary pasteurization of cream purposely infected with the strain in question at 60 degrees for 38 sec or 67 degrees C for 4,5 sec, resulted in a reduction by more than 7 decimal logs (Table I). The decimal reduction time at 60 degrees in cream was estimated to roughly 1.3 sec. The cream, which caused the outbreak, was pasteurized at 90 degrees C for 2-3 sec, which should destroy all salmonella in raw cream. In Sweden pasteurized cream has to be stored at a temperature not higher than 8 degrees C. The isolated salmonella strain was not able to grow at + 8 degrees or at + 10 degrees C during 17 days in pasteurized or UHT-treated cream. During this storage the viable counts were reduced by 79% at 8 degrees and 54% at 10 degrees C. Minimum growth temperature of the strain was 11-12 degrees C. The mean generation time in pasteurized cream at 12 degrees was 9.4 hours and at 15 degrees C 3.4 hours (Fig. 1 and 2). The salmonella strain was able to grow in competition with other bacteria in pasteurized cream even at low levels of infection (Table II). An exposure to a higher temperature, followed by storage at + 8 degrees C did not cause a further growth of salmonella at the low temperature (Fig 3). To avoid a recurrence, the possibility of reinfection of the cream with salmonella has to be further decreased and the cream has to be stored at a low temperature during all the storage period.

Dairy Products↗