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Biomedical subjects

J W Anderson

Publications and source records attributed to J W Anderson.

At least 19 recordsLinked to original sources
PubMed1992

Menthol in the upper airway depresses ventilation in newborn dogs.

Upper airway cooling depresses ventilation in the newborn dog. Since airway cooling stimulates laryngeal cold receptors and inhibits laryngeal mechanoreceptors, the type of afferent ending responsible for this reflex cannot be easily identified. l-menthol, a specific stimulant of cold receptors in the absence of any cooling, has been used to ascertain the discrete role of upper airway cold receptors in this ventilatory depression. Experiments were carried out in 8 anesthetized 7-14-day-old dogs breathing through a tracheostomy with the upper airway functionally isolated. Constant flows of warm air (37 degrees C), with and without addition of l-menthol, and cold air (25 degrees C) were delivered through the upper airway in the expiratory direction. As compared to warm air trials, cold air and warm air + l-menthol trials greatly reduced ventilation (57.5 +/- 10.7% and 52.8 +/- 11.7% of control, respectively; P less than 0.01) mostly due to a prolongation of Te (291.2 +/- 106.4% and 339.2 +/- 90.0%, respectively, P less than 0.01). Section of the superior laryngeal nerve abolished the response to cold air. However, a residual depressive effect of l-menthol was still present in 3 of 5 animals and was abolished by nasal anesthesia, suggesting the involvement of nasal cold receptors. The results suggest that in the newborn dog stimulation of laryngeal cold receptors, without any concurrent inhibition of laryngeal mechanoreceptors, is a sufficient stimulus to cause respiratory depression.

Animals↗
PubMed1992

Does the N100 evoked potential really habituate? Evidence from a paradigm appropriate to a clinical setting.

This study examined the N100 component of the event related potential in a habituation paradigm with short interstimulus intervals. The paradigm was designed to be relatively brief in duration (approx. 4 min for each of two conditions), so that it could be used for clinical populations with cognitive dysfunction, in which compliance may be a problem with long paradigms. Two conditions - Ignore and Attend - were employed with normal subjects. In each condition, 15 stimulus trains, each consisting of 10 innocuous tones, were presented. The eighth tone was a change stimulus. There was a fixed interstimulus interval of 1.1 s and an inter-train interval of 5 s. From the perspective of traditional Orienting Response theory, evidence was sought for within-train habituation in terms of diminished N100 amplitude to repeated stimuli, response recovery to the change stimulus, and dishabituation of the response to the following standard stimuli. Habituation was suggested by significant decreases of approx. 50% with stimulus repetition, and response recovery to the change stimulus in both conditions. However, there was no evidence of dishabituation following the change stimulus. These results confirm that N100 fails to meet the formal requirements of response habituation, suggesting instead that it may index an earlier process than the Orienting Response.

Acoustic Stimulation↗
PubMed1992

Weight loss and 2-y follow-up for 80 morbidly obese patients treated with intensive very-low-calorie diet and an education program.

Eighty morbidly obese individuals consecutively enrolled in a comprehensive very-low-calorie diet (VLCD) program were evaluated. Patients' mean initial body mass index was 45.5 kg/m2 and they lost 35.3 kg in 26 wk. Serum total cholesterol, low-density-lipoprotein cholesterol, and triglycerides decreased by 15.0%, 17.0%, and 14%, respectively. Systolic and diastolic blood pressure decreased by 8.7% and 10.0%, respectively. The 46 individuals completing 2-y follow-up were maintaining 48.0 +/- 7.6% (means +/- SE) of their weight loss. Morbidly obese persons lost substantial amounts of weight using a comprehensive VLCD program, reduced risk factors associated with obesity, and had encouraging long-term results, with 48% of weight loss maintained at 2 y of follow-up.

Adult↗
PubMed1992

Comparative weight loss in obese patients restarting a supplemented very-low-calorie diet.

Successive weight losses were compared for 21 patients restarting a very-low-calorie diet (VLCD) after weight regain. Patients broke VLCD2 sooner (3.8 vs 9.8 wk) and lost less (9.4 vs 19.1 kg), but weight-loss rates did not differ significantly (0.83 vs 0.71 kg/wk). Net loss post-VLCD2 was 12.0 kg. Restart patients had difficulty adhering to the repeat VLCD, which resulted in lower losses. However, similar weight-loss rates and significant net weight loss suggest repeat VLCDs can be effective.

Behavior Therapy↗
PubMed1992

Cholesterol-lowering effects of psyllium-enriched cereal as an adjunct to a prudent diet in the treatment of mild to moderate hypercholesterolemia.

Psyllium hydrophilic mucilloid, rich in soluble fiber, significantly lowers serum cholesterol concentrations. To investigate the lipid-lowering effects of a ready-to-eat cereal enriched with psyllium, we studied 44 hypercholesterolemic ambulatory individuals for 7 wk, using a randomized, double-blind, parallel design. After a 1-wk baseline period, subjects were randomly assigned to consume 114 g/d of a psyllium-flake or wheat-bran-flake cerearl for 6 wk adjunctive to an American Heart Association Step I diet. Serum high-density-lipoprotein cholesterol and triglycerides remained unchanged throughout the study; however, serum cholesterol and low-density lipoprotein (LDL) concentrations were significantly lower on psyllium than on wheat-bran cereal. Additionally, serum total and LDL cholesterol values were significantly lower than baseline values in the psyllium group. The dietary nutrient intake of the two groups did not differ except for soluble fiber. Adding psyllium-enriched cereal to a prudent low-fat diet may enhance dietary management of hypercholesterolemia.

Anticholesteremic Agents↗
PubMed1992

Oat bran increases serum acetate of hypercholesterolemic men.

Mechanisms for the hypocholesterolemic effects of oat bran remain unclear. Soluble fibers such as oat bran are fermented in the colon to short-chain fatty acids (SCFAs), which may enter the portal vein and attenuate hepatic cholesterol synthesis. To compare effects of oat bran and wheat bran on serum SCFA concentrations, 20 hypercholesterolemic men entered a metabolic ward and received control diets for 1 wk followed by oat-bran or wheat-bran diets for 3 wk. Oat bran decreased serum cholesterol 12.8% (P less than 0.001) whereas wheat bran had no effect. Peripheral serum SCFA concentrations were measured seven times over 14 h at the end of each diet. Serum acetate values from 1200 to 2200 were significantly higher in subjects fed oat-bran vs wheat-bran diets. Peak and incremental peak acetate values were also significantly higher than control values in subjects fed oat bran but not in subjects fed wheat bran. SCFA responses may contribute to the hypocholesterolemic effects of oat bran.

Acetates↗
PubMed1992

Prospective, randomized, controlled comparison of the effects of low-fat and low-fat plus high-fiber diets on serum lipid concentrations.

Previous studies examining the hypocholesterolemic effects of high-soluble-fiber diets have not been designed to control for dietary fat intake. Serum cholesterol reductions may therefore be accounted for by differences in consumption of fat. Moderately hypercholesterolemic, nonobese, Caucasian men and women, 30-50 y old were randomly assigned to low-fat, low-fat plus high-fiber, or usual-diet groups and followed for 12 mo. At 12 mo the high-fiber group consumed significantly more soluble fiber than both the low-fat and usual-diet groups (P = 0.0063 and P = 0.0001); the high-fiber group did not differ from the low-fat group in quantity of dietary fat consumed. The high-fiber group experienced a greater average reduction (13%) in serum cholesterol than did the low-fat (9%) and usual-diet (7%) groups. After adjustment for relevant covariates, the reduction in the high-fiber group was significantly greater than that in the low-fat group (P = 0.0482). Supplementation with soluble fiber reduces serum cholesterol beyond the reduction observed with low-fat diet alone.

Adolescent↗
PubMed1992

Comparative study of antipneumocystis agents in rats by using a Pneumocystis carinii-specific DNA probe to quantitate infection.

A repetitive genomic DNA clone (B12-2) that specifically hybridizes to Pneumocystis carinii DNA has been identified. No cross-hybridization to genomic DNA prepared from bacteria, other fungi, protozoa, or mammals was observed. Clone B12-2 is multiply represented in the P. carinii genome. By direct hybridization to DNA prepared from the lungs of immunosuppressed rats, the probe can detect the equivalent of fewer than 1,000 P. carinii organisms. A hybridization assay employing clone B12-2 has been developed to quantitate organism load in the rat model for P. carinii. Application of the assay to track the accumulation of organisms during the immunosuppression regimen as well as to monitor the efficacy of two drug therapies used clinically for the treatment of P. carinii pneumonia is described here. The clone B12-2 hybridization assay for the determination of P. carinii organism load possesses several advantageous features and thus should serve to complement conventional staining and immunohistochemical methods.

Animals↗
PubMed1992

Fiber and weight management.

Fiber is the portion of plant cells not digested in the human small intestine. Benefits of fiber consumption have been documented in treatment of obesity and obesity-related risk factors. In the last century carbohydrate intake and, thus, fiber intake have declined in the U.S. diet at the same time obesity has increased. Higher fiber intake can be achieved by adding high fiber foods or supplements to the diet. A combination of water soluble and water insoluble fiber sources offer the greatest health and weight control benefits. A high fiber weight-reducing diet is most beneficial as part of a lifestyle modification program for weight management.

Body Weight↗
PubMed1992

Benefits and risks of an intensive very-low-calorie diet program for severe obesity.

Comprehensive very-low-calorie diet (VLCD) programs are the preferred treatment for selected obese individuals. They combine energy intakes of 400-800 kcal/day with medical monitoring and intensive lifestyle education. Typical VLCD patients have median body mass indexes of 36 kg/m2 and have median ages of 40 years. About 70% are female. Commonly associated medical problems include hypertension in 50%, hyperlipidemia in 41%, and diabetes mellitus or glucose intolerance in 14%. Typical weight loss with VLCD is around 21 kg in 16 wk. Reductions of 8-13% in blood pressure, 5-15% in serum total cholesterol, 5-20% in low-density lipoprotein-cholesterol, 15-50% in triglycerides, and decreases in blood glucose and glycohemoglobin in diabetic individuals accompany weight loss. VLCD-associated side effects can be managed medically without discontinuing treatment. Lifestyle education promotes long-term weight maintenance of approximately 56% 2 yr after VLCD treatment. Weight losses using comprehensive VLCDs allow moderately to morbidly obese persons to achieve greater benefits than other nonsurgical treatments and should be considered before opting for surgical treatment.

Diet, Reducing↗
PubMed1991

Involvement of the carboxy-terminal residue in the active site of the histidine-containing protein, HPr, of the phosphoenolpyruvate:sugar phosphotransferase system of Escherichia coli.

Histidine-containing protein, HPr, of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system has an active site that involves His-15, which is phosphorylated to form a N delta 1-P-histidine, Arg-17, and the carboxy-terminal residue Glu-85. Mutant HPrs with alterations to the three C-terminal residues, Glu-85, Leu-84, and Glu-83, were produced by site-directed mutagenesis. The properties of these mutants were assessed by kinetic analysis of enzyme I, enzyme IImannose, enzyme IIN-acetylglucosamine, and enzyme IImannitol, and the phosphohydrolysis properties of the HPr mutants. The results show that it is the C-terminal alpha-carboxyl of Glu-85 that is involved in the active site, and this involvement may be restricted to the phosphoryl donor action of HPr. The contribution of this alpha-carboxyl group is modest as the deletion of Glu-85 resulted in the reduction of the enzyme II activity (kcat/Km) to about 33%. Removal of both Glu-85 and Leu-84 yields an HPr that is an impaired substrate of both the enzyme I and enzyme II reactions. Glu-83 appears to have no role in the active site.

Bacterial Proteins↗
PubMed1991

Expression of biologically active heterodimeric bovine follicle-stimulating hormone in milk of transgenic mice.

Follicle-stimulating hormone (FSH; follitropin) is a pituitary glycoprotein composed of two post-translationally modified subunits, which must properly assemble to be biologically active. FSH has been difficult to purify and to obtain in quantities sufficient for detailed biochemical studies. We have targeted FSH expression to the mammary gland of transgenic mice by using cDNAs encoding the bovine alpha and FSH beta subunits and a modified rat beta-casein gene-based expression system. Lines of bigenic mice expressing both subunits have been generated either by coinjection of the subunit transgenes or by mating mice that acquired and expressed transgenes encoding an individual subunit. Up to 60 international units (15 micrograms) of biologically active FSH per ml was detected in the milk of the bigenic mice. These lines provide a model system for studying the post-transcriptional mechanisms that effect the expression and secretion of this heterodimeric hormone.

Animals↗
PubMed1991

Laryngeal afferent activity and reflexes in the guinea pig.

We have investigated the various sensory modalities represented in the laryngeal nerves of the guinea pig. In addition, we have examined the defensive responses to mechanical stimuli and capsaicin instillation into the laryngeal lumen of the same species. Recording from both the whole superior laryngeal nerve and from single units of the same nerve revealed the presence of afferent activity related (1) to the contraction of laryngeal muscles and/or the 'tracheal tug', (2) to transmural pressure changes, either positive or negative and (3) to mechanical and chemical irritants. The irritant type receptors of this species, when challenged with water solutions, show two distinct patterns of activation: some behave as osmoreceptors, some respond to the lack of chloride ions. Challenges with capsaicin solutions activated one ending with the characteristics of a C-fiber receptor that failed to respond to a subsequent trial. This behavior is consistent with the reflex apnea, dependent on an intact laryngeal innervation, induced by capsaicin instillation that was not elicitable on repeating the challenge. Cough to mechanical probing of the supraglottic area depended on an intact SLN, whereas cough elicited from the subglottic area depended on an intact RLN. Cough to mechanical stimulation could not be desensitized by capsaicin. These findings suggest the presence of two independent afferent pathways for defensive responses.

Afferent Pathways↗
PubMed1991

Response of laryngeal receptors to water solutions of different osmolality and ionic composition.

Water-responsive laryngeal receptors with fibres in the superior laryngeal nerve were studied to characterize the specific physicochemical properties of aqueous solutions that activate these endings. The responses to water (37 degrees C) of 141 receptors were studied in 39 anaesthetized dogs breathing through a tracheostomy with the larynx functionally isolated. Of the 89 receptors stimulated by water, 53 were also challenged with isosmotic (275-315 mOsm) solutions of dextrose and sodium gluconate at 37 degrees C. Receptors that only responded to water (n = 31) with a long delay, long duration discharge were generally respiratory modulated. On the other hand, laryngeal receptors that responded to all test solutions (n = 22) with a short delay, short duration discharge were generally not respiratory modulated. We conclude that the former type of receptor responds to lower osmolality, whereas the latter responds to the lack of chloride ions in the test solutions. These two types of receptor may be responsible for the cough and bronchoconstriction induced by inhaled aerosols of different osmolalities and ionic compositions.

Action Potentials↗
PubMed1991

Lipid responses of hypercholesterolemic men to oat-bran and wheat-bran intake.

The hypocholesterolemic effects of oat bran (OB) have been recently challenged. To carefully document the hypocholesterolemic effects of OB, 20 hypercholesterolemic men admitted to a metabolic ward were randomly allocated to either OB or wheat bran (WB) for 21 d after a 7-d control-diet period. Control and treatment diets were designed to be identical in energy content and nutrients, differing only in the amount of soluble fiber. After 21 d, OB significantly decreased total cholesterol by 12.8% (P less than 0.001), low-density-lipoprotein cholesterol by 12.1% (P less than 0.004), and apolipoprotein B-100 by 13.7% (P less than 0.001) whereas WB had no significant effect. High-density-lipoprotein cholesterol and apolipoprotein A-I did not change significantly in either group. Serum triglycerides decreased by 10% in both groups but the decrease was only significant (P less than 0.04) in WB subjects. OB but not WB significantly reduced total cholesterol and other atherogenic lipoprotein fractions independent of other dietary changes.

Adult↗
PubMed1991

Bakery products lower serum cholesterol concentrations in hypercholesterolemic men.

Several foods rich in water-soluble fiber have documented hypocholesterolemic effects. To determine the cholesterol-lowering effects of high-soluble-fiber intake from refined, wheat-based bakery products, 10 hypercholesterolemic subjects ate a high-carbohydrate, high-fiber control diet in a metabolic ward for 7 d, followed by a diet rich in soluble fiber from bakery products for 21 d. Both control and bakery diets provided 25 g total dietary fiber/d; however, the bakery diet provided 6 g soluble fiber/d more than the control diet. Average serum total cholesterol concentrations stabilized during the control diet and then decreased 6.4% during the bakery diet. Serum low-density-lipoprotein cholesterol decreased 8.5% (P less than 0.05), apolipoprotein B-100 decreased 8.7% (P less than 0.05), and the ratio of apolipoprotein B-100 to apolipoprotein A-I decreased 9.5% (P less than 0.05) during the bakery diet. Results confirm previous reports that a small increase in soluble-fiber intake of approximately 6 g/d modestly decreases atherogenic serum cholesterol concentrations, regardless of fiber source.

Adult↗
PubMed1991

Metabolic effects of high-carbohydrate, high-fiber diets for insulin-dependent diabetic individuals.

The metabolic effects of high-carbohydrate (70%), high-fiber (70 g) (HCHF) and low-carbohydrate (39%), low-fiber (10 g) (LCLF) diets were examined for 10 subjects with insulin-dependent diabetes mellitus (IDDM). After a 1-wk control period subjects on a metabolic ward were randomly allocated to HCHF or LCLF diets for 4 wk. After a 6-wk washout period subjects re-entered the metabolic ward for 4 wk on the alternate diet. Artificial-pancreas studies were performed on each diet for measurement of insulin requirements. Compared with the LCLF diet, the HCHF diet reduced basal insulin requirements (P less than 0.025), increased carbohydrate disposed of per unit insulin (P less than 0.0008), and lowered total (P less than 0.0004) and high-density-lipoprotein cholesterol (P less than 0.0013). Glycemic control and other lipid fractions did not differ significantly. These results suggest that in IDDM patients, HCHF diets enhance peripheral glucose disposal, decrease basal insulin requirements, and lower total cholesterol without altering glycemic control or triglycerides.

Adult↗