Effects of lanthanum in cellular systems

Lanthanum belongs to the group of elements known as “lanthanons,” which also includes cerium, europium, promethium, and thulium. It is the most electropositive element of the rare earth group, is uniformly trivalent, and is similar in its chemical properties to the alkaline earth elements. The effects of this element and its compounds on cellular systems are of considerable interest because of their increasing use in industry and as a substitute or antagonist for calcium in a variety of cellular reactions. Lanthanum is also being employed extensively in studying anatomical barriers, membrane structure, and subcellular transport systems, particularly the calcium pathway.     

Aggravation of cholesterol induced hyperlipidemia by chronic vitamin C deficiency: experimental study in guinea pigs

Chronic vitamin C deficiency was induced in guinea pigs by restricting their vitamin C intake to 0.5 mg daily. This was just sufficient to prevent rapidly fatal scurvy and 55 per cent of the animals survived. In 16 weeks their serum ascorbic acid (SAA) fell to 0.16 +/- 0.06 mg/dl as compared to 0.73 +/- 0.11 in control animals receiving 5 mg vitamin C daily. There was a marked increase in serum cholesterol, LDL-cholesterol, VLDL-cholesterol, triglycerides and total lipids. HDL-cholesterol was, however, decreased resulting in a shift of the LDL/HDL ratio from 1.13 +/- 0.16 in the control to 5.91 +/- 1.70 in the low vitamin C group. Cholesterol feeding (100 mg/day) by itself lowered the SAA significantly, besides producing hyperlipidemia. When the vitamin C intake was reduced to only 0.5 mg/day, the effects of cholesterol feeding were exaggerated; the magnitude of hyperlipidemia was now significantly greater than with simple cholesterol feeding. The LDL/HDL ratio rose to 19.02 +/- 3.32 from 1.13 +/- 0.16 in the normal guinea pigs. Chronic vitamin C deficiency seems to affect the blood lipid profile unfavourably which could promote atherogenesis.     

A new case of Robertsonian translocation in cattle

A new Robertsonian translocation was found in several animals of the Blonde d'Aquitaine breed. The fused chromosome analyzed by G- and R-banding results from the fusion of chromosomes 21 and 27. C-banding suggests that the fused chromosome is dicentric.     

X-linkage of malic enzyme in Anopheles culicifacies species B

A survey for malic enzyme (Me) in laboratory strains of species A and species B of Anopheles culicifacies had uncovered two electrophoretic variants, slow and fast, in two strains of species B. Genetic analysis revealed the two variants to be codominant alleles segregating at a locus, Me, which is sex linked. Because of the XX-XY sex determining mechanism, in F1 females, two electromorphs, viz., slow and fast, were observed, whereas in males only one electromorph of maternal origin was seen. Linkage experiments with another X-linked mutant, white eye (w), indicated the map distance between the two loci to be 9.52 +/- 0.86.     

Chromosomal aberrations induced by cobaltous chloride in mice in vivo

The effects of cobaltous chloride in inducing chromosomal aberrations were observed on laboratory bred mice in vivo after single oral administration of different fractions (1/10, 1/20, 1/40) of the lethal toxic dose of the salt. Bone marrow cells were flushed out and processed for chromosome studies following colchicine, hypotonic, giemsa, air drying procedure. The parameters screened were chromosomal aberrations, with and without gaps and break per cell. Slides were screened after the expiry of 6, 12, 18, and 24 h. Statistical analysis indicated the clastogenic effects of the salt. The degree of chromosome damage was directly related to the concentration, and also to the period after administration. The different stages of the cell cycle were affected.     

Biodegradation of textile azo-dyes byPhanerochaete chrysosporium

Of 18 commercially used textile dyes, eight were degraded by the white rot fungus,Phanerochaete chrysosporium, by 40 to 73% based on decrease of colour. Both the lignin-degrading enzyme system ofP. chrysosporium and adsorption to its cell mass were involved in the degradation of the diazo dye, Reactofix Gold Yellow. Degradation was best achieved by adding the dye to the medium and then inoculating with pre-grown mycelium; inoculation with spores resulted mainly in dye adsorption.     

Effects of T-2 toxin and its congeners on membrane functions of cultured human fibroblasts

Cytotoxicity of T-2 toxin, HT-2 toxin, acetyl T-2, neosolaniol, and T-2 tetraol was compared between normal human fibroblasts and mutant I-cell human fibroblasts, which only produce 10 to 15% of lysosomal hydrolases present in normal fibroblasts. Both cleavage of 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and cell count by hemocytometer were used for evaluations. For all toxins, dose-related effects on both types of cultures were evident. Cytotoxicity of the above mycotoxins on both cell lines were similar, indicating that lysosomal enzymes were not involved in the toxicity of T-2 toxin and its congeners. An inhibitor of lysosomal cysteine proteases (E-64) did not alter the cytotoxicity of T-2 toxin. The decreasing order of toxicity was T-2 toxin, HT-2 toxin, neosolaniol, acetyl T-2 toxin, and T-2 tetraol in both cell lines. When normal human fibroblasts were loaded with the fluorescent dye Lucifer yellow CH (LY), a subsequent treatment of T-2 toxin did not disrupt lysosomal membranes. The uptake of LY was not affected by T-2 toxin, which indicated that T-2 toxin did not interfere with the endocytic pathway. Results indicate that T-2 toxin and its congeners do not exert their primary toxic effect through lysosomal enzymes, membranes, or via the endocytic pathway.     

Resonance Raman spectroscopy of amicyanin, a blue copper protein from Paracoccus denitrificans

The copper binding site of amicyanin from Paracoccus denitrificans has been examined by resonance Raman spectroscopy. The pattern of vibrational modes is clearly similar to those of the blue copper proteins azurin and plastocyanin. Intense resonance-enhanced peaks are observed at 377, 392, and 430 cm-1 as well as weaker overtones and combination bands in the high frequency region. Most of the peaks below 500 cm-1 shift 0.5-1.5 cm-1 to lower energy when the protein is exposed to D2O. Based on the pattern of conserved amino acids, the axial type EPR spectrum, and the resonance Raman spectrum, it is proposed that the copper binding site in amicyanin contains a Cu(II) ion in a distorted trigonal planar geometry with one cysteine and two histidine ligands and an axial methionine ligand at a considerably longer distance. Furthermore, the presence of multiple intense Raman peaks in the 400 cm-1 region which are sensitive to deuterium substitution leads to the conclusion that the Cu-S stretch is coupled with internal ligand vibrational modes and that the sulfur of the cysteine ligand is likely to be hydrogen-bonded to the polypeptide backbone.     

Higher incidence of spontaneous sister-chromatid exchanges (SCEs) and X-ray-induced chromosome aberrations in peripheral blood lymphocytes during pregnancy

In vitro cultures of peripheral blood lymphocytes from human and muntjac (barking deer) females who were at an advanced stage of pregnancy (32-37 weeks pregnant women and 20-24 weeks pregnant muntjacs) showed an enhanced frequency of SCEs and X-ray-induced chromosome aberrations when compared with those of nonpregnant females. Lymphocyte cultures of nonpregnant females to which sex hormones progesterone, oestrogen and human chorionic gonadotropin (HCG) were added together exogenously also showed higher frequency of SCEs. The plausible reason(s) for such high incidence of SCEs during pregnancy is discussed.     

Platelet count on slow induction to high altitude

Platelet counts were estimated at sea level in 50 lowlanders. They were divided at random in two groups (A and B) of 25 each. Group A went up by train/road transport to 3658 m, while group B reached the same height after 8 days of acclimatisation enroute. Platelet counts were estimated serially in both groups at high altitude. Symptoms of high altitude exposure were also recorded. No significant change in the counts was noted in either group and none became Symptomatic. All were brought back to sea level by air and deinduction studies carried out on days 1 and 4 of return. The importance of these findings in the light of our existing knowledge is discussed.