Quantitative structure-retention relationship studies of odor-active aliphatic compounds with oxygen-containing functional groups

High-quality regression equations (R greater than 0.996) modeling the gas chromatographic retention indices of 115 odor-active compounds on stationary phases of different polarity are generated by using the ADAPT software system. Multiple linear regression techniques are used to describe the statistical relationship between the Kováts retention indices and structure-based molecular descriptors. These descriptors encode topological, geometrical, and electronic features of the molecules. The utility of several new descriptors encoding functions of partial atomic charge and solvent accessible surface area is demonstrated. Quantitative predictions of odor threshold values for a subset of these compounds containing the alcohol functional group are also calculated by using a similar methodology.

Elucidation of the deficiency in two yeast coenzyme Q mutants. Characterization of the structural gene encoding hexaprenyl pyrophosphate synthetase

The assembly of a polyisoprenoid side chain and its transfer to para-hydroxybenzoate are the first two steps of coenzyme Q biosynthesis. In yeast these reactions are catalyzed by hexaprenyl pyrophosphate synthetase and PHB:polyprenyltransferase, respectively. We have screened nine complementation groups of yeast coenzyme Q mutants for the activities of these two enzymes and found two strains deficient in either activity. The strain deficient in hexaprenyl pyrophosphate synthetase activity, C296-LH3, is complemented by the plasmid pG3/T1. When C296-LH3 was transformed with a shuttle vector containing a 2,187-base pair fragment from the genomic insert of pG3/T1, both glycerol growth and hexaprenyl pyrophosphate synthetase activity were restored. The activity of the latter enzyme was higher than that seen in wild-type yeast. The increase in activity could be attributed to a gene dosage effect of the multi-copy plasmid. A 1,419-base pair open reading frame encoding a 52,560-dalton protein was found on the genomic fragment. The size of the RNA transcript and the location of transcriptional initiation indicate that the entire open reading frame is contained within the mRNA. Comparison of the hexaprenyl pyrophosphate synthetase amino acid sequence with amino acid sequences from the related enzyme farnesyl pyrophosphate synthetase show the presence of three highly conserved domains. Within two of the domains is an aspartate-rich motif found invariantly in the amino acid sequences of farnesyl pyrophosphate synthetase from three species and the hexaprenyl pyrophosphate synthetase amino acid sequence reported here. These aspartic acid motifs may comprise binding sites for the allylic and homoallylic substrates. The hydrophobicity profiles of the hexaprenyl pyrophosphate synthetase sequence and the farnesyl pyrophosphate synthetase sequence from rat appear similar. Furthermore, the hydrophobicity correlation coefficient of the comparison of these two sequences indicate with a high degree of confidence (p less than 0.001) that the two proteins will fold into similar three-dimensional structures.

Computerized cataract detection and classification

156 eyes of patients and normal volunteers were classified at the slit lamp into the following pure groups: normal (n = 50), nuclear (n = 39), cortical (n = 33) and PSC (n = 34). The eyes were photographed with the Topcon SL-45 Scheimpflug camera and the images scanned and processed to obtain one dimensional profiles through a 40 x 440 micron axial window. Of the 156 profiles, 90 were used as reference samples and were processed to obtain average profiles. The remaining 66 "unknown" profiles and each of the reference profiles, were classified into the four groups based on their distance from the average profiles in Euclidean space. The system was found to be very sensitive (98%) in detecting the presence of cataracts and specific (100%) in identifying normal, i.e. cataract negative lenses. In classifying pure cataracts into the various classes 98% of answers were correct.

Testis-specific transcription initiation sites of rat farnesyl pyrophosphate synthetase mRNA

A variety of rat tissues were screened at low stringency with a rat farnesyl pyrophosphate (FPP) synthetase cDNA. In testis, an FPP synthetase-related RNA was detected that was larger than the liver FPP synthetase mRNA and was present at very high levels comparable with liver FPP synthetase RNA levels obtained from rats fed diets supplemented with cholestyramine and mevinolin. Sequence analysis of testis cDNA clones, together with primer extension and S1 nuclease experiments, indicated that testis FPP synthetase transcripts contain an extended 5' untranslated region. The 5' extension contained one or two out-of-frame upstream ATGs, depending on the site of transcription initiation. Protein in vitro translation studies indicated that the extended 5' untranslated region may play a role in regulating the translation of the FPP synthetase polypeptide in rat testis. Southern blot analysis with a probe containing both testis and liver 5' untranslated sequences provided evidence that both liver and testis transcripts derive from the same gene. The data suggest that an upstream testis-specific promoter results in the abundant production of FPP synthetase transcripts that are translated at low efficiency; another promoter functions in liver and other somatic tissues and directs the regulated synthesis of shorter discrete transcripts.

Isolation and sequence of the human farnesyl pyrophosphate synthetase cDNA. Coordinate regulation of the mRNAs for farnesyl pyrophosphate synthetase, 3-hydroxy-3-methylglutaryl coenzyme A reductase, and 3-hydroxy-3-methylglutaryl coenzyme A synthase by phorbol ester

We report the isolation and nucleotide sequence of the human farnesyl pyrophosphate synthetase cDNA, an enzyme in the cholesterogenic pathway. Partial cDNAs for the human farnesyl pyrophosphate synthetase were isolated by screening human hepatoma (HepG2) and placental cDNA libraries with the rat liver cDNA for farnesyl pyrophosphate synthetase as a probe. Anchored polymerase chain reaction was used to isolate the 5'-end of the cDNA. The nucleotide sequence of the human farnesyl pyrophosphate synthetase cDNA has high identity (86%) to the rat liver cDNA. Treatment of the human monocytic leukemia cell line THP-1 with phorbol esters led to 2--7-fold increases in mRNA concentrations for the three cholesterogenic enzymes, farnesyl pyrophosphate synthetase, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, and HMG-CoA synthase within 5 h. Immunoprecipitation of radiolabeled cells demonstrated that there was a corresponding increase in the rate of synthesis of all three proteins. The addition of cycloheximide to cells also led to increases in the mRNA concentrations of the three enzymes. Treatment of cells with phorbol esters and cycloheximide resulted in superinduction of all three mRNAs; HMG-CoA synthase mRNA levels increased 35-fold, farnesyl pyrophosphate synthetase 17-fold, and HMG-CoA reductase 16-fold 5 h after treatment. The mRNA levels returned to pretreatment levels by 20 h. Cells were also preincubated in the presence of a lipoprotein-deficient fraction of serum plus mevinolin to induce the levels of the three mRNAs. Addition of phorbol esters and cycloheximide to these derepressed cells led to further increases in the mRNA levels for all three enzymes. These results are consistent with the hypothesis that THP-1 cells contain a short-lived negative transcription factor which regulates transcription of the FPP synthetase, HMG-CoA reductase, and HMG-CoA synthase genes. Phorbol esters also regulate these same genes, presumably by modifying a common negative transcription factor and/or by inducing a positive transcription factor(s).

A new monoclonal antibody to a cell-surface antigen that distinguishes luminal epithelial and myoepithelial cells in the rat mammary gland

A monoclonal antibody (25.5) has been produced that recognises luminal epithelial cells of the rat mammary gland. This antibody together with monoclonal anti-CALLA antibodies, which react with mammary myoepithelial cells, has been used in biochemical, immunocytochemical and flow cytometric studies. Antibody 25.5 bound to proteins of molecular weight 70K and 25K (K = 10(3) Mr) in both the rat milk fat globule membrane and in single cell suspensions prepared from the virgin adult rat mammary gland. Anti-CALLA antibody (J5), recognised a 93–100K protein in the gland extracts, which co-electrophoresed with the CALLA/CD-10 antigen from NALM-6 acute lymphoblastic leukaemia cell line. Antibody 25.5 bound to the luminal surface of rat mammary epithelial cells at all stages of development from neonatal through to pregnancy, lactation and involution. CALLA immunoreactive staining has previously been shown on basally located presumptive myoepithelial cells at all stages of development. Flow cytometric analyses demonstrated that 25.5 and anti-CALLA antibodies stained independent cell populations in suspensions of single cells prepared from purified epithelial elements from the mammary gland of adult virgin rat.

Dispersed family of human genes with sequence similarity to farnesyl pyrophosphate synthetase

Prenyltransferases are a group of enzymes involved in the biosynthesis of both sterol and nonsterol isoprene compounds. Somatic cell hybrid studies and in situ hybridization show that the human genome contains five distinct loci that hybridize to the cDNA for the enzyme farnesyl pyrophosphate synthetase (FPS), a prenyltransferase that catalyzes the synthesis of an intermediate common to both the sterol and the nonsterol branches of the isoprene biosynthetic pathway. The loci identified in this report may correspond to unique prenyltransferase genes related to FPS or to pseudogenes. The loci mapped have been identified as farnesyl pyrophosphate synthetase-"like"-1 (FPSL-1) on chromosome 1q24-31, FPSL-2 on chromosome 7, FPSL-3 on chromosome 14, FPSL-4 on chromosome 15q14-q21, and FPSL-5 on chromosome Xq21-22. Multiple copies of sequences similar to those of FPS are also present in both the mouse and the rat.

Coordinate regulation of 3-hydroxy-3-methylglutaryl-coenzyme A synthase, 3-hydroxy-3-methylglutaryl-coenzyme A reductase, and prenyltransferase synthesis but not degradation in HepG2 cells

Human hepatoma HepG2 cells were used to demonstrate coordinate regulation of three enzymes of cholesterol synthesis under a variety of conditions. Addition of either delipidized serum and mevinolin or low density lipoprotein, 25-hydroxycholesterol, or mevalonic acid to HepG2 cells resulted in rapid changes both in the levels of the mRNAs and in the rates of synthesis of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase, HMG-CoA reductase, and farnesyl pyrophosphate synthetase (prenyltranferase). In all cases, the changes in mRNA levels were paralleled by changes in the rates of specific protein synthesis. Pulse-chase techniques were used to determine the half-lives of all three proteins. Addition of low density lipoprotein to the media during the chase increased the rate of degradation of HMG-CoA reductase 4.6-fold but had no affect on the half-lives of HMG-CoA synthase or prenyltransferase. Therefore, we conclude that the coordinate regulation of these three enzymes under a variety of conditions occurs at the level of enzyme synthesis and not at the level of protein stability.

Developmental changes in the expression of genes involved in cholesterol biosynthesis and lipid transport in human and rat fetal and neonatal livers

Cloned cDNAs encoding a number of enzymes involved in cholesterol biosynthesis as well as extracellular and intracellular lipid transport were used to compare the developmental maturation of these biologic functions in the fetal and neonatal rat and human liver. The results of RNA blot hybridization analyses indicate that steady-state levels of rat HMG-CoA synthase, HMG-CoA reductase and prenyl transferase mRNAs are highest in late fetal life and undergo precipitous (up to 80-fold) co-ordinate reductions immediately after parturition. These changes reflect the ability of the fetal rat liver to produce large quantities of cholesterol as well as the repression of this function during the suckling period in response to exogenous dietary cholesterol. Striking co-ordinate patterns of HMG-CoA synthase, reductase and prenyl-transferase mRNA accumulation were also observed in four extrahepatic rat tissues (brain, lung, intestine and kidney) during the perinatal period. The concentrations of all three mRNAs in the 8-week-old human fetal liver are similar to those observed throughout subsequent intrauterine development with less than 2-fold changes noted between the 8th through 25th weeks of gestation. Analysis of the levels of human apo AI, apo AII, apo B and liver fatty acid binding protein mRNAs during this period and in newborn liver specimens also indicated less than 2-3-fold changes. These observations suggest that the 8-week human liver has achieved a high degree of biochemical differentiation with respect to functions involved in lipid metabolism/transport which may be comparable to that present in 19-21 day fetal rat liver. Further analysis of human and rat fetal liver RNAs using cloned cDNAs should permit construction of a developmental time scale correlating hepatic biochemical differentiation to be constructed between these two mammalian species.

The association of posterior capsular lens opacities with bilateral acoustic neuromas in patients with neurofibromatosis type 2

This study of 47 patients from 11 families with neurofibromatosis type 2 (NF 2) confirms our previously reported association between posterior capsular cataract and NF 2. A highly significant statistical association was found between the presence of posterior capsular lens opacities and the presence of NF 2 as determined by magnetic resonance imaging or pathologic diagnosis. This association was not present for other types of lens opacities that could be the result of age-related or nonspecific changes. When considering the diagnosis of NF 2, this finding now makes it essential to use a careful dilated biomicroscopic examination of the lens to evaluate known, suspected, or at-risk individuals for this potentially early associated manifestation.

Identification and regulation of a rat liver cDNA encoding farnesyl pyrophosphate synthetase

CR39 is a cholesterol-repressible rat liver cDNA previously isolated by differential hybridization (Clarke, C.F., Tanaka, R.D., Svenson, K., Wamsley, M., Fogelman, A.M., and Edwards, P.A. (1987) Mol. Cell. Biol. 7, 3138-3146). To precisely identify the function of CR39 a fusion protein was constructed that contained the amino-terminal region of the bacterial protein anthranilate synthetase fused to the full length CR39 polypeptide. Affinity purified antisera directed against the fusion protein inactivated rat liver cytosolic prenyltransferase activity in vitro. In addition, affinity purified antisera made to purified chicken prenyltransferase cross-reacted with the fusion protein containing CR39. Rat hepatic prenyltransferase activity and enzyme mass were quantitated in animals fed diets or drugs known to alter endogenous cholesterol biosynthesis. Rats fed a diet supplemented with cholestyramine and mevinolin showed a 3.5-fold increase in activity and a 5.0-fold increase in mass of cytosolic prenyltransferase. A diet supplemented with cholesterol resulted in approximately a 4.0-fold decrease in hepatic enzyme activity and a 10-fold decrease in enzyme mass. Under these same dietary regimens the mass of prenyltransferase in the testes remained unchanged. We conclude that CR39 encodes the prenyltransferase of cholesterol biosynthesis, farnesyl pyrophosphate synthetase. Furthermore, in the liver this enzyme shows coordinate regulation with two other enzymes, 3-hydroxy-3-methylglutaryl-CoA reductase and 3-hydroxy-3-methylglutaryl-CoA synthase, in response to cholesterol feeding and hypocholesterolemic drugs.

Changes in in vitro growth behaviour of the mammary epithelial cell line NMuMG caused by the v-fos oncogene

A defective retrovirus was constructed to investigate the effect of the expression of the v-fos oncogene from FBJ-MSV on the in vitro growth properties of the mammary epithelial cell line NMuMG. Clearly visible areas of overgrowth in monolayer cultures of NMuMG were seen in cells infected with the v-fos-containing retrovirus but not in cells infected with control virus which did not contain an oncogene. Two cell lines, representing two morphological types of infected cell, were isolated from a morphologically altered region and further characterized. Fos.3.1.NMuMG grew as very spindly cells, achieving a higher density than control cells in 5% foetal calf serum (FCS) but growing very poorly in 1% FCS or in soft agar. Fos.3.3.NMuMG grew to a high density in 5% FCS and to a limited extent in low serum. This cell line also grew in soft agar. Fos.3.3.NMuMG seemed to be more transformed than fos.3.1.NMuMG using the criteria of growth in soft agar and low serum. All the cells used in this study were shown to retain epithelial characteristics by staining for cytokeratins and to contain at least one viral genome by Southern blotting. fos mRNA expression was raised over control levels in the two transformed cell lines.

Reproducibility study on the Scheimpflug Cataract Video Camera

The Zeiss Scheimpflug Cataract Video Camera was designed to photograph, store and analyze cataracts in a semi-automated fashion for cross-sectional and longitudinal studies. We conducted a reproducibility study of this system. Twenty-four normal and 61 cataractous eyes were photographed twice by each of two of the authors in the 90 degree meridian and microdensitometry was performed on each of the stored images. Reproducibility was then determined using the intraclass correlation coefficient to determine whether or not the differences encountered were due to variability in the system or due to actual differences among the images. The intraclass correlation in the lens nucleus was 0.995 with 95% confidence limits of .992-.996. Therefore, reproducibility was 99.5%. In the anterior cortex, intraclass correlation was .941 with 95% confidence limits of .919-.959. In the posterior cortex intraclass correlation was .905 with 95% confidence limits of .870-.932. Reproducibility with this instrument was therefore excellent and with certain limitations, this may be a useful instrument in monitoring lens changes in certain diseases and the effects of anti-cataract agents.

Localization of 3-hydroxy-3-methylglutaryl CoA reductase and 3-hydroxy-3-methylglutaryl CoA synthase in the rat liver and intestine is affected by cholestyramine and mevinolin

In the normal fed rat, both 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) synthase and HMG-CoA reductase are found in high concentrations in hepatocytes that are localized periportally. The majority of the liver cells show little or no evidence of either enzyme. Addition of cholestyramine and mevinolin to the diet resulted in all liver cells showing strong positive staining for both HMG-CoA reductase and HMG-CoA synthase. These two drugs increased the hepatic HMG-CoA reductase and HMG-CoA synthase activities 92- and 6-fold, respectively, and also increased the HMG-CoA reductase activity in intestine, heart, and kidney 3- to 15-fold. We used immunofluorescence and avidin-biotin labeled antibody to localize HMG-CoA reductase in the rat intestine. In rats fed a normal diet, the most HMG-CoA reductase-positive cells were the villi of the ileum greater than jejunum greater than duodenum. Crypt cells showed no evidence of HMG-CoA reductase. Addition of cholestyramine and mevinolin to the diet led to a dramatic increase in the concentration of HMG-CoA reductase in the apical region of the villi of the ileum and jejunum and in the crypt cells of the duodenum. Hence these two drugs affected both the relative concentration and distribution of intestinal HMG-CoA reductase. Cholestyramine and mevinolin feeding induced in the liver, but not intestine, whorls of smooth endoplasmic reticulum that were proximal to the nucleus and contained high concentrations of HMG-CoA reductase. Administration of mevalonolactone led to the rapid dissolution of the hepatic whorls within 15 min, at a time when there is little or no change in the mass of HMG-CoA reductase. We conclude that the whorls are present in the livers of rats fed cholestyramine and mevinolin because the cells are deprived of a cellular product normally synthesized from mevalonate.

Alteration of morphogenesis by the v-myc oncogene in transplants of mammary gland

To see if individual oncogenes can alter three-dimensional growth in vivo, we have inserted the v-myc oncogene into transplants of mouse mammary gland. Primary cultures of mammary epithelial cells were infected with helper-free retrovirus to insert v-myc oncogenes, and transplanted into cleared mammary fat pads (mammary glands from which the natural epithelium had been removed) of host mice. Uninfected transplants, and transplants infected with retrovirus constructs that carry no oncogene, grew to form an epithelial 'tree' resembling normal mammary gland, as expected. Transplants infected with retroviruses carrying v-myc oncogenes grew to form a characteristic, abnormal (hyperplastic) pattern in which the ducts were more densely packed than normal. Integration of the retrovirus in the transplants was demonstrated. The effect of the oncogene was local, not systemic, as some transplants showed adjacent areas of normal and hyperplastic growth. Thus v-myc can alter morphogenesis without growth becoming disorganized.

Macrophage lipoprotein receptors

Macrophages possess a number of surface receptors that are capable of mediating the internalization of lipoproteins. The low-density lipoprotein (LDL) receptor of human monocyte macrophages recognizes apolipoprotein B-100 and apolipoprotein E and is rapidly regulated in response to changes in intracellular cholesterol levels. In contrast, in J774 macrophages LDL receptor regulation is defective and LDL can cause massive cholesterol accumulation. The beta migrating very low density lipoprotein (beta-VLDL) receptor is poorly regulated by cellular cholesterol concentrations, readily recognizes apolipoprotein E, poorly recognizes apolipoprotein B-100, and is immunologically related to the LDL receptor. The scavenger receptor (acetyl-LDL receptor) appears to have a molecular weight of 250,000 and is not regulated by cellular cholesterol levels. This receptor recognizes LDL that has been chemically or biologically altered. LDL complexes can also enter macrophages and cause cholesterol accumulation. Examples of such complexes are LDL-dextran sulphate complexes, LDL-proteoglycan aggregates, LDL-mast cell granule complexes, LDL-heparin-fibronectin-denatured collagen complexes, and LDL-antibody complexes. The entry of lipoprotein into macrophages by a pathway that is poorly regulated or is not regulated by cellular cholesterol concentrations appears to be a prerequisite for the formation of arterial foam cells.

A comparative study between the PAM and the laser interferometer in cataracts

We conducted a prospective study on 35 consecutive eyes undergoing cataract extraction to compare the Guyton-Minkowski Potential Acuity Meter (PAM) and the Laser Interferometer (LI) in determining potential visual acuity. The eyes were divided into: group A, which had good visualization of optic disc details, and group B, whose media allowed only disc outline or less to be seen. We found that in group A eyes, both instruments were reliable (with accuracies of 94% for the PAM and 88% for the LI). However, in group B eyes (advanced cataracts), both instruments were unreliable (accuracies of 33% for the PAM and 53% for the LI). Interestingly, in a subgroup of high myopes (axial length greater than 29 mm) with moderate cataracts and poor visual acuties, both instruments were very reliable and helpful in determining how much of the vision loss was due to the cataracts. We therefore strongly recommend potential acuity testing in high myopes with moderate cataracts and poor visual acuity.