Viscoelastic breakup in a high velocity airstream

Viscoelastic fluids were injected into a high velocity airstream (200 m/s) to investigate how the addition of small polymer quantities to fluids significantly increase the resultant disseminated drop size. For each liquid tested several hundred resultant drops were sampled and measured using an automated image analyzer. The resultant mass median diameter (MMD) for a viscoelastic fluid was an order of magnitude larger than a comparable viscous Newtonian fluid. A relaxation time measured from a die swell experiment correlates the dissemination results suggesting, an elongational rather than shear breakup mechanism.     

Action of endo-alpha-N-acetyl-D-galactosaminidase on synthetic glycosides including chromogenic substrates

The synthetic glycosides, p-nitrophenyl- and o-nitrophenyl-2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl-alpha- D-galactopyranosides, were found to be effective chromogenic substrates for an endo-alpha-N-acetyl-D-galactosaminidase. We did not experience any problems when these substrates were used for the screening of column fractions during the purification of the endoenzyme from Diplococcus pneumoniae culture filtrates. However, it should be pointed out that a combination of exo-beta-galactosidase, capable of cleaving beta 1-->3 linkages, and an exo-alpha-N-acetyl galactosaminidase would also liberate nitrophenol from the above substrates. The enzyme had no action on several other synthetic glycosides tested indicating the strict specificity of this enzyme for the disaccharide Gal beta-->GalNAc linked via an alpha-linkage to the aglycone. The enzyme was inactive when the aglycone was methanol but shows activity against the glycosides of phenol, nitrophenols, serine, and threonine. The use of p-nitrophenyl-2-acetamido-2-deoxy-3-O-beta -D-galactopyranosyl-beta-D-galactopyranoside, which is a competitive inhibitor of the endoenzyme, as an affinity ligand for the purification of the enzyme is described.     

Characterisation of Trypanosoma cruzi populations by DNA polymorphism of the cruzipain gene detected by single-stranded DNA conformation polymorphism (SSCP) and direct sequencing

Fifty fresh isolates of Trypanosoma cruzi from Triatoma dimidiata vectors and 31 from patients with Chagas' disease were analysed for DNA polymorphisms within the 432-bp core region of the cruzipain gene which encodes the active site of cathepsin L-like cystein proteinase. The cruzipain gene showed signs of polymorphism consisting of four different DNA sequences in Central and South American isolates of T. cruzi. The PCR fragments of Guatemalan isolates could be divided into three groups, Groups 1, 2 and 3, based on different patterns of single-stranded DNA conformation polymorphism. All of the strains isolated from Brazil, Chile, and Paraguay, except for the CL strain, showed a Group 4 pattern. Two to four isolates from each group were analysed by cloning and sequencing. A silent mutation occurred between Groups 1 and 2, and five nucleotides and two aa substitutions were detected between Groups 1 and 3. The DNA sequence of Group 4 contained five nucleotides and one aa substitution from Group 1. All of the DNA sequences corresponded well with the single-stranded DNA conformation polymorphism. The Group 1 isolates, the majority in the Guatemalan population (70/81, 86.4%), were isolated from both triatomines and humans, but Group 3 were isolated only from humans. Moreover, the Group 2 isolates were detected only in triatomine vectors (9/50; 18%), but never in humans (0/32, P<0.05) suggesting that this group has an independent life-cycle in sylvatic animals and is maintained by reservoir hosts other than humans.     

In vivo semen-associated pH neutralization of cervicovaginal secretions

To determine (1) the relationship between primary hyperparathyroidism with mild hypercalcemia and psychiatric disturbances, bone density, or non-specific symptoms, and (2) the effect of parathyroidectomy on these outcomes, a systematic and critical review of the literature was conducted. Relevant citations were identified using MEDLINE (1966 to August, 1995) and PsycINFO (1967 to August, 1995). Studies were included for the overview if they described patients with mild hypercalcemia (< 12 mg/dl), and if they dealt with at least one of the following outcomes: psychiatric disturbances, bone density, joint pain, constipation, polyuria/nocturia or weight loss. Either a calculated effect size or Z score was used to estimate the effect of the disease or parathyroidectomy on these outcomes. Seven studies met the inclusion criteria for this overview. Two out of three case-control studies on psychiatric symptoms found a significant association between primary hyperparathyroidism with mild hypercalcemia and psychiatric disturbances (effect sizes; 0.17, 1.2 and 1.6). One of the three studies also examined the effect of parathyroidectomy on psychiatric symptoms, and found an effect size of 1.5. All four cross-sectional studies that measured bone mass showed significantly reduced bone density in the forearm and the lumbar spine. The bone loss ranged from 0.9 to 1.4 standard deviation below the age- and sex-adjusted mean value in the forearm, and was 0.5 in the spine. There was no relevant study regarding non-specific symptoms. Among the seven studies, five did not explicitly indicate whether the patients had classical symptoms of either osteitis fibrosa cystica or renal stones. Primary hyperparathyroidism with mild hypercalcemia is associated with psychiatric disturbances and reduced bone density. Nevertheless, further research is needed to determine the symptoms, particularly for a group of patients without either classical bone disease or renal stones. The effects of parathyroidectomy on these outcomes also remain to be determined.     

Correlation analysis between phenolic levels of Brazilian propolis extracts and their antimicrobial and antioxidant activities

Propolis extracts are currently used for the treatment of oronasal infections and as antioxidant agents. Ethanolic commercial Brazilian propolis extracts were assayed for their ability to inhibit the growth of Staphylococcus aureus and also for their ability to scavenge DPPH radicals. These activities were correlated with their total phenolic and flavonoid levels. In one group of extracts there was a strong linear relationship between total phenol contents and the measured activities, while in the other group this relationship was weaker. It was also found that flavonoid levels had a greater influence on the antioxidant activity of these extracts than on their antimicrobial profiles.