Role of inflammation, oxidative stress, and autonomic nervous system activation during the development of right and left cardiac remodeling in experimental pulmonary arterial hypertension.

This study investigated the impact of experimental pulmonary arterial hypertension (PAH) progression by evaluating morphometric and functional parameters, oxidative stress, autonomic nervous system (ANS) activation, and inflammation in the right (RV) and left (LV) ventricles. Male rats were first divided into two groups: monocrotaline (MCT) and control. The MCT group received a single MCT injection (60 mg/kg, intraperitoneal), while control received saline. The MCT and control groups were further divided into four cohorts based on how long they were observed: 1, 2, 3, and 4 weeks. Animals were submitted to echocardiographic and hemodynamic analysis. RV and LV were used for morphometric, biochemical, and histological measurements. Autonomic modulation was evaluated by cardiac spectral analysis, considering two components: low frequency (LF) and high frequency (HF). Lung and liver weight was used for morphometric analysis. MCT induced 100% mortality at 4 weeks. In the RV, disease progression led to mild inflammation and enhanced reactive oxygen species (ROS) in week 1, followed by moderate inflammation, ROS production, and hypertrophy in week 2. By week 3, there was moderate inflammation, oxidative stress, and ANS imbalance, with development of right heart dysfunction. LV biochemical changes and inflammation were observed at week 3. The initial changes appeared to be related to inflammation and ROS, and the later ones to inflammation, oxidative stress, and ANS imbalance in MCT animals. This study reinforces the severity of the disease in the RV, the late effects in the LV, and the role of ANS imbalance in the development of heart dysfunction.

Worldwide distribution of common IDUA pathogenic variants.

Mucopolysaccharidosis type I (MPS I) is a rare disorder caused by deleterious sequence variants in the α-L-iduronidase (IDUA) gene. More than 200 pathogenic variants have been described so far, but their frequencies have not yet been analyzed on a worldwide scale. To address this, we analyzed the genotypes of MPS I patients from 35 published studies papers. The most common pathogenic variant observed was p.Trp402Ter. With frequencies of up to 63%, it was the major allele in most European countries, America and Australia. The variant p.Gln70Ter was also frequent; it was found mainly in Northern and Eastern Europe. The most frequent variant in North African countries was p.Pro533Arg; in Morocco, it represented more than 90% of mutant alleles. Variants observed in East Asians were not found in Western populations, including c.1190-1G>A, p.Ala79Val, p.Leu346Arg and c.613_617dupTGCTC. Conversely, p.Trp402Ter and p.Pro533Arg were not found in patients from East Asia. In conclusion, the most common pathogenic IDUA variant in MPS I patients are p.Trp402Ter, p.Gln70Ter and p.Pro533Arg. Knowledge about the genetic background of MPS I for each population is essential when developing new genotype-targeted therapies, as well as to enable faster genetic analysis and improve patient management.

Photostimulation of Japanese quail.

To adapt commercial poultry production to a new scenario of energy savings and to develop specific practices for quail production aimed at reducing costs while maintaining or improving productivity, four experiments were conducted. In the first experiment, birds were allocated to four treatments (photoperiod duration): T1: 14 L:10 D; T2: 15 L:9 D; T3: 16 L:8 D; and T4: 17 L:7 D. In the second experiment, birds were subjected to four levels of brightness: T1: 5 lux; T2: 10 lux; T3:15 lux; and T4: 22 lux (control). In the third experiment, four types of lamps were evaluated: T1: compact fluorescent lamp (color temperature: 6,500 K); T2: compact fluorescent lamp (color temperature: 2,700 K); T3: incandescent lamp; and T4: yellow LED. In the last experiment, four lighting programs were compared: T1: continuous program (control), in which there was a single photoperiod of 15 h; the other treatments consisted of intermittent lighting programs, as follows: T2: 1 h of light provided 1 h after dusk; T3: 1 h of light provided 2 h before dawn; T4: half an hour of light provided 1 h after dusk and half an hour of light provided 1.5 h before dawn. In each experiment, 1,296 Japanese quail were evaluated for four 28-d cycles, totaling 112 experimental days. A completely randomized experimental design of 4 treatments with 12 replicates of 27 birds each was applied in all trials. Performance and egg quality were evaluated in each experiment. Higher egg production and adequate egg quality, as well as energy savings, can be obtained with Japanese quail using compact fluorescent lamps or LEDs and a photoperiod of 15 h/d supplied using an intermittent lighting program, with 1 h of artificial light 2 h before dawn at a brightness of 5 lux.

Apolipoprotein A-I and cholesterol in synovial fluid of patients with rheumatoid arthritis, psoriatic arthritis and osteoarthritis.

OBJECTIVE: To investigate lipid and apolipoprotein (Apo) levels in synovial fluid (SF) and serum of patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and osteoarthritis (OA). METHODS: SF of 44 patients (14 RA, 14 PsA, 16 OA) was tested for Apo A-I, HDL-C, total cholesterol (TC), IL-1Beta, TNF-alpha, white blood cell count (WBC) and polymorphonucleate (PMN) percentage. Blood samples, collected simultaneously to the SF, were examined for Apo A-I, HDL-C, TC, TNF-alpha, serum amyloid A (SAA) and C-reactive protein (CRP). Thirty-three healthy donors served as a control group. RESULTS: Serum levels of Apo A-I, HDL-C and TC were higher in OA as compared with RA, PsA and the control group. The patients with inflammatory arthritis had lower serum levels of Apo A-I and HDL-C than did the controls. Apo A-I concentrations were higher in SF of RA patients, while PsA showed the highest concentration of TC, though not reaching statistical significance. A negative correlation was found between serum Apo A-I and synovial WBC (r=-0.48 p=0.002) and IL-1Beta (r=-0.42 p=0.016). There was a strong positive correlation between the Apo A-I SF/serum ratio and synovial WBC (r=0.73 p<0.001), IL-1Beta (r=0.68 p<0.001) and a weak, yet significant, correlation with serum CRP (r=0.49 p=0.002) and SAA (r=0.41 p=0.008). CONCLUSION: Our study confirms that in RA Apo A-I and TC levels are decreased in plasma and increased in SF, thus suggesting infiltration of HDL particles in the inflamed joint with inhibition of the local production of proinflammatory cytokines. On the other hand, it can be hypothesized that the sequestration of Apo A-I in the inflamed tissue may, in part, account for the reduction of circulating HDL and the excess cardiovascular risk in RA and PsA patients.

Upper limb bone mineral density and body composition measured by peripheral quantitative computed tomography in right-handed adults: the role of the dominance effect.

BACKGROUND: To investigate the impact on bone and muscle of pathological conditions involving only one of the upper limbs, it is important to know the physiological differences due to the dominance effect. AIM: To evaluate any physiological differences between dominant and non-dominant upper limbs in terms of bone mineral density (BMD), muscle mass, and muscle density at different levels. SUBJECTS AND METHODS: The study considered 60 right-handed healthy adults, 30 men and 30 women. Cortical BMD, muscle area, and muscle density were investigated by pQCT-XCT-3000 Stratec at the proximal radius, trabecular and total BMD at the distal radius, and trabecular and cortical BMD at the second phalanx of the third finger. Hand grip strength was also measured. RESULTS: No significant differences in BMD were found between the dominant and non-dominant upper limbs at any of the sites considered, in men or women. Muscle density was also similar on the two sides, whereas muscle area at the proximal radius was significantly lower on the non-dominant side in both men [4177.5+/-475.1 vs 4009.3+/-552.7 mm2; Delta%: 4.1%; 95% confidence interval (CI) 1.7%-6.5%] and women (2903.9+/-470.9 vs 2720.3+/-411.7 mm2; Delta%: 6.1%; 95%CI 4.3%-7.9%). Hand grip strength proved greater on the right side in both men (48.5+/-8.8 vs 45.2+/-8.7 kg; Delta% 7.1; p<0.001) and women (29.1+/-4.3 vs 27.0+/-5.1 kg; Delta% 7.1; p<0.001). CONCLUSION: The dominance effect does not seem to influence trabecular or cortical BMD at any of the sites in the upper limb. Muscle density is not modified by dominance, while muscle area is reduced on the non-dominant side and this should be borne in mind when the effect of pathological conditions on the body composition of a single forearm is investigated.

Characterization with zonal ultracentrifugation of low-density lipoproteins in type V hyperlipoproteinemia.

Low-density lipoproteins (density = 1.019-1.063 g/ml) were isolated in 10 subjects with type V hyperlipoproteinemia by ultracentrifugation in a zonal rotor under rate flotation conditions. Plasma LDL concentrations in these patients were extremely reduced, as well as being heterogeneous, and two different subclasses consisting of LDL2 (density = 1.019-1.045 g/ml) and LDL3 (density = 1.045-1.063 g/ml) were observed. LDL2 and LDL3 have similar electrophoretic mobilities in beta position in agarose gel, and their diameters, calculated from gel filtration studies, were inversely proportional to their densities. LDL2 and LDL3 have a mean hydrated density of 1.034 and 1.054 g/ml, respectively. In comparison with normal LDL2, the LDL2 and LDL3 of hypertriglyceridemic subjects are particularly rich in triacylglycerols and poor in cholesteryl esters and free cholesterol, while they have an increasing amount of proteins. The protein moiety is composed almost exclusively of apolipoprotein B-100 in IDL, LDL2 and LDL3 ; in addition, IDL also contain apolipoprotein C peptides. This characterization of LDL heterogeneity in type V hyperlipoproteinemia should be considered in interpreting kinetic data in human normal and pathological lipid metabolism and in evaluating the atherogenic risk of hypertriglyceridemia.

Two functionally different Na/K pumps in cardiac ventricular myocytes.

The whole-cell patch-clamp technique was used to voltage clamp acutely isolated myocytes at -60 mV and study effects of ionic environment on Na/K pump activity. In quiescent guinea pig myocytes, normal intracellular Na+ is approximately 6 mM, which gives a total pump current of 0.25 +/- 0.09 pA/pF, and an inward background sodium current of 0.75 +/- 0.26 pA/pF. The average capacitance of a cell is 189 +/- 61 pF. Our main conclusion is the total Na/K pump current comprises currents from two different types of pumps, whose functional responses to the extracellular environment are different. Pump current was reversibly blocked with two affinities by extracellular dihydro-ouabain (DHO). We determined dissociation constants of 72 microM for low affinity (type-1) pumps and 0.75 microM for high affinity (type-h) pumps. These dissociation constants did not detectably change with two intracellular Na+ concentrations, one saturating and one near half-saturating, and with two extracellular K+ concentrations of 4.6 and 1.0 mM. Ion effects on type-h pumps were therefore measured using 5 microM DHO and on total pump current using 1 mM DHO. Extracellular K+ half-maximally activated the type-h pumps at 0.4 mM and the type-1 at 3.7 mM. Extracellular H+ blocked the type-1 pumps with half-maximal blockade at a pH of 7.71 whereas the type-h pumps were insensitive to extracellular pH. Both types of pumps responded similarly to changes in intracellular-Na+, with 9.6 mM causing half-maximal activation. Neither changes in intracellular pH between 6.0 and 7.2, nor concentrations of intracellular K+ of 140 mM or below, had any effect on either type of pump. The lack of any effect of intracellular K+ suggests the dissociation constants are in the molar range so this step in the pump cycle is not rate limiting under normal physiological conditions. Changes in intracellular-Na+ did not affect the half-maximal activation by extracellular K+, and vice versa. We found DHO-blockade of Na/K pump current in canine ventricular myocytes also occurred with two affinities, which are very similar to those from guinea pig myocytes or rat ventricular myocytes. In contrast, isolated canine Purkinje myocytes have predominantly the type-h pumps, insofar as DHO-blockade and extracellular K+ activation are much closer to our type-h results than type-1. These observations suggest for mammalian ventricular myocytes: (a) the presence of two types of Na/K pumps may be a general property. (b) Normal physiological variations in extracellular pH and K+ are important determinants of Na/K pump current. (c) Normal physiological variations in the intracellular environment affect Na/K pump current primarily via the Na+ concentration. Lastly, Na/K pump current appears to be specifically tailored for a tissue by expression of a mix of functionally different types of pumps.

Gap junctional coupling in lenses from alpha(8) connexin knockout mice.

Lens fiber cell gap junctions contain alpha(3) (Cx46) and alpha(8) (Cx50) connexins. To examine the roles of the two different connexins in lens physiology, we have genetically engineered mice lacking either alpha(3) or alpha(8) connexin. Intracellular impedance studies of these lenses were used to measure junctional conductance and its sensitivity to intracellular pH. In Gong et al. 1998, we described results from alpha(3) connexin knockout lenses. Here, we present original data from alpha(8) connexin knockout lenses and a comparison with the previous results. The lens has two functionally distinct domains of fiber cell coupling. In wild-type mouse lenses, the outer shell of differentiating fibers (see 1, DF) has an average coupling conductance per area of cell-cell contact of approximately 1 S/cm(2), which falls to near zero when the cytoplasm is acidified. In the inner core of mature fibers (see 1, MF), the average coupling conductance is approximately 0.4 S/cm(2), and is insensitive to acidification of the cytoplasm. Both connexin isoforms appear to contribute about equally in the DF since the coupling conductance for either heterozygous knockout (+/-) was approximately 70% of normal and 30-40% of the normal for both -/- lenses. However, their contribution to the MF was different. About 50% of the normal coupling conductance was found in the MF of alpha(3) +/- lenses. In contrast, the coupling of MF in the alpha(8) +/- lenses was the same as normal. Moreover, no coupling was detected in the MF of alpha(3) -/- lenses. Together, these results suggest that alpha(3) connexin alone is responsible for coupling MF. The pH- sensitive gating of DF junctions was about the same in wild-type and alpha(3) connexin -/- lenses. However, in alpha(8) -/- lenses, the pure alpha(3) connexin junctions did not gate closed in the response to acidification. Since alpha(3) connexin contributes about half the coupling conductance in DF of wild-type lenses, and that conductance goes to zero when the cytoplasmic pH drops, it appears alpha(8) connexin regulates the gating of alpha(3) connexin. Both connexins are clearly important to lens physiology as lenses null for either connexin lose transparency. Gap junctions in the MF survive for the lifetime of the organism without protein turnover. It appears that alpha(3) connexin provides the long-term communication in MF. Gap junctions in DF may be physiologically regulated since they are capable of gating when the cytoplasm is acidified. It appears alpha(8) connexin is required for gating in DF.

The cDNA sequence encoding the major intrinsic protein of frog lens.

A cDNA clone encoding the frog lens major intrinsic protein (MIP) has been isolated and sequenced. The predicted protein of 28 kDa has high sequence identity and similarity to mammalian and avian lens MIP sequences. Frog lens MIP is encoded by a transcript of 4.4 kb.

Relationship between triglyceride-rich lipoprotein (chylomicrons and VLDL) and HDL2 and HDL3 in the post-prandial phase in humans.

In order to evaluate the relationship between triglyceride-rich lipoproteins (chylomicrons and VLDL) and HDL during alimentary lipaemia, 12 healthy volunteers, 6 male and 6 female (aged 20--40 yrs), were studied. Cholesterol, phospholipid, triglyceride and protein were evaluated in whole serum, VLDL, LDL and HDL (successively subfractionated in HDL2 and HDL3). Blood samples were collected in a fasting state, 4.5 and 9 h after a 1500 calorie meal (20% protein, 40% carbohydrate, 40% fat). A striking increase in triglyceride-rich lipoproteins after 4.5 h was observed in both sexes, but was more pronounced in males. An increase in phospholipid and triglyceride as well as a slight reduction in cholesterol was evident in HDL after 4.5 h. At the same time both lipids and proteins were decreased in HDL3 and increased in HDL2. This phenomenon is more evident in females, who showed a significantly higher basal HDL2 level. These results suggest a possible metabolic relationship in the post-prandial phase between triglyceride-rich lipoproteins and HDL, and an inverse correlation between HDL2 and HDL3.

Long-term trial with colestipol plus clofibrate in familial hypercholesterolemia.

Twenty subjects with familial hypercholesterolemia (12 Type IIa and 8 Type IIb), previously treated with Colestipol for 16 months, were subjected to therapy with Colestipol (15 g/day) + clofibrate (2 g/day) for 15 months. During the second treatment period these patients continued to follow the isocaloric hypocholesterolemic diet initiated during the original trial. In Type IIa patients, the association of these drugs enhanced the decrease in plasma cholesterol levels. The total mean decrease was -40 +/- 17 mg/dl (P less than 0.05). In Type IIb patients, on the other hand, the association of clofibrate with Colestipol induced an increase in plasma cholesterol levels. The total mean increase was +24 +/- 7 mg/dl (P less than 0.05). A markedly significant decrease in plasma triglyceride levels was observed in this group (- 107 +/- 30; P less than 0.01). These results seem to indicate that, in Type IIa, clofibrate increased the resin's hypocholesterolemic effect. In Type IIb, on the other hand, the association of these drugs did not seem to be indicated since a marked hypotriglyceridemic effect was accompanied by an increase in plasma cholesterol levels. These results are briefly discussed in the light of recent data obtained on the effects of Colestipol and clofibrate on lipoprotein metabolism.

Familial lipoprotein lipase and apolipoprotein C-II deficiency. Lipoprotein and apoprotein analysis, adipose tissue and hepatic lipoprotein lipase levels in seven patients and their first degree relatives.

Plasma lipids, lipoproteins, tissue lipoprotein lipase (LPL) and hepatic lipase (H-TGL) were studied in 7 patients with familial hyperchylomicronemia from four different families. Their first-degree relative were also studied. The patients were heterogeneous for the genetic defect; LPL activity was absent in five patients (LPL deficiency) but normal in two. However, these two did not have apo C-II, the physiological activator of LPL (C-II deficiency). There were no significant differences in the clinical picture between patients with LPL deficiency and C-II deficiency. In both mutants, marked hypertriglyceridemia was due to an accumulation of lipoproteins of density less than 1.006 g/ml. The LDL fraction was very reduced and abnormal in composition, presenting a CH/TG ratio of 0.5. The plasma apolipoprotein B (apo B) level was low (67 +/- 5.5 mg/dl) and was transported mainly in the VLDL fraction (26 +/- 3.2 mg/dl) rather than in the LDL fraction (15 +/- 1.4 mg/dl). Very low levels of cholesterol and apolipoprotein A-I in HDL subfractions HDL2 and HDL3 were also recorded. Only 3 out of the 24 first-degree relatives of patients with LPL deficiency showed even a small increase in plasma triglycerides, but 15 had low or low to normal LPL values. H-TGL levels were normal in all subjects. The 4 first-degree relatives of C-II deficiency patients showed normal levels of plasma lipids. LPL and H-TGL, and 2 children of 1 patient showed normal distribution of apo C peptides in their VLDL. A block in chylomicron catabolism, due to the absence of LPL or apo C-II, may lead to a massive accumulation of lipoproteins with a density less than 1.006 g/ml, and a drastic reduction in the LDL and HDL fractions. Low LPL values in the first-degree relatives of LPL deficiency patients might represent a biochemical marker for healthy carriers of LPL deficiency.

Altered surfactant synthesis and function in rats with diet-induced hyperlipidemia.

Altered lung function in hyperlipidemic patients has been reported by many authors. An alteration of surfactant synthesis has been suggested. Isolated lungs of rats rendered hyperlipidemic by suitable diets display an increased distensibility at maximal inflation and a higher degree of alveolar stability during deflation. These alterations are related to modifications of surfactant properties. Lung lavage fluid obtained from hyperlipidemic rats displays an increase in percent content of phosphatidylglycerol and a decrease of phosphatidylethanolamine. The percent content of phosphatidylglycerol correlates with the circulating levels if free fatty acids (FFA). It is suggested that FFA might affect the activity of enzymes operating in lung phospholipid synthesis. The reported increase of surfactant phosphatidylglycerol might explain the increment of alveolar stability observed in hyperlipidemic rats.

Characterization of hyperlipidemia in two patients with analbuminemia.

The results of plasma lipid and lipoprotein analysis in two related patients, brother (R.U.) and sister (R.R.) with analbuminemia, and three first-degree relatives (parents and sister) are reported. Both patients showed a remarkable increase in cholesterol and phospholipid levels, and there was a corresponding increase in serum apo B and apo A-I. This hyperlipidemia is due to a selective increase in LDL and HDL concentrations. R.U. showed an increase in both HDL2- and HDL3-cholesterol, R.R. only in HDL3-cholesterol. VLDL concentration was reduced in R.U. and normal in R.R. The plasma lipoprotein electrophoretic pattern did not correspond to any of the phenotypes in Fredrickson's classification. Composition of the different lipoprotein fractions was normal in the patients and family members. Serum FFA level in R.R. was very low. An increase in the plasma protein fractions, particularly the transport fractions, was confirmed in both patients. The possible pathophysiology of the hypercholesterolemia in these patients is discussed. Unlike other reported cases, clinical signs of atherosclerotic complications were absent.

A comparative study of serum and synovial fluid lipoprotein levels in patients with various arthritides.

UNLABELLED: The aim of this study was to investigate apolipoprotein (apo) A-I, apo B, lipoprotein (Lp) (a), HDL-cholesterol (C), LDL-C, triglycerides (TG) and total cholesterol (TC) values in the serum and synovial fluid (SF) of untreated rheumatoid arthritis (RA), psoriatic arthritis (PsA), and osteoarthritis (OA) patients. METHODS: Paired SF and serum samples were collected simultaneously from 14 patients with RA, 14 with PsA, and 16 with OA and tested for apo A-I, apo B, HDL-C, LDL-C, Lp(a), TC and TG. Serum C reactive protein (CRP) and amyloid A (SAA) levels were also determined. RESULTS: The inflammatory arthritis patients had higher SF lipid levels with the exception of HDL. Reflecting increased synovial permeability, the lipid SF/serum ratio was always higher in RA and PsA with respect to OA patients. The positive correlation between serum and SF apo A-I, apo B, HDL-C, TG, and Lp(a) levels confirmed that there is lipoprotein diffusion into the SF. RA and PsA patients had lower concentrations of all serum lipids except for Lp(a) with respect to OA patients. The levels in the RA patients were similar to those in healthy matched controls, while the PsA patients had significantly lower apo A-I and HDL levels and higher apo B and LDL values. CONCLUSIONS: Lipid diffusion into the joint cavity, which largely depends on the degree of inflammation, may contribute to modulating local inflammatory processes.

Transient high-level expression of beta-galactosidase after transfection of fibroblasts from GM1 gangliosidosis patients with plasmid DNA.

GM1 gangliosidosis is an autosomal recessive disorder caused by the deficiency of lysosomal acid hydrolase beta-galactosidase (beta-Gal). It is one of the most frequent lysosomal storage disorders in Brazil, with an estimated frequency of 1:17,000. The enzyme is secreted and can be captured by deficient cells and targeted to the lysosomes. There is no effective treatment for GM1 gangliosidosis. To determine the efficiency of an expression vector for correcting the genetic defect of GM1 gangliosidosis, we tested transfer of the beta-Gal gene (Glb1) to fibroblasts in culture using liposomes. Beta-Gal cDNA was cloned into the expression vectors pSCTOP and pREP9. Transfection was performed using 4 microL lipofectamine 2000 and 1.5-2.0 microg DNA. Cells (2 x 10(5)/well) were harvested 24 h, 48 h, and 7 days after transfection. Enzyme specific activity was measured in cell lysate and supernatant by fluorometric assay. Twenty-four hours after transfection, treated cells showed a higher enzyme specific activity (pREP9-beta-Gal: 621.5 +/- 323.0, pSCTOP-beta-Gal: 714.5 +/- 349.5, pREP9-beta-Gal + pSCTOP-beta-Gal: 1859.0 +/- 182.4, and pREP9-ss-Gal + pTRACER: 979.5 +/- 254.9 nmol x h-1 x mg-1 protein) compared to untreated cells (18.0 +/- 3.1 for cell and 32.2 +/- 22.2 nmol x h-1 x mg-1 protein for supernatant). However, cells maintained in culture for 7 days showed values similar to those of untreated patients. In the present study, we were able to transfect primary patients' skin fibroblasts in culture using a non-viral vector which overexpresses the beta-Gal gene for 24 h. This is the first attempt to correct fibroblasts from patients with GM1 gangliosidosis by gene therapy using a non-viral vector.

Spatial variations in membrane properties in the intact rat lens.

We have used linear frequency domain techniques to measure impedance at various locations and depths in the intact rat lens. The data are used to obtain best-fit solutions to a new electrical model based on lens structure, allowing us to estimate localized conductances of surface cell membranes (Gs), fiber cell membranes (gm), and gap junctions (Gj) as functions of position. We find that gm is small and fairly uniform throughout the lens (2.02 +/- 0.58 microS/cm2); for the anterior surface-epithelial cells Gs = 1.26 +/- 0.19 mS/cm2; for the posterior surface differentiating fiber cells Gs = 0.46 +/- 0.04 mS/cm2. Thus, Gs varies about the equator in a stepwise fashion. Gj between fiber cells at locations interior to 80% of the radius is fairly uniform (0.75 S/cm2); but in the outer 20% Gj varies smoothly and symmetrically from both poles (0.66 S/cm2) to equator (5.95 S/cm2). This pattern of variation in Gj is similar to the pattern of inward and outward currents reported by Robinson and Patterson (1983. Curr. Eye Res. 2:843-847). We therefore suggest that the nonuniform distribution of functional gap junctions, not the surface cell conductance or Na/K pumps, may be responsible for directing these current flows. Gap junctional uncoupling during exposure to elevated calcium and acidification was also examined. High calcium (20 mM, with the calcium ionophore A23187) produced modest (twofold) irreversible uncoupling along with large, irreversible decreases in membrane potential. We did not pursue this further. Acidification with 20 and 100% CO2-bubbled Tyrode's produced 5- and 15-fold reversible uncoupling, respectively, only in the outer 20% of the lens radius. The remaining inner 80% of the lens gap junctions seemed resistant to the acidification and did not uncouple.

Alcohol induced burr cell (echinocytic) haemolytic anaemia and haemochromatosis.

A 51-year-old man with chronic alcoholic liver disease developed a severe haemolytic anaemia characterized by the presence of circulating burr-shaped cells (echinocytes). Several transfusions of packed red cells were ineffective in raising the haemoglobin concentration, showing that the abnormality was acquired by the transfused cells. Liver biopsies revealed haemochromatosis. Haematological parameters normalized four months after the patient stopped drinking alcohol, but burr cells were still present and erythrocyte life-span was still markedly shortened at one year follow-up. Since serum cholesterol, HDL-cholesterol, and Apo-AI and Apo-B lipoproteins were considerably decreased, the lipid composition of the red cell membrane was studied. Findings showed that echinocytosis occurred with no change in membrane cholesterol content, nor in cholesterol:phospholipid ratio, but with an alteration in the phosphatidylserine and phosphatidylinositol concentrations. While haemochromatosis was most likely the cause of the erythrocyte anomaly, alcohol intake was probably responsible for the acute onset of haemolytic anaemia with effects directly on the erythrocyte membrane as well as mediated by the progressive hepatic injury, with alterations in the plasma and successively in the intramembrane lipid composition.

Transient elevation of spontaneous release at the frog neuromuscular junction following acetylcholine iontophoresis.

Miniature end-plate currents (m.e.p.c.s) were recorded from frog neuromuscular junctions using a two-electrode voltage clamp. The m.e.p.c. frequency was temporarily elevated following 10s iontophoretic applications of acetylcholine (ACh) when the junctions were clamped at 100 mV. This post-ACh "burst" of quanta was also observed at unclamped junctions. At-100 mV, the intensity of the burst was proportional to the amount of current flowing across the end-plate during ACh iontophoresis, but usually did not reach its peak until the end-plate receptor channels were almost completely closed. Addition of 0.5 microM TTX to the Ringer's solution, or total replacement of sodium with guanidine, lithium, or methylamine did not inhibit the burst. No burst was observed in Ca2+-free, EGTA solutions, or in Ca2+-free solutions containing 2 mM Mn2+. Sr2+ effectively substituted for Ca2+. Addition of 2 mM Co2+ or Mn2+ to normal Ringer's did not inhibit the burst. Presynaptic muscarinic receptors did not obviously contribute to the burst, since it was not blocked by atropine, nor produced by oxotremorine or pilocarpine. The ACh analogs carbachol and acetyl-beta-methylcholine also produced the burst. The burst was highly dependent on the muscle membrane potential during the period of ACh iontophoresis, becoming more intense at potentials negative to -100 mV and disappearing at -60 mV. The critical importance of the post-synaptic membrane potential suggests that the burst may be due to an action of the muscle end-plate on the motor nerve terminal, possibly by the movement of an anionic substance through open end-plate receptor channels, but this hypothesis does not account for the delay of the burst until near the end of the ACh-induced end-plate current.

Physiological properties of the normal lens.

The lens is an avascular organ suspended between the aqueous and vitreous humors of the eye. The cellular structure is symmetric about an axis passing through its anterior and posterior poles but asymmetric about a plane passing through its equator. Because of its asymmetric structure, the lens has historically been assumed to perform transport between the aqueous and vitreous humors. Indeed, when anterior and posterior surfaces were isolated in an Ussing chamber, a translens current was measured. However, in the eye, the two surfaces are not isolated. The vibrating probe technique showed the current densities at the surface of a free-standing lens were surprisingly large, about an order of magnitude greater than measured in an Ussing chamber, and were not directed across the lens. Rather, they were inward in the region of either anterior or posterior pole and outward at the equator. This circulating current is the most dramatic physiological property of a normal lens. We believe it is essential to maintain clarity; hence, this review focuses on factors likely to drive and direct it. We review properties and spatial distribution of lens Na+/K+ pumps, ion channels, and gap junctions. Based on these data, we propose a model in which the difference in electromotive potential of surface versus interior cell membranes drives the current, whereas the distribution of gap junctions directs the current in the observed pattern. Although this model is clearly too simple, it appears to quantitatively predict observed currents. However, the model also predicts fluid will move in the same pattern as ionic current. We therefore speculate that the physiological role of the current is to create an internal circulatory system for the avascular lens.