Structure, function and regulation of p63 and p73

The p53 tumor suppressor gene is one of the most frequently mutated genes in human cancers.1 p53 is a sequence-specific transcription factor and plays a critical role in activating the expression of genes involved in cell cycle arrest or apoptosis under conditions of genotoxic stress.2,3 For over two decades, p53 was thought to be the only gene of its kind in the vertebrate genomes. This strong conviction, which was widely accepted in the p53 field, has now been proven to be incorrect. Two genes, referred to as p63 and p73, have been found to encode proteins that share a significant amino-acid identity in the transactivation domain, the DNA binding domain, and the oligomerization domain with p53. In the short period since their cloning, a number of investigators have reported on the structure, the function and the regulation of p63 and p73. This review summarizes the current information on the p63 and the p73 genes, with a focus on the differences between the three members in this newly defined p53-gene family.

Optimization of plasmid maintenance in the attenuated live vector vaccine strain Salmonella typhi CVD 908-htrA

The broad objective of the research presented here is to develop a noncatalytic plasmid maintenance system for the stabilization of multicopy expression plasmids encoding foreign antigens in a Salmonella typhi live-vector vaccine strain such as CVD 908-htrA. We have enhanced the maintenance of expression plasmids at two independent levels. First, we removed dependence upon balanced-lethal maintenance systems that involve catalytic enzymes expressed from multicopy plasmids; we accomplished this through incorporation into expression plasmids of a postsegregational killing system based on the noncatalytic hok-sok plasmid addiction system from the antibiotic resistance factor pR1. We also included at least one naturally occurring plasmid partition function in our expression plasmids, which eliminates random segregation of these plasmids, thereby enhancing their inheritance and stability; to accomplish this, we incorporated either the par locus from pSC101, the parA locus from pR1, or both. We monitored the stability of optimized expression plasmids within CVD 908-htrA by quantitating expression of a variant of green fluorescent protein (GFPuv) by using flow cytometry. In this report, we demonstrate the utility of this novel plasmid maintenance system in enhancing the stability of our expression plasmids and go on to show that as the copy number of stabilized plasmids increases, the toxicity of GFPuv synthesis also increases. The implications of these observations for the rational design of immunogenic and protective bacterial live vector vaccines are discussed.

[Separation and determination of 1,5-benzothiazepines-alpha-chloro-beta-lactam with thin-layer chromatography]

A method for separation and determination of 1,5-benzothiazepines-alpha-chloro-beta-lactam in reaction mixture by thin-layer chromatography has been established. The operating conditions were: lambda 1 = 270 nm, lambda 2 = 310 nm, beam size: 1.2 mm x 1.2 mm, SX = 3. The calibration curve was linear in the range of 0.285-5.7 micrograms (r = 0.9952, n = 8) and the detectable limit was 0.114 microgram. The coefficient of variation of this method was less than 5% and the average recovery for beta-lactam was 96.75%. The method is simple and rapid.

Acetylation of MyoD directed by PCAF is necessary for the execution of the muscle program

p300/CBP and PCAF coactivators have acetyltransferase activities and regulate transcription, cell cycle progression, and differentiation. They are both required for MyoD activity and muscle differentiation. Nevertheless, their roles must be different since the acetyltransferase activity of PCAF but not of p300 is involved in controlling myogenic transcription and differentiation. Here, we provide a molecular explanation of this phenomenon and report that MyoD is directly acetylated by PCAF at evolutionarily conserved lysines. Acetylated MyoD displays an increased affinity for its DNA target. Importantly, conservative substitutions of acetylated lysines with nonacetylatable arginines impair the ability of MyoD to stimulate transcription and to induce muscle conversion indicating that acetylation of MyoD is functionally critical.

Mondor's disease in the breast

Mondor's disease, superficial thrombophebitis of the breast, is an uncommon self-limiting condition. Surgical procedures and trauma were the common known causes. The objective of this study was to evaluate the incidence of Mondor's disease in different breast operations in lower risk of breast cancer area over a 6-year period and to identify its causes, clinical features, related surgical factors and associated breast cancer. Eighty-four cases of Mondor's disease were obtained from 9657 new patients in the breast clinic of Kaohsiung Medical University Hospital between January 1991 and December 1996. The incidence per year was close (0.84%-0.96%) although the number has been increasing each year. In 23 cases, no definite cause was diagnosed, whereas in 61 cases, the disorder was secondary because the pathogenesis could be discerned. The identified causes included forty-three cases caused by breast surgery, two cases associated with breast cancer and sixteen cases with other benign causes. Although the incidence did not differ significantly between breast surgery (0.95%) and non-surgical causes (0.79%), the highest incidence, 1.52%, occurred when excision through circumareolar incision and tunnel procedure for cosmesis (25 cases in 1634 excisions) were used, and the lowest 0.69% when excisions through direct incision (14 cases in 2004 excisions) were performed. (P < 0.05) The other incidence rates were 1.56% in breast conserving surgery which is higher than 0.37% following mastectomy. The incidence of the disease was higher (4.28%) when the distance of the breast lesion was more than 3 cm from the areolar edge, compared to 1.20% for the 2 cm group and 0.32% for the 1 cm group (P < 0.05) in tunnel procedures. The incidence of Mondor's disease during breast surgery was not significantly different in different breast quardrants. Although Mondor's disease is a benign, self-limiting condition, a high incidence developed in the excision biopsy through circumareolar incision with tunnel procedure when the distance from the breast lesion to the areolar edge was more than 3 cm. To prevent this complication, the tunnel procedure in breast biopsy should be avoided. The incidence of Mondor's disease associated with breast cancer was low (2.4%) in the lower-incidence breast cancer area from this series, but awareness of the condition is recommended.

Assessment of decisions in the treatment of Helicobacter pylori-related duodenal ulcer: a cost-effectiveness study

AIMS

Many treatment trials for Helicobacter pylori have been reported but few have evaluated treatment in terms of both cost and effectiveness. It is important to find a therapy with a high eradication rate and low cost, especially in China. The aim of the study is to assess the efficiency of therapy for duodenal ulcers, including ulcer healing, H. pylori eradication and ulcer recurrence.

METHODS

Ninety-six consecutive patients with duodenal ulcers and H. pylori infection were randomly allocated into two groups: AMT group (amoxycillin + metronidazole + tagamet); OA group (omeprazole + amoxycillin). Side-effects were recorded during the treatment period. Endoscopic examinations were repeated at the 7th or 8th week to assess ulcer healing. Patients were followed up for 6 months and repeat endoscopy was performed. Ulcer healing rate, H. pylori eradication rate and ulcer recurrence rate were compared. All costs were recorded and a cost-effectiveness analysis was conducted.

RESULTS

In the AMT and OA groups, the ulcer healing rate was 83.7 and 93.5%, respectively (P = 0.27). The eradication rate of H. pylori was 65.1 and 69.6%, respectively and was significantly higher in patients with an ulcer diameter < or = 1 cm compared with those with an ulcer diameter > 1 cm, irrespective of treatment group. There was no difference in recurrence rate, duration of pain or the time lost because of the disease. Moderate or severe side-effects were found in 8.9% in AMT group and 6.5% in OA group. The cost of treatment for ulcer healing, H. pylori eradication and reduction in ulcer recurrence were all lower in the AMT group than in the OA group. Sensitivity analysis supported the result that AMT was more cost effective than OA.

CONCLUSIONS

The AMT therapy was more effective and less costly than the OA therapy, especially in patients with H. pylori-related duodenal ulcers < 1 cm diameter.

Mitochondrial DNA analysis of sympatric morphotypes of bottlenose dolphins (genus: Tursiops) in Chinese waters

The classification within the bottlenose dolphin (genus Tursiops) is controversial. Although many morphological variants exist, most authors have concluded that the genus is composed of a single species, Tursiops truncatus (Montagu 1821). Two distinct morphotypes of bottlenose dolphins, which have been referred to as T. truncatus and T. aduncus, exist in sympatry in Chinese waters. Comparisons of a 386-bp fragment of the mitochondrial DNA (mtDNA) control region (n = 47) indicated that the two sympatric morphotypes were genetically distinct, with seven fixed site differences and a sequence divergence of approximately 4.4%. Phylogenetic analyses using maximum likelihood, neighbour-joining and maximum parsimony approaches showed that the truncatus-type dolphins from Chinese waters were more closely related to Atlantic Ocean truncatus-type than to the sympatric aduncus-type dolphins. The Atlantic truncatus-type dolphins also shared the same diagnostic sites that separated Chinese truncatus-type from aduncus-type dolphins. The molecular data agreed completely with the morphological classifications of the specimens. This congruence is strong evidence that the sympatric morphotypes in Chinese waters are reproductively isolated and comprise two distinct species. These findings have important implications for the conservation of bottlenose dolphins in Chinese waters.

Synthetic peptide sequence from the C-terminus of the insulin-like growth factor-I receptor that induces apoptosis and inhibition of tumor growth

Although the type 1 insulin-like growth factor receptor (IGF-IR) is a potent inhibitor of apoptosis, its C-terminus sequence sends contradictory signals, including a clearly proapoptotic signal. We have synthesized a peptide, peptide 2, having the sequence of the IGF-IR from residue 1282 to residue 1298 (C-terminus of the beta subunit). To favor its uptake into cells, we linked it to a stearic acid moiety at its NH-terminus. Peptide 2 is taken up by the cells, where it inhibits DNA synthesis and causes apoptosis, while a scrambled peptide (with stearic acid) and peptide 2 without stearic acid are completely ineffective. Peptide 2 is more effective when cells are in anchorage-independent conditions than when they grow in monolayer cultures. Accordingly, we find that peptide 2 can inhibit the growth of a human prostatic cell line in nude mice. The proapoptotic effect of peptide 2 is inhibited by the expression of Bcl-2 or by a dominant negative mutant of caspase 9. These and other data indicate that peptide 2 does not seem to be competing directly with the IGF-IR for common substrates, but that its proapoptotic effect is related to its ability to activate the caspase cascade.

Interactions of EGF and ornithine decarboxylase activity in the regulation of gastric mucus synthesis in cigarette smoke exposed rats

Cigarette smoking has been shown to aggravate ulceration and delay ulcer healing. Smokers had a lower level of mucus in their stomachs. In the present study, we examined whether cigarette smoke or its extract reduced mucus production through the suppression of epidermal growth factor (EGF) associated with the reduction of polyamine biosynthesis both in vivo and in vitro. Ornithine decarboxylase (ODC) activities and mucus synthesis were determined in rat gastric mucosa and in human MKN-28 cells. Incubation of MKN-28 cells with EGF (0.01-1.00 ng/mL) significantly increased mucus synthesis in vitro, which was accompanied by an increase of ODC activity. Removal of salivary glands decreased the circulated EGF level and induced a significant reduction of mucus-secreting layer thickness in the gastric mucosa. Cigarette smoke or its extract markedly decreased mucus synthesis in vivo and in vitro, both of which could be completely reversed by intravenous administration of EGF (20 microg/kg) in rats or co-incubation with EGF (1 and 2 ng/mL) in MKN-28 cells. However, ODC activities, which were suppressed by cigarette smoke or its extract, were unaffected by intravenous administration of EGF in rats, or only partially reversed by co-incubation with EGF in MKN-28 cells. These findings indicate that both EGF and ODC activity represent two different entities in the modulation of cigarette smoking on gastric mucus synthesis. The action of EGF on mucus synthesis may only be partially if not dependent on ODC activity in the stomach.

The role of epidermal growth factor in gastric epithelial proliferation in portal hypertensive rats exposed to stress

BACKGROUND/AIMS

This study was designed to determine whether epidermal growth factor may have a role in the stomach of portal hypertensive rats after exposure to water immersion and restraint stress.

METHODOLOGY

Rats with portal hypertension (portal vein partial ligation) were studied to determine the proliferative response of the gastric epithelium to epidermal growth factor (EGF) during stress. The portal hypertensive rats received EGF (0, 10, 25, 50, and 100 microg/kg/day) subcutaneously for 7 days before water immersion restraint stress. Each rat was subjected to water immersion restraint stress for 6 hours, at the end of which the stomachs were excised to evaluate gross and microscopic mucosal damage, and gastric epithelial proliferation using proliferating cell nuclear antigen (PCNA) immunoreactivity.

RESULTS

The gross and microscopic mucosal damage were significantly greater in control or low dose EGF-pretreated (10 or 25 microg/kg/day) rats than in high dose EGF-pretreated (50 or 100 microg/kg/day) rats (p<0.01). These changes were accompanied by parallel alterations in the PCNA labeling index. The PCNA labeling index between high dose EGF-pretreated and control or low dose EGF-pretreated rats differed significantly (p<0.01).

CONCLUSIONS

This study clearly indicates that the influence of EGF on the proliferative response of the portal hypertensive (PHT) gastric epithelium to stress in rats was dose-dependent, suggesting an important role for EGF in the protection of PHT gastric mucosa from stress injury.

Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study

The age-adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital-based case-control study to clarify the nature of the association between physical activity, water intake and colorectal-cancer risk in Taiwan. A total of 163 subjects (aged 33-80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food-frequency and lifestyle-activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic-regression analysis. A strong inverse dose-response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02-0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure-time physical activity was 0.19 (95% CI, 0.05-0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon-cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure-time activity may reduce colon-cancer risk, not only in high-risk but also in low-risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal-cancer risk.

Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study

The age-adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital-based case-control study to clarify the nature of the association between physical activity, water intake and colorectal-cancer risk in Taiwan. A total of 163 subjects (aged 33-80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food-frequency and lifestyle-activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic-regression analysis. A strong inverse dose-response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02-0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure-time physical activity was 0.19 (95% CI, 0.05-0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon-cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure-time activity may reduce colon-cancer risk, not only in high-risk but also in low-risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal-cancer risk.

Benefits of endorectal ultrasound for management of smooth-muscle tumor of the rectum: report of three cases

Smooth-muscle tumor of the rectum is rare, and the therapeutic strategy is still controversial. Endorectal ultrasound was used to evaluate three patients with smooth-muscle tumor of the rectum. Endorectal ultrasound demonstrated a homogenous hypoechoic tumor without invasion to the perirectal tissue in two patients. The tumor was 5 cm in diameter in one patient and 4 cm in diameter in the other patient, and they were excised locally. Their histologic types were leiomyoma and leiomyosarcoma. The third patient had a recurrent leiomyosarcoma. Proctosigmoidoscopy found a linear lesion with ulcerated mucosa on the rectal wall. Endorectal ultrasound observed a hypoechoic solid tumor of 3.5 cm x 1 cm, which involved the mucosal, submucosal, and muscle layers of the rectal wall. Disruption of the first hypoechoic layer was identified. Abdominoperineal resection was performed. Endorectal ultrasound follow-up revealed no evidence of recurrence in any of these patients. Endorectal ultrasound can help to define the extent of disease and may be a useful adjunct in deciding about the appropriate surgical procedure in these diseases.

Induction of anaesthesia in patients with coronary artery disease: a comparison between sevoflurane-remifentanil and fentanyl-etomidate

In a prospective, randomized study, sevoflurane-remifentanil (Group SR) was compared with fentanyl-etomidate (Group FE) for induction of anaesthesia in patients with ischaemic heart disease. Cardiovascular stability, heart rate, mean arterial pressure, rate pressure product, rescue medications and associated myocardial ischaemia were measured. For Group SR (n = 20), anaesthesia was induced with vital capacity breaths of sevoflurane 5% in oxygen. After loss of consciousness, the inspired sevoflurane was reduced to 3% and remifentanil was administered as a 0.5 microgram.kg-1 bolus over 90 seconds (0.33 microgram.kg-1.min-1) followed by a 0.025 microgram.kg-1.min-1 infusion. After intubation, the inspired sevoflurane was reduced to 2%. For Group FE (n = 20), anaesthesia was induced with fentanyl 10.5 micrograms.kg-1 and etomidate 0.2 mg.kg-1 given 60 seconds later. Isoflurane 1% in oxygen was administered after loss of consciousness. Both groups received rocuronium and the trachea was intubated two minutes later. Sevoflurane gaseous induction was smooth, with cardiovascular stability comparable to fentanyl-etomidate. Significantly more patients in Group SR (P < 0.05) were on beta-blocking medication, and, overall, the HR and RPP was lower pre-intubation in Group SR. Remifentanil administration was associated with severe bradycardia in three patients and asystole in a fourth. All four patients were on beta-blocking medication and three of the four were on diltiazem. The study was terminated due to the high incidence of bradycardic/asystolic complications in Group SR.

Biochemical markers for assessment of bone metastases in patients with breast cancer

Breast cancer commonly metastasizes to bones, producing both osteolytic and osteoblastic deposits. Different markers for quantitative determination of bone turnover have been developed to evaluate bone metastases of breast cancer. The urinary deoxypyridinoline (Dpd), a crosslink product of collagen molecules found in bone and excreted in urine during bone degradation, and bone specific alkaline phosphatase (B-ALP), an isoenzyme localized in the membrane of osteoblasts and released in circulation during bone formation, were recently described as a group of markers of bone turnover in metastatic cancer. The urinary Dpd/creatinine (Cre) ratios and the serum B-ALP activity were determined in the samples from 148 patients who suffered from breast cancer (BC patients) with or without bone metastases, and 42 healthy women. For comparison, other biochemical markers, e.g. carcinoembryonic antigen (CEA), CA15-3, tissue polypeptide antigen (TPA), tissue polypeptide specific antigen (TPSA), and total alkaline phosphatase (T-ALP) in these samples were also evaluated. The results showed that there was a significant difference in urinary Dpd/Cre ratio between the control group and the patients with breast cancer (BC group) (mean +/- S.D., 5.69 +/- 1.26 vs. 8.19 +/- 3.95 nM/mM, P < 0.05). However, there was no significant difference between their B-ALP activities in the two groups. In addition, the BC patients with bone metastases showed elevated urinary Dpd/Cre ratios and B-ALP activities and ratios of (Dpd/Cre)/B-ALP in compare with BC patients without bone metastases (P < 0.05). Meanwhile, the urinary Dpd/Cre ratios (10.50 +/- 5.04 nmol/mmol) in the advanced stage of BC patients were higher than those in an early stage (7.45 +/- 3.23 nmol/mmol) (P < 0.05), but their serum B-ALP activities increased only in stage IV (P < 0.05). The urinary Dpd/Cre ratios also increased progressively according to the degree of bone metastases (P < 0.05), but their serum B-ALP activities only increased in severe bone metastases (P < 0.05). The results showed that the increase of a bone osteolytic activity took place earlier than that of a bone osteoblastic activity in the metastatic BC patients. In compare with other conventional markers, the best diagnostic efficiency of biochemical markers, analyzed by step wise discriminate analysis, was provided by CEA followed by Dpd/Cre ratio, CA15-3, TPA, TPSA, B-ALP and T-ALP. We conclude that showed the urinary Dpd/Cre ratio was a useful tumor marker to evaluate breast cancer with bone metastases.

Interaction of adeno-associated virus Rep78 with p53: implications in growth inhibition

Adeno-associated virus (AAV) is a nonpathogenic, single-stranded DNA virus belonging to the parvoviridae family. Onco-suppressive properties of AAV against adenovirus, a DNA tumor virus, have been well documented. Rep78, a major regulatory protein of AAV, is believed to be responsible for its antioncogenic properties. Most DNA tumor viruses disturb the cell cycle pathways by essentially abrogating the functions of p53. Here we present evidence that AAV acts as an antiproliferative agent against adenovirus by protecting the adenoviral-mediated degradation of p53 as confirmed by both Western blot analysis and immunoprecipitation analysis with anti-p53 antibody. Coimmunoprecipitation experiments revealed that the AAV Rep78 is physically bound to p53 in vivo. Furthermore, the binding of purified p53 to the AAV Rep78 affinity column confirms their interaction. These results document for the first time that the antiproliferative effects of AAV against adenovirus are mediated, at least in part, by the interaction of AAV Rep78 with p53.

Tensile properties of articular cartilage are altered by meniscectomy in a canine model of osteoarthritis

Loss of or damage to the meniscus alters the pattern of loading in the knee joint and frequently leads to cartilage degeneration and osteoarthritis. The mechanical properties of articular cartilage have been shown to reflect the extent of cartilage degeneration in human osteoarthritis and in experimental models of joint disease, but there is little experimental data documenting changes in cartilage mechanics following meniscectomy. We hypothesized that the tensile properties of the surface zone of articular cartilage are altered following total medial meniscectomy. Twelve mongrel dogs underwent complete resection of the medial meniscus in the right knee, and the femoral cartilage was studied 12 weeks after the operation. We performed uniaxial, tensile stress-relaxation tests to determine the equilibrium tensile modulus of surface-zone cartilage. Water and glycosaminoglycan content were also measured at site-matched locations. The tensile moduli of the cartilage decreased significantly following meniscectomy. The linear region modulus decreased by 40%, from 25.5 +/- 7.7 to 15.3 +/- 7.2 MPa. There was a weak (r = -0.45), but significant, correlation between the linear region modulus and the gross morphological grade for cartilage damage. Water and glycosaminoglycan content did not change following meniscectomy. Composition was not correlated with mechanical properties or morphological grade, suggesting that cartilage structure may play a more important role than composition in determining the mechanical properties. The observed decrease in cartilage material properties provides a quantitative measure of the loss of cartilage function following meniscectomy and reflects a pattern of change that is consistent with damage to the collagen-proteoglycan solid network.

Improvement of fetal cell recovery from maternal blood: suitable density gradient for FACS separation

OBJECTIVE

To improve the recovery of fetal nucleated erythrocytes (NRBCs) from maternal blood for noninvasive prenatal genetic diagnosis.

METHODS

Blood samples were obtained from 10 women at 8-22 weeks of gestation. Samples were split and mononuclear cells were isolated using 1.083 and 1.090 g/ml of Percoll solution. Flow sorting with antibody to fetal hemoglobin and fluorescence in situ hybridization (FISH) analysis were used to evaluate the number of fetal cells recovered.

RESULTS

In samples separated with the 1.090 density gradient, the yield of true gamma-hemoglobin-positive cells (median 21.0, range 2.2-303.8) was 1.9 times higher than that in the 1.083 density (median 11.1, range 1.1-87.5), although it took 2. 1-fold longer time to flow sort the gamma-hemoglobin-positive cells. In 7 out of 10 cases, the number of gamma-hemoglobin-positive cells recovered from the 1.090 density gradient was 3 times or greater than that from 1.083 gradient. After FISH analysis, we detected a median of 13.3 (range 2.2-98.8) fetal NRBCs per 10-ml maternal blood in the 1.090 density gradient, whereas a median of 11.0 fetal NRBCs were detected in the 1.083 gradient (range 1.1-35.0). The number of fetal NRBCs in the 1.090 density was significantly higher than that in the 1.083.

CONCLUSION

Increased Percoll density results in improved fetal cell recovery in fresh posttermination maternal samples. The increased yield of fetal cells using this gradient may permit better noninvasive detection of fetal chromosome as well as DNA abnormalities in maternal blood.

Specialized surface protrusions of invasive cells, invadopodia and lamellipodia, have differential MT1-MMP, MMP-2, and TIMP-2 localization

Surface protrusions, invadopodia, and analogous lamellipodia at the leading edge of an invasive cell, which make contact with the underlying extracellular matrix (ECM), are the main motor for cellular locomotion and invasion. Previous studies have demonstrated that invadopodia, but not lamellipodia, are sites of ECM degradation on the cell surface. Such degradative activity is in part due to the localization of latent matrix metalloproteinase-2 (MMP-2) and membrane type-1 MMP (MT1-MMP) to invadopodia, where MMP activation occurs. Although lamellipodia exhibit similar structure and mobility to invadopodia, lamellipodia, by virtue of their location at the cellular periphery, are readily accessible to the soluble tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and blood-borne inhibitors. We show here that TIMP-2 co-localizes with MT1-MMP and MMP-2 at lamellipodia but not with that of invadopodia. Thus, the MMP-TIMP localization at lamellipodia may be a key mechanism for the regulation of MMP activation on the cell surface, which in turn governs expression of the cell-invasive phenotype.

The tyrosine kinase c-Abl regulates p73 in apoptotic response to cisplatin-induced DNA damage

Cancer chemotherapeutic agents such as cisplatin exert their cytotoxic effect by inducing DNA damage and activating programmed cell death (apoptosis). The tumour-suppressor protein p53 is an important activator of apoptosis. Although p53-deficient cancer cells are less responsive to chemotherapy, their resistance is not complete, which suggests that other apoptotic pathways may exist. A p53-related gene, p73, which encodes several proteins as a result of alternative splicing, can also induce apoptosis. Here we show that the amount of p73 protein in the cell is increased by cisplatin. This induction of p73 is not seen in cells unable to carry out mismatch repair and in which the nuclear enzyme c-Abl tyrosine kinase is not activated by cisplatin. The half-life of p73 is prolonged by cisplatin and by co-expression with c-Abl tyrosine kinase; the apoptosis-inducing function of p73 is also enhanced by the c-Abl kinase. Mouse embryo fibroblasts deficient in mismatch repair or in c-Abl do not upregulate p73 and are more resistant to killing by cisplatin. Our results indicate that c-Abl and p73 are components of a mismatch-repair-dependent apoptosis pathway which contributes to cisplatin-induced cytotoxicity.

Population-based study of the incidence of Shigella diarrhea and causative serotypes in Santiago, Chile

BACKGROUND

Shigella is an important cause of diarrheal disease in children in developing countries. The increasing prevalence of antibiotic-resistant strains has stimulated interest in the use of multivalent Shigella vaccines. Because Shigella vaccines under development are based on eliciting immunity to O antigens, monitoring the distribution of serotypes in defined target populations is critical. We initiated health center-based surveillance in a poor semirural community in Colina, Santiago (7489 children <60 months of age) to determine the age-specific incidence of Shigella disease and the responsible serotypes.

FINDINGS

Surveillance was maintained at the 2 health centers during warm seasons (November 1 through April 30) for 4 successive years (1994 to 1998). Shigella was recovered from 54 of 243 cases of dysentery (22%) and from 215 of 3966 cases of nondysenteric diarrhea (5.4%) (P < 0.001). The peak mean annual incidence of shigellosis occurred among children 12 to 47 months of age (9.0 to 12.6 cases/10(3) children), although the incidence in infants (5.2/10(3)) and children 48 to 59 months of age (6.2/10(3)) was also substantial. During the 1995 through 1996 season, an age-matched healthy control was cultured for every child <60 months of age with diarrhea. Shigella isolation from cases (34 of 576, 5.9%) was >8-fold higher than controls (4 of 576, 0.7%) (P < 0.01). Four serotypes, Shigella sonnei (45%), Shigella flexneri 2b (19%), S. flexneri 2a (14%) and S. flexneri 6 (11%), accounted for 89% of all cases.

INTERPRETATION

Shigella remains an important pediatric pathogen in Santiago. The serotype distribution from Colina, which closely resembles data from a population-based surveillance study in Santiago in the mid-1980s, demonstrates a remarkable degree of serotype stability in Santiago during a 15-year period.