Intervening in Symbiotic Cross-Kingdom Biofilm Interactions: a Binding Mechanism-Based Nonmicrobicidal Approach.

Early childhood caries is a severe oral disease that results in aggressive tooth decay. Particularly, a synergistic association between a fungus, Candida albicans, and a cariogenic bacterium, Streptococcus mutans, promotes the development of hard-to-remove and highly acidic biofilms, exacerbating the virulent damage. These interactions are largely mediated via glucosyltransferases (GtfB) binding to mannans on the cell wall of C. albicans Here, we present an enzymatic approach to target GtfB-mannan interactions in this cross-kingdom consortium using mannan-degrading exo- and endo-enzymes. These exo- and endo-enzymes are highly effective in reducing biofilm biomass without killing microorganisms, as well as alleviating the production of an acidic pH environment conducive to tooth decay. To corroborate these results, we present biophysical evidence using single-molecule atomic force microscopy, biofilm shearing, and enamel surface topography analyses. Data show a drastic decrease in binding forces of GtfB to C. albicans (∼15-fold reduction) following enzyme treatment. Furthermore, enzymatic activity disrupted biofilm mechanical stability and significantly reduced human tooth enamel demineralization without cytotoxic effects on gingival keratinocytes. Our results represent significant progress toward a novel nonbiocidal therapeutic intervention against pathogenic bacterial-fungal biofilms by targeting the interkingdom receptor-ligand binding interactions.IMPORTANCE Biofilm formation is a key virulence factor responsible for various infectious diseases. Particularly, interactions between a fungus, Candida albicans, and a bacterium, Streptococcus mutans, have been known to play important roles in the pathogenesis of dental caries. Although some antimicrobials have been applied to treat fungal-involved biofilm-associated diseases, these often lack targeting polymicrobial interactions. Furthermore, these may not be appropriate for preventive measures because these antimicrobials may disrupt ecological microbiota and/or induce the prevalence of drug resistance over time. By specifically targeting the interaction mechanism whereby mannoproteins on the C. albicans surface mediate the cross-kingdom interaction, we demonstrated that mannoprotein-degrading enzymes can effectively disrupt biofilm interactions without microbiocidal effects or causing cytotoxicity to human cells. This suggests a potential application as a targeted approach for intervening a pathogenic cross-kingdom biofilm associated with a costly and unresolved oral disease.

Cross-Kingdom Cell-to-Cell Interactions in Cariogenic Biofilm Initiation.

Candida albicans is known to form polymicrobial biofilms with various Streptococcus spp., including mitis and mutans group streptococci. Streptococcus gordonii (mitis group) has been shown to bind avidly to C. albicans hyphae via direct cell-to-cell interaction, while the cariogenic pathogen Streptococcus mutans (mutans group) interacts with the fungal cells via extracellular glucans. However, the biophysical properties of these cross-kingdom interactions at the single-cell level during the early stage of biofilm formation remain understudied. Here, we examined the binding forces between S. mutans (or S. gordonii) and C. albicans in the presence and absence of in situ glucans on the fungal surface using single-cell atomic force microscopy and their influence on biofilm initiation and subsequent development under cariogenic conditions. The data show that S. gordonii binding force to the C. albicans surface is significantly higher than that ofS. mutans to the fungal surface (~2-fold). However, S. mutans binding forces are dramatically enhanced when the C. albicans cell surface is locally coated with extracellular glucans (~6-fold vs. uncoated C. albicans), which vastly exceeds the forces between S. gordonii andC. albicans. The enhanced binding affinity of S. mutans to glucan-coated C. albicans resulted in a larger structure during early biofilm initiation compared to S. gordonii-C. albicans biofilms. Ultimately, this resulted in S. mutans dominance composition in the 3-species biofilm model under cariogenic conditions. This study provides a novel biophysical aspect of Candida-streptococcal interaction whereby extracellular glucans may selectively favor S. mutans binding interactions with C. albicans during cariogenic biofilm development.

Rapid Semisynthesis of Acetylated and Sumoylated Histone Analogs.

The density and diversity of posttranslational modifications (PTMs) observed in histone proteins typically limit their purification to homogeneity from biological sources. Access to quantities of uniformly modified histones is, however, critical for investigating the downstream effects of histone PTMs on chromatin-templated processes. Therefore, a number of semisynthetic methodologies have been developed to generate histones bearing precisely defined PTMs or close analogs thereof. In this chapter, we present two optimized and rapid strategies for generating functional analogs of site-specifically acetylated and sumoylated histones. First, we describe a convergent strategy to site-specifically attach the small ubiquitin-like modifier-3 (SUMO-3) protein to the site of Lys12 in histone H4 by means of a disulfide linkage. We then describe the generation of thialysine analogs of histone H3 acetylated at Lys14 or Lys56, using thiol-ene coupling chemistry. Both strategies afford multimilligram quantities of uniformly modified histones that are easily incorporated into mononucleosomes and nucleosome arrays for biophysical and biochemical investigations. These methods are readily extendable to any desired sites in the four core nucleosomal histones and their variant forms.

WPW and preexcitation syndromes.

Wolff-Parkinson-White syndrome is a disorder characterized by presence of an accessory pathway which predisposes patients to tachyarrhythmias and sudden death. Among patients with WPW syndrome, atrioventricular reentrant tachycardia (AVRT) is the most common arrhythmia, accounting for 95% of re-entrant tachycardias. It has been estimated that one-third of patients with WPW syndrome have atrial fibrillation (AF). AF is a potentially life-threatening arrhythmia. If an accessory pathway has a short anterograde refractory period, then rapid repetitive conduction to the ventricles during AF can result in a rapid ventricular response with subsequent degeneration to ventricular fibrillation (VF). The accessory pathway may be located anywhere along the atrioventricular valve Most of the patients are young and do not have structural heart disease hence it is important to risk stratify these patients so as to prevent the sudden death. Management of asymptomatic patients with WPW syndrome has always remained controversial Catheter ablation of accessory pathways has become an established mode of therapy for symptomatic patients and asymptomatic patients employed in high-risk professions.

Conscious sedation as an anaesthetic technique in patients undergoing nonthoracotomy placement of automatic implantable cardioverter defibrillator: an initial experience.

Six adult patients with life threatening recurrent ventricular arrhythmias who underwent non- thoracotomy placement of automatic implantable cardioverter defibrillator under conscious sedation are reported. Our clinical experience, patient satisfaction, recovery profile, complications and cardiologist perception about the technique of conscious sedation is presented and discussed.

Cerebral venous thrombosis in a patient of paroxysmal nocturnal haemoglobinuria following aplastic anaemia.

A young lady who had aplastic anaemia presented for cerebral venous thrombosis after five years of follow up. She was diagnosed to have paroxysmal nocturnal haemoglobinuria. She had received immunosuppressive therapy with methylprednisolone, cyclosporine-A, anti-lymphocyte globulin, danazol and pregnenolone. The relation between aplastic anaemia, paroxysmal nocturnal haemoglobinuria and cerebral venous thrombosis is discussed. The role of immunosuppressive therapy for aplastic anaemia in causation of paroxysmal nocturnal haemoglobinuria is reviewed.

False-positive exercise stress electrocardiogram due to accessory pathway in the absence of manifest preexcitation.

False-positive exercise testing in patients with an accessory pathway has been described only in patients with manifest preexcitation during exercise. We describe a patient in whom marked ST-segment changes were seen during an exercise test in the absence of any preexcitation of the QRS complexes. The role of the accessory pathway in producing the ST changes was reaffirmed by absence of this abnormality following catheter ablation of the accessory pathway.

Transcatheter device closure of ventricular septal defects: immediate results and intermediate-term follow-up.

BACKGROUND: Transcatheter closure is an accepted mode of treatment in selected cases of congenital heart disease. Lately, this technology has been applied to closure of ventricular septal defect (VSD). METHODS AND RESULTS: We performed percutaneous transcatheter closure of VSD in 30 patients. The location of VSD was perimembranous in 28 patients and muscular trabecular in 2. Two (7%) patients also had left ventricular-right atrial communication. There were 17 male subjects and 13 female subjects, with an age range of 5. 5 to 33 years (mean +/- SD, 12.9 +/- 5.7; median 12.2). The diameter of VSD ranged from 3 to 8 mm (mean +/- SD 4.7 +/- 1.3; median 4.5). In 5 (17%) patients, the pulmonary to systemic blood flow (Qp/Qs) was >/=2.1 (range 2.0 to 2.6). The defect was at least 6 or 8 mm from the aortic valve in patients in whom a 12- or 17-mm Rashkind double umbrella device was deployed, respectively. In 1 patient, the defect was closed with a detachable stainless steel coil, size 8 mm, with 4 loops (8 x 4). The devices were successfully deployed in 87% of patients. In 6 (20%) patients, the procedure had to be repeated primarily because of the use of undersized umbrella deices. Unsuccessful deployment of the device occurred in 4 (13%) patients. In one of these procedures, the coil embolized to the left pulmonary artery, and it was successfully retrieved. A minimal residual shunt seen as a thin streak on transthoracic color flow mapping persisted in 8 (30%) patients, which remained unchanged over a follow-up period of 5 to 28 (17.1 +/- 6.4) months. Both patients with left ventricular/right atrial communication showed complete abolition of the shunt. No patient developed new-onset aortic or tricuspid regurgitation or intravascular hemolysis. At follow-up, no patient had developed infective endocarditis, bundle branch block, or late valvular insufficiency. CONCLUSIONS: Transcatheter closure is safe and efficacious in selected cases of perimembranous and muscular VSD.

Transcatheter closure of secundum atrial septal defect with atrial septal defect occlusion system (ASDOS): initial experience and short-term follow-up.

Transcatheter closure of secundum atrial septal defect is a well known alternative to surgery. It was attempted in seven patients (age range 7-34 years, mean 20.1 +/- 6.5 years) with the double umbrella nitinol device (ASDOS, Dr. Ing Osypka, Germany). The interatrial septal anatomy and blood flow were examined by transthoracic and multiplane transoesophageal echocardiography. The size of atrial septal defect varied from 1.25-2.4 cm (mean 1.75 +/- 0.3 cm), minimal septal rim 0.5-1.0 cm (mean 0.75 +/- 0.20 cm), and Qp/Qs 1.6-3.2:1 (mean 2.4 +/- 0.6). One patient had an atrial septal defect following surgery for left atrial myxoma. The procedure which involved the use of monorail system for deployment of device under transoesophageal echocardiography guidance, was successful in six (86%) of the seven patients. The size of the implanted device ranged from 30-45 mm. In two patients, the right atrial umbrella had to be oversized in comparison to the left atrial umbrella for stability and adequate occlusion of the defect. The patient in whom the procedure failed had a defect size of 1.7 cm, with minimal septal rim (anterosuperior) of 5 mm; however, the device could be easily retrieved. Immediately after and at follow-up of one year, transoesophageal echocardiography-guided colour flow mapping revealed complete abolition of left-to-right shunt in five (83%) of the six patients. One patient had a small residual flow at the posterior rim of the defect; none had atrioventricular valve regurgitation. Although the procedure is complex, it is safe with the advantage of excellent control on the monorail system for proper positioning, repositioning and, if required, retrieval of the device.

Adolescence: myths and misconceptions.

PIP: Adolescence is the period of physical and psychological growth between childhood and adulthood. The author is a practicing obstetrician and gynecologist in New Delhi. Over the course of her medical career, she has identified many myths and misconceptions about adolescents and adolescence. With regard to male adolescents, masturbation-related myths may be the most frequently harbored. Male adolescents have a hormone-driven need to have sexual intercourse, frequently. Masturbation is a healthy, no-cost way to relieve sexual tension. There is neither need to pay a prostitute nor fear of contracting a sexually transmitted disease. A young man can masturbate virtually whenever he wants. Despite the guilt and misinformation implanted by adults that masturbation causes weakness, boys masturbate rather frequently. Also contrary to popular myth, the nocturnal emissions which may result in growing boys as a result of sexual excitement during a dream are completely normal and no reason for concern. Further, boys should not worry about penis size, for, when erect, they all work just fine. People grow at different rates. Menstruation starts when 17% of a woman's body weight is fat. The onset of menstruation may therefore start earlier in well-fed girls compared to in girls who are more lean. The frequency and duration of menses are not constant. Menstrual irregularity therefore does not necessarily mean that a young woman is pregnant or that professional medical treatment is required. Breasts, like penises, serve their intended function irrespective of size. The hymen is a membrane at the opening of the vagina. It may have a hole in the center or the side for the escape of menstrual blood. There are myths that an intact hymen is indicative of virginity, the hymen should be intact until marriage, and the first sexual experience should be painful for a woman. The hymen is elastic and even some prostitutes have been found to have intact hymens. The hymen also may tear due to a fall, cycling, or horse riding. Furthermore, myths exist that kissing can cause pregnancy or AIDS, homosexuality is abnormal and incompatible with heterosexual relationships later in life, and different positions of coitus may adversely affect physical health. Adolescents sorely need sources of sound scientific factual information to dispel their myths.^ieng

Contraceptives: choice for the millions?

PIP: India adds each year the population of Sub-Saharan Africa to the earth. User based factors determining the type of contraceptive that is used most often in a country are sociocultural practices including religion, literacy, women's status and their role in decision making, men's status, misconceptions, and convenience of use. Service related factors include knowledge and skill of the provider, attitude of the provider, accessibility of family planning services, cost of the contraceptives, and quality of services. The government, nongovernmental organizations, and the pharmaceutical firms tend to be the contraceptive researchers and suppliers. The mass media are used to disseminate information on contraceptives. They often relay sensational reports about a contraceptive method that results in its reduced use. Temporary or spacing family planning methods include natural family planning methods, condoms, IUDs, oral contraceptives, implants, and injectables, spermicides and vaginal barriers. The natural family planning methods are sexual abstinence, especially in the postpartum period; rhythm or calendar method; and coitus interruptus. The most cost-effective method is also the most popular method--sexual sterilization. Even though female sterilization is more difficult to perform than vasectomy, it is more common than vasectomy. Contraception should become a people's movement rather than be forced upon the people. People should insist on good quality, affordable contraceptive services as their basic right.^ieng

High altitude dives from 7000 to 14,200 feet in the Himalayas.

Indian Navy divers carried out no-decompression dives at altitudes of 7000 to 14,200 ft (2134-4328 m) in the Nilgiris and Himalayas from May to July 1988. Seventy-eight dives on air and 22 dives on oxygen were carried out at various altitudes. The final dives were at Lake Pangong Tso (4328 m) in Ladakh, Himalayas, to a maximum of 140 feet of sea water (fsw) [42.6 meters of sea water (msw)] equivalent ocean depth in minimum water temperature of 2 degrees C. Oxygen diving at 14,200 ft (4328 m) was not successful. Aspects considered were altitude adaptation, diminished air pressure diving, hypothermia, and remote area survival. Depths at altitude were converted to depths at sea level and were applied to the Royal Navy air tables. Altitude-related manifestations, hypoxia, hypothermia, suspected oxygen toxicity, and equipment failure were observed. It is concluded that stress is due to effects of altitude and cold on man and equipment, as well as changes in diving procedures when diving at high altitudes. Equivalent air depths when applied to Royal Navy tables could be considered a safe method for diving at altitudes.