Temperature stability of static and dynamic properties of 1.55 µm quantum dot lasers.

Static and dynamic properties of InP-based 1.55 µm quantum dot (QD) lasers were investigated. Due to the reduced size inhomogeneity and a high dot density of the newest generation of 1.55 µm QD gain materials, ridge waveguide lasers (RWG) exhibit improved temperature stability and record-high modulation characteristics. Detailed results are shown for the temperature dependence of static properties including threshold current, voltage-current characteristics, external differential efficiency and emission wavelength. Similarly, small and large signal modulations were found to have only minor dependences on temperature. Moreover, we show the impact of the active region design and the cavity length on the temperature stability. Measurements were performed in pulsed and continuous wave operation. High characteristic temperatures for the threshold current were obtained with T0 values of 144 K (15 - 60 °C), 101 K (60 - 110 °C) and 70 K up to 180 °C for a 900-µm-long RWG laser comprising 8 QD layers. The slope efficiency in these lasers is nearly independent of temperature showing a T1 value of more than 900 K up to 110 °C. Due to the high modal gain, lasers with a cavity length of 340 µm reached new record modulation bandwidths of 17.5 GHz at 20 °C and 9 GHz at 80 °C, respectively. These lasers were modulated at 26 GBit/s in the non-return to zero format at 80 °C and at 25 GBaud using a four-level pulse amplitude format at 21 °C.

Static and dynamic characteristics of an InAs/InP quantum-dot optical amplifier operating at high temperatures.

We report on high quality InAs/InP quantum dot optical amplifiers for the 1550 nm wavelength range operating over a wide temperature range of 25 to 100 °C. A temperature dependent shift of the peak gain wavelength at a rate of 0.78 nm/K is observed. Consequently, two possible modes of operation are performed for a systematic device characterization over the entire temperature range. In the first mode, the signal wavelength is tuned to always match the peak gain wavelength while in the second mode, the signal wavelength is kept constant as the gain spectrum shifts with the temperature. Static characteristics, such as gain spectra and saturation levels, as well as dynamical properties, are presented. Distortion-less amplification of a single 28 Gbit/s signal and cross-talk free amplification of two channels, detuned by 2 nm, were demonstrated over the entire temperature range.

Over-the-Scope Clip (OTSC) System for Sleeve Gastrectomy Leaks.

BACKGROUND: Laparoscopic sleeve gastrectomy (LSG) is currently being widely accepted for its role in the treatment of morbid obesity. Staple-line leakage is one of the most reported complications found in 0.5-7 % of the population, in which the Over-the-Scope Clip (OTSC) (Ovesco Endoscopy, Tübingen, Germany), a novel device, is employed. We present our experience with this system in LSG leaks. METHODS: A retrospective analysis of prospectively collected data from patients with LSG leakage was performed, and these patients were treated with the OTSC system. Efficiency was defined as complete oral nutrition without any evidence of additional leakage. RESULTS: Overall, 26 patients underwent endoscopic OTSC treatment. The median age was 39 years (range 26-60), and 12 were male patients (46.15 %). The mean body mass index (BMI) was 42.89 kg/m(2), and 10 patients (38.46 %) came from a revisional bariatric procedure (SRVG or LAGB). Twenty-two patients (84.61 %) had upper staple-line leaks (near the GEJ), and the remaining 4 (15.38 %) had lower antral leaks. Number of endoscopy sessions ranged from 2 to 7 (median 3). There were five failures: 2 of them had an antral leak, and the remaining 3 had an upper staple-line leak. Twenty-one (80.76 %) leaks were successfully treated within 32 days' median time till complete oral nutrition was attained (range 14-70). CONCLUSIONS: The success rate was high with the OTSC system, and it is concluded to be a safe and effective treatment for LSG leaks.

Androgen Receptor CAG Repeat Length in Relation to Phenotype Among Females with Nonclassical 21-Hydroxylase Deficiency.

Nonclassical 21-hydroxylase deficiency (NC21OHD) manifests with various degrees of post natal virilization. The length of CAG repeats of the androgen receptor gene (AR) is inversely correlated to activity of the human androgen receptor (AR) and affects phenotype of several androgen-dependent disorders. The aim of the study was to investigate the associations between CAG repeat length and the phenotype of females with NC21OHD. CAG repeat length and AR inactivation were assessed in females with NC21OHD, and related to their clinical presentation. CAG repeat length and AR inactivation were assessed in 119 females with NC21OHD. Biallelic mean (BAM) of the CAG repeat length and the weighted BAM (WBAM) were related to various clinical parameters. Age at diagnosis and age of menarche positively correlated with BAM (r=0.22, p=0.02, and r=0.23, p=0.01, respectively). A shorter (<25) BAM was associated with younger age at diagnosis (14.8 vs. 21.4 years, p<0.01), at adrenarche (8.1 vs. 10.2 years, p<0.01) and gonadarche (9.9 vs. 11.2 years, p<0.01), and higher corrected height standard deviation score at diagnosis (0.77 vs. 0.15, p=0.01). Precocious pubarche and precocious puberty were more frequent in these with the shorter BAM. Results of WBAM were similar. The CAG repeat length of the AR gene contributes to the clinical diversity of the phenotype in females with NC21OHD.

[Androgen receptor polymorphism in relation to medical conditions characterized by hyper/hypoandrogenism].

An androgen receptor (AR) is a transcription factor consisting of four functional regions. The transactivation region contains a highly polymorphic area characterized by a variable number of CAG trinucleotide repeats encoding a polyglutamine tract. Several in vitro studies demonstrated a negative linear relation between the lengths of CAG repeats and relative AR transactivations. Numerous clinical studies then sought associations between the described polymorphism and clinical parameters of various medical conditions characterized by hyper/hypoandrogenism. In this article, we describe some of those interesting associations. We believe such links should be investigated in any medical condition involving androgens as a key element in its pathogenesis.

Prevalence and molecular characterization of Hepatozoon canis in dogs from urban and rural areas in Southeast Brazil.

The objective of this survey was to investigate the prevalence of Hepatozoon infection in dogs in the rural and urban areas of Uberlândia, Brazil by PCR and molecular characterization. DNA was obtained from blood samples collected from 346 local dogs from both genders and various ages. Seventeen PCR products from positive blood samples of urban dogs and 13 from the rural dogs were sequenced. Partial sequences of the 18S rRNA gene indicated that all 30 dogs were infected with Hepatozoon canis similar in sequence to H. canis from southern Europe. Four local dog sequences were submitted to GenBank (accessions JN835188; KF692038; KF692039; KF692040). This study indicates that H. canis is the cause of canine hepatozoonosis in Uberlândia and that infection is similarly widespread in rural and urban dogs.

Prevalence of Babesia microti-like infection in red foxes (Vulpes vulpes) from Portugal.

The prevalence of piroplasm (order Piroplasmida) infection was assessed in blood and bone marrow samples from 91 red foxes (Vulpes vulpes) from northern, central and southern Portugal by means of molecular methods. PCR for the 18S rRNA gene of Babesia spp. followed by sequencing revealed 63 foxes positive for the Babesia microti-like piroplasm (syn. Theileria annae) (69.2%; 95% confidence interval [CI]: 58.7-78.5%) and one fox positive for Babesia canis (1.1%; 95% CI: 0.0-6.0%). Positivity to the B. microti-like piroplasm or B. canis in 43 blood samples (83.7%) was significantly higher (p<0.001) than in 43 paired bone marrow samples (20.9%). There were no statistically significant differences in the prevalence of infection between genders (p=0.219) or age groups (<2 years vs. ≥ 2 years) (p=1.0). This is the first report of the B. microti-like piroplasm in foxes from Portugal as well as the first report on detection by PCR and genotyping of B. canis in a red fox worldwide. A natural cycle of the B. microti-like piroplasm is suggested in red fox populations based on the high prevalence of the protozoan. Red foxes might be a reservoir of the B. microti-like piroplasm and a source of infection to dogs.

Molecular detection of Ehrlichia canis, Anaplasma bovis, Anaplasma platys, Candidatus Midichloria mitochondrii and Babesia canis vogeli in ticks from Israel.

: Ticks are vectors of important pathogens of human and animals. Therefore, their microbial carriage capacity is constantly being investigated. The aim of this study was to characterize the diversity of domestic animal pathogens in ticks collected from vegetation and the ground, from different parts of Israel. Non-engorged questing adult ticks were collected from 13 localities. A total of 1196 ticks in 131 pools-83 pools of Rhipicephalus turanicus and 48 of Rhipicephalus sanguineus (with two to ten ticks per pool)-were included in this study. In addition, 13 single free-roaming Hyalomma spp. ticks were collected. Screening by molecular techniques revealed the presence of Ehrlichia canis, Anaplasma platys, Anaplasma bovis and Babesia canis vogeli DNA in R. turanicus ticks. E. canis, A. bovis, B. canis vogeli and Candidatus Midichloria mitochondrii DNA sequences were detected in R. sanguineus ticks. Candidatus Midichloria mitochondrii DNA was also detected in Hyalomma spp. ticks. Neither Hepatozoon spp. nor Bartonella spp. DNA was detected in any of the ticks examined. This study describes the first detection of E. canis in the tick R. turanicus, which may serve as a vector of this canine pathogen; E. canis was the most common pathogen detected in the collected questing ticks. It also describes the first detection of A. bovis and Candidatus Midichloria mitochondrii in Israel. To the best of the author's knowledge, this is the first report describing the detection of DNA of the latter two pathogens in R. sanguineus, and of A. bovis in R. turanicus.

Theoretical evaluation of a four-band fiber-optic radiometer.

A theoretical simulation of a four-band fiber-optic radiometric technique is presented. This is a technique for remote, noncontact temperature measurement of a sample near room temperature, under conditions of unknown emissivity and ambient temperature. A realistic setup of a broadband IR detector, a set of three filters, an IR fiber, and a MATLAB software package for the calculations, is simulated in two steps: a calibration process and a measurement process. The results of the simulation show the limitations and advantages of the four-band radiometric technique and show the expected resolution of the sample temperature and emissivity and of the ambient temperature measurement. The theoretical resolution of the sample temperature measured by the four-band radiometric setup comes close to the resolution achieved in an equivalent single-band radiometric setup. The four-band method has an additional advantage of making it possible to calculate values of emissivity and ambient temperature.

Temperature controlled CO(2) laser welding of soft tissues: urinary bladder welding in different animal models (rats, rabbits, and cats).

BACKGROUND AND OBJECTIVE: Laser welding of tissues is a method of closure of surgical incisions that, in principle, may have advantages over conventional closure methods. It is a noncontact technique that introduces no foreign body, the closure is continuous and watertight, and the procedure is faster and requires less skill to master. However, in practice, there have been difficulties in obtaining strong and reliable welding. We assumed that the quality of the weld depends on the ability to monitor and control the surface temperature of the welded zone during the procedure. Our objective was to develop a "smart" fiberoptic laser system for controlled temperature welding. STUDY DESIGN/MATERIALS AND METHODS: We have developed a welding system based on a CO(2) laser and on infrared transmitting AgClBr fibers. This fiberoptic system plays a double role: transmitting laser power for tissue heating and noncontact (radiometric) temperature monitoring and control. The "true" temperature of the heated tissue was determined by using an improved calibration method. We carried out long-studies of CO(2) laser welding of urinary bladders in various animal models. Cystotomies were performed on the animals, and complete closure of the bladder was obtained with a surface temperature of 55 +/- 5 degrees C at the welding site. RESULTS: In early experiments on 31 rats, the success rate was 73%. In later experiments with 10 rabbits and 3 cats, there was an 80% and a 100% success rate, respectively. CONCLUSION: The success rate in these preliminary experiments and the quality of the weld, as determined histologically, demonstrate that temperature controlled CO(2) laser welding can produce effective welding of tissues. The fiberoptic system can be adapted for endoscopic laser welding.

Endotracheal tolazoline: pharmacokinetics and pharmacodynamics in dogs.

Tolazoline is a potent vasodilator of both arteries and veins and has a powerful effect on the pulmonary vasculature, reducing hypoxic pulmonary vasoconstriction and lowering pulmonary artery pressure. Intravenous tolazoline lowers the mean pulmonary arterial pressure and resistance and increases the cardiac index when given to infants with persistent pulmonary hypertension of the newborn (PPHN). Endotracheally administered tolazoline decreases mean pulmonary arterial pressure and pulmonary vascular resistance, and improves oxygenation without the harmful decline in systemic arterial pressure. The purpose of our study was to examine the pharmacokinetic and pharmacodynamic characteristics of endotracheal tolazoline in order to determine the relationship between endotracheal tolazoline administration, plasma concentration and its effects on the cardiovascular and respiratory systems. Tolazoline was administered endotracheally to 7 newborn dogs, and its serum concentration and the haemodynamic parameters were monitored for 270 min post-delivery. Results are expressed as median and quartiles. It was found that 15 s after dosing, tolazoline plasma concentrations started to increase significantly above baseline levels, reaching a maximum of 2.64 (1.36; 13.16) microg/ml. The extent of tolazoline absorption was 305 (148;453) microg/ min/ml. The volume of distribution was 3.4 (1.6;7.4) 1/kg. The total body clearance was 12.1 (10.9;23.9) ml/min/kg and the elimination half-life was 225 (171;303) min. Endotracheal tolazoline produced an initial short-lived decrease in mean blood pressure in all the dogs, but thereafter the blood pressure increased gradually above baseline levels. Immediately following endotracheal tolazoline significant tachycardia developed, peaking at 90 min. Subsequently, the heart rate gradually decreased and stabilized at values above baseline for 200 min. A single endotracheal dose of tolazoline is effectively absorbed and produces measurable pharmacological effects. Determining the optimal endotracheal dose of tolazoline in the clinical setting requires additional evaluation.

Pharmacokinetics of endobronchial tolazoline administration in dogs.

Tolazoline is a potent vasodilator of arteries and veins and has a powerful effect on the pulmonary vasculature, reducing hypoxic pulmonary vasoconstriction and lowering pulmonary artery pressure. Intravenous tolazoline lowers the mean pulmonary arterial pressure and resistance and increases the cardiac index when given to infants with persistent pulmonary hypertension (PPHN). Endotracheally administered tolazoline decreases mean pulmonary arterial pressure and pulmonary vascular resistance, and improves oxygenation without the harmful decline in the systemic arterial pressure. The purpose of our study was to examine the pharmacokinetic and pharmacodynamic characteristics of endobronchial tolazoline to determine the relationship between endobronchial tolazoline administration, plasma concentration, and its effects on the cardiovascular and respiratory systems. Tolazoline was administered endobronchially to seven dogs, and its serum concentration and the hemodynamic parameters were monitored for 270 min postdelivery. It was found that 15 sec after dosing, tolazoline plasma concentrations started to increase significantly above baseline levels, reaching a maximum of 9.3+/-8.0 microg x mL(-1) The volume of distribution was 1657+/-321 mL x kg(-1) after 1 2.4+/-1 6.6 min. The extent of tolazoline absorption was 319+/-38 microg x min(-1) mL(-1). The total body clearance was 10.9 +/-4.8 mL x min(-1) x Kg(-1) and the elimination half-life was 156+/-81 min. Endobronchial tolazoline produced an initial short-lived decrease in the mean blood pressure in all the dogs, but thereafter the blood pressure increased gradually above baseline levels. Immediately following endobronchial tolazoline a significant tachycardia developed, peaking at 90 min. Subsequently, the heart rate gradually decreased and stabilized at values above baseline for 200 min. We conclude that an endobronchial bolus dose of tolazoline is effectively absorbed, produces measurable pharmacological effects, and may be beneficial in the therapy of persistent pulmonary hypertension of the newborn.

[Atypical infantile hypertrophic pyloric stenosis].

Infantile hypertrophic pyloric stenosis (IHPS) is the most common reason for nonbilious vomiting in infants. Its cause is unknown. Hypertrophy of pyloric muscle can progress after birth and reach complete gastric outlet obstruction. Usually symptoms start after the age of 3 weeks. In the past diagnosis was based on history of projectile, nonbilious vomiting and palpation of a pyloric mass. Greater awareness of IHPS and increased use of imaging modalities, mainly abdominal ultrasonography, have resulted in a change in the clinical condition at presentation. The length of illness before admission has decreased and weight loss, dehydration and metabolic abnormalities have become less common. We describe an atypical clinical manifestation of IHPS: bilious vomiting. This atypical presentation may be due to earlier diagnosis.

Fiber-optic pulsed photothermal radiometry for fast surface-temperature measurements.

Temperature measurement based on pulsed photothermal radiometry is described. In this technique a body is irradiated by a laser pulse and its temperature is inferred from the shape of the emitted photothermal-signal curve. A prototypical system based on a pulsed CO(2) laser, an IR detector, and IR-transmitting silver halide optical fibers was constructed and used to evaluate the feasibility of this technique. An important feature of the technique is that changes in sample emissivity or geometric factors do not introduce errors in the temperature determination. Theory, simulation, and experimental results are given and discussed.

Development of polyclonal antibodies for detection of aflatoxigenic molds involving culture filtrate and chimeric proteins expressed in Escherichia coli.

Polyclonal antibodies (PAb) were raised against an aflatoxigenic strain of Aspergillus parasiticus by using two different sources for antibody elicitation: (i) filtrate of a culture on which the fungus had been grown (ii) and two chimeric proteins, expressed in Escherichia coli as separate products, of the genes ver-1 and apa-2, which are involved in aflatoxin biosynthesis. The gene products were amplified by PCR, and each was cloned into the E. coli expression vector pGEX2T. Upon induction, the bacteria overexpressed 38- and 33-kDa chimeric proteins corresponding to the N-terminal domains of the genes ver-1 and apa-2, respectively. The chimeric proteins were isolated and affinity purified for use as antigens. The specificity of the raised antibodies was examined by enzyme-linked immunosorbent assay (ELISA). The PAbs raised against the culture filtrate reacted with all the species of Aspergillus and Penicillium tested but not with Fusarium species or corn gain. However, the PAbs elicited against the chimeric proteins were highly specific, showing significantly higher ELISA absorbance values (A405) against A. parasiticus and A. flavus than against the other fungi tested and the corn grain. The approach of utilizing gene products associated with aflatoxin biosynthesis for antibody production therefore appears to be feasible. Such a multiantibody system combined with the PCR technique, could provide a useful tool for the rapid, sensitive, and accurate detection of aflatoxin producers present in grains and foods.

Connectors, splices, and couplers for infrared transmitting optical fibers.

Connectors, splices, and couplers are widely used in silica optical fiber systems. Until now they have not been developed for mid-infrared fibers, in spite of the recognized need for such elements in many applications such as spectroscopy, radiometry, and heterodyne detection. We describe the construction and the optical and mechanical properties of such optical components for infrared transmitting silver halide optical fibers.

Temperature-controlled CO2 laser tissue welding of ocular tissues.

Lasers can be used for binding tissues by welding, but the clinical application of this method has been limited by the difficulties in defining and maintaining the optimal conditions. Fiberoptic radiometry allows accurate remote temperature measurements for control of laser tissue welding. We evaluated the use of a temperature-controlled tissue welding system to close corneal and corneoscleral wounds. Eighty ex vivo bovine eyes were used for the determination of welding parameters optimal for corneal wound closure. A 4 mm central corneal cut was closed with use of a CO2 laser (600 mw, 0.9 mm spot size), with tissue temperatures ranging from 45-70 degrees C and welding time ranging from 1-30 seconds. Wound strength was measured as burst pressure of the sealed wound. The welding parameters found to cause the strongest wound binding were used to weld a limbal incision of 4 mm in 10 adult albino rabbits. The fellow eye of each animal was used as a control, and the same wound was closed with one 10/0 mersilen suture. Two animals were killed immediately after the procedure, and the eyes were sent for histologic examination. Eight rabbits were followed for 1 month. Clinical examination and refraction were done 1 day, 1 week, 2 weeks, and 1 month after the procedure. Corneal topographic evaluations were done 1 week after the procedure. After 1 month the animals were killed and the eyes were examined histologically. The optimal results of wound binding by laser welding in the enucleated bovine eyes were achieved with 55-60 degrees C and at a welding time of 12-20 seconds. At these parameters the burst pressure of corneal wounds was 70 mm Hg. All laser-welded limbal wounds in the rabbits were tightly closed at the end of procedure and during the follow-up period. The refractive results after laser welding were equal to those of the controlled suture-closed wound. Laser tissue welding combined with tissue temperature monitoring can be used to close corneal wounds.

Detection of aflatoxigenic molds in grains by PCR.

Aflatoxins are carcinogenic metabolites produced by several members of the Aspergillus flavus group in grains and floods. Three genes, ver-1, omt-1, and apa-2, coding for key enzymes and a regulatory factor in aflatoxin biosynthesis, respectively, have been identified, and their DNA sequences have been published. In the present study, three primer pairs, each complementing the coding portion of one of the genes, were generated. DNA extracted from mycelia of five Aspergillus species, four Penicillium species, and two Fusarium species was used as PCR template for each of the primer pairs. DNA extracted from peanut, corn, and three insect species commonly found in stored grains was also tested. Positive results (DNA amplification) were achieved only with DNA of the aflatoxigenic molds Aspergillus parasiticus and A. flavus in all three primer pairs. The detection limit of the PCR was determined by using the primer pairs complementing the omt-1 and ver-1 genes. Sterile corn flour was inoculated separately with six different molds, each at several spore concentrations. Positive results were obtained only after a 24-h incubation in enriched media, with extracts of corn inoculated with A. parasiticus or A. flavus, even at the lowest spore concentration applied (10(2) spores per g). No DNA spores per g). It is concluded that genes involved in the aflatoxin biosynthetic pathway may form the basis for an accurate, sensitive, and specific detection system, using PCR, for aflatoxigenic strains in grains and foods.

NADPH diaphorase activity in mammalian retinas is modulated by the state of visual adaptation.

NADPH diaphorase histochemistry is commonly used to identify cells containing nitric oxide synthase (NOS), the enzyme catalyzing the production of nitric oxide from L-arginine. NADPH diaphorase activity and NOS immunostaining was demonstrated in different cells of the vertebrate retina; photoreceptors, horizontal cells, amacrine cells, ganglion cells, and Müller cells. However, the physiological role of nitric oxide (NO) in the retina has yet to be elucidated. In this study, we tested the assumption that NADPH diaphorase activity in the retinas of rabbits and rats depended on the state of visual adaptation. In the rabbit, light adaptation enhanced NADPH diaphorase activity in amacrine cells and practically eliminated it in horizontal cells. Dark adaptation induced the opposite effects; the NADPH diaphorase activity was reduced in amacrine cells and enhanced in horizontal cells. Retinas from eyes that were injected intravitreally with L-glutamate exhibited a pattern of NADPH diaphorase activity that was similar to that seen in dark-adapted retinas. In rats, the NADPH diaphorase activity of amacrine and horizontal cells exhibited adaptation dependency similar to that of the rabbit retina. But, the most pronounced effect of dark adaptation in the rat's retina was an enhancement of NADPH diaphorase activity in Müller cells, especially of the endfoot region. Assuming that NADPH diaphorase activity is a marker for NOS, these findings suggest that NO production in the mammalian retina is modulated by the level of ambient illumination and support the notion that NO plays a physiological role in the retina.