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Biomedical subjects

J Richardson

Publications and source records attributed to J Richardson.

At least 217 records · Page 12Linked to original sources
PubMed1994

Parenting behaviors and the onset of smoking and alcohol use: a longitudinal study.

OBJECTIVE: To identify which specific parenting behaviors are associated with the onset of alcohol and tobacco use and how they are associated. DESIGN: Prospective cohort study of two groups of preadolescents surveyed annually, the first group for 4 years, the second for 3 years. SETTING: Two public school districts in Southern California. SUBJECTS: 1034 fifth graders and 1266 seventh graders began the study after obtaining parental consent to complete surveys in a classroom setting. By the last measurement, attrition was 37 and 38% for the two cohorts, respectively. MAIN OUTCOME MEASURES: The onset of tobacco or alcohol use in the last month. RESULTS: Children who reported that parents spent more time with them and communicated with them more frequently had lower onset rates of using alcohol and tobacco in the last month. These parental interactions lead to more positive relationships with their children. Parental monitoring and positive relations were protective factors for disruptive behavior and the selection of substance-using friends. Disruptive behavior increased the odds of adolescents drinking in the last month approximately twofold and of smoking in the last month two to fourfold. CONCLUSIONS: This study provides further evidence that parenting behaviors are significant precursors to adolescent disruptive behavior, vulnerability to peer pressure, and subsequent substance use. Parents should be targeted in future substance use prevention programs, before their children reach adolescence.

Adolescent↗
PubMed1994

Talking with children: some basic counselling skills.

The ability to listen to a child is the starting point of a therapeutic relationship. The nurse should respect the child as an individual. An understanding of child development, particularly of language and thought processes, helps adults to communicate more effectively with children. Play may be an appropriate way of communicating with younger children.

Adult↗
PubMed1993

Isolation and kinetic characterization of the calmodulin methyltransferase from sheep brain.

The methyltransferase that catalyzes the trimethylation of lysine 115 in calmodulin has been purified from sheep brain. The enzyme is a monomer with an apparent molecular weight of 38,000 on the basis of gel filtration chromatography and SDS-polyacrylamide electrophoresis. In the presence of calcium the methyltransferase exhibited a Km of 100 nM for unmethylated calmodulin and a kcat of 0.0278 s-1. The enzyme was able to use calcium-depleted calmodulin as a substrate, albeit with less efficiency. The methylation of calcium-depleted calmodulin was inhibited by increases in ionic strength, whereas methylation of calcium-saturated calmodulin was not affected. This suggests a difference in the mode of interaction of calcium-saturated and calcium-depleted calmodulins with the enzyme. As with calmodulin's interactions with other calmodulin-dependent enzymes, the oxidation of the methionines of calmodulin by performic acid treatment decreases the ability of the methyltransferase to recognize and methylate calmodulin. A calmodulin-binding peptide based on the calmodulin-dependent protein kinase II sequence and the naphthalenesulfonamide W-7 inhibit the calmodulin methyltransferase-calmodulin interaction in a calcium-dependent manner. Removal of the NH2-terminal lobe (residues 1-77) does not affect the ability of the calmodulin methyltransferase to recognize and methylate lysine 115. Thus, the determinants for calmodulin methyltransferase binding reside solely in the COOH-terminal lobe of calmodulin. Further, structural features within this region, in particular, the hydrophobic cleft, that are manifested upon calcium binding may contribute to the interaction of calmodulin with the enzyme.

Amino Acid Sequence↗
PubMed1993

A phase I study of an anti-CD22-deglycosylated ricin A chain immunotoxin in the treatment of B-cell lymphomas resistant to conventional therapy.

Twenty-six patients, whose B-cell lymphoma had relapsed after conventional therapies, were treated in a phase I dose escalation study with an immunotoxin consisting of a mouse CD22 monoclonal antibody (RFB4:IgG1K) coupled to chemically deglycosylated ricin A chain (dgA). Two to 12 doses of the immunotoxin were infused intravenously at 48-hour intervals. The peak serum concentration and half-life (T1/2) did not correlate directly with the dose and averaged 3.8 micrograms/mL and 7.8 hours, respectively. The main dose-limiting toxicity was caused by the vascular leak syndrome (VLS) consisting of weight gain, edema, serum albumin decrease, and critically by pulmonary edema. Myalgia occurred frequently and was only dose limiting in one patient who developed rhabdomyolysis. The presence of lymphoma cells in the blood (> or = 10(10)/L) and clinically detectable splenomegaly were associated with reduced toxicity and a shorter T1/2. Nine of 24 evaluable patients (37.5%) made antibody to either mouse Ig or dgA. There were five partial responses (PR) and one complete response (CR) lasting 30 to 78 days. High peak concentrations of immunotoxin in the serum, a long T1/2, and large areas under the curve (AUC) correlated with both clinical response and toxicity. None of three patients with CD5+ lymphomas (including two CLL patients) had more than mild toxicity or responded to the immunotoxin.

Adult↗
PubMed1993

Purification and characterization of a nitrous oxide reductase from Thiosphaera pantotropha. Implications for the mechanism of aerobic nitrous oxide reduction.

The aerobic denitrifer Thiosphaera pantotropha is able to reduce simultaneously nitrous oxide and oxygen even after anaerobic growth [Bell, L. C. & Ferguson, S. J. (1991) Biochem J. 273, 423-427]. A nitrous oxide reductase was purified from anaerobically grown T. pantotropha cells. It is argued, on the basis of inhibitor sensitivities and from immunological evidence, that the same nitrous oxide reductase is involved in nitrous oxide reduction in aerobically grown cells. The purified nitrous oxide reductase was shown to have molecular properties very similar to nitrous oxide reductases previously isolated from anaerobically denitrifying bacteria. The visible absorption spectra of the T. pantotropha enzyme resemble those of the oxygen-affected form of nitrous oxide reductases from other organisms. It is thus concluded that the T. pantotropha nitrous oxide reductase is not peculiarly resistant to the structural changes caused by oxygen. The activity of the purified T. pantotropha nitrous oxide reductase was reconstituted in vitro using horse heart cytochrome c, T. pantotropha cytochrome c551 and T. pantotropha pseudoazurin as electron donors. It is suggested on this basis that either of the T. pantotropha electron-carrier proteins are possible physiological electron donors to T. pantotropha nitrous oxide reductase. Oxygen was shown not to inhibit the in-vitro reduction of nitrous oxide with horse heart ferrocytochrome c as electron donor to the reductase.

Aerobiosis↗
PubMed1993

Continuous intercostal nerve block versus epidural morphine for postthoracotomy analgesia.

Twenty patients undergoing elective thoracotomy were randomized into two groups, receiving either lumbar epidural morphine (n = 10) or continuous extrapleural intercostal nerve block (n = 10). Subjective pain relief was assessed on a linear visual analogue scale. Pulmonary function (peak expiratory flow rate, forced expiratory volume in 1 second, and forced vital capacity) was measured on the day before operation and daily for 4 days after operation. Pulse oximetry monitoring was used to determine the incidence of hypoxemia. No significant difference was observed between the groups concerning pain relief (except at 28 hours, in favor of the intercostal nerve block group), respiratory performance, or arterial oxygen saturation. Vomiting, pruritus, and urinary retention occurred only in the epidural group, whereas nausea occurred significantly less frequently in the extrapleural group. We conclude that after thoracotomy continuous extrapleural intercostal nerve block is as effective as lumbar epidural morphine in reducing postoperative pain and restoring pulmonary mechanics. Because of the significantly lower complication rates we favor continuous extrapleural intercostal nerve block for postthoracotomy analgesia.

Adult↗
PubMed1993

Pilot trial of a gonadotropin hormone agonist with replacement hormones as a prototype contraceptive to prevent breast cancer.

Combination oral contraceptive (COC) users have reduced risks of ovarian and endometrial cancer, but COCs have not reduced breast cancer risk. We have previously argued that a hormonal contraceptive with substantially lower doses of sex-steroids should reduce breast cancer risk by decreasing the breast epithelial cell proliferation below usual premenopausal levels. We report here the preliminary results of a pilot trial with such a prototype contraceptive consisting of an agonist of gonadotropin releasing hormone (GnRHA) administered with low doses of an oral estrogen (0.625 mg of conjugated estrogen, CE, for 6 days every week) and intermittent oral progestogen (10 mg of medroxyprogesterone acetate, MPA, for 13 days every 4 months). Eighteen subjects at five-fold or greater increased breast cancer risk were entered and randomized -12 to the contraceptive arm and 6 to a control arm. The principal endpoints included tolerance of the regimen, vaginal bleeding patterns, and the regimen's effect on the endometrium, bone metabolism, and lipids. A symptom questionnaire was used to assess tolerance; the contraceptive subjects had fewer symptoms following initiation of the regimen. This results from the elimination of symptoms associated with the luteal phase of the menstrual cycle, commonly referred to collectively as premenstrual syndrome, PMS. The few occurrences of hot flushes or vaginal dryness that did occur were eliminated by small increases in estrogen dose (0.9 mg CE). Scheduled vaginal bleeding occurred associated with most periods of progestogen administration. Unscheduled bleeding or spotting was infrequent and decreased with time on the regimen. A beneficial rise in high-density lipoprotein cholesterol was evident in the contraceptive subjects. Despite the use of an estrogen dose which is known to prevent loss of bone mineral density in normal postmenopausal women, an annualized loss of 1.9% was seen in contraceptive subjects. It is hypothesized that this is secondary to inhibition of ovarian androgen production by the GnRHA, which may additionally account for changes in libido occasionally reported with GnRHA. The study continues with the addition of a small dose of androgen to replace that lost by the action of the GnRHA.

Adult↗
PubMed1993

Electron microscopic changes in human pulps after intraligamental injection.

Because of its advantages, intraligamental injection is becoming a popular anesthetic technique to achieve anesthesia in vital pulps. This study investigated the possible effects of intraligamental injection on human pulps under electron microscope. Forty-two mandibular and maxillary premolars were scheduled to be extracted for orthodontic reasons after being anesthetized with intraligamental injections of 2% lidocaine, 1:100,000 epinephrine (experimental group). The same anesthetic solution was used on the contralateral teeth with either nerve or field blocks (control group). To examine the effects of ischemia on odontoblasts, 12 anesthetized premolars were extracted, and their pulps were placed in physiologic saline solution for different time intervals (15 minutes to 6 hours). The teeth in the experimental and control groups were then reanesthetized with nerve or field blocks of 3% carbocaine without epinephrine after time periods that ranged from 15 minutes to 28 days. After extraction, the teeth were sectioned vertically and their pulps were fixed in 3% glutaraldehyde. The odontoblastic layer of each pulp was examined under electronic microscope. Nuclear and cytoplasmic changes started an hour after ischemia in the pulps placed in physiologic saline. In contrast, little or no cellular changes occurred in pulps of the experimental or controls groups. On the basis of the results, it appears that intraligamental injection has no long-term deleterious effects on pulps of young human premolars.

Anesthesia, Dental↗
PubMed1993

Estradiol regulation of secretory component: expression by rat uterine epithelial cells.

Sex hormones are known to play an important role in the regulation of mucosal immunity in the female reproductive tract. The purpose of this study was to examine the effect of estradiol (E2) on secretory component (SC) expression by epithelial cells in the rat uterus and to determine whether SC mRNA is present in uterine tissues and is under hormonal control. When ovariectomized rats treated with E2 for 3 days and sacrificed 12 h after the last injection, expression of SC on luminal and glandular epithelial cells, as determined by immunohistochemistry, was elevated when compared to control animals. To determine whether E2 regulation of SC involves mRNA synthesis, uterine RNA was extracted and analyzed by Northern blot. These experiments demonstrated that SC RNA is present in uteri from intact rats and markedly increased when ovariectomized animals are treated with E2. In other studies, uterine epithelial cells from adult rats were isolated and grown on permeable membranes for 5 to 10 days. Under these conditions, isolated epithelial cells grow to confluence, form tight junctions, and preferentially secrete SC into the apical medium. These studies identify epithelial cells as a key target cell in the uterus for the regulation of mucosal immunity by E2, which we postulate will play an important role in studies to prevent and/or control the spread of sexually transmitted diseases.

Animals↗
PubMed1993

The use of tissue adhesive in pulmonary resections.

One hundred eighty-seven consecutive patients underwent resection of primary bronchogenic carcinoma with intraoperative application of monomeric n-butyl-2-cyanoacrylate glue from July 1987 through December 1992. The glue reinforced either the stapled bronchial stump (135 patients), the sutured bronchial anastomosis in sleeve resections (37 patients) or the staple lines of wedge resections (15 patients). Mortality was 1.6% overall (3 of 187), and 5% among pneumonectomies (2 of 40). Bronchopleural fistulae occurred in 0.5% (1 of 187) of all pulmonary resections and 2.5% of pneumonectomies (1 of 40). There was no fistula in the lobectomy or sleeve resection groups. Bronchial anastomosis was accomplished in patients who underwent sleeve resection with four interrupted apposing sutures and airtight closure ensured by the tissue adhesive. There was no incidence of bronchial stenosis. There were no cyanoacrylate adhesive-related complications. A follow-up of the patients up to 68 months has indicated not only its effectiveness but also its safety. Monomeric n-butyl-2-cyanoacrylate glue is safe, offers protection to bronchial margins and may be valuable in preventing bronchial stenosis after sleeve resections.

Adolescent↗
PubMed1993

Social evaluation of health care versus personal evaluation of health states. Evidence on the validity of four health-state scaling instruments using Norwegian and Australian surveys.

In most of the cost-utility literature, quality-adjusted life-year (QALY) gains are interpreted as a measure of social value. Given this interpretation, the validity of different multi-attribute health-state scaling instruments may be tested by comparing the values they provide on the 0-1 QALY scale with directly elicited preferences for person trade-offs between different treatments (equivalence of numbers of different patients treated). Norwegian and Australian public preferences as measured by the person trade-off suggest that the EuroQol Instrument assigns excessively low values to health states. This seems to be even more true of the McMaster Health Classification System. The Quality of Well-being Scale appears to compress states toward the middle of the 0-1 scale. By contrast, the Rosser/Kind index fits reasonably well with directly measured person trade-off data.

Adult↗