The effect of minimum luminal nutrition on mucosal cellularity and immunity of the gut

Many catabolic patients can only consume small volumes of enteral nutrients. The aim of this study was to evaluate markers of cellularity and immunity in the small intestine of rats randomized to receive 6 days of parenteral nutrition, 25% enteral and 75% parenteral nutrition (i.e. minimum luminal nutrition) or enteral nutrition. The same glutamine-enriched solution was used for both parenteral and enteral nutrition. Enteral nutrition was associated with the least amount of jejunal atrophy (P<0.01), with the results from the minimum luminal nutrition group approximating those of the parenteral nutrition group. Parenteral nutrition was associated with the greatest number of CD2+ cells (P< 0.05) and the lowest CD4/CD8 cell ratio (P< 0.01) in the jejunal mucosa. In essence, we failed to demonstrate that there are any appreciable benefits associated with the enteral consumption of 25% of a nutrient load.     

Assessment of mitral regurgitation severity by Doppler color flow mapping of the vena contracta

BACKGROUND: Although Doppler color flow mapping is widely used to assess the severity of mitral regurgitation (MR), a simple, accurate, and quantitative marker of MR by color flow mapping remains elusive. We hypothesized that vena contracta width by color flow mapping would accurately predict the severity of MR. METHODS AND RESULTS: We studied 80 patients with MR. Vena contracta width was measured in multiple views with zoom mode and nonstandard angulation to optimize its visualization. Flow volumes across the left ventricular outflow tract and mitral annulus were calculated by pulsed-Doppler technique to determine regurgitant volume. Effective regurgitant orifice area was calculated by dividing the regurgitant volume by the continuous-wave Doppler velocity-time integral of the MR jet. The cause of MR was ischemia in 24, dilated cardiomyopathy in 34 mitral valve prolapse in 12, endocarditis in 2, rheumatic disease in 2, mitral annular calcification in 1, and uncertain in 5. Regurgitant volumes ranged from 2 to 191 mL. Regurgitant orifice area ranged from 0.01 to 1.47 cm2. Single-plane vena contracta width from the parasternal long-axis view correlated well with regurgitant volume (r = .85, SEE = 20 mL) and regurgitant orifice area (r = .86, SEE = 0.15 cm2). Biplane vena contracta width from apical views correlated well with regurgitant volume (r = .85, SEE = 19 mL) and regurgitant orifice area (r = .88, SEE = 0.14 cm2). A biplane vena contracta width > or = 0.5 cm was always associated with a regurgitant volume > 60 mL and a regurgitant orifice area > 0.4 cm2. A biplane vena contracta width < or = 0.3 cm predicted a regurgitant volume < 60 mL and a regurgitant orifice area < 0.4 cm2 in 24 of 29 patients. No other parameter, including jet area, left atrial size, pulmonary flow reversal, or semiquantitative MR grade, correlated significantly with regurgitant volume or regurgitant orifice area in a multivariate analysis. CONCLUSIONS: Our results demonstrate that careful color flow mapping of the vena contracta of the MR jet provides a simple quantitative assessment of MR that correlates well with quantitative Doppler techniques.     

Well number, length, and temperature dependence of efficiency andloss in InGaAsP-InP compressively strained MQW ridge waveguide lasers at1.3 μm

Experimental measurements of external differential efficiency on 0.7% compressively strained multiquantum-well (MQW) ridge waveguide lasers operating at 1.3 μm are presented. The lasers have the number of quantum wells (QW's) varying from 5 to 14 and cavity lengths ranging from 250 to 1000 μm and were measured over a temperature range of -50°C to 90°C. A phenomenological model is introduced which shows that over a range of design and operating conditions, the behavior of the external differential quantum efficiency can be entirely explained by intervalence band absorption (IVBA) It is also shown that outside this range IVBA alone is not sufficient to describe the behavior, indicating that current leakage becomes a significant factor. Ramifications of the IVBA contribution to the external differential quantum efficiency are investigated     

Trends disrupted—patent information in an era of change

Patent analysts predict trends in research and the business environment by studying the numbers and classifications of patents issued to companies around the world. Those attempts are often affected by the changes taking place in international treaties, governments, patent laws, patent classification systems, and corporate mergers and acquisitions. This paper describes some of the changes in the patent information environment that have disrupted the trends predicted by patent analyses in the past.     

The effect of varying barrier height on the operationalcharacteristics of 1.3-μm strained-layer MQW lasers

This paper presents an empirical study of the effects that barrier layer composition has on the operational characteristics of 1.3-μm-wavelength InGaAsP-InP multiquantum-well (MQW) strained-layer ridge-waveguide lasers. A systematic empirical investigation of how this design choice affects practical device operation was undertaken by examining threshold current, efficiency, and modal gain as a function of temperature in five different laser structures. The results of these studies indicate that small barrier heights improve device performance, despite the loss of electronic confinement in the shallow conduction band quantum wells. Indeed, it appears that carrier uniformity in the MQW structure may be improved by carrier redistribution due to thermal or tunneling effects, which in turn enhances the operation of the low barrier height structures     

Powerlessness and HIV prevention among people who trade sex for drugs (''strawberries'')

Agonistic analogs of GnRH have emerged as effective drugs in the treatment of pelvic pain associated with endometriosis. Iatrogenic hypoestrogenism is the fundamental mechanism through which GnRH agonists induce regression of the exquisitely estrogen-dependent endometriotic lesions. The decrease in bone mass consistently observed in women on long-term GnRH agonist treatment has prompted regulatory agencies such as the FDA to approve the use of these drugs for a maximum of six months in the treatment of endometriosis. The very high recurrence rate of pelvic symptomatology after the interruption of medical therapy underlines the importance of strategies aiming at improving the safety of effective long-term treatments. Data has recently become available suggesting the existence of an ideal range of circulating estradiol levels which would maintain a normal bone metabolism and still cause atrophy of endometriotic lesions. Add-back regimens including estrogen preparations have been therefore studied with variable results. In strict analogy, as oral progestins have been shown to improve bone mass in postmenopausal women, regimens employing progestin add-back have been proposed. Our review describes most of the currently published studies employing these and other substances in association with the commonly used GnRH agonists in patients with symptomatic endometriosis.     

Results concerning the bandwidth of subliminal channels

In conjunction with a six-month research program on computer security, cryptology and coding theory hosted by the Isaac Newton Institute of Mathematical Sciences, University of Cambridge, Cambridge, U.K., a Workshop on information hiding was held from May 30 through June 1, 1996. This workshop was devoted to all aspects of information hiding - other than the usual cryptographic concealment of content, including steganography, subliminal channels, fingerprinting, covert channels, etc. Two surprising results pertaining to subliminal channels were presented or grew out of presentations made at this workshop. One is of interest to the secure communications protocol designer concerned with denying the use of subliminal channels, while the other is important to the designer, or user, of subliminal channels. The first raises the question of whether the notion of a “subliminal-free” communication channel is an oxymoron, i.e., is it possible to force the bandwidth of the subliminal channel to be truly zero? The second forces a more precise formulation of a conjecture the author had made that the bandwidth of a subliminal channel is logarithmically limited if the transmitter is unwilling to trust the subliminal receiver unconditionally. Motivated by these results, this paper reexamines the fundamental questions of the bandwidth available for subliminal communication as a function of the trust the transmitter has in the subliminal receiver and of a logically sound interpretation of the term “subliminal-free”     

Synthesis and biological evaluation of potent, selective, hexapeptide CCK-A agonist anorectic agents

Cholecystokinin (CCK) is a 33-amino acid peptide with multiple functions in both the central nervous system (via CCK-B receptors) and the periphery (via CCK-A receptors). CCK mediation of satiety via the A-receptor subtype suggest a role for CCK in the management of obesity. The carboxy terminal octapeptide (CCK-8) is fully active in this regard, but is lacking in receptor selectivity, metabolic stability, and oral bioavailability. Inversion of the chirality of Asp7 in conjunction with N-methylation of Phe8 produces compound 5 which exhibits high affinity and 2100-fold selectivity for CCK-A receptors. Compound 6 (Hpa(SO3H)-Nle-Gly-Trp-Nle-MeAsp-Phe-NH2), derived from moving the N-methyl group from Phe to Asp, decreased CCK-B affinity substantially without affecting CCK-A affinity, giving a compound with 6600-fold selectivity for CCK-A receptors. These compounds inhibit food intake with nanomolar potency following intraperitoneal administration in fasted rats. In addition to greater potency, compound 6 produces weight loss in rats when administered over nine consecutive days. Intranasal administration of 6 potently inhibits feeding in beagle dogs. Compound 6 produces potent anorectic activity via the CCK-A receptor system.     

Preliminary risk-benefit assessment of mycophenolate mofetil in transplant rejection

Mycophenolate mofetil (the morpholinoethyl ester of mycophenolic acid) inhibits de novo purine synthesis via the inhibition of inosine monophosphate dehydrogenase. Its selective lymphocyte antiproliferative effects involve both T and B cells, preventing antibody formation. Mycophenolate mofetil has immuno-suppressive effects alone, but is used most commonly in combination with other immunosuppressants. Mycophenolate mofetil, in combination with cyclosporin and corticosteroids, has been studied in large, randomised clinical trials involving nearly 1500 renal allograft transplant recipients. These trials demonstrated that mycophenolate mofetil is significantly more effective in reducing treatment failure and acute rejection episodes than placebo or azathioprine. Additionally, mycophenolate mofetil may be able to reduce the occurrence of chronic rejection. Mycophenolate mofetil is relatively well tolerated. The most common adverse effect reported is gastrointestinal intolerance; haematological aberrations have also been noted. The reversible cytostatic action of mycophenolate mofetil allows for dose adjustment or discontinuation, preventing serious toxicity or an overly suppressed immune system. Cytomegalovirus tissue invasive disease and the development of malignancies are concerns that merit evaluation in long term follow-up studies. Mycophenolate mofetil does not cause the adverse effects typically associated with other commercially available immunosuppressant medications such as nephrotoxicity, hepatotoxicity, hypertension, nervous system disturbances, electrolyte abnormalities, skin disorders, hyperglycaemia, hyperuricaemia, hypercholesterolaemia, lipid disorders and structural bone loss. Based on preliminary information, a positive benefit-risk ratio has been demonstrated with the use of mycophenolate mofetil in the prophylaxis of rejection in cadaveric renal allograft transplantation. Data from studies in other types of organ transplants are promising, but are too limited to draw clear conclusions. Long term follow-up studies are required to confirm these observations. Although mycophenolate mofetil is expensive, the beneficial effects on the reduction of rejection, treatment failure and related expenses suggest that it is most likely to be cost effective.     

Public Perceptions and Actions towards Sustainable Groundwater Management in the Pacific Northwest Region,USA

A 50-question survey was developed by the land grant universities in the Pacific Northwest to document public awareness, aptitudes, attitudes and actions toward water issues in the states of Alaska, Idaho, Oregon and Washington, USA. Demographic data were also collected about the survey respondents. The statistically designed survey was completed by over 50% of the 1800 residents who were solicited for the study. The public consider clean groundwater a high priority issue. Survey respondents currently consider groundwater quality to be good; however, most people are unaware of groundwater quantity issues. In the last 5 years, a majority of survey respondents have taken voluntary actions both to protect groundwater quality and to conserve the use of this resource. People want the government to focus more attention on groundwater issues; however, they are unwilling to pay increased taxes to achieve this end. Based on this survey, the land grant universities need to increase groundwater education programmes for the public using television, radio, newspapers and the Internet rather than by the traditional workshop delivery methods.