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1.
Hong Kong Med J ; 27(6): 405-412, 2021 12.
Article in English | MEDLINE | ID: mdl-34924363

ABSTRACT

INTRODUCTION: The effect of massage for pain relief during labour has been controversial. This study investigated the efficacy of a programme combining intrapartum massage, controlled breathing, and visualisation for non-pharmacological pain relief during labour. METHODS: This randomised controlled trial was conducted in two public hospitals in Hong Kong. Participants were healthy low-risk nulliparous Chinese women ≥18 years old whose partners were available to learn massage technique. Recruitment was performed at 32 to 36 weeks of gestation; women were randomised to attend a 2-hour childbirth massage class at 36 weeks of gestation or to receive usual care. The primary outcome variable was the intrapartum use of epidural analgesia or intramuscular pethidine injection. RESULTS: In total, 233 and 246 women were randomised to the massage and control groups, respectively. The use of epidural analgesia or pethidine did not differ between the massage and control groups (12.0% vs 15.9%; P=0.226). Linear-by-linear analysis demonstrated a trend whereby fewer women used strong pharmacological pain relief in the massage group, and a greater proportion of women had analgesic-free labour (29.2% vs 21.5%; P=0.041). Cervical dilatation at the time of pethidine/epidural analgesia request was significantly greater in the massage group (3.8 ± 1.7 cm vs 2.3 ± 1.0 cm; P<0.001). CONCLUSION: The use of a massage programme appeared to modulate pain perception in labouring women, such that fewer women requested epidural analgesia and a shift was observed towards the use of weaker pain relief modalities; in particular, more women in the massage group were analgesic-free during labour.


Subject(s)
Analgesia, Obstetrical , Labor Pain , Adolescent , Female , Humans , Labor Pain/therapy , Massage , Parturition , Patient Satisfaction , Pregnancy , Pregnant Women
2.
Eat Weight Disord ; 25(5): 1303-1309, 2020 Oct.
Article in English | MEDLINE | ID: mdl-31473985

ABSTRACT

PURPOSE: Early adulthood is a high-risk time for weight gain; however, young women with obesity are difficult to recruit to weight management programs. To encourage participation and retention, it is important to understand what young women want from these programs. The purpose of the study was to explore participants' perspectives on the features of an ideal weight management program. METHODS: Semi-structured interview schedules were used to elicit information from eight focus groups [27 women; mean age of 29.1 (± 5.1) years, mean body mass index (BMI; kg/m2) of 35.8 (± 2.9)]. The focus groups were transcribed, coded and analyzed qualitatively. RESULTS: The themes that emerged were program content, format, program characteristics, program name, location and duration. A major finding from the study is that participants value a program that includes nutritional, psychological and lifestyle interventions, and includes components that are not traditionally part of weight management programs such as body acceptance, sexual health and dressing and grooming. A program name that conveys wellness and body positivity was valued. Participants highlighted the importance of individualized programs that are also tailored to the needs of young adults, and delivered by credible and approachable staff who provide accountability. Cost-effectiveness, flexibility, accessibility, time-commitment were important considerations and the use of a combination of virtual and in-person methods (including group interventions) appealed to this cohort. CONCLUSION: Knowledge of program features which resonate with young women facilitates development of innovative ways to engage and support evidence-based weight management in this vulnerable group. LEVEL OF EVIDENCE: V.


Subject(s)
Weight Reduction Programs , Adult , Body Mass Index , Female , Humans , Life Style , Obesity/therapy , Weight Gain , Young Adult
3.
Opt Express ; 26(10): 12790-12800, 2018 May 14.
Article in English | MEDLINE | ID: mdl-29801314

ABSTRACT

Mode-locked fiber laser incorporating a saturable absorber is an attractive configuration due to its stability and simple structure. In this work, we demonstrate a dual-wavelength passively mode-locked erbium-doped fiber laser employing a graphene/polymethyl-methacrylate saturable absorber. A laser resonator is developed based on dual cavity architecture with unidirectional signal oscillation, which is connected by a fiber branch sharing a common gain medium and saturable absorber. Dual wavelength mode-locked fiber lasers are observed at approximately 1530 and 1560 nm with 22.6 mW pump power threshold. Soliton pulse circulates in the laser cavity with pulse duration of 900 and 940 fs at shorter and longer wavelengths, respectively. This work presents a viable option in developing a low threshold mode-locked laser source with closely spaced dual wavelength femtosecond pulses in the C-band wavelength region.

4.
Hong Kong Med J ; 20(5): 455-9, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25307076

ABSTRACT

Tardive dystonia is an iatrogenic complication of dopamine receptor antagonist medication such as first-generation antipsychotics. It occurs in up to 2% of patients and only 10% recover after stopping medication. Deep brain stimulation for primary dystonia has proven to be effective and its application for secondary dystonias is gaining acceptance. We report our experience in treating three ethnic Chinese schizophrenia patients with severe medically refractory tardive dystonia by globus pallidus internus deep brain stimulation. Preoperatively, all required assistance with essential activities of daily living and two were bed-bound. The mean Burke-Fahn-Marsden Dystonia Rating Scale score was 61 (range, 44-80) and mean Global Dystonia Rating Scale score was 47 (range, 40-52). No procedure-related complications were encountered. By 3 months all could return to unassisted living and walk with support with a mean of 77% and 66% improvement in the Burke-Fahn-Marsden Dystonia Rating Scale and Global Dystonia Rating Scale scores, respectively. Quality-of-life assessment performed for two patients using the EuroQol-5 dimensions visual analogue scale showed a mean improvement of 86% at 3 months. On clinical follow-up, the effect was well maintained for a period of 3 to 10 years. Pallidal deep brain stimulation is a safe and highly effective form of symptomatic treatment for patients with medically refractory tardive dystonia.


Subject(s)
Globus Pallidus , Movement Disorders/therapy , Schizophrenia, Paranoid , Adult , Deep Brain Stimulation/methods , Diagnosis, Differential , Female , Humans , Male , Middle Aged , Movement Disorders/diagnosis , Movement Disorders/pathology , Psychiatric Status Rating Scales , Quality of Life , Severity of Illness Index
5.
Hong Kong Med J ; 15(2): 143-5, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19342742

ABSTRACT

Gout is a common metabolic disease but spinal gout is rare. We report a case of gouty arthritis affecting the thoracic spine in a 76-year-old male patient with a long history of tophaceous gout who presented with bilateral lower limb weakness. Magnetic resonance imaging of his thoracic spine revealed erosions in the left pedicles of T8 and T10. The initial imaging diagnosis was metastatic disease. A computed tomography-guided biopsy of the T10 lesion was performed and confirmed the diagnosis of gout. We advocate the use of computed tomography-guided fine-needle aspiration/biopsy for diagnosing spinal gout because the imaging features are non-specific, metastasis and spondylodiscitis being important mimickers.


Subject(s)
Arthritis, Gouty/diagnosis , Spinal Diseases/diagnosis , Aged , Biopsy , Diagnosis, Differential , Humans , Male , Spinal Neoplasms/diagnosis , Spinal Neoplasms/secondary , Tomography, X-Ray Computed
6.
Nutr Diet ; 76(4): 392-398, 2019 09.
Article in English | MEDLINE | ID: mdl-30575276

ABSTRACT

AIM: Recruiting young women to weight management research programs is difficult. The purpose of this study was to gain insights into the barriers and motivators that influence participation and to explore effective methods of recruitment from the perspective of young women with obesity living in both urban and regional areas. METHODS: Semi-structured interviews were used to elicit information from focus groups. The interviews were transcribed, coded and analysed qualitatively. Eight focus groups, which included a total of 27 women, were conducted. Participants had a mean age of 29.1 (±5.1) years and a mean body mass index of 35.8 (±2.9) kg/m2 . RESULTS: The barriers to participation were multifaceted and largely similar across urban and regional participants. Fear of judgement and uncertainty about the process were major psychosocial barriers. A lack of tailoring of program content was an important program-related barrier. Physical barriers such as time commitment, cost and access were discussed extensively, particularly in urban groups. The provision of incentives and the use of positive language that focusses on the benefits of the intervention were viewed positively. Physical and virtual methods of recruitment were identified as potentially effective provided they were presented in media that this group is likely to use and can access in a private location. CONCLUSIONS: The results of this study provide a greater understanding of the challenges faced by young women in relation to participation in weight management programs and some of the potential methods that could be utilised to facilitate participation.


Subject(s)
Health Knowledge, Attitudes, Practice , Health Services Accessibility/statistics & numerical data , Motivation , Obesity/therapy , Patient Selection , Weight Reduction Programs/statistics & numerical data , Adolescent , Adult , Australia , Female , Focus Groups , Humans , Interviews as Topic , Judgment , Rural Population , Uncertainty , Urban Population , Young Adult
7.
Breast ; 17(2): 132-7, 2008 Apr.
Article in English | MEDLINE | ID: mdl-17905584

ABSTRACT

Annual surveillance mammography is commonly recommended after breast conservation therapy (BCT). We retrospectively reviewed its effectiveness on 511 invasive and non-invasive breast cancers treated with BCT between 1994 and 2003. The median follow-up was 5.9 years. The 5-year actuarial ipsilateral breast tumour recurrence (IBTR) rate was 4.5% and contralateral breast cancer (CBC) rate was 2.0% (representing eight times increase in risk). IBTR of 43% and 62% CBC were first detected by surveillance mammography. The IBTR detection rates per 1000 mammograms were 5.2 for patients (n=349) with one or more IBTR risk factors (age 45, positive/close margins or histological grade 3) and 0.6 for patients (n=162) without. No survival difference was observed between different modes of IBTR detection (p=0.342). In conclusion, a risk-adapted approach of limiting ipsilateral surveillance to patients with IBTR risk is possible but its implementation will be complicated by the continued need of contralateral surveillance.


Subject(s)
Breast Neoplasms/diagnostic imaging , Breast Neoplasms/surgery , Mammography/economics , Mastectomy, Segmental , Neoplasm Recurrence, Local/diagnostic imaging , Adult , Aged , Aged, 80 and over , Cost-Benefit Analysis , Feasibility Studies , Female , Hong Kong , Humans , Middle Aged , Retrospective Studies , Risk Assessment , Risk Factors , Survival Analysis , Survival Rate , Treatment Outcome
8.
Hong Kong Med J ; 14(4): 324-6, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18685169

ABSTRACT

Cervical spondylolysis is an uncommon entity. It is important to recognise its characteristic radiological features and differentiate it from acute cervical fractures or dislocations in patients with neck injuries. We report the relevant clinical and radiological findings seen in a young Chinese woman managed in our hospital after a neck injury who was ultimately diagnosed with bilateral cervical spondylolysis with spondylolisthesis at C6.


Subject(s)
Cervical Vertebrae/diagnostic imaging , Neck Injuries/diagnostic imaging , Spondylolisthesis/diagnostic imaging , Spondylosis/diagnostic imaging , Tomography, X-Ray Computed , Accidents, Traffic , Asian People , Female , Follow-Up Studies , Humans , Incidental Findings , Injury Severity Score , Neck Injuries/therapy , Risk Assessment , Spondylolisthesis/diagnosis , Spondylolisthesis/therapy , Spondylosis/diagnosis , Spondylosis/therapy , Young Adult
9.
J Inherit Metab Dis ; 30(6): 981, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17922216

ABSTRACT

Ornithine transcarbamylase deficiency is the commonest urea cycle disorder which is transmitted in X-linked inheritance. It is mainly characterized in males by acute encephalopathy and hyperammonaemia with fatal outcomes in both classical neonatal and late-onset types. We report a 3-year-old healthy Hong Kong Chinese boy who presented with acute encephalopathy and coma after three days of gastroenteritis. He had no focal neurological deficit and brain CT imaging was normal. His plasma ammonia (54 micromol/L) and glutamine (747 micromol/L) concentrations were normal. The only biochemical abnormalities detected were marked orotic aciduria (700 micromol/mmol creatinine) and elevated urinary uracil. He regained consciousness spontaneously after three days under intensive care with parenteral fluid therapy. He recovered completely without any neurological deficits. Five months after discharge, urinary uracil concentration remained elevated despite normalized orotic acid concentration. Finally, ornithine transcarbamylase deficiency was diagnosed by DNA analysis. A missense mutation of arginine-to-glutamine substitution on amino acid 277 (p.R277Q) was revealed to be a late-onset mutant. Our case strengthens the argument that in any child with coma or acute encephalopathy of undetermined cause, genetic analysis of the OTC gene and the measurement of urinary uracil concentration remain the most reliable indicators of late-onset OTCD during acute and even quiescent phases. Existing neonatal screening programmes for inheritable metabolic disorders fail to detect late-onset variants. Therefore, a high clinical suspicion is a key to correct and timely diagnosis, especially in those patients with atypical presentations.


Subject(s)
Brain Diseases, Metabolic/diagnosis , Brain Diseases, Metabolic/therapy , Ornithine Carbamoyltransferase Deficiency Disease/complications , Ornithine Carbamoyltransferase Deficiency Disease/therapy , Ammonia/metabolism , Child, Preschool , DNA Mutational Analysis , Glutamine/metabolism , Humans , Male , Mutation, Missense , Ornithine Carbamoyltransferase/metabolism , Treatment Outcome
10.
Hong Kong Med J ; 12(3): 235-8, 2006 Jun.
Article in English | MEDLINE | ID: mdl-16760556

ABSTRACT

A female patient with end-stage renal failure, who was maintained on haemodialysis via multiple central dialysis catheters, developed chronic occlusion of the left brachiocephalic vein. Subsequently, the right jugular dual lumen PermCath became dysfunctional because of marked superior vena cava stenosis. Angioplasty of the superior vena cava stenosis was performed but failed to restore adequate catheter function. The patient was referred for possible salvage of her central venous access and re-insertion of a new PermCath. During surgery, the right jugular PermCath was removed, the superior vena cava was stented to establish venous patency, and a new PermCath was re-inserted via the existing right jugular puncture site. The technique helps reduce cost and time, and avoids another jugular puncture. In addition, this procedure saves a central venous access which is important in patients on long-term haemodialysis.


Subject(s)
Angioplasty, Balloon , Catheters, Indwelling/adverse effects , Kidney Failure, Chronic/therapy , Renal Dialysis/instrumentation , Superior Vena Cava Syndrome/therapy , Aged , Angiography, Digital Subtraction , Catheterization, Central Venous , Constriction, Pathologic/diagnostic imaging , Device Removal , Equipment Failure , Female , Humans , Jugular Veins/diagnostic imaging , Stents , Superior Vena Cava Syndrome/diagnostic imaging
11.
Arch Intern Med ; 146(6): 1214-5, 1986 Jun.
Article in English | MEDLINE | ID: mdl-3718109

ABSTRACT

A 17-year-old schizophrenic developed severe hypernatremia during a period of psychosis. The thirst-deficient abnormality that caused this hypernatremia resolved when his psychosis improved. The primary disorders causing a thirst deficiency leading to hypernatremia fall into three categories: lesions of the central nervous system, mineralocorticoid excess, and drug side effects. None of these disorders was found in our patient. We conclude that psychosis can severely impair the thirst mechanism directly.


Subject(s)
Hypernatremia/etiology , Schizophrenia/complications , Adolescent , Dehydration/diagnosis , Dehydration/etiology , Dehydration/pathology , Humans , Hypernatremia/diagnosis , Hypernatremia/pathology , Male , Osmolar Concentration , Schizophrenia/diagnosis , Schizophrenia/pathology , Thirst/physiology , Vasopressins/blood
12.
Int J Radiat Oncol Biol Phys ; 50(3): 759-63, 2001 Jul 01.
Article in English | MEDLINE | ID: mdl-11395245

ABSTRACT

PURPOSE: To evaluate the long-term brain metabolite changes on (1)H-MRS in acute lymphoblastic leukemia (ALL) patients who had intrathecal methotrexate (ITMTX) and cranial irradiation (CRT) for central nervous system (CNS) prophylaxis against CNS relapse. METHODS AND MATERIALS: Thirty-seven ALL patients (12 females, 25 males) with history of ITMTX and CRT for CNS prophylaxis were studied. Age ranges at the time of diagnosis and at magnetic resonance examination were 0.8-13 years and 12-27 years, respectively. The interval since diagnosis was 5.6-19 years. T2-weighted and gradient-recalled echo (GRE) magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ((1)H-MRS) were performed to assess brain injury. RESULTS: On MRI, 3 leukoencephalopathy (LEP) and 1 infarct were detected. Twenty-two patients had evidence of hemosiderin. On (1)H-MRS no statistically significant difference in choline (Cho)/creatine (Cr) and N-acetylaspartate (NAA)/Cr was associated with LEP. A lower Cho/Cr (p = 0.006) and NAA/Cr (p = 0.078) was observed in brains with hemosiderin. Linear-regression analysis showed no statistically significant relationship between NAA/Cr or Cho/Cr with age at diagnosis, but there was a statistically significant decreasing trend of NAA/Cr and Cho/Cr with the interval since diagnosis. CONCLUSION: Long-term brain injury in ALL survivors after CNS prophylaxis with ITMTX and CRT was reflected by decreasing NAA/Cr and Cho/Cr with the interval since diagnosis. The lower Cho/Cr associated with hemosiderin but not LEP suggested a different pathophysiology for these brain lesions.


Subject(s)
Antimetabolites, Antineoplastic/adverse effects , Brain/metabolism , Cranial Irradiation/adverse effects , Methotrexate/adverse effects , Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Adolescent , Adult , Antimetabolites, Antineoplastic/administration & dosage , Aspartic Acid/analogs & derivatives , Aspartic Acid/metabolism , Brain/drug effects , Brain/radiation effects , Brain Infarction/chemically induced , Brain Infarction/etiology , Brain Infarction/metabolism , Cerebrovascular Disorders/chemically induced , Cerebrovascular Disorders/etiology , Cerebrovascular Disorders/metabolism , Child , Choline/metabolism , Creatine/metabolism , Female , Humans , Injections, Spinal , Magnetic Resonance Spectroscopy , Male , Methotrexate/administration & dosage , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/radiotherapy , Radiation Injuries/etiology , Radiation Injuries/metabolism , Time Factors
13.
Chest ; 96(2): 438-9, 1989 Aug.
Article in English | MEDLINE | ID: mdl-2752834

ABSTRACT

Tuberculous pleural effusions are characterized by the absence or paucity of mesothelial cells. Two cases of pleural tuberculosis are reported in which significant numbers of mesothelial cells were found.


Subject(s)
Tuberculosis, Pleural/pathology , Adult , Humans , Male , Middle Aged , Pleura/pathology , Pleural Effusion/pathology , Serous Membrane/pathology
14.
Chest ; 103(5): 1606-7, 1993 May.
Article in English | MEDLINE | ID: mdl-8486054

ABSTRACT

Severe subcutaneous emphysema following arthroscopy of the shoulder developed in a 62-year-old man. It subsequently evolved into pneumomediastinum with respiratory distress, but the patient recovered spontaneously. To our knowledge, this constitutes the first report of pneumomediastinum caused by subcutaneous emphysema in the shoulder.


Subject(s)
Arthroscopy/adverse effects , Mediastinal Emphysema/etiology , Shoulder Joint , Subcutaneous Emphysema/etiology , Humans , Lung/diagnostic imaging , Male , Mediastinal Emphysema/diagnostic imaging , Middle Aged , Radiography , Subcutaneous Emphysema/complications
15.
Chest ; 93(5): 1099-100, 1988 May.
Article in English | MEDLINE | ID: mdl-2834143

ABSTRACT

A 24-year-old patient presented with hemoptysis. Pulmonary evaluation was unrevealing. After being lost to follow-up, he again presented with worsening symptoms and physical findings of severe pulmonary hypertension. A large left atrial mass was found on echocardiogram. This was subsequently found to be a malignant fibrous histiocytoma. He also had pseudothrombocytopenia due to platelet cold agglutinins. Left atrial masses must be considered in unexplained hemoptysis.


Subject(s)
Heart Neoplasms/complications , Hemoptysis/etiology , Histiocytoma, Benign Fibrous/complications , Thrombocytopenia/complications , Adult , Heart Atria , Heart Neoplasms/diagnosis , Histiocytoma, Benign Fibrous/diagnosis , Humans , Male
16.
AJNR Am J Neuroradiol ; 19(7): 1225-8, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9726458

ABSTRACT

A 67-year-old woman had had a neck mass for 10 years, which recently increased in size. Sonographic, CT, and MR examinations showed a mass in the carotid and posterior spaces (triangle) extending from below the submandibular gland to the supraclavicular fossa, displacing the common carotid artery and the sternomastoid anteriorly. The mass was solid, noncalcified with lobulated outlines, hypoechoic on sonograms, of soft-tissue density on CT scans, isointense on T1-weighted MR images, hyperintense on T2-weighted MR images, and enhanced mildly after injection of contrast material on CT and MR studies. Histologic examination revealed a carcinoma showing thymiclike differentiation, a rare tumor of the neck and thyroid gland.


Subject(s)
Carcinoma/pathology , Head and Neck Neoplasms/pathology , Thymoma/pathology , Aged , Carcinoma/diagnosis , Carcinoma/diagnostic imaging , Carotid Artery, Common/diagnostic imaging , Carotid Artery, Common/pathology , Cell Differentiation , Female , Head and Neck Neoplasms/diagnosis , Head and Neck Neoplasms/diagnostic imaging , Humans , Image Enhancement , Magnetic Resonance Imaging , Neck Muscles/diagnostic imaging , Neck Muscles/pathology , Radiographic Image Enhancement , Thymoma/diagnosis , Thymoma/diagnostic imaging , Thyroid Neoplasms/diagnosis , Thyroid Neoplasms/diagnostic imaging , Thyroid Neoplasms/pathology , Tomography, X-Ray Computed , Ultrasonography
17.
Photochem Photobiol ; 58(1): 49-52, 1993 Jul.
Article in English | MEDLINE | ID: mdl-8378432

ABSTRACT

The (1H-indenyl)thiophene derivatives 2 and 3 were recently reported to be excellent singlet oxygen sensitizers, comparable to alpha-terthienyl (1). The phototoxicity of these compounds was compared, using human erythrocytes, Aedes aegypti mosquito larvae, Daphnia magna, and fish (fathead minnows, Pimephales promelas). The known ranking of the photooxidation properties was found to be a good predictor of phototoxic properties in erythrocytes and mosquito larvae but not in daphnias. All three compounds photosensitized the cleavage of supercoiled pBR322 DNA to the same extent.


Subject(s)
Photosensitizing Agents/toxicity , Thiophenes/toxicity , Aedes/drug effects , Aedes/radiation effects , Animals , DNA, Bacterial/drug effects , DNA, Bacterial/radiation effects , Erythrocytes/drug effects , Erythrocytes/radiation effects , Fishes , Humans , Photochemistry , Photosensitizing Agents/chemistry , Thiophenes/chemistry
18.
J Neuroimaging ; 5(2): 128-30, 1995 Apr.
Article in English | MEDLINE | ID: mdl-7718941

ABSTRACT

The computed tomographic and magnetic resonance appearance of a calvarial aneurysmal bone cyst is described. Both forms of imaging demonstrate an epidural mass in the right occiput. The fluid-fluid levels in the mass on the T2-weighted images are characteristic of, though not specific for, aneurysmal bone cyst.


Subject(s)
Bone Cysts, Aneurysmal/diagnostic imaging , Bone Cysts, Aneurysmal/diagnosis , Magnetic Resonance Imaging , Skull/diagnostic imaging , Skull/pathology , Tomography, X-Ray Computed , Adolescent , Diagnosis, Differential , Humans , Male , Occipital Bone/diagnostic imaging , Occipital Bone/pathology , Osteolysis/diagnosis , Osteolysis/diagnostic imaging
19.
J Pharm Sci ; 87(6): 751-6, 1998 Jun.
Article in English | MEDLINE | ID: mdl-9607954

ABSTRACT

Penetration of model beta-blockers, propranolol, oxprenolol, metaprolol, and nadolol, into dimyristoylphosphatidylcholine (DMPC) monolayers cast on a pH 7.4 phosphate buffer (mu = 0.155 adjusted with NaCl) at 25 degreesC was monitored using a film balance equipped with a Wilhelmy plate for measuring changes in surface pressure. Drug solution (pH 7.4) is injected below the surface of the monolayer. The difference in surface pressure, Delta pi, for each drug concentration added to the monolayer was measured at equilibrium. Delta pi increased with increasing drug concentration. Consistent with the relative lipophilicities, the Delta pi vs drug concentration slopes were as follows: propranolol > metaprolol > oxprenolol > nadolol. The intrinsic surface activity of the beta-blockers was also determined in the absence of the lipid. Differential scanning calorimetry (DSC) measurements were also made on DMPC bilayers in the above buffer. DMPC suspended in buffered drug solutions were scanned over a temperature range of 5 degrees to 40 degreesC at a scan rate of 0.091 degreesC/min. The DSC studies indicate that the DMPC thermotropic phase behavior is modulated by these compounds as follows: propranolol >> metaprolol congruent with oxprenolol > nadolol which agrees with reported partition coefficients as well as the above Delta pi observations. However, an accounting of the intrinsic surface activity of these compounds results in a lower than expected affinity for the DMPC monolayer.


Subject(s)
Adrenergic beta-Antagonists/pharmacokinetics , Dimyristoylphosphatidylcholine/metabolism , Lipid Bilayers/metabolism , Adrenergic beta-Antagonists/chemistry , Calorimetry, Differential Scanning , Solubility
20.
J Photochem Photobiol B ; 21(2-3): 135-42, 1993 Dec.
Article in English | MEDLINE | ID: mdl-8301409

ABSTRACT

Very potent antibiotic antitumor natural products contain a enediyne moiety which, upon thermal activation, is capable of abstracting hydrogens from DNA. 1,6-Diphenyl-3-hexene-1,5-diyne was selected as a candidate for inducing DNA strand breaks photochemically. Easily interconverted with light, both geometric isomers 1 and 2 were expected to be phototoxic. As anticipated, they photosensitized the production of strand breaks in double-stranded supercoiled pBR322, and in single-stranded M13 DNA. The DNA cleavage reactions were favored by the presence of oxygen and were inhibited by ethanol. Preliminary experiments with the (Z)-isomer indicated moderate light-dependent antiviral activity against human immunodeficiency virus (HIV), Sindbis virus, and mouse cytomegalovirus. The enediynes were cytotoxic to Escherichia coli, a gram-negative organism, to Streptococcus faecalis, a gram-positive organism, to Daphnia magna and to fish (Pimephales promelas), but only in the presence of light. The production of o-terphenyl, the expected product of Bergman cyclization of 1, could not be confirmed. However, both 1 and 2 photosensitized the formation of singlet oxygen and of superoxide anion radical, and photodynamic reactions could have been responsible for some of the phototoxic reactions observed.


Subject(s)
Alkynes/toxicity , DNA Damage , Photosensitizing Agents/toxicity , 3T3 Cells , Alkynes/chemistry , Animals , Bacteriophage M13 , DNA, Viral/drug effects , Daphnia/drug effects , Diynes , Enterococcus faecalis/drug effects , Escherichia coli/drug effects , Fishes , Isomerism , Mice , Oxygen/analysis , Photochemistry , Plasmids/drug effects , Singlet Oxygen , Spectrophotometry , Superoxides/analysis
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