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Biomedical subjects

M Lam

Publications and source records attributed to M Lam.

At least 55 records · Page 3Linked to original sources
PubMed1997

Factors affecting the severity of motor vehicle traffic crashes involving young drivers in Ontario.

OBJECTIVES: To assess the factors affecting the severity of motor vehicles traffic crashes involving young drivers in Ontario. POPULATION: Ontario young drivers, aged 16 to 20, involved in traffic crashes resulting in injury, between 1 January 1988 and 31 December 1993, on public roads in Ontario. METHODS: Population based case-control study. Cases were fatal injury, major injury, and minor injury crashes involving young drivers. Controls were minimal injury crashes involving young drivers. Cases and controls were obtained retrospectively from the Canadian Traffic Accident Information Databank. Unconditional logistic regression was used for data analysis. RESULTS: Factors significantly increasing the risk of fatal injury crashes include: drinking and driving (odds ratio (OR) 2.3), impairment by alcohol (OR 4.8), exceeding speed limits (OR 2.8), not using seat belts (OR 4.7), full ejection from vehicle (OR 21.3), intersection without traffic control (OR 2.2), bridge or tunnel (OR 4.1), road with speed limit 70-90 km/hour (OR 5.6) or 100 km/hour (OR 5.4), bad weather (OR 1.6), head-on collision (OR 80.0), and overtaking (OR 1.9). Results of the same model applied to major and minor injury crashes demonstrated consistent but weaker associations with decreasing levels of crash severity. CONCLUSIONS: A casual relationship between crash severity and the risk factors listed above was proposed. Risk factors recommended for preventive intervention include: alcohol consumption, speeding, and use of seat belts. Head-on collisions are of primary concern.

Accidents, Traffic↗
PubMed1997

An update on molluscum contagiosum.

Molluscum contagiosum is a common viral infection of the skin, and occasionally the mucous membranes, manifesting as benign tumors. The characteristic appearance is of pearly, umbilicated papules. The disease is self-limited in immunocompetent hosts, but may be protracted in those who are immunocompromised. Multiple local therapeutic options are available; the use of systemic agents has been reported in recalcitrant cases or in patients in whom topical therapy is difficult to apply.

Adolescent↗
PubMed1997

Hair casts: a case of pseudonits.

Hair casts are often misdiagnosed because of their close resemblance to nits from an infestation with pediculosis capitis. In their clinical presentation both of these disorders may appear to have white keratinous material adherent to hair shafts and can look very similar. Microscopic examination provides the definitive and correct diagnosis. We report a case of hair casts, also referred to as pseudonits.

Adult↗
PubMed1996

Bcl-2 inhibits hydrogen peroxide-induced ER Ca2+ pool depletion.

The mechanism by which Bcl-2 inhibits apoptosis is unknown. The Bcl-2 protein is localized to intracellular membranes, including the endoplasmic reticulum (ER). The ER is the major intracellular reservoir of Ca2+ in non-muscle cells, sequestering Ca2+ for use in intracellular signaling, and is a prime target of oxidative damage. Because of the recent suggestion that Bcl-2 acts in an antioxidant pathway, we wondered whether Bcl-2 might protect the ER Ca2+ pool in cells exposed to reactive oxygen species. To test this hypothesis, we assessed the effect of hydrogen peroxide (H2O2) treatment on the ER Ca2+ pool in WEH17.2 cells, which do not express Bcl-2, and two stable transfectants, W.Hb13 and W.Hb12. The Bcl-2 level by Western blotting is 4-fold higher in W.Hb12 cells compared to W.Hb13 cells. The ER Ca2+ pool in H2O2-treated and untreated cells was measured according to the amount of Ca2+ mobilized from the ER lumen into the cytoplasm by thapsigargin (TG), a selective inhibitor of the ER (Ca2+)-ATPase. H2O2 treatment produced a significant reduction in the TG-mobilizable Ca2+ pool in WEH17.2 and W.Hb13 cells, but not in W.Hb12 cells, indicating that overexpression of Bcl-2 preserves the integrity of the ER Ca2+ pool in cells exposed to reactive oxygen species.

Animals↗
PubMed1996

Outcome studies for burn patients in Hong Kong: patients' satisfaction.

With the recent advances in burns treatment, many more survive the burn to experience pain, scarring, physical deformity, loss of function and psychological trauma. Pressure therapy prescribed by occupational therapists for more than 20 years in Hong Kong has proved its effectiveness in treating the visible scars. However, the inconvenience and impaired appearance that is brought about by these garments during the long phase of therapy bears some weight in worsening patients' social acceptance and happiness in life, also their families especially in children. The objects of the studies were to measure the subjective rating of the effectiveness of pressure therapy through patients' satisfaction towards treatment effectiveness and its effect on daily life. Seventy cases with burn injuries over 1 year previously were selected randomly among the centres for the survey. The scale used was ordinal from 1 to 6. Eleven items concerning treatment effectiveness, life at home, work and leisure aspects were questioned. Results were analysed into two streams-satisfaction towards pressure therapy and change of life satisfaction pre- and post-injury. Non-parametric tests were used for data analysis. Through the Wilcoxon Sign Rank Test and Cluster analysis, major determinants were identified. These factors also showed significant correlation with this demographic data. The conclusions helped to evaluate and improve the existing service in both the garment properties and our scope of therapy for these patients, especially in work rehabilitation and finally (sexual) counselling which should be addressed by a team with interdepartmental support.

Activities of Daily Living↗
PubMed1996

Simultaneous manipulation of intestinal capacities and nutrient loads in mice.

To study the relationship between capacity and load in the small intestine, we simultaneously varied dietary nutrient load and intestinal capacity in mice. Intestinal transection alone caused an increase in intestinal mass, because of increased serosal mass. Because virgin mouse intestine possesses 180% reserve uptake capacity before resection and the intestine regenerates after resection, resection of up to 50% had no effect on food intake, digestive efficiency, intestinal brush-border glucose uptake rate, or mass of all organs measured except the cecum. Regeneration of intestinal mass and glucose uptake capacity was quantitatively complete, because intestinal mass 10 wk after resection was similar to that in unresected mice. Resected intestinal mass in lactating mice was four times larger than that immediately after resection in virgin mice. Cecal mass increased in 50%-resected lactating mice with high food intakes, suggesting nutrient spillage into the distal gut as a signal for regeneration. Mice failed to survive 70% resection of the intestine, possibly because intestinal reserve uptake capacity was exhausted immediately after surgery, making regeneration impossible.

Animals↗
PubMed1996

[Lawsuits against physicians in Chile].

Lawsuits against are becoming relevant in Chile. We analyzed 18 trials against physicians that occurred between 1977 and 1985 and that were ruled by Metropolitan Region courts. The causes of demands were death of patients in 8 trials and severe lesions in the rest. Twelve trials originated from surgical procedures (six from gynecological interventions), and nine came from private clinics. Nine trials lasted less than two years and three, more than 5 years. Sentence was pronounced by criminal courts in 12 cases and by appealing courts in six.

Chile↗
PubMed1995

Prevalence of intestinal parasites and association with symptoms in Southeast Asian refugees.

We prospectively evaluated 201 Southeast Asian refugees in a primary care clinic for intestinal parasites and their association with gastrointestinal symptoms. Patients completed a standardized screening questionnaire which elicited information on demographic factors and eight gastrointestinal symptoms, and stools were collected for ova and parasite examination. Although 89% had been living in the U.S.A. for more than 1 year, intestinal parasites were found in 37 (18%) patients and pathogenic parasites in 23 (11%). Among these 37 patients with intestinal parasites, seven (19%) had multiple parasites. Seven pathogenic and four nonpathogenic species were identified. Hookworm was most prevalent (4.5%), followed by Strongyloides stercoralis (2.5%) and Clonorchis sinensis (2%). Cambodians had the highest prevalence (11%) and Vietnamese and highland Laotians the lowest (0%). Intestinal parasitosis was not associated with gender or duration of residence in the U.S.A. Individual symptoms had a low positive predictive value for the presence of pathogenic parasites. This suggests that even years after immigration a substantial number of Southeast Asian refugees may benefit from screening and treatment for intestinal parasites.

Adult↗
PubMed1995

[Molecular study of 6 episodes of nosocomial infections produced by methicillin resistant Staphylococcus aureus].

A critical step in any epidemiologic research concerning nosocomial infections is the precise identification of the responsible pathogen. The present work utilized a molecular approach -plasmids identification, restriction length polymorphism DNA analysis, and random amplified polymorphic DNA- for the characterization of 6 nosocomial outbreaks due to 52 strains of methicillin-resistant Staphylococcus aureus (MRSA). In these episodes, the clinic-epidemiologic and phenotypic analysis (antibiotype) pointed to a nosocomial infection. Through molecular analysis it was possible to establish, in a very precise way, clonality due to MRSA strains in 2 of the studied outbreaks; the same type of analysis allowed to eliminate a MRSA clonal origin in the remainder 4 episodes. The antibiogram was not an useful analytic tool due to its poor discriminatory power. Also, through a PCR procedure, it was possible to identify the presence of the gen mecA in every of the 52 MRSA strains studied.

Base Sequence↗
PubMed1994

Evidence that BCL-2 represses apoptosis by regulating endoplasmic reticulum-associated Ca2+ fluxes.

BCL-2 is a 26-kDa integral membrane protein that represses apoptosis by an unknown mechanism. Recent findings indicate that Ca2+ release from the endoplasmic reticulum (ER) mediates apoptosis in mouse lymphoma cells. In view of growing evidence that BCL-2 localizes to the ER, as well as mitochondria and the perinuclear membrane, we investigated the possibility that BCL-2 represses apoptosis by regulating Ca2+ fluxes through the ER membrane. A cDNA encoding BCL-2 was introduced into WEHI7.2 cells and two subclones, W.Hb12 and W.Hb13, which express high and low levels of BCL-2 mRNA and protein, respectively, were isolated. WEHI7.2 cells underwent apoptosis in response to treatment with the glucocorticoid hormone dexamethasone, whereas W.Hb12 and W.Hb13 cells were protected from apoptosis, revealing a direct relationship between the level of BCL-2 expression and the degree of protection. Significantly, BCL-2 also blocked induction of apoptosis by thapsigargin (TG), a highly specific inhibitor of the ER-associated Ca2+ pump. TG completely inhibited ER Ca2+ pumping in both WEHI7.2 and W.Hb12 cells, but the release of Ca2+ into the cytosol after inhibition of ER Ca2+ pumping was significantly less in W.Hb12 cells than in WEHI7.2 cells, indicating that BCL-2 reduces Ca2+ efflux through the ER membrane. By reducing ER Ca2+ efflux, BCL-2 interfered with a signal for "capacitative" entry of extracellular Ca2+, preventing a sustained increase of cytosolic Ca2+ in TG-treated cells. These findings suggest that BCL-2 either directly or indirectly regulates the flux of Ca2+ across the ER membrane, thereby abrogating Ca2+ signaling of apoptosis.

Apoptosis↗
PubMed1993

Relationship between defective mouse mammary tumor virus envelope glycoprotein synthesis and GRP78 synthesis in glucocorticoid-treated mouse lymphoma cells. Evidence for translational control of GRP78 synthesis.

We have found that synthesis of the 78-kDa glucose-regulated protein, GRP78, was increased following glucocorticoid treatment of S49 and W7MG1 mouse lymphoma cell lines. These lines synthesized a 74-kDa mouse mammary tumor virus envelope glycoprotein precursor, Pr74, both constitutively and in response to glucocorticoid treatment. In these cell lines, nascent Pr74 was not processed normally but was retained within the endoplasmic reticulum where it was bound stably by GRP78. GRP78 synthesis was not increased following glucocorticoid treatment of the W7.2 mouse lymphoma cell line, which does not synthesize Pr74, suggesting that the increase in GRP78 synthesis following glucocorticoid treatment of S49 and W7MG1 cells was secondary to the glucocorticoid-induced increase in Pr74 synthesis. Consistent with this hypothesis, the glucocorticoid-induced increase in Pr74 synthesis preceded the increase in GRP78 synthesis. Also, there was a direct correlation between the level of GRP78 synthesis and the level of Pr74 synthesis among multiple subclones of the W7-ENV/N line. This line was derived from the W7.2 line by retroviral mediated transfer of a constitutively expressed sequence encoding a defective form of Pr74 that was bound stably by GRP78 within the endoplasmic reticulum. An elevation in the steady state level of GRP78 mRNA was not detected either in glucocorticoid-treated S49 cells and W7MG1 cells or in subclones of the W7-ENV/N line that have an increased level of GRP78 synthesis. Therefore, it appears that the binding of Pr74 to GRP78 induces an increase in GRP78 synthesis that is regulated at a translational level, rather than at a transcriptional level.

Animals↗
PubMed1993

Perceived risks of postoperative analgesia.

This survey aimed to determine what type of information patients want about the risks of postoperative pain management and whether this corresponded to the information that doctors and nurses wished to provide. Seventy-four patients scheduled for elective surgery, 50 nurses and 48 doctors completed a questionnaire asking about perceived risks of analgesia, level of acceptable risk and information that should be provided to patients. Compared to doctors and nurses, patients underestimated the risks associated with postoperative pain relief, except for the risk of drug addiction, which they rated higher. Ninety-one per cent of patients wanted information about the side effects of analgesia. The preferred means of obtaining this information was by discussion with their surgeon or anaesthetist. Doctors were willing to accept a greater risk of minor side effects to achieve excellent pain relief than were patients. In contrast, patients were willing to accept a greater risk of serious side effects. The results obtained in this survey will facilitate the preparation of guidelines for obtaining informed consent from patients to receive postoperative analgesia.

Adult↗
PubMed1993

Periodic variations in transcranial Doppler mean velocities.

Although serial transcranial Doppler measurements of blood flow velocity are of considerable clinical utility, their use assumes that the velocity signals are stable and unchanging during short time periods. Contrary to this assumption, the authors found significant variations in mean velocity signals in both normal subjects and patients, which may confound the interpretation of serial studies. Signals were continuously obtained for 5 to 10 minutes from the middle cerebral artery of 11 normal subjects and 18 patients (22 studies) with a variety of neurosurgical disorders. The average difference between the peak and the trough in the waves observed in the normal population was 11 +/- 4% (standard error of mean), and 5 of the 11 had at least one wave with a difference of more than 20%. The average difference between the peak and trough signals in the neurosurgical population was 14 +/- 13% (SEM) and 13 of the 22 studies showed at least one wave with a difference of more than 20%. These variations were consistently seen and may be related to similar variations in blood pressure or intracranial pressure waves. Whatever the origin, these variations should be recognized during the interpretation of transcranial Doppler signal in clinical practice.

Adult↗
PubMed1993

Rapid stimulation of Ins (1,4,5)P3 production in rat aorta by NE: correlation with contractile state.

Rapid stimulation of Ins(1,4,5)P3 production in rat aorta by NE: correlation with contractile state. Am. J. Physiol. 264 (Heart Circ. Physiol. 33): H126-H132, 1993.--The isomeric composition of inositol phosphates generated in response to norepinephrine (NE) stimulation and the relationship of inositol phosphate production to release of intracellular Ca2+ as measured by contraction were characterized in rat aorta prelabeled with [3H]inositol. NE stimulated a rapid and transient increase in labeled D-myo-inositol 1,4,5-trisphosphate [Ins-(1,4,5)P3] levels. A maximal increase in labeled Ins(1,4,5)P3 occurred within 15 s of stimulation followed by a decline to control levels at 5 min. D-Myo-inositol 1,3,4-trisphosphate [Ins-(1,3,4)P3] and D-myo-inositol 1-monophosphate [Ins(1)P] levels also increased rapidly in response to NE. In contrast to the transient production of Ins(1,4,5)P3, Ins(1,3,4)P3 and Ins(1)P production was maintained in the presence of NE. Half-maximal stimulation of Ins(1,4,5)P3 production and Ca2+ release occurred at 0.3 microM NE, and maximal effects were obtained with 10 microM NE. The concentration-response curve and time course for production of Ins(1,4,5)P3 correlated with the neurotransmitter-induced Ca2+ release from intracellular stores, indicating that the level of Ins(1,4,5)P3 regulated the Ca(2+)-release mechanism. In the continued presence of NE, the intracellular pools did not completely refill with Ca2+ despite the return of Ins-(1,4,5)P3 levels to basal at 5 min. These results demonstrate that NE stimulates a rapid increase in Ins(1,4,5)P3 that correlates with contraction in Ca(2+)-free buffer. The reuptake of Ca2+ into intracellular stores is regulated by a mechanism that may not involve Ins(1,4,5)P3.

Animals↗
PubMed1993

Breathlessness during acute bronchoconstriction in asthma. Pathophysiologic mechanisms.

The purpose of this study was to examine potential contributing factors to breathlessness during bronchoconstriction, in particular, to evaluate the role of lung hyperinflation. We also wished to elucidate qualitative aspects of the unpleasant sensory experience and to identify factors that contribute to intersubject variability in subjective and objective assessments of airflow obstruction. We studied sensory-mechanical interrelationships during and after induced bronchoconstriction in 21 subjects with mild stable asthma. Breathlessness (Borg scale), spirometry, and inspiratory capacity (IC) were measured after each dose during methacholine bronchoprovocation to a maximal change (delta) in FEV1 of 50%. Breathing pattern, specific airway resistance (SRaw), plethysmographic thoracic gas volume, and maximal inspiratory mouth pressure (MIP) were recorded at baseline, at maximal response, and at full symptom recovery. End-expiratory lung volume (EELV) was derived from IC. Borg increased from 0.4 +/- 0.1 (very, very slight) at baseline to 5.0 +/- 0.5 (severe) at maximal bronchoconstriction (mean +/- SEM, p < 0.001). FEV1 fell significantly (p < 0.001) to 48% predicted at maximal response. Of the 21 subjects, 19 reported increased inspiratory rather than expiratory difficulty and predominantly described sensations of reduced inspiratory capacity and unrewarded inspiratory effort. Stepwise multiple regression analysis using delta Borg (outcome variable) versus changes in spirometry, SRaw, IC, and breathing pattern components, selected delta IC as the principal contributing factor: delta Borg = 0.09 (delta IC, %fall); n = 193, r = 0.86, p < 0.001. delta IC continued to contribute significantly (p < 0.001) to the variance in Borg ratings after accounting for delta FEV1, and it was the strongest predictor of symptom recovery (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Effect of glucocorticosteroid treatment on intracellular calcium homeostasis in mouse lymphoma cells.

There is growing evidence for the involvement of Ca2+ in the programmed cell death (apoptosis) of lymphocytes, but the nature of glucocorticoid-induced Ca2+ fluxes and their role in the cell death pathway are poorly understood. In the study reported here, we assessed the effect of glucocorticoid treatment on intracellular Ca2+ homeostasis in W7MG1 mouse lymphoma cells. Levels of cytosolic Ca2+ were measured using the intracellular Ca2+ indicator fura2 AM, and total cellular Ca2+ was measured by atomic absorbance spectroscopy. The level of Ca2+ within internal stores, including the endoplasmic reticulum (ER), was estimated by measuring the increase in cytosolic Ca2+ induced by either ionomycin, an ionophore that mobilizes Ca2+ from a variety of internal stores, and by thapsigargin, a specific inhibitor of the ER-associated Ca(2+)-ATPase that mobilizes Ca2+ from the ER. Glucocorticoid treatment induced a significant decrease in ionomycin- and thapsigargin-mobilizable Ca2+ stores that was accompanied by an initial decrease in total cellular Ca2+, followed by a modest increase in both total cellular Ca2+ and cytosolic Ca2+. The glucocorticoid-induced depletion of internal Ca2+ stores was receptor mediated and occurred after a delay corresponding to the time required for glucocorticoid receptor complexes to regulate gene transcription. Mobilization of ER-associated Ca2+ stores by thapsigargin treatment induced DNA fragmentation and cell death similar to that observed after glucocorticoid treatment. These findings suggest that a mobilization of Ca2+ from internal stores may be a critical step in the apoptotic pathway of mouse lymphoma cells.

Animals↗