The milk of the fur-seal, Arctocephalus tropicatis gazella; in particular the composition of the aqueous phase

Milk and plasma samples from the Southern fur-seal (Arctocephalus tropicalis gazella) , collected from animals shot between 0 and 26 days post-partum , have been analysed. The aqueous phase of milk (ultracentrifugate) was hyperosmotic to plasma by about 35 m-osmol/kg water but contained no lactose. The osmolality of milk could be accounted for by the ionic content, of which sodium and potassium (in approximately equal amounts) were the main cations. The fat content of the milk was very high (approximately 40%), except in very early lactation (0 and 1 day post-partum). The concentrations of chloride, calcium, magnesium, phosphate and citrate in the aqueous phase are given. Major differences between the composition of fur-seal milk and that of other mammals are pointed out, and discussed in relation to water conservation, energy and fat supply, and prolonged milk storage in this snecies.     

Sodium, potassium, calcium, magnesium, zinc, citrate and chloride content of human prostatic and seminal fluid

The ionic composition of human prostatic fluid varied greatly between individuals, reflecting the secretory activity of the gland and the presence or absence of prostatic inflammatory disease. In normal prostatic fluid the major anion was citrate, while chloride concentrations were lower. Their counterions were mainly sodium and potassium, together with calcium, magnesium and zinc. Prostatic secretions from men with prostatitis comprised mainly sodium and chloride. The electrolytes were closely correlated to each other (except for sodium, which was essentially invariant at about 145 nm). The molar changes per mole of citrate were about 0.52, potassium; -0.53, chloride; 0.17, calcium; 0.14, magnesium; and 0.09, zinc. The pH was also associated with citrate, decreasing from 8.0 to 6.2 as the citrate increased. These various ionic changes can be explained as responses to citrate secretion, without the need to propose specific transport mechanisms for the other ions measured. The marked effect of prostatic inflammation on the composition of prostatic fluid can be seen as being due mainly to decreased secretion rather than active modification.     

An equilibrium thermodynamic model of the sequestration of calcium phosphate by casein micelles and its application to the calculation of the partition of salts in milk

An equilibrium thermodynamic model of the interaction of calcium, phosphate and casein in milk is described in which the micellar calcium phosphate is assumed to be in the form of calcium phosphate nanoclusters. A generalized empirical formula for the nanocluster is used to define the molar ratios of small ions (Ca, Mg, P_i and citrate) to a casein phosphorylated sequence (phosphate centre, PC). From this model, a method of calculating the partition of milk salts into diffusible and non-diffusible fractions is obtained. No arbitrary assumptions are made, no fitting of adjustable parameters is done and the PCs in the caseins are defined by inspection of their primary structures. In addition to the salt partition, the mole fractions of the individual caseins not complexed to the calcium phosphate through one or more of their PCs are computed and a generic stability rule for milks is derived. The use of the model is illustrated by calculations of the partition of salts in a standard milk and by comparison with experimental data on the partition of salts in the milk of individual cows. The generic stability rule is applied to the individual milks to determine whether the micellar calcium phosphate is thermodynamically stable. According to the calculations, compositions that might lead to pathological calcification in the lumen of the mammary gland were seldom found in primiparous healthy cows in early or mid lactation but occurred more often in multiparous animals, in late lactation and during mastitic infection.Abbreviations ACP amorphous calcium phosphate - Cit citrate - CN casein - CPN calcium phosphate nanocluster - DCPD dicalcium phosphate dihydrate - HA hydroxyapatite - IAP ion activity product - MCP micellar calcium phosphate - MWCO molecular weight cut-off - OCP octacalcium phosphate - PC phosphate centre - TCC tricalcium citrate     

Haemolymph plasma composition of the Essig''s lupine aphid, Macrosiphum albifrons Essig (homoptera: aphididae)

Haemolymph from the Essig's Lupine aphid, Macrosiphum albifrons (Essig), was analyzed for pH, osmolality, and concentrations of magnesium, calcium, potassium, sodium, chloride, phosphate and citrate. The concentration of inorganic ions and citrate was relatively low forming only 14% of the osmotic potential of the plasma (476 mOsm). The composition of the plasma resembled more the composition of phytophagous Endopterygota than Exopterygota.     

Composition and ultrastructure of calcium phosphate-citrate complexes in bovine milk systems

The present studies show that the colloidal calcium phosphate of cow's milk has a (Ca + Mg)/P_i ratio of 1.67 (± 0.10; n = 22) and contains citrate, Mg and Zn at molar ratios to Ca averaging 0.05, 0.03 and 0.003, respectively. The composition of the natural colloidal phosphate of milk is similar to the precipitates formed by neutralization of ultrafiltrates obtained from acidified milks, and to that of the calcium phosphate-enriched fraction produced by extensive enzymic hydrolysis of the casein micelles in milk. Examination by electron microscopy of these artificial preparations of milk calcium phosphate revealed in both a very fine and uniform substructure which consisted of granules having an average, true diameter of approx. 2.5 nm. The size and shape of these tiny granules closely resemble the morphologies reported for the colloidal phosphate particles in native casein micelles, as well as for the subunits of amorphous calcium phosphate observed during calcification in other biological systems such as mitochondria and bone.     

Effect of various chloride salts on the utilization of phosphorus, calcium, and magnesium

Only part of the effect of dietary protein on urinary calcium excretion can be ascribed to sulfur amino acids. We hypothesized that chloride, another factor often associated with isolated proteins, and another amino acid, lysine, affect utilization of calcium. The effects of supplemental dietary chloride, inorganic or organic, on calcium, phosphorus, and magnesium utilization were studied in two rat studies. Weanling Sprague-Dawley rats were fed semi-purified diets that contained moderate (1.8 mg Cl/g diet) or supplemental (15.5 mg Cl/g diet) chloride as sodium chloride, potassium chloride, or lysine monohydrochloride with or without calcium carbonate for 56 or 119 days. Rats fed supplemental sodium chloride or potassium chloride had higher urinary phosphorus excretion, more efficient phosphorus absorption, but unchanged tissue phosphorus levels after 7 and 16 weeks of dietary treatment as compared to rats fed moderate chloride. Rats fed supplemental sodium chloride or potassium chloride excreted more calcium in urine at 7 weeks and absorbed calcium less efficiently at 16 weeks. Tissue calcium concentrations were unaffected, but total tibia magnesium and plasma magnesium concentrations were lower in rats fed supplemental sodium chloride or potassium chloride than those fed moderate chloride. Lysine chloride with or without additional calcium elevated urinary calcium excretion even more than sodium chloride and potassium chloride ingestion. Rats fed lysine chloride with supplemental calcium had smaller apparent absorption and urinary losses of phosphorus and magnesium after 16 weeks and lower tibia and plasma magnesium concentrations than rats fed lysine chloride.     

Changes in mammary development and composition of secretion during late pregnancy in the mare.

Small samples of mammary secretion were taken for analysis from Thoroughbred mares during the last 3 weeks of pregnancy up to the time of foaling. The concentrations of sodium and chloride decreased while those of lactose, potassium, citrate, phosphate, calcium, magnesium and protein increased. The time-course of these changes showed marked variation between animals. The concentration of whey proteins began to increase about 10 days before parturition. The appearance of the secretion and the size of the mammary glands increased in the last few days of pregnancy. It is suggested that the concentration of calcium in mammary secretion could provide the basis of a test for impending parturition in this species.     

Subcellular distribution of potassium, sodium, magnesium, calcium and chloride in cerebral cortex

The subcellular distributions of potassium, sodium, magnesium, calcium and chloride have been determined for rabbit cerebral cortex. After homogenization and differential centrifugation, the following percentages of ions were associated with the particulate fraction (nuclear, mitochondrial, synaptic vesicles, and microsomal): (a) 19% of the total potassium; (b) 22% of the total sodium; (c) 77% of the total calcium; (d) 69% of the total magnesium; and (e) less than 2% of the total chloride. However, the sum of the potassium and sodium content in each of the particulate fractions was greater than the sum of the calcium and magnesium content. After hypo-osmotic shock of the crude mitochondrial fraction (M_T), more sodium than potassium (μmol/g wet wt.) was associated with the mitochondrial (M₁) and synaptic vesicle (M₂) fractions. The molar ratio of sodium to potassium was 1·4 for M₁ and 4·5 for M₂. The association of ²²Na⁺ with the particulate fractions was further studied by the method of equilibrium dialysis. The data from both types of experiments indicate that a large fraction of the sodium in cortical tissue appears to be in a bound state.     

Sulphur and phosphorus requirements of Curvularia pallescens Boed

The effect of different sulphur and phosphorus compounds on the growth and sporulation ofCurvularia pallescens Boed. has been studied. Nine different sulphur sources were tried but among them only magnesium sulphate yielded the best dry weight of the fungus. Zinc sulphate, sodium sulphate, sodium thiosulphate, potassium sulphate and calcium sulphate supported good growth. Poor growth was recorded on sodium bisulphite, ammonium sulphate, sodium sulphide and control. Sporulation was excellent on magnesium sulphate. It was good on zinc sulphate, sodium sulphate and potassium sulphate. On sodium thiosulphate, calcium sulphate, sodium bisulphite and control it was fair. Sodium sulphide and ammonium sulphate had inhibitory effect as sporulation was poor and nil on these two compounds respectively.Six phosphorus compounds were studied. Tripotassium phosphate gave best growth and excellent sporulation. Good growth and excellent sporulation was recorded on monobasic potassium phosphate and magnesium phosphate. Growth and sporulation were good on dibasic potassium phosphate and sodium dihydrogen phosphate. Ammonium phosphate was poorly utilized.     

Further Investigations on the Nature of the Heat Resistance of Thermophilic Bacteria

When cells of Bacillus stearothermophilus, strain NCA 1503, were grown in tryptone starch broth and subsequently transferred to tris buffer, a fraction of the cells: rapidly died in ttie buffer. This fraction increased with increasing content of calcium chloride in the growth medium. The' addition of sodium, potassium or magnesium chloride to the growth medium had no such effect. The rapid dying of the cells in tris buffer was associated with a leakage of organic material and calcium ions from the cells. The results obtained are probably caused by a damage to the osmotic barrier of the cells during their contact with the buffer. Observations: made during the present investigation and a previous one (Ljunger 1970) indicate that the heat resistance of thermophilic bacteria depends on the maintenance of a high intracellular concentration of free calcium ions.     

Salivary analytes in patients with oral squamous cell carcinoma

Literature data indicates that measurement of certain salivary constituents might serve as a useful diagnostic/prognostic tool in the patients with oral squamous cell carcinoma (OSCC). In 24 patients with OSCC (60 +/- 2.5 yrs) and in 24 controls (24 +/- 3.7 yrs) we have determined levels of salivary magnesium, calcium, copper, chloride, phosphate, potassium, sodium, total proteins and amylase. Sodium, potassium and chloride were determined by indirect potentiometry whereas copper, magnesium and phosphate were determined by atomic absorption spectrophotometry. Total proteins were determined by pyrogalol colorimetric method. Amylase levels were determined by continued colorimetric method. Statistical analysis was performed by use of chi2 test and Spearman's correlation test. The results of this study indicate that the concentrations of sodium and chloride were significantly elevated in patients with OSCC when compared to the controls. However, level of total protein was significantly decreased when compared to the healthy controls. Furthermore, there was a negative correlation between alcohol consumption and total protein concentration in patients with oral carcinoma. We might conclude that in patients with OSCC increased salivary sodium and chloride might reflect their overall dehydration status due to alcohol consumption rather than consequence of OSCC itself.     

Coprecipitation modulates the solubility of minerals in bovine milk

The solubilities of zinc, iron, copper, magnesium, calcium, inorganic phosphate, and citrate in milk decreased when acidic milk preparations were neutralized. In decaseinated bovine milk soluble zinc, iron, and copper were reduced 90%, 60%, and 50%, respectively, as the pH was raised from 4 to 7. Simultaneous precipitation of minerals and citrate was confirmed by analysis of washed precipitate. We propose that the diminished solubilities of zinc, iron, copper, magnesium, and citrate are linked to the precipitation of calcium phosphate through one or more mechanisms of coprecipitation. Such control on mineral solubility may have an impact upon mineral absorption from milk.     

Calcification in insects: The dwelling-tube and midgut of machaerotid larvae (Homoptera)

The dwelling-tubes of machaerotid larvae consist of a mineralized organic scaffolding of mucofibrils. The mineral component accounts for 85 per cent of the dry weight and is composed of calcium, ferrous iron, manganese, magnesium, potassium, sodium, phosphate, carbonate, and chloride and of these the major ions are calcium and carbonate. Ferric iron in the form of ferritin is probably also present.Calcium, manganese, magnesium, and phosphate are derived from spherites secreted by a specialized region of the midgut. Calcium and phosphate are present in the spherites, probably as amorphous tricalcium phosphate. Subsequent to secretion the spherites are slowly dissolved and the calcium is incorporated into the dwelling-tube as calcium carbonate. Thus it appears that within the dwelling-tube calcium phosphate is converted to calcium carbonate.Ferritin and ferrous iron are secreted by another specialized region of the midgut and are also incorporated into the dwelling-tube.     

Statistical optimization of culture media for growth and lipid production of <Emphasis Type="Italic">Botryococcus braunii</Emphasis> LB572

Botryococcus braunii has an outstanding ability to produce lipid; however, it is a slow-growing green microalgae. Statistical optimization of growth media was performed to faster growth and to increase lipid concentration. The effect of media composition on the growth of B. braunii LB572 was examined using fractional factorial design and central composite design. The media components examined include sodium carbonate, potassium phosphate, calcium chloride, magnesium sulfate, ferric citrate, and sodium nitrate. The results indicated that potassium phosphate and magnesium sulfate were major impact factors. The optimum concentrations of potassium phosphate and magnesium sulphate were found to be 0.058 and 0.09 g/L, respectively, for growth and 0.083 and 0.1 g/L, respectively, for lipid production. These values were validated using bubble column photobioreactors. Lipid productivity increased to 0.19 g/L/day in lipid-optimized media, with an average biomass productivity of 0.296 g/L/day and 64.96% w/w. In growth-optimized media, lipid productivity was 0.18 g/L/day, with an average biomass productivity of 0.304 g/L/day and 59.56% w/w.     

Calcium dynamics in idiopathic calcium stone formers

Ionic calcium, calcium binding sites, and other urinary variables were measured in 58 patients with idiopathic calcium nephrolithiasis and 36 normal subjects. The patients showed higher urinary concentrations of calcium. The mean calcium excretion (mmole/24 hr) was 4.45 +/- 0.56 (+/- 1 SEM) in patients and 2.19 +/- 0.22 (+/- 1 SEM) in normal subjects. This difference was highly significant (P less than 0.001). The mean ionic calcium excretion (mmole/24 hr) was 1.90 +/- 0.21 (+/- 1 SEM) for patients and 0.97 +/- 0.12 (+/- 1 SEM) for control subjects. The normal subjects showed significantly higher (P less than 0.01) concentrations and total excretions of magnesium and citrate. Excretory patterns for sodium, potassium, phosphate, and oxalate were not significantly different. The normal subjects had higher mean urinary concentrations of binding sites for calcium ions (23.2 +/- 4.8 mM) than the patients (18.5 +/- 2.9 mM). However, as the patients had higher urinary volumes the difference in the 24-hr excretion of calcium binding sites was not significant statistically. Out of 58 patients 43 (74%) were hypercalciuric. Twenty patients (46%) were categorized as an absorptive group and one patient as a resorptive type, and for the rest of the patients (51%) the mechanism of hypercalciuria remained unidentified. Only two of the control subjects (5%) were found to be hypercalciuric under calcium restricted diet conditions. Though these "control" subjects excreted a high amount of calcium there was no associated increase in the fraction of the calcium in the ionic form (0.37). Patients, however, still had relatively high fractions of ionic calcium (0.48 +/- 0.03).     

Effects of controlled pH on organic and inorganic composition in haemolymph,epidermal tissue and cuticle of mud crab Scylla serrata

Analysis of organic and inorganic compounds in plasma, epidermal tissue and cuticle were accomplished in the intermolt (C3 stage) of crab Scylla serrata incubated in different pH media. Significant changes with similar trends for protein, carbohydrates, glycosaminoglycans (GAG), sulphur, calcium, magnesium, potassium, phosphorus and copper in the plasma suggested higher dissolution in an acidic medium while the deposition increased in alkaline medium. Similar decreases in protein, carbohydrate and GAG in the epidermal compartment were observed from pH 4 to pH 12. However, significantly higher contents of sodium, chloride, potassium, phosphorus, magnesium, sulphur and copper were measured at pH 7.5 with a symmetrical decrease profile in both acidic and alkaline media, resulting from synergistic effects in the osmotic regulation. Clear changes in calcium concentrations were observed with a sharp increase from lower contents at pH 7.5 to higher at pH 12. In the cuticle, the acidic condition induced a significant dissolution of HCl-protein, GAG, calcium and magnesium contents. On the other hand, the alkaline condition induced a significant decrease in carbohydrate, calcium, chloride, sulphur and potassium. A reduction trend is seen for NaOH and H(2)O-protein contents in the cuticle. These observations suggest that GAG and HCl-protein might constitute the most soluble fraction with high affinity for calcium binding and easily removed in acidic conditions. Additionally, it is possible to speculate that the carbohydrates associated with the NaOH and H(2)O-proteins may form an interface between the soluble matrix fraction and the chitin framework. Sulphur groups seem to present a strong linkage role in this interface fraction, maybe only broken by a specific enzyme in extreme alkaline conditions with subsequent release of significant calcium from the shell.     

Ion concentrations in oviduct and uterine fluid and blood serum during the estrous cycle in the bovine

In the bovine up to 40% of embryos die before implantation but despite the importance of ions in oviduct and uterine fluid formation and in gamete, zygote and early embryo development there is very little published information on the ion concentrations of oviduct or uterine fluid. The free anions chloride, phosphate and sulphate and the free cations sodium, calcium, magnesium and potassium were measured in oviduct fluid on days 0, 2, 4 and 6 and in uterine fluid on days 6, 8 and 14 and in corresponding blood samples. Oviduct and uterine fluids were collected in situ. Sodium was 25-fold higher than potassium and 80-fold higher than the other ions and chloride was 10-fold higher than potassium and 40-fold higher than the other ions in oviduct and uterine fluid. Phosphate, sulphate, magnesium, potassium and calcium were at lower concentrations in all fluids. Oviduct calcium and sodium were higher on day 0 than other days. The most striking uterine differences were the higher potassium and lower chloride, sodium and magnesium on day 14 than other days. There were significant positive associations between oviduct and blood chloride, sulphate, magnesium and calcium while only uterine sulphate was positively related to its blood concentration. There was no relationship between fluid secretion rate and no association between the concentrations of systemic progesterone or oestradiol and any ion in oviduct or uterine fluid. The different concentrations and associations between ions in the oviduct, uterus and blood suggest a differential regulation of ion secretion by the oviduct and uterine epithelia.     

The effect of vasopressin upon the excretion of calcium by the sheep.

Vasopressin (140 muU/min) was infused intravenously into 12 conscious merino ewes for 2 hr. Urine flow rate and free water clearance were consistently reduced. There was no effect upon renal plasma flow, glomerular filtration rate or the rate of excretion of sodium, potassium, magnesium, chloride or phosphate. Although all animals received 75 mmol calcium chloride into the rumen on the previous day, five commenced the experiment with calcium excretion rates of less than 1 mumol/min. In these, vasopressin further decreased calcium excretion. In seven animals with calcium excretion rates between 2 and 20 mumol/min vasopressin had no effect upon either total calcium or free ionized calcium excretion rate.     

CALCULATIONS OF BIOELECTRIC POTENTIALS : VI. SOME EFFECTS OF GUAIACOL ON NITELLA

Values have been calculated for apparent mobilities and partition coefficients in the outer non-aqueous layer of the protoplasm of Nitella. Among the alkali metals (with the exception of cesium) the order of mobilities resembles that in water and the partition coefficients (except for cesium) follow the rule of Shedlovsky and Uhlig, according to which the partition coefficient increases with the ionic radius. Taking the mobility of the chloride ion as unity, we obtain the following: lithium 2.04, sodium 2.33, potassium 8.76, rubidium 8.76, cesium 1.72, ammonium 4.05, ½ magnesium 20.7, and ½ calcium 7.52. After exposure to guaiacol these values become: lithium 5.83, sodium 7.30, potassium 8.76, rubidium 8,76, cesium 3.38, ammonium 4.91, ½ magnesium 20.7, and ½ calcium 14.46. The partition coefficients of the chlorides are as follows, when that of potassium chloride is taken as unity: lithium 0.0133, sodium 0.0263, rubidium 1.0, cesium 0.0152, ammonium 0.0182, magnesium 0.0017, and calcium 0.02. These are raised by guaiacol to the following: lithium 0.149, sodium 0.426, rubidium 1.0, cesium 0.82, ammonium 0.935, magnesium 0.0263, and calcium 0.323 (that of potassium is not changed). The effect of guaiacol on the mobilities of the sodium and potassium ions resembles that seen in Halicystis but differs from that found in Valonia where guaiacol increases the mobility of the sodium ion but decreases that of the potassium ion.     

Caseins are cross-linked through their ester phosphate groups by colloidal calcium phosphate

Artificial casein micelles were prepared by adding 30 mM calcium, 22 mM phosphate and 10 mM citrate to sodium caseinate solutions, and the content of the casein aggregates cross-linked by colloidal calcium phosphate was determined by high-performance gel chromatography on a TSK-GEL G4000SW column in the presence of 6 M urea. The content of the casein aggregates cross-linked by colloidal calcium phosphate in artificial whole casein micelles was 48% of total casein, and their relative casein composition determined by high-performance ion-exchange chromatography was 53.1% for alpha s1-casein, 15.8% for alpha s2-casein, 31.1% for beta-casein and 0% for kappa-casein. The order of cross-linking by colloidal calcium phosphate agreed with that of the ester phosphate content of casein constituents. The content of the casein aggregates cross-linked by colloidal calcium phosphate was higher in alpha s1-kappa-casein micelles than in beta-kappa-casein micelles. kappa- and gamma-caseins and dephosphorylated alpha s1-casein were not cross-linked by colloidal calcium phosphate. Although kappa-casein was not cross-linked, chemically phosphorylated kappa-casein, of which the average phosphate content was 8.5 per molecule, was cross-linked. It is concluded that caseins are cross-linked through their ester phosphate groups by colloidal calcium phosphate.