Botulinum neurotoxins and botulism: a novel therapeutic approach

Specific treatment is not available for human botulism. Current remedial mainstay is the passive administration of polyclonal antibody to botulinum neurotoxin (BoNT) derived from heterologous species (immunized animal or mouse hybridoma) together with supportive and symptomatic management. The antibody works extracellularly, probably by blocking the binding of receptor binding (R) domain to the neuronal receptors; thus inhibiting cellular entry of the holo-BoNT. The antibody cannot neutralize the intracellular toxin. Moreover, a conventional antibody with relatively large molecular size (150 kDa) is not accessible to the enzymatic groove and, thus, cannot directly inhibit the BoNT zinc metalloprotease activity. Recently, a 15-20 kDa single domain antibody (V(H)H) that binds specifically to light chain of BoNT serotype A was produced from a humanized-camel VH/V(H)H phage display library. The V(H)H has high sequence homology (>80%) to the human VH and could block the enzymatic activity of the BoNT. Molecular docking revealed not only the interface binding between the V(H)H and the toxin but also an insertion of the V(H)H CDR3 into the toxin enzymatic pocket. It is envisaged that, by molecular linking the V(H)H to a cell penetrating peptide (CPP), the CPP-V(H)H fusion protein would be able to traverse the hydrophobic cell membrane into the cytoplasm and inhibit the intracellular BoNT. This presents a novel and safe immunotherapeutic strategy for botulism by using a cell penetrating, humanized-single domain antibody that inhibits the BoNT by means of a direct blockade of the groove of the menace enzyme.     

Risk of Methylphenidate‐Induced Prehypertension in Normotensive Adult Smokers With Attention Deficit Hyperactivity Disorder

The authors studied predictors of methylphenidate‐induced increases in blood pressure (BP). In this secondary analysis of a randomized, double‐blind, placebo‐controlled smoking cessation trial, nonhypertensive adult smokers with attention deficit hyperactivity disorder randomized to osmotic‐release oral system methylphenidate (OROS‐MPH) (n=115) were matched one‐to‐one on baseline systolic BP (SBP) (±5 mm Hg) with participants randomized to placebo (n=115) and followed for 10 weeks. In adjusted mixed linear models of SBP and diastolic BP (DBP), baseline normal SBP (P<.0001) and DBP (P<.0001) were associated with significant OROS‐MPH–induced increases compared with placebo, whereas significant increases were not observed in participants with baseline prehypertensive SBP (P=.27) and DBP (P=.79). Participants randomized to OROS‐MPH with baseline normal BP had increased odds of developing either systolic (odds ratio [OR], 3.32; 95% confidence interval [CI], 1.41–8.37; P=.006) or diastolic prehypertension (OR, 4.32; 95% CI, 1.56–14.0; P=.004) compared with placebo using simple logistic regression. The authors demonstrated an augmented OROS‐MPH–induced BP elevation and risk of prehypertension in adults with baseline normal BP. Significantly increased BP was not observed in adults with baseline prehypertension. J Clin Hypertens (Greenwich). 2012; 00:00–00. ©2012 Wiley Periodicals, Inc.     

Candida in oral lichen planus patients undergoing topical steroid therapy.

OBJECTIVES: To determine the incidence, intensity, and species of Candida in the oral cavity of oral lichen planus (OLP) patients who were being treated with a topical steroid. STUDY DESIGN: The incidence and intensity of oral Candida carriage were assessed by salivary and imprint cultures. Cytological smears were used to investigate the presence of Candida spores and hyphae in the OLP lesions. Candida species were identified by a chlamydospore formation test and the API 20C system. RESULTS: The salivary cultures were positive in 76.7% of the OLP patients and 43.3% of the controls (P = .008), whereas the imprint cultures were positive in 76.7% of the OLP patients and 40% of the controls (P = .004). A high-level Candida count in saliva was more frequently found in the OLP patients than in the controls (73.9% vs. 38.5%; P = .004). The mean scores of Candida growth from imprint cultures were higher in OLP patients than in the controls (P = .002). The mean scores of Candida growth were also higher in OLP patients who were taking xerogenic or immunosuppressive drugs (P = .038) and in OLP denture wearers (P = .022). Spores and hyphae were detected in 83.3% of the OLP lesions. Candida albicans, the most frequently isolated yeast, was found in 76.7% OLP patients and 40% of the controls. CONCLUSIONS: The results of this study indicate that topical steroids induce Candida growth and the associated risk factors are age, medication use, and the wearing of dentures.     

Blastocystis hominis infection in irritable bowel syndrome patients

Irritable bowel syndrome (IBS) is a functional bowel disorder in which abdominal pain is associated with a defect or a change in bowel habits. Subtle inflammation, especially after infectious enteritis, has been sometimes suspected as one mechanism of pathogenesis. This research was performed (1) to evaluate the prevalence of parasitic infections and (2) the possible association of IBS and parasitic infections. Fifty-nine IBS patients were recruited using symptom-based criteria (Rome Criteria II) with an absence of intestinal parasitic infection by direct smear method. Stool samples of individual patients were examined using 7 methods, ie examination for stool occult blood, simple saline smear method, formalin-ether technique, culture for Blastocystis hominis, modified trichrome stain, modified Ziehl-Neelsen method, and trichrome stain for parasitic and bacterial infections. Of the 59 patients, stool samples of 13 patients (22.1%) were positive for parasites. These were B. hominis (13.6%), Strongyloides stercoralis larvae (1.7%), Giardia lamblia cysts (1.7%), and non-pathogenic protozoa, ie Endolimax nana cysts (5.1%). The prevalence rate of parasitic infections in the control group (20%) was not statistically different from the patients. There was no statistical difference between B. hominis infection in IBS patients and control was found in this study (p = 0.87). In the IBS group, B. hominis infection predominated (13.6%), while other parasitic infections were found in 8.5%. The culture method for B. hominis is more sensitive than the direct (simple) stool smear method, which is the routine diagnostic method in most laboratories. These results were also found in control group.     

Cost‐Effectiveness of Therapeutic Drug Monitoring in Diagnosing Primary Aldosteronism in Patients With Resistant Hypertension

Primary aldosteronism (PA) is present in up to 20% of patients with treatment‐resistant hypertension (TRH). Investigation for PA in patients with TRH is recommended by current guidelines after medication nonadherence is excluded. Studies using therapeutic drug monitoring (TDM) have shown that >50% of patients with TRH are nonadherent to their prescribed antihypertensive medications. However, the relationship between the prevalence of PA and medication adherence as confirmed by TDM has not been previously assessed. A retrospective analysis from a hypertension referral clinic showed that prevalence of PA in adherent patients with TRH by TDM was significantly higher than in nonadherent patients (28% vs 8%, P<.05). Furthermore, cost analysis showed that TDM‐guided PA screening was $590.69 less expensive per patient, with minimal impact on the diagnostic accuracy. These data support a TDM‐guided PA screening approach as a cost‐saving strategy compared with routine PA screening for TRH.     

Childhood TB epidemiology and treatment outcomes in Thailand: a TB active surveillance network, 2004 to 2006

Background

Hepatitis B virus (HBV) infection is a significant public health problem that may lead to chronic liver disease, cirrhosis, and hepatocellular carcinoma (HCC). Approximately 30% of the world's population has been infected with HBV and approximately 350 million (5–6%) are persistent carriers. More than 120 million Chinese are infected with HBV. The role of host genetic factors and their interactions with environmental factors leading to chronic HBV infection and its complications are not well understood. We believe that a better understanding of these factors and interactions will lead to more effective diagnostic and therapeutic options.

Methods/Design

This is a population-based, case-control study protocol to enroll 2200 Han Chinese from medical centers in northern and western China. Adult subjects in the following groups are being enrolled: healthy donors (n = 200), HBV infected persons achieving virus clearance (n = 400), asymptomatic HBV persistent carriers (n = 400), chronic hepatitis B cases (n = 400), decompensated liver cirrhosis with HBV infection cases (n = 400), and hepatocellular carcinoma with HBV infection cases (n = 400). In addition, for haplotype inference and quality control of sample handling and genotyping results, children of 1000 cases will be asked to provide a buccal sample for DNA extraction. With the exception of adult patients presenting with liver cirrhosis or HCC, all other cases and controls will be 40 years or older at enrollment. A questionnaire is being administered to capture dietary and environmental risk factors. Both candidate-gene and genome-wide association approaches will be used to assess the role of single genetic factors and higher order interactions with other genetic or environmental factors in HBV diseases.

Conclusion

This study is designed and powered to detect single gene effects as well as gene-gene and environmental-gene interactions. The identification of allelic polymorphisms in genes involved in the pathway leading to chronic viral infection, liver cirrhosis and, ultimately, hepatocellular carcinoma would provide insights to those factors leading to HBV replication, liver inflammation, fibrosis, and the carcinogenic process. An understanding of the contribution of host genetic factors and their interactions may inform public health policy, improve diagnostics and clinical management, and provide targets for drug development.     

Relationship between sympathetic baroreflex sensitivity and arterial stiffness in elderly men and women

Previous human studies have shown that large-artery stiffness contributes to an age-related decrease in cardiovagal baroreflex sensitivity. Whether this is also true with sympathetic baroreflex sensitivity is unknown. We tested the hypothesis that sympathetic baroreflex sensitivity is associated with the stiffness of baroreceptor segments (the carotid artery and the aorta) in elderly individuals and that sex affects this relationship. Sympathetic baroreflex sensitivity was assessed from the spontaneous changes in beat-by-beat diastolic pressure and corresponding muscle sympathetic nerve activity (microneurography) during supine rest in 30 men (mean±SEM: 69±1 years) and 31 women (68±1 years). Carotid artery stiffness (B-mode ultrasonography) and aortic stiffness (MRI) were also determined. We found that elderly women had lower sympathetic baroreflex sensitivity than elderly men (-2.33±0.25 versus -3.32±0.25 bursts · 100 beats(-1) · mm Hg(-1); P=0.007). β-Stiffness indices of the carotid artery and the aorta were greater in elderly women than in men (6.68±0.48 versus 5.10±0.50 and 4.03±0.47 versus 2.68±0.42; both P<0.050). Sympathetic baroreflex sensitivity was inversely correlated with carotid artery stiffness in both men and women (r=0.49 and 0.50; both P<0.05), whereas this relation was shifted in parallel upward (toward a reduced sensitivity) in women with no changes in the slope (0.26 versus 0.24 arbitrary units). Sympathetic baroreflex sensitivity and aortic stiffness showed similar trends. Thus, barosensory artery stiffness seems to be one independent determinant of sympathetic baroreflex sensitivity in elderly men and women. The lower sympathetic baroreflex sensitivity in elderly women may predispose them to an increased prevalence of hypertension.     

Heterosubtypic immunity to influenza mediated by liposome adjuvanted H5N1 recombinant protein vaccines

A non-egg, non-culture based influenza vaccine that intervenes large influenza outbreaks and protects against heterosubtypic infections is needed. Candidates of such vaccine are likely to be conserved influenza virus proteins or their coding DNA. The vaccine must be conveniently produced at reasonable cost, safe, highly immunogenic and should be able to recall rapidly the immunological memory upon the antigenic re-exposure. In this study vaccines made of full length recombinant NP and M2 of the H5N1 influenza A virus were entrapped either alone or together into liposome (L) made of phosphatidylcholine and cholesterol. The vaccines (L-NP, L-M2 or L-NP + M2) and mocks (L or PBS) were safe without causing any adverse reaction in the intramuscularly injected mice. They were readily immunogenic at a single dose and a recalled response could be detected within one day post booster. Cytokine and antibody data indicated that the vaccines induced a Th1 bias immune response. NP containing vaccines stimulated a marked increase of cytotoxic lymphocytes, i.e., CD8⁺, intracellular IFNγ⁺ cells, while M2 containing vaccines elicited good antibody response which neutralized infectivity of heterologous influenza viruses. Although the three vaccines elicited different immunological defense factors; nevertheless, they similarly and readily abrogated lung histopathology mediated by viruses belonging to different H5N1 clade/subclade and heterosubtypes including swine H1N1 and human H1N1/2009 viruses. They protected the vaccinated mice against lethal challenges with mouse adapted avian H5N1 virus. The liposome adjuvanted vaccines which demonstrated high protective efficacy in mice warrant testing further in a non-rodent model as well as in humans.     

Cardiovascular Morbidity and Mortality in High-Risk Populations: Epidemiology and Opportunities for Risk Reduction

Despite significant growth in the number of drug classes and individual agents available to combat various cardiovascular (CV) risk factors in clinical practice, the prevalence of these risk factors, including hypertension, diabetes mellitus, and obesity, has remained largely unchanged and in some cases has even increased during the past decade. CV risk factors remain consistently undertreated across the world, despite consensus guidelines issued by national and international health care organizations. Given the earlier onset of obesity and diabetes mellitus in many national populations, beginning from childhood, it is desirable to implement a range of lifestyle and pharmacologic interventions intended to modify CV risk factors while also improving glucose tolerance. Drugs that block the renin-angiotensin system are associated with reduced incidence of diabetes compared with other antihypertensive agents and should be considered mainstays of therapy for patients with hypertension who are at high risk for diabetes, CV disease, or both.