Bioluminescence

Bioluminescence has evolved independently many times; thus the responsible genes are unrelated in bacteria, unicellular algae, coelenterates, beetles, fishes, and others. Chemically, all involve exergonic reactions of molecular oxygen with different substrates (luciferins) and enzymes (luciferases), resulting in photons of visible light (approximately 50 kcal). In addition to the structure of luciferan, several factors determine the color of the emissions, such as the amino acid sequence of the luciferase (as in beetles, for example) or the presence of accessory proteins, notably GFP, discovered in coelenterates and now used as a reporter of gene expression and a cellular marker. The mechanisms used to control the intensity and kinetics of luminescence, often emitted as flashes, also vary. Bioluminescence is credited with the discovery of how some bacteria, luminous or not, sense their density and regulate specific genes by chemical communication, as in the fascinating example of symbiosis between luminous bacteria and squid.

Metabolic studies on BMS-200475, a new antiviral compound active against hepatitis B virus

BMS-200475 was recently shown to have potent antiviral activity against hepatitis B virus (50% effective concentration = 3.7 nM; 50% cytotoxic concentration = 30 microM). In metabolic studies in both HepG2 and hepatitis B virus-transfected 2.2.15 human hepatoma cell lines, the metabolism was similar, the primary products being the di- and triphosphates. The accumulation of triphosphate was rapid and detectable down to a 5 nM concentration of added drug. When cells were labeled at 25 microM, the intracellular triphosphate concentration attained 30 pmol/10(6) cells ( approximately 30 microM). The intracellular half-life of the triphosphate was about 15 h. Compared with five other nucleoside analogs of medical interest (lamivudine, penciclovir, ganciclovir, acyclovir, and lobucavir), BMS-200475 was most efficiently phosphorylated to the triphosphate in HepG2 cells.

Intervening attenuation affects first-order statistical properties of ultrasound echo signals

Previous studies show that first-order statistical properties of ultrasound echo signals are related to the effective number of scatterers in the "resolution cell" of a pulse-echo ultrasound system. When the effective number of scatterers is large (~10 or more) this results in echo signals whose amplitude follows a Rayleigh distribution, with the RF echo signal obeying Gaussian statistics; deviation from Rayleigh or Gaussian statistics yields information on scatterer number densities. In this paper, the influence of the medium's attenuation on non-Gaussian properties of the echo signal is considered. Preferential attenuation of higher frequency components of a pulsed ultrasound beam effectively broadens the beam and increases the resolution cell size. Thus, the resultant non-Gaussian parameter for broad bandwidth excitation of the transducer depends not only on the scatterer number density but also on the attenuation in the medium. These effects can be reduced or eliminated by using narrow-band experiments.

Dynamic wave-front generation for the characterization and testing of optical systems

We describe a simple method for generating known optical aberrations dynamically, using a ferroelectric liquid-crystal spatial light modulator. Aberrations inherent in the optical system are measured and corrected, and as an example Kolmogorov turbulence is simulated for aperture sizes D/r(0) from 0 to 30, varying at frame rates up to 2.5 kHz. A measure of wave-front generation efficiency is introduced and is shown to be better than 86% for Kolmogorov phase screens with D/r(0) in the range from 0 to 30.

Liposome encapsulated prostaglandin E1 in erectile dysfunction: correlation between in vitro delivery through foreskin and efficacy in patients

OBJECTIVES

To test the delivery of prostaglandin E1 (PGE1) in novel transdermal liposomal formulations through foreskin and to determine whether there is a correlation between in vitro transdermal absorption and in vivo efficacy in patients with erectile dysfunction.

METHODS

The in vitro transdermal absorption of PGE1 through excised foreskin from liposomal formulations was tested in diffusion cells using radiolabeled drug. The in vivo studies were carried out on 5 patients (aged 54 to 70 years) in a double-blind, placebo-controlled fashion. The patients were treated topically on the penis with three different active formulations containing 0.05% PGE1 and a placebo at least 1 week apart. The change in systolic peak flow velocities in the cavernosal arteries after treatment was monitored by duplex color Doppler ultrasonography with spectral analysis every 15 minutes for 1 hour.

RESULTS

The permeability coefficient (Kp) of PGE1 from the three liposomal formulations tested was found to be 0. 10, 1.66, and 3.82 x 10(-4) cm/hr, respectively. Peak systolic flow velocities in the deep cavernosal arteries of patients increased significantly compared with preapplication values (0.05 < P < or = 0.1) after application of two of the transdermal liposomal PGE1 formulations tested (the two with the highest Kp). The highest mean peak systolic flow velocity was achieved at 45 minutes after application of the formulations. The most effective formulation in this study resulted in a sevenfold increase in mean flow velocity compared with baseline values.

CONCLUSIONS

Topical application of PGE1 in a novel transdermal liposomal delivery system can enhance penetration of the drug into the deep cavernosal bodies and increase peak systolic flow velocities in patients with erectile dysfunction. The transdermal flux and permeability of PGE1 measured in vitro correlate well with the color Doppler ultrasound results in patients. The efficacy of a formulation in the development process may be predicted from in vitro absorption studies.

Interactions of human hMSH2 with hMSH3 and hMSH2 with hMSH6: examination of mutations found in hereditary nonpolyposis colorectal cancer

Mutations in the human mismatch repair protein hMSH2 have been found to cosegregate with hereditary nonpolyposis colorectal cancer (HNPCC). Previous biochemical and physical studies have shown that hMSH2 forms specific mispair binding complexes with hMSH3 and hMSH6. We have further characterized these protein interactions by mapping the contact regions within the hMSH2-hMSH3 and the hMSH2-hMSH6 heterodimers. We demonstrate that there are at least two distinct interaction regions of hMSH2 with hMSH3 and hMSH2 with hMSH6. Interestingly, the interaction regions of hMSH2 with either hMSH3 or hMSH6 are identical and there is a coordinated linear orientation of these regions. We examined several missense alterations of hMSH2 found in HNPCC kindreds that are contained within the consensus interaction regions. None of these missense mutations displayed a defect in protein-protein interaction. These data support the notion that these HNPCC-associated mutations may affect some other function of the heterodimeric complexes than simply the static interaction of hMSH2 with hMSH3 or hMSH2 with hMSH6.

Primary care groups. View to a skill

Training is of critical importance to the successful development of PCGs. There are particular needs for developing strategic planning capacities. PCGs will need to understand and adopt many public health skills.

Real-time three-dimensional imaging of macroscopic structures

We describe an extremely simple method of obtaining optically sectioned images with conventional low-power imaging systems in real time. A single spatial frequency grid pattern is projected onto an object. Images taken at three spatial positions of the grid projection are processed to provide 3D images of macroscopic structures.

Examination of the two-dimensional pupil function in coherent scanning microscopes using spherical particles

The determination of the modulus of the pupil function in reflection acoustic and optical microscopy with the help of spherical particles is demonstrated. The theoretical examination shows that this method can give good results if the pupil function drops smoothly towards the edge. For a pupil with a sharp edge this technique can give the accurate pupil function only by imaging large spheres. The dependence of the accuracy of the method on the size of the spherical particle is analyzed. Numerical and experimental results obtained for the confocal scanning optical microscope and the scanning acoustic microscope are examined.

Cranberry extract inhibits low density lipoprotein oxidation

Cranberry juice consumption is often used for the treatment of urinary tract infections, but the effect of cranberry juice on heart disease has not been investigated. We evaluated how a cranberry extract containing 1,548 mg gallic acid equivalents/liter (initial pH=2.50) affected low density lipoprotein (LDL) oxidation induced by 10 micromolar cupric sulfate. When LDL oxidation took place in the presence of diluted cranberry extracts, the formation of thiobarbituric acid reactive substances (TBARS) and LDL electrophoretic mobility were reduced. LDL electrophoretic migration was also reduced when the cranberry extract had a pH of 7.00 prior to dilution. This study suggests that cranberry extracts have the ability to inhibit the oxidative modification of LDL particles.

Felodipine extended release versus conventional diuretic therapy for the treatment of systolic hypertension in elderly patients. The National Trial Group

OBJECTIVE

To compare 8 weeks of monotherapy using either felodipine extended release (ER) or a conventional diuretic therapy, triamterene/hydrochlorothiazide (HCTZ), in elderly patients with systolic hypertension.

DESIGN

Prospective, randomized, single-blind screening, double-blind treatment, parallel group comparison.

SETTING

Twenty-nine general and family practice sites across Canada.

PARTICIPANTS

Men and post-menopausal women aged 60 to 85 years, with mild to moderate primary systolic hypertension (systolic blood pressure > 160 mm Hg or blood pressure > 140/ > 90 mm Hg).

INTERVENTIONS

Daily doses of either felodipine ER (2.5 mg) or triamterene/HCTZ (25/12.5 mg) for 8 weeks. After the first 4 weeks, the patients who responded to the initial dosage (a reduction in systolic blood pressure of at least 15 mm Hg) or whose blood pressure was controlled on the dosage (systolic blood pressure < 140 mm Hg) continued to take the low dose. Among the others, the daily doses were doubled for the final 4 weeks.

OUTCOME MEASURES

Systolic blood pressure before beginning treatment and at the end of the study, as well as adverse events and results of heart rate measurement, clinical chemistry tests, electrocardiograms and physical examinations before and after therapy.

RESULTS

Sufficient data for analysis were obtained from 216 patients (86 men and 130 women). Mean seated blood pressure was reduced significantly in both the felodipine group (from 168/91 to 151/84 mm Hg) and the diuretic group (from 168/92 to 147/84 mm Hg). The difference in mean reductions in systolic blood pressure between the groups was 2.2 mm Hg (with a 95% confidence interval of-1.7 to 6.0 mm Hg), which was not significant. Clinical chemistry measurements taken before treatment and at the end of the study showed that more patients in the diuretic group developed abnormal values for blood urea nitrogen, uric acid and creatinine. Other changes were unremarkable. The incidence of adverse events was similar in both groups, but more patients in the felodipine group (9) than in the diuretic group (3) discontinued treatment owing to an adverse event.

CONCLUSIONS

Felodipine ER (2.5 to 5 mg daily) is as effective in reducing systolic blood pressure as triamterene/HCTZ (25/12.5 mg to 50/25 mg daily). More patients discontinued felodipine treatment than triamterene/HCTZ treatment owing to adverse events. However, patients receiving triamterene/HCTZ tended to have abnormal levels in clinical chemistry tests; these should be monitored.

Case report: management of significant incisor root resorption associated with maxillary canine impaction

Orthodontic and periodontic management of a patient with bilaterally impacted maxillary canines and advanced resorption of the adjacent lateral incisors is presented. In treating the patient, the affected laterals were retained and the canines were surgically exposed, then moved away from the roots of the laterals and into position in the arch. Alternative treatment strategies are discussed. Long-term follow-up evaluation revealed successful maintenance of the dentition and of periodontal health.

Identification of potential CD8+ T-cell epitopes of the 19 kDa and AhpC proteins from Mycobacterium tuberculosis. No evidence for CD8+ T-cell priming against the identified peptides after DNA-vaccination of mice

Mycobacterium tuberculosis is one of the major killers among infectious agents. It is of great importance to develop an efficient vaccine against M. tuberculosis since the only available vaccine, M. bovis-BCG, has a low efficacy. Furthermore, the emergence of multi-drug-resistant M. tuberculosis strains makes it difficult to cure the disease. CD8+ T cells have been implied to play an important role in protective immunity against M. tuberculosis. A good vaccination strategy for the induction of cytotoxic CD8+ T-cell responses is naked DNA-injection of eukaryotic expression vectors. The use of DNA-injection in an attempt to induce cytotoxic CD8+ T-cell responses against epitopes of the 19 kDa or AhpC proteins from M. tuberculosis in mice was studied. MHC class I binding assays, of peptides derived from these proteins, demonstrated the presence of potential CD8+ T-cell epitopes. However, CD8+ T-cell responses against the peptides after DNA-injection were not detected. Furthermore, no difference in the kinetics of bacterial clearance was observed in vaccinated versus unvaccinated animals, even though 19 kDa and AhpC specific antibodies were readily detected in the serum of vaccinated animals. Taken together these results suggest that the 19 kDa and AhpC genes are not good candidates for DNA vaccines against M. tuberculosis.

Method of obtaining optical sectioning by using structured light in a conventional microscope

We describe a simple method of obtaining optical sectioning in a conventional wide-field microscope by projecting a single-spatial-frequency grid pattern onto the object. Images taken at three spatial positions of the grid are processed in real time to produce optically sectioned images that are substantially similar to those obtained with confocal microscopes.

The use of signed English pictures to facilitate reading comprehension by deaf students

Many deaf students have severe difficulty acquiring literacy and developing reading comprehension beyond an elementary school level. This difficulty apparently results from a combination of perceptual, communication, instructional, linguistic, and experiential deficits. Although some deaf students develop a degree of signed English proficiency, this does not necessarily translate into reading proficiency. Recent studies examining the possible association between signed English pictures and comprehension of printed text present some support for facilitation of students' word recognition in a format combining those two elements. Whether this format enhances comprehension remains unclear from previous studies. The present study, involving 16 severely or profoundly deaf students across two reading-proficiency groups, examined whether the use of signed English pictures in association with printed text enhances students' reading comprehension. The study found that comprehension was significantly enhanced by the use of signed English reading books, with poorer readers deriving greater benefit than better readers. Practical implications of the findings are discussed.

The history of urology on postage stamps and cancellations

PURPOSE

Many important phases and personalities in the history of urology have been depicted on postage stamps, stationery and cancellations.

MATERIALS AND METHODS

The article gives a short recounting of several notable events that contributed to the development of urology as chronicled by philatelic material.

RESULTS

Beginning with the Egyptian papyri and ending with a recently acknowledged urologist, the historical survey covers uroscopy, lithotomy, lithotrity, anatomy, pathology, instruments, surgical techniques in urology, imaging techniques of the urinary tract, dialysis and renal transplantation. Personalities whose accomplishments have made a deep imprint in the history of urology, if honored on philatelic items, are described in this article.

CONCLUSIONS

Although the resulting picture does not necessarily present a continuity, it does emphasize certain peaks and high points in the evolution of this specialty.

Mutator phenotype in Msh2-deficient murine embryonic fibroblasts

Embryonic fibroblast cell lines were established from mice deficient, heterozygous, or proficient for Msh2, one of the three known DNA mismatch repair genes involved in hereditary nonpolyposis colon cancer (HNPCC). Cell lines were established by transfection of primary mouse embryo fibroblasts with E7 and Ras oncogenes or mutant p53. Spontaneously immortalized cells derived from the primary cultures were also studied. To determine whether these cells developed a mutator phenotype similar to that found in colon cancer cells deficient in mismatch repair, we measured mutation rates, microsatellite instability, and sensitivities to a range of DNA-damaging agents. The mutator phenotype detected in the E7 and Ras or mutant p53-immortalized Msh2-/- mouse cells was similar to that found in human mismatch repair-deficient colorectal carcinoma cell lines. Mutation rates to ouabain resistance were increased 8-12-fold relative to lines from Msh2+/+ mice, and microsatellite instability was detectable in 12-18% of subclones derived from the Msh2-/- line but was undetectable in subclones developed from the Msh2+/+ line. Furthermore, E7 and Ras or spontaneously immortalized Msh2-/- cells were significantly more resistant to the cytotoxic effects of 6-thioguanine relative to Msh2+/+ cells. In contrast, these lines showed various responses to UV light and cis-platinum, suggesting that mismatch repair deficiency was not the sole determinant for sensitivity to these DNA-damaging agents. Particular attention was paid to the properties of cells heterozygous for the Msh2 mutant gene, which would mimic the situation of an HNPCC carrier. However, our studies failed to reveal any properties of these cells that might provide a growth advantage or predispose them for the acquisition of further mutations. This observation is consistent with the model that inactivation of the wild-type Msh2 allele is a critical step for tumorigenesis in HNPCC patients.