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1.
Hong Kong Med J ; 27(2): 99-105, 2021 04.
Article in English | MEDLINE | ID: mdl-33790053

ABSTRACT

INTRODUCTION: The Hospital Authority of Hong Kong Special Administrative Region established a coronavirus disease 2019 (COVID-19) temporary test centre at the AsiaWorld-Expo from March 2020 to April 2020, which allowed high-risk individuals to undergo early assessment of potential severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This study reviewed the characteristics and outcomes of individuals who attended the centre for COVID-19 testing. METHODS: This retrospective cross-sectional study collected epidemiological and clinical data. The primary outcome was a positive or negative SARS-CoV-2 test result, according to reverse transcription polymerase chain reaction analyses of pooled nasopharyngeal and throat swabs collected at the centre. The relationships of clinical characteristics with SARS-CoV-2 positive test results were assessed by multivariable binary logistic regression. RESULTS: Of 1258 attendees included in the analysis, 86 individuals tested positive for SARS-CoV-2 infection (positivity rate=6.84%; 95% confidence interval [CI]=5.57%-8.37%). Of these 86 individuals, 40 (46.5%) were aged 15 to 24 years and 81 (94.2%) had a history of recent travel. Symptoms were reported by 86.0% and 96.3% of individuals with positive and negative test results, respectively. The clinical characteristics most strongly associated with a positive test result were anosmia (adjusted odds ratio [ORadj]=8.30; 95% CI=1.12-127.09) and fever ORadj=1.32; 95% CI=1.02-3.28). CONCLUSION: The temporary test centre successfully helped identify individuals with COVID-19 who exhibited mild disease symptoms. Healthcare providers should carefully consider the epidemiological and clinical characteristics of COVID-19 to arrange early testing to reduce community spread.


Subject(s)
COVID-19 Testing , COVID-19 , Disease Transmission, Infectious/prevention & control , Quick Diagnosis Units , SARS-CoV-2/isolation & purification , Adolescent , Adult , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/physiopathology , COVID-19 Testing/methods , COVID-19 Testing/statistics & numerical data , Cross-Sectional Studies , Female , Hong Kong/epidemiology , Humans , Male , Quick Diagnosis Units/methods , Quick Diagnosis Units/organization & administration , Quick Diagnosis Units/statistics & numerical data , Symptom Assessment/statistics & numerical data , Travel-Related Illness
3.
Patient Educ Couns ; 100(10): 1890-1897, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28599868

ABSTRACT

OBJECTIVE: This study identified the profiles of subgroups of type 2 diabetic (T2DM) patients of the Patient Empowerment Programme (PEP) by different levels of benefits gained in diabetic self-management behaviors, self-efficacy, and health literacy. METHODS: This study adopted a non-experimental repeated-measures design on T2DM patients who joined PEP, using structured questionnaires. Latent profile analysis (LPA) was used to identify patterns of participants' change on the outcome measures. RESULTS: Findings of LPA revealed that participants who were older, unemployed, weaker in diabetic self-management, and having a higher self-perception in personal disease risk were more likely to join the empowerment sessions and gained more benefits from the program. Participants with lower impairment in energy function and lower autonomy in personal health care showed more improvement in the outcomes. CONCLUSION: The study identified significant factors associated with patients' participation on and benefits gained from a service delivery model integrating health education and patient empowerment in a primary care setting. PRACTICE IMPLICATION: Findings from this study shed light on strategies to improve the PEP design in order to meet the needs of individuals with different health-related profiles.


Subject(s)
Diabetes Mellitus, Type 2/therapy , Health Knowledge, Attitudes, Practice , Patient Education as Topic/methods , Patient Participation , Power, Psychological , Primary Health Care , Self Efficacy , Adult , Aged , Diabetes Mellitus, Type 2/psychology , Female , Health Literacy , Humans , Middle Aged , Outcome Assessment, Health Care , Self Care , Surveys and Questionnaires
4.
Diabetes Obes Metab ; 17(2): 128-35, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25251664

ABSTRACT

AIMS: To assess whether a structured diabetes education programme, the Patient Empowerment Programme (PEP), was associated with a lower risk of first cardiovascular disease (CVD) event and all-cause mortality in a population-based cohort of patients with type 2 diabetes mellitus (T2DM) in primary care. METHODS: A Chinese cohort of 27 278 patients with T2DM and without previous CVD events on or before the baseline study recruitment date was linked to the Hong Kong administrative database from 2008 to 2013. The PEP was provided to patients with T2DM treated at primary care outpatient clinics through community trained professional educators. PEP non-participants were matched one-to-one with the PEP participants using a propensity score method with respect to their baseline covariates. Cox proportional hazard regression was performed to estimate the associations of the PEP with the occurrence of first CVD event, coronary heart disease, stroke, heart failure and death from any cause, controlling for baseline characteristics. RESULTS: During a median of 21.5 months follow-up, 795 (352 PEP participants and 443 PEP non-participants) patients experienced a first CVD event. After adjusting for confounding variables, PEP participants had a lower rate of all-cause mortality [hazard ratio (HR) 0.564, 95% confidence interval (CI) 0.445-0.715; p < 0.001], first CVD (HR 0.807, 95% CI 0.696-0.935; p = 0.004) and stroke (HR 0.702; 95% CI 0.569-0.867; p = 0.001) than those without PEP. CONCLUSIONS: Enrolment in the PEP was associated with lower all-cause mortality and a lower number of first CVD events among patients with T2DM. The CVD benefit of PEP might be attributable to improving metabolic control through empowerment of self-care and the enhancement of quality of diabetes care in primary care.


Subject(s)
Asian People/statistics & numerical data , Cardiovascular Diseases/prevention & control , Diabetes Mellitus, Type 2/complications , Diabetic Angiopathies/prevention & control , Patient Participation , Primary Health Care , Self Care , Cardiovascular Diseases/etiology , Cardiovascular Diseases/mortality , Follow-Up Studies , Hong Kong/epidemiology , Humans , Incidence , Patient Compliance , Patient Education as Topic , Program Evaluation , Propensity Score , Proportional Hazards Models , Risk Factors
5.
Pediatr Surg Int ; 30(7): 747-9, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24828888

ABSTRACT

OBJECTIVE: It is suggested that idiopathic constipation may associate with abnormal voiding parameters. In this study, we investigate the voiding parameters in children with constipation. METHODS: Since 2010, seventeen consecutive children (12 boys, 5 girls) aged 5-17 (median = 14) with significant constipation according to Rome III criteria and who were not responding to conventional treatment (diet, laxatives & bowel training) for over 6 months were recruited. The rectal diameter (RD) was measured by transpubic ultrasonography (USG), RD >3.5 cm was considered as dilated. Each patient had uroflow measurement and bladder USG done to measure the maximal flow rate (Vmax), voided volume (VV), and post-void residual urine (PVR). Abnormal voiding parameters were defined as Vmax <12 ml/sec, VV <65 or >150% of age-adjusted expected bladder capacity (EBC) and/or PVR >20 ml. RESULTS: Rectal diameter ranged from 1.7 to 8.2 cm (median = 3 cm) and was abnormally dilated in eight children. Vmax was normal in all children (median = 23.7 ml/sec). Voided volume ranged from 30 to 289% of EBC and was abnormal in six children (35.5%). Post-void residual urine varied from 0 to 85 ml and was abnormal in six (35.5 %) children. Three children (17.6 %) had both abnormal VV and PVR. On the whole, the prevalence of abnormal voiding parameters in constipated children was 52.9 %. Mean RD in normal and abnormal parameters groups was 2.8 and 4.7 cm, respectively. Rectal dilation was associated with abnormal voiding parameters (p = 0.015). CONCLUSION: Abnormal voiding parameters including voided volume and post-void residual urine are prevalent in constipated children. Dilated rectum is associated with abnormal voiding parameters.


Subject(s)
Constipation/complications , Urinary Bladder/physiopathology , Urinary Retention/etiology , Urination , Adolescent , Child , Child, Preschool , Constipation/diagnostic imaging , Constipation/physiopathology , Defecation , Diagnosis, Differential , Female , Humans , Male , Rectum/diagnostic imaging , Rectum/physiopathology , Severity of Illness Index , Ultrasonography , Urinary Bladder/diagnostic imaging , Urinary Retention/diagnostic imaging , Urinary Retention/physiopathology
6.
PLoS One ; 9(5): e95328, 2014.
Article in English | MEDLINE | ID: mdl-24788804

ABSTRACT

BACKGROUND: To evaluate the effects of a large population-based patient empowerment programme (PEP) on clinical outcomes and health service utilization rates in type 2 diabetes mellitus (T2DM) patients in the primary care setting. RESEARCH DESIGN AND SUBJECTS: A stratified random sample of 1,141 patients with T2DM enrolled to PEP between March and September 2010 were selected from general outpatient clinics (GOPC) across Hong Kong and compared with an equal number of T2DM patients who had not participated in the PEP (non-PEP group) matched by age, sex and HbA1C level group. MEASURES: Clinical outcomes of HbA1c, SBP, DBP and LDL-C levels, and health service utilization rates including numbers of visits to GOPC, specialist outpatient clinics (SOPC), emergency department (ED) and inpatient admissions, were measured at baseline and at 12-month post-recruitment. The effects of PEP on clinical outcomes and health service utilization rates were assessed by the difference-in-difference estimation, using the generalized estimating equation models. RESULTS: Compared with non-PEP group, PEP group achieved additional improvements in clinical outcomes over the 12-month period. A significantly greater percentage of patients in the PEP group attained HbA1C≤7% or LDL-C≤2.6 mmol/L at 12-month follow-up compared with the non-PEP group. PEP group had a mean 0.813 fewer GOPC visits in comparison with the non-PEP group. CONCLUSIONS: PEP was effective in improving the clinical outcomes and reduced the general outpatient clinic utilization rate over a 12-month period. Empowering T2DM patients on self-management of their disease can enhance the quality of diabetes care in primary care. TRIAL REGISTRATION: ClinicalTrials.gov NCT01935349.


Subject(s)
Diabetes Mellitus, Type 2/epidemiology , Health Services , Patient Participation , Primary Health Care , Aged , Ambulatory Care Facilities , Biomarkers/metabolism , Cohort Studies , Comorbidity , Diabetes Mellitus, Type 2/metabolism , Female , Hong Kong/epidemiology , Humans , Male , Middle Aged , Outcome Assessment, Health Care , Risk Factors
7.
Pediatr Surg Int ; 30(1): 107-11, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24085513

ABSTRACT

AIM OF THE STUDY: Anatomical variations on venous drainage in varicoceles are under-reported. We report our experience in scrotal antegrade sclerotherapy (SAS) for adolescent varicoceles. METHODS: Since 2011, 15 consecutive boys with left varicoceles were recruited. Under general anaesthesia, a 5-mm transverse incision was made at scrotal neck, testicular vein was cannulated at pampiniform plexus with venogram performed. Foam sclerosant by mixing sodium tetradecyl sulphate (STS), Lipiodol(®) and air was slowly injected under fluoroscopy. Postoperatively the patients were followed-up for varicocele grading, testicular size, and complications. MAIN RESULTS: Median age at operation was 14 (10-19) years. 80 % had grade three varicoceles, 33.3 % had smaller left testis before operation. Intra-operative venogram showed three different anatomical variations. Group I: eleven patients (73.3 %) had single distinct internal spermatic vein; Group II: two patients demonstrated duplication of internal spermatic vein draining into left renal vein; Group III: two patients had pampiniform plexus draining to iliac and/or paraspinal veins. SAS was performed in Group I and II patients. Sclerosant volume injected ranged from 1.5 to 4.5 ml. In Group III patients, surgical ligation of testicular veins was performed rather than SAS to avoid uncontrolled systemic sclerosant spillage. Mean length of stay was 1.13 day. One patient with scrotal haematoma and one other with minor wound dehiscence were managed conservatively. Mean follow-up period was 10.9 (1-22) months. Thirteen patients (86.7 %) achieved varicocele grading ≤ 1. There was no postoperative testicular atrophy, hydrocele and epididymo-orchitis. CONCLUSION: Scrotal antegrade sclerotherapy using STS foam is a safe and effective treatment for adolescent varicoceles. Anatomical variations on venous drainage in varicoceles are common.


Subject(s)
Sclerotherapy/methods , Scrotum/blood supply , Varicocele/therapy , Adolescent , Adult , Child , Follow-Up Studies , Humans , Male , Sclerosing Solutions/therapeutic use , Scrotum/anatomy & histology , Sodium Tetradecyl Sulfate/therapeutic use , Testis/anatomy & histology , Testis/blood supply , Treatment Outcome , Young Adult
8.
Hong Kong Med J ; 10(3): 191-5, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15181224

ABSTRACT

OBJECTIVES: To review potential risks of eye medications to the mother and her foetus. DATA SOURCES: PubMed search for all relevant articles (1966 to 2003). STUDY SELECTION: All types of publication that documented potential risks of eye medications during pregnancy. The following key words were used: pregnancy, fetus, teratogenicity, eye, ocular, ophthalmic, glaucoma, antibiotics, anti-inflammatory, and corticosteroids. DATA EXTRACTION: All relevant articles including original articles, review papers, case studies, and relevant book chapters were extracted and reviewed. DATA SYNTHESIS: Whether ophthalmic medications can be used during pregnancy is a very important issue; yet, limited information on the subject exists in the literature. Topically applied eye medications that give rise to systemic side-effects are of particular concern to both patients and doctors. Various ophthalmic anti-infective preparations and ophthalmic corticosteroids have shown to cause teratogenicity in animal studies. Furthermore, anti-glaucoma drugs pose potential risks to the foetus if they are absorbed systemically. This article examines the association between the main groups of ophthalmic medication and their possible adverse effects on the mother and the foetus. Recommendations for the treatment of pregnant patients with eye diseases are also discussed. CONCLUSION: The risk of giving ophthalmic drugs to pregnant women is low. Doctors should be cautious when prescribing drugs for pregnant women and consult experts in the field when in doubt.


Subject(s)
Eye Diseases/drug therapy , Adrenal Cortex Hormones/therapeutic use , Anti-Allergic Agents/therapeutic use , Anti-Infective Agents/therapeutic use , Anti-Inflammatory Agents/therapeutic use , Female , Humans , Pregnancy , Pregnancy Complications/prevention & control
9.
IEEE Trans Image Process ; 9(12): 2109-16, 2000.
Article in English | MEDLINE | ID: mdl-18262948

ABSTRACT

Based on the space-filling approach, this paper presents a fast algorithm for window query on compressed images. Given a query window of size n1xn2, the proposed algorithm takes O(n1logT+P) time to perform the window query, where n1=max(n1, n2) and TxT is the image size; P is the number of outputted codes. The proposed algorithm improves the naive algorithm, which needs O(n1n2logT+P) time, significantly. Some experimentations are carried out to demonstrate the computational advantage of the proposed algorithm. From the experimental results, it is observed that the proposed algorithm has about 72-98% time improvement when compared to the naive algorithm.

10.
Kaohsiung J Med Sci ; 12(9): 495-502, 1996 Sep.
Article in Japanese | MEDLINE | ID: mdl-8819352

ABSTRACT

Tc(V)-99m DMS, developed by Yokoyama et al. in 1981, has been recognized to be advantageous for the scintigraphic diagnosis of various malignant tumors and their metastasis, the aim of this study is to assess the in-vitro stability of Tc(V)-99m DMS. Thin-layer chromatography, including paper chromatography and silica gel thin layer chromatography, is performed to determine the change of radiochemical species presented in the reconstituted solution of Tc(V)-99m DMS prepared from the DMS kit (Institute of Nuclear Energy Research, Atomic Energy Council R.O.C.) and the commercial DMSA kit (Nephroscint, IRE CELLTARG Radiopharmaceuticals Japan). The bioscan imaging scanner is used to measure the Rf value and labeling efficiency of radiochemical species on the chromatographic strip. The in-vitro stability of Tc(V)-99m DMS prepared from the DMS kit and the commercial DMSA kit is studied by examining various parameters which include temperature(degree C) and time(hr) after reconstitution. The results show that the in-vitro stability of Tc(V)-99m DMS prepared from the DMS kit is actually better than that from the commercial DMSA kit. The one-step labeling method of DMS kit is much simpler than the two-step labeling method of DMSA kit.


Subject(s)
Organotechnetium Compounds/chemistry , Succimer/chemistry , Drug Stability , Technetium Tc 99m Dimercaptosuccinic Acid
11.
Appl Ergon ; 27(4): 255-65, 1996 Aug.
Article in English | MEDLINE | ID: mdl-15677066

ABSTRACT

The purpose of this research was to develop a new model to describe and predict a computerized task. AutoCAD was utilized as the experimental tool to collect operating procedure and time data at a keystroke level for a computer aided design (CAD) task. Six undergraduate students participated in the experiment. They were required to complete one simple and one complex engineering drawing. A model which characterized the task performance by software commands and predicted task execution time using keystroke-level model operators was proposed and applied to the analysis of the dialogue data. This task parameter model adopted software commands, e.g. LINE, OFFSET in AutoCAD, to describe the function of a task unit and used up to five parameters to indicate the number of keystrokes, chosen function for a command and ways of starting and ending a command. Each task unit in the task parameter model can be replaced by a number of primitive operators as in the keystroke level model to predict the task execution time. The observed task execution times of all task units were found to be highly correlated with the task execution times predicted by the keystroke level model. Therefore, the task parameter model was proved to be a usable analytical tool for evaluating the human-computer interface (HCI).

12.
Environ Health Perspect ; 103 Suppl 7: 113-22, 1995 Oct.
Article in English | MEDLINE | ID: mdl-8593856

ABSTRACT

Estrogens are defined by their ability to induce the proliferation of cells of the female genital tract. The wide chemical diversity of estrogenic compounds precludes an accurate prediction of estrogenic activity on the basis of chemical structure. Rodent bioassays are not suited for the large-scale screening of chemicals before their release into the environment because of their cost, complexity, and ethical concerns. The E-SCREEN assay was developed to assess the estrogenicity of environmental chemicals using the proliferative effect of estrogens on their target cells as an end point. This quantitative assay compares the cell number achieved by similar inocula of MCF-7 cells in the absence of estrogens (negative control) and in the presence of 17 beta-estradiol (positive control) and a range of concentrations of chemicals suspected to be estrogenic. Among the compounds tested, several "new" estrogens were found; alkylphenols, phthalates, some PCB congeners and hydroxylated PCBs, and the insecticides dieldrin, endosulfan, and toxaphene were estrogenic by the E-SCREEN assay. In addition, these compounds competed with estradiol for binding to the estrogen receptor and increased the levels of progesterone receptor and pS2 in MCF-7 cells, as expected from estrogen mimics. Recombinant human growth factors (bFGF, EGF, IGF-1) and insulin did not increase in cell yields. The aims of the work summarized in this paper were a) to validate the E-SCREEN assay; b) to screen a variety of chemicals present in the environment to identify those that may be causing reproductive effects in wildlife and humans; c) to assess whether environmental estrogens may act cumulatively; and finally d) to discuss the reliability of this and other assays to screen chemicals for their estrogenicity before they are released into the environment.


Subject(s)
Environmental Pollutants/analysis , Estrogens/analysis , Xenobiotics/analysis , Animals , Antioxidants/analysis , Binding, Competitive , Biological Assay , Cell Division/drug effects , Disease Models, Animal , Drug Evaluation, Preclinical , Female , Humans , Pesticides/analysis , Plasticizers/analysis , Polychlorinated Biphenyls/analysis , Receptors, Progesterone/biosynthesis , Receptors, Progesterone/drug effects , Tumor Cells, Cultured
13.
Environ Health Perspect ; 102(4): 380-3, 1994 Apr.
Article in English | MEDLINE | ID: mdl-7925178

ABSTRACT

Estrogenic pesticides such as DDT and chlordecone generate deleterious reproductive effects. An "in culture" bioassay was used to assess the estrogenicity of several pesticides. The E-screen test uses human breast estrogen-sensitive MCF7 cells and compares the cell yield achieved after 6 days of culture in medium supplemented with 5% charcoal-dextran stripped human serum in the presence (positive control) or absence (negative control) of estradiol and with diverse concentrations of xenobiotics suspected of being estrogenic. Among the organochlorine pesticides tested, toxaphene, dieldrin, and endosulfan had estrogenic properties comparable to those of DDT and chlordecone; the latter are known to be estrogenic in rodent models. The E-screen test also revealed that estrogenic chemicals may act cumulatively; when mixed together they induce estrogenic responses at concentrations lower than those required when each compound is administered alone.


Subject(s)
Dieldrin/adverse effects , Endosulfan/adverse effects , Receptors, Estrogen/drug effects , Toxaphene/adverse effects , Biological Assay , Breast Neoplasms/pathology , Cell Division/drug effects , Drug Synergism , Female , Humans , Tumor Cells, Cultured
14.
Pediatr Nurs ; 20(1): 58-63, 1994.
Article in English | MEDLINE | ID: mdl-8159486

ABSTRACT

PURPOSE: 1. To determine the accuracy, precision, specificity, sensitivity, positive prediction, and negative prediction of TempaDOT, FirstTEMP, and Genius as compared to the glass mercury thermometer; 2. To determine the influence of age, behavior, febrile status, tympanic membrane bulge, presence of ear wax, and site on temperature readings; and 3. To determine the ability of each instrument to detect a shift in temperature after Tylenol. METHOD: A quasi-experimental, multiple-correlational design was used to study 960 temperature measurements obtained on 89 febrile and 83 afebrile children in an emergency unit. FINDINGS: TempaDOT was found to be the most accurate and most precise instrument for children ages 5 years and under with and without fevers. FirstTEMP was found to be most sensitive for temperatures above 37.5 degrees C and best in detecting shifts after Tylenol was given. Age, behavior, febrile status or tympanic membrane bulge did not significantly affect accuracy. The most accurate sites in order of accuracy were: oral axillary, aural, rectal. The order of precision of sites was: oral, aural, rectal, and axillary. Behavior did not significantly affect the precision. CONCLUSION: TempaDOT was found to be the most clinically useful temperature measurement instrument. FirstTEMP may be used as a screening tool to determine if antipyretic medication is working to decrease fevers. TempaDOT is recommended for use in emergency units to validate the presence or absence of fevers in children especially when the FirstTEMP reading is near 37.0-38.8 degrees C.


Subject(s)
Body Temperature , Fever/diagnosis , Thermometers/standards , Child , Child, Preschool , Clinical Nursing Research , Emergency Service, Hospital , Fever/epidemiology , Fever/nursing , Humans , Infant , Reproducibility of Results , Sensitivity and Specificity
15.
ASDC J Dent Child ; 54(4): 241-4, 1987.
Article in English | MEDLINE | ID: mdl-3476523

ABSTRACT

This study compared the anticaries effects of these three fluoride-containing dentifrices: 1100 ppm F as NaF (positive control); 2800 ppm F as SMFP; and 2800 ppm F as NaF. The group using the 2800 SMFP dentifrice showed no significant differences in DMFS or DMFT, compared to the positive control, at anytime during the study. This indicated that higher levels of sodium monofluorophosphate in a dentifrice offer no advantage in caries protection over the conventional level of sodium fluoride, 1100 ppm F.


Subject(s)
Dental Caries/prevention & control , Fluorides/administration & dosage , Phosphates/administration & dosage , Sodium Fluoride/administration & dosage , Adolescent , Child , DMF Index , Double-Blind Method , Female , Humans , Male , Toothpastes
16.
J Gen Virol ; 64 (Pt 7): 1531-42, 1983 Jul.
Article in English | MEDLINE | ID: mdl-6306151

ABSTRACT

A mutant (m-29) of Autographa californica nuclear polyhedrosis virus (AcMNPV) grew in Spodoptera frugiperda and Trichoplusia ni cells but did not form typical intranuclear occlusion bodies (OB); instead, small particles (95 to 180 nm diam.) were produced in copious amounts within nuclei. Ultrastructural studies showed that the particles did not occlude enveloped nucleocapsids and that they lacked a macromolecular paracrystalline lattice and a structure equivalent to the occlusion body envelope. The particles within nuclei stained in an immunofluorescence test with antipolyhedrin antibody and when extracted from cells the major polypeptide of a particle preparation was indistinguishable from polyhedrin when examined on SDS--polyacrylamide gels and had an identical peptide pattern following proteolysis with V8 protease. Other elements believed to be implicated in OB morphogenesis such as a proliferation of intranuclear membranes, enveloped bundles of nucleocapsids, patches of fibrous material and fibrous sheets were present in normal amounts. No alteration in the synthesis or processing of polypeptides was seen in mutant-infected cells. Analysis of m-29 DNA with BamHI, EcoRI and HindIII restriction endonucleases revealed that the HindIII restriction site at the F/V junction of viral DNA was absent in the mutant. No other modifications in the restriction patterns were detected. It is proposed that an alteration in the amino acid sequence of polyhedrin towards the--NH2 terminus of the polypeptide may account for the growth characteristics of the mutant.


Subject(s)
Insect Viruses/genetics , Mutation , Animals , DNA Restriction Enzymes , DNA, Viral/genetics , Fluorescent Antibody Technique , Insect Viruses/isolation & purification , Insect Viruses/ultrastructure , Insecta , Microscopy, Electron , Morphogenesis , Nucleic Acid Hybridization , Species Specificity , Viral Proteins/genetics
17.
Dev Comp Immunol ; 6(3): 433-40, 1982.
Article in English | MEDLINE | ID: mdl-6813153

ABSTRACT

The ultrastructure of Pseudomonas aeruginosa, a pathogen of Galleria mellonella is rapidly altered after in vitro exposure to the hemolymph of vaccinated larvae. The bacteria were treated with normal and immune hemolymph for periods of time ranging from 7 to 28 min at 28 degrees C. In contrast to the apparent non-damaging effects of normal hemolymph, the immune hemolymph caused progressive damage to the cells within 7 min. The initial attack was directed towards the cell wall. Complete degradation was observed after 14 to 28 min exposure to the immune hemolymph.


Subject(s)
Hemolymph/physiology , Lepidoptera/immunology , Moths/immunology , Pseudomonas aeruginosa/ultrastructure , Animals , Bacterial Infections/immunology , Bacterial Infections/microbiology , Blood Bactericidal Activity , Hemolymph/immunology , Larva/immunology , Time Factors
19.
Can J Microbiol ; 23(12): 1706-13, 1977 Dec.
Article in English | MEDLINE | ID: mdl-340019

ABSTRACT

The effect of rifampicin on the developmental phases of germinating spores of Clostridium botulinum, MSp+, has been studied. At sublethal concentrations of rifampicin (0.05 ng/ml) the time periods required for outgrowth and vegetative growth was significantly prolonged because of the inhibition of RNA and protein synthesis. However, rifampicin had essentially no effect on DNA synthesis or on subsequent spore formation. Chemical analyses showed that the amount of protein present in vegetative cells of the rifampicin-treated cultures was twice as great as in the untreated cultures but the total protein content of endospores was the same in both cases. It was revealed in ultrastructural studies of rifampicin (0.1 ng/ml) treated cultures, examined after 22 h, that septum formation and normal cell division of the emerging cell was blocked and a few cells showed constriction which produced one normal and one protoplast-like daughter cell.


Subject(s)
Clostridium botulinum/drug effects , Rifampin/pharmacology , Bacterial Proteins/biosynthesis , Cell Cycle , Clostridium botulinum/growth & development , Clostridium botulinum/ultrastructure , DNA, Bacterial/biosynthesis , Microscopy, Electron , RNA, Bacterial/biosynthesis , Spores
20.
J Gen Microbiol ; 92(1): 81-8, 1976 Jan.
Article in English | MEDLINE | ID: mdl-1107487

ABSTRACT

Sublethal doses of rifampin (0-005 mug/ml), added to vegetatively growing cultures of a sporogenic mutant of Clostridium botulinum at inoculation time or after 4 h, resulted in a decrease of growth and in blockage of spore formation. But when rifampin was added 6 to 24 h after inoculation, normal growth and sporulation occurred, indicating that the time of addition was critical and that rifampin was most effective on rapidly dividing, exponential-phase cells. Ultrastructural studies showed that when rifampin was added at the time of inoculation, endospore development was blocked at stage III. During subsequent incubation (greater than 10 h) the cells lost their rigidity, and lysis of the mother cell was followed by that of the forespore. When the cultures were treated with rifampin at 4 h, about 40% of the cells were blocked at stage III and about 60% reached stages IV and V. Some showed excessive elongation and contained developing spores at each pole. They appeared to be derived from two daughter cells unable to form a division septum because of a specific inhibitory effect of rifampin on division. It would seem, therefore, that two daughter cells which are genetically coded to form endospores will do so irrespective of the development of a division septum, and the spores are formed at the 'old' polar regions.


Subject(s)
Clostridium botulinum/drug effects , Rifampin/pharmacology , Clostridium botulinum/growth & development , Clostridium botulinum/ultrastructure , Cytoplasmic Granules/ultrastructure , Dose-Response Relationship, Drug , Hydroxybutyrates , Spores, Bacterial/growth & development , Spores, Bacterial/ultrastructure
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