Cation-osmotic Haemolysis in Patients with Retinal Vein Occlusion

The purpose of this work was to use a new technique to assess erythrocyte deformability in patients with retinal vein occlusion. Erythrocyte microrheology changes were measured by cation-osmotic haemolysis (COH) in healthy donors and in patients with both central (n= 6) and branch (n= 16) retinal vein occlusion up to 12 months after the occlusion. The patient group consisted of five patients with ischaemic and 17 with oedematous vein occlusion. The control group consisted of the same number of age-, sex- and risk factor (hypertension)-matched donors. In patients with retinal vein occlusion, COH was significantly decreased compared to the control group. The decrease was most marked at low and high concentrations of incubating media where the differences reached high statistical significance (p<0.01–0.001). In our previous experiments we showed that COH and erythrocyte deformability (ED) are closely related and that COH reflects basic information about erythrocyte deformability. Thus, decreased COH in patients with retinal vein occlusion points to reduced ED in comparison with the control group. We, therefore, assume that impairment in ED together with other microrheological abnormalities contributes to the pathophysiology of changes in patients with retinal vein occlusion.     

Blood flow velocity,erythrocyte deformability and hepatic enzymes in heavy alcohol drinkers

Significantly decreased blood flow velocity in cerebral arteries, as well as decreased erythrocyte deformability, was found in heavy alcohol drinkers (Gdovinová 2002). The aim of this study was to determine if there is any correlation between the two. At the same time, the correlation between blood flow velocity and hepatic enzymes was also studied. The study group comprised 30 male patients, who were heavy alcohol drinkers, with a mean age of 46.4 years. Mean flow velocity (Vmean) was determined by a 2 MHz pulsed Doppler probe. Erythrocyte membrane biophysical properties were estimated by cation-osmotic haemolysis (COH). Hepatic enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyltransferase (GMT)] were measured in the Department of Biochemistry. The results were compared with the results from 20 healthy volunteers of the same age. Differences between the two groups were tested by Students t-test, and the relationship between blood flow velocity and COH, and of hepatic enzymes was analysed by regressive and correlative analysis. Results showed that Vmean was significantly decreased in heavy alcohol drinkers, in all cerebral arteries (the middle, anterior, and posterior cerebral arteries). No differences were noted between the left and right sides of the arteries tested. COH was similarly significantly decreased in heavy drinkers, in the medium of low (15.4 mmol/l NaCl) and high (123.2 mmol/l NaCl and above) ionic strength. Linear correlation between COH and Vmean was determined by correlative analysis, and a linear relationship was found. All hepatic enzymes (AST, ALT, GMT) were significantly increased in heavy drinkers. The relationship between Vmean and GMT was tested by the regressive analysis, and between these two parameters a linear relationship was found. It was concluded that changes in blood viscosity after the drinking of alcohol disturbs blood velocity and brain perfusion, which can be a major risk factor in strokes.     

Comparative Nuclear Magnetic Resonance Studies of Diffusional Water Permeability of Red Blood Cells from Different Species. XII. Dog (<Emphasis Type="BoldItalic">Canis familiaris</Emphasis>) and Cat (<Emphasis Type="BoldItalic">Felis domestica</Emphasis>)

The diffusional water permeability (P _d ) of dog and cat red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulphonate (PCMBS). The values of P _d were in the case of cat RBC ∼3.0 × 10⁻³ cm/s at 15 °C, 3.5 × 10⁻³ cm/s at 20 °C, 4.2 × 10⁻³ cm/s at 25 °C, 4.4 × 10⁻³ cm/s at 30 °C and 5.9 × 10⁻³ cm/s at 38 °C. In case of dog RBC the values of P _d were higher ∼3.8 × 10⁻³ cm/s at 15 °C, 4.6 × 10⁻³ cm/s at 20 °C, 5.0 × 10⁻³ cm/s at 25 °C, 5.9 × 10⁻³ cm/s at 30 °C and 7.9 × 10⁻³ cm/s at 37 °C. Systematic studies of the effect of PCMBS on water diffusion indicated that in the case of dog RBCs the maximal inhibition was reached in 15–30 min with 1 mm PCMBS, whereas in the case of cat RBCs in 60 min with 1 mm PCMBS or in 30 min with 2 mm PCMBS. The values of maximal inhibition in the case of cat RBC were in the range of 55–60% at 15 °C, 60–68% at 20 °C and 25 °C, 50–60% at 30 °C and 50–55% at 37 °C. In the case of dog RBC the corresponding values were higher, 75–80% at 15 °C, 70–80% at 20 °C and 25 °C, 65–70% at 30 °C and 55–60% at 37 °C. The basal permeability to water was estimated to be ∼1 × 10⁻³ cm/s −2 × 10⁻³ cm/s in the range of temperatures of 25–37 °C. The activation energy of water diffusion E _a,d was ∼19 kJ/mol for the dog RBC and ∼23 kJ/mol for the cat RBC. After incubation with PCMBS the values of E _a,d increased, reaching 40 kJ/mol in conditions of maximal inhibition of water exchange. The membrane polypeptide electrophoretic pattern of dog and cat RBCs has been compared with its human counterpart. Dog and cat RBCs contained higher amounts of spectrin (band 1 and 2) and lower amounts of bands 4.4, 4.2, band 5 and band 7 compared to human RBCs. Band 4.9 was decreased only in the cat RBCs, whereas band 6 was decreased only in the dog RBCs. Correspondence and offprint requests to: Gheorghe Benga, Department of Cell and Molecular Biology, ‘Iuliu Haţieganu’ University of Medicine and Pharmacy, 6 Pasteur St, 3400 Cluj-Napoca, Romania. Tel:/Fax: 40–64–194373; e-mail: GBenga@personal.ro; gbenga@umfcluj.ro     

Influence of muscle architecture on the torque and power–velocity characteristics of young and elderly men

This study investigated the contribution of muscle architecture to the differences in the torque–velocity and power–velocity relationships between older (OM n = 9, aged 69–82 years) and younger men (YM n = 15, aged 19–35 years). Plantarflexors’ (PF) maximal isometric and concentric torques were recorded at 0.87, 1.75, 2.62, 3.49 and 4.36 rad s⁻¹. Physiological cross-sectional area (PCSA) was calculated as the ratio of muscle volume (determined by magnetic resonance imaging) to muscle fascicle length (L _f, measured by ultrasonography). GM PCSA and L _f of the OM were, respectively, 14.3% (P < 0.05) and 19.3% (P < 0.05) smaller than of the YM. In the OM, GM maximum isometric torque and maximum contraction velocity (V _max), estimated from Hill’s equation were, respectively, 48.5 and 38.2% lower (P < 0.001) than in the YM. At all contraction velocities, the OM produced less torque than the YM (46.3% of YM at 0.87 rad s⁻¹ to 14.7% at 4.36 rad s⁻¹, P < 0.001). Peak power (PP) of the OM was 80% lower than that of the YM and normalisation of PP to muscle volume only reduced this difference by 10%. Normalisation of torque to PCSA reduced, but did not eliminate, differences in torque between YM and OM (9.6%) and differences in torque/PCSA increased with contraction velocity (P < 0.05). After normalisation of velocity to L _f, the difference in V _max between the OM and the YM was reduced to 15.9%. Thus, although muscle architecture contributes significantly to the differences in the torque– and power–velocity properties of OM and YM, other contractile factors, intrinsic to the muscle, seem to play a role. It is noteworthy that the deficit in PP between OM and YM is far greater than that of muscle torque, even after normalisation of PP to muscle volume. This finding likely plays an important role in the loss of mobility in old age.     

Dynamic force responses of skeletal muscle during stretch–shortening cycles

Muscle damage due to stretch–shortening cycles (i.e., cyclic eccentric/concentric muscle actions) is one of the major concerns in sports and occupational related activities. Mechanical responses of whole muscle have been associated with damage in neural motor units, in connective tissues, and the force generation mechanism. The objective of this study was to introduce a new method to quantify the real-time changes in skeletal muscle forces of rats during injurious stretch–shortening cycles. Male Sprague Dawley rats (n=24) were selected for use in this study. The dorsi flexor muscle group was exposed to either 150 stretch–shortening cycles (n=12) or 15 isometric contractions (n=12) in vivo using a dynamometer and electrical stimulation. Muscle damage after exposure to stretch–shortening cycles was verified by the non-recoverable force deficit at 48 h and the presence of myofiber necrosis. Variations of the dynamic forces during stretch–shortening cycles were analyzed by decomposing the dynamic force signature into peak force (F_peak), minimum force (F_min), average force (F_mean), and cyclic force (F_a). After the 15th set of stretch–shortening cycles, the decrease in the stretch–shortening parameters, F_peak, F_min, F_mean, and F_a, was 50% (P<0.0001), 26% (P=0.0055), 68% (P<0.0001), and 50% (P<0.0001), respectively. Our results showed that both isometric contractions and stretch–shortening cycles induce a reduction in the isometric force. However, the force reduction induced by isometric contractions fully recovered after a break of 48 h while that induced by stretch–shortening cycles did not. Histopathologic assessment of the tibialis anterior exposed to stretch–shortening cycles showed significant myofiber degeneration and necrosis with associated inflammation, while muscles exposed to isometric contractions showed no myofiber degeneration and necrosis, and limited inflammation. Our results suggest that muscle damage can be identified by the non-recoverable isometric force decrement and also by the variations in the dynamic force signature during stretch–shortening cycles.     

Effect of a Selenium-Deficient Diet on Blood Values of T3 and T4 in Cows

Pastures in the south of Chile have been shown to be selenium deficient, and as selenium is a component of deiodinase type 1, which is necessary for the synthesis of triiodothyronine (T3) at peripheral levels, the effect of selenium deficiency on the blood concentration of theses hormones in cows was studied. Twelve pregnant Friesian cows were randomly allocated into two homogeneous groups of six animals each - selenium supplemented and selenium deficient. The selenium deficient diet consisted of 11.5 kg of hay, 500 g of soya bran, 150 g of mineral mix (without selenium), 500 g of fat for animal feeding, and was given from day 15 of lactation until the end of the study. A commercial concentrate (Cosetan) and urea was also given according to lactation requirements (up to 5 kg and up to 120 g, respectively). The selenium content was 0.05 ppm of dry matter (equivalent to 18% of the daily requirements). The supplemented group was injected subcutaneously with 1 mg Se/kg, using the commercial product Deposel (1 ml/50kg). Blood samples were obtained by coccygeous vein venepuncture before supplementation (prepartum basal values) and thereafter every 15 days. GSH-Px activity in plasma was measured using a HITACHI 4020 spectrophotometer. Serum T3 and thyroxine (T4) concentrations were measured by electrochemiluminiscence. ANOVA, Tuckey test and Student’s t-test were used to establish the significance of the intra group differences, with p=<0.05 being considered significant. There were no significant differences in blood values of T4 in either the supplemented or non-supplemented groups during pregnancy and lactation. However the blood values of T4 decreased significantly (p=<0.05) during days 30–60 of lactation to values below the reference range. The T3 serum concentrations in the supplemented group of cows were significantly lower (p=<0.05) at 60, 90 and 150 days of lactation than cows that had been supplemented with selenium.     

Influence of upper body position on middle cerebral artery blood velocity during continuous positive airway pressure breathing

Continuous positive airway pressure (CPAP) is a treatment modality for pulmonary oxygenation difficulties. CPAP impairs venous return to the heart and, in turn, affects cerebral blood flow (CBF) and augments cerebral blood volume (CBV). We considered that during CPAP, elevation of the upper body would prevent a rise in CBV, while orthostasis would challenge CBF. To determine the body position least affecting indices of CBF and CBV, the middle cerebral artery mean blood velocity (MCA V _mean) and the near-infrared spectroscopy determined frontal cerebral hemoglobin content (cHbT) were evaluated in 11 healthy subjects during CPAP at different body positions (15° head-down tilt, supine, 15°, 30° and 45° upper body elevation). In the supine position, 10 cmH₂O of CPAP reduced MCA V _mean by 9 ± 3% and increased cHbT by 4 ± 2 μmol/L (mean ± SEM); (P < 0.05). In the head-down position, CPAP increased cHbT to 13 ± 2 μmol/L but left MCA V _mean unchanged. Upper body elevation by 15° attenuated the CPAP associated reduction in MCA V _mean (−7 ± 2%), while cHbT returned to baseline (1 ± 2 μmol/L). With larger elevation of the upper body MCA V _mean decreased progressively to −17 ± 3%, while cHbT remained unchanged from baseline. These results suggest that upper body elevation by ∼15° during 10 cmH₂O CPAP prevents an increase in cerebral blood volume with minimal effect on cerebral blood flow.     

Exercise-induced intravascular haemolysis in standardbred horses

 In human sports medicine a pathophysiological condition called `sports anaemia' is reported. This condition has been attributed to episodes of intravascular haemolysis induced by physical exercise. The occurrence of haemolytic episodes is indicated by the presence of high values of free plasma haemoglobin and lower plasma levels of haptoglobin after physical exercise. The literature regarding sports anaemia in horses, and in particular haemolysis induced by physical exercise, is rather limited. The purpose of this study was to evaluate the markers of intravascular haemolysis (plasma haemoglobin and haptoglobin) in Standardbred horses immediately after a race, in order to ascertain the presence of intravascular haemolysis, possibly induced by physical activity. We reported both the haptoglobin and free plasma haemoglobin values as a percentage of the total protein to avoid any influence of haemoconcentration induced by the exertion during the race. Free plasma haemoglobin concentration showed a significant increase both at 5 min (p < 0.01) and 10 min (p < 0.05) after exercise. A significant decrease in the haptoglobin occurred in both post-exercise blood samples, and was statistically significant 10 min after the race (p < 0.05). These data suggested that episodes of intravascular haemolysis may occur during physical activity in Standardbred horses. Received: 13 May 2002 / Accepted: 15 September 2002 Acknowledgements The authors are very grateful to Dr Lorenzo Berti (Florence, Italy) for his assistance in enrolling the subjects for the study; and to Dr David Marlin (Animal Health Trust, Newmarket, UK) for his advice.     

Longevity-associated NADH dehydrogenase subunit-2 237 Leu/Met polymorphism influences the effects of alcohol consumption on serum uric acid levels in nonobese Japanese men

NADH dehydrogenase subunit-2 237 leucine/methionine (ND2-237 Leu/Met) polymorphism is reportedly associated with longevity in the Japanese population. The ND2-237Met genotype may confer resistance to cardiovascular and cerebrovascular atherogenic diseases. Hyperuricemia is one of the risk factors for cardiovascular disease. To investigate whether ND2-237 Leu/Met polymorphism is associated with serum uric acid (SUA) levels, we conducted a cross-sectional study in 321 healthy Japanese male subjects. In nonobese (body mass index, BMI<25) male subjects, interaction between ND2-237 Leu/Met genotypes and drinking frequency on SUA levels was observed (P=0.031). The SUA levels were significantly higher in daily drinkers with ND2-237Leu than in non-daily drinkers with ND2-237Leu (P=0.018). In nonobese men, after adjustment for covariates, daily drinkers with ND2-237Leu had a significantly higher odds ratio (OR) for hyperuricemia (SUA≥6.5 mg/dl: vs. daily drinkers with ND2-237Met, OR=3.26, 95% confidence interval (CI) 1.14–9.29; vs. non-daily drinkers with ND2-237Leu, OR=3.22, 95% CI 1.39–7.45; SUA≥7.0 mg/dl: vs. non-daily drinkers with ND2-237Met, OR=3.53, 95% CI 1.00–12.4). However, in obese (BMI≥25) men, no significant interaction between ND2-237 Leu/Met polymorphism and habitual drinking on SUA levels or on the risk for hyperuricemia was observed. These results suggest that ND2-237 Leu/Met polymorphism modulates the effects of daily alcohol consumption on SUA levels in nonobese Japanese men.     

Distribution of Total,Free, Peptide-bound and Protein-bound Hydroxyproline in the Erythrocytes from Different Species

We have investigated the presence of total, free, protein-bound and peptide-bound hydroxyproline (Hyp) in the erythrocytes of different mammals namely, camel, bovine, sheep, human, rabbit and rat. Sheep erythrocytes had the highest concentration of free Hyp, followed by camel, bovine, rat, human and rabbit. The concentration of peptide-bound Hyp was the highest in camel erythrocytes followed by bovine, sheep (p<0.01), rat, human and rabbit (p<0.001). However, human erythrocytes had the highest concentration of protein-bound Hyp followed by rat, bovine, camel, rabbit and sheep (p<0.05). Camel erythrocytes had the highest concentration of total Hyp followed by bovine, sheep, rat (p<0.01), human and rabbit (p<0.001). Results showed that the ratio of free to peptide-bound Hyp was significantly higher in sheep as compared to other examined species (p<0.001). These variations in Hyp distribution may result from differences in collagen structure and/or composition in these species. Alternatively, they may be due to the fact that the circulating concentration of free Hyp is controlled by liver Hyp oxidase which regulates the concentration of free Hyp in plasma.     

Comparative Cell Shape and Diffusional Water Permeability of Red Blood Cells from Indian Elephant (Elephas maximus) and Man (Homo sapiens)

Red blood cells (RBC) from an Indian elephant (Elephas maximus) were studied by light microscopy (LM), scanning electron microscopy (SEM) and a new nuclear magnetic resonance (NMR) ‘imaging’ method based on the translational diffusion of water, NMR q-space analysis. Also, the transmembrane diffusional permeability, P _d of water in RBC was measured by using a Mn²⁺-doping NMR technique, taking human RBC as a reference. The main diameter of the elephant RBC was measured as 9.3 ± 0.7 μm by LM, 9.3 ± 0.7 μm by ‘shrinkage-corrected’ SEM, and 9.3 ± 0.4 μm by q-space anlaysis. The value is ∼1.4 μm larger than that for the human RBC. The values of P _d were, in the case of elephant RBC, 3.2 × 10⁻³ cm/s at 25 °C, 3.9 × 10⁻³ cm/s at 30 °C, 5.2 × 10⁻³ cm/s at 37 °C and 6.5 × 10⁻³ cm/s at 42 °C; all values were significantly lower than the corresponding values of P _d for human RBC, namely 4.3 × 10⁻³ cm/s at 25 °C, 5.2 × 10⁻³ cm/s at 30 °C, 6.1 × 10⁻³ cm/s at 37 °C, 7.8 × 10⁻³ cm/s at 42°C. The maximal inhibition of P _d (56%) was reached in 30 min at 37 °C with 2 mm p-chloromercuribenzene sulphonate (PCMBS) for both species of RBC. The basal permeability to water at 37 °C was estimated to be 2.3 × 10⁻³ cm/s for elephant and 2.6 × 10⁻³ cm/s for human RBC. The values of the activation energy for water permeability (E _a,d ) was significantly higher for elephant RBC (31.9 kJ/mol) than for human RBC (25.9 kJ/mol). This indicated that features other than the number of transporters per cell are likely to be important in defining the differences in water permeability in the RBC from the two species.     

Comparative Cell Shape and Diffusional Water Permeability of Red Blood Cells from Indian Elephant ( Elephas maximus ) and Man ( Homo sapiens )

Red blood cells (RBC) from an Indian elephant (Elephas maximus) were studied by light microscopy (LM), scanning electron microscopy (SEM) and a new nuclear magnetic resonance (NMR) ‘imaging’ method based on the translational diffusion of water, NMR q-space analysis. Also, the transmembrane diffusional permeability, P _d of water in RBC was measured by using a Mn²⁺-doping NMR technique, taking human RBC as a reference. The main diameter of the elephant RBC was measured as 9.3 ± 0.7 μm by LM, 9.3 ± 0.7 μm by ‘shrinkage-corrected’ SEM, and 9.3 ± 0.4 μm by q-space anlaysis. The value is ∼1.4 μm larger than that for the human RBC. The values of P _d were, in the case of elephant RBC, 3.2 × 10⁻³ cm/s at 25 °C, 3.9 × 10⁻³ cm/s at 30 °C, 5.2 × 10⁻³ cm/s at 37 °C and 6.5 × 10⁻³ cm/s at 42 °C; all values were significantly lower than the corresponding values of P _d for human RBC, namely 4.3 × 10⁻³ cm/s at 25 °C, 5.2 × 10⁻³ cm/s at 30 °C, 6.1 × 10⁻³ cm/s at 37 °C, 7.8 × 10⁻³ cm/s at 42°C. The maximal inhibition of P _d (56%) was reached in 30 min at 37 °C with 2 mm p-chloromercuribenzene sulphonate (PCMBS) for both species of RBC. The basal permeability to water at 37 °C was estimated to be 2.3 × 10⁻³ cm/s for elephant and 2.6 × 10⁻³ cm/s for human RBC. The values of the activation energy for water permeability (E _a,d ) was significantly higher for elephant RBC (31.9 kJ/mol) than for human RBC (25.9 kJ/mol). This indicated that features other than the number of transporters per cell are likely to be important in defining the differences in water permeability in the RBC from the two species.     

Na+-dependent regulation of the free Mg2+ concentration in neuropile glial cells and P neurones of the leech Hirudo medicinalis

 To investigate the Mg²⁺ regulation in neuropile glial (NG) cells and pressure (P) neurones of the leech Hirudo medicinalis the intracellular free Mg²⁺ ([Mg²⁺]_i) and Na⁺ ([Na⁺]_i) concentrations, as well as the membrane potential (E _m), were measured using Mg²⁺- and Na⁺-selective microelectrodes. The mean steady-state values of [Mg²⁺]_i were found to be 0.91 mM (mean E _m=–63.6 mV) in NG cells and 0.20 mM (mean E _m=–40.6 mV) in P neurones with a [Na⁺]_i of 6.92 mM (mean E _m=–61.6 mV) and 7.76 mM (mean E _m=–38.5 mV), respectively. When the extracellular Mg²⁺ concentration ([Mg²⁺]_o) was elevated, [Mg²⁺]_i in P neurones increased within 5–20 min whereas in NG cells a [Mg²⁺]_i increase occurred only after long-term exposure (6 h). After [Mg²⁺]_o was reduced back to 1 mM, a reduction of the extracellular Na⁺ concentration ([Na⁺]_o) decreased the inwardly directed Na⁺ gradient and reduced the rate of Mg²⁺ extrusion considerably in both NG cells and P neurones. In P neurones Mg²⁺ extrusion was reduced to 15.4% in Na⁺-free solutions and to 6.0% in the presence of 2 mM amiloride. Mg²⁺ extrusion from NG cells was reduced to 6.2% in Na⁺-free solutions. The results suggest that the major [Mg²⁺]_i-regulating mechanism in both cell types is Na⁺/ Mg²⁺ antiport. In P neurones a second, Na⁺-independent Mg²⁺ extrusion system may exist. Received: 11 August 1998 / Received after revision: 14 October 1998 / Accepted: 15 October 1998     

Serum Matrix Metalloproteinase-2 Levels Indicate Blood–CSF Barrier Damage in Patients with Infectious Meningitis

Objective Protein components in cerebrospinal fluid (CSF) are maintained at a specific concentration by a dynamic gradient between the capillary and intrathecal spaces via the blood–cerebrospinal fluid barrier (BCB) in the brain and spinal cord. Permeability to proteins increases when there is structural damage to the BCB. Matrix metalloproteinase-2 (MMP-2; gelatinase A) has been shown to degrade type IV collagen, a major component of the cellular basement membrane. We analyzed α2 macroglobulin (α2M) indices and evaluated the relationship between α2M, as an indicator of BCB permeability, and MMP-2, which degrades the extra-cellular matrix in patients with infectious meningitis. Materials and Methods Albumin levels in CSF or serum were determined by turbidimetric immunoassay, or bromcresol green assay, respectively. α2M levels in CSF or serum were measured with enzyme-linked immunosorbent assay, or laser-nephelometry, respectively. Serum MMP-2 levels were determined by enzyme immuno assay. We calculated the α2M index, i.e. the ratio of α2M (CSF / serum) to albumin (CSF / serum; α2M in CSF / α2M in serum × albumin in serum / albumin in CSF). Results α2M indices were significantly increased in infectious meningitis compared to healthy controls (p < 0.05). They were highest in bacterial meningitis, and there was a significant difference between viral or mycotic and bacterial meningitis (p < 0.05). Serum MMP-2 levels were increased in infectious meningitis, being highest in bacterial meningitis, where they were significantly different from healthy controls (p < 0.05). There was a significant positive correlation between serum MMP-2 levels and α2M indices (r = 0.64, p < 0.0001). Conclusion Markedly increased levels of serum MMP-2 in infectious, especially bacterial, meningitis may reflect the degree of damage to the BCB.     

Cation-osmotic haemolysis in stroke patients

Erythrocyte microrheology changes were measured by cation-osmotic haemolysis (COH) in healthy donors, patients with ischameic stroke, and patients who died within four days after a stroke. COH in patients with stroke was significantly decreased in comparison with that from healthy donors. In patients who died, COH was significantly decreased compared to patients who survived. The relationship between cationosmotic haemolysis and erythrocyte deformability is discussed.     

Cation-osmotic haemolysis in stroke patients

Erythrocyte microrheology changes were measured by cation-osmotic haemolysis (COH) in healthy donors, patients with ischameic stroke, and patients who died within four days after a stroke. COH in patients with stroke was significantly decreased in comparison with that from healthy donors. In patients who died, COH was significantly decreased compared to patients who survived. The relationship between cationosmotic haemolysis and erythrocyte deformability is discussed.     

Studies on the Relationship Between Haemoglobin Types of Adult Dromedary Camels and the Concentrations of Haemoglobin, Copper, Ceruloplasmin and Iron

The relationship between haemoglobin types of adult dromedary camels and the concentrations of haemoglobin, copper, ceruloplasmin and iron were studied. Blood samples were taken from the jugular vein of 100 clinically healthy Iranian dromedary camels according to their age (1–2, 2–4, 4–6 and >6 years) and sex. Haemoglobin electrophoresis showed two haemoglobin types: HbA (95.2%) and HbA₂ (4.8%). Age and sex had no significant effect on haemoglobin types nor on the concentrations of haemoglobin, copper, ceruloplasmin and iron. There was no correlation between the concentrations of haemoglobin, copper, iron, ceruloplasmin, HbA and HbA₂.     

Serum lipid profiles and their correlation with thyroid hormones in clinically healthy Turkoman horses

 Blood samples were collected from the jugular vein of 50 clinically healthy Turkoman horses according to their age (2–3, 3–5 and >5 years) and sex. Variations in the serum concentrations of cholesterol, triglyceride, total lipid, very low-density lipoprotein (VLDL cholesterol), low-density lipoprotein (LDL cholesterol) and high-density lipoprotein (HDL cholesterol), and their correlations with the concentrations of triiodothyronine (T₃) and thyroxine (T₄) were investigated. With an increase in the age of animals, there were significant increases (p=<0.05) in the cholesterol, triglyceride, total lipid, HDL cholesterol, LDL cholesterol and VLDL cholesterol concentrations. However, sex showed no significant differences on the concentrations of these parameters. The concentrations of T₃ and T₄ were significantly different in male and female Turkoman horses (p=<0.05). There were no significant correlations between thyroid hormones (T₃ and T₄) and serum lipids and cholesterol concentations in lipoproteins. Received: 11 June 2002 / Accepted: 6 November 2002     

Enhanced cerebral CO2 reactivity during strenuous exercise in man

Light and moderate exercise elevates the regional cerebral blood flow by ~20% as determined by ultrasound Doppler sonography (middle cerebral artery mean flow velocity; MCA V _mean). However, strenuous exercise, especially in the heat, appears to reduce MCA V _mean more than can be accounted for by the reduction in the arterial CO₂ tension (P _aCO₂). This study evaluated whether the apparently large reduction in MCA V _mean at the end of exhaustive exercise relates to an enhanced cerebrovascular CO₂ reactivity. The CO₂ reactivity was evaluated in six young healthy male subjects by the administration of CO₂ as well as by voluntary hypo- and hyperventilation at rest and during exercise with and without hyperthermia. At rest, P _aCO₂ was 5.1±0.2 kPa (mean ± SEM) and MCA V _mean 50.7±3.8 cm s⁻¹ and the relationship between MCA V _mean and P _aCO₂ was linear (double-log slope 1.1±0.1). However, the relationship became curvilinear during exercise (slope 1.8±0.1; P<0.01 vs. rest) and during exercise with hyperthermia (slope 2.3±0.3; P<0.05 vs. control exercise). Accordingly, the cerebral CO₂ reactivity increased from 30.5±2.7% kPa⁻¹ at rest to 61.4±10.1% kPa⁻¹ during exercise with hyperthermia (P<0.05). At exhaustion P _aCO₂ decreased 1.1±0.2 kPa during exercise with hyperthermia, which, with the determined cerebral CO₂ reactivity, accounted for the 28±10% decrease in MCA V _mean. The results suggest that during exercise changes in cerebral blood flow are dominated by the arterial carbon dioxide tension.     

Middle cerebral artery blood velocity,arterial diameter and muscle sympathetic nerve activity during post-exercise muscle ischaemia

During exercise the transcranial Doppler determined mean blood velocity (V_mean) increases in the middle cerebral artery (MCA) and reflects cerebral blood flow when the diameter at the site of investigation remains constant. Sympathetic activation could induce MCA vasoconstriction and in turn elevate V_mean at an unchanged cerebral blood flow. In 12 volunteers we evaluated whether V_mean relates to muscle sympathetic nerve activity (MSNA) in the peroneal nerve during rhythmic handgrip and post-exercise muscle ischaemia (PEMI). The luminal diameter of the dorsalis pedis artery (AD) was taken to reflect the MSNA influence on a peripheral artery. Rhythmic handgrip increased heart rate (HR) from 74 ± 20 to 92 ± 21 beats min^?1 and mean arterial pressure (MAP) from 87 ± 7 to 105 ± 9 mmHg (mean ± SD; P < 0.05). During PEMI, HR returned to pre-exercise levels while MAP remained elevated (101 ± 9 mmHg). During handgrip contralateral MCA V_mean increased from 65 ± 10 to 75 ± 13 cm s^?1 and this was more than on the ipsilateral side (from 63 ± 10 to 68 ± 10 cm s^?1; P < 0.05). On both sides of the brain V_mean returned to baseline during PEMI. MSNA did not increase significantly during handgrip (from 56 ± 24 to 116 ± 39 units) but the elevation became statistically significant during PEMI (135 ± 86 units, P < 0.05), while AD did not change. Taken together, during exercise and PEMI, V_mean changed independent of an elevation of MSNA by more than 140% and the dorsalis pedis artery diameter was stable. The results provide no evidence for a vasoconstrictive influence of sympathetic nerve activity on medium size arteries of the limbs and the brain during rhythmic handgrip and post-exercise muscle ischaemia.