Cloning and characterization of the 5'-flanking region for the mouse phospholipase C-delta1 gene

To date, little is known about the molecular mechanisms controlling the regulation of phospholipase C-delta1 (PLC-delta1) gene expression. To understand the mechanisms responsible for the regulation of PLC-delta1 gene expression, the 5'-flanking region of the mouse PLC-delta1 gene was isolated from a mouse genomic DNA library. Primer extension analysis revealed that there is a single transcriptional start site located at 127 bases upstream from the translation start codon in the mouse PLC-delta1 gene. DNA sequence analysis showed that the sequence around the transcriptional start site is very GC-rich and has no TATA or CAAT boxes. Transient expression of a luciferase reporter gene under the control of serially deleted 5'-flanking sequences revealed that the 160-base-pair region from -622 to -462 upstream of the transcriptional start site includes a positive cis-acting element(s) for the efficient expression of the PLC-delta1 gene. Gel retardation analysis suggests that multiple transcription factors bind to separate sites on the promoter region. Based on these results, our study suggests that the minimal essential region located at -622 to +70 is fully sufficient to confer high-level transcriptional activity and contains high-affinity binding elements for multiple transcription factors.

Clinical manifestations of Korean female gouty patients

In an endeavor to analyse the clinical characteristics of female gout, we reviewed 36 women with gout. Twenty-seven (75%) developed the first symptomatic episode of gout after the onset of the menopause. The mean age at onset of gout was 54.3 years (range 15-87 years). Twenty-two patients (61%) had hypertension, 17 (47%) had renal insufficiency, 13 (36%) used diuretics and 10 (28%) were taking cyclosporine for a renal allograft. Tophaceous gout occurred in 10 patients (27%) and polyarticular involvement was seen in 16 (44%) at initial presentation. Five of nine premenopausal patients were taking cyclosporine and four had renal insufficiency. A comparison with a control group of 72 randomly selected male patients with gout showed that the female patients were frequently receiving diuretics at the time of the attack and had significantly lower mean uric acid excretion, whereas significantly more male patients showed heavy alcohol consumption and precipitating events for an acute attack compared with the female patients. There were no significant differences between the sexes for onset age, hypertension, renal insufficiency, distribution of joint involvement, tophi and mean serum uric acid concentration. The female patients in this study had a lower mean age at onset of gout than in previous studies, which was attributed to the inclusion of renal transplantation patients. Transplantation gout patients receiving cyclosporine lower the mean age at onset of female gout and this is an emerging problem in female gout.

Lasing characteristics of a pendant drop deformed by an applied electric field

The lasing properties of an oval-shaped resonant cavity (ORC) with a continuously variable aspect ratio have been studied. The ORC was formed with a dye-doped pendant drop placed inside a variable static electric field. When the drop ORC was pumped by a nitrogen laser, lasing from the ORC was found to have strong directional emission characteristics and an intensity enhancement factor as great as 19.5. Calculated results of light rays escaping from ORC's by refraction are in good agreement with the experimental data.

Economic and social implications of aging in Singapore

The economic and social impacts of population aging in Singapore are examined, particularly their impact on labor supply and the extent to which traditional family and community care providers can meet the challenges of an aged population. The adequacy of public policy responses, such as the new employment policy and the Central Provider Fund, are explored. Government strategy to shift the burden of care to the family and other community providers is challenged.

Parametric down conversion of X-ray photons

Parametric down conversion of X-ray photons in diamond crystals was detected in two experiments, both using the phase-matching scheme first employed in the X-ray regime by Eisenberger & McCall [Phys. Rev. Lett. (1971), 26, 684-688]. The conversion events were detected by a combination of time-correlation spectroscopy and energy discrimination, using Si drift-chamber detectors. The time-correlation spectra give a direct comparison of the conversion rate over the accidental coincidence rate. Mechanisms for possible detection of false events and ways to cross check against them are discussed in detail.

Performance limits of direct cryogenically cooled silicon monochromators - experimental results at the APS

The successful use of cryogenically cooled silicon monochromators at third-generation synchrotron facilities is well documented. At the Advanced Photon Source (APS) it has been shown that, at 100 mA operation with the standard APS undulator A, the cryogenically cooled silicon monochromator performs very well with minimal (<2 arcsec) or no observable thermal distortions. However, to date there has not been any systematic experimental study on the performance limits of this approach. This paper presents experimental results on the performance limits of these directly cooled crystals. The results show that if the beam is limited to the size of the radiation central cone then, at the APS, the crystal will still perform well at twice the present 100 mA single 2.4 m-long 3.3 cm-period undulator heat load. However, the performance would degrade rapidly if a much larger incident white-beam size is utilized.

Mechanism of silica- and titanium dioxide-induced cytotoxicity in alveolar macrophages

Particles can cause cytotoxicity in pulmonary alveolar macrophages (AM). Several mechanisms to explain this cytotoxicity have been suggested. However, the exact mechanism of particle-induced cytotoxicity in AM remains to be established. Silica and TiO2 produced a concentration-dependent cytotoxicity as evidenced by loss of cell viability and fall in ATP levels. While silica induced a greater cytotoxicity, TiO2 produced a higher reduction in ATP levels. Silica increased the release of LDH, but TiO2 did not affect enzymatic release. TiO2 suppressed succinate-triggered oxygen consumption, whereas silica did not markedly change the effect of succinate on oxygen consumption. Polyinosinic acid (PI), a ligand of the scavenger receptor, inhibited the TiO2-induced fall in ATP content, but could not prevent the effect of silica on cellular ATP content. Data suggest that silica and TiO2 can induce cytotoxicity in AM, probably through different mechanisms.

Purification and characterization of glutamate dehydrogenase as another isoprotein binding to the membrane of rough endoplasmic reticulum

Glutamate dehydrogenase (GDH) was purified from rough endoplasmic reticulum (RER) in rat liver using anion-exchange and affinity chromatography. As GDH has been known as an enzyme that exists mainly in the matrix of mitochondria, the properties of purified GDH were compared with those of mitochondrial GDH. The GDH activity in 0. 1% Triton X-100-treated RER subcellular fraction was nearly the same as intact RER, whereas that of the mitochondrial fraction increased by 50% after the detergent treatment. In kinetic values, in addition, mitochondrial GDH had a higher K(m) value for NADP(+) than NAD(+), whereas the K(m) value for NAD(+) was higher than that for NADP(+) in the case of GDH of RER, which showed a difference in specificity to cofactors. Moreover, when two GDH isoproteins were incubated at 42 degrees C or treated with trypsin, GDH from RER was more stable against heat inactivation and less susceptible to proteolysis than mitochondrial GDH in both cases. In addition, GDH of RER had at least five amino acids different from mitochondrial GDH when sequences of N-terminal and several internal peptide fragments were analyzed. These results showed that GDH of RER is another isoprotein of GDH, of whose properties are different from those of mitochondrial GDH.

Rapid degradation of PrxI and PrxII induced by silica in Rat2 cells

Peroxidases of the peroxiredoxin (Prx) family catalyze the reduction of H(2)O(2) and lipid peroxides. The effects of H(2)O(2), 12-O-tetradecanoylphorbol 13-acetate (TPA), and silica on the abundance of two cytosolic isoforms of Prx (PrxI and PrxII) were examined in Rat2 cells. TPA induces the production of reactive oxygen species (ROS) in various mammalian cell types, and silica induces the production of ROS in Rat2 cells. Whereas H(2)O(2) and TPA did not affect the concentration of PrxI or Prx II, silica triggered a rapid degradation of both Prx enzymes. Silica also induced degradation of the NF-kappaB inhibitor IkappaB-alpha. N-Acetylcysteine and diphenyleneiodonium, both of which inhibit the accumulation of intracellular ROS, each blocked silica-induced degradation of IkappaB-alpha but had no effect on that of the Prx enzymes, suggesting that ROS do not contribute to Prx proteolysis. The silica-induced degradation of Prx enzymes was also insensitive to the proteasome inhibitors MG132 and lactacystin, whereas IkappaB-alpha proteolysis was completely blocked by these inhibitors. Experiments with the Ca(2+) ionophore A23187 indicated that a Ca(2+)-dependent protease such as calpain might contribute substantially to silica-induced degradation of PrxII, but only moderately to that of PrxI. These results indicate that silica increases cellular oxidative stress not only by inducing ROS production, but also by triggering the degradation of Prx enzymes that are responsible for elimination of cellular ROS. Such aggravated oxidative stress might be important in the initial pathogenesis of silica-associated pulmonary diseases.

Imaging of the normal and abnormal pancreaticobiliary system with single-shot MR cholangiopancreatography: a pictorial review

Magnetic resonance cholangiopancreatography (MRCP) is a rapidly evolving non-invasive imaging modality that produces images of the pancreatic duct and biliary tree without the need for intravenous or oral contrast. The images are equivalent to those from endoscopic retrograde cholangiopancreatography (ERCP), but the non-invasive acquisition avoids the morbidity and mortality associated with diagnostic ERCP. Magnetic resonance cholangiopancreatography is indicated in patients who require only a diagnostic ERCP, who fail an ERCP or who are unable to undergo ERCP due to altered post-surgical anatomy. Other evolving indications include triaging of patients with obstructive jaundice into percutaneous or endoscopic management drainage pathways depending on the site, length and nature of the duct obstruction, thereby potentially decreasing the number of failed or unsuccessful ERCP. Pre-operative identification of anomalous biliary anatomy and choledocholithiasis prior to laparoscopic cholecystectomy promise to modify the pre-operative and operative management of the patient in order to minimize the risk of duct injury and unnecessary intra-operative dissection and cholangiography. The advantages of the technique include its non-invasiveness, the absence of contrast administration, its relative operator independence and the ability to evaluate both sides of an obstructed duct, thereby accurately evaluating stricture morphology and length. The disadvantages of MRCP compared to ERCP include its lack of an immediate therapeutic solution to duct obstruction, procedural cost, unit availability and the inability to evaluate patients with pacemakers or ferromagnetic implants.

Molecular cloning and expression analysis of a mouse phospholipase C-delta1

We describe here the molecular cloning and expression analysis of mouse PLC-delta1 (mPLC-delta1), a key enzyme in cell signal transduction. A mouse brain cDNA library was screened in order to isolate the mPLC-delta1 cDNA. The mPLC-delta1 cDNA was 2660 bp in length. The predicted open reading frame encodes a protein of 756 amino acids with an estimated molecular mass of 85 kDa. The deduced amino acid sequence exhibits 96.9% and 92.7% identity with the sequence of rat and human PLC-delta1, respectively. The mPLC-delta1 mRNA was highly expressed in brain, heart, lung, and testis. We found that transcripts of mPLC-delta1 are present in almost all regions of mouse brain examined, implying that the enzyme may play a role in some fundamental cellular process in brain. In male reproductive tract, mPLC-delta1 mRNA was widely expressed in the epididymis as well as in the testis. In situ hybridization studies indicate that distribution of mPLC-delta1 mRNA in mouse testis is discrete and unique. The expression of mPLC-delta1 mRNA was defined in the periphery of each seminiferous tubule, especially in spermatogonia, which might imply that mPLC-delta1 plays a role in proliferation of spermatogonia. To the best our knowledge, this is the first report to demonstrate the high expression of mPLC-delta1 mRNA in spermatogonia of testis. Taken together, these results suggest that mPLC-delta1 may carry out fundamental roles in almost all of mouse tissues, especially in brain and specific roles in testis.

Lipid profiles in untreated patients with rheumatoid arthritis

OBJECTIVE

To investigate lipid profiles in patients with untreated active rheumatoid arthritis (RA) and to assess the relationship of the inflammatory condition of RA with lipid profiles.

METHODS

Forty-two patients with RA and 42 age and sex matched healthy controls were studied. Patients with RA had not been treated with corticosteroid or disease modifying antirheumatic drugs prior to the study. Total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, apolipoprotein A1 (apo A1), apolipoprotein B (apo B), lipoprotein(a) [Lp(a)], and C-reactive protein (CRP) were measured in both groups.

RESULTS

The levels of apo A1 and HDL-cholesterol were significantly lower in patients than in controls (128.5 vs. 151.8 mg/dl, 41.2 vs. 54.9 mg/dl, respectively). The level of Lp(a) was significantly higher in patients than in controls (27.1 vs. 18.0 mg/dl). The ratios of apo B/apo A1, total cholesterol/HDL-cholesterol, and LDL-cholesterol/HDL-cholesterol were significantly higher in patients than in controls (0.82 vs. 0.67, 4.4 vs. 3.4, 2.8 vs. 1.9, respectively). CRP showed a significant correlation with apo A1 (r = -0.44, p<0.01) and HDL-cholesterol (r = -0.35, p<0.05).

CONCLUSION

Our study suggests that patients with untreated active RA have altered lipoprotein and apolipoprotein patterns that may possibly expose them to higher risk of atherosclerosis. The inflammatory condition of RA may affect the metabolism of HDL-cholesterol and apo A1.

Elevated serum interleukin-15 levels in systemic lupus erythematosus

Interleukin-15 (IL-15) has multiple biological properties, including the induction of other cytokine production and the inhibition of T cell apoptosis. Recently, IL-15 was reported to have a major role in synovial inflammation of rheumatoid arthritis, and that it provokes and amplifies the inflammatory process through the activation of TNF-alpha production. In systemic lupus erythematosus (SLE), the dysregulation of apoptosis and various cytokine production were observed and have been implicated in the pathogenesis of SLE. Thus, we tried to determine serum IL-15 levels in SLE patients and to assess the relationship among IL-15 levels, TNF-alpha levels and disease activity of SLE. Twenty SLE patients and 10 controls were studied. Paired serum samples were collected from all SLE patients at the time of presentation with active disease and at 4 weeks after institution of treatment. IL-15 levels were determined by ELISA and compared with the disease activity indices in SLE. The disease activity of SLE was measured using the SLE Disease Activity Index (SLEDAI) and laboratory parameters such as circulating immune complex (CIC), C3, C4, anti-DNA antibody, IgG, IgM, and IgA. The IL-15 levels in SLE patients were significantly higher than those of controls (5.38 +/- 4.89 vs. 1.04 +/- 1.26 pg/ml). However, elevated IL-15 levels did not correlate with the SLEDAI, nor did they correlate with other laboratory activity indices. The changes in serum IL-15 levels did not correlate with the changes in serum TNF-alpha in the disease course of SLE patients, whereas TNF-alpha reflected the changes in disease activity of SLE. Serum levels of IL-15 are elevated in SLE patients, but IL-15 did not correlate with the disease activity of SLE. TNF-alpha production in SLE patients was unlikely to be related with IL-15.

Silica increases cytosolic calcium and causes cell injury in renal cell lines

The purpose of this study was to clarify the effect of silica-induced cytosolic free calcium mobilization and cell injury in immortalized cell lines from transgenic mice kidney harboring SV40 T-antigen gene. The proximal convoluted tubule (S1)- and the inner medullary collecting tubule (IMCT)-originated cell lines were used. Cytosolic free calcium concentration ([Ca2+]i) was measured employing Fura-2 fluorescence and cell injury was evaluated by a vital dye exclusion procedure. Silica increased [Ca2+]i in a concentration-dependent manner in S1 (60 micrograms/ml-600 micrograms/ml) and IMCT (6 micrograms/ml-600 micrograms/ml). Silica caused a biphasic increase in [Ca2+]i which was composed of an initial rapid rise and following sustained phase. Ca2+ removal from the medium resulted in abolishment of initial and sustained phase of silica (600 micrograms/ml)-induced [Ca2+]i in both cell lines. Silica-induced cell injury was increased in a dose-dependent manner. This silica-induced cell injury was attenuated by the pretreatment with EGTA (100 microM) and nifedipine (1 microM). Cellular ATP content ([ATP]i) by silica also decreased in a concentration-dependent manner. The relationship between [Ca2+]i and [ATP]i showed that [ATP]i depletion caused [Ca2+]i to rise. This study suggests that 1) the elevation of [Ca2+]i caused by silica is due mainly to influx through plasma membrane Ca2+ channel and non specific membrane damage (at high concentration) and 2) nephrotoxicity of silica shows site-specificity within the kidney.

Invasiveness of Helicobacter pylori into human gastric mucosa

BACKGROUND

Helicobacter pylori has generally been observed only in the gastric mucous layer or in the spaces between gastric mucus-secreting cells and not in the gastric epithelial cells or in the lamina propria. The purpose of this study is to determine whether H. pylori invades the gastric mucosa, using an immunoelectron microscopical examination of human gastric mucosa infected with H. pylori.

MATERIALS AND METHODS

Five hundred gastric antral biopsy specimens were fixed in a periodate-lysin-paraformaldehyde solution, embedded in Lowicryl, sectioned, and examined with a light microscope. One hundred specimens moderately or severely infected with H. pylori were selected and were incubated with polyclonal rabbit anti-H. pylori antibody. The specimens were washed, incubated with 20 nm of colloidal gold-conjugated goat anti-rabbit IgG, stained with uranyl acetate and lead citrate, and observed with a transmission electron microscope.

RESULTS

In one case, a bacterium was observed within the cytoplasm of a gastric mucus-secreting cell; in another case, a few bacteria were observed within the cytoplasm of a stromal cell in the lamina propria. The bacteria could be differentiated from degenerated intracellular organelles by gold particles attached to the bacteria.

CONCLUSION

H. pylori rarely invade the lamina propria and gastric cells.

A Mechanistic Approach to Modeling Single Protein Adsorption at Solid-Water Interfaces

A kinetic model for single component protein adsorption which can be readily extended to adsorption from multi-protein solutions was developed, and used to simulate adsorption of site-directed, structural stability mutants of bacteriophage T4 lysozyme. The model allows for two different adsorbed "states," distinguished by different binding strengths and different occupied areas. The presence of an increasing energy barrier to adsorption was incorporated into the model by formulating the adsorption rate constants as functions of time. Numerical analysis was performed using the Marquardt method. Estimated model parameters were consistent with the effect of structural stability on adsorption. In particular, kinetic parameters were such that adsorption into the more tightly bound, conformationally altered state was favored by less stable variants. Copyright 1999 Academic Press.

Evaluation of the degree of cross-linking in UV irradiated porcine valves

A porcine heart valve was irradiated by Ultraviolet (UV) rays (10 W, 254 nm) for 2, 4, 8 and 24 hours at 4 degrees C to cross-link the structural collagen matrix. The degree of cross-linking was evaluated by assaying the released amount of hydroxyproline (Hyp) from the matrix, and comparing it with the positive controls of valves treated by glutaraldehyde (GA) solution (0.625 wt%) and the negative controls of non-treated fresh valves. The undigested weight ratio of the specimens increased by increasing the UV irradiation time. The undigested weight of the leaflets, tunica interna and tunica externa of the fresh, GA-treated and UV-irradiated specimens after collagenase digestion was compared. As UV irradiation increased, the amount of released hydroxyproline was gradually decreased until 8 hours of irradiation, after which the released hydroxyproline-reduction occurred slightly until 24 hours of irradiation time in this system. A total 47.68% of the hydroxyproline in the valve was cross-linked by UV irradiation after 24 hours, while 73.74% of the hydroxyproline in the positive control was crossed-linked. Light microscopic observation revealed that the typical crimp pattern of collagen fibers decreased and was rearranged into a dense flattened pattern as the UV irradiation induced interfibrilar cross-linking. GA-treated valves demonstrated a denser matrix pattern than the UV-irradiated specimens. Cross-linked collagenous tissue prepared by UV irradiation would be useful for improving durability and reducing the disadvantages related to using a chemical cross-linking agent.

[Possibility in unification of oriental and western medicine education by combination of educational curricula]

The authors attempted a possibility of unification in the educational curricula of both Oriental and Western medical schools for the unification of two medicines. Historically the two medicines were originated from the most primitive state like instinctive method and we can say two medicines were entirely the same. However, after abrupt and current development of science in the 19th century by discovery of microscope and bacteria as well as cells, changed medicine into recent unbelievable current medicine from old ancient style medicine like Chinese Medicine which was just the remnant old medicine. The unification of educational curricula is thought to be possible to combine each other by technical adjustment from mutual understanding and cooperation for the most high quality of peoples lives. There were good equality to partial correspondences between two educational curricula around 90% at two pre-and schools from the study to analyse. The combined medicine is thought to be more efficient to the diagnosis and treatment of patients because of the effectiveness of Oriental medicine in certain disease conditions like chronic illness by acupuncture as a alternative medicine or herbs.

Multi-drug resistance (MDR1) gene expression in de novo acute leukemia cells: correlations with CD surface markers and treatment outcome

One important mechanism of drug resistance in acute leukemia is the overexpression of the multi-drug resistance (MDR1) gene that encodes a 170-kDa membrane protein called P-glycoprotein. To estimate the incidence and role of MDR1 gene expression in patients with acute leukemia, we investigated the expression of MDR1 by using the RT-PCR method in blast cells from 40 cases of de novo acute leukemia. We found a high frequency of MDR1 gene expression: 10 out of 20 with de novo acute myeloid leukemia (AML), 8 out of 17 with de novo acute lymphoblastic leukemia (ALL), and none of the 3 with de novo acute mixed leukemia, were MDR1 mRNA-positive. No correlation between cluster designation (CD) surface markers (CD19, CD7, CD13, CD33, CD34, CD14, HLA-DR) and MDR1 gene expression in AML was found. The complete remission rate was correlated with MDR1 gene expression. Among 40 evaluable patients examined, 17% (3 of 18) with MDR1 mRNA-positive reached complete remission versus 77% (17 of 22) with MDR1 mRNA-negative (p=0.044). These results suggest that MDR1 gene expression can be used as a prognostic factor and may be helpful in determining chemotherapeutic protocol for patients with acute leukemia.

Genetics of experimental hypertension

Experimental models of genetic hypertension are used to develop paradigms to study human essential hypertension while removing some of the complexity inherent in the study of human subjects. Since 1991 several quantitative trait loci responsible for blood pressure regulation have been identified in various rat crosses. More recently, a series of interesting quantitative trait loci influencing cardiac hypertrophy, stroke, metabolic syndrome and renal damage has also been described. It is recognized that the identification of large chromosomal regions containing a quantitative trait locus is only a first step towards gene identification. The next step is the production of congenic strains and substrains to confirm the existence of the quantitative trait locus and to narrow down the chromosomal region of interest. Several congenic strains have already been produced, with further refinement of the methodology currently in progress. The ultimate goal is to achieve positional cloning of the causal gene, a task which has so far been elusive. There are several areas of cross-fertilization between experimental and human genetics of hypertension, with a successful transfer of two loci directly from rats to humans and with new pharmacogenetic approaches which may be utilized in both experimental and clinical settings.

Cloning and analysis of the Epstein-Barr virus glycoprotein 350 genes

Membrane glycoprotein 350 (gp350) of the Epstein-Barr virus (EBV) is considered as a major target for vaccine development, since the gp350 has been identified as the virus' mediator for receptor interaction and as an inducer of specific in vitro virus-neutralizing antibodies. In an initial attempt to develop an effective DNA vaccine against an EBV infection, gp350 genes were isolated from SNU-20 and SNU-1103 which are the EBV-infected lymphoblastoid cell lines established in Korea. In addition, the nucleotide sequences of the gp350 genes were determined and compared with those of other EBV strains such as B95-8, P3HR-1/AG876 and M81. Sequence analysis showed that similar high degrees of homology between 2 EBV strains derived from African Burkitt's lymphoma, P3HR-1 and AG876, was shown between the gp350 genes isolated from 2 EBV-infected lymphoblastoid cell lines established in Korea. Furthermore, these 2 Korean and 2 African strains displayed nearly identical patterns of sequence variations from B95-8. In addition, the sequence of the isolated gp350 genes, which have been reported to be associated with the biology of EBV infection, is analyzed.

Magnetic resonance cholangiopancreatography: non-invasive imaging for the biliary tree and pancreatic duct

Producing images similar to those acquired by the invasive procedures of endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography, magnetic resonance cholangiopancreatography (MRCP) is indicated in patients who are unable to undergo ERCP or have had previously unsuccessful ERCP. It is used increasingly in non-invasive evaluation of the pancreaticobiliary tree in cases where the need for intervention during ERCP is expected to be low. MRCP may help in identifying anomalous biliary anatomy or choledocholithiasis before laparoscopic cholecystectomy, and in deciding between percutaneous or endoscopic treatment for patients with obstructive jaundice to decrease the rate of failed ERCP procedures.

Identification of a common low density lipoprotein receptor mutation (C163Y) in the west of Scotland

Familial hypercholesterolaemia (FH) is an autosomal codominant disorder characterised by high levels of LDL cholesterol and a high incidence of coronary artery disease. Our aims were to track the low density lipoprotein receptor (LDLR) gene in individual families with phenotypic FH and to identify and characterise any mutations of the LDLR gene that may be common in the west of Scotland FH population using single strand conformational polymorphism analysis (SSCP). Patient samples consisted of 80 heterozygous probands with FH, 200 subjects who were related to the probands, and a further 50 normal, unrelated control subjects. Tracking of the LDLR gene was accomplished by amplification of a 19 allele tetranucleotide microsatellite that is tightly linked to the LDLR gene locus. Primers specific for exon 4 of the LDLR gene were used to amplify genomic DNA and used for SSCP analysis. Any PCR products with different migration patterns as assessed by SSCP were then sequenced directly. In addition to identifying probands with a common mutation, family members were screened using a forced restriction site assay and analysed using microplate array diagonal gel electrophoresis (MADGE). Microsatellite D19S394 analysis was informative in 20 of 23 families studied. In these families there was no inconsistency with segregation of the FH phenotype with the LDLR locus. Of the FH probands, 15/80 had a mutant allele as assessed by SSCP using three pairs of primers covering the whole of exon 4 of the LDLR gene. Direct DNA sequencing showed that 7/15 of the probands had a C163Y mutation. Using a PCR induced restriction site assay for the enzyme RsaI and MADGE, it was determined that the C163Y mutation cosegregated with the FH phenotype in family members of the FH probands. This mutant allele was not present in any of the control subjects. Microsatellite analysis has proven useful in tracking the LDLR gene and could be used in conjunction with LDL cholesterol levels to diagnose FH, especially in children and young adults where phenotypic diagnosis can be difficult.

Effect of silica on phospholipase D activity in rat alveolar macrophages

Silica may act as a stimulator of pulmonary inflammation and fibrosis. The effect of silica on phospholipase D (PLD) activity assayed as accumulation of [3H]phosphatidylethanol ([3H]PtdEt) was examined in [3H]palmitic acid-labeled primary cultures of rat alveolar macrophages. Silica induced a rapid accumulation of [3H]PtdEt in a time (0, 15, 30 and 45 min)- and concentration (0.5, 1.0, 2.5 and 5.0 mg/ml)-dependent manner indicating PLD activation. This silica-stimulated PLD activity was attenuated by the pretreatment with calcium chelator ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) or/and 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid acetoxymethyl ester (BAPTA/AM) (EGTA: 54.3 +/- 8.6%, BAPTA/AM: 67.5 +/- 7.8% and EGTA + BAPTA/AM: 35.8 +/- 2.9, respectively). Also, silica-induced PLD activation was partially inhibited by the pretreatment with nonspecific phospholipase C (PLC) and PLD inhibitor (neomycin; 66.4 +/- 4.8%) or specific PLC inhibitor (U73122; 70.8 +/- 4.6%). Sphingosine as a protein kinase C (PKC) inhibitor did not change silica-induced PLD activity indicating that PKC might not play a role in PLD activation by silica. Based on these results, we concluded that a silica-stimulated phospholipase D activity is present in the rat alveolar macrophages and is predominantly regulated by PLC-mediated intracellular calcium.