The effect of fasting and protein calorie malnutrition on the liver porphyrins

• 1.1. Fractionation of the porphyrins extracted from the livers of fasting pigs shows a coproporphyrin to protoporphyrin ratio greater than unity, whereas the livers from normally fed pigs give a ratio less than unity.
• 2.2. Similar results are obtained when the liver porphyrins from guinea-pigs fed on protein deficient diet are compared with those from normally fed animals.
• 3.3. It is suggested that fasting causes a decrease in the ability of the liver to convert coproporphyrin to protoporphyrin, that is, inhibition of the enzyme coproporphyrinogen oxidase.

     

Kinetics of porphyrin accumulation in cultured epithelial cells exposed to ALA

• 1.1. The kinetics of porphyrin accumulation in cultured mammalian epithelial cells (CNCM-I-221) during exposure to ALA was investigated.
• 2.2. The total porphyrin synthesized is a function of ALA concentration and the incubation time. The cellular porphyrin content exhibited a saturation pattern, reaching a plateau at about 0.04 fmol porphyrins/cell. A biphasic time-dependent increase in the total porphyrin synthesized was observed.
• 3.3. After 3 hr of exposure to ALA the rate of synthesis increased to ahnost twice the initial rate, reaching between 0.02 and 0.05 fmol porphyrins/cell/hr depending on serum concentration in the medium.
• 4.4. Two effects of FBS on ALA-stimulated porphyrin accumulation were observed. Greater total porphyrin synthesis was found when incubations were made in 10% FBS compared to those in 1% FBS.
• 5.5. The higher serum concentration also caused a greater release into the medium of the porphyrins generated in the cells with a calculated half-life of 24 min in 10% serum-supplemented medium compared with 62 min in 1% serum.
• 6.6. The results obtained from cell synchronization experiments suggest that there is little obvious cell cycle-dependent variation in the synthesis of porphyrins from ALA.
• 7.7. The small differences in the intracellular porphyrin content that were observed may be attributed to a slight reduction in the rate of loss of porphyrins in G2/M cells.

     

The influence of chloroquine on the formation of porphyrins by yeasts

A single two-compartment model suitable for studying the production and elimination of porphyrins from cells was prepared. Chloroquine with increasing concentrations:-

• 1.1. Inhibits the total production of porphyrins.
• 2.2. Reduces intracellular concentration of porphyrins.
• 3.3. Increases transversal permeation of porphyrins through the cellular membrane.

     

Activation of neutrophils NADPH oxidase by PMA: Cytosol activity is translocated in phorbol-primed neutrophils

• 1.1. Translocation of cytosol activity in phorbol-primed neutrophils was studied.
• 2.2. Prior exposure of PMA or FMLP could potentiate the oxidative response by subsequent heterogeneous stimulus, FMLP or PMA.
• 3.3. In FMLP-primed neutrophils, the cytosol had almost the same activity as resting one and cytosol activity was not eluted from the membrane.
• 4.4. In PMA-primed neutrophils, however, the cytosol had less activity and cytosol activity was correspondingly eluted from the membrane.
• 5.5. These observations suggested that cytosol activity was translocated in PMA-primed cells.

     

Proteolytic cleavage of band 3 protein in relation to anion transport in fish (Oncorhynchus mykiss) red blood cells

• 1.1. The effects of trypsin and chymotrypsin on HCO₃⁻/Cl⁻ exchange through red blood cell membranes of humans and trout were studied.
• 2.2. To measure the anion exchange we used a right-angle light-scattering technique by applying the Jacobs-Stewart cycle in ammonium solution and the osmotiration method at constant cell volume.
• 3.3. The Cl⁻ flux in human red blood cells remained unaltered after treatment with external trypsin and chymotrypsin while in trout red blood cells the flux decreased.
• 4.4. This partial inhibition of anion transport in fish, ranging from 30 to 40%,suggest that one or several of the cleavage sites in band 3 protein, essential for anion transport function, are exposed in fish red blood cells.
• 5.5. In human red blood cells the fragments of band 3 which are affected by proteolytic digestion, retain their tertiary structure because there is no influence on anion transport.

     

The effect of temperature on oxygen equilibrium curves of trout blood (Salmo gairdnerii)

• 1.1. Oxygen equilibrium curves were measured on trout red blood cell suspensions at pH 7.8 and 8.4 at 15, 20 and 25 C. Normal red cells and red cells that had been depleted of their ATP content were used.
• 2.2. The equilibrium data were fitted to the Adair's model and the enthalpy (ΔH) and entropy (ΔS) changes for the first and fourth steps of oxygenation and for overall oxygenation were calculated from the temperature dependencies of the Adair constants.
• 3.3. For normal red blood cells, the apparent heat for the first oxygenation step, δh₁, is close to zero.
• 4.4. Temperature insensitivity of this step at physiological pH, combined with a large pH dependence, probably denotes a property of Hb4, the Root effect Hb of trout blood.
• 5.5. At pH 7.8, ΔH₄ is about —4kcal/mol, a small value which may be attributed to the large release of Bohr protons that occurs at the last oxygenation step and corresponds to an endothermic process which opposes to the exothermic oxygenation of the haem.
• 6.6. The ΔH₄ value appears to have a large influence on the enthalpy for overall oxygenation.
• 7.7. Results for ATP-free red cells are consistent with a mere increase in the intracellular pH and suggest that ATP has no specific effect at and above pH_i ~ 7.7.
• 8.8. Effects of temperature and pH on trout red blood cell isotherms emphasize the primary importance of the major component of trout blood, namely Hb4, in trout blood functional properties.

     

Acute hepatic porphyria syndrome with porphobilinogen synthase defect

On the basis of metabolite and enzyme studies a new type of acute hepatic porphyria with porphobilinogen synthase defect and repeated intermittent acute manifestations, abdominal colics, tachycardia and hypertension, and a persistent neurological syndrome was found in two young male patients. The main characteristic features are the following:

• 1.1. High urinary δ-aminolevulinic acid excretion( ⪢ 1 mmol/24hr), slight increase of porphobilinogen (up to 25 μmol/24 hr) and high increase of porphyrins (up to 22 μmol/24 hr) with coproporphyrin dominance.
• 2.2. Normal fecal and liver porphyrins.
• 3.3. Slight increase of erythrocyte protoporphyrin.
• 4.4. Decrease of porphobilinogen synthase activity in erythrocytes in both cases below 1% of healthy and not lead-exposed persons; normal activities of uroporphyrinogen synthase and decarboxylase in erythrocytes.
• 5.5. Low-normal lead concentrations in blood and low-normal lead excretion in urine in both cases; normal lead content in bone.
• 6.6. Normal plasma and urinary amino acids.
• 7.7. Irrelevant hepatological (liver biopsy), general clinical chemical and hematological findings.
• 8.8. Diminished activity of porphobilinogen synthase in nearly all family members of both patients. From these investigations it can be concluded that there is no exogeneous, “toxic” cause of this porphyria. Porphobilinogen synthase in lead poisoning is not diminished to such an extent as demonstrated here; in contrast to lead intoxication, porphobilinogen synthase activity cannot be activated or reactivated by thiols. All clinical and pathobiochemical data point at a new enzymatic type of endogeneous acute hepatic porphyria with intermittent acute manifestations, clinically analogous to so-called acute intermittent porphyria. Porphyrin precursors and porphyrin excretion both reflects the enzymatic defect and the regulatory consequences starting with the induction of δ-aminolevulinic acid synthase.

     

Cellular and intracellular localization of catalase and acid phosphatase in the midgut of Lumbricus terrestris L.: A cell fractionation study

• 1.1. Cellular and intracellular localization of catalase and acid phosphomonoesterase in the midgut of Lumbricus terrestris was studied by use of tissue fractionation.
• 2.2. At least 60–70% of the catalase resides in the chloragocyte cytosol and the remaining 30–40% resides in gut epithelium peroxisomes.
• 3.3. One of the main functions of the chloragocyte catalase is probably scavenging for H₂O₂ arising from the interaction between blood heme-protein and oxygen.
• 4.4. A simple method for the histochemical detection of cytosol catalase is proposed.
• 5.5. About 10% of the gut acid phosphatase resides in chloragocyte lysosomes. The chloragosomes contain no acid phosphatase.

     

Seasonal changes of circulating blood parameters in the grass snake Natrix natrix natrix L.

• 1.1. Seasonal changes of circulating blood parameters of Natrix n. natrix were evident and involved both sexes to the same extent.
• 2.2. A significant decrease in red cell count, haematocrit and haemaglobin concentration in the mating period, and an increase in those parameters and mean cell volume in autumn were observed, and haemodilution during winter torpor.
• 3.3. The changes during the breeding season had probably a hormonal background; in winter, they resulted first of all from a decreased erythropoietic activity and, to a lesser extent, from an increased red blood cell breakdown rate. However, the possibility that some erythrocytes were withdrawn from the circulation cannot be excluded.
• 4.4. Winter lymphocytopenia, eosinocytopenia and neutrophilic granulocytosis in females during egg laying were expressions of changes of leucocyte formula.
• 5.5. Seasonal cyclicity was found only with respect to the white cell count in males and the eosinophile fraction in males and females.
• 6.6. Probable reasons for, and mechanisms of the changes in blood composition are discussed.

     

Haematology of the australian eastern quoll,Dasyurus viverrinus

• 1.1. A variety of haematological parameters were determined in adult Dasyurus viverrinus.
• 2.2. Haemoglobin and red cell counts were high with a very low mean cell volume.
• 3.3. Basophils are absent but the eosinophils contain small numbers of basophilic granules which may indicate a dual role for this cell.
• 4.4. “Ring Form” leucocytes are present.
• 5.5. Three types of red cell picture could be identified, some animals showing large numbers of spherocytes, spicule cells, and inclusion bodies.
• 6.6. These cells resemble those found in some inherited human haemolytic anaemias but there was no evidence of haemolysis in the animals.
• 7.7. An alkali resistant haemoglobin component is present.

     

The effect of d2o on glycolysis by rat hepatocytes

• 1.1. The effect of incorporating D₂O into the incubation medium on glycolysis and gluconeogenesis by hepatocytes from fasted rats was examined.
• 2.2. The substitution by heavy water, D₂O, at concentrations from 10 to 40%, stimulated glucose uptake, lactate production and CO₂ yields from glucose. At 10 mM glucose, 40% D₂O doubled glucose uptake, increased CO₂ production by 40%, and increased lactate production by 350%.
• 3.3. The stimulation of lactate production decreased at higher glucose concentrations, but was still substantial even at 80 mM glucose.
• 4.4. There was no effect on CO₂ production above glucose concentrations of 30 mM.
• 5.5. Ten percent D₂O showed little inhibition of lactate uptake, its oxidation and gluconeogenesis. At 40% D₂O the inhibition ranged from 10 to 20%.
• 6.6. No effect of D₂O on the rate of glucokinase or glucose-6-phosphatase was observed.
• 7.7. The concentration of fructose, 2,6-P was not affected by D₂O

     

Effects of membrane-perturbing drugs and noradrenalin on cAMP accumulation and red cell water content in carp (Cyprinus carpio) red cells

• 1.1. Carp red cells were treated with drugs that affect the cell membranes. The water content of the cells and the accumulation of cAMP in the cells were measured in normoxia and in hypoxia using non-stimulated and adrenergically stimulated cells.
• 2.2. WGA, DIDS + CCCP and A23187 increased the water content of nonstimulated normoxic cells.
• 3.3. In hypoxia ouabain and DIDS + CCCP increased the water content but cytochalasin B, NPM, DIDS, CCCP and A23187 + CA²⁺ abolished the hypoxia-induced swelling.
• 4.4. Any membrane perturbation induced some cAMP formation, Sophora and Anquilla lectins being most potent.
• 5.5. Also in adrenergically stimulated cells, membrane perturbation generally increased cAMP formation.
• 6.6. However, cAMP accumulation diminished in cells treated with cytochalasin B, CCCP and DIDS + CCCP.
• 7.7. The adrenergic swelling of carp red cells was reduced in normoxia by DIDS. NPM and CCCP increased the adrenergic swelling in normoxia to hypoxic level.
• 8.8. In hypoxia WGA and Anquilla lectin decreased the swelling.

     

Depressed baroreceptor-cardiac reflex sensitivity during simulated diving in ducks

• 1.1. The baroreceptor-cardiac reflex was examined in unanesthetized ducks at rest and during diving. In ducks breathing air an inverse relationship between mean arterial blood pressure and heart rate was observed over the pressure range from 80cm H₂O to 290cm H₂O.
• 2.2. Increases in pressure were obtained by bolus intravenous injection of phenylephrine (PE) while the hypotension was achieved by intravenous acetylcholine (ACh).
• 3.3. The inverse relation of blood pressure and heart rate was also observed in ducks without pharmacologic intervention.
• 4.4. The baroreceptor-cardiac reflex sensitivity was -3.13 beats/min/cm H₂O in non-diving ducks and fell to -0.96 beats/min/cm H₂O with PE and ACh derived data.
• 5.5. During diving the baroreceptor-cardiac reflex sensitivity was further reduced to —0.48beats/ min/cm H₂O.
• 6.6. This finding indicates that even during the pronounced bradycardia of diving baroreceptor stimulation continues to influence heart rate.

     

Sodium transport in red blood cells of lamprey LAmpetra fluviatilis

• 1.1. Unidirectional Na⁺ influx in lamprey red blood cells was determined using ²²Na as a tracer.
• 2.2. Total Na⁺ uptake and amiloride-inhibitable Na⁺ influx increased in a saturable fashion as a function of external Na⁺ concentration (Na_e).
• 3.3. At 141 mM Na_e, the average value of net Na⁺ influx was 13 ± 1.1 and the amiloride-sensitive Na⁺ influx was 5.3±1.1 mmol/l cells per hr (±SE).
• 4.4. The amiloride-sensitive component of Na⁺ influx was significantly activated by 10⁻⁵ M isoproterenol, by 2 × 10⁻⁵ M DNP, and by cell shrinkage.
• 5.5. Furosemide (1 mM) had no effect on the Na⁺ transport in red cells.
• 6.6. The residual amiloride-insensitive component of Na⁺ transport was a linear function of Na_e in the range of 5–141 mM. This transport seems to be accounted for by simple diffusion.

     

Variations in response to environmental hypoxia of different colour forms of the shore crab,Carcinus maenas

• 1.1. The oxygen consumption of red and green Carcinus in normoxic and hypoxic sea water was determined, using an oxygen electrode in a sealed respirometer.
• 2.2. The red crabs had significantly higher “excited” oxygen uptake rates and a lower ability to compensate for hypoxia than the green crabs.
• 3.3. Red Carcinus display an emersion response to declining oxygen at lower oxygen tensions than the green crabs.
• 4.4. Mortality of red crabs exposed to prolonged anoxia was much greater.
• 5.5. The relationship of these findings to the zonation of the two colour forms on the shore is discussed.

     

δ-Aminolevulinic acid dehydratase inactivation by uroporphyrin I in light and darkness

• 1.1. The action of uroporphyrin I on erythrocytic ALA-D activity under dark and light conditions was examined.
• 2.2. Photo and non-photoinactivation of ALA-D induced by uroporphyrin I were observed.
• 3.3. Both effects were dependent on uroporphyrin concentration, temperature and time of exposure of the protein to the porphyrin.
• 4.4. Light-dependent effect of uroporphyrin I is related with the phototoxicity of porphyrins and could be produced by primary amino acid photooxidation followed by secondary cross-linking of the protein.
• 5.5. Light-dependent effect of uroporphyrin I could be ascribed to a direct enzyme inhibition due to binding of the porphyrin to the protein inducing structural changes at or near its active site.

     

Proteolytic system in Babesia hylomysci

• 1.1. Babesia hylomysci has an aminopeptidase and an acid endoprotease
• 2.2. The amino-peptidase has properties very similar to the aminopeptidase in Plasmodium yoelii nigeriensis and P. chabaudi.
• 3.3. The acid endoprotease is specific towards haemoglobin and practically has no action on bovine serum albumin.
• 4.4. In mouse normal red blood cells we find an acid protease having physico-chemical properties similar to the enzyme present in B. hylomysci extracts.
• 5.5. The similarity of electrophoretic velocity between acid protease in B. hylomysci and non-infected red blood cells leads us to think that the acid protease of parasitic extracts comes from the host-cell.
• 6.6. The proteolytic system of Babesia and Plasmodium are similar.

     

Some aspects of activation and inhibition of rat brain lipoxygenase

• 1.1. Regulatory properties of lipoxygenase activity in rat brain cytosol were studied using linoleic acid (LA) as a substrate.
• 2.2. A change in the absorbance at 234 nm was biphasic when a mixture of LA and pre-formed hydroperoxide (LA-OOH) was incubated with freshly isolated native brain cytosol. Initially, a rapid depletion of LA-OOH was observed with a concomitant formation of LA-oxo compounds. This phase was followed by LA dioxygenation.
• 3.3. Both hydroperoxidase and dioxygenase activities of lipoxygenase were inhibited by micromolar concentrations of classic lipoxygenase inhibitors (phenidone, 5,8,11-eicosatriynoic acid and nordihydroguaiaretic acid).
• 4.4. The dioxygenase activity in dialysed cytsool was stimulated by nanomolar concentrations of H₂O₂ and micromolar concentrations of LA-OOH and it was inhibited by serotonin, dopamine and norepinephrine (IC₅₀ 25–43 μM).

     

Patterns of hemoglobin production in the adult newt (Triturus cristatus) erythron following induction of anemia

• 1.1. Changes in the hemoglobins present in many vertebrates have been observed during development and during anemic episodes.
• 2.2. A change in the number of hemoglobins present and their relative amounts was observed when adult Triturus cristalus newts were made anemic by injection of acetylphenylhydrazine.
• 3.3. Hemoglobin IV, which is a minor hemoglobin in healthy adults, was found to be a major component during the subsequent erythropoietic response to hemolytic anemia.
• 4.4. No new hemoglobin not already present in the non-anemic state was detected during the response to induced anemia.

     

The role of lipoproteins in the delivery of tumour-targeting photosensitizers

• 1.I. Serum lipoproteins play an important role in the in vivo transport of several porphyrinoid derivatives having a moderate or high degree of hydrophobicity.
• 2.2. There appears to exist a correlation between the extent of photosensitizer association with low-density lipoproteins (LDL) and the efficiency of tumour targeting by some classes of photosensitizers, such as differently sulphonated porphyrins and phthalocyanines, haematoporphyrin dialkylethers and unsubstituted phthalocyanines and naphthalocyanines.
• 3.3. In all cases, LDL-carried photosensitizers are preferentially released to malignant cells; hence, direct cell damage appears to be the major determinant of tumour damage consequent to photodynamic therapy.
• 4.4. Present evidence suggests that the LDL-associated photosensitizer is accumulated by tumour cells largely via a receptor-mediated endocytotic process.
• 5.5. Thus, the use of delivery systems for orientating a systemically injected photosensitizer towards lipoproteins has been explored; promising results have been obtained by incorporation of the dye into liposomal vesicles, oil emulsions or inclusion complexes, as well as by precomplexation of the dye with LDL.
• 6.6. Moreover, a suitable choice of the chemical constituents of the delivery system and the experimental conditions allows one to modulate the photosensitizer distribution among the different lipoproteins.
• 7.7. The occurrence of tumour-targeting strategies other than the LDL pathway is briefly discussed.