Biomedical subjects

D J Smith

Publications and source records attributed to D J Smith.

At least 307 records · Page 17Linked to original sources

PubMed1990

The moral reasoning of juvenile delinquents: a meta-analysis.

To test the hypothesized immaturity of juvenile delinquents' moral reasoning, the results of 15 studies of the moral reasoning of juvenile delinquents were integrated quantitatively using meta-analysis. Hedges and Olkin (1985) methods were used to (a) compute effect sizes, (b) test the homogeneity of the obtained effect sizes, and (c) test the statistical significance of the pooled mean effect size. The results supported the hypothesis that the moral reasoning of juvenile delinquents is immature. It was concluded that several other issues are in need of investigation.

Adolescent↗

PubMed1990

Effect of local deposition of antigen on salivary immune responses and reaccumulation of mutans streptococci.

In this study glucosyltransferase (GTF) from Streptococcus sobrinus was topically administered onto the lower lips of young adults. The effect of this route of antigenic exposure on labial and parotid gland and serum antibody levels to GTF and on the reaccumulation of indigenous mutans streptococci after a dental prophylaxis was then measured. Young adults between 18 and 42 years of age were screened for levels of antibody activity to GTF in parotid and labial gland salivas and levels of mutans streptococci in their whole saliva. Prior to antigen administration, two groups were formed which had similar distributions of mutans streptococci in their whole saliva. Antigen (GTF) or placebo, each combined with aluminum phosphate (AP), was then administered to the lower lip daily for 5 days. Immediately prior to topical application of GTF or placebo to the labial salivary glands, all subjects were given a dental prophylaxis. Statistically significant differences in anti-GTF IgA antibody activity in parotid or labial salivas were not observed between the GTF-administered and the placebo groups during the 6 weeks following topical application. However, the proportions of indigenous mutans streptococci/total streptococcal flora, or total cultivable flora, were always lower in the whole salivas of the GTF, compared with the placebo group. These differences were statistically significant on days 13, 20, 34, and 41 after initial topical application. Delays in reaccumulation were significantly associated (P less than 0.025) with elevations in parotid saliva IgA antibody levels of all subjects. Seven of 10 of the subjects demonstrating this association were in the group to which GTF was topically administered.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗

PubMed1990

Ethanol consumption decreases alanine uptake by rat basolateral liver plasma membrane vesicles.

Alterations of amino acid metabolism may play an important role in the pathogenesis of ethanol-induced liver disease. Previous studies indicate that ethanol added in vitro inhibits amino acid uptake by cultured hepatocytes and liver plasma membrane vesicles; however, the effect of chronic ethanol consumption on amino acid uptake by the liver remains unknown. Therefore, the present studies were performed to determine if chronic ethanol consumption impairs alanine uptake by rat basolateral liver plasma membrane vesicles. Male Sprague-Dawley rats were pair-fed for 6 weeks a diet containing 36% of calories as ethanol or a control diet in which ethanol was isocalorically replaced with carbohydrate. Chronic ethanol consumption reduced basolateral liver plasma membrane sodium-dependent alanine transport activity by 36.3% +/- 15.9% (p less than 0.01). This reduction was caused primarily by impaired activity of amino acid transport system A. The response of system A to glucagon was reduced in the ethanol-fed rats, suggesting that impaired hormonal regulation is at least partially responsible for the lower system-A activity. Kinetic analysis shows that ethanol consumption reduces the Vmax of sodium-dependent alanine transport without affecting the Km. These studies indicate that chronic ethanol consumption reduces alanine uptake by the rat liver. They further show that the reduced uptake is at least partially caused by an intrinsic defect in membrane-transport processes rather than another regulatory mechanism.

Alanine↗

PubMed1990

Immunogenic potential of carpal implants.

This study investigated whether a cellular or a humoral-mediated immunologic response to silicone carpal prostheses could be detected in animals previously sensitized to silicone. Silicone carpal prostheses were emulsified in Freund's complete adjuvant (FCA). This emulsion was injected into guinea pigs weekly for 6 weeks. Controls received only FCA. Four weeks later a carpal prosthesis was implanted. Histology showed the implanted prosthesis encapsulated by fibrous tissue in sensitized animals, with a mononuclear infiltrate within the fibrous periprosthetic capsule consistent with a cellular immune response. Skin testing of the sensitized animals showed a true correlate response to the silicone antigen challenge, whereas no response was observed in the control group. The passive cutaneous anaphylaxis reaction in sensitized animals was positive, emphasizing that the antigen-antibody response was passively transferred. Tissue adjacent to the silicone implant in sensitized animals revealed an IgG deposition around the silicone particles by the fluorescent antibody technique. Control animals showed none of these reactions. These results indicate that microparticulate matter from carpal implants can possibly initiate both a cellular immunologic response and the production of a circulating antibody.

Animals↗

PubMed1990

Superoxide dismutase prevents lipid peroxidation in burned patients.

Animal models and human studies have shown that conjugated dienes rise in the plasma after thermal injury. These dienes may serve as a marker of oxygen radical-mediated tissue injury. Twelve burn patients were randomized to receive the antioxidant enzyme polyethylene glycol-conjugated superoxide dismutase (PEG-SOD). Patients received either 500 or 1000 units per kilogram of PEG-SOD intravenously within 6 h of injury. Plasma samples were collected and conjugated diene levels were compared to diene levels of burn patients not treated and to diene levels from normal volunteers. Conjugated diene levels were increased in burn patients. PEG-SOD in either dose initially decreased conjugated diene levels in the plasma of both treatment groups. By 72 h, the diene levels increased in the 500 unit/kg group, but remained at near control levels in the 1000 unit/kg group for up to 200 h after injury. These data suggest that PEG-SOD is capable of preventing conjugated dienes formed as the result of oxygen radical production. It appears that 1000 units/kg is more effective than 500 units/kg in preventing conjugated diene formation.

Adult↗

PubMed1990

Topical antimicrobial testing of burn wound microorganisms: evaluation of a new technique.

A new system of determining susceptibility of burn wound microorganisms to topical antimicrobial therapy was studied. The new method, TOPITEST, employs a methacrylate vehicle impregnated with various antimicrobial agents and an agar overlay. Test plates can be inoculated by a direct swab culture of the wound or with micro-organisms isolated by other methods. This new technique was compared to an agar well diffusion (AWD) method using commercially compounded antimicrobials and biopsy-recovered organisms. The new test method provided comparable results to the more established AWD test when using biopsy-recovered organisms. Using the swab culture technique, however, TOPITEST had a high rate of failure to recover sufficient organisms from the burn wound for testing. The new, more standardized test provided results earlier than the AWD test, but may prove to be less cost effective.

Administration, Topical↗

PubMed1990

Interrelationship of atrial natriuretic peptide, atrial volume, and renal function in premature infants.

Infants experience dramatic changes in fluid balance during the first few days of life, which provides an opportunity to observe the interrelationships of changing atrial size, atrial natriuretic peptide (ANP) secretion, and renal function during a relatively short period. To study these relationships, we examined nine infant boys (mean birth weight 1180 gm and gestational age 30 weeks) at 20 to 28 hours of age and then at four 24-hour intervals. Measurements included plasma ANP concentration, two-dimensional echocardiographic estimations of left and right atrial volumes, Doppler determination of ductus arteriosus patency, creatinine clearance, urine flow rate, urinary sodium excretion, and cyclic guanosine monophosphate (cGMP) excretion. Plasma ANP concentration was found to decrease with age and to correlate with decreasing size of the right atrium, closure of the ductus arteriosus, urinary cGMP excretion, and sodium excretion. We speculate that elevated plasma ANP values in a preterm neonate reflect an expanded volume state. As volume contraction, reflected by decreasing atrial volume and body weight occurs, ANP levels decrease, which may diminish diuresis. These findings are compatible with a significant role for ANP in volume homeostasis of newborn infants.

Atrial Natriuretic Factor↗

PubMed1990

Cloning and heterologous expression of the penicillin biosynthetic gene cluster from penicillum chrysogenum.

A cosmid clone containing the putative penicillin biosynthetic gene cluster from Penicillium chrysogenum was used to transform the related filamentous fungi Neurospora crassa and Aspergillus niger, which do not produce beta-lactam antibiotics. Both of the transformed hosts contained intact P. chrysogenum DNA derived from the cosmid clone and produced authentic penicillin V. Assays of penicillin biosynthetic enzyme activity additionally demonstrated that they possessed delta-(L-alpha-amino-adipyl)-L-cysteinyl-D-valine synthetase (ACVS), isopenicillin N synthetase (IPNS) and acyl coenzyme A:6-aminopenicillanic acid acyltransferase (ACT) activity. The data suggests that genes encoding all the enzymes necessary for the biosynthesis of penicillin from amino acid precursors are closely linked in P. chrysogenum and constitute a gene cluster.

Acyltransferases↗

PubMed1990

Actinobacillus actinomycetemcomitans mitogenicity for B cells can be attributed to lipopolysaccharide.

The purpose of this investigation was to determine the component(s) of whole Actinobacillus actinomycetemcomitans bacteria responsible for B cell mitogenic activity. Congenitally athymic "nude" rats were used as a source of B cells devoid of T lymphocyte activity. Spleen cells were cultured with, or without, whole formalin-killed A. actinomycetemcomitans bacteria or with purified LPS from A. actinomycetemcomitans. Dose-response curves to A. actinomycetemcomitans cells or to A. actinomycetemcomitans-LPS showed that responses were dose dependent. If optimal quantities of both A. actinomycetemcomitans and A. actinomycetemcomitans-LPS were added in combination, the proliferative responses were the same as if either was added alone, i.e., the responses were not additive. Polymyxin B at 2 micrograms/well completely abrogated the proliferative response of athymic rat splenocytes to 10(7) A. actinomycetemcomitans cells or to 1.25 micrograms A. actinomycetemcomitans-LPS/well. Therefore, the in vitro early proliferative response of B cells to A. actinomycetemcomitans can be attributed to the presence of LPS on A. actinomycetemcomitans cells. A considerable portion of the in situ lymphocytic gingival response to A. actinomycetemcomitans infection seen in periodontal disease patients may be a B cell mitogenic response to the LPS of this bacterium.

Actinobacillus↗

PubMed1990

Salivary IgA antibody to oral streptococcal antigens in predentate infants.

Salivary IgA antibodies to oral streptococci which colonize the infant oral cavity soon after birth were analyzed in 53 whole salivas of 17 infants who were between three and 27 weeks old. Antibody activities to Streptococcus mitis cells were detected by enzyme linked immunosorbent assay in 78% of the whole salivas by the twelfth week of age. This antibody activity was associated with polymeric IgA as determined after gel filtration of salivas on Superose 6, followed by ELISA. Western blot analyses were used to detect IgA antibodies to Streptococcus mitis and Streptococcus salivarius culture supernatants. Forty one, and 91% of saliva samples contained IgA antibody which reacted in Western blot analyses with S. salivarius and S. mitis culture supernatants, respectively. The youngest infant to show reactive IgA antibody with either oral streptococcal antigen preparation was five week old. Salivary IgA antibody to either bacterial culture supernatant was detected in Western blot only after the isolation of the respective streptococcal species from the oral cavity of these young infants. Some heterogeneity was observed among patterns developed with salivas from different infants. These results suggest that salivary IgA antibody responses may be induced by oral colonization (S. mitis, S. salivarius) by the end of the first month of life.

Age Factors↗

PubMed1990

Dental caries in congenitally athymic rats.

The importance of the immune response in dental infection was evaluated in heterozygous (rnu/+) normal and homozygous (rnu/rnu) congenitally athymic "nude" Rowett rats. Animals of both types were infected, or immunized and infected, with mutans streptococci (Streptococcus sobrinus strain 6715). The mean numbers of S. sobrinus cells recovered from the nude rats were higher than those from comparable (immune/nonimmune) normal rats in 10 of 12 possible comparisons. Also, S. sobrinus constituted a greater percentage of the total streptococci in the nude rats compared with normal animals (6 of 6 possible comparisons). Antibody to S. sobrinus whole cells or to S. sobrinus glucosyltransferase from nude rats in serum or in saliva was significantly lower (or absent) than that of comparable normal rats. This was seen after infection, but was most pronounced after immunization (and infection). Dental caries was also significantly elevated in the congenitally athymic animals. Immunologic deficiency of congenitally athymic rats can lead to a greater infection level with mutans streptococci and increased dental caries.

Analysis of Variance↗

PubMed1990

Faculty willingness to accommodate students with learning disabilities: a comparison among academic divisions.

One hundred seven faculty members at a northwestern college responded to a questionnaire devised to assess faculty willingness to provide students with learning disabilities instructional, assignment, examination, and special assistance accommodations. Faculty responses to the questionnaire were analyzed to determine if differences existed among faculty in the colleges of Education, Business, and Arts and Sciences. Results indicate that, in general, faculty were willing to provide students with learning disabilities accommodations, but that differences exist among the three academic divisions as to faculty willingness to provide students accommodations. The implications of these results for colleges and universities and future research are discussed.

Achievement↗

PubMed1990

Characterization of rat T-cell clones with bacterial specificity.

We have isolated 10 rat T-cell clones from the spleen or lymph nodes of seven different donors. These rats were immunized with 2-5 x 10(8) killed Actinobacillus actinomycetemcomitans (Aa) bacteria, injected either subcutaneously (s.c.) in complete Freund's adjuvant or intraperitoneally (i.p.) in saline. Clones studied to date have demonstrated a T-helper (Th) phenotype W3/13+, W3/25+, OX8- and OX22-. Clones were not stimulated in vitro by purified Aa-lipopolysaccharide (LPS) or heterologous Gram-negative bacteria, but proliferated when stimulated by bacteria representative of each of the three serological groups of Actinobacillus, indicating specificity for an Actinobacillus-common antigen other than LPS. One clone (A4) proliferated vigorously when stimulated with concanavalin A (Con A) in vitro, produced interleukin-2 (IL-2) and was provisionally classified as a Th1 type. This appears to be one of the few Th1-type rat clones reported. All other clones tested did not produce IL-2, exhibited B-cell help to some extent, did not induce delayed-type hypersensitivity (DTH) when injected into the footpads of naive rats along with the specific antigen, and were classified as Th2 type. Adoptive transfer of 10(6) cells of one Th2-type Aa-specific clone into syngeneic recipients resulted in a specific splenocyte in vitro response to Aa 12-14 weeks after cell transfer, indicating survival of cloned cells in recipient animals. The use of such clones in studies of experimental periodontal disease is discussed.

Actinobacillus↗

PubMed1990

[The relationship between nursing practice, nursing, and nursing philosophy].

The activities of the three dimensions of nursing does not occur in isolation. Nursing practice, the field of study of nursing science, has characteristics which influence the scientific practice of nursing. Nursing practice is constituted by the nurse practitioner as a result of the fact that the pre-scientific interpretations of the nurse give form (gestalte) to nursing interactions. From a functional perception in nursing science, the scientific practitioner must take cognisance of the pre-scientific interpretations. Besides the empirical reality, specific values and assumptions form an integral part of this practice of science in Nursing. The third dimension, the philosophy of nursing brings greater clarity in that the activities of the first two dimensions can be organised, analysed and evaluated.

Humans↗

PubMed1990

Ischemia-reperfusion in humans. Appearance of xanthine oxidase activity.

We evaluated effluent blood from extremities of human patients undergoing reconstructive surgical treatment, which is routinely accompanied by upper-extremity exsanguination and application of a tourniquet, resulting in total interruption of arterial blood flow to one upper extremity. After tourniquet release (reperfusion), there were immediate increases in the plasma levels of xanthine oxidase activity, uric acid, and histamine in the ipsilateral limb and much smaller increases, if any, in levels of the same materials in plasma obtained from the contralateral extremity. There was no detectable xanthine dehydrogenase activity in plasma from either limb. Plasma also contained evidence of products consistent with the formation of oxygen-derived free radicals, namely, the appearance predominantly in the reperfused limb of hemoglobin and fluorescent compounds. These data indicate for the first time in humans that ischemia-reperfusion events are associated with the appearance of xanthine oxidase activity and its products in the plasma effluent.

Adult↗

PubMed1990

Prolonged whole body immersion in cold water: hormonal and metabolic changes.

To characterize metabolic and hormonal responses during prolonged whole body immersion, 16 divers wearing dry suits completed four immersions in 5 degrees C water during each of two 5-day air saturation dives at 6.1 meters of sea water. One immersion began in the AM (1000 h) and one began in the PM (2200 h) to evaluate diurnal variations. Venous blood samples were obtained before and after completion of each immersion. Cortisol and ACTH levels demonstrated diurnal variation, with larger increases occurring after PM immersions. A greater than three-fold postimmersion increase occurred in norepinephrine (NE). There were significant increases in triiodothyronine (T3) uptake and epinephrine, but no change in T3, thyroxine, thyrotrophic hormone, and dopamine. Postimmersion free fatty acid levels increased 409% from preimmersion levels; glucose levels declined, and lactate increased significantly. Only changes in NE correlated significantly with changes in rectal temperature. In summary, when subjects are immersed in cold water for prolonged periods, with a slow rate of body cooling afforded by thermal protection and intermittent exercise, hormonal and metabolic changes occur that are similar in direction and magnitude to short-duration unprotected exposures. Except for cortisol and ACTH, none of the other measured variables exhibited diurnal alterations.

Adult↗

PubMed1990

Lack of diurnal effects on periodic exercise during prolonged cold water immersion.

Diurnal effects on periodic exercise were examined in 8 male divers wearing passive thermal protection during whole body immersions in 5 degrees C water for periods of up to 6 h. Studies were done during the course of 5-day air saturation dives at a depth of 1.61 ATA, with immersions beginning at 1000 h (AM) and 2200 h (PM). During each hour of immersion, leg exercise was done for 3 min each at workloads of 50, 70, and 90 W. Heart rate (HR) at each workload increased uniformly with immersion time, without a change in slope of HR vs. workload. No AM or PM differences occurred. AM resting VO2 increased linearly, and to the same extent as PM, with exposure time. VO2 at 50 W also increased at the same rate as resting values. VO2 at 70 and 90 W were similar for AM and PM and did not vary significantly during the 6-h immersions. Temporal increases in exercise HR may reflect cardiac compensation of diminished plasma volume. Workloads greater than or equal to 70 W generate enough metabolic heat in this specific condition to meet the thermogenic requirement. Lack of diurnal effects on exercise variables may be due to environmental conditions suppressing circadian rhythms.

Adult↗

PubMed1990

Heart rate and blood lactate concentration during on-ice training in speed skating.

Heart rates and blood lactate concentrations were measured in four sprint and three all-round male members of the Canadian National Speed Skating Team. Responses to various training programs were obtained over a two-week period in November following four weeks of ice training, and in January during mid-season competition. Seven different training programs used by sprint and all-round speed skaters were monitored including a skating velocity and heart rate/lactate response. The protocol for this response was 5 x 4 min exercise intervals with 4 min recovery. A significant increase in blood lactate (3.9 +/- 0.4 to 5.2 +/- 0.5 mmol.L-1) was observed between intensity levels 2 and 3. During the specific 1500 m training program for sprinters, there was an increase in blood lactate and a decrease in heart rate for each exercise interval, despite a maintenance in lap speed throughout the whole program. The highest blood lactate concentrations seen in training and competition were 18.5 +/- 0.3 mmol.L-1 in specific 1500 m training and 17.7 +/- 1.8 mmol.L-1 following the 1000 m race.

Adult↗