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Biomedical subjects

T Gustafsson

Publications and source records attributed to T Gustafsson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Synthesis of a C-glycoside analogue of beta-D-galactosyl hydroxynorvaline and its use in immunological studies.

A C-linked isostere of beta-D-galactosylated hydroxynorvaline has been prepared in eight steps from per-O-benzylated galactopyranolactone. Addition of a homoallylic Grignard reagent to the lactone, reduction of the resulting hemiacetal with triethylsilane, and a Wittig reaction with Garner's aldehyde were key steps in this synthesis. The C-linked building block was then incorporated at position 264 into the fragment CII(256--270) from typeII collagen by solid-phase synthesis using a combination of the tert-butoxycarbonyl (Boc) and 9-fluorenylmethoxycarbonyl (Fmoc) protective group strategies. Deprotection of the benzylated C-linked galactosyl moiety was achieved simultaneously with cleavage of the glycopeptide from the solid phase by using triethylsilyl trifluoromethanesulfonate in TFA. Helper T-cell hybridomas obtained in a mouse model for rheumatoid arthritis responded to the C-linked glycopeptide when presented by classII MHC molecules. However, 10- to 20-fold higher concentrations were required as compared to when O-linked beta-D-galactosylated hydroxynorvaline or hydroxylysine (Hyl) were present at position 264 of CII(256--270). Thus, replacement of a single oxygen atom by a methylene group in the carbohydrate moiety of a glycopeptide antigen had a substantial influence on the T-cell response. This reveals that T cells are able to recognize the carbohydrate moiety of glycopeptide antigens with high specificity. Finally, the results suggest that structural modifications of beta-D-Gal-Hyl(264) in CII(256--270) may give altered peptide ligands that can be used for induction of tolerance in autoimmune rheumatoid arthritis.

Animals↗
PubMed2000

X-ray study of deformation density and spontaneous polarization in ferroelectric NaNO2

The deformation electron density of ferroelectric sodium nitrite has been determined from X-ray diffraction data at 30 K, using Hirshfeld deformation functions. Owing to the strong correlation between odd terms of the deformation coefficients, constraints were imposed in the refinement. The net charges for Na, N and O atoms were estimated to be 0.27, 0.20 and -0.24 e, respectively. The calculated spontaneous polarization using these net charges and atomic dipole terms, 7.8 microC cm(-2), is much closer to the recently measured value, 12 microC cm-2, as compared with the value calculated from the formal point charges (74 microC cm(-2)).

Journal Article↗
PubMed1999

Effect of alpha-trinositol on interstitial fluid pressure, oedema generation and albumin extravasation in experimental frostbite in the rat.

1. The anti-inflammatory effect of alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate) on oedema formation, microvascular protein leakage and interstitial fluid pressure (Pif) in rat skin after frostbite injury, was investigated. Alpha-trinositol (40 mg kg body weight(-1)) was administered intravenously as a bolus both before and/or in the interval between freezing and thawing of the tissue. 2. Pif was measured in rat paw skin with micropipettes connected to a servo-controlled counterpressure system. Oedema formation was estimated by measuring the increase in total tissue water content (wet weight minus dry weight divided by dry weight). Albumin extravasation (i.e., the difference between the plasma equivalent space for 125I- and 131I-human serum albumin (HSA) circulating for different time intervals) was used to estimate the microvascular leakage. 3. Compared to untreated animals, alpha-trinositol given pre- and/or post-freeze reduced total tissue water and albumin extravasation as well as the fall in Pif in injured tissue significantly (P<0.05). Alpha-trinositol given only post-freeze reduced total tissue water and albumin extravasation from 4.46+/-0.93 and 2.37+/-1.12 to 2.51+/-0.29 and 0.36+/-0.18 ml g dry weight(-1), respectively (P<0.05). 4. Pif fell from -0.8+/-0.2 mmHg pre-freeze to -3.4+/-1.0 mmHg (P<0.05) at 20 min after tissue injury (circulatory arrest) and was attenuated by treatment with alpha-trinositol. 5. We conclude that alpha-trinositol exerts its anti-oedematous effect by acting on the extracellular matrix, attenuating the lowering of Pif as well as on the microvascular wall, thereby decreasing the protein extravasation.

Animals↗
PubMed1999

Exercise-induced expression of angiogenesis-related transcription and growth factors in human skeletal muscle.

mRNA expression of vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), and hypoxia-inducible factor (HIF) subunits HIF-1alpha and HIF-1beta in human skeletal muscle was studied during endurance exercise at different degrees of oxygen delivery. Muscle biopsies were taken before and after 45 min of one-legged knee-extension exercise performed under conditions of nonrestricted or restricted blood flow (approximately 15-20% lower) at the same absolute workload. Exercise increased VEGF mRNA expression by 178% and HIF-1beta by 340%, but not HIF-1alpha and FGF-2. No significant differences between the restricted and nonrestricted groups were observed. The exercise-induced increase in VEGF mRNA was correlated to the exercise changes in HIF-1alpha and HIF-1beta mRNA. The changes in VEGF, HIF-1alpha, and HIF-1beta mRNAs were correlated to the exercise-induced increase in femoral venous plasma lactate concentration. It is concluded that 1) VEGF but not FGF-2 gene expression is upregulated in human skeletal muscle by a single bout of dynamic exercise and that there is a graded response in VEGF mRNA expression related to the metabolic stress and 2) the increase in VEGF mRNA expression correlates to the changes in both HIF-1alpha and HIF-1beta mRNA.

Adult↗
PubMed1999

Interaction of angiotensin II and the insulin-like growth factor system in vascular smooth muscle cells.

We studied the effects and interactions of ANG II and the insulin-like growth factor (IGF) system in cultured rat aortic smooth muscle cells. ANG II (1 microM) and IGF-I (10 nM) stimulated both DNA and protein synthesis. The effects of the two peptides in combination were additive or more than additive. The AT(1) receptor antagonist losartan (10 and 100 microM) blocked their synergistic effect on DNA synthesis. IGF binding protein (IGFBP)-1 inhibited the effect of IGF-I but not that of ANG II on DNA synthesis. IGF-I stimulated gene expression of IGFBP-2 and IGFBP-4. ANG II decreased IGF-I, IGFBP-2, and IGFBP-4 transcripts but increased the IGF-I receptor transcript. IGF-I and ANG II in combination had similar effects on gene expression as ANG II alone. The IGFBP-2 and IGFBP-4 peptides could be detected in the conditioned medium. Our results show that ANG II and IGF-I have synergistic effects on vascular smooth muscle cells and that they interact in several ways.

Angiotensin II↗
PubMed1999

Different inhibitory actions of IGFBP-1, -2 and -4 on IGF-I effects in vascular smooth muscle cells.

IGF-I is involved in the regulation of metabolism, growth and migration of vascular smooth muscle cells (VSMCs). We have studied how IGFBP-1, -2 and -4 modulate IGF-I-induced DNA and protein synthesis in cultured rat VSMCs. DNA and protein synthesis were measured as incorporation of [3H]thymidine and [3H]leucine into DNA and protein respectively. Western immunoblot was used to detect IGFBPs in conditioned medium and solution hybridization was used to measure IGFBP gene expression. IGF-I stimulated DNA synthesis with an EC50 of 44 pM, reaching a maximal effect at 1 nM. An IGF-I concentration of 1 nM was subsequently used in the experiments with IGFBPs. IGFBP-1 and IGFBP-4 acted in an inhibitory manner on IGF-I-induced DNA synthesis with calculated IC50 values of 1.6 nM and 6.2 nM respectively. IGFBP-2 (16 nM) also inhibited the growth response to IGF-I, but this effect could only be obtained if the two peptides were pre-incubated together for 2 h prior to addition to the cells. IGFBP-1, -2 and -4 inhibited IGF-I-induced protein synthesis in a similar way. Immunoblot of the incubation medium showed little degradation of IGFBP-2 and -4 for up to 24 h. mRNA for IGFBP-2 and -4, but not for IGFBP-1 was detected in the VSMCs. Endogenous IGFBP-2 and -4 could be detected by immunoblot in the conditioned medium but only if it was concentrated. In conclusion, IGFBP-1, -2 and -4, of which IGFBP-2 and -4 may be locally derived, act as inhibitors with different potencies on IGF-I effects in VSMCs.

Animals↗
PubMed1999

Insulin-like growth factor binding proteins-2 to -6 are expressed by human vascular smooth muscle cells.

We have investigated the expression and secretion of insulin-like growth factor binding proteins (IGFBPs-1 to -6) in human vascular smooth muscle cells (hVSMCs) cultured from human renal arteries. Solution hybridization was used to determine IGFBP mRNA levels and Western immunoblot to detect the corresponding peptides. The hVSMCs expressed mRNAs for IGFBPs-2 to -6; IGFBP-1 mRNA was not detected. IGFBPs-3, -4 and -6 mRNAs were the most abundant, IGFBP-5 was also highly expressed, whereas the IGFBP-2 mRNA was just above the limit of detection. Serum starvation for 48 h significantly decreased the mRNA levels of IGFBPs-2 to -5 and tended to decrease IGFBP-6 mRNA also. IGFBPs-2, -4, -5 and -6 peptides could be detected in conditioned medium, but IGFBP-3 peptide was not detected. IGFBP-4 was the only peptide detected without any concentration step. Low-molecular-mass immunoreactive degradation products were found for IGFBPs-2 and -4. Exogenous IGFBPs-1, -3 and -4 in concentrations of 50 ng/ml inhibited DNA synthesis induced by 1 nM IGF-I, whereas IGFBPs-2, -5 and -6 had no significant inhibitory effects at this concentration. We conclude from these results that all IGFBPs except IGFBP-1 are expressed in hVSMC. Our results indicate that locally produced, in addition to circulating, IGFBPs may have an important role in the regulation of hVSMC.

Blotting, Western↗
PubMed1998

Substrate availability limits human skeletal muscle oxidative ATP regeneration at the onset of ischemic exercise.

We have demonstrated previously that dichloroacetate can attenuate skeletal muscle fatigue by up to 35% in a canine model of peripheral ischemia (Timmons, J.A., S.M. Poucher, D. Constantin-Teodosiu, V. Worrall, I.A. Macdonald, and P.L. Greenhaff. 1996. J. Clin. Invest. 97:879-883). This was thought to be a consequence of dichloroacetate increasing acetyl group availability early during contraction. In this study we characterized the metabolic effects of dichloroacetate in a human model of peripheral muscle ischemia. On two separate occasions (control-saline or dichloroacetate infusion), nine subjects performed 8 min of single-leg knee extension exercise at an intensity aimed at achieving volitional exhaustion in approximately 8 min. During exercise each subject's lower limbs were exposed to 50 mmHg of positive pressure, which reduces blood flow by approximately 20%. Dichloroacetate increased resting muscle pyruvate dehydrogenase complex activation status by threefold and elevated acetylcarnitine concentration by fivefold. After 3 min of exercise, phosphocreatine degradation and lactate accumulation were both reduced by approximately 50% after dichloroacetate pretreatment, when compared with control conditions. However, after 8 min of exercise no differences existed between treatments. Therefore, it would appear that dichloroacetate can delay the accumulation of metabolites which lead to the development of skeletal muscle fatigue during ischemia but does not alter the metabolic profile when a maximal effort is approached.

Acetylcarnitine↗
PubMed1998

Topical D-myo-inositol-1,2,6-trisphosphate and hexylbetaine treatment reduces albumin extravasation in experimental rat skin burn injury.

The anti-inflammatory agent D-myo-inositol-1,2,6-trisphosphate (1,2,6-IP3) has shown beneficial effects in experimental burns following systemic administration. The purpose of this study was to investigate the effect of topical 1,2,6-IP3 cream on a standardised full-thickness 1 cm2 burn injury in rats. The experimental cream contained a transcutaneous absorption enhancer, hexylbetaine. Five different treatment groups were used. Two experimental groups of burned rats received either 1,2,6-IP3 cream with hexylbetaine (n = 10) or without hexylbetaine (n = 10). Two burned control groups were treated either with hexylbetaine cream (n = 10) or placebo cream (n = 10), while a third control group was untreated (n = 14). The various creams (0.5 g) were administered to the experimental burn area and allowed to remain for 3 h covered with an occlusive dressing. Spectrophotometrical quantification of Evans blue albumin extravasation was used to evaluate the effect of the experimental creams on vascular permeability following the burn trauma. Results showed a significant reduction of albumin extravasation both by 1,2,6-IP3 (p<0.05) and by hexylbetaine alone (p<0.01), as compared to placebo cream-treated animals. The transcutaneous absorption enhancer hexylbetaine did not further improve the effect of 1,2,6-IP3 on burn oedema. In conclusion, both topical 1,2,6-IP3 and hexylbetaine induced a significant reduction of albumin extravasation in burned skin. The effect of 1,2,6-IP3 could be related to previously shown anti-inflammatory actions of the agent, while the mechanisms of actions of hexylbetaine remain to be investigated.

Administration, Topical↗
PubMed1998

Muscle acetyl group availability is a major determinant of oxygen deficit in humans during submaximal exercise.

The delay in skeletal muscle mitochondrial ATP production at the onset of exercise is thought to be a function of a limited oxygen supply. The delay, termed the oxygen deficit, can be quantified by assessing the above baseline oxygen consumption during the first few minutes of recovery from exercise. During submaximal exercise, the oxygen deficit is reflected by the extent of muscle phosphocreatine (PCr) breakdown. In the present study, nine male subjects performed 8 min of submaximal, single leg knee extension exercise after saline (Control) and dichloroacetate (DCA) infusion on two separate occasions. Administration of DCA increased resting skeletal muscle pyruvate dehydrogenase complex activation status threefold (Control = 0.4 +/- 0.1 vs. DCA = 1.3 +/- 0.1 mmol acetyl-CoA.min-1.kg wet muscle-1 at 37 degrees C, P < 0.01) and elevated acetylcarnitine concentration fivefold (Control = 2.2 +/- 0.5 vs. DCA = 10.9 +/- 1.2 mmol/kg dry mass, P < 0.01). During exercise, PCr degradation was reduced by approximately 50% after DCA (Control = 33.2 +/- 7.1 vs. DCA = 18.4 +/- 7.1 mmol/kg dry mass, P < 0.05). It would appear, therefore, that in humans acetyl group availability is a major determinant of the rate of increase in mitochondrial respiration at the onset of exercise and hence the oxygen deficit.

Acetylation↗