Structural basis for selectivity of a small molecule, S1-binding, submicromolar inhibitor of urokinase-type plasminogen activator

BACKGROUND

Urokinase-type plasminogen activator (uPA) is a protease associated with tumor metastasis and invasion. Inhibitors of uPA may have potential as drugs for prostate, breast and other cancers. Therapeutically useful inhibitors must be selective for uPA and not appreciably inhibit the related, and structurally and functionally similar enzyme, tissue-type plasminogen activator (tPA), involved in the vital blood-clotting cascade.

RESULTS

We produced mutagenically deglycosylated low molecular weight uPA and determined the crystal structure of its complex with 4-iodobenzo[b]thiophene 2-carboxamidine (K(i) = 0.21 +/- 0.02 microM). To probe the structural determinants of the affinity and selectivity of this inhibitor for uPA we also determined the structures of its trypsin and thrombin complexes, of apo-trypsin, apo-thrombin and apo-factor Xa, and of uPA, trypsin and thrombin bound by compounds that are less effective uPA inhibitors, benzo[b]thiophene-2-carboxamidine, thieno[2,3-b]-pyridine-2-carboxamidine and benzamidine. The K(i) values of each inhibitor toward uPA, tPA, trypsin, tryptase, thrombin and factor Xa were determined and compared. One selectivity determinant of the benzo[b]thiophene-2-carboxamidines for uPA involves a hydrogen bond at the S1 site to Ogamma(Ser190) that is absent in the Ala190 proteases, tPA, thrombin and factor Xa. Other subtle differences in the architecture of the S1 site also influence inhibitor affinity and enzyme-bound structure.

CONCLUSIONS

Subtle structural differences in the S1 site of uPA compared with that of related proteases, which result in part from the presence of a serine residue at position 190, account for the selectivity of small thiophene-2-carboxamidines for uPA, and afford a framework for structure-based design of small, potent, selective uPA inhibitors.

Microdochectomy for single-duct nipple discharge

INTRODUCTION

Isolated single-duct nipple discharge is worrying and poses a surgical dilemma. Factors predicting malignancy are controversial.

MATERIALS AND METHODS

Retrospective review of 92 consecutive microdochectomies for single-duct nipple discharge in a tertiary referral centre over 8 years.

RESULTS

The commonest causes were ductal papilloma (52%) and fibrocystic diseases of the breast (21%). Five (5%) patients had breast carcinoma, of whom only 1 had an invasive component. The median age of these patients was 43 years (range 26 to 72 years) which was similar to median age of the whole cohort. Sixty-seven (73%) patients presented with blood-stained nipple discharge. The 5 patients with breast carcinoma had blood-stained discharge. Mammography was abnormal in 1 out of 4 patients in the carcinoma group.

CONCLUSIONS

The incidence of breast carcinoma in patients presenting with isolated single-duct nipple discharge was low (5%) among Singaporean women. There was no reliable predictors of malignancy, though all patients with carcinoma presented with blood-stained discharge. Microdochectomy still remains an effective treatment for nipple discharge both for cure and diagnosis.

Differential response to low-fat diet between low and normal HDL-cholesterol subjects

Heart attacks frequently occur in normolipidemic subjects with low concentration of high density lipoproteins (</=35 mg/dL). A low-fat diet is generally recommended to patients with coronary heart disease. A low-fat diet decreases both low density (LDL) and high density lipoproteins (HDL). We have shown that on an Average American Diet, subjects with different HDL-cholesterol (HDL-C) levels have different HDL subpopulation profiles. In low HDL-C subjects (</=35 mg/dL), the apoA-I-only subpopulation alpha(1) is significantly decreased compared to individuals with normal HDL-C levels (>35 mg/dL). We hypothesized that as subjects with low HDL-C already have low HDL concentrations, the major decrease of HDL-C will occur in subjects with normal HDL-C when a low-fat diet is consumed. Normolipidemic male subjects consumed three diets differing in total fat and saturated fat composition (AAD: 37%, Step-1: 28%, Step-2: 24% total fat) for 6 weeks in a three-period double-blind randomized crossover design. Plasma lipids and apolipoproteins were determined and changes in distribution of HDL subpopulations were evaluated. As a result of a low-fat diet, low HDL-C individuals slightly decreased their HDL-C, but substantially decreased their LDL-C resulting in a significant improvement in the LDL-C/HDL-C ratio. However, subjects with normal HDL-C levels decreased both their LDL-C and HDL-C resulting in an unchanged LDL-C/HDL-C ratio. We also observed significant differences in response to low-fat diets in HDL-C and alpha(1) concentrations between low and normal HDL-C subjects. In the normal HDL-C group, consumption of a low-fat diet also resulted in redistribution of apoA-I-containing HDL subpopulations, indicated by a decrease in the large apoA-I-only alpha(1) subpopulation. These data demonstrate that male subjects with low HDL-C respond to a low-fat diet differently than individuals with normal HDL-C.

FIMM, a database of functional molecular immunology

FIMM database (http://sdmc.krdl.org.sg:8080/fimm ) contains data relevant to functional molecular immunology, focusing on cellular immunology. It contains fully referenced data on protein antigens, major histocompatibility complex (MHC) molecules, MHC-associated peptides and relevant disease associations. FIMM has a set of search tools for extraction of information and results are presented as lists or as reports.

Assessing the in vitro cell based ocular compatibility of contact lens materials

A series of in vitro assays for determining the biocompatibility of ocular biomaterials have been developed and used to assess the differences in performance of omafilcon A, etafilcon A and nelfilcon A contact lens materials. The assays assessed bacterial attachment, macrophage adhesion, granulocyte adhesion and activation, epithelial cell adhesion and corneal cell contact damage. Overall, omafilcon A was found to be more biocompatible than the other materials although there was no significant difference between the epithelial cell adhesion and granulocyte adhesion and activation on any of the hydrogels. Etailcon A performed less well compared to nelfilcon A and omafilcon A with respect macrophage adhesion and bacterial adhesion. The results indicate that these biological assays can be successfully applied for the testing of contact lens materials and may be particularly useful in the in vitro screening of new extended wear contact lens materials where cell adhesion and activation may have a greater influence on clinical performance.

Development of multi-species consortia biofilms of oral bacteria as an enamel and root caries model system

The aim was to establish defined-species consortium plaque biofilms to investigate enamel and root caries in an artificial mouth. Strains of the putative enamel and root caries pathogens, Streptococcus mutans, Strep. sobrinus, Actinomyces naeslundii and Lactobacillus rhamnosus, were screened in batch culture for potential cariogenic properties: a low terminal pH, ability to aggregate, and catabolic diversity. The strains selected were grown as monoculture biofilms and as consortium plaque biofilms in a multiplaque artificial mouth. The biofilms were supplied with a constant flow of a simulated oral fluid and were given periodic sucrose (and in some instances glucose) to simulate meals. All the bacteria except L. rhamnosus formed large, monospecies biofilms with resting pH in the range 5.3-5.8. The consortia biofilms were larger and had a resting pH of 4.9-5.3. The consortia biofilms supplied with 8-hourly carbohydrate comprised mainly 'mutans' streptococci (58, SD 5.5%) and L. rhamnosus (42, SD 5.7%). A. naeslundii characteristically was absent or present in a low percentage (up to 4% colony-forming units). All biofilms demineralized polished bovine enamel and dentine blocks, as assessed by microradiography and enamel-surface microhardness measurement. The consortia also demineralized intact enamel and tooth roots; they were more cariogenic to enamel than any of the monoculture biofilms, as measured by enamel-surface softening, but variation in lesion depth was proportional to biofilm wet weight irrespective of acidogen composition (r = 0.93, p < 0.05). Enamel lesions had a well-mineralized intact surface and a zone of subsurface demineralization, typical of early natural lesions. Dentine and root lesions showed extensive demineralization but lacked a pronounced surface mineralized zone. Substitution of glucose for sucrose had no effect on the cariogenicity of the consortium to bovine enamel or human roots and had no major effect on the plaque composition. Continuously supplied fluoride (19 parts/10(6)) resulted in a substantially reduced enamel surface softening and subsurface demineralization of intact roots. It was concluded that consortia biofilms of selected caries pathogens generate realistic caries lesions in all tooth hard tissues under controlled growth conditions in the artificial mouth. This in vitro caries experimental model may prove useful for the study of interrelations between the plaque biofilm, tooth tissues and the oral environment, and for the development of procedures to modify the course of caries development.

Needle-tract implantation from hepatocellular cancer: is needle biopsy of the liver always necessary?

Percutaneous needle biopsies are frequently used to evaluate focal lesions of the liver. Needle-tract implantation of hepatocellular cancer has been described in case reports, but the true risk for this problem has not been clearly defined. We retrospectively reviewed 91 cases of hepatocellular cancer during a 4-year period from 1994 to 1997. Data on diagnostic studies, therapy, and outcome were noted. Of 91 patients with hepatocellular cancer, 59 patients underwent percutaneous needle biopsy as part of their diagnostic workup for a liver mass. Three patients (5.1%) were identified with needle-tract implantation of tumor. Two patients required en bloc chest wall resections for implantation of hepatocellular cancer in the soft tissues and rib area. The third patient, who also received percutaneous ethanol injection of his tumor, required a thoracotomy and lung resection for implanted hepatocellular cancer. Percutaneous needle biopsy of suspicious hepatic lesions should not be performed indiscriminately because there is a significant risk for needle-tract implantation. These biopsies should be reserved for those lesions in which no definitive surgical intervention is planned and pathological confirmation is necessary for a nonsurgical therapy.

Cyclic 3-deaza-adenosine diphosphoribose: a potent and stable analog of cyclic ADP-ribose

Cyclic 3-deaza-adenosine diphosphoribose (3-deaza-cADPR), an analog of cyclic adenosine diphosphoribose (cADPR) was synthesized. 3-deaza-cADPR differs from cADPR by only the substitution of carbon for nitrogen at the 3-position of the purine ring. Similar to cADPR, the analog has potent calcium releasing activity in sea urchin egg homogenates and was able to induce calcium release at concentrations as low as 0.3 nM. The EC(50) value for 3-deaza-cADPR-induced calcium release was 1 nM, which is about 70 times more potent than cADPR. The properties of calcium release induced by 3-deaza-cADPR in all other respects were similar to those of cADPR. Thus, 3-deaza-cADPR and cADPR were capable of cross-desensitizing each other and their calcium releasing activities were potentiated by Sr(2+) as well as caffeine. 8-amino-cADPR, a selective antagonist of cADPR, was also able to inhibit 3-deaza-cADPR induced calcium release. Taken together, these data suggest that 3-deaza-cADPR releases calcium through the same mechanism as cADPR. 3-deaza-cADPR was found to be resistant to both heat and enzymatic hydrolysis. Only 15% of 3-deaza-cADPR was destroyed after boiling this compound for 2 h. No loss of 3-deaza-cADPR was observed when treated with CD38 under conditions where cADPR was completely hydrolyzed. Thus, 3-deaza-cADPR is a potent and stable analog of cADPR. These properties should make 3-deaza-cADPR a useful probe in studies focused on the mechanism of cADPR action.

Kleisli: a new tool for data integration in biology

One of the central problems in bioinformatics is data retrieval and integration. The existing biological databases are geographically distributed across the Internet, complex and heterogeneous in data types and data structures, and constantly changing. With the current rapid growth of biomedical data, the challenge is how large volumes of data retrieved from multiple databases can be transformed and integrated automatically and flexibly. This article describes a powerful new tool, the Kleisli system, for complex queries across multiple databases and data integration.

Integration of bioInformatics tools at the National University of Singapore (NUS)

In the past decade "Big Science" such as the Genome Project has generated an enormous amount of data in the life sciences. Concurrently, the synergy of this project with existing research has quickened the pace of biological discovery. But the major drawback that is beginning to be felt worldwide is the primitive level of organisation in the data accumulated. Without a proper framework or knowledge scaffold to hang and interconnect the various bits of data and information, the national knowledge-to-data ratio is declining rapidly. We are trying to serve a solution to this enigma by providing a World Wide Web (WWW) interface to Biosoftware and at the same time have come up with a database integration tool that can query heterogeneous, geographically scattered and disparate databases simultaneously. In this report we will talk about BioInformatics in general with specific reference to BioInformatics Centre (BIC) at the National University of Singapore.

Divalent cations and the electrostatic potential around DNA: Monte Carlo and Poisson-Boltzmann calculations

The predictions of counterion condensation theory for divalent ions were tested by comparison with the results of Monte Carlo calculations on an all-atom model of DNA. Monovalent-divalent competition at the polyelectrolyte surface was investigated by varying the partial molar volume of divalent ions. To assess the viability of using Poisson-Boltzmann (PB) calculations for determining divalent ion concentrations at DNA surfaces, Monte Carlo (MC) calculations were compared with PB calculations using different models of the dielectric continuum. It was determined that, while standard PB calculations of divalent ion surface densities are about 25-30% below those predicted by MC techniques, and somewhat larger than errors previously determined for monovalent ions, errors due to the use of the mean-field approximation of PB theory are smaller than those arising from common assumptions regarding the dielectric continuum.

Analysis of cholinesterase inactivation and reactivation by systematic structural modification and enantiomeric selectivity

We show here with a congeneric series of Rp- and Sp-alkoxymethyl phosphonothiolates of known absolute stereochemistry that chiral selectivity in their reaction with acetylcholinesterase can be described in terms of discrete orientational and steric requirements. Stereoselectivity depends on acyl pocket dimensions, which govern leaving group orientation and a productive association of the phosphonyl oxygen in the oxyanion hole. Overall geometry is consistent with a pentavalent intermediate where the attacking serine and leaving group are at apical positions. Oxime reactivation of the phosphonylated enzyme occurs through a similar associative intermediate presumably forming an oxime phosphonate. The oximes of differing structure show distinct angles of attacking the phosphate where the attack angles and access to the phosphorus are constrained in the sterically impacted gorge. Hence, efficacy of oxime reactivation is dependent on both oxime and conjugated phosphonate structures.

Human endogenous retrovirus with a high genomic sequence homology with IDDMK(1,2)22 is not specific for Type I (insulin-dependent) diabetic patients but ubiquitous

AIMS/HYPOTHESIS

It has been reported recently that a novel human endogenous retroviral gene, insulin-dependent diabetes mellitus (IDDM)K(1,2)22, was expressed in the plasma of Type I diabetic patients but not in that of nondiabetic control subjects. This investigation was initiated to determine the specificity of the selective expression of IDDMK(1,2)22 in diabetic patients.

METHODS

We isolated the total RNA from the plasma and lymphocytes of 13 new onset Type I diabetic patients and 10 normal control subjects and amplified it by reverse transcriptase polymerase chain reaction. We then determined the presence of IDDMK(1,2)22 with a specific primer set, U3/R-poly(A), used in a recent report and the 5 'SAg/3 'SAg primer set recognizing the putative superantigen encoding the region of the IDDMK(1,2)22 envelope (env) gene. In addition, we carried out nested PCR of the U3/R-poly(A) polymerase chain reaction product using U3N/R primers.

RESULTS

We found no difference in the presence of the polymerase chain reaction products between diabetic patients and all nondiabetic subjects tested. Sequencing of the U3/R-poly(A) polymerase chain reaction products showed that the exact sequence of IDDMK(1,2)22 was not present in any of the samples tested, neither in the plasma of diabetic patients nor in that of nondiabetic control subjects. Endogenous retroviral sequences with 90-93% sequence homology to IDDMK(1,2)22 were, however, equally present in both the diabetic and nondiabetic subjects.

CONCLUSION/INTERPRETATION

We conclude that a human endogenous retroviral gene with high sequence homology with IDDMK(1,2)22 is not specific for diabetic patients but, rather, is ubiquitous.

[Effects of 17 beta-estradiol on intracellular free calcium, inositol-1,4,5-trisphophate and calmodulin in human osteoblast-like osteosarcoma cell line TE85]

OBJECTIVE

To study the effects of 17 beta-estradiol (E2) on intracellular free calcium ([Ca2+]i), inositol-1,4,5-trisphophate (IP3) and calmodulin (CaM) in human osteoblast-like cell line TE85.

METHODS

Using Fluo-3/AM as fluorescent indicator, the [Ca2+]i was measured by laser confocal microscopy system. The IP3 content was determined by anion-exchange chromatography. CaM content was detected by a high sensitive assay based on stimulation of Ca(2+)-dependent phosphodiesterase activity.

RESULTS

E2 at dose of 0.1 and 1.0 nmol/L increased fluorescent level by 4.7 and 6.1 times. Pretreatment with thapsigargin (100 nmol/L), the E2 caused only 1.5 times elevation in fluorescence. E2 induced a concommitant bi-peak increase in IP3 content. At the presence of E2(1.0 nmol/L), the CaM content increased by 85.2%. Tamoxifen did not affect the effect of E2 on [Ca2+]i, IP3 and CaM content. But, the inhibitor of phospholipase C (neomycin) and pertusis toxin depressed them partly or completely.

CONCLUSIONS

E2 regulate bone cells function by way of Ca2+/CaM activation.

A novel treatment of patients with chronic hepatitis C

OBJECTIVES

Interferon alpha-2b therapy for Chronic Hepatitis C patients has been unsatisfactory. Recombinant Granulocyte Macrophage Colony-Stimulating Factor has been shown to have anti-viral effects in vivo and in vitro via cytokines release. Recently its effects on chronic hepatitis B and possibly chronic hepatitis C were reported. We, decided to conduct a pilot study to evaluate the anti-viral effects of recombinant human GM-CSF mono-therapy in patients with chronic hepatitis C and to assess its side effects.

METHODS

A total of 10 patients (male/female: 5/5) (age: 34-60, mean: 45) seen in our center between 2/95 to 2/96 were randomly selected to receive recombinant human Granulocyte Macrophage Colony-Stimulating-Factor at 125 ug/m2 subcutaneously daily for two weeks followed by three times weekly for another 8 weeks. Biochemical (ALT) and viral (HCV-RNA) responses were measured prior to treatment and at weeks four and eight. Side effects were recorded.

RESULTS

Six out of the ten patients treated had significant viral reduction but none became negative. Eight out the ten patients treated showed biochemical improvement and three out of the eight had normalized liver enzymes. Age, sex, stage of the disease did not influence the response but there seems to be a tendency for patients with higher pre-treatment viral level to respond virally. Side effects are minimal and well-tolerated.

CONCLUSION

Recombinant human Granulocyte Macrophage Colony-Stimulating-Factor in the dose used has anti-viral effects in the majority of the chronic hepatitis C patients studied. Side effects are minimal and well tolerated. Further study with higher doses and longer duration is needed to prove its clinical efficacy in treating patients with chronic hepatitis C.

A differential requirement for the COOH-terminal region of the epidermal growth factor (EGF) receptor in amphiregulin and EGF mitogenic signaling

The epidermal growth factor receptor (EGFR) mediates the actions of a family of bioactive peptides that include epidermal growth factor (EGF) and amphiregulin (AR). Here we have studied AR and EGF mitogenic signaling in EGFR-devoid NR6 fibroblasts that ectopically express either wild type EGFR (WT) or a truncated EGFR that lacks the three major sites of autophosphorylation (c'1000). COOH-terminal truncation of the EGFR significantly impairs the ability of AR to (i) stimulate DNA synthesis, (ii) elicit Elk-1 transactivation, and (iii) generate sustained enzymatic activation of mitogen-activated protein kinase. EGFR truncation had no significant effect on AR binding to receptor but did result in defective GRB2 adaptor function. In contrast, EGFR truncation did not impair EGF mitogenic signaling, and in c'1000 cells EGF was able to stimulate the association of ErbB2 with GRB2 and SHC. Elk-1 transactivation was monitored when either ErbB2 or a truncated dominant-negative ErbB2 mutant (ErbB2-(1-813)) was overexpressed in cells. Overexpression of full-length ErbB2 resulted in a strong constitutive transactivation of Elk-1 in c'1000 but only slightly stimulated Elk-1 in WT or parental NR6 cells. Conversely, overexpression of ErbB2-(1-813) inhibited EGF-stimulated Elk-1 transactivation in c'1000 but not in WT cells. Thus, the cytoplasmic tail of the EGFR plays a critical role in AR mitogenic signaling but is dispensable for EGF, since EGF-activated truncated EGFRs can signal through ErbB2.

Children who are cruel to animals: a revisit

OBJECTIVE

There is a paucity of research regarding children who are cruel to animals (CTA). Previous studies have suggested that being CTA is linked with recurrent aggression in adulthood. In this report, children with persistent conduct problems who are CTA are examined.

METHOD

A clinic-referred sample of 141 children and a community sample of 36 children between the ages of 5-12 were assessed using a test battery of questionnaires for parents, teachers and the child on mental health symptoms, self-perception, demographics and psychosocial factors. Forty of the clinic-referred children and one of the community group were rated by their parents as sometimes or definitely cruel to animals. The CTA, non-CTA and community samples were compared.

RESULTS

The CTA group had more conduct symptoms compared with the non-CTA group. However, the older CTA group unexpectedly reported a higher self-esteem compared with the non-CTA group. There was no significant difference between the two clinic-referred groups in gender, attention deficit hyperactivity disorder and internalising symptoms, and psychosocial factors.

CONCLUSION

Being CTA is possibly a marker of a subgroup of conduct disorder which has a poor prognosis.

Domiciliary oxygen and smoking: an explosive combination

Home oxygen therapy has been used to provide symptomatic relief of breathlessness for more than 20 yr. Continuous low-flow oxygen can improve exercise tolerance and decrease pulmonary hypertension in patients suffering from chronic obstructive airway disease. The majority of these patients have been long-time smokers. Despite routine warnings about potential dangers, a considerable number of patients will continue to smoke whilst on oxygen. The incidence of burn injuries related to this practice is not known. Reports of such incidents are, however, very rare. Twenty-one patients who sustained head and neck burn injuries secondary to cigarette related ignition of their oxygen delivery system were admitted to our burn unit over a 7-yr period (1990-1997). All patients (mean age 60.4 yr) had been informed about the associated risks but did not shut off their supplemental oxygen system during smoking. The mean size of their burn injuries was 2% of the total body surface, mainly affecting the face, ears, and neck. The average duration of the hospital stay was 3.6 days. Two patients required split-thickness skin grafting. Whether chronically ill patients on domiciliary oxygen who continue to smoke covertly are amenable to medical advice to abandon this habit is questionable. A more aggressive education about the explosive nature of their activity should help to prevent them from using tobacco and oxygen at the same time.

From sequence to structure to literature: the protocol approach to bioinformation

Until the recent advent of high-throughput experimental data-acquisition in biology, the computational analysis of the biological data was predominantly on an ad hoc basis--i.e., the application of a given piece of software on the biological data depended on the need of the moment. This "functional approach" often resulted in piecemeal computational analysis with large amount of intervening "dead-time". The present high-throughput availability of experimental biological data requires a more streamlined and integrated "protocol approach". In this work, we illustrate such a user-friendly protocol using a common question frequently faced by a wet-lab bench-biologist--"Now that I have a DNA or protein sequence, what can I do with it using a computer?" As phrased, this question is steeped in the functional approach. In contrast, the protocol approach would re-phrase the same question as "Now that I have a DNA or protein sequence, what can a computer do for me?" Our integrating tool can start with a sequence and build a substantial custom data-warehouse of computationally derived sequence information, structure information and relevant published literature, that is continually updated.

Zf9, a Kruppel-like transcription factor up-regulated in vivo during early hepatic fibrosis

Wound repair in the liver induces altered gene expression in stellate cells (resident mesenchymal cells) in a process known as "activation." A zinc finger transcription factor cDNA, zf9, was cloned from rat stellate cells activated in vivo. Zf9 expression and biosynthesis are increased markedly in activated cells in vivo compared with cells from normal rats ("quiescent" cells). The factor is localized to the nucleus and the perinuclear zone in activated but not quiescent cells. Zf9 mRNA also is expressed widely in nonhepatic adult rat tissues and the fetal liver. The zf9 nucleotide sequence predicts a member of the Kruppel-like family with a unique N-terminal domain rich in serine-proline clusters and leucines. The human zf9 gene maps to chromosome 10P near the telomere. Zf9 binds specifically to a DNA oligonucleotide containing a GC box motif. The N-terminal domain of Zf9 (amino acids 1-201) is transactivating in the chimeric GAL4 hybrid system. In Drosophila schneider cells, full length Zf9 transactivates a reporter construct driven by the SV40 promoter/enhancer, which contains several GC boxes. A physiologic role for Zf9 is suggested by its transactivation of a collagen alpha1(I) promoter reporter. Transactivation of collagen alpha1(I) by Zf9 is context-dependent, occurring strongly in stellate cells, modestly in Hep G2 cells, and not at all in D. schneider cells. Our results suggest that Zf9 may be an important signal in hepatic stellate cell activation after liver injury.

Fixation of the craniofacial skeleton with butyl-2-cyanoacrylate and its effects on histotoxicity and healing

Butyl-2-cyanoacrylate is an easily applied, biocompatible, bioresorbable polymer glue that provides an alternative to conventional rigid fixation techniques. Our aim was to determine if cyanoacrylate fixation of the bone flap in a rabbit craniotomy model provides the healing and strength afforded by plate and screw fixation. We also investigated the inflammatory responses of adjacent tissues including the scalp, cranium, and brain. A unilateral parietal bone flap was elevated in 33 adult New Zealand rabbits. The bone was fixed in position with cyanoacrylate (n = 13), fixed with a microplate and screws (n = 14), or was replaced without fixation (sham-control, n = 6). Normal scar formation and no residual polymer were found in scalp specimens. Neuropathologic analysis identified the presence of residual polymer on the surface of 2 of the 13 rabbit brains. Histopathologic analysis of the bone flap-to-skull interface revealed no difference in the degree but rather in the quality of inflammation and healing between the plate and screw and polymer fixation groups. Microdensitometric analysis of the bone gap revealed nearly equivalent bone density in the cyanoacrylate and plated groups, tending to less density in the sham group (p = 0.11 and 0.09, respectively). An additional study focusing on neurotoxicity was performed in 20 adult rabbits with 3-week and 11-week recovery periods and similarly found the absence of a marked inflammatory response to the polymer. In conclusion, bone healing and soft-tissue inflammation were comparable between cyanoacrylate and plate and screw fixation groups. Although butyl-2-cyanoacrylate glue fixation may provide a reasonable alternative to hardware fixation, further investigations are necessary to identify its ideal utilization.

A real-time algorithm to improve the response time of a clinical multigas analyser

OBJECTIVE

An algorithm to improve the response time of a clinical respiratory multigas analyser is presented.

METHODS

The algorithm involves the application of a second order differential equation to the analyser gas output signals in real-time. The adjusted analyser output signals are compared with those of a quadrupole respiratory mass spectrometer sampling and analysing simultaneously.

RESULTS

Our results show a close correlation between the adjusted clinical gas analyser and the mass spectrometer signals. Lung volumes derived from a non-invasive sinusoidal inert gas forcing technique, in a model test lung, using the adjusted clinical gas analyser and the mass spectrometer signals demonstrated comparable results.

CONCLUSIONS

The algorithm provides an improvement on the relatively slow response times of the clinical gas analyser for breath-by-breath time-dependent applications. The same algorithm can also be applied to other instruments which have slow response times.

Butyl-2-cyanoacrylate fixation of mandibular osteotomies

Butyl-2-cyanoacrylate is an easily applied, bioresorbable, noninfective glue that may provide an alternative to conventional craniofacial fixation techniques. Recent studies have demonstrated that the healing and strength of glue fixation of bone fragments in the craniofacial skeleton is equivalent to that of plate and screw fixation. We sought to determine if this glue could also provide strength and healing in a more stressed environment, that of the mandible. Fourteen New Zealand White rabbits underwent mandibular osteotomies at the angle. The osteotomy was fixed with either a microplate (n = 4) or glue (n = 10). Mandibles were assessed 10 weeks postoperatively and classified according to bone healing, condylar morphology, and dental morphology. Callus and nonunion were more prevalent in the glued group, whereas condylar resorption was similar in both experimental groups. Despite the poor bony healing in the glued group, the teeth did not decay but modified their standard form to meet the demands of the anatomic deformity. Butyl-2-cyanoacrylate does not offer the biomechanical stability afforded by plates and screws in bone subject to large forces.

Characterization of phospholipids in pre-alpha HDL: selective phospholipid efflux with apolipoprotein A-I

Previously, we have shown that lipid-free apoA-I, when incubated with fibroblasts, will produce lipoproteins of pre-alpha mobility (Asztalos, B. F., et al. 1997. Arterioscler. Thromb. Vasc. Biol. 17: 1630-1636). In order to understand the nature of these pre-alpha particles, we further characterized their lipid content. The pre-alpha particles are high density lipoproteins, having a median density of 1.08 g/ml. They have a surface charge of -18.45 mV. The phospholipid composition of these particles showed that they have 4% each of phosphatidyl ethanolamine and inositol; 69% phosphatidyl choline and 18% sphingomyelin. This phospholipid composition is different from those of plasma HDL (81% phosphatidyl choline, 13% sphingomyelin), plasma membrane on the fibroblasts, and whole fibroblast phospholipid. To demonstrate that the pre-alpha mobility resides in the lipids, lipids from pre-alpha lipoproteins were reconstituted with lipid-free apoA-I. The resultant particles retained their pre-alpha mobility. We conclude that apoA-I may react with specific regions of plasma membrane to acquire this unusual lipid composition and that pre-alpha mobility is caused in part by the unusual phospholipid composition.

Coordinated induction of VEGF receptors in mesenchymal cell types during rat hepatic wound healing

Homology PCR has been used to identify receptor tyrosine kinases (RTKs) expressed during activation of rat hepatic stellate cells, the key fibrogenic mesenchymal element in the liver. Partial cDNAs encoding several RTKs were cloned from stellate cells activated in vivo, including those of Flt-1, Flk-1, c-met, PDGFR, and Tyro10/DDR2. RNAse protection from cells activated in vivo demonstrated biphasic induction of flt-1 and flk-1 mRNAs, receptors for vascular endothelial growth factor (VEGF). Culture-activation of stellate cells was associated with increased [125I]VEGF binding and Flt-1 and Flk-1 receptor protein. Induction of VEGF binding sites correlated with an 2.5-fold increase in DNA synthesis in response to VEGF, but only if cells were activated by growth on collagen 1, whereas cells maintained in a quiescent state on a basement membrane-like substratum (EHS matrix) were nonproliferative. In both stellate and endothelial cells VEGF-induced mitogenesis was augmented by co-incubation with basic fibroblast growth factor (bFGF), a cytokine with known synergy with VEGF. These findings suggest that the cellular targets of VEGF in liver may not be confined to sinusoidal endothelial cells, and that VEGF responses reflect combined effects on both hepatic stellate cells and sinusoidal endothelium.

A common requirement for the catalytic activity and both SH2 domains of SHP-2 in mitogen-activated protein (MAP) kinase activation by the ErbB family of receptors. A specific role for SHP-2 in map, but not c-Jun amino-terminal kinase activation

The ErbB family of receptors, which include the epidermal growth factor receptor (EGFR), ErbB2, ErbB3, and ErbB4 mediate the actions of a family of bioactive polypeptides. EGF signals through EGFR, whereas heregulin (HRG) signaling is initiated through binding to either ErbB3 or ErbB4. In this report we studied the role of protein-tyrosine phosphatase SHP-2 in ErbB-mediated activation of mitogen-activated protein kinase (MAPK) by overexpressing SHP-2 mutants in COS-7 cells. We demonstrate that enzymatic activity and both NH2- and COOH-terminal SH2 domains of SHP-2 are required for EGF-induced MAPK activation, but not for c-Jun amino-terminal kinase stimulation or MAPK activation which occurred in response to myristoylated son of sevenless, activated Ras, or phorbol ester. Dominant-negative forms of SHP-2 had no effect on EGF-stimulated interaction of GRB2 with EGFR or SHC, nor did they influence phosphorylation of SHC and SHC/EGFR association. The same mutant SHP-2 structures that inhibited EGF-mediated stimulation of MAPK also blocked HRG alpha/beta-induced MAPK activation. EGF or HRG beta caused SHP-2 SH2 domains to engage multiple phosphotyrosine proteins, and mutation of either domain disrupted these associations. These results demonstrate that SHP-2 performs a common and essential function(s) in ligand-stimulated MAPK activation by the ErbB family of receptors.

Strategies of information disclosure to Chinese cancer patients in an Asian community

There is little information available on strategies of information disclosure used by doctors in the care of patients with cancer. This report focuses on the style of disclosure used by doctors when giving diagnostic and prognostic information to patients with cancer. Among 46% of 133 surgeons and radiotherapists interviewed, disclosure of diagnosis involved a sudden approach (information given outright at one sitting). Less commonly used (19%) was a gradual disclosure style. Of the remainder who disclosed, more than half did so through the family or left it to the family to tell the patient. Doctors' specialty and patients' requests for prognostic information dictated disclosure style most frequently. Single people were more likely to have information disclosed to their families than were married people. While anecdotal accounts indicate negative reactions on the part of patients are a major reason for withholding such information, different disclosure style had little effect on doctors' reports of patient reactions to the bad news. Doctors perceived 25% of patients appeared to react 'with depression' but the remaining 75% appeared 'calm'. These results suggest patients are more likely to be told bad news suddenly, and that doctors do not perceive that this impacts too negatively on patients. The high levels of reported preference for information about cancer in Hong Kong (Fielding and Hung, 1996) conflict with actual prevalence patterns. It seems that commonly cited anecdotal reasons for withholding information from cancer patients in Hong Kong are not sustained by the data produced in these studies.

Plaque mineralisation in vitro

Dental calculus is plaque mineralised by deposition of calcium and phosphate resulting from interactions between the oral microbial plaque flora and components of oral fluids. An artificial-mouth microcosm dental plaque culture system has been developed to study aspects of plaque mineralisation, including pH control. Five plaques were grown from saliva under simulated oral conditions in a mucin-containing medium, and sucrose was applied to mimic meals. The plaques were mineralised with a urea-based, calcium-phosphate-monofluorophosphate-urea (CPMU) mineralising solution. Alkaline pH oscillations were generated by the plaques in response to CPMU applications, and an acidic oscillation followed sucrose applications. Plaque mineralisation by the CPMU procedure was almost totally dependent on the urea present in the mineralising solution, but total mineralisation also increased as the resting pH increased as a result of urea in the medium. Following four CPMU applications with a sucrose application every 12 hours improved plaque viability and mineralisation. The plaque mineral formed resembled a carbonated hydroxyapatite; other potential calcium phosphate minerals were undetectable except for calcium carbonate. A wide range of mineral deposition patterns in plaque were seen by electron microscopy.

Factors affecting the resting pH of in vitro human microcosm dental plaque and Streptococcus mutans biofilms

The aim was to examine factors that potentially control the resting pH, defined as the pH unaffected by meals, of microcosm dental plaques and Streptococcus mutans biofilms under standard conditions, and to examine the effect of supplying urea at concentrations found intraorally. Microcosm plaques were cultured from plaque bacteria-enriched saliva in an 'artificial mouth' with a continuous supply of a medium including 0.25% mucin [Basal Medium Mucin, (BMM), 3.6 ml/hr per plaque] and a periodic supply of sucrose. The steady-state resting pH was 6.4 (range +/- 0.1) in BMM containing no urea and supplied at the standard flowrate. This is a robust property of the ecosystem. In one experiment with a replicated (n = 9) set of measurements, the resting pH was approx. pH 6.3, 6.4, 6.7 and 7.3 with 0, 1, 5 and 20 mmol/l urea in the BMM. The magnitude of sucrose- and urea-induced pH responses was unaffected by elevating the resting pH to produce parallel pH curves. The sucrose-induced pH curves were analogous to those classically reported by Stephan that showed an association between caries activity and increasingly acidic plaque pH responses to glucose. Stopping the BMM flow caused a pH rise, indicating continuing net alkali generation from BMM components in the absence of a fluid flow. Step. mutans monoculture biofilms had an acidic resting pH of 5.0 to 5.3, which increased to 6.8 following an adventitious superinfection by Bacillus cereus. It was concluded that the resting pH in plaque results from a delicate balance between alkali and acid generation, which is in turn dependent both on the bacterial composition of the plaque and on the supply of substrates and buffers from, and metabolite clearance into, flowing oral fluid. In vivo the resting pH will vary with site-specific changing saliva flows. Urea continuously supplied at concentrations normal for saliva and gingival crevicular fluid can raise the resting pH of microcosm plaque by an amount tat in vivo would probably be significant in reducing dental caries.

Reforming the household registration system: a preliminary glimpse of the blue chop household registration system in Shanghai and Shenzhen

"For decades, the household registration system has functioned as a powerful device in halting rural influxes into Chinese cities. The exigencies of the reform call for reform of the hukou system [China's household registration]. One of the many attempts is the blue chop household registration system. Both Shanghai and Shenzhen have introduced this practice. In addition to promotion of real estate and investment, it creams off those more desirable migrants into the permanent population of the two cities. In view of the present situation of linking welfare provision with household registration status, this selective migration policy seems to be a sensible step forward."

Development of software tools at BioInformatics Centre (BIC) at the National University of Singapore (NUS)

There is burgeoning volume of information and data arising from the rapid research and unprecedented progress in molecular biology. This has been particularly affected by the Human Genome Project which is trying to completely sequence three billion nucleotides of the human genome (1),(1a). Other genome sequencing projects are also contributing substantially to this exponential growth in the number of DNA nucleotides and proteins sequenced. The number of journals, reports and research papers and tools required for the analysis of these sequences has also increased. For this the life sciences today needs tools in information technology and computation to prevent degeneration of this data into an inchoate accretion of unconnected facts and figures. The recently formed BioInformatics Centre (BIC) at the National University of Singapore (NUS) provides access to various commonly used computational tools available over the World Wide Web (WWW)--using a uniform interface and easy access. We have also come up with a new database tool. BioKleisli, which allows you to interact with various geographically scattered, heterogeneous, structurally complex and constantly evolving data sources. This paper summarises the importance of network access and database integration to biomedical research and gives a glimpse of current research conducted at BIC.

Magnetic resonance imaging analysis of lumbar disc changes below scoliosis fusions. A prospective study

STUDY DESIGN

The authors of this prospective study examined the preoperative and 3-year postoperative magnetic resonance images of 14 patients undergoing anterior and posterior fusion and/or posterior fusion only for scoliosis. All magnetic resonance images were ready by two independent neuroradiologists, who were blinded to the purposes of the study, for the presence of disc narrowing, signal decrease on T2, or herniated nucleus pulposus before and after surgery. Particular attention was paid to the disc changes at the level directly below the end vertebral level of the fusion and two levels below the fusion in the lumbosacral spine existing before surgical intervention.

OBJECTIVES

To evaluate the potential for disc degeneration distal to long scoliosis fusions with end fusion levels in the mid to lower lumbar spine.

SUMMARY OF BACKGROUND DATA

The determination of end levels of fusion for contructs presently used to manage adult scoliotic deformity has been evaluated in terms of correction of curvature and late decompensation in coronal and sagittal plane balance after fusion. However, the natural history of the caudal, free-motion segments in terms of degeneration and/or correlation with pain has not yet been addressed.

METHODS

Fourteen patients undergoing scoliosis fusion underwent magnetic resonance imaging before surgery and approximately 3 years after surgery. The scans were reviewed by two independent neuroradiologists who looked at three degenerative indices at the disc below the area of scoliosis fusion. The authors analyzed rates of change of the three degenerative indices in the pre- and postoperative magnetic resonance images and created associations between the observed changes on the magnetic resonance images and the clinical outcomes of pain, the presence or absence of solid fusion, and the need for repeat surgery.

RESULTS

Estimates of the rates of change of the three degenerative indices one or two levels below the fusion were as follow: the chance of disc narrowing, .2-34%; the chance of a decreasing signal on T2, 5-54%, with a 23% incidence among this group; and the chance of herniated nucleus pulposus, 0-34%. There was a significant correlation between the presence of back and/or leg pain and the signal decrease one level below the fusion (P = .04).

CONCLUSIONS

If these results are corroborated in a larger sample size, surgeons who manage deformity may have to consider altering fusion levels at the time of fusion based on magnetic resonance imaging predictors. The present data may help to inform patients about the risk of developing junctional degenerative changes and potential symptoms from these changes below scoliosis fusions.

Normolipidemic subjects with low HDL cholesterol levels have altered HDL subpopulations

Epidemiological studies have established that plasma concentration of HDL is inversely correlated with the risk of coronary heart disease, even in the absence of increased LDL cholesterol levels. We postulate that specific HDL subpopulations may be responsible for antiatherogenic properties of HDL. HDL subpopulations were quantitated by two-dimensional gel electrophoresis in 79 normolipidemic healthy male subjects. To eliminate the influence of diet, volunteers consumed an average American diet for 6 weeks. After the diet period, subjects were stratified according to their HDL cholesterol (HDL-C) levels to low HDL-C < 0.91 mmol/L (< 35 mg/dL), medium > 0.91 < 1.30 mmol/L (> 35 < 50 mg/dL), and high > or = 1.30 mmol/L (> or = 50 mg/dL) groups. Plasma triglycerides and insulin levels were in the normal range, but subjects with low HDL-C levels had higher concentrations of plasma triglycerides and insulin than subjects with medium or high HDL-C concentrations. The absolute concentration (mg/dL) of apoA-I in the largest alpha-migrating HDL subpopulation (alpha 1) was (P < .01) lower in the low HDL-C subjects compared with the medium and high HDL-C groups. The relative concentration (percent distribution) of apoA-I was decreased (P < .01) in alpha 1 and increased (P < .01) in alpha 3 subpopulations. A positive correlation between HDL-C and alpha 1 (P < .001) and a negative correlation between HDL-C and alpha 3 were observed. The inverse correlation of apoA-I distribution (relative concentration) between alpha 1 and alpha 3 suggests an interconversion of alpha 1 and alpha 3 subpopulations, possibly by cholesteryl ester transfer protein. Pre-beta subpopulations showed an inverse trend with HDL-C, while the pre-alpha subpopulation behaved similarly to the alpha-migrating subpopulation. Colocalization of apoA-I and apoA-II particles in the different HDL subpopulations demonstrated that alpha 1, pre-beta 1, and pre-beta 2 subpopulations are apoA-I-only particles rather than apoA-I:A-II particles.

Role of free apolipoprotein A-I in cholesterol efflux. Formation of pre-alpha-migrating high-density lipoprotein particles

This article characterizes products formed by the interaction of purified apolipoprotein (apo) A-I and human fibroblasts. Fibroblasts were incubated with different concentrations of purified apoA-I (1 to 30 micrograms/mL) in tissue culture medium for different periods of time (0 to 24 hours). The medium was then characterized by one- (agarose) and two-dimensional (agarose: polyacrylamide nondenaturing gradient gel) electrophoresis. At any given concentration of apoA-I, the rate of cellular cholesterol efflux appeared linear over 24 hours. Incubating purified apoA-I with fibroblasts for 4 hours, we detected five pre-alpha lipoproteins with particle sizes between 114 and 684 kDa. Formation of pre-alpha lipoproteins was concentration-dependent. At low concentrations (below 5 micrograms/mL apoA-I), all purified apoA-I (with pre-beta mobility) was converted to pre-alpha lipoproteins. At higher concentrations (greater than 5 micrograms/mL apoA-I), more apoA-I remained with pre-beta mobility. The pre-alpha lipoproteins were characterized by colocalization of apoA-I particles with 14C-cholesterol and 32P-phospholipids. Results showed that the pre-alpha particle of lowest molecular weight contained phospholipid and apoA-I but no cholesterol. The remaining pre-alpha particles contained all three substances. When pre-alpha particles were subjected to ultracentrifugation, all particles floated at d < 1.21 g/mL with some of the smallest phospholipid apoA-I only particles being present in the d > 1.21 g/mL fraction. Based on these results, we postulated that in the first stages of reverse cholesterol transport, pre-alpha lipoproteins are formed by the interaction of lipid free apoA-I and peripheral cells.

Early genes induced in hepatic stellate cells during wound healing

Activation of mesenchymal cells is a central event in the wound healing response of most tissues. In liver, the mesenchymal element responsible for organ fibrosis is the hepatic stellate cell (HSC) (formerly known as lipocyte or Ito cell). The phenotypic cascade of stellate cell activation in liver fibrosis has been well documented and involves both marked morphologic changes and upregulation of several functional components including extracellular matrix, cytokine receptors, contractile filaments and metalloproteinases. However, the genetic regulation of stellate cell activation is poorly understood. In an attempt to clone genes that are involved in the regulation of HSC activation we have combined cDNA library amplification by PCR with subtraction hybridization/differential screening, and have successfully identified genes induced in vivo during early stellate cell activation in a rat model of liver fibrosis. The subtracted cDNA library comprised less than 100 unique sequences. Of these, 13 clones with sizes ranging from 322 to 745 were sequenced and characterized. Gene induction in HSCs was monitored by RNAse protection assay during early liver injury induced by the hepatotoxin CCl4. The sequenced cDNAs corresponding to the known genes included type II transforming growth factor beta receptor, glutathione peroxidase I, transferrin and several clones encoding cellular retrotransposons, whose expression was not previously identified in non-parenchymal liver cells. In addition, one partial cDNA predicted a zinc-finger motif, suggesting a possible role of a novel transcriptional regulator. Our approach represents a valuable strategy for clarifying in vivo regulatory mechanisms of mesenchymal cell activation in wound healing.

The enhancement of wound healing with human skin allograft

Although clean incisional wounds can be closed easily, contaminated wounds, wounds with tissue loss that cannot be closed primarily, and chronic wounds are generally not closed and suffer the effects of being open. It follows that wound healing would be enhanced if these wounds could be closed. This article describes how skin allograft biologic dressings are used to close such wounds temporarily to bestow the benefits of wound closure. It also describes the benefits of human skin allografts and the history and basic science related to their use. Reference is made to newer wound covers that have the potential to provide similar benefits to open wounds.

Brachial neuritis presenting as anterior interosseous nerve compression--implications for diagnosis and treatment: a case report

Brachial plexus neuropathy may present as an isolated peripheral nerve lesion, suggesting local compression, when in fact the pathophysiology is a diffuse proximal inflammation. The type of management depends on an accurate diagnosis of the diffuse lesion with electromyography. A descriptive case of isolated anterior interosseus nerve palsy is presented and the literature is reviewed. Analysis of the reported cases reveals that anterior interosseus nerve palsies resulting from different etiologies are included in the same series and that treatment recommendations are highly specialty-oriented. Cases of brachial plexus neuritis-induced anterior interosseus nerve palsy should be managed conservatively, while surgical decompression may be performed for specific instances of direct trauma.

Mother-infant interactions in two strains of rats: implications for dissociating mechanism and function of a maternal pattern

Mother-infant interaction was observed in Long-Evans and Fischer 344 rats after fostering within or across strains. Interactions immediately following introduction of foster pups to the cage as well as undisturbed interactions with resident litters were examined. Some differences were related to alien status, some to strain of pups, and others to strain of dams. Greater responsiveness to pups of the maternal strain was exhibited in retrieval and body licking. Long-Evans pups received more crouching from dams of both strains 3-12 days postpartum, perhaps because they are significantly larger. Regardless of pup strain, Long-Evans dams engaged in more maternal licking than did F344 dams, and this was more likely directed to the anogenital region. Dams of both strains were more likely to lick male than female pups, regardless of pup strain. The strain difference in maternal licking is consistent with adult strain differences in water and salt appetite and may contribute developmentally to the superior copulatory performance of Long-Evans males.

Endocrine abnormalities in ovulatory women with polycystic ovaries on ultrasound

Polycystic-appearing ovaries (PAO) on ultrasound have been described in a variety of endocrinopathies and also occur in ovulatory women. By some investigators this is merely referred to as 'PCO' (polycystic ovaries). Although there is controversy in this regard, we do not consider women with PAO/PCO who have no known endocrine disturbance to have polycystic ovary syndrome (PCOS) and therefore prefer not to use the term 'PCO' which is often equated with PCOS. We studied 15 ovulatory women with normal-appearing (NAO) ovaries on ultrasound and 15 matched ovulatory women with PAO/PCO. Compared to ovulatory women, 25 other women were studied who were considered to have PCOS. Of these, 15 were overweight and 10 were of normal weight. All the PCOS women had serum concentrations of luteinizing hormone (LH), testosterone, unbound testosterone, androstenedione and dihydroepiandrosterone sulphate (DHEAS) which were significantly higher (P < 0.01) than values in the normal women, regardless of ovarian morphology. These values were similar in the two groups of ovulatory women with NAO and PAO/PCO. Fasting insulin was elevated in women with PCOS with increased body weight (P < 0.01) and was higher than in ovulatory women with NAO and PAO/PCO and than in women of normal weight with PCOS. Serum insulin-like growth factor (IGF)-I and binding protein (BP)-3 were similar in all groups but serum IGFBP-1 was significantly (P < 0.01) lower in those women with PCOS with increased body weight, compared to all other groups. Compared to values in ovulatory women with NAO, serum IGFBP-1 was also significantly (P < 0.05) lower in women with PAO/PCO and those women with PCOS of normal weight. These lower values were similar in women with PAO/PCO and in normal weight women with PCOS. On an individual basis, an elevation of at least one serum androgen value was found in 33% of women with PAO/PCO. These data confirm that increased body weight accentuates the metabolic alterations in PCOS, but suggest that subtle endocrine disturbances, similar to those that are found in PCOS, may be uncovered in up to a third of ovulatory women with PAO/PCO. It appears that a disturbance of the IGF/IGFBP-1 axis is common and apparently closely associated with alterations in ovarian morphology.

Delayed birth registration (DBR) in Sao Paulo State: an attempt at correcting underregistration

"The aim of this paper is to analyze the pattern of delayed birth registration [in Brazil] and to establish a relationship with the total and registered births in order to estimate a mathematical function that quantifies birth underregistration."

Proton equilibria in the minor groove of DNA

Poisson-Boltzmann calculations by Pack and co-workers suggest the presence of regions of increased hydrogen ion density in the grooves of DNA. As an experimental test of this prediction, we have attached proton-sensitive probes, with variable linker lengths, to random-sequence DNA at G sites in the minor groove. The amino groups of beta-alanine, gamma-aminobutyric acid (GABA), and epsilon-aminocaproic acid have been coupled at pH 5, via a formaldehyde link, to the exocyclic amino group of guanine, utilizing a reaction that has been extensively investigated by Hanlon and co-workers. The resulting adducts at pH 5 retained duplex B form but exhibited typical circular dichroism (CD) changes previously shown to be correlated with the presence of a net positive charge in the minor groove. Increases in the solvent pH reversed the CD spectral changes in a manner suggesting deprotonation of the carboxylic acid group of the adduct. These data were used to calculate an apparent pK(a) for the COOH. The pK(a) was increased by 2.4 units for beta-alanine, by 1.7 units for GABA, and by 1.5 units for epsilon-amino caproic acid, relative to their values in the free amino acid. This agrees well with Poisson-Boltzmann calculations and the energy minimization of the structures of the adducts that place the carboxyl groups in acidic domains whose hydrogen ion density is approximately 2 orders of magnitude greater than that of bulk solvent.

Helicobacter pylori induces gene expression in human gastric cells identified by mRNA differential display

Changes in gene expression patterns in gastric cells infected with Helicobacter pylori were characterized by means of mRNA differential display. Total RNA preparations were extracted from the H. pylori infected gastric cells and paired non-infected cells, and were probed with candidate clones identified after screening up to 6,000 mRNA species. Among them, four clones, 04G-1, 04G-2, 01G-1, and Cppa-2 show significant expression in the infected cells by Northern blot analysis, and they are 199 bp, 196 bp, 228 bp, and 276 bp in length, respectively. Database search revealed that nucleotide sequences of these clones share very low identity with any known sequence. These results indicate that H. pylori can significantly affect gene expression in gastric cells. Furthermore mRNA differential display can be used in pathogenesis studies to identify new genes in gastric cells in response to insults such as H. pylori.