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PubMed2003

[Prevalence of hepatic involvement, alcoholism, hepatis B, C and HIV in patients with background history of drug use].

UNLABELLED: Drug addicts frequently have liver diseases for different reasons: alcohol abuse, the drugs themselves, but more often hepatitis B and C infections. AIDS is common in this population as well and could also affect the liver directly or in the form of hepatocellular or biliary damage. We conducted this study to determine the prevalence of liver diseases, alcoholism, hepatitis B and C infections, and HIV positivity in this population. We studied a cohort of 137 persons, all with a history of drug abuse, and investigated the quantity of alcohol intake, the kind of drug used, and he routes of drug administration. RESULTS: We found liver disease in 33.6%. The prevalence of alcoholism was 65.4%, of HCV 67.3%, and of HBV 17.3%. HDV was undetectable, whereas we found HIV at a frequency of 17.3%. HCV RNA was detected in 85.4% of HCV. The drug most often used was cocaine at 90.4%, followed by marihuana at 88.3%; LSD use occurred in 17.5%. We found parenteral drug use in 43.1%. We performed 22 liver biopsies, 21 associated with HCV, and detected histological changes consistent with chronic hepatitis in 17, with cirrhosis in 4, and with hepatocellularcarcinoma in 1.

Adolescent↗
PubMed2006

Cloning and expression of manganese superoxide dismutase of the silkworm, Bombyx mori by Bac-to-Bac/BmNPV Baculovirus expression system.

Superoxide dismutase (SODs) are metalloenzymes that catalyze the dismutation of the superoxide anion to molecular oxygen and hydrogen peroxide and, thus, form a crucial part of the cellular antioxidant defense mechanism. In this paper, we used the total fat body RNA of silkworm, Bombyx mori L. to clone and sequence a 648-bp Mn-SOD cDNA fragment through RT-PCR. Furthermore, a newly established Bac-to-Bac/BmNPV Baculovirus expression system was used to overexpress the recombinant Mn-SOD enzyme in silkworm larvae. The hemolymph was collected from the infected larvae 96 h post-infection and subjected to a 12 % SDS-PAGE and Western blotting. A 18.0-kDa protein was visualized after rBacmid/BmNPV/SOD infection. The SOD enzyme activity was determined with a tetrazolium salt for detection of superoxide radicals generated by xanthine and xanthine oxidase and its peak appeared in 96 h post-infection with 2.7 times of the control larvae. The availability of large quantities of SOD that the silkworm provides should greatly facilitate the future research and testing of this protein for potential application in medicine.

Animals↗
PubMed2003

Quantitative, multiplexed detection of bacterial pathogens: DNA and protein applications of the Luminex LabMAP system.

Escherichia coli, Salmonella, Listeria monocytogenes and Campylobacter jejuni are bacterial pathogens commonly implicated in foodborne illnesses. Generally used detection methods (i.e., culture, biochemical testing, ELISA and nucleic acid amplification) can be laborious, time-consuming and require multiple tests to detect all of the pathogens. Our objective was to develop rapid assays to simultaneously detect these four organisms through the presence of antigen or DNA using the Luminex LabMAP system. For nucleic acid detection, organism-specific capture probes corresponding to the 23S ribosomal RNA gene (rrl) were coupled covalently to LabMAP microspheres. Target molecules included synthetic complementary oligonucleotides and genomic DNA isolated from ATCC type strains or other well-characterized strains of each organism. Universal PCR primers were designed to amplify variable regions of bacterial 23S ribosomal DNA, yielding biotinylated amplicons of 86 to 109 bp in length. Varying quantities of targets were hybridized to the combined microsphere sets, labeled with streptavidin-R-phycoerythrin and analyzed on the Luminex(100) system. Results of nucleic acid detection assays, obtained in 30 to 40 min following amplification, correctly and specifically identified each bacterial species with a detection sensitivity of 10(3) to 10(5) genome copies. Capture-sandwich immunoassays were developed with organism-specific antibodies coupled to different microsphere sets. Microspheres were incubated with organism-specific standards and reactivity was assessed with biotinylated detection antibodies and streptavidin-R-phycoerythrin. In the immunoassays, microsphere-associated fluorescence was organism concentration dependent with detectable response at < or = 1000 organisms/ml and with no apparent cross-reactivity. We have demonstrated that the Luminex LabMAP system is a rapid, flexible platform capable of simultaneous, sensitive and specific detection of pathogens. The practical significance of this multiplexing approach would be to provide more timely, economical and comprehensive information than is available with conventional isolation and identification methodologies.

Antigens, Bacterial↗
PubMed1993

Distribution of [125I]nerve growth factor in the rat brain following a single intraventricular injection: correlation with the topographical distribution of trkA messenger RNA-expressing cells.

The present study determined the topographical distribution of [125I] nerve growth factor in rat brain at various time points following an intraventricular injection. In addition, we quantified the tissue content of nerve growth factor in various brain tissues following the injection. Autoradiographic analysis of the distribution of [125] nerve growth factor indicated that the neurotrophin is rapidly distributed within the entire ventricular system. However, penetration of nerve growth factor into the brain parenchyma was very limited. At early time points following an injection of nerve growth factor, there was an accumulation of label in the immediate vicinity of the lateral ventricle and third ventricle with predominant labeling around the septum, hypothalamus and cerebellum. By 24 h following nerve growth factor administration, there was discreet labeling of the lateral septum, medial septum, diagonal band, hypothalamus, olfactory tubercle and nucleus of the olfactory tract, and some label was present in the hippocampus and subiculum. Quantitative ELISA of nerve growth factor in brain tissues 1 h following the injection indicated a 446% and 133% increase over basal levels of nerve growth factor in the basal forebrain and hippocampus, respectively. At 24 h nerve growth factor levels measured in brain were not significantly different from endogenous basal levels as determined by ELISA, whereas there were high quantities of 125I present in the thyroid gland, suggesting that the administered [125I] nerve growth factor was rapidly degraded following the intraventricular injection. We observed a similar labeling pattern of the medial septum/diagonal band cholinergic cell body group 24 h following either an intraventricular or intrahippocampal injection of [125I] nerve growth factor. There was a good correlation between the [125I] nerve growth factor labeling pattern and the presence of trkA messenger RNA. This suggested that, at least in the septohippocampal pathway, nerve growth factor accumulated in a region which contained trkA nerve growth factor receptors. Thus, this study shows that after a single unilateral intraventricular injection of nerve growth factor into rat brain there is effective uptake by diagonal band/septal cells on both sides of the brain, and by cells whose positions correlate with the locations of cholinergic and trk A messenger RNA-expressing cells. Significant uptake was also observed in the hypothalamus and cerebellum. The very limited penetration and rapid degradation of intraventricularly administered nerve growth factor suggests that tissue penetration may be a limiting factor when attempting to influence brain neurons by exogenous neurotropic factors.

Animals↗
PubMed2001

Expression of MRE11 complex (MRE11, RAD50, NBS1) and hRap1 and its relation with telomere regulation, telomerase activity in human gastric carcinomas.

The MRE11 complex (MRE11, RAD50, NBS1) are required for the repair of DNA double-strand breaks and have another important function in regulating telomere length. The silent information regulator (Sir) proteins required for telomere position effect also bind telomeres. hRap1 protein is a human ortholog of yeast Rap1 which regulates telomere length by interacting with TRF2 and is recruited to telomeres by TRF2. We examined the expression of the MRE11 complex (MRE11, RAD50, NBS1), Sir2 and hRAP1 in 20 gastric carcinomas by reverse transcription polymerase chain reaction and then analyzed the relation between telomerase activity and other telomerase components such as human telomerase reverse transcriptase (TERT), human telomerase RNA component (hTR), human telomerase-associated protein (TEP1), telomeric repeat binding factor 1 (TRF1), TRF2- and TRF1-interacting, ankyrin-related ADP-ribose polymerase (tankyrase) as well as TRF1-interacting nuclear protein 2 (TIN2). Of twenty gastric carcinomas examined, 13 (65%), 14 (70%), 16 (80%), 12 (60%) and 13 (65%) expressed MRE11, RAD50, NBS1, Sir2 and hRap1 at higher levels than corresponding nonneoplastic gastric mucosa, respectively. No obvious correlation was observed between MRE11 complex expression and telomerase activity or expression of TERT, hTR, TEP1, tankyrase and TIN2. Carcinomas with high TRF1 expression expressed significantly higher levels of MRE11 and RAD50 than those with low TRF1 expression (p < 0.05). On the other hand, carcinomas with high TRF2 expression expressed significantly higher levels of MRE11, NBS1 and hRap1 than those with low TRF2 expression (p < 0.05). These results suggest that gastric carcinomas with high TRF1 and TRF2 expression may need a large quantity of the MRE11 complex. Moreover, gastric carcinomas with high TRF1 expression may require a large quantity of hRap1.

Aged↗
PubMedDate not supplied

[Changes of humoral and cellular immunity in chronic hepatitis C patients of different staging].

The purpose of the present study was to investigate the influence produced by viral proteins in the hepatic cells and RNA of hepatitis C virus (HCV) on the indices of T- and B-cell response in 52 patients with chronic hepatitis C (CHC). A relative count of peripheral-blood lymphocytes (PBL), expressing antigens CD3+, CD4+, CD8+, CD16+, CD20+ and CD95+ was estimated. The repertoire of antibodies to HCV proteins was specified. The thus obtained data were compared with an activity and a disease stage by using the histological diagnosis and alanine-amino-transferase (ALT) level as well as with the presence of HCV RNA in the serum and viral protein of the liver. Such comparison of data and the use of the correlation analysis made it possible to establish that the antibodies to NS5 protein were detected reliably more often in patients with a more pronounced hepatic fibrosis, with a higher ALT activity and with expression of HCV proteins in the liver. At the same time, the presence of proteins in the liver and of RNA in the serum were accompanied by a more active humoral response to the non-structure proteins of NS4 and NS5 as well as by more profound discrepancies of the immunity T-cell chain (a lowered ratio of CD4+/CD8+ and a smaller content of CD95+). There were no differences between PBL of the studied populations in patients with various activities and an HCV stage. A relatively bigger quantity of CD95(+)--positive PBL was found to be reliably higher in patients with viremia but lower in those cases, in which HCV proteins were detected in the liver. This confirms the inhibiting ability of HCV proteins to the Fas-mediated apoptose of PBL in CHC patient.

Adolescent↗
PubMed2004

Epithelial cell preparation for proteomic and transcriptomic analysis in human pancreatic tissue.

Standardized sample preparation procedures constitute a prerequisite for obtaining reliable and reproducible results in gene expression research in humans. In particular, in diseases such as pancreatic cancer and pancreatitis, isolating epithelial cells is an important step preceding such research. In pancreatic tissue, the high amount of RNAases is a further problem when it comes to obtaining high-quality RNA, and the presence of secreted proteases accelerates protein degradation. We developed a successful method that addresses these different problems. This method, which uses epithelial cell surface antibody Ber-Ep4, proteases, and RNAases inhibitors, leads to a significant enrichment (> 95% purity) of epithelial cells from fresh human tissue samples and allows for both proteomics (Western Blot, 2D PAGE) and transcriptomics studies (rtPCR, cDNA microarray). Compared with other cell purification procedures, this method is characterized by several advantages: a large quantity of cells available for downstream analysis, combined transcriptomics and proteomics studies using the same samples, better reproducibility of proteomics studies, and an acceptable yield (63%) for gene expression arrays studies. Moreover, a quality control protocol addressing the needs of the industry and the requirements of regulatory agencies is proposed.

Epithelial Cells↗
PubMed1993

RNA multi-structure landscapes. A study based on temperature dependent partition functions.

Statistical properties of RNA folding landscapes obtained by the partition function algorithm (McCaskill 1990) are investigated in detail. The pair correlation of free energies as a function of the Hamming distance is used as a measure for the ruggedness of the landscape. The calculation of the partition function contains information about the entire ensemble of secondary structures as a function of temperature and opens the door to all quantities of thermodynamic interest, in contrast with the conventional minimal free energy approach. A metric distance of structure ensembles is introduced and pair correlations at the level of the structures themselves are computed. Just as with landscapes based on most stable secondary structure prediction, the landscapes defined on the full biophysical GCAU alphabet are much smoother than the landscapes restricted to pure GC sequences and the correlation lengths are almost constant fractions of the chain lengths. Correlation functions for multi-structure landscape exhibit an increased correlation length, especially near the melting temperature. However, the main effect on evolution is rather an effective increase in sampling for finite populations where each sequence explores multiple structures.

Base Composition↗
PubMed1990

Polymerase chain reaction amplification and typing of rotavirus nucleic acid from stool specimens.

The rotavirus gene segment coding for the major outer capsid glycoprotein vp7 was amplified directly from stool specimens by the polymerase chain reaction (PCR). Double-stranded RNA extracted from stool samples was used as the template for reverse transcription, which was followed immediately and in the same reaction mix with amplification, using the Taq polymerase. Various conditions were examined to optimize the yield of the amplified gene. The concentrations of MgCl2, dimethyl sulfoxide, and template RNA were critical. The choice of primer pairs allowed amplification of the entire segment or specific portions. By using type-specific primers derived from distinct regions on the gene, we devised a PCR typing method in which each human serotype virus produced a characteristic segment size, readily identifiable in agarose gels. The PCR typing method was applied to 10 rotavirus reference strains, including all 6 known human serotypes (serotypes 1, 2, 3, 4, 8, and 9), and to 34 stool specimens previously serotyped by an enzyme immunoassay with monoclonal antibodies. An absolute correlation was found between the molecular and serologic methods. In addition, 14 stool specimens nonserotypable by an enzyme immunoassay with monoclonal antibodies could be typed by the PCR method. Besides the application for rotavirus detection and typing directly from stools, the PCR method provides a rapid and efficient means of obtaining large quantities of cDNA suitable for sequencing, cloning, and other genetic studies, precluding the need for cell culture and virus purification.

Base Sequence↗
PubMed1999

Somatic growth and clinical manifestation in formula fed infants born to HIV--infected mothers during the first year of life.

This was a comparative study of the growth and clinical manifestation between infected and uninfected HIV infants both of whom were fed with a limited quantity of powder milk from birth until one year of age. HIV-infected pregnant women were enrolled from the second trimester or the beginning of the third trimester. After birth, infants had physical examinations, body weight and height were recorded at 2, 4, 6, 9 and 12 month visits. All mothers were given 7 kilograms of infant formula at each infant visit until the infant was one year old. Diagnosis for HIV infection in these infants was made by two positive concordant results of DNA PCR or RNA PCR or HIV RNA. One hundred and two infants were diagnosed for HIV status and 21.5 per cent were infected. The infected infants showed signs of malnutrition. From 2-4 months of age, the averages of their weights and heights were lower than those of non-infected infants. Abnormal clinical signs were found in most infected infants by the time they were 9-12 months old. In conclusion for the infants born to HIV- infected mothers, monitoring signs and symptoms including their weight and height from birth till 9-12 months old, is predictive of the infectious status of most infected infants. The administration and management of infant formula in a limited quantity to HIV infected mothers in upper northern provinces of Thailand is possible without causing abnormal infant growth.

Female↗
PubMed1995

Molecular characterization of a testis-specific estrogen sulfotransferase and aberrant liver expression in obese and diabetogenic C57BL/KsJ-db/db mice.

Sulfation represents a major pathway for the inactivation of steroid hormones such as estrogens and is catalyzed by a group of enzymes called sulfotransferases. Aberrant regulation of an estrogen sulfotransferase has been demonstrated previously in the livers of obese and diabetogenic C57BL/KsJ-db/db strain mice. In this paper, we report the molecular cloning and functional characterization of a full-length complementary DNA for estrogen sulfotransferase from mouse testis. The mouse estrogen sulfotransferase complementary DNA encodes 295 amino acids. It shares 88%, 77%, 75%, and 68% identity in amino acid sequence with the rat liver, human liver, guinea pig adrenal, and bovine placental estrogen sulfotransferase, respectively. The mouse enzyme was expressed as a glutathione-S-transferase fusion protein in Escherichia coli. The fusion protein was affinity purified, and milligram quantities of pure enzyme were obtained after cleavage of the fusion protein with thrombin. The expressed enzyme exhibits a high substrate specificity toward estrogens, including estradiol and estrone. Neither dehydroepiandrosterone, pregnenolone, testosterone, nor a simple phenolic compound, 4-nitrophenol appears to be a substrate. Northern hybridization indicates that messenger RNA (1.3 kilobases) for the estrogen sulfotransferase is expressed exclusively in the testes in control C57BL/KsJ mice. However, both the messenger RNA and protein are dramatically induced in the livers of obese and diabetogenic C57BL/KsJ-db/db mice. In contrast to the liver, the constitutive expression of the enzyme in the testis is not affected by the db/db genotype. These results recapitulate the species-specific nature in the tissue distribution of estrogen sulfotransferase and suggest complex regulatory mechanisms in its expression under normal and pathophysiological conditions.

Amino Acid Sequence↗
PubMed2003

[Quantitative analysis of expression of TEY1 gene in liver cancer cells with different metastatic potential].

BACKGROUND & OBJECTIVE: The authors' previous study suggested there could be metastasis suppressor gene for liver cancer on human chromosome 8p. TEY1 was a newly discovered metastasis suppressor gene for prostate cancer located on human chromosome 8p. In order to explore whether TEY1 gene could be a metastasis suppressor gene for liver cancer, the expression of TEY1 was quantitated in liver cancer cell strains with different metastatic potential. METHODS: RNA was extracted from liver cancer cell strains, MHCC97-H, MHCC97-L, and HCCLM3, and normal liver cell line L02. The first strand cDNA was synthesized by reverse transcription, which was then used as the template to perform fluorescent quantitative polymerase chain reaction (FQ-PCR). The quantity of the expression of TEY1 gene was normalized by dividing with that of the housekeeping gene, GAPDH for each sample. One-way analysis of variance (ANOVA) was performed for the normalized values. RESULTS: The normalized initial cDNA concentrations of TEY1 in MHCC97-H, MHCC97-L, HCCLM3, and L02 were (3.57+/-2.62) x 10(-4), (5.02+/-1.95) x 10(-4), (2.82+/-0.78) x 10(-5), and (15.20+/-0.58) x 10(-4), respectively. The expression level of TEY1 in L02 was significantly different from those of liver cancer strains (P< 0.001). The expression level of TEY1 in HCCLM3 was also significantly different from those in MHCC97-H and MHCC97-L (P< 0.05). But there was no significant difference between MHCC97-H and MHCC97-L although the expression level of TEY1 gene in MHCC97-L was 1.4 times higher than that in MHCC97-H. CONCLUSION: The expression levels of TEY1 gene in liver cancer cells were negatively correlated with their different metastatic potentials; it could be conjectured that TEY1 may possibly be a metastasis suppressor gene for liver cancer.

Cell Line, Tumor↗
PubMed1986

Dexamethasone differentially affects the levels of calcitonin and calcitonin gene-related peptide mRNAs expressed in a human medullary thyroid carcinoma cell line.

The TT cells are a continuous line of human C-cells derived from a medullary thyroid carcinoma. These cells produce large quantities of calcitonin and calcitonin gene-related peptide (CGRP) by the differential splicing of a single calcitonin gene transcript. We have used specific cDNA probes for calcitonin and CGRP to study the regulation of the calcitonin gene by dexamethasone, a synthetic glucocorticoid. Northern blot analysis of total cellular RNA isolated from the TT cells showed hybridization of the calcitonin probe to 3600- and 1000-base RNA species. The CGRP probe hybridized to 3600- and 1050-base RNA species. Dexamethasone treatment (10(-9) to 10(-5) M) of TT cells (for 6 days) caused a dosage-dependent increase in calcitonin mRNA levels and a decrease in CGRP mRNA levels. These findings were confirmed in time course studies where dexamethasone treatment (10(-6) M) caused a 2-13-fold increase in calcitonin mRNA and a 40-60% decrease in CGRP mRNA between 4 and 6 days of treatment; the effect was reversible after dexamethasone withdrawal. After excluding an effect of dexamethasone on calcitonin and CGRP mRNA stability, we have concluded that dexamethasone affects the splicing mechanism to favor production of calcitonin mRNA over CGRP mRNA.

Calcitonin↗
PubMed1981

The eucaryotic cell-lipochromosome as a new host-vector system in gene amplification and expression.

Although procaryotes such as E. Coli are generally considered to be ideal hosts, able to amplify eucaryotic gene sequences contained within hybrid DNA plasmid molecules (3, 14), recent experimental evidence such as the decreased bacterial viability observed during the cloning of mouse mitochondrial DNA, clearly shows the limitations of this type of approach (6). In addition, major technical difficulties are encountered during the isolation and purification of the specific messenger RNA (mRNA) needed to synthetize the complementary DNA (cDNA) molecule (1, 4). Last but not least, after having screened many different bacterial clones -- provided that the foreign gene product is not toxic for its host -- it is still a question of good luck to get one clone producing adequate quantities of the biologically active protein of interest, free of contaminants. On the other hand, the low but significant frequency with which eucaryotic cells exposed to fragmented DNA molecules or metaphasic chromosomes phenotypically express a particular marker suggests that this approach might offer an alternative to the bacteria-plasmid system used in "classic" genetic engineering (10, 17, 18, 19). It is the purpose of this work to briefly discuss some of the difficulties involved in this approach and to propose solutions.

Chromosomes↗
PubMed2005

Dehydroascorbate transport in human chondrocytes is regulated by hypoxia and is a physiologically relevant source of ascorbic acid in the joint.

OBJECTIVE: To evaluate the dehydroascorbate (DHA) transport mechanisms in human chondrocytes. METHODS: The transport of L-(14)C-DHA in human chondrocytes was analyzed under various conditions, including the use of RNA interference (RNAi), to determine the role of glucose transporter 1 (GLUT-1) and GLUT-3 in L-14C-DHA transport and to evaluate the effects of physiologically relevant oxygen tensions on L-14C-DHA transport. In order to estimate the contributions of reduced ascorbic acid (AA) and DHA to intracellular ascorbic acid (Asc), the quantities of AA and DHA were measured in synovial fluid samples from osteoarthritis (OA) patients and compared with the reported levels in rheumatoid arthritis (RA) patients. RESULTS: DHA transport in human chondrocytes was glucose-sensitive, temperature-dependent, cytochalasin B-inhibitable, modestly stereoselective for L-DHA, and up-regulated by low oxygen tension. Based on the RNAi results, GLUT-1 mediated, at least in part, the uptake of DHA, whereas GLUT-3 had a minimal effect on DHA transport. DHA constituted a mean 8% of the total Asc in the synovial fluid of OA joints, in contrast to 80% of the reported total Asc in RA joints. CONCLUSION: We provide the first evidence that chondrocytes transport DHA via the GLUTs and that this transport mechanism is modestly selective for L-DHA. In the setting of up-regulated DHA transport at low oxygen tensions, DHA would contribute 26% of the total intracellular Asc in OA chondrocytes and 94% of that in RA chondrocytes. These results demonstrate that DHA is a physiologically relevant source of Asc for chondrocytes, particularly in the setting of an inflammatory arthritis, such as RA.

Arthritis, Rheumatoid↗
PubMed1996

Changes in poly(A) tail length of arginine vasotocin messenger ribonucleic acid in the hypothalamus of water-deprived chickens.

The effects of water deprivation on the secretion of vasotocin (AVT) and expression of the AVT gene were studied in White Leghorn cockerels. Animals deprived of water for 4 days were compared with normally hydrated controls. Blood samples were obtained for measurements of plasma osmolality and AVT levels, and the hypothalamus was collected for extraction of total cellular RNA. A 519-bp AVT cDNA was prepared by reverse transcriptase-polymerase chain reaction and a 209-bp PstI/EcoRI restriction fragment from the 3' region of the fowl AVT cDNA was used as a probe for Northern blot analysis. Plasma osmolality and AVT levels in dehydrated birds were about 30 and 350% greater, respectively, than those in normally hydrated controls. The quantity of hypothalamic AVT mRNA was 2. 3-fold greater in water-deprived birds compared to controls. The size of the hypothalamic AVT transcript was about 100-bp longer in the water-deprived birds. As determined by RNase H treatment in the presence and absence of oligo(dT)12-18, the increase in mean size of the AVT mRNA in dehydrated animals was due to a longer poly(A) tract. Our results indicate that osmotic stress up-regulates expression of the AVT gene and increases the accumulation of AVT mRNA in the hypothalamus. This accumulation may, in part, be due to lengthening of the AVT mRNA poly(A) tail which is a general mechanism associated with stabilization of vertebrate mRNAs.

Animals↗
PubMed1981

Detection of alpha-amylase activity in unprocessed preamylase produced in the cell-free translation of porcine pancreatic RNA.

Preamylases, synthesized in the RNA-dependent rabbit reticulocyte lysate translation system supplemented with porcine pancreatic RNA were identified by their specific immunoprecipitation with anti-amylase. The preamylases have apparent Mr = 55,000 and 58,000 as compared to 52,000 and 55,000 for the purified, secreted alpha-amylase isozymes. In order to establish whether the unprocessed precursors may assume enzymatically active conformations, we have explored a highly sensitive activity gel electrophoresis technique, by which picogram quantities of enzyme can be detected. When standard alpha-amylase and translation products are subjected to electrophoresis on polyacrylamide gel containing 0.01% starch and CaCl2, active amylase which binds tightly to starch can only migrate as the starch is hydrolyzed. When the gel is subsequently stained with I2, the appearance of clear tracks, the lengths of which are roughly proportional to the logarithm of amylase concentration, signifies the presence of amylase activity. By this approach, we were able to detect amylase activity in a range corresponding to about 100 pg of pure amylase/10 microliters of translation mixture. This value agrees well with an estimate from radioactivity incorporation of total preamylase in the translation mixture, and we consequently conclude that unprocessed preamylase can assume the appropriate conformation to give enzymatic activity.

Amylases↗