Architectural and mechanical properties of the rat adductor longus: response to weight-lifting training

BACKGROUND

The primary objective of this study was to determine the effects of an 8 week weight-lifting program on the mechanical, histochemical, and architectural properties of the rat adductor longus muscle, a predominantly slow adductor muscle.

METHODS

The weight-lifting program was progressive such that the rats were performing three bouts of ten lifts with 300% body weight load every other day during the last 3 weeks of training. The in situ mechanical properties, fiber type composition, and architectural characteristics of the muscle were determined in control and weight-trained rats. Intramuscular electromyographic recordings were used to verify the recruitment of the adductor longus during the lifting task.

RESULTS

The adductor longus was composed predominantly of slow fibers (approximately 80% slow oxidative) and had a relatively simple architectural design, i.e., one motor end-plate band near the center of the muscle, virtually no angle of pinnation of the fibers from the line of pull, and a fiber length:muscle length ratio of 0.72. The mean fiber type composition and fiber size, the total fiber number, and the mean physiological cross-sectional area of the adductor longus were similar in the two groups of rats. The mean body weight of weight-lifting rats was significantly less than control. The weight of the adductor longus relative to body weight and its fatigue resistance were higher and the maximum rate of shortening was slower in weight-lifting than in control rats. No other mechanical property was significantly affected by the training program.

CONCLUSIONS

The results indicate that approximately 1 minute of over-load every other day by physiological recruitment of motor units can induce remodeling of the adductor longus of growing rats; i.e., the trained muscles were slower and less fatigable than control. Given that the effects on the architectural or force-generating properties of the muscles were small, the marked improvement in the ability to lift heavier loads as the training progressed appears to be more attributable to neurally related than to muscle-related phenomena.

Ovarian luteal cell toxicity of ethylene glycol monomethyl ether and methoxy acetic acid in vivo and in vitro

These studies define the site and mechanisms of reproductive toxicity of ethylene glycol monomethyl ether (EGME) in a nongravid female animal model using in vivo and in vitro methods. In vivo studies assessed vaginal cytology and histology, ovarian histology, and serum hormones in 80- to 90-day-old, adult, regularly cycling, female Sprague-Dawley rats treated daily with EGME or vehicle by oral gavage. Dose-response and time-course studies (four to nine rats per group per treatment) determined that 300 mg/kg EGME suppressed cyclicity without systemic toxicity within 3 to 8 days, and doses less than 100 mg/kg had no effect. Pathogenesis studies (six to nine rats per time and treatment) determined that 300 mg/kg EGME elevated serum progesterone within 32 hr after dosing, while serum estradiol, FSH, LH, and prolactin remained at baseline levels. In EGME-treated rats, cyclicity was suppressed, ovulation was inhibited, and corpora lutea were hypertrophied. Thus, EGME appeared to target the ovarian luteal cell. To further examine the toxicity in vitro, luteal cells were recovered from 23-day-old, hCG-primed Sprague-Dawley rats and treated with 0-10 mM methoxy acetic acid (MAA), the proximate toxic metabolite of EGME. MAA (1-10 mM) maintained elevated progesterone levels as production declined in untreated cells at 24 and 48 hr of culture. Progesterone production was maintained independent of LH-stimulated cAMP levels. MAA decreased ATP, but only at 48 hr and at 2.5 mM or greater concentrations. Thus, these studies establish that the ovarian luteal cell is a target of EGME and MAA in vivo and in vitro and that the effect on luteal cell progesterone production is likely independent of LH-stimulated cAMP pathways.

Attitudes toward obstetrics training. Residents surveyed at McGill University and University of Montreal

OBJECTIVE

To determine family medicine residents' attitudes toward family practice training in obstetrics and neonatology before and after implementation of a modified obstetrics curriculum at McGill University (MG).

DESIGN

Two-group pretest and posttest. Fifty-seven respondents, 31 at MG, 26 at University of Montreal (UM), were case matched as first-year and second-year residents.

SETTING

Departments of Family Medicine at MG and UM.

PARTICIPANTS

Family medicine residents at MG and UM.

INTERVENTION

A modified obstetrics curriculum was introduced at MG (study group); no modifications were introduced at UM (control group). First- and second-year residents' attitudes toward the adequacy of training were assessed through responses to a questionnaire administered in July 1992 and July 1994.

MAIN OUTCOME MEASURES

Changes in response scores before and after implementation of the modified curriculum.

RESULTS

Repeated multivariate analysis of variance (MANOVA) showed respondents believed family practice obstetrics training was adequate in general, but that family practitioners were inadequately trained in emergency obstetric skills. Scores for items assessing neonatology skills increased significantly in the MG group after the intervention.

CONCLUSIONS

Residents' overall confidence in their obstetrics training did not appear to improve, but this might be due to a time lag between curriculum modification and attitudinal change. McGill residents' confidence in neonatology skills improved significantly after curriculum modification.

Agenesis of the corpus callosum in Turner syndrome with ring X

An 8-year-old girl with Turner syndrome and 45,X/46,X,r(X) mosaicism was found to have agenesis of the corpus callosum and various other characteristics including 'kabuki makeup' facial features and mild learning disability. Only two other cases of Turner syndrome associated with agenesis of the corpus callosum have been reported, both in patients with a 45,X karyotype. In both of those patients the constellation of signs differed from those of the present patient in a number of ways. It remains to be confirmed whether there is a higher incidence of CNS malformation in girls who have Turner syndrome with a ring X than has been reported for girls with Turner syndrome in general.

Suicidal adolescents after hospitalization: parent and family impacts on treatment follow-through

OBJECTIVE

To help determine optimal strategies for treating suicidal adolescents, the authors studied family predictors of compliance with recommended psychotropic medication monitoring, individual therapy, and parent guidance/family therapy sessions.

METHOD

Sixty-six hospitalized, suicidal adolescents participated in a comprehensive diagnostic evaluation and depression/suicidality assessment. Family/parental assessment measures were the Family Assessment Device, Social Adjustment Inventory for Children and Adolescents (parent-adolescent subscales), Symptom Checklist-90-Revised, and Social Adjustment Scale-Self Report. Follow-up evaluation, 6 months posthospitalization, consisted of structured telephone interviews assessing treatment follow-through.

RESULTS

Compliance with recommended medication follow-up (66.7%) and individual therapy (50.8%) was better than compliance with parent guidance/family therapy (33.3%) sessions. The most dysfunctional families and those with the least involved/affectionate father-adolescent relationships had the poorest follow-through with parent guidance/family therapy. Mothers' depressive and paranoid symptoms were linked with less adolescent individual therapy and family therapy follow-through. Mothers' hostility was associated with less medication follow-up.

CONCLUSIONS

Follow-through was best for medication and individual therapy. Multiple family/parental predictors of poor follow-through suggest the need for alternative or supplemental treatment strategies.

Effect of salmeterol on Pseudomonas aeruginosa infection of respiratory mucosa

We have studied the effect of salmeterol on both P. aeruginosa interactions with the mucosa of nasal turbinate organ cultures and on pyocyanin-induced (20 microg/ml) and elastase-induced (100 microg/ml) damage to nasal epithelial cells. Organ cultures were exposed to salmeterol either by preincubation with 4 x 10(-7) M salmeterol for 30 min or by pipetting 20 microl of 4 x 10(-7) M salmeterol onto the organ culture surface immediately prior to bacterial inoculation. Infected organ cultures (8 h) had significantly (p < or = 0.01) increased epithelial damage, and P. aeruginosa was predominantly associated with damaged epithelium and mucus. Salmeterol significantly (p < or = 0.02) reduced epithelial damage caused by infection and the total number of adherent bacteria (p < or = 0.05), but bacterial distribution on the mucosa was unchanged. Nasal epithelial cells incubated with pyocyanin (20 microg/ml) or elastase (100 microg/ml) for 3 h had significantly (p < or = 0.05) increased cytoplasmic blebbing and mitochondrial damage versus control values. Elastase also significantly (p < or = 0.05) increased cell projection and reduced the level of ciliation. Cells preincubated with salmeterol (2 x 10(-7) M) showed a significant reduction in some features of cell damage caused by both toxins, which was inhibited by the beta2-adrenoceptor antagonist propranolol. Our results indicate that salmeterol reduces P. aeruginosa-induced damage to both organ culture and nasal epithelium.

Introduction of wireless, pen-based computing among visiting nurses in the inner city: a qualitative study

The purpose of this qualitative study is to understand how a sample of visiting nurses experienced the practice of home health nursing in the inner city and how they perceived the anticipated introduction of wireless, pen-based computing into their practice. Focus groups were held with visiting nurses 1 week before the introduction of the wireless, pen-based computers. The data were analyzed using Strauss and Corbin's (1990) method for concept development. The following central concepts emerged from the focus groups with visiting nurses: "Missing contact in the field," "Consumption of time writing on forms," "Using the computer to help with the practice of home health nursing," and "Home nursing is a lifeline." These concepts, based on the commentaries by visiting nurses, help one to understand the problems encountered by visiting nurses in the delivery of home health care, identify ways to incorporate evolving technologies to enhance nursing practice, and consider approaches to computer skill acquisition.

Outpatient treatment with epirubicin and oral etoposide in patients with small-cell lung cancer

To assess the efficacy and toxicity of an outpatient combination chemotherapy in small-cell lung cancer (SCLC), we treated 70 consecutive patients with epirubicin 80 mg m(-2) i.v. on day 1 and etoposide 200 mg o.d. p.o. on days 1-4 (EE) at 3-weekly intervals. The median age of patients was 64 years (range 39-84). The male-female ratio was 42:28 and 35 (50%) had metastatic disease. Fifty-seven patients were evaluable for response. The overall response rate was 64.4%, including 14 (23.7%) complete responses and 24 (40.7%) partial responses. Median time to progression was 7 months in responders and 8 months in patients with limited disease. The median survival in patients with limited disease was 10.5 months (range 0.5-70 +) and 7 months (range 0.5-24) in those with extensive disease. Improvement of symptoms occurred in 79% of patients with shortness of breath, 80% with cough, 81% with haemoptysis and 68% with pain. In 19 patients an increase in body weight was noted. Major (WHO grade 3/4) toxicities were neutropenia in 13 (18.5%) patients, alopecia in 33 (47.1%) patients, mucositis in 15 (21.4%) patients, anorexia in eight patients (11.4%), nausea and vomiting in six patients (8.5%) and diarrhoea in 4 (5.7%) patients. In conclusion, EE is an active and well-tolerated outpatient regimen in the treatment of SCLC. The survival data in this unselected group of patients were disappointing and the possible explanations for this are discussed.

Electrochemiluminescence flow injection immunoassay for atrazine

Antibodies to atrazine were labelled with glucose oxidase and used in colorimetric enzyme linked immunosorbent assays. Transparent aminosilanized indium tin oxide coated glass electrodes were derivatized with aminodextran covalently modified with atrazine caproic acid. The labelled antibodies were used to investigate the derivatized electrodes colorimetrically and the electrodes were use in an electrochemiluminescence flow injection analyser. Electrochemiluminescence immunoassay for atrazine in the range 0-10 ppb showed that it was possible to detect less than 0.1 ppb, the precautionary limit for pesticides in drinking water recommended by the European Commission.

Monocyte chemoattractant protein-1: receptor interactions and calcium signaling mechanisms

Monocyte chemoattractant protein-1 (MCP-1) is a member of the Cys-Cys chemokine family. Two related MCP-1 receptors have been identified (CC-CKR2A and CC-CKR2B), although the precise kinetics of ligand binding and calcium signaling of these receptors has yet to be investigated. To examine this more closely, the human MCP-1 receptors were cloned and expressed in Chinese hamster ovary (CHO) cells. Membranes prepared from cells expressing CC-CKR2B bind MCP-1 selectively and with high affinity (Kd = 120 pM). MCP-1 stimulation of recombinant CHO cells expressing CC-CKR2B induces a rapid increase in intracellular Ca2+ through both receptor-operated Ca2+ channels and mobilization of Ca2+ from intracellular stores, and leads to a rapid temperature-dependent internalization of the ligand/receptor complexes. In contrast, recombinant CHO cells expressing CC-CKR2A, and membranes prepared from these cells, fail to bind detectable levels of MCP-1. However, MCP-1 stimulation of cells expressing CC-CKR2A induces a small but significant increase in intracellular Ca2+. Repeated stimulation of these cells with MCP-1 leads to a potentiation of the response to a level comparable to that seen in cells expressing CC-CKR2B. These observations suggest that the levels of cell surface CC-CKR2A are controlled by novel mechanisms.

Socioeconomic circumstances and the risk of bowel cancer in Northern Ireland

OBJECTIVE

To describe the variation in the incidence of colorectal cancer across Northern Ireland and relate it to factors associated with community deprivation.

DESIGN

This was a cross sectional descriptive study.

SETTING

Incidence data were obtained from a population based register for the period 1990-91. Small areas were characterised by their "affluence", or lack of it, by deriving a Townsend deprivation score for each electoral ward, using information from the 1991 census. PARTICIPANTS, MAIN OUTCOME MEASURES, AND STATISTICAL METHODS: The age standardised incidence was calculated for all colorectal cancer cases diagnosed histologically in 1990-91. Electoral wards were grouped into quintiles of the population after ranking of their Townsend scores and the association with incidence was studied using Poisson regression.

RESULTS

The age standardised colorectal cancer incidence ranged from 22.5 (for quintile 1) to 29.9/100,000 (quintile 5) for men but the trend for women was less regular and rates were 18.4, 23.8, 27.3, 26.5, and 23.9/100,000 for quintiles 1-5 respectively (that is, from the most "affluent" to the most "deprived" fifths of the population). After adjusting for age and sex in Poisson regression, there was a significant association between the total colorectal cancer incidence and levels of community deprivation. The rate ratio for the most deprived quintile of the population (compared with the least) was 1.28 (95% CI 1.06,1.53). The effect was stronger for rectal cancer than for colonic cancer. There was no association between community deprivation and the cancer stage at diagnosis.

CONCLUSIONS

In this population, the colorectal cancer incidence is associated with the level of material deprivation. The disease stages at the time of diagnosis in patients from more deprived areas seem to be comparable with those of patients from affluent areas. As others have shown, associations such as these are not explicable entirely on the basis of the distribution of known risk factors. Further research is needed to determine plausible mechanisms for the association.

The effect of mutations in genes required for lipopolysaccharide synthesis on Haemophilus influenzae type b colonization of human nasopharyngeal tissue

Haemophilus influenzae type b (Hib) is an upper respiratory tract commensal that can cause invasive disease, particularly in young children. Lipopolysaccharide (LPS) has been implicated as a major virulence determinant of Hib, and changes in LPS structure may influence bacterial interactions with the respiratory mucosa. We have examined the effect of variations in LPS on the interaction of Hib with human nasal turbinate tissue maintained in an organ culture model with an air-interface, by using isogenic derivatives of strains RM153 (Eagan) and RM7004 expressing truncated LPS due to mutations in genes contained within the chromosomal loci lic1 and lic2 (lic1lic2) or in the galE and galK genes (galEK). Tissue was infected with an inoculating dose of 2.3-3.3 x 10(6) colony forming units (cfu) in 2 microliters of PBS and maintained for 24 h. By scanning electron microscopy the percentage of the organ culture surface exhibiting epithelial damage increased from 5.3 +/- 1.4 in controls to 12.5 +/- 6.4-26.3 +/- 9.1 following infection, with no significant difference between parent strains and their derivatives. There was significant bacterial tropism for mucus, and to a lesser extent damaged cells, which was not influenced by the LPS phenotype. All strains caused separation of epithelial cells, adhered to non-luminal cell surfaces, and invaded the epithelium intercellularly. We conclude that Hib associated with mucus and damaged epithelium, and infrequently with normal epithelium, but changes in the LPS phenotype did not affect the interaction between Hib and the mucosal surface of human nasal turbinate tissue.

Peripheral morphine analgesia: synergy with central sites and a target of morphine tolerance

Morphine injected s.c. in the tail is a potent analgesic in the tail-flick assay when the radiant heat source is focused directly over the injection site (ED50, 4.5 micrograms), but not if the radiant heat source is moved 1 cm proximally or distally to the injection site. Naloxone given systemically reverses this peripheral analgesia. Antisense oligodeoxynucleotides directed against exons 1 and 4 of MOR-1, a cloned mu opioid receptor, administered intrathecally (i.t.) block the local analgesic effect of morphine in the tail, indicating that the local response is mediated through mu receptors located on the terminals of sensory neurons from the dorsal root ganglia. Combinations of morphine given locally in the tail and spinally (i.t.) are synergistic. Spinal morphine also synergizes with systemic morphine in analgesia assays. Supraspinal morphine enhances systemic morphine analgesia, but less dramatically. We also examined tolerance on these analgesic systems by using a daily morphine injection paradigm which shifts the dose-response curve for systemic morphine approximately 2-fold after 5 days. In this paradigm, morphine's analgesic potency after either supraspinal or spinal administration alone does not change. However, the dose-response curve for local morphine in the tail is shifted by over 19-fold. The analgesic activity of the combination of supraspinal and systemic morphine is lowered approximately 2-fold and the combination of i.t. and systemic morphine by 12-fold. These studies confirm the presence of a peripheral mechanism for morphine analgesia mediated by mu receptors located on sensory neurons from the dorsal root ganglia, which is extremely sensitive to chronic morphine dosing.

Family physicians and smoking cessation. Survey of practices, opinions, and barriers

OBJECTIVES

To assess what family physicians need to promote smoking cessation by looking at current knowledge, attitudes, and behaviours and to examine the barriers facing physicians in implementing an effective antismoking strategy.

DESIGN

Cross-sectional study involving face-to-face interviews and mailed questionnaires.

SETTING

Family practices in Kingston, Ont, and surrounding areas.

PARTICIPANTS

All family physicians (n = 155) in the City of Kingston and the counties of Frontenac, Lennox, and Addington.

MAIN OUTCOME MEASURES

Knowledge, attitudes, beliefs, and practices concerning smoking cessation; barriers and practices recommended in the literature.

RESULTS

Response rate was 77%. Many physicians know about smoking cessation, and many actively counsel their patients to quit. Brief advice, nicotine replacement therapy, self-help materials, and follow-up appointments are the most common methods. Although many report that they are already knowledgeable, many are willing to learn more. Many physicians have unrealistically high estimates of the probability of success, and many find poor compliance among patients to be the greatest barrier.

CONCLUSIONS

Family physicians in this are recognize the need to help their patients to quit and are identifying and counseling smokers in their practices. The main educational need could be to appreciate smoking as an addictive behaviour.

Intestinal base excretion in the seawater-adapted rainbow trout: a role in acid-base balance?

A potential role for the intestine of seawater-adapted teleosts in acid&shy;base regulation was investigated following earlier reports of highly alkaline rectal fluids in the gulf toadfish Opsanus beta. Rectal samples taken from starved seawater-adapted rainbow trout had a high fluid pH (8.90&plusmn;0.03; mean &plusmn; s.e.m., N=13) and base (HCO3-+2CO32-) content of 157&plusmn;26 mequiv kg-1 (N=11). In trout fitted with rectal catheters, rectal fluid was voided at a rate of 0.47&plusmn;0.11 ml kg-1 h-1 (N=8), giving a net base excretion rate of 114&plusmn;15 &micro;equiv kg-1 h-1 (N=7). Drinking rates averaged 3.12&plusmn;0.48 ml kg-1 h-1 (N=8), and accounted for only 6 % of the base excreted via the intestine, indicating substantial net transport of endogenously derived base into the intestine. Rectally excreted base was approximately balanced by an equivalent efflux of net acid from non-rectal sources (possibly as NH4+ excretion via the gills). Samples taken from four sites along the intestine revealed that the most anterior region (the pyloric intestine) was responsible for the majority of HCO3-+2CO32- accumulation. The pyloric intestine was subsequently perfused in situ to investigate possible mechanisms of base secretion. Net base fluxes were found to be dependent on luminal Cl-, 76 % stimulated by amiloride, 20 % inhibited by 10(-4) mol l-1 acetazolamide, but unaffected by either 10(-4) mol l-1 SITS or 2x10(-5) mol l-1 DIDS. This suggests that the mechanism of base secretion within the pyloric intestine may involve a Cl-/HCO3--ATPase. It is speculated that intestinal base secretion may play a role in facilitating osmoregulation of seawater-adapted teleosts.

Mapping of the H7-serospecific domain of Escherichia coli flagellin

The amino acid sequences responsible for H7 and H23 flagellum serology have been identified by using a genetic approach. The H7-specific domain was located between amino acids 352 and 374 of the H7 flagellin. The sequencing data also demonstrated that the difference between the H7 and H23 flagellins in this region results from a single substitution at amino acid 366 (Ser-->Thr). The common epitopes for H7 and H23 were located between amino acids 284 and 366.

Generation and analysis of 280,000 human expressed sequence tags

We report the generation of 319,311 single-pass sequencing reactions (known as expressed sequence tags, or ESTs) obtained from the 5' and 3' ends of 194,031 human cDNA clones. Our goal has been to obtain tag sequences from many different genes and to deposit these in the publicly accessible Data Base for Expressed Sequence Tags. Highly efficient automatic screening of the data allows deposition of the annotated sequences without delay. Sequences have been generated from 26 oligo(dT) primed directionally cloned libraries, of which 18 were normalized. The libraries were constructed using mRNA isolated from 17 different tissues representing three developmental states. Comparisons of a subset of our data with nonredundant human mRNA and protein data bases show that the ESTs represent many known sequences and contain many that are novel. Analysis of protein families using Hidden Markov Models confirms this observation and supports the contention that although normalization reduces significantly the relative abundance of redundant cDNA clones, it does not result in the complete removal of members of gene families.

Multicenter study of target-controlled infusion of propofol-sufentanil or sufentanil-midazolam for coronary artery bypass graft surgery. Multicenter Study of Perioperative Ischemia (McSPI) Research Group

BACKGROUND

The use of target-controlled infusions of anesthetics for coronary artery bypass graft surgery has not been studied in detail. The effects of target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were evaluated and compared.

METHODS

At 14 clinical sites, 329 patients were given a target-controlled infusion of propofol (n = 165) to produce effect-site concentration (Ce) of > or = 3-micrograms/ml or a target-controlled infusion of sufentanil (n = 164). Sufentanil or midazolam, respectively, also were infused. Systolic hypertension, hypotension, tachycardia, and bradycardia were assessed by measuring heart rate and blood pressure every minute during operation. Myocardial ischemia was assessed perioperatively by monitoring ST segment deviation via continuous three-lead Holter electrocardiography, and it was evaluated during operation by monitoring left ventricular wall motion abnormality via transesophageal echocardiography.

RESULTS

The measured cardiovascular parameters were satisfactory and usually similar for the patients receiving propofol-sufentanil or sufentanil-midazolam. The primary endpoint of the percentage of patients with intraoperative ST segment deviation (23 +/- 6% vs. 24 +/- 6%, P = 0.86) did not differ significantly between the two groups. The incidence of left ventricular wall motion abnormality shown on transesophageal echocardiography before (19 +/- 4% vs. 26 +/- 4%, P = 0.25) and after (23 +/- 4% vs. 31 +/- 5%, P = 0.32) cardiopulmonary bypass also did not differ significantly for the two groups. Changes in intraoperative target concentration were more frequent with propofol-sufentanil anesthetic than with sufentanil-midazolam (11.7 +/- 7.1 vs. 7.3 +/- 3.6, P < 0.001). The incidence of intraoperative hypotension (77% vs. 55%, P < 0.001), the use of inotropic/vasopressor medications (93% vs. 84%, P = 0.01), and the administration of crystalloids (2.8 +/- 1.4 L vs. 2.4 +/- 1.2 L, P < 0.001) were significantly greater in the propofol-sufentanil group. Conversely, the incidence of intraoperative hypertension (43% vs. 54%, P = 0.05) and the use of antihypertensive/vasodilator medications (70% vs. 90%, P < 0.001) were significantly less in the propofol-sufentanil group.

CONCLUSIONS

Target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were suitable to provide anesthesia for coronary artery bypass graft surgery. Continuous monitoring revealed a high prevalence of hemodynamic abnormalities. Despite greater hypotension in the propofol-sufentanil group and greater hypertension in the sufentanil-midazolam group, episodes of myocardial ischemia were similar for both groups and were not temporally related to episodes of hemodynamic abnormalities.