Perceived barriers and benefits to cervical cancer screening in Latin America

BACKGROUND

This article describes the results of studies on the barriers and benefits of cervical cancer screening from the perspective of women, men, and health providers in five Latin American countries and compares them to other findings from the literature.

METHODS

Five separate qualitative studies (focus groups and interviews) were conducted among low-income women in Venezuela, Ecuador, Mexico, El Salvador, and Peru regarding barriers and benefits of cervical cancer screening. Views from health providers and men were also included.

RESULTS

The main barriers identified by all participants are accessibility and availability of quality services, facilities that lack comfort and privacy, costs, and courtesy of providers, which interact with poor service delivery. Barriers that pertain to women's beliefs are anxiety borne by women awaiting test results, associated with negligence and fear of cancer (although not to a particular cancer or a particular procedure). Benefits of screening are peace of mind and being in control of their health, which then enable other life activities to continue unhindered.

CONCLUSIONS

Except for the accessibility and availability of quality services, these results are consistent with findings from other studies in developed and developing countries. Barriers could be lifted if health service delivery was enhanced, for instance, through quality improvement techniques that are available at low cost. Women's anxiety over test results still needs to be further assessed to devise risk communication strategies that take into account broader cultural frameworks. It is to be noted that such strategies should permeate the way health services are provided for cervical cancer prevention regardless of the specific test used. Vulnerability perceived by low-income women with respect to their capacity to cope with diseases and trust the health services and how this affects their perceptions of risk and their behaviors have not been studied as yet.

Confirmation of cervical neoplasia using a hand-held, lighted magnification device

OBJECTIVES

The objective of this study was to estimate the sensitivity and specificity of visual inspection with acetic acid and magnification (VIAM) using the AviScope device to confirm high-grade cervical intraepithelial neoplasia or carcinoma.

METHODS

VIAM was performed on 142 women aged 18-50 years referred to three colposcopy clinics because of abnormal cervical cytology. Each woman then had a colposcopic examination with cervical biopsy when indicated.

RESULTS

The AviScope device identified 24 of the 40 women who had CIN 2, 3, or carcinoma, yielding a sensitivity of 60.0% (95% CI 43.4, 74.7). The AviScope correctly identified 60 of 87 women negative for dysplasia or cancer, yielding a specificity of 69.0% (95% CI 58.0, 78.2) compared with colposcopy and cervical histology.

CONCLUSION

VIAM using the AviScope device was moderately sensitive and specific for the confirmation of high-grade cervical lesions in women referred with abnormal cervical cytology.

Lives renewed: the emergence of a breast cancer survivor movement in Ukraine

Breast cancer is the leading cause of cancer deaths among women in Ukraine. In addition to the physical toll that breast cancer takes, the psychological and emotional needs of women diagnosed with the disease are great but rarely addressed. Since 1997, with initial technical assistance from the Program for Appropriate Technology in Health (PATH), a nascent breast cancer survivor movement has emerged in Ukraine, which aims to challenge societal stigmatization of the disease. As of mid-2001, survivor groups have been formed in 15 cities, representing 12 of the country's 25 provinces, and groups in eight cities have begun implementing Peer Support Volunteer programmes through which survivors provide information and emotional support to newly diagnosed women in hospital. Survivors also are playing an important role in raising public awareness about the disease through public events, outreach activities and the media. The groups have also forged alliances with key medical professionals specialising in cancer care, both to educate them about the potential role that survivors' groups can play in assisting patients, as well as to enlist their active support for these efforts. Solidifying the groups' organisational structures and strengthening their management and fundraising skills have been vital to success.

Typhoid fever: pathogenesis and disease

Typhoid fever is an infectious disease of global distribution. Although there is a wealth of data on Salmonella typhimurium infection in the mouse and the interaction of this serovar with human cell lines in vitro, there is a relatively small amount of data on S. typhi and the pathogenesis of typhoid fever. In this review we focus on three areas: adherence to and invasion of gut epithelial cells, dissemination to systemic sites, and survival and replication within host cells. In addition, we attempt to put current salmonella research into the context of typhoid fever.

Unnatural ligands for engineered proteins: new tools for chemical genetics

Small molecules that modulate the activity of biological signaling molecules can be powerful probes of signal transduction pathways. Highly specific molecules with high affinity are difficult to identify because of the conserved nature of many protein active sites. A newly developed approach to discovery of such small molecules that relies on protein engineering and chemical synthesis has yielded powerful tools for the study of a wide variety of proteins involved in signal transduction (G-proteins, protein kinases, 7-transmembrane receptors, nuclear hormone receptors, and others). Such chemical genetic tools combine the advantages of traditional genetics and the unparalleled temporal control over protein function afforded by small molecule inhibitors/activators that act at diffusion controlled rates with targets.

Characterization of a Bacillus thuringiensis delta-endotoxin which is toxic to insects in three orders

We report here the first Bacillus thuringiensis (Bt) toxin which is toxic to insects from three insect orders (Diptera, Coleoptera, and Lepidoptera). An oligonucleotide probe based on the delta-endotoxin N-terminal sequence was used to detect the gene. A 23-kb BamHI fragment containing the intact gene was identified and cloned from Bt strain YBT-226 plasmid DNA into the vector pBluescript II. Through a series of DNA manipulations the size of this fragment was reduced and the gene sequenced. The deduced amino acid sequence gave a predicted molecular mass of 137 kDa and was identical to a cry1Ba protein from Bt subsp. thuringiensis HD-2, which is now designated as Cry1Ba1 under a new classification scheme. This protein also showed 81.6% similarity with the Cry1B protein (Cry1Bb1) from Bt strain EG 5847. When the YBT-226 cry1Ba1 gene was expressed in an acrystalliferous Bt subsp. israelensis strain it produced irregular bipyramidal crystals during sporulation, which reacted specifically with anti-Cry1Ba antiserum. Bioassays using these crystals after purification resulted in significant mortality at low to moderate concentrations to larvae of the house fly (Musca domestica, Diptera), cottonwood leaf beetle (Chrysomela scripta, Coleoptera), and tobacco hornworm (Manduca sexta, Lepidoptera). This broad-spectrum toxicity was not dependent on presolubilization. In assays with insect cell lines not derived from midgut cells, the soluble toxin killed CH1t (Manduca sexta cells) but was inactive against CF1 (Choristoneura fumiferana cells), Aa(s) (Aedes aegypti), and C2 (Culex quinquefasciatus) mosquito cells.

Structural basis for selective inhibition of Src family kinases by PP1

BACKGROUND

Small-molecule inhibitors that can target individual kinases are powerful tools for use in signal transduction research. It is difficult to find such compounds because of the enormous number of protein kinases and the highly conserved nature of their catalytic domains. Recently, a novel, potent, Src family selective tyrosine kinase inhibitor was reported (PP1). Here, we study the structural basis for this inhibitor's specificity for Src family kinases.

RESULTS

A single residue corresponding to Ile338 (v-Src numbering; Thr338 in c-Src) in Src family tyrosine kinases largely controls PP1's ability to inhibit protein kinases. Mutation of Ile338 to a larger residue such as methionine or phenylalanine in v-Src makes this inhibitor less potent. Conversely, mutation of Ile338 to alanine or glycine increases PP1's potency. PP1 can inhibit Ser/Thr kinases if the residue corresponding to Ile338 in v-Src is mutated to glycine. We have accurately predicted several non-Src family kinases that are moderately (IC(50) approximately 1 microM) inhibited by PP1, including c-Abl and the MAP kinase p38.

CONCLUSIONS

Our mutagenesis studies of the ATP-binding site in both tyrosine kinases and Ser/Thr kinases explain why PP1 is a specific inhibitor of Src family tyrosine kinases. Determination of the structural basis of inhibitor specificity will aid in the design of more potent and more selective protein kinase inhibitors. The ability to desensitize a particular kinase to PP1 inhibition of residue 338 or conversely to sensitize a kinase to PP1 inhibition by mutation should provide a useful basis for chemical genetic studies of kinase signal transduction.

Protection against aspirin-induced human gastric mucosal injury by bosentan, a new endothelin-1 receptor antagonist

BACKGROUND

Gastric ulceration induced by aspirin and by non-steroidal anti-inflammatory drugs (NSAIDs) is a major clinical problem. The mechanism of injury is unclear. There is evidence that NSAID-induced injury may cause endothelin activation. Endothelin-induced vasoconstriction has been shown to be capable of causing gastric ulceration.

AIM

To investigate whether acute gastroduodenal injury induced in humans by aspirin can be prevented by the endothelin-1 antagonist, bosentan.

METHODS

Eighteen healthy volunteers each received 5 x 900 mg aspirin every 12 h on three separate occasions (with either placebo, bosentan 700 mg or misoprostol 400 mg). Treatment order was randomized by Latin square design. Subjects were endoscoped and erosions counted before and 90 min after the first and last dose of aspirin. Plasma concentrations of bosentan were measured up to 5 h post-dose.

RESULTS

There was a significant reduction in the mean number of erosions in the aspirin plus bosentan and aspirin plus misoprostol groups after the first dose of aspirin, compared with controls (aspirin plus placebo) (P<0.05). This was not sustained after the fifth dose of aspirin in the aspirin plus placebo and aspirin plus bosentan groups, but was still present in the aspirin plus misoprostol group. The mean plasma concentration of bosentan measured 3.5 h post-dose fell from 4510 (95% CI: 2791-6230) ng/mL after the 1st dose to 2508 (95% CI: 1733-3283) ng/mL after the 5th dose (P = 0.02).

CONCLUSION

Endothelin receptor antagonism by bosentan can protect the gastric mucosa against aspirin damage. After five doses, bosentan levels fell, possibly because of enzyme induction, and protection was no longer evident. Further investigation is needed to assess whether higher doses would be effective.

Adaptive resistance to nitric oxide in motor neurons

Nitric oxide (NO) is a free radical produced actively by mammalian cells, including neurons. Low levels of NO can function in intercellular signaling, but high levels are cytotoxic. This cytotoxic potential suggests that cells at risk for NO damage, such as neurons, might have NO resistance mechanisms to prevent cell death, and adaptive resistance to NO-releasing compounds has been reported for some non-neuronal cell types. Here we show that immortalized mouse motor neurons (NSC34 cells) respond to sub-lethal fluxes of pure NO by activating adaptive resistance mechanisms that counteract cytotoxic NO exposure. This adaptive NO resistance is reversible and is paralleled by the induction of the oxidative stress enzyme heme oxygenase 1 (HO-1). An inhibitor of both HO-1 and heme-dependent guanylate cyclase (tin-protoporphyrin IX) greatly sensitized NO-pretreated NSC34 cells to the NO challenge. However, readdition of cyclic GMP (in the form of the 8-bromo derivative) restored rather little resistance, and a more selective guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxaline-1-one (at 10 microM), did not have the sensitizing effect. Therefore, the inducible HO-1 pathway contributes substantially to adaptive NO resistance, while cyclic GMP seems to play at most a small role. A similar adaptive resistance to NO was observed in primary rat spinal chord motor neurons. The activation of NO resistance in motor neurons may counteract age- or disease-related neurodegeneration.

Erosive oesophagitis: outcome of repeated long term maintenance treatment with low dose omeprazole 10 mg or placebo

AIMS

To investigate the efficacy of daily maintenance treatment with omeprazole 10 mg in reducing the relapse rate of healed erosive oesophagitis.

METHODS

Three hundred patients with erosive oesophagitis (grade 2 or greater) received omeprazole 20 mg daily for 12 weeks, followed by 40 mg daily for a further 12 weeks if required. After healing, patients were randomised to double blind treatment with omeprazole 10 mg daily or placebo for up to 18 months. On relapse the treatment cycle was repeated.

RESULTS

The cumulative healing rate at 12 weeks in the initial healing period was 95%, and 96% and 98% on rehealing courses after relapse in the first and second maintenance periods respectively. After 12 weeks of treatment, 98% of patients were free from heartburn and 97% were free of all reflux related symptoms. Relapse in the subgroup of patients who relapsed in both maintenance periods was infrequent on omeprazole 20 mg daily: only 9% at two years. Gastrin concentrations rose above normal in one third of patients. One patient had linear hyperplasia of endocrine cells and another had micronodular hyperplasia. There were no side effects definitely attributable to omeprazole.

CONCLUSION

Maintenance treatment with omeprazole 10 mg daily keeps about 60% of patients with erosive oesophagitis in prolonged remission. Patients relapsing once are likely to do so again; they can subsequently be treated effectively with omeprazole 20 mg daily.

Pyrroloquinoline quinone: a novel vitamin?

Pyrroloquinoline quinone (PQQ), otherwise known as methoxatin, is a water-soluble, redox-cycling orthoquinone that was initially isolated from cultures of methylotropic bacteria. It has been found to be a cofactor of some bacterial alcohol dehydrogenases, and is present in many animal tissues. It may be a novel vitamin because it has been shown to be essential for normal growth and development. The redox-cycling ability of PQQ enables it to scavenge or generate superoxide. When fed to animals as a supplement, PQQ prevents oxidative changes that would ordinarily occur. It has been reported to inhibit glutamate decarboxylase activity and protect against N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity in the brain. It appears that in the whole animal, however, PQQ does not cross the blood-brain barrier. Furthermore, it increases nerve growth factor (NGF) synthesis in mouse astroglial cells, but has to be bound to glycine to penetrate and exert this effect in whole brain. It may therefore be regarded as a "Janus faced" molecule, with its potential for a therapeutic role in the brain still in question.

Alterations in heart failure of cyclic AMP-dependent inotropic and lusitropic properties of cardiac and skeletal muscle

A central working hypothesis in our laboratory is that deficient cellular cyclic AMP concentrations may be responsible, at least in part, for striated muscle dysfunction, both cardiac and skeletal, in heart failure. These results suggest that therapy aimed at restoring cyclic AMP to normal levels may be effective with regard to improving systolic and diastolic function in the heart and may decrease the development of fatigue in skeletal muscle of patients with failure. The use of cyclic AMP-dependent drugs in clinical practice has been limited by side effects associated with raising total cellular content of this cyclic nucleotide. However, evidence suggesting that separate pools of cyclic AMP may exist within the cell raises the possibility that those pools associated with excitation/contraction coupling could serve as more specific therapeutic targets.

Hydrophobic forces dominate the thermodynamic characteristics of UvrA-DNA damage interactions

The Escherichia coli DNA repair proteins UvrA, UvrB and UvrC work together to recognize and incise DNA damage during the process of nucleotide excision repair (NER). To gain an understanding of the damage recognition properties of UvrA, we have used fluorescence spectroscopy to study the thermodynamics of its interaction with a defined DNA substrate containing a benzo[a]pyrene diol epoxide (BPDE) adduct. Oligonucleotides containing a single site-specifically modified N2-guanine (+)-trans-, (-)-trans-, (+)-cis-, or (-)-cis-BPDE adducts were ligated into 50-base-pair DNA fragments. All four stereoisomers of DNA-BPDE adducts show an excitation maximum at 350 nm and an emission maximum around 380 to 385 nm. Binding of UvrA to the BPDE-DNA adducts results in a five to sevenfold fluorescence enhancement. Titration of the BPDE-adducted DNA with UvrA was used to generate binding isotherms. The equilibrium dissociation constants for UvrA binding to (+)-trans-, (-)-trans-, (+)-cis-, and (-)-cis- BPDE adduct were: 7.4+/-1.9, 15. 8+/-5.4, 11.3+/-2.7 and 22.4+/-2.0 nM, respectively. There was a large negative change in heat capacity DeltaCpo,obs, (-3.3 kcal mol-1 K-1) accompanied by a relatively unchanged DeltaGoobs with temperature. Furthermore, varying the concentration of KCl showed that the number of ions released upon formation of UvrA-DNA complex is about 3.4, a relatively small value compared to the contact size of UvrA with the substrate. These data suggest that hydrophobic interactions are an important driving force for UvrA binding to BPDE-damaged DNA.

Histamine H2 receptor antagonist-refractory oesophagitis: the efficacy of long-term omeprazole maintenance treatment

BACKGROUND

Erosive oesophagitis refractory to high dose histamine H2 receptor antagonists (definition: failure to heal fully after > or = 3 months' treatment with cimetidine 3.2 g or ranitidine 0.9 g) responds well to omeprazole 40 mg daily but frequently relapses when the patients are put back on maintenance H2 receptor antagonists at medium or even high dose (e.g. cimetidine 1.6 g and 3.2 g, respectively).

AIM

To investigate the efficacy of maintenance omeprazole 20 mg daily in refractory erosive oesophagitis.

PATIENTS & METHODS

In this open, sequential study, patients with H2 receptor antagonist-refractory oesophagitis were healed on omeprazole 40 mg daily and then put on maintenance H2 receptor antagonists (cimetidine 1.6 g or 3.2 g). Relapses were re-treated with omeprazole 40 mg; upon rehealing, patients were put on maintenance omeprazole 20 mg daily for up to 4.5 years.

RESULTS

Healing on omeprazole occurred in 38 out of 39 patients (97%) at 12 weeks. Only six of the 38 patients (16%) relapsed (asymptomatic in half) during subsequent maintenance treatment, whereas all had relapsed earlier on high dose H2 receptor antagonists.

CONCLUSION

Within the limits of interpretation of an open study, omeprazole 20 mg daily seems effective in maintaining prolonged remission in this group of patients with H2 receptor antagonist-refractory oesophagitis.

Right ventricular dysfunction during coronary artery occlusion: pressure-volume analysis using conductance catheters during coronary angioplasty

OBJECTIVE

To study the effects of coronary artery occlusion on the pressure-volume relations of the right ventricle.

DESIGN

Right ventricular pressure-volume cycles were studied using conductance catheters and micromanometers in 19 subjects undergoing coronary angioplasty in a tertiary referral cardiac centre.

RESULTS

Catheter occlusions of either the left anterior descending coronary artery or the right coronary artery were associated with a decline in stroke work (mean change (SD): left-13.3 (15.8)%, p = 0.008; right -13.5(16.5)%, p = 0.04). Two patterns of change were evident: an upward shift usually associated with occlusion in the left coronary artery, and a rightward shift in the right coronary artery. In the former there was an increase in maximum ventricular volume (mean change: 3.0(2.7)%, p = 0.004) and in minimum ventricular volume (mean change: 2.3(2.7)%, p = 0.01) and a fall in peak pressure (mean change: -4.8 (5.1)%, p = 0.04). In the latter there was an increase in peak pressure (mean change 9.9(16.3)%, p = 0.04) and an increase in minimum ventricular volume (mean change 3.7(5.0)%, p = 0.02) leading to a fall in stroke volume (mean change -13.3(15.8)%, p = 0.008).

CONCLUSIONS

Occlusion of the left anterior descending coronary artery or the right coronary artery is associated with a decline in right ventricular work. However, different patterns of change in indices of preload and afterload lead to different effects on overall right ventricular pump function.

Increased airway pressure and simulated branch pulmonary artery stenosis increase pulmonary regurgitation after repair of tetralogy of Fallot. Real-time analysis with a conductance catheter technique

BACKGROUND

Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right ventricular pressure-volume loops with a conductance catheter. Subsequently, the impact of two loading maneuvers (increased airway pressure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method.

METHODS AND RESULTS

Thirteen patients, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvotomy, had PR measured by MR phase velocity mapping while breathing spontaneously. During catheterization under general anesthesia. PR was estimated from right ventricular pressure-volume loops generated by conductance and microtip pressure catheters. The effect of increased airway pressure (continuous positive airway pressure, 20 cm H2O; n = 12) and simulated branch pulmonary artery stenosis (transient balloon occlusion of a branch pulmonary artery, n = 7) was measured. Basal PR fraction derived by MR and from right ventricular pressure-volume loops had a correlation coefficient of .76 and mean of differences of 2.0 +/- 18.2% (95% limits of agreement). Increased airway pressure increased PR (16.3 +/- 11.4% to 25.7 +/- 17.3%, P < .01). Simulated branch pulmonary artery stenosis increased right ventricular end-systolic pressure (69.1 +/- 21.4 to 78.7 +/- 23.1 mm Hg, P < .05) and PR (27.5 +/- 11.3% to 36.9 +/- 12.8%, P < .05).

CONCLUSIONS

There was reasonable agreement between MR phase velocity-derived PR fraction and that obtained from right ventricular pressure-volume loops generated by use of conductance and pressure-microtip catheters. Exacerbation of PR by increased airway pressure and branch pulmonary stenosis may be relevant to the acute postoperative and long-term management, respectively, of patients after repair of tetralogy of Fallot.

Clinical application of the conductance catheter technique in the adult human right ventricle

This study examines the use of conductance catheters to assess human right ventricular volume. Ten patients undergoing diagnostic cardiac catheterisation underwent right heart catheterisation with a conductance catheter and micromanometer, and a thermodilution catheter before and after fluid loading. Parallel wall conductance (Vc), and the multiplication factor relating conductance and thermodilution derived stroke volumes (å) were derived at each steady state. Pressure-volume cycles were analyzed at steady state and during fluid loading. Fluid loading resulted in a significant increase in cardiac output, and change in maximum and minimum cycle volume. There was no significant change in å (mean 0.40 S.D. 0.20) or Vc (mean 126.4 S.D. 59.6 ml) at higher cardiac outputs or ventricular volumes. Right ventricular pressure-volume cycles were formed demonstrating characteristic lack of clear isovolumic contraction and relaxation phases, and low cycle efficiencies (mean 0.62 S.D. 0.16). Serial cycles recorded during volume loading defined an end systolic pressure-volume relation more reliably than a stroke work end diastolic volume relation. Thus, a conductance derived volume signal can be obtained in the human right ventricle which can be interpreted as a continuous and instantaneous index of right ventricular volume, allowing the construction of real time pressure-volume cycles.

Resting right ventricular function in patients with coronary artery disease: pressure volume analysis using conductance catheters

Right ventricular pressure volume cycles from patients with coronary artery disease were created in order to assess their characteristics and the effects of peak ventricular pressure and right and left artery coronary disease. Thirty-three patients undergoing diagnostic catheterisation for ischaemic heart disease underwent right ventricular catheterisation with a micromanometer and a conductance catheter. Simultaneous pressure and volume signals were recorded and analysed as functions of time, and of each other, forming pressure volume cycles. A total of 19/33 (58%) patients had an abnormal pressure volume loop with a clear end systolic shoulder, and an isovolumic relaxation phase. The mean peak ventricular pressure for all patients was raised (35.2 S.D. 11.8 mmHg), but there was no correlation between indices of shape and peak systolic pressure. Values of dP/dtmax were also raised, but there was no significant difference in this or any other index between patients with left or right coronary artery disease. Thus, in patients with coronary artery disease, the right ventricular pressure volume loop is frequently abnormal in a pattern that is recognised as a feature of an increased ventricular afterload.