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Biomedical subjects

G Samuelsson

Publications and source records attributed to G Samuelsson.

At least 19 recordsLinked to original sources
PubMed2000

Client expectations and satisfaction of quality in home care services. A consumer perspective.

This study examines clients' expectations of quality in home care services and their perceived satisfaction with services among a random sample of 76 home care recipients in Vancouver, Canada. The researchers conducted face-to-face interviews that applied Multiattribute Utility Technology, a procedure that organizes several quality attributes of "ideal" home care into a tree structure to compare their relative importance and ranking from the clients' perspective. Participants also were asked to state their satisfaction or dissatisfaction with the services received in these domains. Among the five main quality attributes identified, the subjects ranked suitability of the home helper and its subset, personal competence, as the most important indicators of quality, followed by continuity in service. In addition, clients tended to have a high level of satisfaction with regard to the attributes of overall home care services. The highest level of satisfaction was reported for elements of personal dispositions of home care staff. The lowest level of satisfaction involved the time/availability components of the service. Finally, comparisons between client expectations and satisfaction of received home care services showed the highest discrepancy for the attributes of influence and time/availability and the greatest congruence for personal attributes of the staff. The results are discussed in terms of their implications for the delivery of home care services.

Aged↗
PubMed1999

Role of a novel photosystem II-associated carbonic anhydrase in photosynthetic carbon assimilation in Chlamydomonas reinhardtii.

Intracellular carbonic anhydrases (CA) in aquatic photosynthetic organisms are involved in the CO2-concentrating mechanism (CCM), which helps to overcome CO2 limitation in the environment. In the green alga Chlamydomonas reinhardtii, this CCM is initiated and maintained by the pH gradient created across the chloroplast thylakoid membranes by photosystem (PS) II-mediated electron transport. We show here that photosynthesis is stimulated by a novel, intracellular alpha-CA bound to the chloroplast thylakoids. It is associated with PSII on the lumenal side of the thylakoid membranes. We demonstrate that PSII in association with this lumenal CA operates to provide an ample flux of CO2 for carboxylation.

Algal Proteins↗
PubMed1999

Concentrations of plasma methylmalonic acid in 80-year-olds show only weak relation to psychological performance.

Most studies of the relation between psychological performance in the elderly and deficiencies of cobalamin and folate have used methods that determine the blood concentrations of these vitamins, which might not reflect the vitamin status in the tissues. Recently, two new markers, plasma homocysteine and methylmalonic acid, have attracted growing interest since they are considered to reflect the status of cobalamins and folates in the tissues. In a previous study, we noted a strong association between five parameters of well-being and lower concentrations of plasma homocysteine. In the present study, we have extended these observations by determination of plasma methylmalonic acid in the same healthy elderly population. In the present study, 18 out of 100 subjects had increased plasma methylmalonic acid and in 7 of these subjects, the concentrations of serum cobalamin, blood folate, plasma homocysteine and serum creatinine were within normal limits. The relation between plasma methylmalonic acid concentrations and concentrations of serum cobalamin and blood folates and five parameters of well-being were investigated. Concentrations of plasma methylmalonic acid were only weakly associated with the concentrations of serum cobalamin and lower scores on the logical reasoning test. The present study clearly shows that the levels of plasma methylmalonic acid show a much lesser association with the parameters of well-being than did plasma homocysteine.

Aged↗
PubMed1999

Social relationships and health as predictors of life satisfaction in advanced old age: results from a Swedish longitudinal study.

This longitudinal study examines the relationship between family and friend social support, health, and life satisfaction for a single cohort of eighty-year-old persons living in Lund, Sweden. Results indicate that participants who remained in the study are healthier and score higher on life satisfaction when compared with those who either drop-out or die prior to age eighty-three. Even though well-integrated with family and friends, the number of friends decreases significantly from eighty to eighty-three years; those who reported no close friends nearly doubled from eighty to eighty-three years. However, for those with close friends, contact with friends increases with age. In contrast to previous research, a correlational analysis indicates that neither child nor friend support is related to life satisfaction at either eighty or eighty-three years. However, health measures and satisfaction with sibling contact are related to total life satisfaction at age eighty-three only. These findings indicate the multidimensionality of both social support and life satisfaction for the old-old.

Adult↗
PubMed1998

A novel alpha-type carbonic anhydrase associated with the thylakoid membrane in Chlamydomonas reinhardtii is required for growth at ambient CO2.

A 29.5 kDa intracellular alpha-type carbonic anhydrase, designated Cah3, from the unicellular green alga Chlamydomonas reinhardtii is the first of this type discovered inside a photosynthetic eukaryote cell. We describe the cloning of a cDNA which encodes the protein. Immunoblot studies with specific antibodies raised against Cah3 demonstrate that the polypeptide is associated exclusively with the thylakoid membrane. The putative transit peptide suggests that Cah3 is directed to the thylakoid lumen, which is confirmed further by the presence of mature sized Cah3 after thermolysin treatment of intact thylakoids. Complementation of the high inorganic carbon concentration-requiring mutant, cia-3, with a subcloned cosmid containing the cah3 gene yielded transformants that grew on atmospheric levels of CO2 (0.035%) and contained an active 29.5 kDa alpha-type carbonic anhydrase. Although, cia-3 has reduced internal carbonic anhydrase activity, unexpectedly the level of Cah3 was similar to that of the wild-type, suggesting that the mutant accumulates an inactive Cah3 polypeptide. Genomic sequence analysis of the mutant revealed two amino acid changes in the transit peptide. Results from photosynthesis and chlorophyll a fluorescence parameter measurements show that the cia-3 mutant is photosynthetically impaired. Our results indicate that the carbonic anhydrase, extrinsically located within the chloroplast thylakoid lumen, is essential for growth of C.reinhardtii at ambient levels of CO2, and that at these CO2 concentrations the enzyme is required for optimal photosystem II photochemistry.

Amino Acid Sequence↗
PubMed1998

Induction and Regulation of Expression of a Low-CO2-Induced Mitochondrial Carbonic Anhydrase in Chlamydomonas reinhardtii

The time course of and the influence of light intensity and light quality on the induction of a mitochondrial carbonic anhydrase (CA) in the unicellular green alga Chlamydomonas reinhardtii was characterized using western and northern blots. This CA was expressed only under low-CO2 conditions (ambient air). In asynchronously grown cells, the mRNA was detected 15 min after transfer from air containing 5% CO2 to ambient air, and the 21-kD polypeptide was detected on western blots after 1 h. When transferred back to air containing 5% CO2, the mRNA disappeared within 1 h and the polypeptide was degraded within 3 d. Photosynthesis was required for the induction in asynchronous cultures. The induction increased with light up to 500 mumol m-2 s-1, where saturation occurred. In cells grown synchronously, however, expression of the mitochondrial CA was also detected in darkness. Under such conditions the expression followed a circadian rhythm, with mRNA appearing in the dark 30 min before the light was turned on. Algae left in darkness continued this rhythm for several days.

Journal Article↗
PubMed1998

Insomnia in an 80-year-old population: relationship to medical, psychological and social factors.

In this study, insomnia in 80-year-olds was related to medical, psychological and social factors. The data were based on examinations every year in people aged between 80 and 89 years. Of 333 people living in the city of Lund and born in 1908, 67% participated. Increased severity of insomnia was significantly associated with use of diuretics, other cardiovascular drugs, hypnotics and laxatives, and with nervousness, difficulty relaxing, anorexia, nausea, constipation, backache, feeling cold, sweating, loss of weight, dizziness, depression, general fatigue, exhaustion, angina pectoris, cardiac insufficiency, worsened objective and subjective health, presence of negative T-waves on ECG, anxiety, total life satisfaction, neuroticism, disbelief in a just world, feeling lonely and lower survival rates. Thus insomnia has widespread associations with different aspects of life in 80-year-olds.

Aged↗
PubMed1998

Intracellular beta-carbonic anhydrase of the unicellular green alga Coccomyxa. Cloning of the cdna and characterization of the functional enzyme overexpressed in Escherichia coli.

Carbonic anhydrase (CA) (EC 4.2.1.1) enzymes catalyze the reversible hydration of CO2, a reaction that is important in many physiological processes. We have cloned and sequenced a full-length cDNA encoding an intracellular beta-CA from the unicellular green alga Coccomyxa. Nucleotide sequence data show that the isolated cDNA contains an open reading frame encoding a polypeptide of 227 amino acids. The predicted polypeptide is similar to beta-type CAs from Escherichia coli and higher plants, with an identity of 26% to 30%. The Coccomyxa cDNA was overexpressed in E. coli, and the enzyme was purified and biochemically characterized. The mature protein is a homotetramer with an estimated molecular mass of 100 kD. The CO2-hydration activity of the Coccomyxa enzyme is comparable with that of the pea homolog. However, the activity of Coccomyxa CA is largely insensitive to oxidative conditions, in contrast to similar enzymes from most higher plants. Fractionation studies further showed that Coccomyxa CA is extrachloroplastic.

Amino Acid Sequence↗
PubMed1997

Carbon dioxide and light regulation of promoters controlling the expression of mitochondrial carbonic anhydrase in Chlamydomonas reinhardtii.

Nuclear genes coding for carbonic anhydrase, a major mitochondrial constituent in Chlamydomonas reinhardtii grown under limited CO2, were characterized. Two genes, ca1 and ca2, were found within 7 kb of genomic DNA, organized 'head to head' in a large inverted repeat. The DNA sequences for the two genes were very similar, even in the promoter regions and in introns, indicating that the repeat is a result of a recent duplication. To study gene regulation, elements from the upstream region of ca1 were fused to the arylsulphatase reporter gene. After transformation, the expression of arylsulphatase was regulated similarly to the endogenous ca1/ca2 genes, even when the promoter was trimmed down to 194 nt. Expression could not be detected when 5% CO2 was bubbled into the growth medium, but was induced within hours after transfer to air. The ca1 promoter was not induced in low light, but at intermediate light levels its activity was dependent on the irradiance. O2 concentration had no effect on the promoter activity, indicating that photorespiratory metabolites are not triggering the response. The availability of cells transformed with a CO2-regulated reporter gene should facilitate further studies on the metabolic adaptations that occur in some green algae in response to the external CO2 level.

Animals↗
PubMed1997

Molecular cloning and biochemical characterization of carbonic anhydrase from Populus tremula x tremuloides.

A leaf cDNA library from hybrid aspen, Populus tremula x tremuloides, was constructed. From this two different cDNA clones, denoted CA1a and CA1b, encoding a chloroplastic carbonic anhydrase (CA) were isolated and DNA sequenced. Analysis of the deduced amino acid sequences showed that the isolated CAs belong to the beta-CA family, and have identities around 70% to other dicotyledonous plant CAs. The two hybrid aspen cDNA clones display a high nucleotide sequence identity, only 12 nucleotides differ. Since only one gene copy of this soluble chloroplastic CA is present in the nuclear genome, we postulate that the two isolated cDNA clones are alleles. Northern blot hybridization revealed a CA transcript of ca. 1300 bases, 140 bases shorter than in pea. Western and northern blot hybridizations on crude protein extracts and on total RNA, respectively, isolated from stem and leaves, showed that hybrid aspen CA is expressed specifically in the leaf under the growth conditions used. Based on the deduced amino acid sequence, the mature hybrid aspen CA enzyme subunit has a molecular mass of 24.8 kDa. The enzyme was over-expressed in Escherichia coli, and purified by affinity chromatography. Biochemical characterization showed that the protein structure and the CO2-hydration activity are similar to the pea enzyme. Molecular characterization of a CA from a perennial plant has not previously been performed, and it demonstrates that both the structure and activity of hybrid aspen CA resembles CAs from annual plants.

Amino Acid Sequence↗
PubMed1997

Blood pressure in relation to medical, psychological and social variables in a population of 80-year-olds. Survival during 6 years.

OBJECTIVES: To relate elevated blood pressure in 80-year-olds to symptoms, life satisfaction and survival. DESIGN: Examinations of medical, psychological and social factors every year between 80 and 86 years of age. SETTING: Primary health care in the city of Lund in southern Sweden. SUBJECTS: Three-hundred and thirty-three persons living in the city of Lund and born in 1908. Participation rate was 67%. INTERVENTION: Abnormal findings were further examined and treated. MAIN OUTCOME MEASURES: Symptoms, blood pressure, laboratory values, psychological factors, cognition, living conditions, and survival. RESULTS: Hypertension according to the definition used was found in 70%. Women were over-represented (P < 0.05). Amongst persons with alleged hypertension, diuretics (P < 0.001) and 'other cardiovascular drugs' (P < 0.001) were more often used. Analgesics were more often used amongst assessed hypertensives (P < 0.05). Those with assessed hypertension scored better in testing of cognition compared to nonhypertensives (P < 0.05), and less often lived in institutions (P < 0.001). Assessed hypertensives had a better survival than alleged hypertensives during the following 7 years (P < 0.01). CONCLUSIONS: Eighty-year-olds with assessed hypertension in the consulting room showed fewer symptoms and had a better cognition and survival than alleged hypertensives (those with a history of hypertension).

Aged↗
PubMed1997

The Swedish Centenarian Study: a multidisciplinary study of five consecutive cohorts at the age of 100.

UNLABELLED: Centenarians born 1887-91, who lived in southern Sweden were asked to participate in this multidisciplinary study (N = 164). Of the survivors (N = 143), 70 percent agreed (N = 100). The purpose was to describe the population from physical, social, and psychological points of view; to characterize centenarians with various health conditions and diverse degrees of autonomy and life satisfaction; and to identify factors at 100 years that predict future survival. RESULTS: Eighty-two percent were women, 25 percent lived in their own home, 37 percent in old age homes, and 38 percent in nursing homes. Socioeconomic status showed a similar distribution compared to nationally representative data. Fifty-two percent managed activities of daily living with or without minor assistance. The incidence of severe diseases was low. In 39 percent a disorder of the circulatory system was found. Thirty-nine percent (women) and 11 percent (men) had had at least one hip fracture. Twenty percent had good hearing and good vision. Twenty-seven percent were demented according to DSM III-R criteria. Means on cognitive tests (word-list, digit-span, learning, and memory) were lower compared to seventy to eighty year old groups. The variation in performance was extremely widespread. Personality profiles (MMPI) indicated that the centenarians were more responsible, capable, easygoing and less prone to anxiety than the population in general. Extensive neuropathological investigation revealed no major diseases or large lesions but mild through multiple changes. RESULTS suggest that centenarians are a special group genetically. A causal structure model emphasized body constitution, marital status, cognition and blood pressure as particularly important determinants for survival after 100 years.

Aged↗
PubMed1996

A cDNA coding for glutathione S-transferase from the unicellular green algae Coccomyxa sp.

A cDNA coding for glutathione S-transferase (GST) was cloned and sequenced from the unicellular green algae Coccomyxa sp. The predicted 215 amino acid polypeptide (23.9 kDa, pI 5.3) is most similar to the theta-type GSTs found in a variety of different eukaryotic organisms. Within this sub-class, the Coccomyxa GST is 42% identical (63% similar) to the flatfish Pleuronectes platessa homologue, and 24 to 35% (49-57%) to other theta-type GST's.

Amino Acid Sequence↗
PubMed1996

Discovery of an algal mitochondrial carbonic anhydrase: molecular cloning and characterization of a low-CO2-induced polypeptide in Chlamydomonas reinhardtii.

In green unicellular algae, several polypeptides are induced upon exposure to limiting CO2. We report here on the localization and characterization of one of these, a 22-kDa polypeptide in Chlamydomonas reinhardtii. This nuclear-encoded polypeptide is induced in the mitochondria by a lowering of the partial pressure of CO2 in the growth medium from 5% to air CO2 levels. Sequencing of two different cDNA clones coding for the polypeptide identified it as a 20.7-kDa beta-type carbonic anhydrase (CA; carbonate dehydratase, carbonate hydro-lyase, EC 4.2.1.1). The two clones differ in their nucleotide sequences but code for identical proteins, showing that this CA is encoded by at least two genes. Northern blot hybridization reveals that mRNA transcripts are only present in cells transferred to air CO2 levels. A comparison of the deduced amino acid sequence with those of other beta-CAs shows the largest degree of similarity with CA from the cyanobacterium Synechocystis (50% identity and 66% similarity). To our knowledge, this is the first identification and characterization of a mitochondrial CA from a photosynthetic organism.

Amino Acid Sequence↗