UDP-galactose:globotriaosylceramide alpha-galactosyltransferase activity in rat pheochromocytoma (PC12h) cells

The activity of alpha-galactosyltransferase in cultured rat pheochromocytoma subcloned (PC12h) cells was examined using Gb3 as the acceptor for the galactose from UDP-galactose. The major reaction product was identified as gal alpha 1-3Gb3 based on its mobility on thin-layer chromatographic (TLC) plates and susceptibility to specific galactosidases. The enzyme activity in PC12h cells was the highest at pH 7.0 while the presence of Triton CF-54 (0.1%) and Mn2+ (5 mM) was required for its full activity. The apparent Km values for Gb3 and UDP-galactose were 57 and 17 microM, respectively. The enzyme activity in PC12h cells was compared with that in parent PC12 cells, in which gal alpha 1-3Gb3 is not expressed in an appreciable amount. In the enzyme reaction with exogenous Gb3, the enzyme activity in PC12h cells was about 1.5-fold higher than that in PC12 cells. In the absence of exogenous Gb3, this difference became even more pronounced; gal alpha 1-3Gb3 was generated from endogenous Gb3 at a much higher rate in PC12h cells than in PC12 cells. These findings suggest that the higher level of the alpha-galactosyltransferase activity in PC12h cells may, at least in part, be responsible for the accumulation of unique neutral glycosphingolipids having gal alpha 1-3 terminal residues in the cells.

Sequence of the gene encoding the major outer membrane protein of the mouse pneumonitis biovar of Chlamydia trachomatis

The gene encoding the major outer membrane protein of the Chlamydia trachomatis mouse pneumonitis biovar was sequenced and the amino acid sequence deduced. The primary structure of this protein is similar to that of the lymphogranuloma venereum and trachoma biovars in that it consists of four variable domains interspersed with five constant domains. This protein may be an ideal candidate for a vaccine in chlamydia-infected mouse experimental models.

Effects of different types of polyunsaturated fatty acids on cholesterol esterification in human fibroblasts

We have enriched human fibroblasts with oleic acid, with linoleic acid and with eicosapentaenoic acid. The accumulation of cholesteryl esters in the cells and the rate of esterification of cholesterol by microsomal acyl-CoA:cholesterol acyltransferase (ACAT) were measured in these cells. Cholesteryl ester levels were lower in cells enriched with eicosapentaenoic acid compared with cells enriched with oleate or linoleate. We also observed significantly lower ACAT activities in the microsomes from fibroblasts enriched with the n-3 polyunsaturated fatty acids relative to cells enriched with oleic acid or linoleic acid. We suggest that the presence of n-3 polyunsaturated fatty acids might suppress cholesteryl ester accumulation and inhibit atherogenesis.

Investigation on phosphate dependent glutaminase (EC 3.5.1.2) activity in host tissues of EAC-bearing mice and response of liver EC 3.5.1.2 on Cu-ATP therapy

Phosphate-dependent glutaminase activity in spleen, kidney, brain and liver is increased after tumor cell inoculation and this activity gradually increases with the progression of the tumor. The increase in enzyme activity in the liver is significant. Studies of the response of liver glutaminase after Cu-ATP treatment reveals that Cu-ATP is capable of reducing the high glutaminase level in subjects with malignant tumors to the normal level.

An experimental study on the effect of nifedipine on ischaemic skin flap survival in rats

Vasodilators have been employed previously in an attempt to improve survival of ischaemic rat skin flaps. The effect of nifedipine, a calcium channel blocker, on skin flap survival was studied using a standard experimental rat model. The control group had a mean flap necrosis of 37.009%. Rats treated by nifedipine starting 1 day preoperatively and continued for 1 week postoperatively had a mean necrosis of 10.0953%. Rats treated by nifedipine started postoperatively and continued for 1 week had a mean flap necrosis of 12.289%. Treated groups had significantly lower flap necrosis in comparison to untreated controls. There was no significant difference in flap necrosis between the two treated groups. This study shows that nifedipine improves survival in standard ischaemic rat skin flaps.

Studies on the anti-ulcer activity of a Bryophyllum pinnatum leaf extract in experimental animals

A methanolic fraction from an extract of Bryophyllum pinnatum leaves was found to possess significant anti-ulcer activity in nine different experimental animals models. Premedication tests in rats revealed that the extract possessed significant protective action against the gastric lesions induced by aspirin, indomethacin, serotonin, reserpine, stress and ethanol. Significant protection with extract treatment was observed to occur for aspirin-induced ulcer in pylorus-ligated rats and for histamine-induced duodenal lesions in guinea pigs. Significant enhancement of the healing process was also found to occur in acetic acid-induced chronic gastric lesions in rats.

Proteoglycans of bovine articular cartilage. The effects of divalent cations on the biochemical properties of link protein

In cartilage proteoglycan aggregates, link protein stabilizes the binding of proteoglycan monomers to hyaluronate by binding simultaneously to hyaluronate and to the G1 globular domain of proteoglycan monomer core protein. Studies reported here involving metal chelate affinity chromatography demonstrate that link protein is a metalloprotein that binds Zn2+, Ni2+, and Co2+. Zn2+ and Ni2+ decrease the solubility of link protein and result in its precipitation. However, link protein is readily soluble and functional in low ionic strength solvents from which divalent cations have been removed with Chelex 100. These observations make it possible to study the biochemical properties of link protein in low ionic strength, physiologic solvents. Studies were carried out to define the oligomeric state of link protein alone in physiologic solvents, and the transformation in oligomeric state that occurs when link protein binds hyaluronate. Sedimentation equilibrium studies demonstrate that in 0.15 M NaCl, 5 mM EDTA, 50 mM Tris, pH 7, link protein exists as a monomer-hexamer equilibrium controlled by a formation constant of 2 x 10(27) M-5, yielding a delta G' of -36 kcal/mol for the formation of the hexamer from six monomers. On binding hyaluronate oligosaccharides (HA10 or HA12), link protein dissociates to dimer. Link protein hexamer is rendered insoluble by Zn2+. Greater than 90% of the protein is precipitated by 2 mol of Zn2+/mol of link protein monomer. The binding of hyaluronate oligosaccharide by link protein strongly inhibits the precipitation of link protein by Zn2+. The link protein/hyaluronate oligosaccharide complex is completely soluble in the presence of 2 mol of Zn2+/mol of link protein. At higher molar ratios of Zn2+/link protein, the inhibitory effect of hyaluronate oligosaccharide on the precipitation of link protein is gradually overcome. Hyaluronate oligosaccharide is not dissociated from link protein by Zn2+. Hyaluronate remains bound to the link protein which is precipitated by Zn2+, or to the link protein which binds to Zn2(+)-charged iminodiacetate-Sepharose columns. Hyaluronate oligosaccharides and Zn2+ bind to different sites on link protein.

Study of serum myoglobin and serum electrolytes in acute uncomplicated myocardial infarction

Forty patients with uncomplicated acute myocardial infarction were studied within 6-18 hours after the infarction. Serum myoglobin was elevated in all the cases and was markedly high in cases studied 18 hours after the acute infarction, though the level did not show any relation with the severity of the attack. Myoglobin level showed no correlation with SGOT level, which did not rise appreciably within 6 hours. Serum sodium and potassium levels did not show any change, even in the most severe cases. Serum myoglobin estimation is thus a good diagnostic test in the early hours of acute myocardial infarction.

N-3 polyunsaturated fatty acids enhance cholesterol efflux from human fibroblasts in culture

Normal human skin fibroblasts were incubated in medium supplemented with 60 micrograms/ml linoleic acid (18:2n6) or eicosapentaenoic acid (20:5n3). After five days, cells lipids were enriched with linoleic acid or with docosapentaenoic acid (22:5n3). The HDL-mediated efflux of cholesterol from cells enriched with n-3 polyunsaturated fatty acids (PUFAs) was twice as fast as the rate of efflux of cholesterol from cells enriched with n-6 PUFAs. This suggests that the fatty acid composition of cellular lipids affects cholesterol efflux. The faster efflux when cells contain n-3 PUFAs may account for part of the reduction in risk of coronary disease with increases in dietary n-3 PUFAs (fish oils).

Immunologic and survival studies in mice immunised with cryodestroyed ascites fibrosarcoma (AFS) cells

Adult mice weighing 20 g, divided into 5 groups, were immunised with single and three cycle cryodestroyed ascites fibrosarcoma cells using different modes of immunisation with respect to dose and administration frequency. Survival against subsequent challenge with the same tumour cells and immune response given by leucocyte migration inhibition, were studied in these animals. It appears from the present study that animals with relatively low antigenic load have a significantly (P less than 0.001) high mean survival time and/or survival index compared with controls than those with relatively high antigenic load. Survival in animals immunised with three cycle cryodestroyed tumour cells is significantly (P less than 0.001) higher than that with single cycle even in face of a greater challenging tumour dose with mode of immunisation remaining the same. Preliminary observations on percentage leucocyte migration inhibition showed that there exists no difference in percentage inhibition with either viable or cryodestroyed tumour cell antigens added to migration chamber excepting in animals immunized with three cycle cryodestroyed tumour cells where percentage inhibition was significantly (P less than 0.001) greater with viable than with cryodestroyed tumour cell antigen without altering the percentage inhibition between the two groups. Factors maximising immune response and their modulating effects are discussed.

Chlamydial heat shock proteins and trachoma

Two chlamydial proteins (HSP-60 and HSP-70) have marked homology with bacterial and mammalian heat shock proteins. Previous studies have indicated that when inoculated into the eyes of immune animals, a Triton X-100 extract of chlamydia containing HSP-60 induces an ocular delayed-type hypersensitivity reaction. The potential for HSP-70 to induce a similar reaction was tested in six cynomolgus monkeys that had been sensitized to both antigens by previous ocular chlamydial infection. Whereas the chlamydial extract containing HSP-60 induced a marked clinical response within 24 h of inoculation, no response followed inoculation of HSP-70 in the contralateral eye. The lack of a response to HSP-70 suggests that further assessment of its potential as a trachoma vaccine is warranted.

Prediction of temperature profiles in the human skin and subcutaneous tissues

Exact mathematical solutions in terms of confluent hypergeometric and Airy's functions are obtained to study the steady state temperature distributions in human skin and subcutaneous tissues (SST). It is assumed that the skin is exposed to an air environment and heat transfer from the skin occurs by convection, radiation and evaporation. A mathematical model of the SST, accounting for heat conduction, perfusion of the capillary beds and metabolic heat productions of the dermis and subcutaneous tissues, has been solved to obtain interface temperatures for a wide range of environmental temperatures, rates of evaporation of sweat, wind speeds and relative humidities. The solutions provide inter-relationships between interface temperatures, thermal conductivities, metabolic heat production, blood perfusion, thicknesses of various layers of SST and ambient temperature.

Occurrence and significance of Cryptosporidium infection in Calcutta

During a 2-year study, Cryptosporidium oocysts were detected in 32 (5.6%) of 566 hospitalized paediatric diarrhoea cases and 2 (1.2%) of 167 non-diarrhoeic individuals. Cryptosporidium was the sole pathogen detected in 17 (3.0%) of the 32 positive cases; in the other 15 it occurred in combination with one or more other established enteropathogen(s). The frequency of detection of the parasite was highest in the 0-6 months age group; no sex-specific difference was discernible. The detection rate of the parasite was highest during the monsoon and post-monsoon months. Most of the patients had watery stools with a mild to moderate degree of dehydration, with the diarrhoea lasting for less than 7 d.