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Biomedical subjects

J L Nelson

Publications and source records attributed to J L Nelson.

At least 127 records · Page 7Linked to original sources
PubMed1987

Esophageal manometry in 95 healthy adult volunteers. Variability of pressures with age and frequency of "abnormal" contractions.

UNLABELLED: Although esophageal manometry is widely used in clinical practice, the normal range of esophageal contraction parameters is poorly defined. Therefore, 95 healthy volunteers (mean age: 43 years; range 22-79 years) were studied with a low-compliance infusion system and 4.5-mm-diameter catheter. All subjects were given 10 wet swallows (5 cc H2O) and 38 subjects also were given 10 dry swallows. RESULTS: Amplitude, but not duration, was greater (P less than 0.05) after wet compared to dry swallows. Both distal mean contractile amplitude and duration of wet swallows significantly increased with age and peaked in the fifties. Double-peaked waves frequently occurred after both wet (11.3%) and dry (18.1%) swallows, but triple-peaked waves were rare (less than 1%). Nonperistaltic contractions were more common (P less than 0.001) after dry compared to wet swallows (18.1% vs 4.1%). This difference resulted from frequent simultaneous contractions after dry swallows (12.6% vs 0.4%). CONCLUSIONS: Distal esophageal contractile amplitude and duration after wet swallows increases with age. Triple-peaked waves and wet-swallow-induced simultaneous contractions should suggest an esophageal motility disorder. Double-peaked waves are a common variant of normal. Dry swallows have little use in the current evaluation of esophageal peristalsis.

Adult↗
PubMed1987

Partial purification and some biochemical properties of neonatal rat cutaneous glutathione S-transferases.

1. Previous studies have demonstrated the presence of glutathione S-transferases in the skin of rodents and humans. This study represents the first attempt to purify cytosolic glutathione S-transferases from skin of 3-day-old rats. 2. A partial purification of the enzyme was achieved by a two-step procedure: affinity chromatography followed by HPLC. Two peaks, one major (P-1) and one minor (P-2), were resolved by HPLC containing about 82% and 10% of the recovered activity, respectively. 3. The major form exhibited an overall purification of about 2270-fold with a specific activity of about 73 mumoles/min/mg protein towards 1-chloro-2,4-dinitrobenzene. 4. The kinetic data for P-1 yielded mean Km values of 2.39 mM for 1-chloro-2,4-dinitrobenzene and 0.72 mM for reduced glutathione, while the respective average Vmax values were found to be 212 and 101 mumoles/min/mg protein. 5. Significantly inhibition of enzyme activity was noted in the presence of 0.2 mM HgCl2, 0.63 microM 1.2-naphthoquinone, 1.0 microM triphenyltin chloride, and 12.5 microM 17 beta-estradiol-3-sulfate.

Animals↗
PubMed1987

Burn-induced alterations in feeding, energy expenditure, and brain amine neurotransmitters in rats.

A 30% body surface area, open-flame, full-thickness burn of adult rats induced a 4-day period of anorexia that was followed by hyperphagia beginning on postburn day 10. The hyperphagic burned rats also exhibited increased resting energy expenditure and no gain in body weight, suggesting hypermetabolism. Plasma levels of immunoreactive insulin and albumin were decreased in both groups of burned rats; immunoreactive pancreatic glucagon concentrations were elevated only in the anorectic burned rats. Plasma levels of epinephrine were elevated in the hyperphagic burned rats. In the brain, dopamine metabolism appeared to be increased in the corpus striatum, nucleus accumbens, and amygdala of anorectic burned rats; norepinephrine levels were elevated in the hypothalamus and nucleus accumbens of the hyperphagic-hypermetabolic rats. These data indicate that this animal model of major burn trauma exhibits anorexia, hyperphagia, catabolism, and hypermetabolism. Furthermore, elevated dopamine metabolism appears to be associated with the anorexia, while the hyperphagia-hypermetabolism may be mediated by norepinephrine.

Animals↗
PubMed1987

Acivicin reduces tumor growth during total parenteral nutrition (TPN).

Glutamine appears to be an important substrate for tumor growth. Since tumor growth rate may be stimulated by total parenteral nutrition (TPN), we investigated the effect of the glutamine antimetabolite, acivicin, on methylcholanthrene sarcoma growth in rats maintained on TPN or on rat chow. Acivicin treatment significantly reduced tumor growth by 67% in rats receiving TPN and by 71% in rats maintained on chow. Carcass weights were significantly increased by TPN in both acivicin-treated and saline solution-treated tumor-bearing rats. Tumor-carcass ratios were significantly decreased in both groups of acivicin-treated tumor-bearing rats. Acivicin treatment or a similar approach may therefore be useful for stabilizing tumor growth in patients receiving TPN.

Animals↗
PubMed1986

Antagonism of stress-induced analgesia by quaternary naloxone.

Both naloxone hydrochloride and the quaternary compound, naloxone methylbromide, significantly reduced antinociception elicited by 90 s of continuous footshock. Peripheral specificity of quaternary naloxone was demonstrated by its lack of antagonism of morphine analgesia. These results suggest that a significant portion of the antinociception elicited by these parameters of footshock and assessed by tail-flick procedures in rats is due to the activation of peripheral endorphins.

Analgesia↗
PubMed1986

Peroxidase activity in the mouse uterus, placenta and fetus during pregnancy.

Changes in peroxidase activity during pregnancy were examined in CD-1 mice. Peroxidase activity was measured with guaiacol as the substrate in uterine extracts of nonpregnant mice and in uterine, placental, and fetal extracts of pregnant mice on days 9, 12, 14, 16, and 18 of gestation. Uterine peroxidase activity in nonpregnant mice was high, but declined logarithmically to only 0.2% by day 18 of pregnancy. In contrast to this decline, a concomitant 50-fold logarithmic increase in fetal peroxidase activity was observed between day 12 and 18. Activity in placental extracts did not change significantly throughout the gestational period examined. These results suggest that membrane bound peroxidase in mouse uterus and fetus undergoes major shifts during pregnancy.

Animals↗
PubMed1985

Retinal vasculitis associated with autoantibodies to Sjögren's syndrome A antigen.

Severe retinal vasculitis caused by a systemic lupus-like illness developed in two patients with distinctive clinical and immunologic characteristics. Both patients were young women with mild systemic disease and autoantibodies directed against a protein-ribonucleic acid complex termed the Sjögren's syndrome A antigen (SSA). One patient had no antibodies to nuclear antigens on conventional testing, and the other had a low-titer antinuclear antibody test. At the time of onset of retinal arteriolitis, neither patient had an exacerbation of multisystem disease or serologic activity. Despite oral and parenteral corticosteroids, cytotoxic agents, and panretinal photocoagulation, both patients suffered progressive irreversible retinal ischemia, optic disk and retinal neovascularization, vitreous hemorrhage traction retinal detachment, and anterior segment neovascularization.

Adult↗
PubMed1985

Reflux esophagitis: an update.

In recent years, much has been learned about the pathogenesis, diagnosis, and treatment of gastroesophageal (GE) reflux disease. Mucosal resistance, gastric contents, esophageal acid clearance, gastric emptying, and incompetency of the lower esophageal sphincter are contributing factors to GE reflux. Use of the various diagnostic tests and an overview of current therapy are summarized.

Alginates↗
PubMed1985

Competition between antigen and anti-idiotypes for rheumatoid factors.

Many idiotypic determinants on antibody molecules are thought to be located at the antigen binding site, and therefore the interaction between idiotype (Id) and anti-idiotype (anti-Id) is expected to be inhibited by the antigen. We describe two IgG and one IgM rheumatoid factors whose interactions with their respective anti-Id could only be partially inhibited by very large amounts of antigen, i.e., normal IgG. The anti-Id, however, readily inhibited the binding of their respective rheumatoid factors to IgG. The differences in interaction energies resulted in failure of antigen to readily block the Id-anti-Id interaction, and did not mean that the Id was not at the antigen combining site. The association constants for the Id-anti-Id interactions varied from 1.3 to 14.8 X 10(7) M-1, whereas the strength of the rheumatoid factor antigen bond is on the order of 10(5) M-1 for interaction with monomeric IgG. In addition, the anti-Id were able to remove rheumatoid factors that were bound to solid phase IgG, indicating that anti-Id have the potential for disrupting the immune complexes formed by antigen and antibody.

Animals↗
PubMed1984

Esophageal contraction pressures are not affected by normal menstrual cycles.

Previous studies of lower esophageal sphincter pressures during the menstrual cycle and pregnancy have suggested that the smooth muscle relaxing effect of progesterone depresses sphincter tone. Results, however, have been contradictory and limited to a small number of patients. We studied lower esophageal sphincter and distal peristaltic pressures during the follicular (days 2-8) and luteal (days 20-28) phases of the menstrual cycle. Twenty normal menstruating women (mean age 31 yr) not using oral contraceptives were evaluated. A low compliance pneumohydraulic infusion system was used for all studies. Lower esophageal sphincter pressure was determined by both rapid and station pull-through techniques. Distal peristaltic pressures were recorded 2 and 7 cm above the sphincter in response to 10 wet swallows (5 cc of H2O). Mean amplitude and duration in the distal esophagus were evaluated. Plasma progesterone and estrogen concentrations were obtained and correlated with changes in esophageal pressures. The results were as follows: (a) unlike prior investigations, we found the menstrual cycle had no effect on lower esophageal sphincter pressure and (b) likewise, no change in esophageal contractions in the distal esophagus was found during the cycle. We concluded that changes in female sex hormone concentrations that characterize the menstrual cycle are not associated with changes in parameters of esophageal motor function.

Adult↗
PubMed1981

Morphine antagonists and consummatory behaviors.

Opiate antagonists were tested for their effects upon either drinking or eating in eight experiments. Naloxone, nalorphine, and the active isomer of WIN 44,441 all reduce drinking. Neither an analog of nalorphine that does not cross the blood-brain barrier, nor the inactive isomer of WIN 44,441 is effective in reducing water intake. These data provide support for the conclusion that these antagonists ahve stereospecific effects within the central nervous system. Naloxone suppresses drinking following procedures inducing osmotic, volemic, or hormonal thirst. Naloxone suppresses eating following procedures inducing glucoprivation but does not alter eating elicited by tail-pressure. Collectively, these data lead to the conclusion that endorphins play a role in the organization of ingestive behavior following challenges to homeostasis.

Angiotensin II↗
PubMed1974

A technique for estimating the position of the oxygen-hemoglobin dissociation curve.

A nomogram was constructed which allows estimation of the P(50) value from the Po(2) and per cent O(2) saturation of a single venous blood sample. There was excellent correlation between 50 estimated P(50) values obtained in 27 severely ill patients when compared with P(50) values determined from constructed OH-DC's (correlation coefficient 0.92). The mean of the differences between the estimated and determined P(50) values was 1.5 mm Hg with a standard deviation of +/-1.1, and the maximum difference was 4 mm Hg.

Adolescent↗