Collaborative Approach Toward Transplant Candidacy for Obese Patients with End-Stage Renal Disease

BACKGROUND

An elevated BMI is a major cause of transplant preclusion for patients with end-stage renal disease (ESRD). This phenomenon exacerbates existing socioeconomic and racial disparities and increases the economic burden of maintaining patients on dialysis. Metabolic bariatric surgery (MBS) in such patients is not widely available. Our center created a collaborative program to undergo weight loss surgery before obtaining a kidney transplant.

STUDY DESIGN

We studied the outcomes of these patients after MBS and transplant surgery. One hundred eighty-three patients with ESRD were referred to the bariatric team by the transplant team between January 2019 and June 2023. Of these, 36 patients underwent MBS (20 underwent Roux-en-Y gastric bypass and 16 underwent sleeve gastrectomy), and 10 underwent subsequent transplantation, with another 15 currently waitlisted. Both surgical teams shared resources, including dieticians, social workers, and a common database, for easy transition between teams.

RESULTS

The mean starting BMI for all referrals was 46.4 kg/m 2 and was 33.9 kg/m 2 at the time of transplant. The average number of hypertension medications decreased from 2 (range 2 to 4) presurgery to 1 (range 1 to 3) postsurgery. Similarly, hemoglobin A1C levels improved, with preoperative averages at 6.2 (range 5.4 to 7.6) and postoperative levels at 5.2 (range 4.6 to 5.8) All transplants are currently functioning, with a median creatinine of 1.5 (1.2 to 1.6) mg/dL (glomerular filtration rate 46 [36.3 to 71]).

CONCLUSIONS

A collaborative approach between bariatric and transplant surgery teams offers a pathway toward transplant for obese ESRD patients and potentially alleviates existing healthcare disparities. ESRD patients who undergo MBS have unique complications to be aware of. The improvement in comorbidities may lead to superior posttransplant outcomes.

A new approach to mentoring for research careers: the National Research Mentoring Network

Background and purpose

Effective mentorship is critical to the success of early stage investigators, and has been linked to enhanced mentee productivity, self-efficacy, and career satisfaction. The mission of the National Research Mentoring Network (NRMN) is to provide all trainees across the biomedical, behavioral, clinical, and social sciences with evidence-based mentorship and professional development programming that emphasizes the benefits and challenges of diversity, inclusivity, and culture within mentoring relationships, and more broadly the research workforce. The purpose of this paper is to describe the structure and activities of NRMN.

Key highlights

NRMN serves as a national training hub for mentors and mentees striving to improve their relationships by better aligning expectations, promoting professional development, maintaining effective communication, addressing equity and inclusion, assessing understanding, fostering independence, and cultivating ethical behavior. Training is offered in-person at institutions, regional training, or national meetings, as well as via synchronous and asynchronous platforms; the growing training demand is being met by a cadre of NRMN Master Facilitators. NRMN offers career stage-focused coaching models for grant writing, and other professional development programs. NRMN partners with diverse stakeholders from the NIH-sponsored Diversity Program Consortium (DPC), as well as organizations outside the DPC to work synergistically towards common diversity goals. NRMN offers a virtual portal to the Network and all NRMN program offerings for mentees and mentors across career development stages. NRMNet provides access to a wide array of mentoring experiences and resources including MyNRMN, Guided Virtual Mentorship Program, news, training calendar, videos, and workshops. National scale and sustainability are being addressed by NRMN "Coaches-in-Training" offerings for more senior researchers to implement coaching models across the nation. "Shark Tanks" provide intensive review and coaching for early career health disparities investigators, focusing on grant writing for graduate students, postdoctoral trainees, and junior faculty.

Implications

Partners from diverse perspectives are building the national capacity and sparking the institutional changes necessary to truly diversify and transform the biomedical research workforce. NRMN works to leverage resources towards the goals of sustainability, scalability, and expanded reach.

Application of a Quantum Cascade Laser for Time-Resolved, in Situ Probing of CH4/H2 and C2H2/H2 Gas Mixtures during Microwave Plasma Enhanced Chemical Vapor Deposition of Diamond

First illustrations of the utility of pulsed quantum cascade lasers for in situ probing of the chemistry prevailing in microwave plasma activated hydrocarbon/Ar/H2 gas mixtures used for diamond thin film growth are reported. CH4 and C2H2 molecules, and their interconversion, have been monitored by line-of-sight single pass absorption methods, as a function of process conditions (e.g., choice of input hydrocarbon (CH4 or C2H2), hydrocarbon mole fraction, total gas pressure, and applied microwave power). The observed trends can be rationalized, qualitatively, within the framework of the previously reported modeling of the gas-phase chemistry prevailing in hot filament activated hydrocarbon/H2 gas mixtures (Ashfold et al. Phys. Chem. Chem. Phys. 2001, 3, 3471). Column densities of vibrationally excited C2H2(v5=1) molecules at low input carbon fractions are shown to be far higher than expected on the basis of local thermodynamic equilibrium. The presence of vibrationally excited C2H2 molecules (C2H2(double dagger)) can be attributed to the exothermicity of the C2H3 + H <==> C2H2 + H2 elementary reaction within the overall multistep CH4 --> C2H2 conversion. Diagnostic methods that sample just C2H2(v=0) molecules thus run the risk of underestimating total C2H2 column densities in hydrocarbon/H2 mixtures operated under conditions where the production rate of C2H2(double dagger) molecules exceeds their vibrational relaxation (and thermal equilibration) rates.

Is postural tremor size controlled by interstitial potassium concentration in muscle?

OBJECTIVES

To determine whether factors associated with postural tremor operate by altering muscle interstitial K(+).

METHODS

An experimental approach was used to investigate the effects of procedures designed to increase or decrease interstitial K(+). Postural physiological tremor was measured by conventional means. Brief periods of ischaemic muscle activity were used to increase muscle interstitial K(+). Infusion of the beta(2) agonist terbutaline was used to decrease plasma (and interstitial) K(+). Blood samples were taken for the determination of plasma K(+).

RESULTS

Ischaemia rapidly reduced tremor size, but only when the muscle was active. The beta(2) agonist produced a slow and progressive rise in tremor size that was almost exactly mirrored by a slow and progressive decrease in plasma K(+).

CONCLUSIONS

Ischaemic reduction of postural tremor has been attributed to effects on muscle spindles or an unexplained effect on muscle. This study showed that ischaemia did not reduce tremor size unless there was accompanying muscular activity. An accumulation of K(+) in the interstitium of the ischaemic active muscle may blunt the response of the muscle and reduce its fusion frequency, so that the force output becomes less pulsatile and tremor size decreases. When a beta(2) agonist is infused, the rise in tremor mirrors the resultant decrease in plasma K(+). Decreased plasma K(+) reduces interstitial K(+) concentration and may produce greater muscular force fluctuation (more tremor). Many other factors that affect postural tremor size may exert their effect by altering plasma K(+) concentration, thereby changing the concentration of K(+) in the interstitial fluid.

The impact of therapeutic doses of paracetamol on serum total antioxidant capacity

INTRODUCTION

A link between regular paracetamol intake and asthma in adults has recently been postulated. Detoxification of paracetamol may deplete stores of glutathione, which is one of the major antioxidants present in the lung. A reduced source of glutathione in the lung may lead to increased oxidative damage to the epithelium and hence increased frequency and severity of asthma attacks in susceptible individuals.

AIM OF STUDY

This study aimed to determine whether regular intake of maximum therapeutic doses of paracetamol reduced serum antioxidant capacity in healthy volunteers.

METHODS

Fifteen young healthy volunteers (nine men, six women, mean age 21.3 years, range 19-32) took maximum therapeutic doses of paracetamol (1 g four times a day) for 14 days. On days 0 and 14 blood samples were taken at baseline and hourly for a period of 4 h following ingestion of 1 g paracetamol. Single venous blood samples were collected 1 h after ingestion of 1 g paracetamol on days 4, 7 and 10. Blood samples were analysed for serum paracetamol concentration and total antioxidant capacity.

RESULTS

Mean total antioxidant capacity was significantly reduced over the 3-h post-dosing on both days 0 and 14 (P < 0.01). The results from days 4, 7 and 10 showed a trend towards reduced antioxidant activity over time. On day 14 values were consistently lower compared with the corresponding times on day 0 (P < 0.01 at 0, 1, 3 and 4 h, P < 0.05 at 2 h).

CONCLUSIONS

Chronic ingestion of maximum therapeutic doses of paracetamol depletes serum antioxidant capacity in healthy volunteers in as few as 14 days, possibly by a reduction in glutathione. This may have implications for analgesic use in asthmatic individuals. Further studies are now required to assess the impact of paracetamol on antioxidant defences in the lung.

Fast, real-time spectrometer based on a pulsed quantum-cascade laser

We describe a mid-infrared spectrometer that is based on the combination of a multiple-pass absorption cell and a submicrosecond pulsed quantum-cascade laser. The spectrometer is capable of both making sensitive measurements and providing a real-time display of the spectral fingerprint of molecular vapors. For a cell with a path length of 9.6 m, dilution measurements made of the nu9 band transitions of 1,1-difluoroethylene indicate a sensitivity of 500 parts in 10(9), corresponding to a fractional absorbance of 4 x 10(-4).

Diode-pumped passively mode-locked Nd:KGd(WO(4))(2) laser with 1-W average output power

Continuous-wave passive mode locking of a diode-pumped Nd:KGd(WO(4))(2) laser is demonstrated. The use of a saturable Bragg reflector as the mode-locking element permits the generation of 6.3-ps pulses, assuming a sech(2) pulse shape. An output power of 1 W was obtained, which corresponds to a slope efficiency of 34.5%.

Use of the stable isotope (106)Cd for studying dietary cadmium absorption in humans

Hydroponically grown wheat was intrinsically labelled with the stable isotope 106cadmium (106Cd) and the flour made into a porridge. The abundance of the isotope in the porridge was approximately 30 times the natural abundance, but the total level of Cd in the porridge was 0.03 mg/kg fresh weight, which was the same as expected in a normal diet. Cadmium measurements were made using inductively coupled plasma-mass spectrometry (ICP-MS). The porridge was eaten at breakfast by adult and infant volunteers. Bulked faecal collections were analysed for unabsorbed Cd. Initial results suggest that the apparent absorption of Cd may be higher than 5% as commonly quoted, but longer faecal collection times may be necessary to confirm this.

Toxicity of mercury

A ruling by the European Union heralds the demise of those useful clinical instruments, the mercury thermometer and the mercury sphygmomanometer. The new laws have been passed because of worries about mercury poisoning. Yet you can drink metallic mercury and come to no harm. What does it all mean? There are three forms of mercury from a toxicological point of view: inorganic mercury salts; organic mercury compounds; and metallic mercury. Inorganic mercury salts are water soluble, irritate the gut, and cause severe kidney damage. Organic mercury compounds, which are fat soluble, can cross the blood brain barrier and cause neurological damage. Mercury metal poses two dangers. It can be vaporised: the vapour pressure at room temperature is about 100 times the safe amount, so poisoning can occur if mercury metal is spilled into crevices or cracks in the floorboards. Dentists are occasionally poisoned this way. Mercury easily crosses into the brain, and causes tremor, depression, and behavioural disturbances. A second danger from metallic mercury is that it is biotransformed into organic mercury, by bacteria at the bottom of lakes. This can be passed along the food chain and eventually to man. It was this process that led to the Japanese tragedy at Minimata Bay in the late 1950s when over 800 people were poisoned. It is the need to reduce mercury contamination of the environment which should encourage us to cut the usage of metallic mercury. However, much more metallic mercury is spilled as waste by the chemical industry than is dropped on the floor in the clinic.

Frequency stabilization of rare-earth-doped fiber lasers by use of 3 x 3 nonplanar fused-fiber couplers

We present a numerical analysis that indicates that a 3 x 3 nonplanar fused-fiber coupler can be used to inhibit longitudinal mode hops in a narrow linewidth unidirectional ring fiber laser. We also give preliminary experimental data that support our numerical analysis.

Longitudinal mode control of a narrow-linewidth fiber laser by use of the intrinsic birefringence of the fiber laser

We present preliminary experimental data that show that the intrinsic birefringence in a ring erbium fiber laser containing a length of standard communications-grade optical fiber can be used to inhibit longitudinal mode hops. Mode-hop-free operation for periods in excess of several hours is observed with resolution-limited linewidths of 240 kHz.

Tunable erbium fiber laser using a novel overlay bandpass filter

A unidirectional erbium fiber laser incorporating a novel LiNbO(3) overlay fiber-optic bandpass filter is demonstrated. By applying index-matching oils of different refractive indices to the surface of the overlay filter, we could tune the operating wavelength of the laser from 1531 to 1556 nm while maintaining a bandwidth of less than 0.2 nm (resolution limited). Output powers as high as 3 mW for 36 mW of pump power have been recorded.

Enhanced mode locking of color-center lasers

A significant enhancement in the mode locking of a KCl:Tl color-center laser has been observed when a length of optical fiber having positive group-velocity dispersion was incorporated within an external control cavity. Pulse durations of ~260 fsec were obtained by this method, representing a compression factor ~60x that with the colorcenter laser alone. Similar results have also been observed with an InGaAsP semiconductor diode amplifier as the nonlinear element within the control cavity.

Group-velocity-dispersion compensation of a passively mode-locked ring LiF:F(2)(+) color-center laser

By using an intracavity prism sequence to control group-velocity dispersion, pulses as short as 180 fsec have been generated near 850 nm from a passively mode-locked, traveling-wave LiF:F(2)(+) color-center laser.

Passively mode-locked color-center laser

Passive mode locking of a cw (chopped) color-center laser using a saturable-absorber polymethine cyanine dye is reported for the first time to our knowledge. By employing the dye IR 140 for passive mode locking, we have obtained stable-output trains of pulses from a LiF:F(2)(+) laser at wavelengths around 870 nm. When the technique of colliding-pulse mode locking was implemented in a ring-cavity configuration, pulses having durations as short as 390 fsec were generated.

Subpicosecond-pulse generation in a synchronously mode-locked ring color-center laser

Data are presented for the operation of a versatile color-center laser that permitted the generation of stable trains of subpicosecond pulses in a synchronously pumped ring configuration. With LiF:F(2)(+) as the gain medium, pulses having durations of 0.7 psec (Gaussian pulse shape assumed) were reliably obtained with average powers of 15-20 mW available in each of the two output beams. These pulse widths are more than a factor of 2 shorter than those obtained when this laser was configured with a standing-wave resonator.

Passive mode locking of a continuous-wave dye laser in the red-near-infrared spectral region

Passive mode locking of a cw Rhodamine 700 dye laser is reported for the first time to our knowledge. By using two saturable absorber dyes, DOTCI and HITCI, continuous-output trains of subpicosecond pulses have been obtained in the 727-740- and 762-778-nm spectral regions, respectively. By the addition of a fast-recovery-time dye (DCI) to the DOTCI saturable absorber, pulses as short as 350 fsec at 740 nm have been generated.

Collision behavior of young drivers. Impact of the change in the age of majority

A comparison of the number of collisions experienced by young male drivers in London, Ontario, before and after the reduction in the legal age for drinking and purchasing alcoholic beverages from 21 to 18, indicated that the change in the law led to an increase in the collision involvement of young drivers.