Dengue determinants: Necessities and challenges for universal dengue vaccine development

Dengue illness can range from mild illness to life-threatening haemorrhage. It is an Aedes-borne infectious disease caused by the dengue virus, which has four serotypes. Each serotype acts as an independent infectious agent. The antibodies against one serotype confer homotypic immunity but temporary protection against heterotypic infection. Dengue has become a growing health concern for up to one third of the world's population. Currently, there is no potent anti-dengue medicine, and treatment for severe dengue relies on intravenous fluid management and pain medications. The burden of dengue dramatically increases despite advances in vector control measures. These factors underscore the need for a vaccine. Various dengue vaccine strategies have been demonstrated, that is, live attenuated vaccine, inactivated vaccine, DNA vaccine, subunit vaccine, and viral-vector vaccines, some of which are at the stage of clinical testing. Unfortunately, the forefront candidate vaccine is less than satisfactory, and its performance depends on serostatus and age factors. The lessons from clinical studies depicted ambiguity concerning the efficacy of dengue vaccine. Our study highlighted that viral structural heterogeneity, epitope accessibility, autoimmune complications, genetic variants, genetic diversities, antigen competition, virulence variation, host-pathogen specific interaction, antibody-dependent enhancement, cross-reactive immunity among Flaviviruses, and host-susceptibility determinants not only influence infection outcomes but also hampered successful vaccine development. This review integrates dengue determinants allocated necessities and challenges, which would provide insight for universal dengue vaccine development.     

Characterization of α1-adrenoceptor subtypes mediating contractions to phenylephrine in rat thoracic aorta,mesenteric artery and pulmonary artery

1. The subtype of α₁-adrenoceptor mediating contractions to phenylephrine of the rat thoracic aorta, mesenteric artery and pulmonary artery were investigated by use of antagonists which show selectivity between the cloned α₁-adrenoceptor subtypes in binding studies.
2. Cumulative concentration-contraction curves for phenylephrine were competitively antagonized in the rat thoracic aorta by prazosin (pA₂ 9.9), WB4101 (pA₂ 9.6), 5-methylurapidil (pA₂ 8.1), benoxathian (pA₂ 9.2) and indoramin (pA₂ 7.4). These compounds were also competitive antagonists in the mesenteric and pulmonary arteries (except for 5-methylurapidil in the pulmonary artery), (prazosin pA₂ 9.9 and 9.7; WB4101 pA₂ 9.8 and 9.6; 5-methylurapidil pA₂ 7.9 and pK_B estimate 8.0; benoxathian pA₂ 8.8 and 9.3; indoramin pA₂ 7.2 and 7.5, respectively).
3. RS 17053 was not a competitive antagonist in any blood vessel as Schild plot slopes were greater than unity. The pK_B estimates for RS 17053 were 7.1 in aorta, 7.0 in the mesenteric artery and 7.7 in the pulmonary artery.
4. The α_1D-subtype selective antagonist BMY 7378 appeared to be non-competitive with shallow Schild plot slopes. The data were better fitted with two lines in all tissues, with Schild plot slopes that were no longer different from unity, except in the pulmonary artery. The higher affinity site for BMY 7378 in the aorta had a pA₂ of 9.0, while it was 8.8 and 8.9 in the mesenteric and pulmonary arteries, respectively.
5. MDL73005EF acted in a non-competitive manner in all three blood vessels, with shallow Schild plot slopes. The pK_B estimates for MDL73005EF were 8.4 in aorta, 7.5 in the mesenteric artery and 8.0 in the pulmonary artery.
6. In all three blood vessels the functionally determined antagonist affinity estimates correlated best with published pK_i values for their displacement of [³H]-prazosin binding on membranes expressing cloned α_1d-adrenoceptors compared with α_1a- or α_1b-adrenoceptors. The antagonist affinity estimates in the aorta, mesenteric and pulmonary arteries correlated highly with their previously published pA₂ values in rat aorta (α_1D) and less well with those for α_1A- and α_1B-adrenoceptors mediating contraction of the rat epididymal vas deferens and rat spleen, respectively.
7. The results of this study suggest that the contraction to phenylephrine of the rat thoracic aorta, mesenteric artery and pulmonary artery are mediated in part via the α_1D-subtype of adrenoceptor. The data for both BMY 7378 and MDL73005EF in all three blood vessels are consistent with receptor heterogeneity. However, the identity of the second site is unclear.

     

Autoregulation of nitric oxide-soluble guanylate cyclase-cyclic GMP signalling in mouse thoracic aorta

1. The sensitivity of the soluble guanylate cyclase (sGC)-cyclic guanosine-3',5'-monophosphate (cyclic GMP) system to nitric oxide (NO) was investigated in mouse aorta from wild type (WT) and NO synthase (NOS) knockout (KO) animals. 2. The NO donor, spermine-NONOate (SPER-NO) was more potent in aortas from eNOS KO mice compared to WT (pEC50 7.30+/-0.06 and 6.56+/-0.04, respectively; n=6; P<0.05). In contrast, the non-NO based sGC activator, YC-1 was equipotent in vessels from eNOS WT and KO mice. The sensitivity of aortas from nNOS and iNOS KO animals to SPER-NO was unchanged. Forskolin (an adenylate cyclase activator), was equipotent in vessels from eNOS WT and KO animals. 3. The cyclic GMP analogue, 8-Br-cGMP was equipotent in eNOS WT and KO mice (pEC50 4. 38+/-0.04 and 4.40+/-0.05, respectively; n=5; P>0.05). Zaprinast (10-5 M) a phosphodiesterase type V (PDE V) inhibitor, had no effect on the response to SPER-NO in vessels from eNOS WT or KO mice. 4. The NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 3x10-4 M) increased the potency of SPER-NO in aortas from WT mice (pEC50 6. 64+/-0.02 and 7.37+/-0.02 in the absence and presence of L-NAME, respectively; n=4; P<0.05). 5. In summary, there is increased sensitivity of vessels from eNOS KO animals to NO. Cyclic AMP-mediated dilatation is unchanged, consistent with a specific up-regulation of sGC - cyclic GMP signalling. The functional activity of cyclic GMP-dependent protein kinase (G-kinase) and PDE V was also unchanged, suggesting that sGC is the site of up-regulation. These alterations in the sensitivity of the sGC - cyclic GMP pathway might represent a mechanism for the dynamic regulation of NO bioactivity.     

Degradation Kinetics of BMP 777, an Elastase Inhibitor

Purpose. The objective was to evaluate the degradation profile of the elastase inhibitor DMP 777 and lay the foundation for formulation development. Methods. The pK_a was determined by potentiometric titration in mixed-aqueous solvents. The degradation kinetics were studied as a function of pH, buffer concentration, ionic strength, methanol concentration and temperature using a stability-indicating HPLC assay. The degradation products were identified by LC-MS, NMR, and by comparison with authentic samples. Results. The pK_a for the protonated piperazine nitrogen was estimated to be 7.04. The pH-rate profile is described by specific acid-, water-, and specific base-catalyzed pathways. The pH of maximum stability is in the range of 4 to 4.5 where water is the principal catalyst in the reaction. Buffer catalysis, primary salt effects and medium effects were observed. The proposed mechanism for acid catalyzed degradation is the rarely observed A_AL1 which involves alkyl-nitrogen heterolysis. The driving force for the reaction appears to lie in the stability of the benzylic carbocation. The proposed mechanism for base catalyzed degradation is B_AC2 which involves -lactam ring opening. The -lactam ring of DMP 777, a monolactam, appears to be as reactive as that in benzylpenicillin in the k _OH controlled region where a similar mechanism of hydrolysis should be operative. A contributing factor to this increased reactivity may lie in the reduced basicity of the -lactam nitrogen making it a good leaving group. Conclusions. The degradation profile indicates that development of a solution dosage form of DMP 777 with adequate shelf-life stability at room temperature is feasible.     

Prostate cancer old problems and new approaches

Rates of prostate cancer (PCa) have increased so dramatically over the last decade that the age adjusted incidence rate for PCa is now greater than that any other cancer among men in the United States. This review, published as a three part series, provides a state-of-art assessment of the PCa problem in its divergent aspects.Part 1 covers epidemiology, incidence and progression. Several epidemiological studies have demostrated that first degree male relatives of men with PCa are at increased risk of developing the disease. Familial and genetic factors as well as medical, anthropometric, dietary, hormonal and occupational factors involved in PCa are discussed. Postmortem examination of the prostate in men without evidence of PCa documented a high frequency of adenocarcinoma. Latent disease occurred as early as the second decade of life. Although there is no significant difference in incidence between Caucasian and African-American males, high grade prostatic intraepithelial neoplasia (HGPIN) is higher in the latter group. While dietary fat, androgens and certain environmental factors may be determinants for PCa, the exact mechanism of tumorigenesis is still relatively unknown. The current thinking of the role of genomic instability, chromosomal alterations, tumor suppressor genes and the androgen receptor are explored.     

Attitudes to smoking and smoking habits among hospital staff.

BACKGROUND: Health professionals should take an active role against smoking, so it is relevant to have information on their smoking habits and their attitudes towards smoking, especially with a view to identifying and offering help to those smokers who wish to stop. Staff in Llandough Hospital were surveyed to determine their smoking habits and attitudes, and the findings were compared with those of a similar survey at Llandough in 1987. METHODS: In October 1991 a questionnaire was sent to each member of staff employed half time or more requesting data on age, sex, department, smoking habit, attitudes to smoking in various areas of the hospital, and attitudes to access to smoking rest rooms for patients, staff, and visitors. Smokers were asked whether they would like to join a "quit smoking" group. Non-responders were sent a reminder four weeks later and all replies returned by 31 December 1991 were analysed. RESULTS: The response rate was 82%; of the respondents, 65% were non-smokers, 15% ex-smokers, and 20% current smokers. The prevalence of current smokers was 5% among doctors, 20% among nurses, 18% among administrative and clerical staff, and 40-42% among domestics, catering, and portering staff. Thirty eight per cent of responders wished smoking to be completely forbidden in all areas of the hospital and 90% in certain areas such as wards, offices, cafeteria, and laboratories. Nearly half wanted smoking to be allowed in rest rooms and over 60% wanted a 24 hour facility for smoking for staff, 56% for patients, and 44% for visitors. Only 39% of smokers wished to join a "quit smoking" support group. In comparison with the 1987 survey, the response rate in this study was higher (82% v 70%), the proportion of non-smokers had increased (65% v 59%), and more smokers wanted help (39% v 26%). Fewer wanted 24 hour access to smoking areas for staff and for visitors. CONCLUSION: This hospital should capitalise on these changes of attitude among staff and proceed more rapidly with the implementation of policies to further reduce smoking among staff, visitors, and patients. As a first step a smoking cessation counsellor has been appointed.     

The prevalence, classification and treatment of mental disorders among attenders of native faith healers in rural Pakistan

  Background: Although native faith healers are found in all parts of Pakistan, where they practice in harmony with the cultural value system, their practice is poorly understood. This study investigated the prevalence, classification and treatment of mental disorders among attenders at faith healers. Method: The work of faith healers with 139 attenders was observed and recorded. The mental status of attenders was assessed using a two-stage design: screening using the General Health Questionnaire followed by diagnostic interview using the Psychiatric Assessment Schedule. Results: The classification used by faith healers is based on the mystic cause of disorders: saya (27%), jinn possession (16%) or churail (14%). Sixty-one percent of attenders were given a research diagnosis of mental disorder: major depressive episode (24%), generalized anxiety disorder (15%) or epilepsy (9%). There was little agreement between the faith healers' classification and DSM-IIIR diagnosis. Faith healers use powerful techniques of suggestion and cultural psychotherapeutic procedures. Conclusions: Faith healers are a major source of care for people with mental health problems in Pakistan, particularly for women and those with little education. Further research should assess methods of collaboration that will permit people with mental health problems to access effective and culturally appropriate treatment. Accepted: 9 June 2000