Molecular changes in Entamoeba histolytica in response to bacteria

Entamoeba histolytica, the protozoan parasite, is the causative agent of amoebiasis. The degree of virulence, as inferred from invasiveness, of potentially pathogenic strains may be regulated by both host and parasite factors that determine the gut environment. One such factor that plays an important role is the bacterial flora in the gut. Previous studies have clearly shown that bacterial flora is an important determinant of virulence in E. histolytica. However, the exact nature of changes induced in E. histolytica in response to bacteria and their role in virulence is not clear. In this study the levels of a number of molecules potentially important in virulence mechanisms were determined in E. histolytica cells grown with and without normal human bacterial flora, using enzyme-linked immunosorbent assay. Significant changes were observed only after the E. histolytica cells had been adapted to grow with bacterial flora for a number of generations, and not in short term culture.

The economic costs of illicit drug use in Ontario, 1992

The use of illicit drugs causes health and social problems which imply economic costs to society. This paper uses the cost-of-illness method, in particular, the human-capital approach to estimate the prevalence-based economic costs of illicit drug use in Ontario in 1992. This methodology is consistent with international guidelines formulated at the 1994 International Symposium on Economic and Social Costs of Substance Abuse. The economic cost of illicit drug use is estimated at $489.29 million (Canadian dollars) in 1992. Associated with these costs are health-related harms: 211 deaths, half of which occur before the age of 35; and 20 690 days stay in public hospitals.

Interstitial iridium-192 implantation combined with external radiotherapy in anal cancer: ten years experience

PURPOSE

To report our experience in the use of interstitial iridium-192 implantation combined with external radiotherapy in anal cancer.

METHODS AND MATERIALS

From 1984 to 1994, 79 patients with anal cancer were treated with radical intent using radiotherapy (plus chemotherapy) at Beatson Oncology Centre, Glasgow, Scotland. The mean and median age at presentation were 68 and 70 years, respectively (range 34-85) with a male-to-female ratio of 0.39. The histologic distribution was as follows: 48 squamous, 16 basaloid, 14 adenocarcinoma, and 1 basal cell carcinoma. The T stages were: 8 T1, 40 T2, 26 T3, and 5 T4 lesions. Twelve (15%) patients had nodal involvement at presentation. All patients underwent interstitial implantation using iridium-192 as part of the initial treatment. Seventy-six patients were treated with external radiotherapy followed by implant with a mean delay of 37 days after the end of radiotherapy. Twelve patients also received chemotherapy with 5-fluorouracil and mitomycin-C concurrently with external radiotherapy. Follow-up ranged from 6 to 123 months, with a median of 37 months.

RESULTS

Seventy-nine patients were analyzed to assess local control, survival, and complications. A complete response rate of 91% (72 of 79) was achieved after planned radiation treatment. At the end of external radiotherapy, 29% (22 of 76) had achieved complete response, 58% (7 of 12) with chemotherapy and 23% (15 of 64) without it. Local control was achieved in 62 of 79 (78%) patients and 8 of 17 (47%) local failures were salvaged by abdominoperineal resection. Five patients developed inguinal node failure; four of these were salvaged. Overall, 10% of all patients developed distant metastasis as the first site of failure and 25% failed at any site after salvage therapy. Time to unsalvageable relapse was significantly different on comparing T stage (p = 0.005) and histology (p = 0.029) of tumor. Major complications requiring surgical intervention were seen in six (7.5%) patients. Anal function preservation with local control was possible in 56 of 79 (71%) patients.

CONCLUSION

We report excellent results with radiotherapy in T1 and T2 lesions. The role of chemoradiotherapy as radical treatment of anal cancer should be defined in the context of locally advanced tumors.

Health-related quality of life after knee replacement

A cross-sectional, community-based survey of a random sample of 1750 of 242,311 Medicare recipients was performed. The patients were at least sixty-five years old and had had a primary or revision knee replacement (either unilaterally or bilaterally) between 1985 and 1989. Three samples were surveyed separately: a national sample (to reflect the United States as a whole) and samples from Indiana and the western part of Pennsylvania (sites chosen for convenience to assess the validity of the findings for the national sample on a regional level). Each sample was stratified by race, age, residence (urban or rural), and the year of the procedure. Valid and reliable questionnaires were used to elicit the participants' assessments of pain, physical function, and satisfaction two to seven years after the knee replacement. Of the 1486 patients who were eligible for inclusion in the survey, 1193 (80.3 per cent) responded. The mean age of the respondents was 72.6 years. Eight hundred and forty-nine respondents (71.2 per cent) were white, and 849 (71.2 per cent) were women. The participants reported that they had little or no pain in the knee at the time of the survey, regardless of the age at the time of the knee replacement, the body-mass index, or the length of time since the knee replacement. After adjustment for potential confounding variables, predictors of better physical function after the replacement were an absence of problems with the contralateral knee, primary knee replacement (rather than revision) (Indiana sample only), and a lower body-mass index (Indiana and western Pennsylvania samples). Four hundred and fifteen (85.2 per cent) of the 487 patients in the national sample were satisfied with the result of the knee replacement. In what we believe to be the first community-based study of the outcome of knee replacement, patients reported having significant (p = 0.0001) and persistent relief of pain, improved physical function, and satisfaction with the result two to seven years postoperatively. The findings of the present study suggest that age and obesity do not have a negative impact on patient-relevant outcomes (pain and physical function). Dissemination of these findings has the potential to increase appropriate referrals for knee replacement and thereby reduce the pain and functional disability due to osteoarthrosis of the knee.

Clinical trials of nimodipine as a potential neuroprotector in ovarian cancer patients treated with cisplatin

Our previous randomised trial in patients with advanced ovarian cancer indicated a significant response and survival advantage for those receiving high-dose (100 mg/m2) as compared with low-dose (50 mg/m2) cisplatin in combination with cyclophosphamide (750 mg/m2). However, this was accompanied by more toxicity; peripheral neuropathy was troublesome, with 32% of patients experiencing > or = WHO grade 2 at the cisplatin dose of 100 mg/m2. Nimodipine is a calcium-channel antagonist that has provided protection from cisplatin-induced neurotoxicity in a rat model system. We performed a pilot study in 50 patients that demonstrated the feasibility of co-administration of nimodipine in a chronic oral dosing schedule with cisplatin-based chemotherapy in an open-label non-randomised trial. This led us to initiate a double-blind, placebo-controlled, randomised trial in patients with ovarian cancer, which was prematurely discontinued because of problems with nausea and vomiting, leading to poor patient compliance, that were not predicted by the pilot study. These studies did not demonstrate a neuroprotective effect for nimodipine. The primary efficacy variable, i.e, the neurotoxicity score at the end of treatment, gave a significantly lower mean for placebo patients than for nimodipine patients. This report details our experience and discusses the reasons for premature termination of the randomised trial.

Royal Society of Tropical Medicine and Hygiene Meeting at Manson House, London, 12 December 1996. HIV and pneumococcal infection in Africa. Microbiological aspects

By the 1930s several studies had shown that Streptococcus pneumoniae was an important pathogen in Nairobi (Kenya) and various risk factors for infection were recognized, including seasonally cold conditions, overcrowding and recent arrival in the city. Research into pneumococcal disease declined with the arrival of penicillin but recently interest has been rekindled by recognition of the pneumococcus as a human immunodeficiency virus (HIV)-associated pathogen and by the emergence of antibiotic resistance. The pneumococcus and its association with HIV were studied during the course of the Wellcome Trust/Kenya Medical Research Institute HIV Programme in Nairobi (1988-1993). There were generally high rates of pneumococcal disease. The pneumococcus (with tuberculosis and salmonellosis) was a major HIV-related pathogen. One study showed HIV seropositivity to confer a relative risk of 17.8 for pneumococcal infection. Recurrent infection accounted for a large proportion (25%) of disease episodes in a longitudinally studied cohort of HIV patients. There were higher pneumococcal carriage rates in HIV-positive than in HIV-negative patients (28% vs. 16%, P = 0.003). High rates of resistance were found to penicillin (25%). Molecular characterization of penicillin-resistant strains identified 11 separate clones, showing great genetic diversity in a small sample of isolates, and there was evidence of horizontal spread of penicillin-binding protein genes between separate lineages. Molecular characterization of isolates from patients with recurrent disease suggested that both relapse and reinfection might occur. There was molecular evidence of transfer of capsular genes between clones (serotype switching). The overall spectrum of serotypes resembled those reported elsewhere, most serotypes being included in the 23-valent vaccine. Higher numbered serotypes were associated with respiratory tract source and antibiotic resistance. Various methods were used to show 82% concordance between pernasal and blood isolates in pneumonia cases. HIV-seropositive patients were more prone to infection with penicillin- and tetracycline-resistant organisms than seronegative patients (penicillin, 27% vs. 7%; tetracycline, 40% vs. 17%), a difference reflected by different serotype profiles in the 2 groups. These studies highlight the importance of the pneumococcus as an HIV-related pathogen in one part of Africa. The high rates of antibiotic resistance are a cause of concern. There should be continued monitoring of resistance patterns, and assessments of the significance of pneumococcal disease made elsewhere in Africa are to be encouraged.

Caring until the end

As palliative care nurses working in a community based palliative care setting, we have found that patients and their carers (be they non-professional carers, family and/ or friends) have different needs at different times when it comes to information about illness and prognosis.

Actual versus perceived HIV status, sexual behaviors and predictors of unprotected sex among young gay and bisexual men who identify as HIV-negative, HIV-positive and untested

OBJECTIVES

To compare the prevalence and predictors of HIV sexual risk behavior among young gay and bisexual men who perceived themselves to be HIV-negative, HIV-positive, or who were untested.

DESIGN

Population-based sample of young gay and bisexual men.

METHODS

Using multi-stage probability sampling, 408 gay and bisexual men aged 18-29 years in San Francisco were recruited and interviewed, and blood samples for HIV-testing from 364 participants were obtained.

RESULTS

HIV prevalence was 18.7%, although 25% of the men who were HIV-positive did not know it. Thirty-seven per cent reported engaging in unprotected anal intercourse during the past year, including 59% of the men who knew they were HIV-positive, 35% of the men who perceived themselves HIV-negative and 28% of the untested men. Logistic regressions found similar predictors of unprotected intercourse for HIV-negatives and HIV-positives, including sexual impulsivity, substance use, sexual enjoyment and communication problems.

CONCLUSIONS

The high rates of unprotected intercourse, particularly among the HIV-positive men, attest to the urgent need for HIV-prevention interventions for young gay and bisexual men. The findings suggest that many of the important variables to target in interventions are similar for both HIV-positive and HIV-negative men.

[Detection of renal artery stenoses by MRI with surface reconstruction. Value in patients with chronic renal failure]

Forty-three patients with renal artery stenoses were examined with time of flight MR angiography using maximum intensity projection and surface shaded rendering, and with digital substraction angiography. Sensitivity and specificity were 0.83 and 0.78 for main and secondary arteries, 0.87 and 0.84 for main arteries. In azotemic patients, the positive predictive value was estimated at 40%-70% and the negative predictive value at 95%-98%, while the prevalence of renal artery stenoses varied from 10% to 30%. These results validate MRI for the detection of renal artery stenoses in this population. Surface shaded display was more accurate than maximum intensity projection to reconstruct time of flight sequences and to grade renal artery stenoses.

Evaluating an AIDS sexual risk reduction program for young adults in public night schools in São Paulo, Brazil

OBJECTIVES

To describe sexual risk for HIV infection among adult night school students in São Paulo, Brazil, and to evaluate the effect of an HIV/AIDS prevention workshop to reduce sexual risk.

SUBJECTS AND METHODS

A longitudinal study was conducted among four demographically similar public night schools in the inner city of São Paulo. Schools were randomized into intervention and control conditions. Of 394 young adults who took part in the baseline survey, 304 (77%) completed a postintervention questionnaire.

INTERVENTIONS

In a workshop consisting of four sessions of 3 h each, the students discussed AIDS symbolism, the impact of AIDS on their lives, risk perception, the way in which sexual norms shape knowledge and attitudes, AIDS-related knowledge, reproduction and sexual pleasure, and condom use negotiation. We fostered community-building through AIDS training courses for teachers in the schools, peer support programs and public events.

RESULTS

At baseline, 87% had been sexually active at some time and 76% had had sex in the past 6 months. Among those who reported vaginal intercourse and/or anal intercourse, condom use was low. The workshops were positively process-evaluated and supported by the community, the students, their teachers and their parents. We obtained statistically significant effects from the workshops for females only, who reported improved communication with partners about sex and AIDS and less unprotected sex with non-monogamous partners after the intervention.

CONCLUSION

These data show that the sexual risk of HIV infection can be lowered when Brazilian disenfranchized communities support AIDS prevention workshops. Even more impressive results may be achieved if the need to address socioeconomic obstacles and gendered sexual roles is emphasized through further long-term community development programs.

Mandible muscle fibers in ants: fast or powerful?

Ants use their mandibles for catching prey, cracking seeds, cutting leaves, or for the construction of nests and the tender care of brood. The functional morphology of the mandibles reflect the species' adaptations to particular foraging habits and social life. The versatility and specialization of the mandibles depend directly on the design and physiology of the mandible closer muscles and their component fibers. A comparative video analysis of the closing movements of ant mandibles revealed that the maximal velocity varies considerably among species. The speed is correlated with the morphology of the mandible closer muscle, the largest muscle in ants. It is composed of two morphologically very distinct fiber types: long fibers with short sarcomeres (sarcomere length approximately 2 microM) showing all the structural attributes of fast muscle fibers, and shorter fibers with longer sarcomeres (sarcomere length approximately 5 microM) exhibiting the characteristics of slow and powerful fibers. Ants with fast-moving mandibles have a very high proportion of fast closer fibers, whereas the muscles of ants that cannot perform fast mandible movements have only a few or no fast fibers at all. Fast fibers always attach directly to the solid apodeme, while slow fibers often attach to thin apodeme threads. We suppose that the latter kind of fiber attachment is disadvantageous for fast contracting fibers but helps the ants to make better use of the space in the head capsule.

Recent transmission of tuberculosis in a cohort of HIV-1-infected female sex workers in Nairobi, Kenya

OBJECTIVES

To describe the epidemiological and clinical characteristics of HIV-related tuberculosis in a female cohort, and to investigate the relative importance of recently transmitted infection and reactivation in the pathogenesis of adult HIV-related tuberculosis.

DESIGN

Members of an established cohort of female sex workers in Nairobi were enrolled in a prospective study. Women were followed up regularly and seen on demand when sick.

METHODS

Between October 1989 and September 1992 we followed 587 HIV-infected and 132 HIV-seronegative women. Standard protocols were used to investigate common presentations. Cases of tuberculosis were identified clinically or by culture. All available Mycobacterium tuberculosis strains underwent DNA fingerprint analysis.

RESULTS

Forty-nine incident and four recurrent episodes of tuberculosis were seen in HIV-infected women; no disease was seen in seronegative sex workers (P = 0.0003). The overall incidence rate of tuberculosis was 34.5 per 1000 person-years amongst HIV-infected participants. In purified protein derivative (PPD) skin test-positive women the rate was 66.7 per 1000 person-years versus 18.1 per 1000 person-years in PPD-negative women. Twenty incident cases (41%) were clinically compatible with primary disease. DNA fingerprint analysis of strains from 32 incident cases identified two clusters comprising two and nine patients; allowing for index cases, 10 patients (28%) may have had recently transmitted disease. Three out of 10 (30%) patients who were initially PPD skin test-negative became PPD-positive. Taken together, 26 incident cases (53%) may have been recently infected. DNA fingerprint analysis also identified two (50%) of the four recurrent tuberculosis episodes as reinfection.

CONCLUSIONS

Substantial recent transmission of tuberculosis appears to be occurring in Nairobi amongst HIV-infected sex workers. It may be incorrect to assume in other regions of high tuberculosis transmission that active HIV-related tuberculosis usually represents reactivation of latent infection.

Automatic stenosis detection and quantification in renal arteriography

Visual assessment of the degree of renal artery stenosis on renal arteriography has a large inter- and intraobserver variability. This degree is usually estimated by the ratio between the most narrowed portion of the artery and the reference diameter. The latter is a priori unknown information and thus operator dependent. The objective of the present work was to test the performances of a computer system that was designed to analyze and quantify lesions on 2D renal arteriograms. The main hypothesis was to consider that the most frequent diameter computed along the artery was a good candidate to approximate the reference diameter. Forty nine patient images were collected from the EMMA randomized trial, a multicenter study comparing two treatment strategies in unilateral atheromatous renal artery stenosis of at least 60%. For each image, the degree of stenosis was evaluated by five independent experts and the mean value was used to represent the gold standard for the computer system. The system is based on a fuzzy automaton and performs a syntactic analysis of the arterial segment providing automatic and reproducible quantification of lesions. Both the radiologist caring for the patient and the system were compared to the gold standard. Compared to individual radiologists, the computer system gave a more precise estimation of percent stenosis and did not over or under estimate the severity of the lesion.

Differences in sexual behavior among HIV discordant and concordant gay men in primary relationships

We investigated differences in unprotected anal intercourse among gay men in HIV concordant and discordant primary relationships. Individuals were recruited in 1992 from household- and bar-based samples of gay/bisexual men in Portland, Oregon, and Tucson, Arizona. Respondents were men who reported that they were in primary relationships of > or = 1 month and who reported their own and their partner's HIV status (n = 785). Comparisons were made between three groups: (a) HIV + respondents/HIV + partners; (b) HIV- respondents/HIV- partners; and (c) respondents whose partner's HIV status was different from their own (discordant), on sexual behavior, psychosocial, and demographic variables. Men in HIV concordant relationships reported significantly higher rates of unprotected anal intercourse (54% for +2 and 48% for --) than discordant couples (17%). HIV- men in concordant relationships were more likely to be monogamous (58%) and younger (22% < or = 25 years) than the other two groups. There were no significant differences among the groups regarding the kind of sexual behaviors they engaged in with nonprimary partners. The substantially lower rate of unprotected anal intercourse among men in discordant relationships compared to men in concordant relationships suggests that individuals and couples make judgments about sex and behavior based on knowledge of one's own and one's partner's HIV status.

Applying the marketing concept in health care: the no-show problem

This article applies the marketing concept to the no-show problem in health care. The no-show problem at a hospital-based outpatient internal medicine clinic was analyzed to determine the determinants of no-show behavior. Two surveys were conducted: a patient questionnaire, and a telephone interview of patients that had recently missed an appointment. The surveys identified the lack of transportation as an important determinant of no-show behavior among the clinic's low-income and elderly patient population. The authors suggest that effective implementation of the marketing concept requires that health care organizations offer individualized transportation services to and from their facilities.

Identification of novel genes from Entamoeba histolytica by expressed sequence tag analysis

Shotgun sequencing of cDNA clones is now an established approach to gain insight into the expressed nucleotide (nt) sequences in a given cell. We analysed 100 randomly picked cDNA clones of the protozoan parasite, Entamoeba histolytica, by nt sequencing, with a view to obtain novel gene sequences not detected so far by biochemical and genetic analyses. About 56% of the analysed clones showed significant homology with other genes in the database, including a number of genes whose presence may not be suspected in E. histolytica owing to its unusual subcellular organization. The results suggest that this approach can provide important clues to understand unique biochemical mechanisms in this parasite.

Phaeohyphomycosis caused by Exophiala dermatitidis following intra-articular steroid injection

A patient with long-standing rheumatoid arthritis presented with a painful pigmented chronic nodule on the dorsum of the right hand, at the site of intra-articular steroid injections undertaken 5 years previously. Histology showed pigmented fungal elements consistent with phaeohyphomycosis. Cultures yielded black yeast-like colonies, identified as Exophiala dermatitidis and sensitive to itraconazole and amphotericin. A 1-month course of itraconazole resulted in marked clinical improvement but surgical excision and skin grafting were required for complete resolution. Phaeohyphomycosis has been related to inoculation injury but association with intra-articular steroid injection appears hitherto to be unreported.

Tuberculosis in Siberia: 2. Diagnosis, chemoprophylaxis and treatment

OBJECTIVE

To assess tuberculosis diagnosis, chemoprophylaxis and therapy in Siberia as a paradigm for the Russian Federation.

DESIGN

Data was obtained from official sources and through visits to dispensaries and hospitals in 1994.

RESULTS

Tuberculosis disease and cure is classified according to a Dispensary Group Register based principally on clinical and radiological criteria. Isoniazid is widely used for chemoprophylaxis and post-therapy and may be linked to high levels of isoniazid resistance. Combination drug therapy is individualized, frequently changed, and given orally, parenterally or intra-bronchially. Galvanization, autotransfusion of ultra-violet irradiated blood, antioxidants and steroids are used as adjunct treatment. Ambulatory treatment is uncommon. Surgical treatments including lobectomy and pneumonectomy are used in 5-10% of patients.

CONCLUSION

Tuberculosis is increasing in Siberia. An improved drug supply using short course standardized regimens is required supported by high quality co-ordinated bacteriological services. Surgery retains a useful role, but many adjunct therapies should be abandoned.