Biomedical subjects
Publications and source records attributed to C Kwan.
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A 34-year-old lady developed a constellation of dermatitis, fever, lymphadenopathy and hepatitis, beginning on the 17th day of a course of oral sulphasalazine for sero-negative rheumatoid arthritis. Cervical and inguinal lymph node biopsies showed the features of severe necrotising lymphadenitis, associated with erythrophagocytosis and prominent eosinophilic infiltrates, without viral inclusion bodies, suggestive of an adverse drug reaction.A week later, fulminant drug-induced hepatitis, associated with the presence of anti-nuclear autoantibodies (but not with other markers of autoimmunity), and accompanied by multi-organ failure and sepsis, supervened. She subsequently died some 5 weeks after the commencement of her drug therapy.Post-mortem examination showed evidence of massive hepatocellular necrosis, acute hypersensitivity myocarditis, focal acute tubulo-interstitial nephritis and extensive bone marrow necrosis, with no evidence of malignancy. It is thought that the clinico-pathological features and chronology of this case bore the hallmarks of the so-called "3-week sulphasalazine syndrome", a rare, but often fatal, immunoallergic reaction to sulphasalazine.
We developed supercritical fluid procedures for extracting vitamin A and beta-carotene from vitamin supplements and calf liver tissue. The SF extracts could be injected onto an HPLC column without further pretreatment. Samples were analysed by RP-HPLC using diode array detection or by spectrophotometry. Recoveries were very good. SF extracts from a vitamin preparation of uniform composition had an R.S.D. of 4%. Extracts from calf liver supplements were predictably more heterogeneous. The SF extraction method is less labor intensive then traditional liquid-liquid procedures for extracting vitamin A and carotenoids from tissues.
A report of a rare case of hemangioma of the ethmoidal sinuses with erosion of bony orbital wall and anterior cranial fossa. An outline of the management is presented.
Prior work has indicated that the polycistronic lacZYA mRNA of Escherichia coli is cleaved during decay at approximately intergenic sites (L. W. Lim and D. Kennell, J. Mol. Biol. 135: 369-390, 1979). In this work, we characterized the products by using probes specific for the different cistrons. This analysis indicated that six lac mRNA species are present in the following order of decreasing abundance: lacZ, -A, -ZYA, -ZY, -YA, and -Y. Very little lacYA and lacY mRNAs were present, whereas in cells induced to steady state, there was 10 times more lacZ than lacZYA mRNA. The lacZ mRNA appeared as a discrete species extending to a site in the lacZ-Y intergenic space (ca. residue 3150). This site is just distal to a potential rho-independent termination sequence. We examined the function of this sequence to determine whether it contributes to the distribution of the mRNAs. Although the termination sequence was shown to function in vitro, when it was recloned into an expression vector, no termination was seen in vivo. Moreover, direct examination of the kinetics of lac messenger synthesis revealed that after initiation, most transcription continued to the end of the operon. We conclude that during normal growth, the operon is transcribed in its entirety and that the individual lac mRNAs are formed by cleavage. These results confirm earlier work implying that the lac operon is transcribed in its entirety but are in conflict with several recent reports suggesting that internal termination occurs. Our findings indicate that the natural polarity of the operon (lacZ is expressed sixfold more strongly than lacA) is based on posttranslational effects and not on polarity of transcription.
Choroidal melanoma is extremely rare in our population. We report three cases with varied presentations. Two patients presented late with secondary lens induced and neovascular glaucoma, and one patient had early presentation of metamorphosia. We would like to emphasise the importance of an ultrasound scan before any intraocular surgery where the view of the fundus is obscured by an opaque ocular media. A proper ultrasound diagnosis avoids unnecessary surgery which could cause tumour dissemination. Two cases were enucleated and one was managed conservatively.
To determine if there are any unique features of nursing home-acquired pneumonia we carried out a case-control study wherein each patient admitted with nursing home-acquired pneumonia was age- and sex-matched with a patient with community-acquired pneumonia. There were 36 men and 38 women in the nursing home group. The mean age of both groups was 74 years. The mortality rate for nursing home-acquired pneumonia it was 40.5%, whereas for community-acquired pneumonia it was 28% (P = NS). Patients with nursing home-acquired pneumonia had a significantly higher incidence of dementia and cerebrovascular accidents, and patients with community-acquired pneumonia were more likely to be smokers and to have chronic obstructive pulmonary disease. Aspiration pneumonia was more common among patients with nursing home-acquired pneumonia (P less than .001), and Hemophilus influenza pneumonia more common among the patients with community-acquired infection (P less than .01). Sputum for culture could be obtained in only 31 and 39% of the patients--contributory to the high rates of pneumonia of unknown etiology 63.5 and 56.1% for the nursing home group and the control subjects, respectively. Patients with nursing home-acquired pneumonia received cloxacillin and aminoglycosides more frequently than patients with community-acquired pneumonia (P less than .05), and patients with community-acquired pneumonia received erythromycin more frequently than patients with nursing home-acquired pneumonia (P less than .05). Complications were common during the hospital stay of these patients--the most frequent being congestive heart failure, urinary tract infection, renal failure, and respiratory failure.
The authors studied 138 patients, 57 of whom were younger than 65 years of age and 81 who were 65 years of age and older, with community-acquired pneumonia to determine whether or not such pneumonia is different in the elderly and to define how such patients are investigated and treated. Pneumonia in the elderly was characterized by a higher mortality, 30 v 10%; more likely to be of unknown etiology, 54 v 30%; and more likely to show radiographic progression after the patient had been admitted to the hospital, 48 v 11%. In addition, elderly patients were more likely to be afebrile when admitted, 57 v 26%. Twenty-seven etiologic categories were present in 77 patients in whom a cause for the pneumonia was established. Streptococcus pneumoniae accounted for 9.4% of the pneumonia overall and for 27% of the pneumonia among patients who had sputum cultures performed before antibiotic therapy. The diagnostic yield was 11.6% for blood cultures, 38.2% for sputum cultures, 2.3% for throat washing, and 22.1% for serological studies. Twenty-seven percent of patients were receiving antibiotics of the time of admission to the hospital. Most (79%) received more than one antibiotic after admission. This study indicates that community-acquired pneumonia is a serious illness and that an algorithm approach to diagnosis and treatment of such pneumonia is necessary.
We used the indirect microimmunofluorescence test to determine the presence of antibodies in sheep, cattle, goat, cat, and dog sera to phase I and II Coxiella burnetii antigens in Nova Scotia. Only 6.7 per cent of the 329 sheep tested had antibodies to phase II antigen and none had antibodies to phase I. Of 29 goats tested, 7 per cent and 3.5 per cent had antibodies to phase II and phase I antigens, respectively. In contrast, 23.8 per cent of the 214 cattle tested had antibodies to phase II antigen, and 24.2 per cent had antibodies to phase I antigen; 24.1 per cent of 216 cats tested had antibodies to phase II antigen and 6 per cent had antibodies to phase I antigen. None of the 447 dogs tested had antibodies detected. We conclude that cattle and cats may be reservoirs for human Q fever in Nova Scotia.
Cytomegalovirus (CMV) is recognized as an important pathogen in the immuno-suppressed patient. Sporadic case reports of cytomegalovirus community-acquired pneumonia have appeared. We studied 443 patients with community-acquired pneumonia requiring hospitalization to define the role of cytomegalovirus in this illness. Four patients (0.9%) had good evidence that cytomegalovirus caused their pneumonia: 2 had the virus isolated from pulmonary tissue and 2 had cytomegalovirus inclusion bodies visualized in this tissue. An additional 14 patients had serologic evidence (a fourfold rise in the complement fixation tests) of cytomegalovirus infection. Analysis of these 18 patients suggest, that cytomegalovirus plays a role in community-acquired pneumonia. Six (33%) of the patients were immunosuppressed. Six others had concomitant infections: Chlamydia trachomatis (3); Epstein-Barr virus and M. pneumoniae (1); and bacteremia with Group B streptococcus and Bacteroides fragilis plus Eubacterium lentum (1 each). Seven patients (39%) required assisted ventilation, four of whom developed secondary bacterial pneumonia. Five (28%) died. Only two patients had a clinical and radiographic picture suggestive of a viral illness as a cause of the pneumonia. Three patients had atypical lymphocytes in their peripheral blood film. We found that the prevalence of complement fixing antibody to cytomegalovirus increased with age. Such antibody was lacking among those in the 16-20 year group while it peaked at 65% for males and at 78% for females ages 91-100 years. Despite the fact that 42.2% of the adults lacked antibody to cytomegalovirus, community-acquired pneumonia due to this virus is uncommon and does not justify routine serological testing for such infection among patients with community-acquired pneumonia.
The prevalence of Coxiella burnetti infection (Q fever) was determined among Nova Scotia (N.S.) and Prince Edward Island (P.E.I.) blood donors by using the complement fixation and microimmunofluorescence (IF) test. The complement fixation and IF antibody tests measured antibody prevalence for the phase II or phase I and II antigens, respectively. Complement-fixing antibodies to phase II antigen were detected in 4.1% of 997 N.S. and 5.0% of 219 P.E.I. blood donors. Anti-phase II antibodies were detected by microimmunofluorescence in 11.8 and 14.6% of the blood donors in the two provinces, respectively. Anti-phase I antibodies were detected among 2.8% of the N.S. blood donors and 6.3% of the P.E.I. blood donors. Comparison of rates of anti-phase II IF by counties in N.S. revealed that there was at least one county where infection by C. burnetti is hyperendemic. Rates of antibody prevalence were similar in all three areas of P.E.I. examined. We conclude that "Q fever" is endemic in N.S. and P.E.I. and that the microimmunofluorescence test is more suitable than the complement fixation test for seroepidemiologic studies.
The status of the erythrocyte insulin receptor was investigated prior to and during storage at 4C in acid-citrate dextrose (ACD) solution. The receptors on cells that were obtained from both resting and exercised fasting subjects and stored for up to three days in ACD were unchanged as evaluated by both maximal specific hormone binding and the concentration of insulin required to one half maximally inhibit specific binding. These findings indicate, therefore, that the binding of insulin to its receptor on erythrocytes can be assayed in samples of stored blood and that this assay reflects the status of the receptor at the time of sampling.
The activity of eight antimicrobial agents was determined against 115 isolates of Staphylococcus saprophyticus. All were susceptible to ampicillin, cephalexin, and trimethoprim-sulfamethoxazole and resistant to nalidixic acid and novobiocin. A bimodal pattern of susceptibility to erythromycin was observed: 80% were inhibited by 0.25 microgram/ml, whereas 13% required greater than or equal to 128 micrograms/ml. The following urethral staphylococci were susceptible to ampicillin, cephalexin, and nitrofurantoin but resistant to nalidixic acid: S. epidermidis, S. hominis, S. haemolyticus, S. warneri, S. simulans, and S. cohnii.
Our objectives in this study were to elucidate various aspects of the epidemiology of Staphylococcus saprophyticus. This organism was isolated from the midstream urine specimens of 7.5% of 145 college women with frequency and urgency of urination and dysuria, but from only 0.07% of 14,835 urine specimens from adult inpatients at the Victoria General Hospital. It was found to be part of the urethral flora of only 2% of healthy women. Other staphylococci which formed part of the urethral flora of 100 healthy women included S. epidermidis (59 women), S. hominis (15 women), S. haemolyticus (13 women), S. warneri (9 women), and S. aureus (6 women). Finally, we determined that resistance to the 5-micrograms novobiocin disk has a 93% positive predictive accuracy as a presumptive test for S. saprophyticus.
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