Biomedical subjects

K Berg

Publications and source records attributed to K Berg.

At least 199 records · Page 11Linked to original sources

PubMed1995

Evaluation of body composition by dual energy x-ray absorptiometry and two different software packages.

Dual energy x-ray absorptiometry (DXA) measures body composition, tissue distribution, bone mineral content (BMC), and bone mineral density (BMD). Differences are possible due to software versions. This investigation examined body composition, tissue distribution, BMC, and BMD measurements using a DXA (Lunar Corp., Madison, WI) with different software packages (versions 3.4 and 3.6R). Fifteen women, ages 20-40 yr, enrolled in a weight-loss study (body mass index = 28) and volunteered for body composition assessment by densitometry. BMC, BMD, and tissue distribution measurements were made using DXA. Results were analyzed once each with software versions 3.4 and 3.6R. BMC + total soft tissue, measured using DXA, was comparable to measured body weight (3.4 = 76.3 kg; 3.6R = 76.5 kg; weight = 76.5 kg). Lower BMC and BMD (5.5% and 1.8%, P < 0.01) were observed with 3.6R. Arm tissue mass was lower (1,530 g; P < 0.01) and fat declined (1,069 g; P < 0.01) with 3.6R. Leg tissue mass decreased 487 g (P < 0.01), but fat tissue increased (526 g, P < 0.01) with 3.6R. A larger fat mass (1,492 g) and lower lean mass (1,115 g) were observed with 3.6R compared with 3.4. Percent fat values by densitometry using DXA 3.4 and 3.6R were 38.1%, 39.9, and 41.9%, respectively. These results demonstrated differences in total body composition, lean and fat tissue distribution, and bone measurements from DXA software versions.

Absorptiometry, Photon↗

PubMed1995

The Balance Scale: reliability assessment with elderly residents and patients with an acute stroke.

The objective of this study was to assess the reliability of the Balance Scale. Subjects were chosen from a larger group of 113 elderly residents and 70 stroke patients participating in a psychometric study. Elderly residents were examined at baseline, and at 3, 6 and 9 months, and the stroke patients were evaluated at 2, 4, 6 and 12 weeks post onset. The Cronbach's alphas at each evaluation were greater than 0.83 and 0.97 for the elderly residents and stroke patients respectively, showing strong internal consistency. To assess inter-rater reliability, therapists treating 35 stroke patients were asked to administer the Balance Scale within 24 hours of the independent evaluator. Similarly, caregivers at the Residence were asked to test the elderly residents within one week of the independent evaluator. To assess intra-rater reliability, 18 residents and 6 stroke patients were assessed one week apart by the same rater. The agreement between raters was excellent (ICC = 0.98) as was the consistency within the same rater at two points in time (ICC = 0.97). The results support the use of the Balance Scale in these groups.

Acute Disease↗

PubMed1994

Psychiatric genetic research at the National Institute of Mental Health.

For some time it has been known through the results of family, twin, and adoption studies that heredity appears to play a significant causal role in many mental disorders, including schizophrenia, bipolar disorder, and other mood disorders, Alzheimer's Disease, panic disorder, obsessive compulsive disorder, autism, dyslexia, and Tourette's Syndrome. The precise patterns of inheritance of these complex disorders have not been determined, nor have the relevant genes been localized or cloned. Because the genetics are complex and because there is also clearly an environmental contribution to behavior, we expect the analysis of the genetics of mental illness to be arduous, and not quickly resolved. There are several compelling reasons to continue to focus our attention on uncovering the genetic factors for severe mental illness. Prominent among these are the implications for better treatment of mental disorders. The National Institute of Mental Health supports a wide range of studies on psychiatric genetic research.

Brain Diseases↗

PubMed1994

Lysosomes as photochemical targets.

Sulfonated tetraphenyl porphines (TPPSn) are photosensitizing dyes that localize in lysosomes of NHIK 3025 cells. In order to elucidate the mechanisms of cell inactivation by photochemical treatment with TPPSn, lysosomal enzyme inactivation and release of lysosomal contents were examined after treatment. In cells treated with TPPS4 and light, the lysosomal enzymes beta-N-acetyl-D-glucosaminidase (beta-AGA) and cathepsin(L+B) were almost completely inactivated and no enzyme activities were released from the lysosomes. In contrast, a maximum of 30 and 50% of the initial beta-AGA activity was released from lysosomes after treatment with TPPS1 and TPPS2a, respectively. Forty per cent of the initial beta-AGA activity was released after treatment with TPPS2a and a non-cytotoxic dose of light. After such a treatment only approximately 10% of the initial cathepsin activity was found in the cytosol fraction and in all other cases no cathepsin activity was recovered in the cytosol fraction after photochemical treatment. It was found that the constituents of the cytosol partly inhibited cathepsin activity. This inhibitory effect was not influenced by the photochemical treatment, neither was the colony-forming ability of photochemically treated cells influenced by pre-treatment with the cathepsin inhibitor E64. The present results indicate that NHIK 3025 cells are not killed by lysosomal disruption after photochemical treatment. This is partly due to photochemical inactivation of the lysosomal enzymes and to the action of cytosolic cysteine cathepsin inhibitors. The present results also indicate that cells can survive a partial lysosomal disruption.

Acetylglucosaminidase↗

PubMed1994

Influence of serum lipoprotein(a) and homocyst(e)ine levels on graft patency after coronary artery bypass grafting.

High serum levels of lipoprotein(a) and homocyst(e)ine are considered independent risk factors for atherothrombotic disease. In a prospective study in patients undergoing coronary artery bypass grafting, the preoperatively determined lipoprotein(a) and homocyst(e)ine levels were related to the frequency of 1-year graft occlusion. A cohort of 610 patients who underwent coronary artery bypass surgery was followed through the first postoperative year. Shunt angiography was performed in 581 patients (95%) at a mean of 12.1 +/- 1.5 months after the operation. The serum levels of lipoprotein(a) (n = 570) and homocyst(e)ine (n = 565) in patients with occluded internal mammary artery (IMA) grafts were not significantly different from the levels in those with open IMA grafts. Also, the serum lipoprotein(a) and homocyst(e)ine levels in patients with > or = 1 occluded vein graft were not significantly different from those in patients with all vein grafts patent. This study also determined the incidence of graft occlusion in quartiles of the lipoprotein(a) and homocyst(e)ine levels, respectively, and tested for linear trends. No significant trends in the incidence of graft occlusion were found, but the number of patients with vein graft occlusions was higher in the lowest quartile of lipoprotein(a) than that in the upper 3 quartiles (odds ratio, 1.82, 95% confidence interval, 1.21 to 2.74, p = 0.0025). Controlling for background variables in multivariate models only slightly modified the results. Thus, apart from an unexplained excess of vein graft occlusions in the lowest quartile of lipoprotein(a) levels, no association between the preoperative serum lipoprotein(a) or homocyst(e)ine levels and the frequency of 1-year graft occlusion could be demonstrated.

Aged↗

PubMed1994

Sulfonated aluminium phthalocyanines as sensitizers for photochemotherapy. Effects of small light doses on localization, dye fluorescence and photosensitivity in V79 cells.

V79 cells incubated with di- or tetrasulfonated aluminium phthalocyanines (AlPcS2 or AlPcS4) showed a granular fluorescence pattern. Co-staining with the lysosomotropic dye acridine orange (AO) indicated that the granules that were stained by these photoactive phthalocyanines were identical to lysosomes. Small light exposures made the lysosomes permeable to the dyes without inactivating the cells. Also, the lysosomal enzymes beta-AGA and cathepsin (L+B) were inactivated by small light exposures when AlPcS4 was present. Such small and almost nontoxic light exposures caused a redistribution of the dyes in the cells that was accompanied by a more than 10-fold increase in the fluorescence quantum yields of the dyes. Surprisingly, this redistribution and increase in fluorescence did not result in any significant increase in the photosensitivity of the cells.

Acetylglucosaminidase↗

PubMed1994

Evaluation of a new photosensitizer, meso-tetra-hydroxyphenyl-chlorin, for use in photodynamic therapy: a comparison of its photobiological properties with those of two other photosensitizers.

The properties of a new photosensitizer, meso-tetra-hydroxyphenyl-chlorin (mTHPC), were studied using V79 cells (Chinese-hamster lung fibroblasts). Comparisons were made with 2 other photosensitizers: photofrin II (PII) and meso-tetra-hydroxyphenyl-porphyrin (mTHPP). A main advantage of mTHPC is that it has a strong absorption at 652 nm. Maximal cellular uptake of the dye was observed after 24 hr incubation of the cells with the drug. Using a confocal laser-scanning fluorescence microscope, we observed a diffuse distribution of mTHPC in the cytoplasm. Furthermore, the lipophilicity of mTHPC was compared with that of the components of PII by means of high-pressure liquid chromatography (HPLC). Absorption and fluorescence spectroscopy indicated that aggregated as well as monomeric mTHPC was bound to the cells. The action spectrum for photo-inactivation of the cells showed that aggregated mTHPC did not contribute significantly to its photosensitizing effects. In the present cellular system, the efficiency of photodynamic therapy (PDT) with mTHPC (cells were irradiated at a wavelength of 652 nm) was higher than with PII (irradiation at 630 nm) or with mTHPP (648 nm). The quantum yield for photo-inactivation of cells was smaller for mTHPC than for mTHPP and PII. The addition of 1,3-diphenylisobenzofuran (DPBF) reduced cell inactivation during PDT. Thus, PDT with mTHPC seems to act at least partly via a type-II process.

Animals↗

PubMed1994

[Occupational and individual risk factors of muscular pain].

It is suggested that occupational exposure to muscle load should be described by three factors to indicate health risks: level, repetitiveness and duration. A reduction in level is beneficial if the level is high (> 10-15% MVC). However, even a low level involves risk of musculoskeletal complaints if the exposure is repetitive. A reduction of the occupational exposure from 7-8 hours to 4-5 hours per day delays the development of musculoskeletal complaints, but does not provide long-term reduction of risk with frequent repetitions. When interventions are carried out to reduce the risk of occupational musculoskeletal complaints, it is necessary to consider psychosocial and individual constitutional factors in addition to the three factors constituting the occupational exposure to muscle load.

Biomechanical Phenomena↗

PubMed1994

Characterization of singlet oxygen-induced guanine residue damage after photochemical treatment of free nucleosides and DNA.

DNA and free nucleosides were photosensitized with the DNA-binding dyes methylene blue (MB) and meso-tetra(4-N-methyl-pyridyl) porphyrin (p-TMPyP) and the non-binding meso-tetra (4-sulphonatophenyl) porphyrin (TSPP). After light exposure DNA was enzymatically digested to nucleosides. Only the guanine residues were photodegraded. By measuring optical absorption, at least 20 photoproducts were detected. Singlet oxygen (1O2) was involved in induction of all these products since D2O enhanced their yields from 4 to 10 times. The photoproducts were the same for all sensitizers. However, several photoproducts were found only with DNA or only with free 2'-deoxyguanosine. Four of 20 photoproducts were induced both in DNA and free 2'-deoxy-guanosine. The yield of the photoproduct 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) relative to the degree of 2'-deoxy-guanosine degradation depended on which sensitizer was used and on whether nucleosides or DNA was exposed. Apparently, DNA structure affected the types of as well as the yields of photo-products induced by 1O2.

DNA↗

PubMed1994

Oestrogen receptor (ESR) polymorphisms and breast cancer susceptibility.

The allele frequencies of three restriction fragment length polymorphisms at the oestrogen receptor (ESR) locus were compared between breast cancer patients and controls. Leucocyte or tumour DNA from 238 and 122 patients, respectively, and leucocyte DNA from 672 controls was analysed. Alleles having the XbaI restriction site detected by the M72 probe (covering exon 2 and flanking introns) were significantly more frequent in patients than in controls (P = 0.033). Within the breast cancer population, the presence of the XbaI restriction site was associated with late onset of the disease but this association was only of borderline significance. The allele frequencies of the BstUI polymorphism in exon 1 and the PvuII polymorphism in intron 1 did not differ between cases and controls. However, alleles with the PvuII restriction site were more frequent in patients with progesterone receptor negative primary tumours than in patients with progesterone receptor positive primary tumours (P = 0.027). There was no significant association between any of the ESR polymorphisms and the oestrogen receptor status of the primary tumours. The results indicate that the ESR gene or a gene closely linked to it is involved in the development of at least a subset of breast carcinomas.

Adult↗

PubMed1994

The use of a water-soluble formazan complex to quantitate the cell number and mitochondrial function of Leishmania major promastigotes.

One of the methods to quantitate Leishmania major promastigotes (LmP) has been to utilize the formation of a formazan dye, which in turn is produced via conversion of an artificial substrate, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The method has one major drawback in that the formazan complex precipitates inside the parasites and has to be extracted by denaturants before measurements can be performed. By using a new synthetic substrate, 3-(4,5-dimethylthiazol-2-yl)-5- (3-carboxymethoxyphenyl)-2-(4-sulfonyl)-2H-tetrazolium (MTS), the extraction procedure is eliminated as the formazan-like dye is released spontaneously into the medium, making it possible to perform several measurements on the same parasite culture without disturbing or killing the parasites. The measurements were shown to reflect the numbers of parasites as confirmed via comparative experiments using radioactive thymidine uptake and cell counting, respectively. The method is simple, fast, and highly reproducible and is suitable for drug screening, identification of drug-resistant isolates, and growth-kinetics studies. It is therefore contemplated that the MTS method will be a general and useful technique in this field of parasitology.

Animals↗

PubMed1994

Lp(a) lipoprotein: an overview.

The Lp(a) lipoprotein, a distinct class of serum lipoproteins, was detected in 1962. It consists of an LDL particle to which a long polypeptide chain is attached by a disulfide bridge. The level of Lp(a) lipoprotein is genetically determined. Single locus control was suggested already in the very first report, and this has been conclusively confirmed by the demonstration of absolute genetic linkage to the plasminogen gene, from which the LPA gene is likely to have evolved. The detection in 1974 of an association between Lp(a) lipoprotein and coronary heart disease has been confirmed in numerous studies. The Lp(a) lipoprotein may have atherogenic as well as thrombogenic properties and thus form the bridge between atherogenesis and thrombogenesis. Genes determining a moderate level of Lp(a) lipoprotein may be longevity genes, and it seems possible that Lp(a) lipoprotein, because of its affinity to vessel walls, may also influence placental function. Lp(a) lipoprotein measurements should be included in the diagnostic work-up of people with premature coronary heart disease or with such disease in close relatives.

Animals↗

PubMed1994

Effects of ultraviolet radiation on intercellular communication in V79 Chinese hamster fibroblasts.

The effects of ultraviolet (UV) radiation on gap junctional intercellular communication (GJIC) in V79 Chinese hamster fibroblasts were studied by means of a dye transfer assay. Intercellular communication was shown to be altered by UVB (297/302 nm) and UVA (365 nm) radiation, the effect depending on the wavelength of exposure and time between irradiation and microinjection of the dye in the dye transfer assay. Exposure to 297/302 nm radiation induced a reduction in intercellular communication 6 min after exposure. Incubation of the cells post-irradiation reversed the inhibition of GJIC. From 2 to 24 h after exposure an increase in GJIC over the control cells was seen, with a maximum at 8 h post-irradiation. UVA (365 nm) radiation, on the other hand, induced an increase in the intercellular communication 6 min after irradiation. Incubation of the cells post-irradiation led to a decrease in the number of communicating cells, with a minimum seen 4 h after exposure. The reduction in communication observed after exposure to UVB and UVA was not correlated with similar modifications in the gap junction protein connexin43 as found when exposing the cells to the tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate. For the higher fluences of UVA, a decrease in immunorecognizable connexin43 was seen, concomitant with a markedly increased background of higher mol. wt compounds. This may be due to UVA-induced crosslinking of connexin43. No correlation was found between changes in communication induced by UV radiation and levels of cyclic AMP.

Animals↗

PubMed1994

A long-term, randomized, comparative study of insulin versus sulfonylurea therapy in type 2 diabetes.

OBJECTIVES: To study the effect of insulin and sulfonylurea (SU) therapy on glycaemic control, insulin resistance and cardiovascular risk factors in type 2 diabetic subjects. DESIGN: A prospective, parallel, randomized, controlled, long-term study. SETTING: Outpatient clinic in tertiary referral centre. SUBJECTS: Thirty-six type 2 diabetic subjects treated with diet and SU, aged 44-69 years and a duration of diabetes of between 2 and 14 years. INTERVENTIONS: Individually adjusted doses of insulin and glibenclamide. MAIN OUTCOME MEASURES: Glycosylated haemoglobin (HbA1c), insulin resistance (euglycaemic glucose clamp), levels of lipids, lipoproteins and blood pressure. RESULTS: Glycaemic control improved during insulin treatment, but deteriorated on SU; HbA1c levels differed significantly between groups after 12 months of therapy (mean +/- SEM 7.9 +/- 0.3 vs. 9.5 +/- 0.4%, P = 0.004). Body mass index increased significantly during insulin treatment (26.4 +/- 0.7 to 27.8 +/- 0.7 kg/m2, P = 0.0001) and 30% of this increase was a result of an increase in lean body mass. The total glucose disposal rate showed a small increase in the insulin group. Levels of triglycerides and apolipoprotein B were significantly reduced during insulin treatment (1.8 +/- 0.2 to 1.5 +/- 0.2 mmol L-1, P = 0.03 and 1.58 +/- 0.1 to 1.40 +/- 0.08 g L-1, P = 0.003), and insulin prevented a reduction in the levels of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-1 and an increase in Lp(a) lipoprotein observed in the SU group. Blood pressure levels did not change during therapy. CONCLUSIONS: Insulin therapy was superior to SU treatment in achieving good metabolic control. Despite a modest improvement in cardiovascular risk factors in the insulin-treated group, no significant differences were observed between the groups after 1 year's treatment.

Aged↗

PubMed1994

No effect of insertion/deletion polymorphism at the ACE locus on normal blood pressure level or variability.

Angiotensin I-converting enzyme (ACE) cleaves angiotensin I to angiotensin II, which is the active component in the renin-angiotensin system (RAS). We have studied an insertion/deletion polymorphism in DNA at the ACE locus. In three different series comprising 140, 90 and 136 unrelated individuals we found no evidence of association between genotypes in this insertion/deletion (I/D) polymorphism and level of systolic or diastolic blood pressure. In two series of 130 and 88 monozygotic (MZ) twin pairs, respectively, there was no difference between genotypes in within-pair variation in systolic or diastolic blood pressure. Thus, in these series of healthy people, neither "level gene" nor "variability gene" effects of this insertion/deletion polymorphism were observed.

Adult↗

PubMed1994

The apolipoprotein B signal peptide insertion/deletion polymorphism is not associated with myocardial infarction in Norway.

The three-amino acid insertion/deletion (I/D) polymorphism in the apoB signal peptide (27 amino acid versus 24 amino acid signal peptide) was evaluated as a possible risk factor for myocardial infarction (MI) in a case-control study population comprising 238 MI survivors and 547 controls. In controls, homozygotes for the deletion allele (DD) had the highest mean levels of both total cholesterol and low density lipoprotein (LDL) cholesterol (LDLC), the homozygotes for the insertion allele (II) had the lowest mean values, while the heterozygotes (ID) had intermediate mean levels (p < 0.05). In MI survivors, the trend was similar, but only differences in mean LDLC levels were statistically significant (p < 0.05). No differences in genotype frequencies were detected between cases and controls in univariate analysis or in multivariate logistic regression analysis. Despite the results from the lipid analyses, we conclude that the I/D polymorphism in the apoB signal peptide is unlikely to be of major importance for MI risk in relatively young Norwegians.

Adult↗

PubMed1994

High Lp(a) lipoprotein level in maternal serum may interfere with placental circulation and cause fetal growth retardation.

We report on a woman with an Lp(a) lipoprotein level above the 99th centile of the population distribution of concentrations, who at the age of 43 had had deep vein thrombosis causing a pulmonary embolus and whose brother, who also had a very high level, had suffered a cerebral infarction at the age of 43. She had given birth to three children, all with very low birth weight, one of whom died when 3 months old. The placentas had been small and ischemic. The concurrence of a very high Lp(a) lipoprotein level, familial thromboembolic disease and recurrent placental ischemia with delivery of children with low birth weight suggests the possibility that a very high Lp(a) lipoprotein concentration may predispose to placental insufficiency, presumably arising from pathological changes in maternal uterine vessels in the placental bed. If confirmed, a very high Lp(a) lipoprotein level may be a factor to consider in women who have repeated pregnancies with placental insufficiency and who give birth to children with low birth weight.

Adult↗

PubMed1994

Confounding results of Lp(a) lipoprotein measurements with some test kits.

A small number of recent studies have reportedly failed to detect the well-established association between a high Lp(a) lipoprotein level and coronary heart disease (CHD). This has made some workers question the importance of a high Lp(a) lipoprotein level as a CHD risk factor. However, serious problems with some of the commercially available test kits, inadequate test techniques or failure to consider the lability of the Lp(a) lipoprotein particle are more plausible explanations of the confounding results. The problems with some of the commercially available test kits include lack of standardization and validation; risk of cross-reactivity with plasminogen or other serum proteins; failure to consider potential problems when measuring samples with varying length of the Lp(a) polypeptide chain (i.e. failure to cope with the isoform variation); non-divulgence of contents of test reagents; and pretreatments of samples that drastically change the Lp(a) lipoprotein particles from their native state. Any test system should be validated at the scientific level before it is assumed to provide correct measurements of Lp(a) lipoprotein level in serum. New test kits should be safely anchored in validation in one of the research laboratories active in the area, before they are put on the market. As new batches are produced, the quality of every new batch of test kits should be monitored on a long-term basis in collaboration with a research laboratory.

Confounding Factors, Epidemiologic↗