Modelling of urea hydrolysis kinetics using genetic algorithm coupled artificial neural networks in urease immobilized magnetite nanoparticles.

The presence of urea in runoff from fertilized soil could be contributing to the growth of dangerous blooms. Enzymatic urea hydrolysis is a well-known outstanding process that, when integrated with nanotechnology, would be much more efficient. This research provides a novel perspective on magnetic nanobiocatalysts that reduce diffusion barriers in effective urea hydrolysis. Surprisingly, the model developed with the use of a Genetic Algorithm (GA) and an Artificial Neural Network (ANN) demonstrated that the system's diffusion restrictions were reduced. In order to forecast accurate outputs using artificial intelligence (AI), a neural network with one hidden layer and 20 neurons was built utilizing multilayer feed-forward network and showed highest output (diffusion co-efficient) with least mean square error (MSE). The diffusion coefficients of free urease, urease immobilized onto porous MNs (U-aMNs), and nanobiocatalyst, i.e. urease immobilized onto surface modified MNs (U-MNß), were 1.9 × 10-17, 12.62 × 10-16, and 15.48 × 10-16 cm2/min, respectively. These results revealed that the addition of Chitosan to the surface of MNs had a considerable impact on enzyme dispersion. The decrease in Damkohler number (Da) from 2.37 ± 0.26 for U-aMNs to 2.19 ± 0.11 for U-MNß suggested a beneficial effect in overcoming diffusion constraints. Pseudo-first order and pseudo-second order models were used to analyze urea uptake kinetics, with the former model offering the best fit to the system, with R2 values that were much closer to unity.

The role of orbital ultrasonography in distinguishing papilledema from pseudopapilledema.

PURPOSE: To determine the sensitivity and specificity of orbital ultrasonography in distinguishing papilledema from pseudopapilledema in adult patients. METHODS: The records of all adult patients referred to the neuro-ophthalmology service who underwent orbital ultrasonography for the evaluation of suspected papilledema were reviewed. The details of history, ophthalmologic examination, and results of ancillary testing including orbital ultrasonography, MRI, and lumbar puncture were recorded. Results of orbital ultrasonography were correlated with the final diagnosis of papilledema or pseudopapilledema on the basis of the clinical impression of the neuro-ophthalmologist. Ultrasound was considered positive when the optic nerve sheath diameter was ≥3.3 mm along with a positive 30° test. RESULTS: The sensitivity of orbital ultrasonography for detection of papilledema was 90% (CI: 80.2-99.3%) and the specificity in detecting pseudopapilledema was 79% (CI: 67.7-90.7%). CONCLUSIONS: Orbital ultrasonography is a rapid and noninvasive test that is highly sensitive, but less specific in differentiating papilledema from pseudopapilledema in adult patients, and can be useful in guiding further management of patients in whom the diagnosis is initially uncertain.

A randomized, double-blind study of the effect of olestra on disease activity in patients with quiescent inflammatory bowel disease. Olestra in IBD Study Group.

PURPOSE: To determine the effects of olestra, a zero-calorie fat substitute that is neither digested nor absorbed, on the well-being and disease state of persons with chronic inflammatory bowel disease (IBD) in remission. PATIENTS AND METHODS: Eighty-nine patients with mild to moderate ulcerative colitis (n = 43) or Crohn's disease (n = 46) in remission, with a history of disease of 2 years or longer, were enrolled in this prospective study from nine private practices, three university-based medical centers, and one Veterans Administration medical center in the United States. Forty-four patients were randomly assigned to receive olestra and 45 to receive triglycerides in chips or cookies daily for 4 weeks. At Week 4, patients were classified as in remission, worsened, or relapsed according to an investigator's global assessment based on sigmoidoscopy (for ulcerative colitis) or the Crohn's disease activity index, laboratory findings, and clinical course. RESULTS: At Week 4, the olestra and triglyceride groups did not differ significantly with respect to the percentages of patients who relapsed (P = 0.494; difference = 2.4%; upper 95% CL = 8.8%) or with respect to the percentages of patients who experienced any worsening of their symptoms (P = 0.630; difference = 0.2%; upper 95% CL = 13.3%). Of evaluable patients, 90% (37 of 41) given olestra remained in remission with no worsening, compared with 90% (38 of 42) given triglycerides. Gastrointestinal symptoms were comparable between the treatment groups, and there were no treatment-related laboratory abnormalities. Six patients were excluded from analysis for reasons unrelated to treatment. CONCLUSION: Olestra did not affect the activity of quiescent mild to moderate IBD.

The effect of olestra on systemic levels of oral contraceptives.

The effect of olestra, a nonabsorbable, noncaloric fat replacement, on the absorption and efficacy of a highly lipophilic oral contraceptive was investigated in a double-blind, placebo-controlled crossover study with 28 women. Subjects consumed 18 gm/day olestra for 28 days while taking an oral contraceptive containing 300 micrograms of norgestrel and 30 micrograms ethinyl estradiol (Lo/Ovral-28). Blood taken on days 12 to 14 of the treatment cycles was analyzed for ethinyl estradiol and norgestrel. There was no statistically significant difference in time to attain maximum concentration, maximum concentration, or area under the concentration-time curve between the olestra and placebo treatments for either drug component. Measurements of serum progesterone indicated that olestra ingestion did not reduce efficacy as indicated by ovulation. The data show that ingestion of 18 gm/day olestra did not affect the absorption or efficacy of the highly lipophilic oral contraceptive.

Chromosome ends in Drosophila without telomeric DNA sequences.

We have recovered terminal chromosome deletions of the X chromosome of Drosophila [Df(1)RT; RT = receding tips] that break in various positions of the yellow gene (y) region and delete all distal DNA sequences. Terminal DNA fragments are heterogeneous in length. Molecular cloning and sequencing of the terminal DNA fragments revealed that the broken ends of the deleted chromosomes do not carry any telomeric DNA sequences, yet the broken chromatids do not fuse to one another. Moreover, we confirmed by sequence analysis of 49 independently cloned terminal DNA fragments from two RT lines collected at different times that they lose DNA sequences from their distal ends at a rate of 70-75 base pairs per fly generation. We calculate that the rate of loss from these ends is consistent with the removal of an octanucleotide RNA primer at each round of DNA replication in the germ line.

Further light on the tyramine test in depression.

In studies of post-partum women, the oral tyramine loading test is shown to be of predictive value in identifying those subjects with a lifetime history of depressive illness. The cause of the decreased output of conjugated tyramine, after tyramine ingestion, is still unclear. Some possible mechanisms have been under scrutiny.

A predictive study of post-partum depression: some predisposing characteristics.

Postnatal depression was investigated by the antenatal screening of a sample of women for factors that might be predictive of later disturbance. The women were assessed when they were 36 weeks pregnant on anxiety, hostility, and locus of control. Predictions were tested by assessing depression 6 weeks after birth. Both high anxiety and high hostility were positively associated with postnatal depression. Intropunitiveness was not significantly related to subsequent depression. The most depressed women were those who had been the more extrapunitive as well as the more hostile. Women who perceived themselves as less in control of their lives were likely to rate high on depression postnatally, as were younger women. There were indications that some women may have been experiencing depression before the birth. Depression was not significantly associated with parity, gravidity, race, social class or marital status.

Decreased urinary output of tyramine and its metabolites in depression.

Despite dramatic clinical improvement in about one-third of a group of severely depressed, medication-resistant patients one year after modified leucotomy, their relative decrease in conjugated and free tyramine output after an oral tyramine load remained unchanged and abnormal. Whilst a direct deficit in intestinal tyramine-conjugating ability still needs to be finally ruled out, this appears most compatible with a deficit due to bodily metabolic failure, perhaps a deficit in membrane transport which could be an essential aspect of the depressive illness syndrome. Attention is drawn to a similar defect in migraine. The two illnesses may represent a common predisposition which an appropriate triggering mechanism may transform to the florid disease. Biochemical detection of such vulnerability may have important diagnostic and predictive significance.

Is there an increase in monoamine-oxidase activity in depressive illness?

In a group of depressed patients who had either been treated with or considered suitable for monoamine oxidase (M.A.O.) inhibitor therapy, a highly significant decrease in conjugated tyramine output was observed after an oral tyramine load compared with normal controls. However, there was no difference in conjugated isoprenaline output between the two groups after isoprenaline ingestion, even though this amine is almost solely metabolised by what is likely to be the same conjugation mechanism. Whilst some explanation in terms of altered gut motility is conceivable, it seems more likely that the apparent deficit in tyramine conjugation in depression represents an increase in functional M.A.O. activity. Consequently, this enzyme would metabolise a greater proportion of available amine, causing a proportionately large decrease in the smaller conjugate pool.