Culture change and epidemiological patterns among the Hagahai,Papua New Guinea

The role of introduced epidemic disease in highland New Guinea is considered in light of recent debate concerning pre-contact adaptations. Seroepidemiological studies of the Hagahai, a small isolated group of hunterhorticulturalists in the fringe highlands of Papua New Guinea, document the recent introduction of mumps, hepatitis B, specific types of influenza, and rotavirus. Results are related to ethnographic findings, detailing past levels of intergroup contact and recent changes in settlement patterns, travel, feasting, health care, and other cultural factors. Data suggest that intergroup disease transmission is greatly increased decades before officially recorded time of contact and that mortality levels documented soon thereafter are not indicative of the pre-contact adaptation.     

Development of thermotolerance and changes in intracellular pH in CHO cells heated at 45.0 degrees C at pH 6.6

Chinese hamster ovary (CHO) cells were given short heat pulses (5 to 20 min) at 45.0 degrees C and incubated at 37 degrees C for up to 20 h under either pH 7.3 or 6.6 conditions. Thermotolerance developed under both pH conditions, but at a slower rate in the pH 6.6 medium. Intracellular pH (pHi) was measured with the dye, 1,4-diacetoxy-2,3-dicyanobenzene, combined with flow cytometry. Time-dependent changes in the intracellular pH occurred under either pH condition. CHO cells incubated under normal pH conditions had a transient increase in the pHi. This pHi elevation was followed by a rapid intracellular acidification of approximately 0.15 to 0.25 pH units. The timing of both the increases and decreases in the pHi was dependent on the magnitude of the initial heat dose. With heat doses less than or equal to 10 min, the pHi returned to normal unheated levels after the acidification phase. Although cells incubated under low pH (6.6) conditions showed similar pHi alterations, differences in the kinetics were measured. The intracellular pH increased immediately after heating. In addition, when intracellular acidification occurred, the rate of acidification was significantly reduced. With heat doses longer than 5 min under the low pH conditions, the pHi did not return to normal unheated levels.     

Intracellular pH measurements using flow cytometry with 1,4-diacetoxy-2,3-dicyanobenzene

1,4-Diacetoxy-2,3-dicyanobenzene (ADB) has been increasingly used for measurement of intracellular pH by flow cytometry. ADB rapidly enters cells and is cleaved to the fluorescent pH indicator 2,3-dicyano-hydroquinone (DCH). We have analyzed several potential problems that can affect its usefulness as a pH indicator. Hydrolysis of ADB in aqueous solutions reveals the temporary presence of a fluorescent species blue-shifted from DCH at the same pH. The presence of this species with DCH can lead to erroneous pH measurements. Stable pH measurements with ADB depend on the incubation conditions and esterase activity. Heated cells required 20 min for stable measurements, whereas control cells required 5 to 10 min. The reproducibility of pH measurements was excellent, with a resolution of less than or equal to 0.05 pH units in the range of 6.4 to 8.0. Absolute calibration curves of intracellular pH using the ionophore nigericin depended on matching the intracellular K+ concentration with the buffer, but relative measurements of intracellular pH were insensitive to K+. ADB was nontoxic to Chinese hamster ovary cells at up to 20 micrograms/ml. However, when cells loaded with dye were passed through a UV laser beam, concentrations of dye greater than 5 micrograms/ml were highly toxic. Viable cells could be sorted on the basis of intracellular pH if ADB were used at low concentrations.     

The Escherichia coli biotin biosynthetic enzyme sequences predicted from the nucleotide sequence of the bio operon

The nucleotide sequence of the biotin (bio) biosynthetic operon of Escherichia coli has been determined. The 5.8-kilobase region contains the five biotin operon genes, bioA, B, F, C, and D. and an open reading frame of unknown function. The operon is negatively regulated and divergently transcribed from a control region between the bioA and bioB genes. The product of the bioA gene, 7,8-diaminopelargonic acid aminotransferase, was discovered to be related to ornithine aminotransferase. The product of the bioF gene, 7-keto-8-aminopelargonic acid synthetase, was found to be similar to 5-aminolevulinic acid synthetase.     

Micronuclei and the cytoplasm of growing Tetrahymena contain a histone acetylase activity which is highly specific for free histone H4

Salt extracts prepared from purified micronuclei and the cytoplasm of growing Tetrahymena contain a histone acetylase (also referred to as histone acetyltransferase) activity which is highly specific for H4 when tested as a free histone. With both extracts, H4 is acetylated first at position 4 (monoacetylated) or positions 4 and 11 (diacetylated), sites diagnostic of deposition-related acetylation of newly synthesized H4 in vivo. As the concentration of cytosolic extract is decreased in the in vitro reactions, acetylation of H3 is also observed. Neither activity acetylates histone in a chromatin form. These activities are distinct from a macronuclear acetylase which acetylates H3 and H4 (macro- or micronuclear) equally well as free histones and which acetylates all four core histones when mononucleosomes are used as substrate. As well, the micronuclear and cytoplasmic activities give similar thermal-inactivation profiles which are different from that of the macronuclear activity. In situ enzyme assays demonstrate a macronuclear-specific activity which acetylates endogenous macronuclear chromatin and an independent micronuclear-cytosolic activity which is able to act upon exogenously added free H4. These results argue strongly that an identical acetylase is responsible for the micronuclear and cytoplasmic activity which is either modified or altogether distinct from that in macronuclei.     

Phosphatidylcholine metabolism in cultured cells: catabolism via glycerophosphocholine

The catabolism of phosphatidylcholine (PtdCho) has been studied in cultured murine neuroblastoma (N1E-115), C6 glioma, rat brain primary glia, and human fibroblast cells. Cells were pulse labelled for 96 h with [methyl-3H]choline followed by a chase for up to 24 h in medium containing 4 mM choline. Measurement of the radioactivity and mass of choline-containing compounds in these cells indicated that the major degradative pathway is PtdCho----lysophosphatidylcholine (lysoPtdCho)----glycerophosphocholine (GroPCho)----choline. At all times during the chase, PtdCho, sphingomyelin and lysoPtdCho comprised 72-92% of the cell-associated radioactivity; the remaining 10-30% was water-soluble and was chiefly GroPCho (30-80%) in all cell lines. In fibroblasts, however, phosphocholine (PCho) was also a major labelled water-soluble component (33-54%). The specific activity of GroPCho closely parallelled that of PtdCho in fibroblasts, but decreased faster than PtdCho in C6 and N1E-115 cells. We postulate that this may be due to distinct pools of PtdCho in the cell with differing rates of turnover. The changes in specific activity of PCho suggest that the major portion is formed by synthesis rather than as a degradative product. However, the inability to reduce the specific activity of this fraction to that of the intracellular choline suggests that a portion may be derived from either PtdCho or GroPCho.     

Active site mapping of the serine proteases human leukocyte elastase, cathepsin G, porcine pancreatic elastase, rat mast cell proteases I and II. Bovine chymotrypsin A alpha, and Staphylococcus aureus protease V-8 using tripeptide thiobenzyl ester substrates

The primary subsite specificities of human leukocyte elastase, cathepsin G, porcine pancreatic elastase, rat mast cell proteases I and II, bovine chymotrypsin A alpha, and the protease from strain V-8 of Staphylococcus aureus have been mapped with a series of tripeptide thiobenzyl ester substrates of the general formula Boc-Ala-Ala-AA-SBzl, where AA represents one of 13 amino acids. In addition, the effects of a P2 Pro and P4 methoxysuccinyl and succinyl groups were investigated. In an attempt to introduce specificity and/or reactivity into the substrate Boc-Ala-Ala-Leu-SBzl(X), the 4-chloro-, 4-nitro-, and 4-methoxythiobenzyl ester derivatives were studied. Enzymatic hydrolyses of the substrates were measured in the presence of 4,4'-dithiobis(pyridine) or 5,5'-dithiobis(2-nitrobenzoic acid), which provided a highly sensitive assay method for free thiol. The thio esters were excellent substrates for the enzymes tested, and in many cases, the best substrates reported here have kcat/KM values higher than those reported previously. The best substrate for human leukocyte elastase was Boc-Ala-Pro-Nva-SBzl(Cl), which has a kcat/KM of 130 X 10(6) M-1 s-1. A very reactive rat mast cell protease substrate, Boc-Ala-Ala-Leu-SBzl(NO2), was also found. The S. aureus V-8 protease was the most specific enzyme tested since it hydrolyzed only Boc-Ala-Ala-Glu-SBzl. Substituents on the thiobenzyl ester moiety of Boc-Ala-Ala-Leu-SBzl resulted in decreased KM values with human leukocyte elastase and rat mast cell protease I when compared to the unsubstituted derivative.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intrinsic Bacterial Contamination of a Commercial Iodophor Solution: Investigation of the Implicated Manufacturing Plant

After an outbreak of peritoneal infections attributed to intrinsic contamination of a poloxamer-iodine solution with Pseudomonas aeruginosa, the manufacturer of the contaminated solution permitted investigation and sampling of materials within the plant. Pseudomonas spp. were recovered from two different unopened lots of solution and from numerous water samples obtained at the plant. The isolates from water identical to those of an isolate recovered from Prepodyne solution (West-Agro Chemical Co., Inc., Westwood, Kans., manufactured for AMSCO Medical Products Div., Erie, Pa.) manufactured 1 month earlier at the same plant. P. aeruginosa was not recovered from incoming city water. P. aeruginosa was recovered from sterile water and poloxamer-iodine after 48 h of incubation in a plant polyvinyl chloride pipe. Scanning electron micrographs of polyvinyl chloride pipe used in the plant showed massive concentrations of rod-shaped and coccobacillary cells apparently embedded in interior deposits of the pipe. Manufacturers of iodophors should be aware that pipes or other surfaces colonized with bacteria may be a source of contamination of their products.     

2-Chloro-4-amino-1,3,5-triazine-6(5H)-one: a new intermediate in the biodegradation of chlorinated s-triazines.

Pseudomonas sp. strain A grew with 2-chloro-1,3,5-triazine-4,6-diamine as the sole and growth-limiting source of nitrogen. The substrate was utilized quantitatively and concomitantly with growth and with excretion of a product which was identified as 2-chloro-4-amino-1,3,5-triazine-6(5H)-one. The reaction yielded 1 mol of organic product and 1 mol of NH4+ per mol of substrate.