Search PubMed⌕ Search

Biomedical subjects

M McLean

Publications and source records attributed to M McLean.

At least 37 records · Page 2Linked to original sources
PubMed2000

Drinking water quality and health-care utilization for gastrointestinal illness in greater Vancouver.

The risk of microbial disease associated with drinking water is presently a priority concern among North American water jurisdictions. Numerous past outbreaks, together with recent studies suggesting that drinking water may be a substantial contributor to endemic (non-outbreak related) gastroenteritis, demonstrate the vulnerability of many North American cities to waterborne diseases and have fuelled ongoing debates in Canada and the United States concerning the need for stricter water quality guidelines, changes in watershed management policies, and the need for additional water treatment. The Greater Vancouver Regional District (GVRD) water supply system serves approximately two million consumers from a system consisting of three unfiltered surface water supplies (Figure 1). Although GVRD policies reduce the potential for fecal contamination of the source water supplies by humans and domestic animals, the GVRD watersheds support many wildlife species that can potentially shed organisms pathogenic to humans. Because GVRD's water treatment strategy relies principally on watershed protection and chlorination*, and these two strategies together do not eliminate all risk of waterborne disease transmission, it is possible that some disease-causing organisms reach the consumer.

Adolescent↗
PubMed2000

The human breast carcinoma cell line HBL-100 acquires exogenous cholesterol from high-density lipoprotein via CLA-1 (CD-36 and LIMPII analogous 1)-mediated selective cholesteryl ester uptake.

Aberrant cell proliferation is one of the hallmarks of carcinogenesis, and cholesterol is thought to play an important role during cell proliferation and cancer progression. In the present study we examined the pathways that could contribute to enhanced proliferation rates of HBL-100 cells in the presence of apolipoprotein E-depleted high-density lipoprotein subclass 3 (HDL(3)). When HBL-100 cells were cultivated in the presence of HDL(3) (up to 200 microg/ml HDL(3) protein), the growth rates and cellular cholesterol content were directly related to the concentrations of HDL(3) in the culture medium. In principle, two pathways can contribute to cholesterol/cholesteryl ester (CE) uptake from HDL(3), (i) holoparticle- and (ii) scavenger-receptor BI (SR-BI)-mediated selective uptake of HDL(3)-associated CEs. Northern- and Western-blot analyses revealed the expression of CLA-1 (CD-36 and LIMPII analogous 1), the human homologue of the rodent HDL receptor SR-BI. In line with CLA-1 expression, selective uptake of HDL(3)-CEs exceeded HDL(3)-holoparticle uptake between 12- and 58-fold. Competition experiments demonstrated that CLA-1 ligands (oxidized HDL, oxidized and acetylated low-density lipoprotein and phosphatidylserine) inhibited selective HDL(3)-CE uptake. In line with the ligand-binding specificity of CLA-1, phosphatidylcholine did not compete for selective HDL(3)-CE uptake. Selective uptake was regulated by the availability of exogenous cholesterol and PMA, but not by adrenocorticotropic hormone. HPLC analysis revealed that a substantial part of HDL(3)-CE, which was taken up selectively, was subjected to intracellular hydrolysis. A potential candidate facilitating extralysosomal hydrolysis of HDL(3)-CE is hormone-sensitive lipase, an enzyme which was identified in HBL-100 cells by Western blots. Our findings demonstrate that HBL-100 cells are able to acquire HDL-CEs via selective uptake. Subsequent partial hydrolysis by hormone-sensitive lipase could provide 'free' cholesterol that is available for the synthesis of cellular membranes during proliferation of cancer cells.

Biological Transport↗
PubMed2000

Urethral carcinoma in women: results of treatment with primary radiotherapy.

BACKGROUND AND PURPOSE: Urethral carcinoma in women is uncommon. This study was undertaken to evaluate the role of radiotherapy in the treatment of these tumors. MATERIALS AND METHODS: The hospital records of 34 women with primary urethral carcinoma were retrospectively reviewed. There were 15 squamous cell carcinomas, 13 transitional cell carcinomas, and six adenocarcinomas. The primary tumor was >4cm in size in eight patients, involved the proximal urethra in 19 and extended to adjacent organs in 22. Inguinal or iliac lymphadenopathy was present in nine patients. There were eight TNM stage I/II tumors, 11 stage III tumors and 15 stage IV tumors. Radiotherapy was administered only to the primary tumor in 15 patients, and to the primary tumor and regional lymph nodes in the remaining 19 patients. Brachytherapy with or without external radiation was used to treat the primary tumor in 20 patients. RESULTS: Tumor recurred in 21 patients. The 7-year actuarial overall and cause-specific survivals were 41 and 45%, respectively. Large primary tumor bulk and treatment with external beam radiation alone (no brachytherapy) were independent adverse prognostic factors for local tumor recurrence. Brachytherapy reduced the risk of local recurrence by a factor of 4.2. The beneficial effect of brachytherapy was most prominently seen in patients with bulky primary disease. Large tumor size was the only independent adverse predictor of overall disease recurrence and death from cancer. CONCLUSIONS: Radiotherapy is an effective treatment for carcinoma of the female urethra and preserves normal anatomy and function. Brachytherapy improves local tumor control, possibly as a result of the higher radiation dose that can safely be delivered.

Adenocarcinoma↗
PubMed2000

Introducing computer-aided instruction into a traditional histology course: student evaluation of the educational value.

Both the World Health Organisation and the World Federation for Medical Education have endorsed integration of computer technology into medical education. In line with this and for more practical reasons, second-year medical students were introduced to commercial and in-house computer-aided instruction (CAI) packages in the traditional histology course. Although CAI was well received, light microscopy was still regarded as a valuable skill in the undergraduate curriculum. Its application was viewed to be important in future medical studies, as well as in general practice. It was also perceived to be a more self-directed form of learning than CAI. Students' use of CAI packages was related to CAI meeting course objectives and the level of interactivity.

Attitude of Health Personnel↗
PubMed2000

Expression of the heme oxygenase-carbon monoxide signalling system in human placenta.

Heme oxygenase (HO) catalyses the formation of endogenous carbon monoxide and bilirubin from heme. CO, a potent vasodilator, and bilirubin, an antioxidant may have local actions in the fetal-placental vasculature of the placenta. We sought evidence of expression of the two known isoforms of HO in normal human term placenta using reverse transcription polymerase chain reaction (RT-PCR), western blotting and immunohistochemistry. RT-PCR demonstrated the presence of messenger ribonucleic acid for HO-1 and HO-2. Immunoreactive proteins of appropriate size for each HO enzyme were identified in placental cell membrane preparations. Immunohistochemistry showed a wide distribution of HO immunoreactivity, including the syncytiotrophoblast layer of placental villi, the endothelium and smooth muscle cells of umbilical-placental blood vessels, and in all layers of the fetal membranes. These data demonstrate the expression of the two known isoforms of HO in human placenta and suggest that endogenous CO and bilirubin may have important roles in the control of placental vascular function.

Carbon Monoxide↗
PubMed1999

Predicting risk of preterm delivery by second-trimester measurement of maternal plasma corticotropin-releasing hormone and alpha-fetoprotein concentrations.

OBJECTIVE: Many women who have preterm labor have abnormally high plasma concentrations of the placental peptide corticotropin-releasing hormone and the fetal product alpha-fetoprotein in early pregnancy. This study was designed to evaluate the ability of these biochemical tests and a clinical risk factor score to prospectively discriminate pregnancies at high risk for preterm delivery. STUDY DESIGN: Eight hundred sixty women were studied prospectively from the early second trimester until delivery. A risk factor score for preterm delivery was calculated from the clinical history and maternal plasma corticotropin-releasing hormone and alpha-fetoprotein concentrations were measured by radioimmunoassay between 17 and 30 weeks' gestation. The risk factor score, corticotropin-releasing hormone concentration, and alpha-fetoprotein concentration for each woman were expressed as individual odds or likelihood ratios for preterm delivery and as a combined risk estimate derived from the 3 tests. RESULTS: Sixty women had preterm deliveries (n = 37 spontaneous labor, n = 23 planned deliveries), and these women had significantly higher concentrations of corticotropin-releasing hormone (median 1.92 multiples of the median) and alpha-fetoprotein (median 1.32 multiples of the median) than did women with term deliveries (median 1.00 multiples of the median, P <.001 for both tests), with these abnormalities being evident from early in the second trimester. The risk factor score was >/=10 in 28% of women with preterm delivery and 7% of women with term delivery. The combination of all 3 markers resulted in a higher detection rate and a higher positive predictive value than the risk factor score, corticotropin-releasing hormone concentration, or alpha-fetoprotein concentration alone, correctly discriminating 37% of women who would have preterm deliveries with a false-positive rate of 5%. The positive predictive value was also 37% (odds of being affected given a positive result were 1:1.7). CONCLUSIONS: The combination of measurement of maternal plasma corticotropin-releasing hormone and alpha-fetoprotein concentrations in the second trimester with risk factor scoring provides a more accurate indicator of the risk of preterm delivery than does risk factor scoring alone. This method of risk assessment may therefore be of use in targeting prevention strategies.

Adolescent↗
PubMed1999

Corticotropin-releasing Hormone in Human Pregnancy and Parturition.

The role of corticotropin-releasing hormone (CRH) in the regulation of pituitary adrenocorticotropin secretion and the stress response is well established. However, in recent years this peptide has been found to serve a number of functions outside the classic neuroendocrine domain. During pregnancy, CRH derived from the placenta is thought to play a crucial role in the regulation of foetal maturation and the timing of delivery, and CRH has also been implicated in the control of foetal-placental bloodflow. Abnormalities of the placental CRH system might be involved in the pathogenesis of preterm labour, foetal growth retardation and pre-eclampsia, which are the three leading causes of perinatal morbidity and mortality in developed countries.

Journal Article↗
PubMed1999

Effects of propranolol and L-NAME on beta-adrenoceptor-mediated relaxation in rat carotid artery.

1. The properties of beta-adrenoceptors mediating vascular relaxation in rat isolated carotid artery were investigated. Ring segments of arteries were preconstricted with the thromboxane A2 receptor agonist U-46619 and relaxation to beta-adrenoceptor agonists determined. 2. Isoprenaline produced a concentration-dependent relaxation of U-44619-constricted arteries. The concentration-response curve (CRC) to isoprenaline was shifted to the right by propranolol (1 microM) although the shift was less (105 fold; pA2, 8.02) than would be expected for an effect of isoprenaline at classical beta-adrenoceptors (300-1000 fold; pA2, 8.5-9). L-NAME (100 microM) significantly reduced responses to isoprenaline, lowering the slope of the CRC and reducing the maximum response. 3. The selective beta3-adrenoceptor agonists, BRL 37344 and ZD2079, also produced concentration-dependent relaxation of the arteries. L-NAME (100 microM) shifted the BRL 37344 CRC to the right 15 fold with no reduction in the slope or maximum response. L-NAME (100 microM) had no significant effect on the ZD2079 CRC. 4. In conclusion, relaxation to isoprenaline in rat carotid artery is inhibited by propranolol in a manner suggesting a mixed population of classical (beta1-/beta2-) and atypical (beta3-) adrenoceptors. The presence of beta3-adrenoceptors was confirmed by the relaxant effects of the selective beta3-adrenoceptor agonists BRL 37344 and ZD2079. L-NAME attenuated responses to both isoprenaline and the beta3-adrenoceptor agonist BRL 37344, suggesting a role for endothelial release of nitric oxide in beta-adrenoceptor mediated relaxation. However, the relaxant effect of BRL 37344 was attenuated by L-NAME to a lesser extent than that of isoprenaline. In addition, L-NAME had no effect on relaxation induced by ZD2079. These results suggest that there may be a differential contribution of endothelium to classical beta-and beta3-adrenoceptor-mediated effects, with endothelium contributing less to beta3-adrenoceptor-mediated relaxation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

Expression and functional analysis of endothelial nitric oxide synthase (eNOS) in human placenta.

We have investigated the expression and localization of endothelium-derived nitric oxide synthase (eNOS) and the effect of eNOS on placental human chorionic gonadotrophin (HCG) release. eNOS mRNA was found to be expressed in all tissues, with its expression significantly (P<0.05) increased across gestation. Compared to normal term gestation, placentae from term pregnancies with fetal retardation, or maternal diabetes, but not with maternal hypertension, displayed significantly more (P<0.05) eNOS mRNA. By immunocytochemistry, we found staining for eNOS in both the cyto- and syncytiotrophoblasts of first trimester and a loss of cytotrophoblast eNOS staining in term placentae, while syncytiotrophoblasts at term were strongly eNOS positive. Additional staining was found in endothelium surrounding the vascular tree. HCG was found to colocalize with eNOS in trophoblasts, but not in endothelia. When placental explants were perifused, exposure to the NOS substrate, the NO donor, I-arginine and trinitroglycerol evoked a prompt, albeit transient, increase of HCG release. The NOS inhibitor delayed, but did not block arginine-induced HCG release. Thus, eNOS is expressed in the human placenta at increasing levels during gestation with further increases during some pathological conditions. A role for NO in the acute endocrine modulation of the placenta is suggested by the colocalization of eNOS with HCG in human trophoblasts and the prompt secretion of HCG in response to agents which increase NO concentrations.

Cells, Cultured↗
PubMed1999

Elevated mid-trimester maternal corticotrophin-releasing hormone levels in pregnancies that delivered before 34 weeks.

OBJECTIVE: To test whether maternal corticotrophin-releasing hormone levels are elevated in the mid- trimester for those women who subsequently had spontaneous preterm delivery and to assess the clinical utility of the measurement in the prediction of preterm delivery. DESIGN: A prospective observational study. SETTING: Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Hong Kong. POPULATION: 1047 low risk pregnant women recruited at 15-20 weeks of gestation. METHODS: Venous samples were assayed for levels of corticotrophin-releasing hormone. The investigators responsible for the laboratory assay were blinded to the obstetric outcome. MAIN OUTCOME MEASURES: Incidence of preterm, term and post-term pregnancies. RESULTS: Those who were delivered spontaneously at a preterm gestational age (before 34 weeks) had significantly higher corticotrophin-releasing hormone levels in the mid-trimester, compared with those who were delivered at term or post-term. There was a trend towards lower corticotrophin-releasing hormone levels with more advanced gestational age at delivery. When the measurement of corticotrophin- releasing hormone was used to predict delivery before 34 weeks, the best cut off was 1.9 MoM, which produced a sensitivity of 72.7% and specificity of 78.4%. This translated to a positive predictive value of 3.6%, negative predictive value of 99.6% and relative risk of 9.4 when the background prevalence of spontaneous preterm delivery before 34 weeks was 1.1%. The likelihood ratio was 3.4. CONCLUSIONS: Mid-trimester maternal corticotrophin-releasing hormone levels are elevated in pregnancies destined to deliver preterm before 34 weeks. When used alone in a low risk population, the measurement has a low predictive power for preterm delivery. However, the likelihood ratio of 3 4 implies that in high risk populations the test may be considerably more valuable.

Adult↗
PubMed1999

Organization of inhibitory frequency receptive fields in cat primary auditory cortex.

Based on properties of excitatory frequency (spectral) receptive fields (esRFs), previous studies have indicated that cat primary auditory cortex (A1) is composed of functionally distinct dorsal and ventral subdivisions. Dorsal A1 (A1d) has been suggested to be involved in analyzing complex spectral patterns, whereas ventral A1 (A1v) appears better suited for analyzing narrowband sounds. However, these studies were based on single-tone stimuli and did not consider how neuronal responses to tones are modulated when the tones are part of a more complex acoustic environment. In the visual and peripheral auditory systems, stimulus components outside of the esRF can exert strong modulatory effects on responses. We investigated the organization of inhibitory frequency regions outside of the pure-tone esRF in single neurons in cat A1. We found a high incidence of inhibitory response areas (in 95% of sampled neurons) and a wide variety in the structure of inhibitory bands ranging from a single band to more than four distinct inhibitory regions. Unlike the auditory nerve where most fibers possess two surrounding "lateral" suppression bands, only 38% of A1 cells had this simple structure. The word lateral is defined in this sense to be inhibition or suppression that extends beyond the low- and high-frequency borders of the esRF. Regional differences in the distribution of inhibitory RF structure across A1 were evident. In A1d, only 16% of the cells had simple two-banded lateral RF organization, whereas 50% of A1v cells had this organization. This nonhomogeneous topographic distribution of inhibitory properties is consistent with the hypothesis that A1 is composed of at least two functionally distinct subdivisions that may be part of different auditory cortical processing streams.

Acoustic Stimulation↗
PubMed1999

Epidemic and endemic seroprevalence of antibodies to Cryptosporidium and Giardia in residents of three communities with different drinking water supplies.

This study was carried out to compare cryptosporidiosis and giardiasis seroprevalence rates in residents of three communities. Community (Com 1) uses drinking water from deep wells, community 2 (Com 2) uses surface water from a protected watershed, and community 3 (Com 3) uses surface water frequently containing Cryptosporidium oocysts and Giardia cysts. Unfiltered drinking water from each community was collected at the tap and tested for Cryptosporidium oocysts and Giardia cysts during the 12 months in which sera were collected for testing. No oocysts or cysts were detected in the water from the Com 1 deep wells; oocysts and cysts were detected intermittently in the drinking water from the other two communities. A waterborne outbreak of cryptosporidiosis occurred in a municipality adjacent to Com 3 six months into this 12-month study. Sera from residents of each of the communities were collected proportionately by month and by population size. Coded sera were tested for IgG to Cryptosporidium using a previously developed Western blotting method. The presence or absence of bands at 15-17 kD and/or 27 kD was recorded for the 1,944 sera tested. Definite bands at 15-17 kD and/or 27 kD were detected in 981 (50.5%) of the sera. A total of 33.2% of sera from Com 1 (community using deep wells) were positive using the same criteria compared with 53.5% (Com 2) and 52.5% (Com 3) of sera from the two communities using surface drinking water. Both bands (15-17 kD plus 27 kD) were detected in 582 sera (29.9%) from the three communities: 14.1% of sera from Com 1 compared with 32.7% from Com 2 and 31.5% from Com 3. These findings are consistent with a lower risk of exposure to Cryptosporidium from drinking water obtained from deep well sources. However, analysis of results by calendar quarter showed a significant (P < 0.001) increase in the number of Com 3 positive sera (compared with Com 1) following the waterborne outbreak. Without this outbreak-related observation, a significant overall difference in seropositivity would not have been seen. We also observed that in sera from the community affected by the outbreak, the presence on immunoblots of both Cryptosporidium bands appeared to be the best indicator of recent infection. Seroprevalence rates using an ELISA to detect IgG to Giardia were estimated using the same sera. Overall 30.3% (590 of 1,944) of sera were positive by the ELISA. A total of 19.1% of sera from Com 1, 34.7% from Com 2 and 16.0% from Com 3 were seropositive. Rates for both Com 3 and Com 1 did not change significantly over time. In Com 2, rates decreased significantly (P < 0.001) during the last half of the study period (third and fourth calendar quarters). The reasons for the decrease in seroprevalence in Com 2 sera are presently not known. These studies show intriguing associations between seroprevalence, outbreak-related laboratory serologic data, and patterns of parasite contamination of drinking water. Further studies are required to validate the serologic approach to risk assessment of waterborne parasitic infections at a community level.

Animals↗
PubMed1998

T1/T2 glottic cancer managed by external beam radiotherapy: the influence of pretreatment hemoglobin on local control.

PURPOSE: Pretreatment hemoglobin (Hb) level has been reported to be an important prognostic factor for local control and survival in various malignancies. However, in many settings, the adverse effect of a low Hb may be related to more advanced disease. The purpose of this analysis was to assess the influence of pretreatment Hb on local control in a large series of patients with a localized cancer (T1/T2 glottic cancer, AJCC 1992) treated in a standard fashion. MATERIALS AND METHODS: Between January 1981 and December 1989, 735 patients (median age 63; 657 males, 78 females) with T1/T2 glottic cancer were treated with radiation therapy (RT). The standard RT prescription was 50 Gy in 20 fractions over 4 weeks (97% of patients). Factors studied for prognostic importance for local failure included pretreatment Hb, age, sex, T category, anterior commissure involvement, subglottic extension, and tumor bulk (presence of visible tumor vs. subclinical disease). RESULTS: With a median follow-up of 6.8 years (range 0.2-14.3), 131 patients have locally relapsed for an actuarial 5-year relapse-free rate of 81.7%. The 5-year actuarial survival was 75.8%. The mean pretreatment hemoglobin level was 14.8 g/dl and was similar in all prognostic categories. On multivariate analysis, using the Cox proportional hazards model, pretreatment Hb predicted for local failure after RT. The hazard ratio (HR) for relapse was calculated for various Hb levels. For example, the HR for a Hb of 12 g/dl vs. a Hb of 15 g/dl was 1.8 (95% confidence interval 1.2-2.5). Previously established factors, including gender, T category, subglottic extension, as well as tumor bulk, were also prognostically important for local control. CONCLUSIONS: This analysis, in a large number of similarly treated patients, indicates that pretreatment Hb is an independent prognostic factor for local control in patients with T1/T2 carcinoma of the glottis treated with RT. The underlying biology of this observation needs to be explored, and using this information, it may be possible to develop strategies to improve treatment outcome.

Carcinoma, Squamous Cell↗
PubMed1998

Treatment of locally recurrent rectal carcinoma--results and prognostic factors.

PURPOSE: To assess the local control and survival in patients who received pelvic irradiation for locally recurrent rectal carcinoma. METHODS AND MATERIALS: The records of 519 patients with locally recurrent rectal carcinoma treated principally with external-beam radiation therapy between 1975 to 1985 at a single institute were retrospectively reviewed. These included 326 patients who relapsed locally following previous abdominoperineal resection, 151 after previous low anterior resection, and 42 after previous local excision or electrocoagulation for the primary. No patients had received adjuvant radiation therapy or chemotherapy for the primary disease. Concurrent extrapelvic distant metastases were found in 164 (32%) patients at local recurrence and, in the remaining 355, the relapse was confined to the pelvis. There were 290 men and 229 women whose age ranged from 23 to 91 years (median = 65). Median time from initial surgery to radiation therapy for local recurrence was 18 months (3-138 months). Radiation therapy was given with varying dose-fractionation schedules, total doses ranging from 4.4 to 65.0 Gy (median = 30 Gy) over 1 to 92 days (median = 22 days). For 214 patients who received a total dose > or = 35 Gy, radiation therapy was given in 1.8 to 2.5 Gy daily fractions. RESULTS: The median survival was 14 months and the median time to local disease progression was 5 months from date of pelvic irradiation. The 5-year survival was 5%, and the pelvic disease progression-free rate was 7%. Twelve patients remained alive and free of disease at 5 years after pelvic irradiation. Upon multivariate analysis, overall survival was positively correlated with ECOG performance status (p = 0.0001), absence of extrapelvic metastases (p = 0.0001), long intervals from initial surgery to radiation therapy for local recurrence (p = 0.0001), total radiation dose (p = 0.0001), and absence of obstructive uropathy (p = 0.0013). Pelvic disease progression-free rates were positively correlated with ECOG performance status (p = 0.0001), total radiation dose (p = 0.0001), and previous conservative surgery for the primary (p = 0.02). CONCLUSIONS: Survival is poor for patients who develop local recurrence following previous surgery for rectal carcinoma. Pelvic radiation therapy provides only short-term palliation, and future efforts should be directed to the use of effective adjuvant therapy for patients with rectal carcinoma who are at high risk of local recurrence.

Adult↗
PubMed1998

Corticotropin-releasing hormone: a biochemical predictor of preterm delivery in a pilot randomized trial of the treatment of preterm labor.

OBJECTIVE: We assessed the ability of maternal plasma corticotropin-releasing hormone measurements to predict preterm delivery in the setting of a pilot study comparing transdermal glyceryl trinitrate with standard beta-mimetic therapy for preterm labor and to determine the effect of these tocolytics on maternal plasma corticotropin-releasing hormone concentrations. STUDY DESIGN: Twenty-six consecutive patients with preterm labor were randomized to tocolytic treatment with transdermal glyceryl trinitrate (n=13) or intravenous albuterol (n=13). RESULTS: Plasma corticotropin-releasing hormone immunoreactivity levels were higher in women who were delivered within 7 days (41.4+/-13.5 pmol/L) than in those continuing to term (14.2+/-2.4 pmol/L, p=0.011) and were not altered by treatment. Two women in each of the treatment groups delivered within 7 days of the initiation of treatment, two women in the glyceryl trinitrate group were changed to albuterol because of persistence of contractions. Glyceryl trinitrate treatment was associated with significantly fewer maternal side effects. Neither treatment altered umbilical artery Doppler ultrasonographic findings. CONCLUSION: Transdermal glyceryl trinitrate is better tolerated than intravenous albuterol but may be no more efficacious than albuterol for the treatment of preterm labor. Biologic markers such as plasma corticotropin-releasing hormone levels may be an important method of identifying women at high risk of preterm delivery.

Administration, Cutaneous↗
PubMed1998

Magnetic resonance imaging (MRI) for localization of the prostatic apex: comparison to computed tomography (CT) and urethrography.

BACKGROUND AND PURPOSE: It is necessary to include the entire prostate in the high dose treatment volume when planning radical radiation for patients with prostate cancer. We prospectively compared magnetic resonance imaging (MRI) to computed tomography (CT) and urethrography as means of localizing the prostatic apex. MATERIALS AND METHODS: Thirty patients with clinically localized prostate cancer had a sagittal T2-weighted MRI scan and a conventional axial CT scan performed in the treatment position prior to the start of radiotherapy. Twenty of these patients had a static retrograde urethrogram performed at simulation. The position of the MRI and CT apices were localized independently by two radiation oncologists. In addition, the MRI apex was localized independently by a diagnostic radiologist. The urethrogram apex, defined as the tip of the urethral contrast cone, was easily identified and was therefore localized by only one observer. RESULTS: There was good interobserver agreement in the position of the MRI apex. Interobserver agreement was significantly better with MRI than with CT. There were no systematic differences in the position of the MRI and CT apices. However, the MRI apex was located significantly above and behind the urethrogram apex. There was poor correlation between MRI and CT and between MRI and urethrogram in the height of the apex above the ischial tuberosities. There was 83% agreement between MRI and CT and 80% agreement between MRI and urethrogram in the identification of patients with a low-lying apex. The apex, as determined by MRI, was <2 cm above the ischial tuberosities and therefore potentially under-treated in 17% of the patients. CONCLUSIONS: MRI is superior to CT and urethrography for localization of the prostatic apex. All patients undergoing radiotherapy for prostate cancer should have localization of the apex using MRI or a technique of equal precision to assure adequate dose delivery to the entire prostate and to minimize the unnecessary irradiation of normal tissues.

Adenocarcinoma↗
PubMed1998

Re-irradiation for locally recurrent nasopharyngeal carcinoma.

Since 1989, 17 patients have undergone re-irradiation for locally recurrent nasopharyngeal cancer (NPC). The dose currently administered externally is 39.6 Gy in 36 fractions (BID) followed by an intracavitary boost (15-20 Gy). Disease persisted in five out of five patients treated palliatively. Eleven of 12 patients treated with curative intent achieved local control.

Adult↗