Factors influencing plasma zinc levels in low-income pregnant women

Plasma zinc (Zn) concentrations were measured in 4376 indigent women (86% African-American), at a mean (±SD) gestational age of 15 (±7.8) wk to determine the relationship between various maternal characteristics and plasma Zn levels during pregnancy. Mean plasma Zn levels were lower in African-American women than in Caucasian women, in multiparous women than in primiparous women, and in women with body weight >69.9 kg than in those with body weight ≤69.9 kg (p≤0.001 for each comparison). There were no significant differences related to maternal age, marital status, education, or smoking habit. Multiple regression analysis, including maternal prepregnancy weight, race, age, parity, smoking habit, education, and marital status indicated that race, parity, and pregnancy weight were significantly associated with maternal plasma Zn levels, adjusted for gestational age. Maternal race was the best predictor of plasma Zn concentrations among the population of pregnant women studied A significant proportion of variance in maternal plasma Zn levels remained unexplained after taking into account various maternal characteristics. The reasons for lower plasma Zn levels in African-American women, compared to Caucasian women, during pregnancy are unknown.     

Patterns of meiotic double-strand breakage on native and artificial yeast chromosomes

The preferred positions for meiotic double-strand breakage were mapped on Saccharomyces cerevisiae chromosomes I and VI, and on a number of yeast artificial chromosomes carrying human DNA inserts. Each chromosome had strong and weak double-strand break (DSB) sites. On average one DSB-prone region was detected by pulsed-field gel electrophoresis per 25 kb of DNA, but each chromosome had a unique distribution of DSB sites. There were no preferred meiotic DSB sites near the telomeres. DSB-prone regions were associated with all of the known ”hot spots” for meiotic recombination on chromosomes I, III and VI. Received: 19 March 1996; in revised form: 26 July 1996 / Accepted: 18 August 1996     

Relationships among the herbicide and functional sites of acetohydroxy acid synthase from Chlorella emersonii

The properties of acetohydroxy acid synthase (AHAS, EC 4.1.3.18) from wild-type Chlorella emersonii (var. Emersonii, CCAP-211/11n) and two spontaneous sulfometuron methyl (SMM)-resistant mutants were examined. The AHAS from both mutants was resistant to SMM and cross-resistant to imazapyr (IM) and the triazolopyrimidine sulfonanilide herbicide XRD-498 (TP). The more-SMM-resistant mutant had AHAS with altered catalytic parameters (K _m, specificity), but unchanged sensitivity to the feedback inhibitors valine and leucine. The second mutant enzyme was less sensitive to the feedback inhibitors, but had otherwise unchanged kinetic parameters. Inhibition-competition experiments indicated that the three herbicides (SMM, IM, TP) bind in a mutually exclusive manner, but that valine can bind simultaneously with SMM or TP. The three herbicide classes apparently bind to closely overlapping sites. We suggest that the results with C. emersonii and other organisms can all be explained if there are separate binding sites for herbicides, feedback inhibitors and substrates.Abbreviations AHAS acetohydroxy acid synthase - AL acetolactate - AHB acetohydroxybutyrate - IM imazapyr - TP triazolopyrimidine sulfonanilide herbicide XRD-498 - R enzyme specificity - SMM sulfometuron methyl This research was supported in part by the United States — Israel Binational Science Foundation (BSF), Jerusalem, Israel (Grant 86-00205) and the Fund for Basic Research, Israel Academy of Sciences.     

Involvement of IHF protein in expression of the Ps promoter of the Pseudomonas putida TOL plasmid.

Regulation of the xyl gene operons of the Pseudomonas putida TOL plasmid is mediated by the products of the downstream clustered and divergently oriented xylR and xylS regulatory genes. The xylR-xylS intergenic region contains the xylR and xylS promoters Pr and Ps, respectively. A binding site for the XylR activator protein is located upstream of Ps and overlapping Pr. DNase I footprint experiments showed that one of these sites, which overlaps the recognition site for XylR activator, as well as an AT-rich region comprising the Ps promoter consensus were protected by integration host factor (IHF). IHF was found to act negatively in the in vivo activation of the Ps promoter, since the activity of a Ps promoter::lacZ fusion was elevated in an Escherichia coli mutant lacking IHF. In contrast, no alteration in the synthesis of XylR protein in the E. coli IHF-deficient mutant was detected.     

Structure determination of N-linked oligosaccharides engineered at the CH1 domain of humanized LL2

Two humanized antibody mutants, hLL2HCN1 and hLL2HCN5, engineeredwith CH₁ domain-appended carbohydrates (CHOs) were generatedto facilitate site-specific conjugation of radionudides andanti-cancer drugs to antibodies. Such site-specific conjugationmay minimize the incidence of immunoreactlvity perturbationas is often observed with random conjugation. Since the compositionsand structures of CHOs are important in determining the chemistry,efficiency, and extent of conjugation, the sequences of theCH₁-appended CHOs were determined by exoglycosidase digestionsand fluorophore-assisted CHO electrophoresis (FACE). The CHOspecies attached at HCN1 and HCN5 sites in hLL2HCN1 and IJLL2HCN5,respectively, were distinct from each other, heterogeneous,and extensively processed. All of these CHOs were corefucosylatedcomplex-type oligosaccharides and contained Gal (galactose)and GlcNAc (N-acetylglucosamine) residues in the outer branches.Some of the outer branches were composed of Gal     

A pharmacologic analysis of the action of platelet-activating factor in the induction of hindpaw edema in the rat

Platelet-activating factor (PAF), a phospholipid product of neutrophils, alveolar macrophages, monocytes, and platelets and an important mediator of inflammatory reactions, was studied for its ability to evoke hindpaw edema in the rat. PAF caused edema, peaking at 1 hr and gradually declining over the next 2 hr. The H₁ and H₂ antihistamines, mepyramine and cimetidine, the serotonin/histamine antagonists, cyrpoheptadine, and the serotonin antagonist, methysergide, were ineffective in reducing PAF-induced paw edema. Indomethacin, acetylsalicylic acid, and dexamethasone did not inhibit the peak edematous response but significant reduction was noted with only dexamethasone at 3 hr. Prazosin and propranolol did not prevent PAF-induced edema, whereas, yohimbine, phentolamine, rauwolscine, verapamil and theophylline partially inihibited edema. Clonidine and guanfacine did not induce edema when injected into the rat hindpaw. These results suggest that PAF elicits edema at₂₊ vascular sites of the rat hindpaw which are partially dependent on extracellular Ca movement, are not due to -1 or -2,-adrenoreceptor stimulation, histamine, serotonin, of photaglandin activity, and demonstrates variable sensitivities to agents blocking Ca²⁺ entry. Inhibition of specific PAF-sensitive receptors await the discovery of specific PAF antagonists.     

A defective conditioned behavior and a defective adenylate cyclase in theDrosophila mutantrutabaga

Summary TheDrosophila X-linked mutantrutabaga (Duerr and Quinn 1982) fails to perform normally in olfactory conditioning paradigms, in spite of being able to sense odorants and shock (Figs. 1–3).rut is capable of forming an association between shock and odorant, but memory decays rapidly; the memory of the mutant following intensive training resembles that of normal flies following very brief training (Fig. 4).rut flies also display in vitro a defective adenylate cyclase activity (Fig. 6). The enzyme in the mutant is responsive to stimulation by a putative neurotransmitter and by a guanyl nucleotide (Fig. 8) but the activity is lower than normal even in the presence of forskolin (Fig. 8) and MnATP (Fig. 9), suggesting that the lesion is closely associated with the function of the catalytic subunit.rut/ + heterozygotes are semi-recessive with regard to both the behavioral defect and the biochemical defect (Figs. 5, 7). The behavioral and the biochemical lesions detected inrut flies are discussed in light of current molecular models of learning.     

A "Point of No Return" in the Cell Cycle of Chlorella

In a Chlorella culture growing synchronously at pH 6.3 undera 12 hr light/12 hr dark regime, DNA replication occurs betweenthe 8th and the 12th hour of the cycle, the main period of proteinand chlorophyll synthesis occurring between the 4th and 12thhour of the cycle. When the culture is transferred to alkalinepH at any time up to the 8 hr of the cycle, autospore releaseis prevented, and the pattern of synthesis of DNA, protein andchlorophyll is altered. However, when the culture is transferredto alkaline conditions after the 8th hour of the cycle, thepattern follows that of a culture growing at pH 6.3 with respectto cell number and volume, as well as protein, chlorophyll andDNA contents. Thus, a transition point seems to occur afterthe 8 hr of the cycle. The existence of such a point was alsodemonstrated by reciprocal experiments in which Chlorella wascultured at an alkaline pH and transferred to pH 6.3 at varioustimes in the cell cycle. ¹ Present address: Applied Research Institute, Ben-Gurion Universityof the Negev, P.O. Box 1025, Beer-Sheva 84110, Israel. (Received October 2, 1981; Accepted January 20, 1982)     

Membranes of rat liver peroxisomes

Summary Membranes of liver peroxisomes from rats fed with clofibrate were purified in a discontinuous gradient using a zonal rotor. The preparation consists of round or oval vesicles mostly devoid of nucleoids with a diameter ranging from 70–700 nm; open sheets are found very infrequently. Mitochondrial profiles as well as vesicles containing cytochemically demonstrable glucose 6-phosphatase are scarce; accordingly, glucose 6-phosphatase is nearly undetectable biochemically. Monoamine oxidase is absent in peroxisomal membranes. Cytochrome b₅ is found in a concentration of 0.3 nmoles/mg protein, an order of magnitude comparable to the content of endoplasmic reticulum membranes. Reduction of this cytochrome with palmitoyl-CoA is possible only after recombination of the membranes with the soluble peroxisomal matrix fraction.     

Cyclic AMP response to prostaglandin E1 in mononuclear cells from peripheral blood and synovial fluid of patients with rheumatoid arthritis.

The cyclic AMP response to prostaglandin E1 (PGE1) was studied in peripheral blood (PB) and synovial fluid (SF) mononuclear cells from patients with rheumatoid arthritis (RA). The PGE1 induced accumulation of cyclic AMP was consistently (7 of 8 patients) less in cell suspensions derived from SF than in suspensions of equivalent numbers of mononuclear cells obtained simultaneously from PB. The high PB/SF cyclic AMP ratio was seen most clearly at the lowest concentration (10(-6)M) of PGE1 tested. There was no correlation between the patients' therapy and cyclic AMP response to PGE1. The high PB/SF cyclic AMP ratio was not accounted for by the presence of platelets in PB cell suspensions.