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Biomedical subjects

J B Shukla

Publications and source records attributed to J B Shukla.

14 recordsLinked to original sources
PubMed1991

Models for the effect of toxicant in single-species and predator-prey systems.

Models of single-species and predator-prey systems in a polluted closed environment are developed and partially analyzed. Three cases are considered: a single influx of toxicant, a constant influx of toxicant, and a periodic pollution of the environment. In the case of single-species growth we are able to determine some local and global dynamics. In the case of predator-prey systems, we investigate the existence of steady states for a small constant influx of toxicant.

Environmental Pollution↗
PubMed1989

Population diffusion in a two-patch environment.

A model of a single-species population diffusing in a two-patch environment is proposed. It is shown that there exists a positive, monotonic, continuous steady-state solution with continuous flux, in the cases of both reservoir and no-flux boundary conditions, that is asymptotically stable. In the case of patches with equal carrying capacities, it is shown that the uniform steady state is globally asymptotically stable.

Ecology↗
PubMed1989

Mucus transport in a miniaturized simulated cough machine: effect of constriction and serous layer simulant.

The transport of mucus gel simulant (MGS) in a constricted simulated cough machine, using blood plasma as a serous layer simulant (SLS), was investigated. MGS was prepared from locust bean gum solutions crosslinked with varying amounts of added borate to produce gels of varying spinnability (filance). The model trachea was a plexiglass channel of rectangular cross-section with the plane bottom surface. The upper surface included a sinusoidal protrusion which provided a flow convergence with minimum gaps of 6, 4 and 2 mm. Experiments for mucus transport were conducted for these minimum gaps, as well as for the non-convergent case (12 mm gap). Miniaturization of sample quantity was achieved by keeping the MGS layer depth constant (0.5 or 1 mm) but reducing the zone of loading from 13.4 cm to 1 cm, thus reducing the sample requirement to as little as 0.2 ml. MGS transport was determined as the minimum displacement of a line of marker dye placed in the MGS layer at the point of minimum constriction gap. It was shown that in all cases (dry as well as with SLS), MGS transport increased as the minimum constriction gap between the plane and the convergent top surface decreased. This increase was further enhanced if an SLS of lesser viscosity was used. It was also found that the transport of MGS increased as the depth of MGS layer increased or as the filance decreased in both non-constricted and constricted cases. The relationship between MGS transport and filance was maintained even in the presence of an SLS layer.

Airway Obstruction↗
PubMed1988

Effects of peristaltic and longitudinal wave motion of the channel wall on movement of micro-organisms: application to spermatozoa transport.

A mathematical model is presented to study the motion of the spermatozoa in the cervical canal by considering the transverse waves along its tail and the transverse and longitudinal motions of the cervical wall. In an attempt to control fertility by reducing the speed of sperm, the transverse waves have been considered in the direction opposite to the motion of the spermatozoa. It has been shown that by having appropriate transverse wave motion and longitudinal velocity, the sperm may not be able to move towards the oviduct even if it could continue to have its own propelling velocity. A particular case of the motion of a thin plane sheet in a channel under peristaltic motion of its walls has also been obtained and studied.

Female↗
PubMed1979

Isolation and characterization of a polyamine-peptide conjugate from human amniotic fluid.

Significant amounts of the diamine putrescine and the polyamines spermidine and spermine could be detected in human third-trimester amniotic fluid only after acid hydrolysis. This observation was interpreted to mean that these amines existed only in conjugated form in this biological fluid. Upon fractionation by ultrafiltration 90--10% of the putrescine was associated with the 1000--10 000 dalton fraction. Spermine was identified in this fraction and in a low-molecular weight fraction presumably representing acetylated derivatives. Spermidine was entirely associated with the 10 000--30 000 dalton fraction. The putrescine conjugate was purified to homogeneity by column chromatography on Biogels P10 and P6 followed by ion-exchange chromatography on DEAE-Sephadex A-25. Molecular weight by gel exclusion using peptide standards was estimated to be approx. 4600. The UV absorption spectrum of the putrescine conjugate conformed to that expected for a polypeptide. This putrescine conjugate contained 39 identified amino acids with a combined molecular weight of 4713. Putrescine was detectable by high pressure liquid chromatography only after acid hydrolysis of the conjugate. No other polyamines were detected in these hydrolyzates, nor were any polyamines demonstable in hydrolyzates of control peptides nor in pooled column washes. The identity of the putrescine determined by high pressure liquid chromatography was confirmed by a two-dimensional thin-layer chromatography method. These results establish the in vivo production of a putrescine--polypeptide conjugate in man. Such molecular species may constitute yet another metabolic pathway for polyamines or may reflect another mode of post-translational modification of polypeptide structure and function. The qualitative and quantitative analysis of polyamine conjugate in human aminotic fluid may prove to be useful in the detection of abnormalities in fetal development.

Amino Acids↗
PubMed1979

Polyamine conjugates and total polyamine concentrations in human amniotic fluid.

A study of the quantitative profile of polyamines in amniotic fluid from the 13th through the 40th week of gestation was undertaken. These experimental observations indicate the absence of free putrescine, spermidine and spermine throughout gestation. Quantities of acid-liberated putrescine, spermidine and spermine are highest in late first and late third trimester. Putrescine is associated with peptide or peptides of molecular weight 1000 to 10 000 throughout gestation. Spermidine is found in amniotic fluid covalently conjugated to peptide or peptides with molecular weight 10 000 to 30 000. Spermine appears to exist in amniotic fluid, both in the higher molecular weight fraction (1000 to 10 000) and as acetylated derivatives. The existance of polyamine conjugates is compatible with an in vivo function in the regulation of embryonic growth and development. Abnormalities in polymines conjugated to peptides or their concentration may be useful in the diagnosis of fetal maldevelopment.

Amniotic Fluid↗
PubMed1978

Polyamine compartmentalization in various human disease states.

Whole blood was separated into preparations of erythrocytes, mononuclear leukocytes, polymorphonuclear leukocytes, platelets and plasma. Each preparation was analyzed for the concentration of the polyamines putrescine, spermidine and spermine. This was done in 17 controls, 14 patients with psoriasis, four patients with hereditary elliptocytosis, two patients with chronic lymphocytic leukemia and one patient each with lung cancer, non-Hodgkin's lymphoma, sickle cell anemia with mild psoriasis, and progeria. In patients with elevated blood polyamine levels, absorption onto erythrocytes was relatively common, and the spermine/spermidine ratio was useful in localizing abnormalities and characterizing the nature of the polyamine alteration. Proliferative states were associated with elevated spermine/spermidine ratios relative to controls while this relationship was reversed in erythropathies such as hereditary elliptocytosis and sickle cell anemia.

Blood Platelets↗
PubMed1977

Cerebrospinal fluid polyamine monitoring in central nervous system leukemia.

High-pressure chromatographic analysis of cerebrospinal fluid utilizing the o-phthalaldehyde-fluorescent detection system allows the reproducible detection of acid-soluble polyamines in this extracellular fluid compartment. Measurements made by this method in childhood acute lymphocytic leukemia appear to correlate with the remission-relapse status of the patient. The sensitivity of this analytic technique may allow much earlier detection of central nervous system disease. Studies are presently under way in our laboratories to define the usefulness of this technique to monitor successful chemotherapy of leukemia patients.

Adolescent↗
PubMed1977

Bone marrow polyamines in children with acute leukemia as related to remission status, therapy, and cellularity of specimens.

Measurements of polyamines have potential practicality as biochemical markers of disease activity in adult cancer patients. On this basis, similar measurements were made in children with leukemia and solid tumors. Fluctuations in blood polyamine concentration were studied in relationship to chemotherapy schematics, cellularity and composition of blood and bone marrow specimens, and remission status of patients. Our results indicate that each of these factors may influence these determinations and consequently their clinical usefulness.

Adolescent↗
PubMed1976

Polyamine distribution in cellular compartments of blood and in aging erythrocytes.

Human blood was separated into pure preparations of erythrocytes, mononuclear leukocytes, polymorphonuclear leukocytes, platelets, and platelet free plasma. The mean concentrations of putrescine, spermidine, and spermine per 10(9) cells were found to be several orders of magnitude higher for leukocytes than erythrocytes. There was no significant difference between leukocyte types. Platelets and plasma had relatively low levels in proportion to the amounts contributed by erythrocytes and leukocytes to whole blood. Human erythrocytes were age-separated by density and the changes in polyamine concentrations in maturing erythrocytes were documented. There were highly significant statistical differences between young and old red blood cells for putrescine, spermidine and spermine. The clinical use of red blood cell polyamines as an indicator of the activity of the bone marrow in anemic states is suggested.

Adult↗
PubMed1976

Polyamine metabolism in cystic fibrosis.

Increased blood levels of spermidine and an increased spermidine/spermine ratio is documented in 31 patients with cystic fibrosis (CF). Some 29 percent of CF patients overlap with the control group. An abnormality of urinary free polyamines or their metabolic derivatives related to electrolyte transport, serum ciliostatic factors, and the autonomic nervous system are elaborated upon.

Animals↗
PubMed1975

Elevated spermidine and spermine levels in the blood of psoriasis patients.

Samples of blood, anticoagulated with EDTA, from 11 patients with psoriasis and 11 individuals without psoriasis were analyzed for their polyamine content. The average spermidine level in patients with psoriasis was approximately twice that of the controls and the average spermine level was three times that of the controls. The level of spermidine and spermine in the skin of two patients with psoriasis were significantly depressed as compared to those of controls.

Adolescent↗