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Biomedical subjects

N Low

Publications and source records attributed to N Low.

53 records · Page 3Linked to original sources
PubMed1996

Spectrum of disease in Africans with AIDS in London.

OBJECTIVE: To compare the spectrum of disease, severity of immune deficiency and chemoprophylaxis prescribed in HIV-infected African and non-African patients in London. DESIGN: Retrospective review of case notes of all HIV-infected Africans and a comparison group of non-Africans attending 11 specialist HIV/AIDS Units in London. MAIN OUTCOME MEASURES: Comparison of demographic information, first and subsequent AIDS-defining conditions, levels of immune deficiency, and chemoprophylactic practices between the African and non-African groups. RESULTS: A total of 1056 Africans (313 developing AIDS) and 992 non-Africans (314 developing AIDS) were studied. Africans presented later than non-Africans (median CD4+ lymphocyte counts at diagnosis 238 and 371 x 10(6)/l, respectively). Tuberculosis accounted for 27% of initial episodes of AIDS in Africans and 5% in non-Africans; Pneumocystis carinii pneumonia (PCP) was the initial AIDS-defining condition in 34% of non-Africans and 17% of Africans. The incidence of tuberculosis in Africans with another AIDS-indicator disease was 16 per 100 person-years. PCP prophylaxis was prescribed for 40% Africans and 32% non-Africans; only 8% of Africans received tuberculosis preventive therapy. CONCLUSIONS: HIV-infected African patients presented at lower levels of CD4+ lymphocyte count, at a more advanced clinical stage, and with different AIDS-indicator diseases as compared with non-Africans. Prophylaxis against tuberculosis should be considered for all HIV-infected African patients in industrialized countries. The high incidence of diseases that are indicative of advanced immunodeficiency (e.g., cytomegalovirus disease) in African patients contrasts with data from Africa, suggesting better survival chances in the UK.

Acquired Immunodeficiency Syndrome↗
PubMed1996

AIDS survival and progression in black Africans living in south London, 1986-1994.

OBJECTIVES: To describe the rate of progression to AIDS and survival following AIDS diagnosis in HIV-infected Africans living in London. To identify factors influencing progression and outcome of disease. DESIGN: Retrospectively constructed prevalent cohort. SETTING: Outpatient clinic population, London. SUBJECTS: HIV-infected individuals of African origin presenting between January 1986 and October 1994. MAIN OUTCOME MEASURES: AIDS indicator illness; cumulative survival probabilities to AIDS diagnosis and from AIDS diagnosis to death; rate of progression to AIDS. RESULTS: Ninety six patients (57 women) provided 166 person years of follow up. Median CD4 lymphocyte count at presentation was 205 (90% range 20-577) x 10(6)/l. Kaplan-Meier estimates of the proportion (95% confidence interval) of patients developing AIDS from the time of enrollment were 18 (9 to 27)% at 12 months and 44 (30 to 58)% at 36 months. Only CD4 count at HIV diagnosis was independently associated with a faster rate of progression to AIDS (adjusted relative hazard 9.18%, 95% confidence interval 2.84 to 29.67, p < 0.001). The proportion (95% confidence interval) surviving following AIDS diagnosis was estimated to be 73 (55 to 91)% at 12 months and 25 (0 to 52)% at 36 months. CONCLUSIONS: HIV-infected people of sub-Saharan African origin living in London present with advanced disease. When compared with published studies, their survival experience is comparable to that observed in HIV-infected individuals born in developed countries.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Neuropsychological deficits in tests of executive function in asymptomatic and symptomatic HIV-1 seropositive men.

There has been much debate about the exact nature and time of onset of the cognitive impairments associated with infection by the human immunodeficiency virus type 1 (HIV-1). Studies to date have not reached consistent conclusions. The present study comprised 22 asymptomatic and 18 symptomatic HIV-1 seropositive men, whose only risk factor for contraction of the virus was sexual intercourse, and 18 seronegative controls matched for age and IQ. Subjects were given computerized neuropsychological tests from the CANTAB battery, which assessed visuospatial memory, attention and executive function. Both the asymptomatic and the symptomatic HIV-1 seropositive subjects showed a selective pattern of deficits relative to the controls. In addition, the seropositive subjects were subtly but significantly impaired on tests of executive function but unimpaired on certain tests of visual memory. This finding supports an hypothesis that frontostriatal dysfunction occurs in HIV-1 infected individuals prior even to the expression of clinical symptoms.

Adult↗
PubMed1993

Acute toxicity during external-beam radiotherapy for localized prostate cancer: comparison of different techniques.

PURPOSE: The chronic and acute toxicities associated with conventional radiotherapy of localized prostate cancer are well documented. However, the degree and incidence of toxicities with conformal techniques are not known. Studying side effects associated with modern radiotherapeutic techniques is more important now since there has been a general trend to use computerized tomography-based techniques in recent years; beam's eye view-based conformal techniques are also becoming more commonplace. It is possible that the local disease control can be improved with the delivery of higher doses than currently used. Conformation of the treatment volume to the target volume may facilitate such dose-escalation. However, prior to such dose-escalation, it is important to know the toxicities associated with such techniques with conventional doses. METHODS AND MATERIALS: We have compared week-by-week acute toxicities associated with conventional (Group A, 16 patients), computerized tomography-based, manual (Group B, 57 patients) and beam's eye view-based (Group C, 43 patients) techniques during 7 weeks of radiotherapy. Group B and C patients were treated contemporaneously (1988-1990). RESULTS: Acute side effects gradually increased from week 1 through weeks 4-5 and generally declined or plateaued after that. The incidence of acute toxicities was significantly less with the beam's eye view/based technique than with the other two methods. For instance, the percentages of Grade 2 acute genitourinary toxicities for Groups A, B, and C were as follows: Week 1-0, 0, 0; Week 2-6, 0, 0; Week 3-6, 9, 2; Week 4-12, 14, 9; Week 5-35, 14, 9; Week 6-31, 16, 7; Week 7-33, 8, 8, respectively. The p values associated with differences in acute genitourinary toxicities for Weeks 1-7 using chi-square test were 0.072, 0.627, 0.389, 0.538, 0.123, 0.06, and 0.012; the p values for acute gastrointestinal toxicities were 0.512, 0.09, 0.031, 0.031, 0.003, < 0.0001, and 0.004, respectively. Pairwise comparison (Wilcoxon rank-sum test) showed statistically significant lower acute toxicity in Group C than Group B (e.g., p values, Weeks 1-7 for gastrointestinal toxicity: 0.633, 0.056, 0.010, 0.014, < 0.0001, < 0.0001, and < 0.0001, respectively) in the latter part of the treatment course. No correlation was found between the extent of toxicity and the patient age or the overall treatment time. Also, no correlation was found between the degree of toxicity and the radiation dose and fraction size, within the narrow ranges used (65-70 Gy and 180-200 cGy, respectively). A trend suggesting increased severity of toxicity with increase in the volume of treatment was seen. CONCLUSION: The findings in this retrospective study need to be confirmed by other prospective studies.

Acute Disease↗
PubMed1993

How many people actually use condoms? An investigation of motel clients in Managua.

Motels in Nicaragua are popular venues for both commercial and non-commercial sexual encounters and thus provide a potential location for the spread of sexually transmitted agents, including the human immunodeficiency virus. Condoms are known to be effective barriers against these infections, but are infrequently used by Nicaraguans. We interviewed all motel owners in one district of Managua and in five randomly selected motels ascertained, by retrieval and inspection, actual rates of condom use by clients. Six out of 26 establishments initially supplied condoms: when provided on entry to the motel condoms were used in 37% of observed encounters. Condom use can be assessed objectively in certain circumstances and this method can provide a reliable outcome measure for condom promotion programmes.

Condoms↗
PubMed1993

AIDS in Nicaragua: epidemiological, political, and sociocultural perspectives.

The AIDS epidemic in Nicaragua is several years behind that in the United States and neighboring countries of Central and South America. A combination of events, including the isolation caused by the war of the U.S.-backed Contra army against the Sandinista government, the complete economic embargo imposed on Nicaragua by the United States in 1985, self-sufficiency for blood products, and a low rate of recreational injectable-drug use, have contributed to this situation. Since the Sandinistas were defeated in the general election of 1990, people have returned to Nicaragua from areas where HIV is more prevalent, such as Honduras and the United States. It is probable that many HIV-infected persons have now entered the country. Because of the high rates of sexually transmitted diseases and cultural factors such as "machismo," HIV is likely to spread rapidly by heterosexual transmission, unless effective, culturally appropriate education and sexually transmitted disease prevention programs are implemented now.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Practical applications of Beam's Eye View-based treatment planning to head and neck sites.

Because of the complex anatomy of the structures involved by tumor as well as of the critical normal structures, treatment planning for advanced or spatially irregular cancers of head and neck sites is often extremely challenging. Computerized axial tomographic scanning is frequently invaluable in delineating tumor extension into areas inaccessible to physical examination. Our Beam's Eye View Planning (BEVP) capability allows us to incorporate this radiographic information accurately into actual plans used in the clinic. Over the past 2 1/2 years, we have applied this technique to 31 selected head and neck cancer patients at Michael Reese/University of Chicago Center for Radiation Therapy. Tumors were chosen on the basis of anatomical complexity: most involved multiple head and neck sites including orbit, skull base, paranasal sinuses and cavernous sinus. In all cases, radiation tolerance of critical normal structures including spinal cord, brain stem, optic chiasm, and eye had to be considered. With careful use of rigid immobilization devices and the outlining of several normal structures for purposes of alignment, we had no difficulty applying our BEVP technique to clinical simulations. Oblique field blocking was especially facilitated by BEVP. We found the BEVP technique very useful to assure that tumor coverage was adequate and tolerance of normal tissues not exceeded.

Computer Simulation↗
PubMed1992

[Concepts about AIDS among the adult population of Managua].

Nicaragua has the lowest prevalence of AIDS in Central America. In other countries where AIDS is more prevalent, the first epidemic of asymptomatic infections with human immunodeficiency virus (HIV) and the second of clinical cases of AIDS have been followed by a third epidemic of fear and discrimination. In December 1989 a study was conducted to investigate knowledge and attitudes about AIDS in a sample of 287 adults in Managua. Most of the interviewees had heard of the disease from newspapers and television, and more than 90% understood how HIV was principally transmitted. However, between one-third and one-half the interviewees believed that HIV could be transmitted by causal contact such as kissing (53%) or by mosquito bites (49%). In addition, the majority considered that isolation of HIV-infected persons and control of immigration into the country would be effective measures for preventing the spread of the disease. These results are similar to findings from studies carried out in other countries of Latin America where the HIV and AIDS epidemics started much earlier. This would suggest that the so-called "third epidemic" of discrimination and fear is affecting Nicaragua in advance of the other two.

Acquired Immunodeficiency Syndrome↗
PubMed1991

AIDS in Nicaragua.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Beams eye view-based photon radiotherapy I.

Geographic miss, dosimetric miss (underdosing), and proximity of the tumor to sensitive normal tissues are some of the causes of inadequate radiation dose delivery; this is one of many causes of failure after radiotherapy. In the past decade, computerized tomography (CT)-based treatment planning has helped to overcome some of these problems. Beam's eye view (BEV)-based radiotherapy planning is an improvement over CT-based treatment planning that may further increase the therapeutic ratio. Since January 1988, we have treated 198 patients with BEV-based photon radiotherapy. About 40% of our patients treated with radical radiotherapy undergo BEV-based treatment, and about 70% of patients who undergo planning CT in the treatment position receive BEV-based radiotherapy. Our findings are as follows: (a) routine use of BEV-based RT (BEVRT) is possible in a busy radiation oncology department; (b) BEVRT improves geometric coverage of tumors; (c) BEVRT is extremely useful in the design of oblique portals; (d) time commitments for various members of the RT treatment-planning team are reasonable; (e) BEVRT helps individualize RT technique; (f) preliminary data suggest decreased acute toxicity with the use of BEVRT for prostate cancer patients. Whether these advantages will help to improve the outcome (i.e., improve local control and survival) and/or decrease the long-term toxicity is not yet known.

Breast Neoplasms↗
PubMed1991

Optimization of radical radiotherapy with beam's eye view techniques for non-small cell lung cancer.

The presence of vital and sensitive organs such as the spinal cord, heart, and lungs makes curative radiotherapy of non-small cell lung cancer difficult to implement and necessitates use of oblique portals. Defining the target volumes in oblique portals is very difficult. We now show, for non-small cell lung cancer, how beam's eye view-based radiotherapy can be used for accurate delineation of treatment volumes and for avoidance of real or dosimetric geographic misses. Furthermore, the beam's eye view-based method enables one to project accurately a 2-dimensional image of 3-dimensional disease extension, especially in oblique fields, thus facilitating the design of accurate customized blocking and avoiding inadvertent blocking of the tumor or unnecessary irradiation of normal tissues. Beam's eye view volumetric analysis is helpful for devising a customized treatment plan for each patient. Such customization may minimize local failure, which is one cause of poor results of radiotherapy in this site. Beam's eye view-based radiotherapy has the potential of improving local control and hence may improve the survival of patients with non-small-cell lung cancer.

Carcinoma, Non-Small-Cell Lung↗
PubMed1981

Neoplastic angioendotheliosis: a clinicopathological entity with multifocal presentation. Case report.

Neoplastic angioendotheliosis is a rare disorder characterized by intravascular neoplastic proliferation of endothelial cells within vessels of all caliber in the meninges and neuropil. Ischemic infarcts of brain and spinal cord result from occlusion of the lumina by neoplastic cells of fibrin thrombi. Transition from reactive to neoplastic endothelium can be identified in many vessels. Steroid therapy can be beneficial in reduction of severity of symptoms, but cannot alter the course of disease. Therapeutic intervention must be undertaken promptly after the diagnosis is confirmed by meningeal and cortical biopsy if the inexorable course of the disease is to be altered.

Adult↗