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Biomedical subjects

A M Smith

Publications and source records attributed to A M Smith.

At least 109 records · Page 6Linked to original sources
PubMed1999

Impact of the surface slipperiness of grasped objects on their subsequent acceleration.

Seven subjects were asked to reach and grasp an object between the thumb and index finger, lift it about 30 cm high and 25 cm forward from one table to another, at their preferred speed. The perpendicular grip force and the tangential load force applied to the contact surface were digitized at 500 Hz and stored on a laboratory computer. The trajectory of the wrist and of the object was recorded using four infrared cameras tracking the movement of reflective markers attached to the distal styloid process of the radius and on the top of the object. The aim of this study was to demonstrate the influence of low friction (i.e. surface slipperiness) on the acceleration of the wrist. Friction was reduced by coating the smooth brass grasping surface with talc. The seven subjects had skin to surface coefficients of friction which ranged from 0.52-1.18 for dry brass and 0.24 0.34 for talc-coated brass. Two weights (418 and 1070 g) were used with each surface. The results indicated that with the slippery surface the necessary higher grip force/load force ratio was produced by an increase in the grip force and by a decrease in the wrist acceleration and a consequent reduction in the load force. This strategy was observed for both weights over a range of grip strengths between 21-98% of the individual's maximum voluntary contraction (MVC). This implies that even with adequate grip force reserves the reduction in acceleration is an acceptable and probable alternative solution to the force control problem. Our results also suggested that the loading rate and the object acceleration were planned and controlled together which emphasizes the role played by a predictive mechanism in organizing the kinematics of movements involving hand-held objects. This study shows that friction of the grasping surface not only affects the prehensile force dynamics, but it also influences the kinematics of the entire upper limb.

Acceleration↗
PubMed1999

Peritoneal dialysis-associated peritonitis caused by Propionibacteria species.

There are an increasing number of reports about unusual causes of peritonitis in peritoneal dialysis (PD) patients. The Propionibacteria species is a microorganism that is a normal skin flora. Under the presence of certain risk factors, it may produce serious infections. Patients at risk of having Propionibacteria sp infections have malignancy, diabetes mellitus, foreign bodies, or immunodeficiency. We describe a PD-associated peritonitis in a 51-year-old woman that was caused by Propionibacteria sp. This patient's risk factors for developing Propionibacteria sp peritonitis include a history of CREST syndrome, malignancy of the breast, and recent catheter surgery. To our knowledge, this is the first case of a PD-associated peritonitis caused by Propionibacteria sp reported in the literature.

Breast Neoplasms↗
PubMed1999

Women issues in female patients receiving peritoneal dialysis.

About 50% of the population receiving peritoneal dialysis (PD) in the United States are women. Nephrologists generally address medical issues related to end-stage renal disease, ie, anemia, hypercholesterolemia, secondary hyperparathyroidism. In female PD patients, specific topics should also be addressed. They include menstruation, birth control methods, osteoporosis, child bearing, postmenopausal hormone replacement and its consequences, screening of gynecological malignancies, sexual problems, and hemoperitoneum. We briefly describe in a multidisciplinary view the management of these issues.

Adult↗
PubMed1999

Making starch.

Improvements in understanding the structure of the starch granule and the nature and roles of starch-synthesising enzymes have allowed detailed mechanisms of the synthesis of the amylopectin and amylose components of the granule to be suggested. However, none of these proposed mechanisms has yet been shown to operate in vivo. Several critical aspects of granule synthesis, including granule initiation and the formation of the growth rings, remain a mystery.

Amylopectin↗
PubMed1999

Personal and social factors influencing age at first sexual intercourse.

Early initiation of sexual activity is a concern, in part because of increased risk of sexually transmitted diseases, including HIV, and unwanted pregnancies among young people. In this study, 241 high schoolers were administered a questionnaire to establish the relationships between age at first sexual intercourse and personal qualities (sexual style, attractiveness, physical maturity, restraint, autonomy expectations, and attitudes to gender roles), smoking and drug use, and aspects of the social context (social activities, media impact, peer norms). There were few effects of sex of respondent and none in which respondents' sex impacted on age of initiation. Overall (and among the male sample), perceptions of greater physical maturity, greater use of uncommon (mostly illicit) drugs, and expectations of earlier autonomy significantly differentiated between early and later initiators. This group of factors tends to confirm the view that early experience of sexual intercourse is correlated with problem behaviors and a press toward "adult" behaviors. For girls, this pattern was even clearer, with use of uncommon drugs being replaced as a significant contributor to early sexual experience by relative lack of restraint. We conclude that the desire to achieve the transition to adulthood at an earlier age than their peers constitutes a powerful incentive for young people to become sexually active.

Adolescent↗
PubMed1999

Surveillance for Barrett's oesophagus in the UK.

BACKGROUND: Endoscopic screening for Barrett's oesophagus is being offered without evidence of efficacy Barrett's oesophagus is not an ideal candidate for a screening programme, as the natural history is unclear, uncertainties surround the indication for intervention and the treatment is associated with high morbidity and mortality rates. METHODS: To determine the practices that clinicians employ in the management of Barrett's oesophagus in the UK, postal questionnaires were sent in May 1997 to 297 randomly selected members of the British Society of Gastroenterology asking for details of their current practice. RESULTS: Of 152 respondents, 106 (70 per cent) performed surveillance for Barrett's oesophagus; 46 (30 per cent) did not carry out screening. There was no difference in the practices carried out by physicians or surgeons, teaching or acute general hospital clinicians, or those with an upper gastrointestinal interest. There was a wide disparity in screening interval: just over half (52 per cent) screen at yearly intervals. Only nine (8 per cent) took four quadrant biopsies per 2 cm of Barrett's oesophagus. Nearly half (49 per cent) manage mild dysplasia by increasing the frequency of endoscopy; only seven (7 per cent) prescribed patients a proton pump inhibiting agent. Faced with severe dysplasia, 33 (31 per cent) offered surgery immediately; 22 (21 per cent) simply followed the patient by endoscopy. Those not choosing to perform screening most frequently cited lack of evidence of efficacy as the reason behind their decision. CONCLUSION: There is wide variation in surveillance practices for Barrett's oesophagus. Some methods are ineffectual. The recommendations made by the Barrett's Oesophagus Working Party in 1991 are not followed, possibly because they are not practical. New workable guidelines based on available evidence and a consensus of expert opinion should be established; this was suggested by 38 per cent of respondents who performed screening.

Barrett Esophagus↗
PubMed1999

Efficient presentation of house dust mite allergen Der p 2 by monocyte-derived dendritic cells and the role of beta 2 integrins.

Monocyte-derived dendritic cells (MDDC) are potent antigen-presenting cells (APC). The APC functions of MDDC in allergy were examined. MDDC presentation of the major house dust mite allergen Der p 2 resulted in 4-12-fold higher T-cell proliferation and markedly higher IFN-gamma and IL-5 production than PBMC cultures. Comparable T-cell proliferation was obtained with 10-fold fewer MDDC than purified monocytes. MDDC cultured from adherent cells, or CD14+, CD11b+ or Percoll-purified monocytes were comparable in presenting soluble Ag, and in stimulating allogeneic MLR. Importantly, MDDC presentation of Der p 2 resulted in both Th1 and Th2 stimulation, although MDDC are known to produce high levels of IL-12 and stimulate biased Th1 responses. The basis for the potent APC function of MDDC was further examined. MDDC were found to be highly phagocytic. Immunoprecipitation studies showed markedly elevated ICAM-1 expression but > 10-fold reduction in LFA-1 expression on MDDC compared with monocytes. Monoclonal antibody (MoAb)-blocking experiments showed that ICAM-LFA-1 interaction was essential for MDDC stimulation of Der p 2-specific T-cell proliferative responses. These results show that the use of MDDC as APC provides a simple, sensitive and versatile method for detecting T-cell responses to allergens and that the strong phagocytic capability and the increased ICAM-1 expression of MDDC contribute significantly to their Ag presentation potency.

Allergens↗
PubMed1999

Endoscopic release of the carpal tunnel: a technical note.

The Agee technique is a standard approach for the endoscopic release of the carpal tunnel. We describe a modification of the technique. This involves dilatation of the path for the blade assembly with urethral dilators. This permits a graded dilatation of the path. We believe it creates a track of more uniform width. It also provides more accurate information about the tightness of the carpal tunnel. Its adoption may reduce the chance of nerve injury.

Carpal Tunnel Syndrome↗
PubMed1999

Introduction to adult posttraumatic osteomyelitis of the tibia.

The tibia is the most frequent site of an open fracture, and treatment of adult posttraumatic osteomyelitis of the tibia represents a significant clinical problem that has been recognized for centuries. Ancient modalities such as immobilization and debridement are still mainstays of therapy, and recent developments such as the use of antibiotics and muscle transfer have helped to improve outcome. Osteomyelitis is classified based on the Cierny-Mader system to provide prognostic and therapeutic information. Open fractures can be classified by the Gustilo system, again providing prognostic and therapeutic data. Gustilo Type III fractures have a high likelihood of having infection develop. Treatment principles include immobilization, thorough debridement, control of infection through antibiotic use, control of dead space, and soft tissue coverage.

Adult↗
PubMed1999

A longitudinal examination of athletes' emotional and cognitive responses to anterior cruciate ligament injury.

OBJECTIVE: To determine the emotional and cognitive impact of injury and surgery on physical recovery in injured athletes. DESIGN: A prospective longitudinal study comparing the psychosocial and physical recovery of competitive and recreational athletes. SETTING: Tertiary-care sports medicine center. PARTICIPANTS: Twenty-seven athletes (15 men and 12 women) who required anterior cruciate ligament (ACL) reconstruction surgery. INTERVENTIONS: A repeated-measures design used to compare the psychosocial and physical changes for 6 months after ACL surgery. MAIN OUTCOME MEASURES: Emotional (mood) and cognitive (coping) functions and physical recovery (range of motion, physician-rated level of recovery, and physician permission to return to sport). RESULTS: There was a significant time-effect difference in mood, with a greater mood disturbance and recovery rate for competitive athletes than recreational athletes. Differences in mood and pain coping were significant at 2 weeks and 2 months after surgery. CONCLUSION: Athletes experience significant mood changes throughout rehabilitation, which may hinder rehabilitation early in the process. Longer-term rehabilitation was not impacted by mood or pain coping. Future studies might focus on examining the process over a longer time period (1-2 years after surgery). Physicians should be aware of these findings and appropriately counsel and motivate athletes toward more favorable positive psychological and physical outcomes.

Adaptation, Psychological↗
PubMed1999

Uncertain knowledge: a national survey of high school students' knowledge and beliefs about hepatitis C.

OBJECTIVE: Hepatitis C (HCV) has recently emerged as an important public health issue. This study documents young people's hepatitis C (HCV) knowledge, risk perceptions and sources of information. METHOD: Australia, 1997; nationally representative survey; sample of students in Years 10 and 12 in government secondary schools (n = 3,550). RESULTS: Students' knowledge about HCV was found to be extremely poor. Of the seven questions on hepatitis, only one was answered correctly by more than half the students. Few could differentiate between hepatitis A, hepatitis B and hepatitis C. Only a small number (12%) perceived themselves to be at risk of hepatitis and fewer than half (41%) had sought advice about hepatitis. CONCLUSION: There is a need for more HCV education and health promotion for secondary school students. IMPLICATIONS: Some lessons from HIV education can be readily transferred to this new epidemic but others cannot. There is a danger that HIV and HCV will be conflated in education programs.

Adolescent↗
PubMed1999

Same-sex attraction, drug injection and binge drinking among Australian adolescents.

OBJECTIVE: To document the prevalence of same-sex attraction among students in years 10 and 12 in Australian Government high schools and to assess the association between same-sex attraction, binge drinking and drug injection. METHOD: Cross-section survey by anonymous, self-administered questionnaire of 3,387 students in Years 10 and 12 of the Government school system in Australia. RESULTS: Approximately 6% of respondents reported being currently attracted to members of their own sex. Being attracted to members of the same-sex was associated with more frequent binge drinking among boys and girls, and a three- to four-fold increase in the likelihood of reporting injecting drug use both over the lifetime and within the previous 12 months. CONCLUSIONS: Adolescents attracted to members of the same-sex report engaging in elevated levels of health-limiting behaviours. There is an urgent need for further research to document the reasons for this. It is recommended that health promotion activities directed at moderating young people's drug and alcohol practices explicitly acknowledge the over-representation of same-sex attracted young people in their target audience.

Adolescent↗
PubMed1999

Application of pbp1A PCR in identification of penicillin-resistant Streptococcus pneumoniae.

A seminested PCR assay, based on the amplification of the pneumococcal pbp1A gene, was developed for the detection of penicillin resistance in clinical isolates of Streptococcus pneumoniae. The assay was able to differentiate between intermediate (MICs = 0.25 to 0.5 microgram/ml) and higher-level (MICs = >/=1 microgram/ml) resistance. Two species-specific primers, 1A-1 and 1A-2, which amplified a 1,043-bp region of the pbp1A penicillin-binding region, were used for pneumococcal detection. Two resistance primers, 1A-R1 and 1A-R2, were designed to bind to altered areas of the pbp1A gene which, together with the downstream primer 1A-2, amplify DNA from isolates with penicillin MICs of >/=0.25 and >/=1 microgram/ml, respectively. A total of 183 clinical isolates were tested with the pbp1A assay. For 98.3% (180 of 183) of these isolates, the PCR results obtained were in agreement with the MIC data. The positive and negative predictive values of the assay were 100 and 91%, respectively, for detecting strains for which the MICs were >/=0.25 microgram/ml and were both 100% for strains for which the MICs were >/=1 microgram/ml.

Amino Acid Substitution↗
PubMed1999

A comparison of the therapeutic effectiveness of gastrin neutralisation in two human gastric cancer models: relation to endocrine and autocrine/paracrine gastrin mediated growth.

BACKGROUND: Gastrin is a growth factor for established tumours. AIMS: To investigate the therapeutic effect of antibodies, raised against the Gastrimmune immunogen, which neutralise the glycine extended and carboxy amidated forms of gastrin 17 in two human gastric cancer models. METHODS: MGLVA1 cells (which have a gastrin autocrine/paracrine phenotype) and ST16 cells (which have an endocrine phenotype) were injected into the peritoneal cavity of SCID mice. Peritoneal tumours, ascites, and cachexia formation occurred, with the monitored endpoint being morbidity. RESULTS: In MGLVA1 cells, intravenous administration of antibodies raised against Gastrimmune increased the 50% median survived by 25% at three different initial cell seeding concentrations (1 x 10(6)-5 x 10(5) per mouse). In ST16 cells, the effect of Gastrimmune induced antibodies on time to morbidity was greatest at the lowest cell seeding concentration (5 x 10(5) cells/mouse) with the 50% median survival increased by 74% and overall survival achieved in 38% of the mice. CONCLUSIONS: Gastrimmune may have potential therapeutic benefit on gastrin sensitive gastric tumours and may interact with both endocrine and autocrine mediated growth pathways.

Animals↗
PubMed1999

A model circulatory system for use in undergraduate physiology laboratories.

The cardiovascular system is a central topic in physiology classes, yet it is difficult to provide undergraduates with quality laboratory experiences in this area. Thus a model circulatory system was developed to give students hands-on experience with cardiovascular fluid dynamics. This model system can be constructed from readily available materials at a reasonable cost. It has a realistic pressure drop across the different vessels. Using this system, students can investigate the effect that blood volume, vessel compliance, vessel construction, and heart activity have on blood pressure and flow. The system also demonstrates the effect of vessel diameter on resistance and fluid velocity. This model may give students a more concrete, intuitive feel for cardiovascular physiology. Another advantage is that it allows dramatic and easily controlled manipulations with quantitative results. Finally, its simple construction allows students to interchange components, giving them greater flexibility in experimentation.

Cardiovascular Physiological Phenomena↗