GC-MS fingerprint of Pogostemon cablin in China

Pogostemon cablin, originating in Malaysia and India, is cultivated in southern China including Guangdong and Hainan Province, which was called GuangHuoXiang to differentiate it from the HuoXiang of the north, the species Agastache rugosa, that it resembles. Essential oil of P. cablin mainly contributes to the pharmacological activities and the therapeutic properties of the essential oils are directly correlated with their qualitative and quantitative composition. For controlling the quality, standard fingerprint of P. cablin collected from different regions was developed by using GC-MS. Nine compounds including beta-patchoulene, caryophyllene, alpha-guaiene, seychellene, beta-guaiene, delta-guaiene, spathulenol, patchouli alcohol and pogostone were identified among 10 main peaks in P. cablin. Hierarchical clustering analysis based on characteristics of 10 investigated peaks in GC profiles showed that 18 samples were divided into three main clusters, patchouliol-type, pogostone-type and an interim-type, which was the one between the two chemotypes. The simulative mean chromatogram for the three types P. cablin was generated using the Computer Aided Similarity Evaluation System. The fingerprint can help to distinguish the substitute or adulterant, and further assess the differences of P. cablin grown in various areas of China.

Analysis of factors affecting the epidemiology of tuberculosis in China

SETTING

The tuberculosis (TB) epidemic situation is both a public health problem and a socio-economic issue in China.

OBJECTIVE

To examine the effects of socio-economic development and of the TB control strategy on the TB epidemic in China.

METHODS

Based on the four National Epidemiological Surveys of TB and the indices of socio-economic development in China, correlation co-efficiency was used to analyse the relationship between changes in the TB epidemic situation, the socio-economic level and the Health V TB control Project.

RESULTS

The prevalence of smear-positive TB had significant medium correlation with the per capita net income of the rural population, the consumption level of the urban population, the per capita GDP, the population density, and the proportion of rural to total population, among which the correlation with the first four was negative and with the last was positive. The decline in prevalence in the project areas was much greater than in the non-project areas (44.4% vs. 12.3%), while their GDP increases were similar.

CONCLUSION

With socio-economic development, correlation between the socio-economic indices and the TB epidemic becomes more significant. The TB control project is vital to reduce the prevalence of TB in China.

Expression of survivin and bax/bcl-2 in peroxisome proliferator activated receptor-gamma ligands induces apoptosis on human myeloid leukemia cells in vitro

The present study was undertaken to investigate the mechanisms of peroxisome proliferator activated receptor-gamma (PPAR-gamma) ligand-induced apoptosis on human myeloid leukemia K562 and HL-60 cell lines. The results revealed that both 15-deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2) and troglitazone (TGZ) have significant anti-proliferation- and apoptosis-inducing effects on these two kinds of leukemia cells. Marked morphological changes of cell apoptosis including condensation of chromatin and nuclear fragmentation were observed clearly using Wright's and Hoechst 33258 staining. Reverse transcription-PCR and western blot analyses demonstrated that both survivin and bcl-2 expression were downregulated markedly, while bax expression was upregulated concurrently when apoptosis occurred. We therefore conclude that 15d-PGJ2 and TGZ have significant apoptosis effects on K562 and HL-60 cells in vitro, and that upregulation of bax as well as downregulation of survivin and bcl-2 expression may be the important apoptosis-inducing mechanisms. The results suggest that PPAR-gamma ligands may serve as potential therapeutic agents for both acute and chronic myeloid leukemia.

Oridonin-induced apoptosis in leukemia K562 cells and its mechanism

Oridonin, an extract from the Chinese herb Rabdosia rubescens, is currently one of the most important traditional Chinese herbal medicines. Recently oridonin has been reported to have anti- tumor effects in a large variety of malignant diseases. In this study, we investigated the apoptotic inducing effect of oridonin in leukemia K562 cells and its mechanism. Cell growth inhibition was measured using a microculture tetrazolium assay, apoptosis was measured by flow cytometry and electron microscopy as well as by DNA fragmentation analysis. Telomerase activity was measured by TRAP-enzyme- linked immunosorbent assay, and the expression of Bcl-2 and Bax proteins was detected by western blot analysis. The results showed that oridonin could inhibit the proliferation and induce apoptosis on leukemia K562 cells remarkably. Telomerase activity as well as Bcl-2 expression was down- regulated, while Bax expression was up-regulated concurrently, when apoptosis ocurred. We therefore conclude that oridonin demonstrated anti-proliferative and apoptosis-inducing effects on K562 cells in vitro, and that changes in bcl-2 and bax protein levels as well as telomerase activity may play an important role in its mechanism of action.

Simultaneous determination of six main nucleosides and bases in natural and cultured Cordyceps by capillary electrophoresis

A simple method is described for simultaneous determination of six main nucleosides and bases including adenine, uracil, adenosine, guanosine, uridine and inosine in Cordyceps by capillary electrophoresis (CE). Chemometric optimization based on central composite design was employed to find the optimum resolution. The optimum factor space was defined by three parameters: buffer concentration, pH and concentration of acetonitrile as organic modifier. Resolution (Rs) was employed to evaluate the response function. A running buffer composed of 500 mM boric acid, adjusted pH to 8.6 with sodium hydroxide and 12.2% acetonitrile as modifier was found to be the most appropriate for the separation. The contents of the six components were determined by using adenosine monophosphate as an internal standard. Furthermore, hierarchical clustering analysis based on characteristics of 32 peaks in CE profiles from the tested 12 samples showed that natural and cultured Cordyceps were in different clusters. Adenosine and inosine were extracted as markers for discrimination of natural Cordyceps. The result of clustering based on the two peaks characteristics was in excellent agreement with that based on 32 peaks'. Thus, adenosine and inosine could be used as markers for quality control of natural and cultured Cordyceps.

Anti-proliferative Effects of Oridonin on SPC-A-1 Cells and its Mechanism of Action

Oridonin, an extract from the Chinese herb Rabdosia rubescens, is currently one of the most important traditional Chinese herbal medicines. We investigated the anti-proliferative effect of oridonin on the lung cancer cell line SPC-A-1 and its mechanism of action. Growth inhibition was measured using a microculture tetrazolium assay and apoptosis was measured by several standard methods. Western blot analysis measured the expression of bcl-2 and bax proteins. Oridonin (> 28 μmol/l) inhibited the growth of SPC-A-1 cells and induced apoptosis. Marked morphological changes indicative of apoptosis were observed, especially in cells treated with oridonin for 48–60 h. Western blot analysis revealed downregulation of bcl-2 and upregulation of bax proteins following treatment with oridonin for 48 h. We conclude that oridonin demonstrated anti-proliferative and apoptosis-inducing effects on SPC-A-1 cells in vitro, and that changes in bcl-2 and bax protein levels may play an important role in its mechanism of action.

Endoluminal gastroplication for treatment of patients with classic gastroesophageal reflux symptoms and borderline 24-h pH studies

BACKGROUND

Patients with classic gastroesophageal reflux disease (GERD) symptoms and borderline 24-h pH studies are not considered to be good candidates for surgical fundoplication. Endoluminal gastroplication (ELGP) is a new endoscopic treatment for patients with GERD. The aim of this study was to evaluate the efficacy of ELGP in these patients.

METHODS

Patients with heartburn, regurgitation symptoms and a DeMeester score of less than 30 were studied. ELGP involved placement of two or three plications within 2 cm of the gastroesophageal junction. Clinical outcomes measured were heartburn symptom score (HSS), regurgitation frequency score (RFS) and medication use.

RESULTS

Twenty-five patients (11 M, 14 F, mean age of 51 years) had a medication use of 11.5 doses of proton-pump inhibitors per week prior to ELGP. Average lower esophageal sphincter pressure measured 15 +/- 8 mmHg, and average DeMeester score was 18 +/- 8. Nine patients had hiatal hernias and 11 had esophagitis. Twenty-four patients were available for a mean follow-up of 12 months. HSS significantly decreased from 48 to 17 (P < 0.01) and RFS was reduced from 1.8 to 0.7 (P < 0.01). Proton-pump inhibitor use was 5.3 doses per week (P < 0.01) post-ELGP; 12 patients (50%) were off medications, 3 (13%) had a 50% reduction in medication use, and in 9 (37%) there was no change. Complications were bleeding in one patient and aspiration pneumonia in another patient.

CONCLUSIONS

Endoluminal gastroplication provides symptomatic relief for patients with classic GERD symptoms despite medical therapy and borderline 24-h pH studies.

Cloning and sequencing of complete cDNA of Japanese encephalitis virus YL strain in Taiwan

We determined the complete nucleotide sequence of the YL strain of Japanese encephalitis virus and its amino acid sequence was deduced. Our results displayed that the genome of YL strain contained a single open reading frame of 10,296 nucleotides (nts) which was flanked by untranslated region (UTR) containing 95 bases at the 5'-end and 586 bases at the 3'-end, respectively. Comparison of sequences showed that the overall amino acid sequence and 3' UTR of YL were similar to those of the virulent strain JaGAr0l. However, some significant amino acid differences of viral envelope (E) protein were observed between YL and JaGAr01; the amino acid sequence of E protein in YL strain possessed RGG(387-389) tripeptide instead of RGD(387-389) in JaGAr01 and in other strains; and another amino acid is K(138) in YL, not E(138) found in others. These differences suggested that the YL strain impairs in viral attachment to the cell surface and loses neuroinvasiveness, and therefore this strain was used as a live attenuated vaccine.

A description for computed tomography based on sinusoidal curves

A new description for computed tomography, parallel and equal to Radon transformation but based on sinusoidal functions rather than line integrals, is introduced. This representation contributes an effective algorithm to reduce metal artefacts in reconstruction. Using this method, the information included in the scan data corresponding to the metal implants can be separated from the original projection, an amending method rather than interpolation is therefore provided to reach higher accuracy for reconstruction. The method is with low complexity in computation, and can be combined online with filtered backprojection (FBP), which is the most widely used algorithm in practice, to improve the quality of the reconstructed image. Also, the method has the potential to deal with the artefacts caused by beam hardening and partial volume, and to be developed into a straight reconstruction algorithm based on the sinusoidal representation. Examples are presented for clearer description and demonstration.

Cloning and sequencing of full-length cDNA of classical swine fever virus LPC strain

The cDNAs of classical swine fever virus (LPC vaccine strain) were cloned by transcriptase-polymerase chain reaction, and their nucleotide sequences were determined. In this work, we obtained the sequence information of the 786 bases of the 5'-terminal region, 6049 bases of the middle region, and 1648 bases of the 3'-terminal region. Taking our previous results and present data together, the entire genomic sequence of LPC strain was completed (12344 nucleotides in length). The genome of LPC has a large open reading frame that can encode a polypetide of 3897 amino acids, and are flanked by untranslated regions (UTR), 373 bases at the 5'-end and 278 bases at the 3'-end. Phylogenetic analysis based on genomic sequences of several viruses suggested that the LPC strain is closer to Chinese, Riems, HCLV, Alfort/187, Brescia, and Alfort strains in order. After further analysis, we found that an insertion of 13 nucleotides, TTT(C/T)CTTTTTTTT, in the 3'-UTR of LPC, Chinese, and HCLV strains. Immediately downstream to the 13 nucleotides, a unique sequence of LPC consisting of 28 thymidine was observed.

[Identification of genes related to cell phenotypic transition by differential display analysis]

To identify the genes that are differentially expressed during the phenotypic transition from vascular adventitial fibroblasts to myofibroblasts, the adventitial fibroblasts were cultured from rat thoracic aorta, and myofibroblasts were obtained by treatment of fibroblasts with TGF-beta1. Differential display PCR (DD-PCR) was used to screen for differentially expressed genes by comparison of mRNA extracted from the two cell populations. Bands upregulated or downregulated on DD gels were excised, reamplified, cloned and sequenced. DD results were verified by quantitative PCR and Northern blot analysis.Antisense oligonucleotide was transfected to study the effect of osteopontin on migration of AF. Differential display showed a significant difference in gene expression profile between the two cell types. A transcript that was downregulated in myofibroblasts showed high DNA sequence homology to part of the gene for NADH dehydrogenase subunit 5. An upregulated transcript showed significant sequence homology to osteopontin gene. Quantitative PCR and Northern blot analysis confirmed the DD results. Among the other differential bands detected, 4 candidate sequences showed no homology to the known genes. The AF numbers of migration were significantly decreased by use of OPN antisense oligonucleotide. This study suggests that the downregulation of gene encoding NADH dehydrogenase subunit 5 and upregulation of osteopontin gene and several other unknown genes may be involved in the phenotypic transition of adventitial fibroblasts to myofibroblats. Inhibition of the expression of OPN may play an important role in the process of vascular remodeling.

Proinflammatory chemokine induction in keratocytes and inflammatory cell infiltration into the cornea

PURPOSE

To determine the effect of interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha on cytokine, chemokine, and receptor expression in corneal stromal cells; the effect of corneal scrape injury on monocyte chemotactic and activating factor (MCAF) expression and monocyte-macrophage influx into the stroma; and the effect of MCAF and granulocyte colony-stimulating factor (G-CSF) microinjection on inflammatory cell infiltration into the stroma.

METHODS

Gene array technology was used to evaluate changes in cytokine, chemokine, and receptor gene expression in stromal fibroblasts in response to IL-1alpha and TNFalpha. Expression of MCAF mRNA and protein was monitored with an RNase protection assay and Western blot analysis, respectively. Keratocyte MCAF protein expression in the rabbit cornea was detected with immunocytochemistry. After epithelial scrape injury, monocytes-macrophages were detected in rabbit corneas, by immunocytochemistry for monocyte-macrophage antigen. Inflammatory cell infiltration after MCAF and G-CSF microinjection into the stroma of mouse corneas was monitored with hematoxylin and eosin staining.

RESULTS

IL-1alpha or TNFalpha upregulated the expression of several proinflammatory chemokines in stromal fibroblasts in culture. These included G-CSF, MCAF, neutrophil-activating peptide (ENA-78), and monocyte-derived neutrophil chemotactic factor (MDNCF). MCAF mRNA upregulation was confirmed by RNase protection assay, and MCAF protein was detected by Western blot analysis. MCAF protein was detected in keratocytes at 4 hours and 24 hours after epithelial injury, but not in keratocytes in the unwounded cornea. Corneal epithelial injury triggered the influx of monocytes-macrophages into the corneal stroma in the rabbit. Microinjection of MCAF and G-CSF into mouse cornea resulted in the influx of monocytes-macrophages and granulocytes, respectively, into the stroma.

CONCLUSIONS

Proinflammatory chemokine induction in keratocytes is mediated by IL-1alpha and TNFalpha. The proinflammatory chemokines produced by the keratocytes probably trigger the influx of inflammatory cells into the stroma after epithelial injury associated with corneal surgery, contact lenses, or trauma.

Characterization of human and mouse angiopoietin-like factor CDT6 promoters

PURPOSE

Angiogenesis refers to the latter stage of vascular development. It has been reported that angiopoietin-like factor cornea-derived transcript 6 (CDT6) encodes a protein homologous to angiopoietins that could play a critical role in blocking a receptor of angiopoietin (Tie2) and therefore contribute to the avascularity and transparency of the cornea in the developing embryo and the adult. This study was focused on isolation and characterization of the CDT6 promoter.

METHODS

Rapid amplification of cDNA ends (5'-RACE) was used to isolate the CDT6 promoter from an adaptor-ligated genomic DNA fragment library and to identify the transcription initiation site of the CDT6 gene. The RNase protection assay was performed to confirm the initiation site. The sequence similarity, binding sites for putative transcription factors, and transcriptional activity of human and mouse CDT6 promoters were compared. Corneal and noncorneal cells from humans and other animals were transiently transfected with CDT6 promoter-chloramphenicol acetyltransferase (CAT) reporter constructs to analyze the transcriptional activity of the promoter.

RESULTS

A 2956-bp human CDT6 promoter fragment and a 3142-bp mouse CDT6 promoter fragment were isolated. The major transcription initiation sites of the human and mouse CDT6 genes were located at 224 and 168 bp, respectively, upstream of the translation initiation site. Human and mouse CDT6 promoter sequences were very similar. Both promoters were minus TATA and CAAT boxes close to the transcription initiation site. Transfection into human corneal and noncorneal cells and into nonhuman cells revealed that the human CDT6 promoter probably contains positive and negative cis-regulatory elements that modulate cell, tissue, and species specificity. The human CDT6 promoter contains four interferon (IFN)-stimulated response elements (ISREs). No ISREs could be identified in the mouse promoter. IFN-alpha stimulated transcriptional activity of the human promoter.

CONCLUSIONS

The human and mouse CDT6 promoters have similar sequences and share many cis-regulatory elements. IFN-alpha appears to have an important role in regulating transcription of the human, but not the mouse, CDT6 promoter.

Differential expression analysis by gene array of cell cycle modulators in human corneal epithelial cells stimulated with epidermal growth factor (EGF), hepatocyte growth factor (HGF), or keratinocyte growth factor (KGF)

PURPOSE

To identify and differentiate cell cycle and differentiation genes that are up-regulated or down-regulated in human corneal epithelial cells in response to alternative epithelium-modulating cytokines epidermal growth factor (EGF), hepatocyte growth factor (HGF) or keratinocyte growth factor (KGF).

METHODS

Primary cultures human corneal epithelial cell (HCE) were treated with 25 ng/ml of EGF, 25 ng/ml HGF, 25 ng/ml KGF, or vehicle for 8 hours. Complementary DNA (cDNA) probes were synthesized from total cellular RNA isolated from the HCE cells. The cDNA probes were hybridized to the Atlas human cell cycle/differentiation array membrane. RNAse protection assay was used to confirm up-regulation of the serine/threonine-protein kinase PITALRE gene by EGF, KGF, and HGF.

RESULTS

The expression of one hundred and eleven cell cycle and differentiation genes was monitored with the gene array system. It was found that these epithelial cell-modulating cytokines shared similar effects on some of the cell cycle and differentiation genes that were monitored, but had specific effects on some cytokines. Up-regulation of PITALRE gene expression was confirmed using RNAse protection assay.

CONCLUSION

EGF, HGF and KGF had differential effects on cell cycle- and differentiation-related gene expression in corneal epithelial cells. For example, all three mitogenic growth factors up-regulated the expression of cyclin D1 (BCL-1 oncogene) and serine/threonine-protein kinase PITALRE in the primary cultured human corneal epithelial cells. However, EGF and KGF, but not HGF, up-regulated expression of the E2F-1 pRB-binding protein gene. Thus, while these three epithelial mitogens have similar effects on many genes that were analyzed, important differences were noted that may relate to differing effects of these growth factors on corneal epithelial cells. Studies to analyze the significance of the identified differences among these growth factors are in progress.

[Research on the selecting suspension cell line of higher productivity of flavonol glycoside by hypoxia stress as well as the stability in subcultures]

Investigate the influence of culture media to growth and flavonol glycoside synthesis of calli introduced from seedling of Ginkgo biloba. 6 cell lines were selected from calli by hypoxia stress. Among these cell lines the best one TZ-1 which growth index was 4.12 and the flavonol glycoside content was 1.25% in dried cell which was enhanced 257.1% compared with callus. The stability in subcultures was investigated: The average content of flavonol glycoside was 1.25% in dried cells and the growth index was 3.99 during 6 subcultures. Which variation coefficient was separately 0.065 and 0.048. The results show that hypoxia stress is a efficient method to select suspension cell line of higher productivity of flavonol glycoside.

Activation of neutral sphingomyelinase participates in ethanol-induced apoptosis in Hep G2 cells

The mechanism underlying ethanol-induced apoptosis in liver cells is not clear. Sphingomyelin (SM) metabolism is a novel signal transduction pathway that has an impact on apoptosis in many cell types. We investigated whether the SM pathway is involved in ethanol-induced apoptosis in the liver. Hep G2 cells were treated with ethanol followed by assaying apoptosis, sphingomyelinase (SMase) activity, caspase-3 activity, and the changes of SM content in the cells. We found that ethanol dose-dependently increased apoptosis and the effect was accompanied by increases of caspase-3 activity and neutral SMase activity. At concentrations of 80 and 160 mM, ethanol significantly increased caspase-3 activity by 120% and neutral SMase activity by 24%. The activity of acid SMase was only slightly increased without statistical significance. C(2)-ceramide, the exogenous SM metabolite, mimicked the effects of ethanol on apoptosis and caspase-3 activation. When the SM content was determined 24 h after treatment with ethanol, its level was 15% lower than that of controls. The results indicate that metabolism of SM triggered by neutral SMase participates in ethanol-induced apoptosis in Hep G2 cells and activation of caspase-3 is involved in the apoptotic pathway.

PCD1, a novel gene containing PDZ and LIM domains, is overexpressed in several human cancers

In an effort to discover novel genes differentially expressed in human pancreatic cancer, we have identified a gene named PCD1 (pancreatic cancer derived) that is up-regulated in pancreatic dysplasia and cancer relative to normal pancreatic ductal epithelium. We cloned the full length (4572 bp) of this gene, which encodes a novel protein of 1064 amino acids containing a PDZ domain and a LIM domain. An alternatively spliced form with a deletion of 30 bp in the coding region was also found. In situ hybridization results showed that PCD1 is highly expressed in a significant percentage of colon, breast, liver, lung, pancreas, stomach, and prostate tumor tissues but is expressed in very few normal tissues. Northern blot hybridization confirmed the overexpression of PCD1 in colon and breast tumor tissues and also showed strong expression of PCD1 in the heart as well as in HeLa cells. Real-time quantitative reverse transcription-PCR verified the overexpression of PCD1 in primary colon tumors or in liver metastases relative to normal colon tissues in five of eight patients. The PCD1 gene maps to human chromosome 13q21.33. Because of its high levels of expression in neoplastic tissues and the presence of both PDZ and LIM domains, we suggest that PCD1 may play an important role in cytoskeletal reorganization during carcinogenesis.

Effects of phospholipids on sphingomyelin hydrolysis induced by intestinal alkaline sphingomyelinase: an in vitro study

Digestion of dietary sphingomyelin (SM) is catalyzed by intestinal alkaline sphingomyelinase (SMase) and may have important implications in colonic tumorigenesis. Previous studies demonstrated that the digestion and absorption of dietary SM was slow and incomplete and that the colon was exposed to SM and its hydrolytic products including ceramide. In the present work, we studied the influences of glycerophospholipids and hydrolytic products of phosphatidylcholine (PC; i.e., lyso-PC, fatty acid, diacylglycerol, and phosphorylcholine) on SM hydrolysis induced by purified rat intestinal alkaline SMase in the presence of 10 mM taurocholate. It was found that various phospholipids including PC, phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylethanolamine (PE), and phosphatidic acid (PA) inhibit alkaline SMase activity in a dose-dependent manner, with the degree of inhibition being in the order PA > PS > PI > PC > PE. Similar inhibition was also seen in a buffer of pH 7.4, which is close to the physiologic pH in the middle of the small intestine. When the effects of hydrolytic products of PC were studied, lyso-PC, oleic acid, and 1,2-dioleoyl glycerol also inhibited alkaline SMase activity, whereas phosphorylcholine enhanced SMase activity. However, in the absence of bile salt, acid phospholipids including PA, PS, and PI mildly stimulated alkaline SMase activity whereas PC and PE had no effect. It is concluded that in the presence of bile salts, glycerophospholipids and their hydrolytic products inhibit intestinal alkaline SMase activity. This may contribute to the slow rate of SM digestion in the upper small intestine.

Herpes simplex virus infection blocks events in the G1 phase of the cell cycle

Infection of cells in G1 phase with herpes simplex virus (HSV) prevents their progression into S phase (de Bruyn Kops, A., and Knipe, D. M., 1988, Cell 55, 857-868). We have examined G1-phase events in infected cells to determine whether this effect was the result of inhibition of G1 phase progression or of entry into S phase. We observed that HSV infection decreased pRb phosphorylation and induced a new phosphorylated form of pRb. Furthermore, HSV infection prevented the normal G1 increases in cyclin D1 and D3 protein levels, and blocked the normal G1 appearance of new electrophoretic forms of cdk2 and cdk4. Thus, HSV infection inhibits several events that normally occur in the cell cycle during G1 phase, arguing that the HSV-induced block in the cell cycle occurs in early to mid-G1 phase.

Increased apoptosis in the heart of genetic hypertension, associated with increased fibroblasts

OBJECTIVE

The present studies were undertaken to identify apoptosis in cardiomyocytes of genetic hypertension and to study the relationship among apoptosis, aging and blood pressure, and the effect of angiotensin-converting enzyme (ACE) inhibitors on apoptosis.

METHODS

Apoptosis in the hearts of spontaneously hypertensive rats (SHR) was identified by electron microscopy (EM) and DNA laddering, and quantified from age 3 weeks to 64 weeks in comparison with normotensive rats (WKY). Fibroblasts and protein products of Bcl-2 and Bax were measured by quantitative immunohistochemistry. SHR were treated with ramipril, an ACE inhibitor.

RESULTS

The results showed that: (1) ultrastructural characteristics of apoptosis were observed in cardiomyocytes of SHR, with shrinkage of the cell and condensation of the cytoplasm and chromatin. A DNA ladder was shown; (2) a significant increase in apoptosis in SHR began as early as age 4 weeks and reached a plateau at 16 weeks and maintained at high levels up to 64 weeks. Blood pressure (BP) in SHR started to increase significantly at age 5 weeks; (3) fibroblasts were significantly increased in the heart of SHR; (4) the ratio of Bcl-2/Bax was significantly reduced in SHR; and (6) ramipril effectively reduced apoptosis and fibroblasts, and increased the ratio of Bcl-2/Bax.

CONCLUSION

Apoptosis occurs in the cardiomyocytes of genetic hypertension although fibroblasts are increased, and a significant, age-dependent increase in apoptosis is observed. The increase in apoptosis occurs before the difference in blood pressure is detectable. The ACE inhibitor ramipril may be useful for prevention of apoptosis in the heart.

Direct comparison of liposomal doxorubicin with or without polyethylene glycol coating in C-26 tumor-bearing mice: is surface coating with polyethylene glycol beneficial?

Sterically stabilized liposome is characterized by a surface coating of polyethylene glycol (PEG) or other polymers that can reduce opsonization of the liposome by plasma proteins. It has a higher plasma area under the concentration-time curve (AUC), which is believed to correlate with better therapeutic efficacy. However, the presence of large molecules on the liposomal surface may reduce the interactions of liposomes with cells and hinder entry of liposomes into the tumor tissue. Using a stable liposomal system composed of distearoyl phosphatidylcholine/cholesterol, we examined the effect of PEG (Mr 2000) on the pharmacokinetics and on the efficacy of liposomal doxorubicin with C-26 syngeneic tumor model in BALB/c mice. The plasma AUC of liposomal doxorubicin with 6 mol-% PEG-modified distearoyl phosphatidylethanolamine (PEG-DSPE) was approximately twice that of liposomal doxorubicin without PEG at various dosages, regardless of whether the mice were tumor-bearing. Paradoxically, the group of mice treated with liposomal doxorubicin without PEG had higher tumor doxorubicin concentrations. The 72-h tumor AUC was 1.44 times that of liposomal doxorubicin with 6% PEG-DSPE. The tumor-accumulation efficiency (AUC(Tumor)/AUC(Plasma)) of liposomal doxorubicin without PEG was 0.87, and this was more than twice that of the liposomal doxorubicin with 6% PEG-DSPE (0.31). At a dose of 10 mg/kg, although both liposomal groups were better than the free drug group in terms of clinically relevant parameters, including toxicity, tumor shrinkage, and survival, there was no difference between the two liposomal drug groups. In this stable liposome system, surface coating with PEG offered no benefit for liposomal doxorubicin in the C-26 tumor model. To enhance the therapeutic index of liposomal doxorubicin, simply increasing plasma AUC by surface coating with PEG may not be satisfactory.

The correlativity analysis of six methods of detecting apoptosis

The aim of this study was to compare six methods of detecting apoptosis induced by extracellular adenosine triphosphate (ATP) in human leukemic lymphocytes with purinergic P2Z receptors. These methods used were electron microscopy (EM), detection of internucleosomal DNA fragmentation by agarose gel electrophoresis, autoradiographic analysis of DNA fragmentation, in situ labeling of DNA strand breaks with fluorescein dUTP and exogenous terminal deoxynucleotidyl transferase (TUNEL), quantitation of 3'-ends of DNA breaks by labeling with alpha32PdCTP(TdT assay), and quantitation of apoptotic cells with fluorescein-annexin V using flow cytometry (FCA). We found EM and detection of DNA ladder pattern by agarose gel electrophoresis to b specific, but lacking in sensitivity. The combination of autoradiography and gel electrophoresis gave an increase in sensitivity of at least 50 fold although, of all the methods, the TdT assay was shown to be most sensitive. The four methods for quantifying apoptosis-EM, FCA, TUNEL and TdT assay proved to be reliable and gave statistically similar results on apoptotic lymphocytes. These observations indicate it is essential to combine specific, sensitive and quantitative techniques in detecting apoptosis.

Oligopeptide-repeat expansions modulate 'protein-only' inheritance in yeast

The yeast [PSI+] element represents a new type of genetic inheritance, in which changes in phenotype are transmitted by a 'protein only' mechanism reminiscent of the 'protein-only' transmission of mammalian prion diseases. The underlying molecular mechanisms for both are poorly understood and it is not clear how similar they might be. Sup35, the [PSI+] protein determinant, and PrP, the mammalian prion determinant, have different functions, different cellular locations and no sequence similarity; however, each contains five imperfect oligopeptide repeats-PQGGYQQYN in Sup35 and PHGGGWGQ in PrP. Repeat expansions in PrP produce spontaneous prion diseases. Here we show that replacing the wild-type SUP35 gene with a repeat-expansion mutation induces new [PSI+] elements, the first mutation of its type among these newly described elements of inheritance. In vitro, fully denatured repeat-expansion peptides can adopt conformations rich in beta-sheets and form higher-order structures much more rapidly than wild-type peptides. Our results provide insight into the nature of the conformational changes underlying protein-based mechanisms of inheritance and suggest a link between this process and those producing neurodegenerative prion diseases in mammals.

The relationship between apoptosis and spontaneous hypertension

OBJECTIVE

To explore the relationship between apoptosis and spontaneous hypertension, and the effect of angiotensin converting enzyme (ACE) inhibitor on apoptosis.

METHODS

Male spontaneously hypertensive rats (SHR) and normotensive control rats (WKY) at different ages were used, meanwhile, the treatment of SHR with ramipril, an inhibitor of ACE was administered orally (1 mg.kg-1.d-1) to SHR from 3 to 10 or from 5 to 10 weeks of age. Apoptosis in cardiomyocytes of SHR was quantified by a maximal labeling (Lmax) method and the characteristic features of apoptosis were identified by electron microscopy (EM), in situ labeling of DNA strand breaks with terminal deoxynucleotidyl transferase mediated dUTP end labeling (TUNEL) and autoradiographic analysis of DNA fragments.

RESULTS

The results of a quantitative method showed an age-dependent increase in apoptosis in the cardiac tissues of SHR. A significant increase in DNA breaks occurred as early as 4 weeks and continued to increase up to a plateau at 16 weeks in the cardiac tissue of SHR whereas there was no significant change in apoptosis in WKY up to 64 weeks. Moreover, after the treatment of SHR with ramipril, an inhibitor of angiotensin converting enzyme (ACE), from 3 to 10 or from 5 to 10 weeks of age, the DNA fragmentation as well as blood pressure (BP) was reduced significantly compared with that of untreated SHR (P < 0.01), and similar to that of the control WKY.

CONCLUSION

There is a significant increase in the apoptosis of SHR cardiac tissues with increasing age, and ramipril can significantly prevent the increase of apoptosis and in blood pressure, which demonstrates that apoptosis may be involved in the pathogenesis of genetic hypertension. The inhibition of apoptosis as well as hypertension by ACE inhibitors may open a new avenue for developing therapeutic approach for hypertension.

Stromal-epithelial interactions in the cornea

Stromal-epithelial interactions are key determinants of corneal function. Bi-directional communications occur in a highly coordinated manner between these corneal tissues during normal development, homeostasis, and wound healing. The best characterized stromal to epithelial interactions in the cornea are mediated by the classical paracrine mediators hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF). HGF and KGF are produced by the keratocytes to regulate proliferation, motility, differentiation, and possibly other functions, of epithelial cells. Other cytokines produced by keratocytes may also contribute to these interactions. Epithelial to stromal interactions are mediated by cytokines, such as interleukin-1 (IL-1) and soluble Fas ligand, that are released by corneal epithelial cells in response to injury. Other, yet to be identified, cytokine systems may be released from the unwounded corneal epithelium to regulate keratocyte viability and function. IL-1 appears to be a master regulator of corneal wound healing that modulates functions such as matrix metalloproteinase production, HGF and KGF production, and apoptosis of keratocyte cells following injury. The Fas/Fas ligand system has been shown to contribute to the immune privileged status of the cornea. However, this cytokine-receptor system probably also modulates corneal cell apoptosis following infection by viruses such as herpes simplex and wounding. Pharmacologic control of stromal-epithelial interactions appears to offer the potential to regulate corneal wound healing and, possibly, treat corneal diseases in which these interactions have a central role.

Methanol-related deaths in Ontario

OBJECTIVE

Methanol poisoning accounts for several deaths annually in the province of Ontario. Our study was aimed at identifying the associated epidemiological factors for fatal outcomes following methanol poisoning in order to develop preventative strategies.

METHODS

The records of the Ontario Provincial Coroner's Office were reviewed retrospectively for all poison-related, alcohol-related, and chronic alcohol use-related deaths for the period of January 1, 1986 to December 31, 1991. Age, gender, reason for ingestion (accidental or intentional), and source of methanol for each victim were recorded.

RESULTS

There were 43 fatalities during this period, 39 males and 4 females with a mean age of 45 years (range 18-80). Suicide attempts accounted for 21 (49%) cases while the remaining 22 (51%) deaths were classified as accidental. Fourteen (64%) of these 22 patients consumed products labeled as methyl alcohol or wood alcohol as a substitute for ethanol. In 3 cases, the accidental ingestion was the direct result of methanol being improperly stored in containers normally associated with ethanol. The remaining 5 patients were poisoned through the consumption of liquor from illicit sources.

CONCLUSIONS

Over half of the methanol-related deaths in Ontario are accidental and potentially preventable. Possible preventative strategies include mandatory product relabeling to eliminate the word alcohol, enhanced public education, and the addition of aversive agents to methanol-containing commercial products.

Corneal epithelium-specific mouse keratin K12 promoter

Keratins are structural proteins expressed by epithelial cells. Approximately 30 different keratin proteins have been identified, each with a specific expression pattern in different epithelial cells. The tissue-specific promoter of several keratin genes have been used to direct the expression of transgenes in animals. Keratin K12 and K3 are expressed in differentiated and stratified corneal epithelium, although the relative expression of each appears to vary between species. We targeted the mouse K12 keratin gene in order to develop a tissue-specific promoter that could be utilized to study the functions of genes of interest expressed in the corneal epithelium. Three 5' truncated fragments of the keratin K12 promoter (1.03, 0.71 and 0.25 Kb) showed higher functional and tissue-specific promoter activity in a human corneal epithelial cell line than other cell lines. The 0.25 Kb K12 promoter fragment was also active in cultured rabbit corneal epithelial cells. Thus, increased expression in corneal epithelial cells directed by fragments of the mouse K12 promoter extended across species lines. The paired box homeotic gene 6 (PAX-6), which is involved in controlling eye development, stimulated the activity of keratin K12 promoter.

Molecular cloning and nucleotide sequence of 3'-terminal region of classical swine fever virus LPC vaccine strain

A cDNA of the 3'-terminus of classical swine fever virus (LPC vaccine strain) was cloned and sequenced. The 3431 nucleotides and deduced amino acid sequences were compared with those of other pestiviruses, and the similarity of nucleotide sequences and deduced amino acid sequences were found to be 84-95% and 95-98%, respectively. Similar to other isolates of classical swine fever virus, the sequenced region included the non-structural gene p58 (NS5A) and part of p76 (NS5B) gene. The p76 gene of LPC vaccine strain also contained a highly conserved motif G-D-D (Gly-Asp-Asp) that is present in the RNA replicase of positive-stranded RNA viruses. With the sequence data currently available, we carried out a phylogenetic analysis and obtained a genealogical relationship among members of the classical swine fever virus.

Imbalanced expression of functionally different WT1 isoforms may contribute to sporadic unilateral Wilms' tumor

Functional loss of the product of the Wilm's tumor suppressor gene (wt1) has been identified in subsets of familial Wilms' tumors. Previously, four alternative splice products of WT1 were recognized and each was found to regulate transcription of effector genes differently, suggesting that disruption of the normal ratio of these spliced products will disrupt the normal expression patterns of WT1 effector genes and perhaps lead to Wilms' tumor. In support of these suggestions, we found that four of seven cases of sporadic unilateral Wilms' tumor had striking differences in the ratios of the spliced products of WT1 compared with each other and normal kidney. These data indicate that in addition to structural mutations, alterations in the relative amounts of the mature WT1 isoforms may also be important in the etiology of sporadic Wilms' tumor.

Characterization of a soluble KGF receptor cDNA from human corneal and breast epithelial cells

PURPOSE

Keratinocyte growth factor (KGF) is a member of the fibroblast growth factor (FGF) family FGF-7. It exhibits potent mitogenic activity for epithelial cells, including corneal and mammary epithelial cells. A messenger RNA has been reported that is generated by alternative splicing of bek that putatively codes only for the extracellular ligand-binding domain of KGF receptor (soluble KGF receptor). In the present study, the expression of the mRNA coding for this alternative bek transcript was examined and the corresponding protein characterized.

METHODS

Alternative messenger RNA transcripts were detected in various cell lines or tissues using reverse transcription-polymerase chain reaction (RT-PCR) and RNase protection assay. NIH/3T3 fibroblast cells and 293 kidney embryonic epithelial cells were stably transfected with soluble KGF receptor cDNA and transmembrane KGF receptor cDNA. Soluble KGF receptor protein was produced using a baculovirus-insect expression system. Soluble KGF receptor protein was detected using western and dot blot analyses. Binding assays and cross-linking labeling were used to determine the affinity and specificity of soluble KGF receptor. A mitogenic assay was performed to examine the function of the soluble KGF receptor.

RESULTS

The soluble KGF receptor mRNA was primarily expressed in epithelial cells, including cells from the cornea and breast. Cross-linking labeling and affinity-binding assays with 125I-KGF showed that the soluble KGF receptor bound KGF (FGF-7) but not FGF-1 or FGF-2. Soluble KGF receptor was detected in the culture medium of cells stably transfected with soluble KGF receptor cDNA but not with transmembrane KGF receptor cDNA, suggesting that the soluble receptor was generated by mRNA splicing and probably not by proteolysis or posttranslational processing. Soluble KGF receptor inhibited KGF binding to transmembrane KGF receptor and DNA synthesis in BALB/MK epidermal keratinocytes in response to KGF, suggesting that soluble KGF receptor expression could provide a mechanism for the cell to downregulate responses to KGF.

CONCLUSIONS

A truncated soluble KGF receptor expressed in corneal and other epithelial cells probably functions to downregulate the response of the cell to KGF.

Augmented effects of methionine and cholesterol in decreasing the elastic lamina while thickening the aortic wall in the rat aorta

1. Patients with an elevated plasma level of either homocysteine or cholesterol are at increased risk of cardiovascular disease. Both methionine, the precursor of homocysteine, and cholesterol are found primarily in the same foods; therefore we investigated the effect of methionine feeding alone, cholesterol feeding alone, and both, on the thickness of the aortic wall and the aortic elastic lamina of normotensive animals.2. Twenty normotensive rats were divided into four groups of five animals. The following diet was administered for 15 weeks: normal chow; normal chow supplemented with 2% methionine; normal chow supplemented with 2% cholesterol; normal chow supplemented with 2% methionine+2% cholesterol.3. The results showed a 3-fold decrease (P<0.003) in the aortic elastic lamina in the 2% methionine group and a 2.5-fold decrease in the 2% cholesterol group compared with the normal chow group. There was a 9-fold (P<0.0003) decrease in the 2% methionine+2% cholesterol group compared with the normal chow group. Furthermore, feeding with methionine plus cholesterol significantly increased aortic wall thickness compared with the methionine group, cholesterol group or control.4. These results demonstrate an augmented effect of cholesterol plus methionine in the deterioration of the aortic elastic lamina, and furthermore, the combination of these two agents increases the thickness of the aortic wall. The results indicate a more important role for these two agents in combination than for either agent alone.

Activation of Stat3 by v-Src is through a Ras-independent pathway

V-Src induces tyrosine phosphorylation of various cellular proteins and activates a number of signaling molecules including the Jak family of proteins tyrosine kinases and Stat (signal transducers and activators of transcription) proteins. Many cellular effects elicited by v-Src are mediated through Ras, a molecular switch linking growth factor receptors and non-receptor tyrosine kinases to many downstream effectors. In this report, we demonstrated that v-H-Ras and v-Src both induced cellular transformation. However, the activation of Jak1 and Stat3 were only observed in v-Src transformed cells. Using reporter gene assays, we further showed that activation of Stat3 and possibly of Jak1 by v-Src were mediated through a Ras-independent pathway. As Stat3 activation has recently been shown to be required for cellular transformation by v-Src, our results suggest that activation of the Jak-Stat pathway may serve as a modulator in some but not all transformation processes.

A point mutation within exon 5 of the WT1 gene of a sporadic unilateral Wilms' tumor alters gene function

The Wilms' tumor suppressor gene, wt1, encodes a zinc-finger transcription factor, WT1, that represses transcription of a number of growth-promoting genes and inhibits cell growth. The transcripts of wt1 undergo two alternative splicing events, giving rise to four isoforms of mRNA in constant ratios. The first alternative splice introduces an extra exon 5, which encodes 17 amino acid residues inserted between the transcription regulatory domain and the DNA binding domain of WT1. Previously, we demonstrated that the 17-amino acid domain functioned as a transcription repressor when it was fused with the DNA binding domain of WT1. We have now identified a point mutation within exon 5 of wt1 in a sporadic unilateral Wilms' tumor patient. The mutation changes the last of the 17 amino acids from asparagine to serine. The protein isoform of WT1 carrying this mutation exhibited a 2-3-fold lower transcription-repressing activity than wild-type WT1 in transient cotransfection assays. The mutation also decreased growth-inhibiting activity of WT1 in two osteosarcoma cell lines, U2OS and Saos-2. By diminishing transcription-repressing and growth-inhibiting activities of WT1, this naturally occurring mutation within exon 5 of wt1 may disturb the normal function of the protein and lead to the uncontrolled cell growth characteristic of Wilms' tumor.

Prognostic factors in patients with methanol poisoning

OBJECTIVE

To identify prognostic factors in methanol poisoning and determine the effect of medical interventions on clinical outcome.

METHODS

Retrospective review of all patients treated for methanol poisoning from 1982 through 1992 at The Toronto Hospital. Presenting history, physical examination, results of laboratory tests, medical interventions, and final outcomes after hemodialysis were abstracted.

RESULTS

Of 50 patients treated for methanol poisoning, 18 (36%) died, 32 (64%) survived. Seven of the 32 survivors sustained visual sequelae (22%), the remaining 25 (78%) recovered completely. Patients presenting with coma or seizure had 84% (16/19) mortality compared to 6% (2/31) in those without (p < 0.001). Initial arterial pH < 7 was also associated with significantly higher mortality (17/19, 89% vs 1/31, 3%, p < 0.001). There were no differences in time from presentation to dialysis between survivors and fatalities (8.4 +/- 3.6 vs 7.6 +/- 3.5 hours, p = 0.47). The deceased patients had higher mean methanol concentration than the survivors (83 +/- 53 vs 41 +/- 25 mmol/L, p = 0.004). Subgroup analysis of 19 patients presenting with visual symptoms who survived showed prolonged acidosis (5.4 +/- 2.3 vs 3.0 +/- 2.1 hours, p = 0.06) in those with persistent visual sequelae.

CONCLUSIONS

Coma or seizure on presentation and severe metabolic acidosis, in particular initial arterial pH < 7, are poor prognostic indicators in methanol poisoning. Survivors presented with lower methanol concentrations. Patients with residual visual sequelae had more prolonged acidosis than those with complete recovery. Future studies will be needed to confirm the effect of correction of acidosis on final clinical outcome.

Effect of homocysteine and cholesterol in raising plasma homocysteine, cholesterol and triglyceride levels

A high plasma homocysteine level is a newly regarded risk factor for coronary artery disease. We report a synergistic effect of homocysteine plus cholesterol feeding on further raising total plasma homocysteine, cholesterol and triglycerides levels than each agent alone, which further enhances the risk of coronary artery disease.

Cloning, expression and sequence analysis of the classical swine fever virus nucleocapsid protein

The DNA complementary to the 5'-terminal 1929 nucleotides of classical swine fever virus (CSFV; alias hog cholera virus, HCV) LPC vaccine strain RNA was cloned and sequenced. The sequence encompasses a 5'-noncoding region (NCR) of 264 nucleotides and an open reading frame (ORF) of 1665 nucleotides. The cloned sequence contains genes of four viral proteins, P23, nucleocapsid (core) protein, E0 and part of E1 proteins. Alignment of the 5'-terminal 1929 nucleotides of LPC strain with other strains of CSFV showed well conservation and a homology as high as 84-95% was found between these strains. The cDNA of CSFV-LPC core was cloned into an expression vector, and a fusion protein of 38.5 kDa was obtained which reacted strongly to CSFV antiserum. Purification of the core fusion protein was achieved by a single-step affinity chromatography and the purified product could be recognized by the sera of CSFV-infected swine in ELISA assay. Phylogenetic analysis of the 5'-terminal 1929 nucleotides between pestiviruses revealed that the 5'-end region seems to be suitable for differentiation of different strains of CSFV.

Expression of the glycoprotein E2 of the classical swine fever virus in Escherichia coli

The glycoprotein E2 sequences of classical swine fever virus (strain p97) were cloned, sequenced and expressed in E. coli. Result from SDS-polyacrylamide gel electrophoresis analysis of expressed proteins revealed the presence of a prominently stained band corresponding to a molecular mass of 61 kDa, which is in agreement with the predicted size from the DNA sequence. The recombinant E2 protein contained an aminoterminal tag of six histidines that could be used for purification by the nickel chelate affinity chromatography. The elution fractions of the expressed protein also contain additional bands of 40 and 35 kDa proteins, indicating proteolytic cleavages might occur. Our Western blotting result also supported that the expression of the recombinant E2 protein of the classical swine fever virus were accomplished.

A novel immunohistochemical semiquantitative technique for endothelial constitutive nitric oxide synthase immunoreactivity in rat coronary artery

It has been difficult to quantify protein production in small pathological specimens by conventional techniques. We describe a new method for semiquantification of immunohistochemical staining, which involves application of the enzyme-labeled avidin (LAB) technique, coupled with an ultra-sensitive and fast chemiluminescent substrate for alkaline phosphatase. The entire procedure can be completed in less than 3 hr. The final step involves X-ray film exposure for 30 min, and the optical density of the subsequent images is examined with a microcomputer imaging device. The optical densities are translated into relative protein concentrations by a reference standard curve, obtained via an immunoblot. To establish a model for semiquantification of endothelial constitutive nitric oxide synthase (eNOS) protein, we compared the coronary arteries of WKY rats fed a normal chow diet to the coronary arteries of WKY rats fed a cholesterol diet. Using this technique, we have found a relative 130-fold decrease in eNOS in the cholesterol-fed group compared to the normal chow-fed group.

The recombinant nucleocapsid protein of classical swine fever virus can act as a transcriptional regulator

The cDNA of the nucleocapsid (core) protein of classical swine fever virus (CSFV) was generated by reverse transcription-polymerase chain reaction (RT-PCR) and cloned into a eukaryotic expression vector. The effect of the recombinant core protein on the transcriptional regulation of cellular as well as viral promoters was studied. Using transient transfection assay, our results demonstrated that the core protein can activate the promoter of human heat shock protein 70 gene, and suppressed the SV40 early promoter. These findings indicate that the core protein appears to function not only as a viral structural protein but also as a regulator of gene expression. The implications of core proteins on the viral maturation are discussed.

A novel method for quantitative analysis of apoptosis

In the present study, we describe a method of quantifying DNA fragmentation. This assay is based on saturation labeling 3'-ends of DNA fragments with alpha(32)PdCTP in the presence of 2',3'-dideoxy-cytidine-5'-triphosphate (ddCTP) by terminal deoxynucleotidyl transferase (TdT). The saturation labeling of 3'-ends of DNA fragments was performed by adding different concentrations of alpha(32)PdCTP to a DNA sample, from which a maximal labeling (Lmax) and a kinetic parameter (Km) of the TdT reaction are calculated. The saturated labeling gives true quantitation that makes it possible to accurately compare quantities of DNA fragments among different samples. This method requires as little as 5 ng of DNA and increases the sensitivity of apoptotic DNA detection by at least 200-fold relative to the widely used ethidium staining method. The application of this method in an apoptosis study showed that (a) a time- and dose-dependent increase in the number of DNA strand breaks in apoptotic lymphocytes was induced by dexamethasone, and (b) age-dependent apoptosis occurred in the cardiac tissues of spontaneously hypertensive rats. Results of this assay were confirmed by the DNA ladder pattern exhibited after electrophoresis as well as the morphologic changes of apoptosis observed under electron microscopy and were very consistent with results obtained in quantifying apoptotic cells by flow cytometric analysis (r = 0.98, p = 0.002). Thus, this assay is quantitative, simple, sensitive, and useful for assessing apoptosis.

Protein memory through altered folding mediated by intramolecular chaperones

The 77-residue propeptide of subtilisin acts as an intramolecular chaperone that organizes the correct folding of its own protease domain. Similar folding mechanisms are used by several prokaryotic and eukaryotic proteins, including prohormone-convertases. Here we show that the intramolecular chaperone of subtilisin facilitates folding by acting as a template for its protease domain, although it does not form part of that domain. Subtilisin E folded by an intramolecular chaperone with an Ile(-48)-to-Val mutation acquires an 'altered' enzymatically active conformation that differs from wild-type subtilisin E. Although both the altered and wild-type subtilisins have identical amino-acid sequences, as determined by amino-terminal sequencing and mass spectrometry, they bind their cognate intramolecular chaperones with 4.5-fold greater affinity than non-cognate intramolecular chaperones, when added in trans. The two subtilisins also have different secondary structures, thermostability and substrate specificities. Our results indicate that an identical polypeptide can fold into an altered conformation through a mutated intramolecular chaperone and maintains memory of the folding process. Such a phenomenon, which we term 'protein memory', may be important in investigations of protein folding.

Essential parameters in particle sizing by integral transform inversions

We show that integral transform inversions for Fraunhofer-diffraction particle sizing possess an important feature that has useful implications. The selection of three angular parameters, Dtheta (angular resolution), theta(min) (minimum scattering angle), and theta(max) (maximum scattering angle), necessary for reconstructing a given kind of particle size distribution without undergoing mathematical limits that contradict the Fraunhofer theory and exceed practical measurement limitations, depends inverse-linearly on the optical size parameter chi, chi = 2pia/lambda (a, particle radius; lambda, wavelength). Two series of numerical experiments, in which the Chin-Shifrin inversion is used, are performed to assess the reconstruction of original discontinuous (narrow-type) and continuous (board-type) particle size distributions from simulated Fraunhofer-diffracted patterns, assuming linear- and log-scaled light detector configurations, respectively. New and useful findings regarding the roles of these three key angular parameters in the Chin-Shifrin inversion process, including general criteria relating the chi and the selections of Dtheta and theta(max) for effective size retrieval, were obtained.

Perindopril chronically inhibits angiotensin-converting enzyme in both the endothelium and adventitia of the internal mammary artery in patients with ischemic heart disease

BACKGROUND

ACE inhibitors are widely used in treating hypertension and heart failure, but the sites and mechanisms of ACE inhibition in human blood vessels are not understood. The present study was undertaken to assess the sites and extent of in vivo inhibition of ACE by long-term perindopril treatment in different layers of the internal mammary artery in patients with ischemic heart disease.

METHODS AND RESULTS

Sixteen patients with ischemic heart disease were treated either with perindopril (4 mg/d PO) for up to 36 days before surgery (n = 9) or without the inhibitor as control subjects (n = 7). The segments of the internal mammary artery were collected for measurement of vascular free and total ACE by quantitative in vitro autoradiography with 125I-351A binding. The patients treated with perindopril had lower plasma ACE (P < .001) and plasma angiotensin (Ang) II-to-Ang I ratio (P < .05). In the internal mammary artery, free ACE was similarly inhibited by perindopril in the endothelium (P < .05) and adventitia (P < .05), and the free ACE-to-total ACE ratio, an index of ACE inhibition, was markedly decreased by perindopril in parallel in the endothelium (P < .001) and adventitia (P < .001). Moreover, plasma ACE correlated highly with vascular ACE in the endothelium (r = .85, P < .001) or adventitia (r = .78, P < .001), and mean arterial pressure correlated significantly with free ACE in the endothelium (r = .52, P < .05) or adventitia (r = .53, P < .05) and with the plasma Ang II-to-Ang I ratio (r = .53, P < .05). Light microscopic autoradiographs of 125I-351A binding revealed a marked inhibition of ACE by perindopril in both layers of the vascular wall.

CONCLUSIONS

The present demonstrates that long-term administration of perindopril potently inhibits both endothelial and adventitial ACE to a comparable degree in the human internal mammary artery. These results indicate that perindopril effectively penetrates the vascular wall to inhibit ACE in the adventitia, thus providing evidence that perindopril may be beneficial in inhibiting both circulating Ang II and its local formation in the vascular wall.

In vivo gene transfer by intravenous administration of stable cationic lipid/DNA complex

PURPOSE

A stable cationic lipid/DNA complex has been developed for in vivo gene transfer. The formulation capitalizes on a previously described procedure to obtain stable lipid/DNA complexes for in vitro gene transfer (1).

METHODS

Conditions for DNA/lipid complex formation were modified to yield a DNA concentration of 1 mg/ml. Heat stable alkaline phosphatase (AP) under a CMV promoter was used as a reporter gene.

RESULTS

The resulting complex was completely insensitive to serum inactivation. Tail vein injection of a 80 micrograms DNA into Balb C mice yielded significant levels of reporter enzyme activity in the lung, heart, spleen, muscle, and liver. Less AP activity was observed in the kidney. No AP activity was observed in blood, bone marrow or brain. A titration of the lipid (DOSPA) to DNA-nucleotide ratio showed the optimal molar ratio for in vivo gene transfer to be 1/1. Using this ratio in a dose response study showed approximately 80 micrograms of DNA/mouse yielded the highest level of gene expression. Using this dose at a 1/1 lipid to DNA nucleotide ratio, the time course for alkaline phosphatase activity was determined. Maximal AP activity was observed 24 hours after injection for all tissues. By day 5, the activity dropped approximately 10 fold for all tissues. By day 7, residual activity was detected in the lung, heart, and muscle. Histology of the lung showed both interstitial and endothelial cells to be transfected. In all other tissues, however, endothelial cells were the only transfected cell type.

CONCLUSIONS

These results demonstrate that reformulation of an existing cationic lipid can result in the formation of a stable lipid/DNA complex, which is able to reproducibly transfect lung, heart, spleen, and liver upon intravenous administration.

Self-seeded fibers formed by Sup35, the protein determinant of [PSI+], a heritable prion-like factor of S. cerevisiae

The [PSI+] factor of S. cerevisiae represents a new form of inheritance: cytosolic transmission of an altered phenotype is apparently based upon inheritance of an altered protein structure rather than an altered nucleic acid. The molecular basis of its propagation is unknown. We report that purified Sup35 and subdomains that induce [PSI+] elements in vivo form highly ordered fibers in vitro. Fibers bind Congo red and are rich in beta sheet, characteristics of amyloids found in certain human diseases, including the prion diseases. Some fibers have distinct structures and these, once initiated, are self-perpetuating. Preformed fibers greatly accelerate fiber formation by unpolymerized protein. These data support a "protein-only" seeded polymerization model for the inheritance of [PSI+].

Regulation of acetylcholine release by presynaptic nicotinic receptors at developing neuromuscular synapses

Autoregulation of synaptic transmission in the nervous system is one of the homeostatic processes by which the transmission can be regulated according to varied physiological conditions. The neuromuscular cocultures of Xenopus laevis embryos were used to investigate the role of presynaptic nicotinic receptors in the autoregulation of developing motoneurons. The bath application of 2 microM nicotine had no significant effect on the frequency of spontaneous synaptic currents (SSCs). However, nicotine markedly increased the SSC frequency in the presence of low concentrations of glutamate (2 microM) or ATP (0.15 mM) or high K+ (8 mM), which only slightly increased the frequency of spontaneous acetylcholine (ACh) secretion. Carbachol but not oxotremorine was similar to nicotine in the positive regulation of spontaneous ACh release. Treatment with alpha-bungarotoxin, hexamethonium, d-tubocurarine, or mecamylamine, which only slightly inhibited the SSC amplitude, effectively antagonized the increasing effect of nicotine plus glutamate on SSC frequency. Local perfusion of isolated neurons with nicotine induced an inward current at nerve terminal but not at soma, suggesting that nicotinic receptors localize at nerve terminals. Both d-tubocurarine and hexamethonium, which produced tetanic fade in adult neuromuscular preparations, did not show tetanic fade at embryonic neuromuscular junction. The bath application of alpha-bungarotoxin or hexamethonium but not 6-cyano-2,3-dihydroxy-7-nitroquinoxaline inhibited the frequency of SSCs at high-activity (>3 Hz) synapses. A P2-purinoceptor antagonist, suramin, or desensitizing P2-purinoceptor with alpha, beta-methylene ATP also reduced the frequency of SSCs at these high-activity synapses. These results suggest that nicotinic receptors, P2-purinoceptors and glutamate, receptors coexist at nerve terminals of developing motoneurons. The activation of presynaptic nicotinic receptors, which cooperates with either P2-purinoceptors or glutamate receptors, may greatly increase the spontaneous ACh secretion. Endogenously released ACh and ATP are both involved in the positive regulation of spontaneous transmitter secretion at developing neuromuscular synapses.