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Biomedical subjects

L Janson

Publications and source records attributed to L Janson.

At least 19 recordsLinked to original sources
PubMed1999

Relation of milk production loss to milk somatic cell count.

Milk production loss was studied in relation to increased somatic cell count (SCC). Available data were weekly test-day milk yields and SCC (in 1,000 cells/ml), and mastitis incidences. In total, 18,131 records from 274 cows were used. Production loss was determined for test-day kg milk, kg protein, and kg energy-corrected milk. Least-squares analysis of variance was used to estimate the direct effect of Log10(SCC) on production. The recorded measures of production were first corrected for fixed effects, with adjustment factors estimated from a healthy data-set. The average daily milk yield was 19.7 kg/day in first lactation and 22.0 in later lactations. The geometric mean of SCC was 63.1 in first lactation and 107.2 in later lactations. The incidence of clinical mastitis treated by a veterinarian was 19.8% of the lactations-at-risk. Linear relationships were found between the production parameters and Log10(SCC). Quadratic and cubic effects were evaluated, but were found to contribute little to the overall fit of the models. The individual milk yield loss was 1.29 kg/day for each unit increase in Log10(SCC) for cows in first lactation. Milk yield decreased by 2.04 kg/day per unit Log10(SCC) for older cows. Corresponding values for protein yield were 0.042 and 0.067 kg/day for first and later lactations, respectively.

Animals↗
PubMed1997

Marked effect of beta-lactoglobulin polymorphism on the ratio of casein to total protein in milk.

The relationship between genetic variants for milk protein and the composition of milk was analyzed on 4475 repeated milk samples from individual cows; 371 dairy cows of the Swedish Red and White breed and 204 cows of the Swedish Holstein breed were used. The registrations included percentages of casein, protein, fat, and lactose in combination with milk yield and SCC. The genotype of individual cows for alpha(s1)-CN, beta-CN, kappa-CN, and beta-LG was determined by alkaline and acidic PAGE. A mixed animal model was used for the analysis; beta-LG and aggregate casein genotypes were included simultaneously as separate fixed effects in the statistical model. The results suggest a positive additive effect of the beta-LG B allele on casein content and on the ratio of casein to total protein. For the latter trait, the beta-LG genotype accounted for a relatively large part of the phenotypic variance, corresponding to a reduction in residual variance of 11% when included in the model. The corresponding value for casein content was 0.5%. The lack of unfavorable associations between milk protein variants and the traits included in this study makes the beta-LG gene an obvious candidate when the breeding objective is improved conversion of milk protein into cheese.

Animals↗
PubMed1994

The impact of sperm motility on non-return rate in preselected dairy bulls.

The objective of this study was to investigate whether variation in sperm motility, after preselection of bulls for this trait, has any impact on the non-return rate (NRR). The material consisted of pre- and post-freezing motility records and NRR records from 117 young Al bulls with at least 100 services each. Data representing 2 breeds at 2 different Al studs were analysed within studs. Both quadratic and linear regression analyses were performed to describe the relationship when the fixed effects of herd-year, month and order number of the insemination, parity and breed of the female, and the effects of service bull were considered simultaneously. The overall correlation with NRR was low. Motility before or after freezing never accounted for more than 1% of the variation in any of the adjusted NRR. These results showed that the remaining variation in motility was a poor predictor of NRR, which still showed a substantial variation between bulls. The significant b-values varied between 0.13 and 0.24. A motility threshold level of 50%, which is often stipulated for approval of the semen after freezing, does not seem to be the optimal choice. In order to avoid unnecessary culling, it is therefore advisable to reduce the level below which ejaculates should be rejected. The examination and selection for fertility should be completed by direct recording and evaluation of NRR. How far the motility level should be lowered to allow bulls to be tested for fertility in the field warrants investigation by utilizing semen with different degrees of reduced motility.

Animals↗
PubMed1994

Incidence and causes of adverse outcomes of operation for chronic ischaemia of the leg.

OBJECTIVE: To assess the incidence of adverse outcomes after operation for chronic leg ischemia, to identify risk factors for an adverse outcome at one year, and to evaluate survival after operation. DESIGN: Retrospective study. SETTING: University department. SUBJECTS: 1635 consecutive patients recorded on the Swedvasc registry, 1987-1989. INTERVENTIONS: Data were analysed by logic regression and Cox's proportional hazards model. MAIN OUTCOME MEASURES: Morbidity and mortality at 30 days, one year, and 1000 days. RESULTS: At 30 days 54 of the 609 patients with claudication (8.8%) had either not improved or got worse, and this had increased to 126 (20.7%) at one year. Among the 1026 patients with critical ischaemia 124 had either had their limbs amputated or were dead at 30 days (12.2%), and the corresponding figure for one year was 359 (35.0%). Main factors associated with adverse outcome were age, heart disease, previous vascular surgery, reoperation within 30 days, and the presence of complications. Experience of the surgeon and the type of hospital were less important. At 1000 days 528 of the 609 patients with claudication (86.6%) were alive, compared with 628 of the 1026 with critical ischaemia (61.2%).* CONCLUSIONS: Better selection of patients may improve the survival figures at one year. More aggressive treatment of coexistent diseases may improve the results in the group with claudication.

Adult↗
PubMed1991

Transcription factor requirements for U2 snRNA-encoding gene activation in B lymphoid cells.

Transcription of a human U2 small nuclear RNA(snRNA)-encoding gene in HeLa cells requires a distal enhancer element, which is composed of one octamer motif (Oct) and three Sp 1-binding sites. To study the transcription factor requirement in B-cells, different U2 enhancer constructions were transfected into the lymphoid cell line, BJA-B. The results showed that the activation of U2 snRNA transcription in B-cells also requires an enhancer comprising both the Oct and at least one Sp 1-binding site. Deletion of all the Sp 1-binding sites from the enhancer reduces transcription by 80-90% in HeLa, as well as in BJA-B cells, whereas the removal of the octamer-binding site reduces transcription to levels below detection in both cell types. Enhancers containing a single Oct have, nevertheless, the capacity to partially activate U2 snRNA transcription in both HeLa cells, in which only OTF-1 is expressed, and in BJA-B cells in which OTF-2 is the predominantly expressed octamer-binding factor. The most likely interpretation of our results is that both the ubiquitous transcription factor, OTF-1, and the B-cell-specific transcription factor, OTF-2, can activate U2 snRNA transcription. The results also revealed a similar functional cooperation between the transcription factors which bind to the Oct and the adjacent Sp 1-binding site in BJA-B cells, as has been observed in HeLa cells, since a template which contains a weak binding site for OTFs expresses wild-type levels of U2 snRNA in both cell types when the weak octamer-binding site is combined with a Sp 1-binding site.

B-Lymphocytes↗
PubMed1991

Both Oct-1 and Oct-2A contain domains which can activate the ubiquitously expressed U2 snRNA genes.

The U2 snRNA genes, which are transcribed by RNA polymerase II at high levels in all tissues examined, require both a distal and a proximal sequence element for efficient expression. The distal sequence element which has many properties in common with transcriptional enhancers contains, in addition to Sp1 binding sites, an octamer binding site which mediates activation through interactions with the ubiquitous transcription factor Oct-1. In the present study we have attempted to answer the question whether Oct-1 contains a unique activating domain which is required for activation of snRNA genes or whether ubiquitously expressed and lymphoid specific octamer binding factors both have the capacity to activate snRNA transcription. Our results show that in the presence of Oct-1, overexpression of Oct-2A in HeLa or COS1 cells neither inhibits nor stimulates transcription of U2 constructions which contain octamer binding sites with or without an adjacent Sp1 binding site. Moreover, an Oct-2A--GAL4 fusion protein in which the DNA binding domain of Oct-2A was substituted for by the one of the yeast transcription activator GAL4 activates transcription of a human U2 snRNA gene in which the octamer binding site was replaced by a GAL4 binding site. From the results it is concluded that both Oct-1 and Oct-2A contain domains which can activate the ubiquitously expressed U2 snRNA genes.

Base Sequence↗
PubMed1991

Post-thaw motility, ATP content and cytochrome C oxidase activity of A.I. bull spermatozoa in relation to fertility.

Relationship between post-thaw sperm motility, ATP content, Cytochrome c oxidase (Cco) activity and fertility (56 days non-return) were determined in frozen-thawed semen. Semen was obtained from 47 A.I. bulls, and only ejaculates with a post-thaw sperm motility of greater than or equal to 50% were used. The post-thaw sperm motility was 52.7 +/- 6.9% (means +/- SD) at 30 min. The overall mean concentration of ATP was 18.7 +/- 5.6 nmol/spermatozoa x 10(8). Sperm motility, Cytochrome c oxidase activity and ATP content were found to be related to each other (r = 0.57-0.64; p less than or equal to 0.05-0.001). However, only ATP content showed a statistical significant but negative correlation (r = -0.24) with fertility. No correlation was found between post-thaw motility and fertility (56 days non-return within examined freezings). The results obtained raise doubts about the usefulness of sperm motility as an indicator of the fertilizing ability of frozen-thawed semen with a post-thaw motility of greater than or equal to 50%.

Adenosine Triphosphate↗
PubMed1991

Sperm morphology and fertility in A.I. bulls.

Forty-seven A.I. bulls between 15 and 26 months of age, were used to study the relationship between sperm morphology in fresh semen and fertility (56-day non-return rate) in frozen semen following 11,749 inseminations. The sperm morphology was studied in two freezing operations/bull in a phase-contrast microscope and morphological abnormalities were recorded as a percentage of the total number of counted spermatozoa. Morphological categories used in this study were abnormal heads, detached heads, nuclear pouches, abnormal acrosomes, proximal cytoplasmic droplets, abnormal midpieces and abnormal tails. The greatest mean value recorded for the investigated categories was found for abnormal heads (3.8%) but the majority of morphological abnormalities only occurred in about 1% of all studied spermatozoa. Breed effects were found, with a somewhat higher incidence (p less than or equal to 0.05-0.01) of sperm abnormalities and poorer fertility among SRB than among SLB bulls. Despite the low frequency of sperm abnormalities, statistically significant (p less than or equal to 0.05-0.001) correlations were found between abnormal heads, nuclear pouches and proximal cytoplasmic droplets assessed in fresh semen and fertility (56-day non-return rate) of frozen semen.

Animals↗
PubMed1990

Cooperative interactions between transcription factors Sp1 and OTF-1.

We have examined whether the functional synergism between transcription factors Sp1 and OTF-1 involves cooperativity in binding. To demonstrate cooperativity, synthetic enhancers were constructed in which Sp1-binding sites were combined with various OTF-1-binding sites that differed in their binding affinities. The ability of these constructions to activate transcription from the human U2 small nuclear RNA promoter was measured. The results showed that an Sp1-binding site stimulated transcription 2-fold when combined with a high-affinity binding site for OTF-1. When combined with a low-affinity OTF-1-binding site, in contrast, a 20-fold stimulation of transcription was observed. The stimulatory effect of Sp1 was moreover influenced by the distance between the Sp1- and OTF-1-binding sites and the functional cooperation was mirrored by the cooperative formation of OTF-1- and Sp1-specific protein-DNA complexes in vitro. We conclude from these results that the functional cooperation between OTF-1 and Sp1 involves physical interactions between the two transcription factors resulting in cooperative binding. The results thus reveal a mechanism by which Sp1 can modulate transcription.

Base Sequence↗
PubMed1989

Nuclear factor I can functionally replace transcription factor Sp1 in a U2 small nuclear RNA gene enhancer.

Polymerase II transcription of a human gene for the small nuclear RNA U2 is dependent on two different promoter elements: a TATA-equivalent proximal sequence element and a distal enhancer element, which has been shown to contain Sp1- and octamer-binding sites. We have investigated the functional interplay between these transcription factor-binding sites of the enhancer, following transfection of U2 maxigene constructions into HeLa cells. There is a functional non-additive co-operation between the octamer-binding factor and Sp1, which is not dependent on the evolutionally conserved steric arrangement of these binding sites. We demonstrate that the conserved Sp1-binding site of the U2 enhancer can be fully substituted by a nuclear factor I (NFI) binding site, and that the octamer-binding factor functions in stimulating transcription in conjunction with either Sp1 or NFI. Since the octamer-binding factor is most probably the same protein as nuclear factor III (NFIII), the results imply that the NFI/NFIII complex, involved in adenovirus DNA replication, also can function as an efficient activator of transcription.

Base Sequence↗
PubMed1988

Transcription analysis of a human U4C gene: involvement of transcription factors novel to snRNA gene expression.

We have investigated the promoter requirements for in vivo transcription of a human U4C snRNA gene following transfection into HeLa cells. Two elements required for maximal U4C transcription were identified. The first, located upstream of -50, provides a basal level of transcription 2-3% of the full activity, and probably corresponds to the previously identified snRNA gene proximal element. The distal element, centered around -220, acts as a transcriptional enhancer and contains motifs for three previously recognized transcription factors: the octamer-binding protein, NF-A, which binds to motifs in the distal elements of other snRNA genes, and two factors not previously shown to be involved in snRNA gene transcription, cAMP response element binding protein (CREB) and AP-2. The octamer and putative AP-2 motifs are required for maximal transcription of the U4C gene. Specific binding of NF-A and CREB to the motifs in the distal element has been shown in vitro by DNase I and DMS methylation protection footprint competition analyses using HeLa nuclear extracts. The presence of a binding motif for the inducible factor CREB, together with the transcriptional requirement for the putative AP-2 motif, suggests a means by which expression of snRNA genes might be regulated.

DNA-Binding Proteins↗
PubMed1987

Identification of proteins interacting with the enhancer of human U2 small nuclear RNA genes.

Protein/DNA interactions in the human U2 RNA gene enhancer have been characterized by DNase I footprint and DMS methylation protection analyses. Nuclear factors present in both HeLa and B cell extracts have been shown to protect an approximately 70 bp region from DNase I digestion. DMS and DNase I footprint competition studies demonstrated that the entire footprint can be accounted for by interactions with two previously identified transcription factors. One of these recognizes the so called octanucleotide-motif ATGCAAAT (transcription factor IgNF-A) which has been shown to be essential for transcription. The other is the transcription factor Sp1 which binds to three target sequences located adjacent to the octameric motif. The Sp1 interactions appear to be required for full transcriptional activity. No differences in the DNase I footprint patterns or in the DMS methylation protections were observed when nuclear extracts from HeLa cells, two different B cell lines, or from the adenovirus-transformed 293 cell line were compared.

Base Sequence↗
PubMed1987

Properties of a distal regulatory element controlling transcription of the U2 small nuclear RNA.

The upstream region of human U2 genes contains a distal transcriptional control element, previously mapped between nucleotide (nt) positions -198 and -258 (Westin et al., 1984b). In the present study we show that it resembles transcriptional enhancers in being active even from a distance of 1.4 kb. However, in contrast to most other enhancers it functions unidirectionally in Xenopus laevis oocytes. The distal control element was further mapped by construction of truncated templates for U2 RNA transcription. The results showed that templates, which extended to either of nt positions -214 and -218, were inactive. Templates comprising sequences to nt positions -225 or -226 displayed an intermediate level of activity whereas templates which extend to nt -258 were fully active. It has previously been shown that the human U2 enhancer contains binding sites for the so-called octamer binding protein and for transcription factor Sp1 [Janson et al., Nucl. Acids Res. 15 (1987) 4997-5016]. The partially active templates included one binding site for the octamer binding protein, whereas the fully active template included, in addition, two Sp1 binding sites, thus indicating that these transcription factors are of importance for U2 RNA transcription. The structure of the enhancer was also probed by inserting a pair of complementary synthetic oligodeoxynucleotides which represented the region between nt positions -235 and -215 into a truncated template which lacked the enhancer. The oligodeoxynucleotide enhanced transcription to approximately 50% of the level obtained with templates extending to position -258.

Animals↗