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Biomedical subjects

Sebastian Lucas

Publications and source records attributed to Sebastian Lucas.

11 recordsLinked to original sources
PubMed2006

Contiguous spread of Mycobacterium ulcerans in Buruli ulcer lesions analysed by histopathology and real-time PCR quantification of mycobacterial DNA.

The distribution of M. ulcerans in Buruli ulcer lesions was analysed by IS2404 real-time PCR quantification of M. ulcerans DNA and by semi-quantitative microscopic assessment of the number of acid-fast bacilli (AFB). Mycobacterial burden was compared with histopathological changes. Focal distribution of tissue destruction extending into areas with high and low mycobacterial burden was a feature in all lesions analysed. Even where most of the mycobacteria were washed out of ulcerative lesions, peaks of mycobacterial DNA and AFB in the necrotic base of the ulcers still marked the position of the primary infection focus. Significant amounts of mycobacterial DNA and microcolonies were also present in samples from more peripheral regions and occasionally in excised margins of macroscopically and histologically healthy-appearing excised tissue margins. Additional peaks of mycobacterial DNA clearly marked sites where satellite lesions were developing. Even when granulomas provided evidence for the development of cell-mediated immunity, development of satellite lesions by contiguous spreading was not completely prevented. Areas free of mycobacterial DNA were found between primary and secondary infection foci and around scarring tissue of healing lesions. These results demonstrate that IS2404 real-time PCR analysis is a better tool than the less sensitive and only semi-quantitative microscopic enumeration of AFB for studying the dynamics of M. ulcerans infection in situ.

Adult↗
PubMed2004

Cerebral CD8+ lymphocytosis in HIV-1 infected patients with immune restoration induced by HAART.

In HIV infected persons, highly active antiretroviral therapy (HAART) has reduced both the morbidity and incidence of several disorders. Its effects on direct HIV-induced damage to the CNS remain controversial. In addition, HAART may provoke an "immune reconstitution inflammatory syndrome" (IRIS). Herein we report two patients who, despite HAART, developed a diffuse encephalopathy. Their clinical, radiological and neuropathological features are described. Immunohistochemical and PCR analyses were used to detect HIV and to exclude other viruses in brain tissue. The unusual inflammatory reaction in the brain tissue was defined by immunohistochemistry. Both patients had advanced HIV disease with low CD4 counts and high HIV "viral loads" before starting HAART. In both, HAART induced an increase in CD4 count and a marked reduction in HIV viral load, which was accompanied, in patient one, by worsening of pre-existing, and, in patient two, by development of, acute encephalopathy. At post-mortem examination, the brain of patient one showed HIV encephalitis. In addition, the brains of both patients revealed HIV-DNA by PCR, diffuse microglial hyperplasia and massive and diffuse perivascular and intraparenchymal infiltration by CD8+/CD4- lymphocytes. We suggest that the rapid immune reconstitution induced by HAART in these two patients led to a redistribution of lymphocytes into peripheral blood. This was followed by recruitment of CD8+ lymphocytes into the brain, which resulted in the diffuse infiltration described. The appearances in patient two further suggest that HIV brain infection, even without encephalitis, is sufficient to trigger this response.

Adult↗
PubMed2003

Leprosy affects facial nerves in a scattered distribution from the main trunk to all peripheral branches and neurolysis improves muscle function of the face.

Current literature rejects nerve release in leprous facial neuropathy and states that lesions are restricted to the peripheral zygomatic branches. Since there are approximately 500,000 patients with this disease throughout the world, we wanted to clarify the precise location of facial nerve's affection and the benefit of neurolysis. Our study showed that in patients with leprosy, the facial nerve's main trunk, the peripheral zygomatic branches, and all other branches were affected. Follow-up showed improvement in lagophthalmos and in misreinnervation, with no improvement in the control cohort. Nerve release improves muscle function in leprous facial neuropathy, provided surgery is performed on all affected segments. Intraoperative electroneurodiagnostics is an effective tool for detecting the most proximal site of lesion and ensuring effective surgery.

Adult↗
PubMed2002

Lung diseases at necropsy in African children dying from respiratory illnesses: a descriptive necropsy study.

BACKGROUND: Accurate information about specific causes of death in African children dying of respiratory illnesses is scarce, and can only be obtained by autopsy. We undertook a study of children who died from respiratory diseases at University Teaching Hospital, Lusaka, Zambia. METHODS: 137 boys (93 HIV-1-positive, 44 HIV-1-negative], and 127 girls (87 HIV-1-positive, 40 HIV-1-negative) aged between 1 month and younger than 16 years underwent autopsy restricted to the chest cavity. Outcome measures were specific lung diseases, stratified by age and HIV-1 status. FINDINGS: The presence of multiple diseases was common. Acute pyogenic pneumonia (population-adjusted prevalence 39.1%, 116/264), Pneumocystis carinii pneumonia (27.5%, 58/264), tuberculosis (18.8%, 54/264), and cytomegalovirus infection (CMV, 20.2%, 43/264) were the four most common findings overall. The three most frequent findings in the HIV-1-negative group were acute pyogenic pneumonia (50%), tuberculosis (26%), and interstitial pneumonitis (18%); and in the HIV-1-positive group were acute pyogenic pneumonia (41%), P carinii pneumonia (29%), and CMV (22%). HIV-1-positive children more frequently had P carinii pneumonia (odds ratio 5.28, 95% CI 2.12-15.68, p=0.0001), CMV (7.71, 2.33-40.0, p=0.0002), and shock lung (4.15, 1.20-22.10, p=0.03) than did HIV-1-negative children. 51/58 (88%) cases of P carinii pneumonia were in children younger than 12 months, and five in children aged over 24 months. Tuberculosis was common in all age groups, irrespective of HIV-1 status. INTERPRETATION: Most children dying from respiratory diseases have preventable or treatable infectious illnesses. The presence of multiple diseases might make diagnosis difficult. WHO recommendations should therefore be updated with mention of HIV-1-positive children. Improved diagnostic tests for bacterial pathogens, tuberculosis, and P carinii pneumonia are urgently needed.

Adolescent↗
PubMed2002

Identification of Pneumocystis carinii DNA in oropharyngeal mouth washes from AIDS children dying of respiratory illnesses.

Polymerase chain reaction (PCR) using Pneumocystis carinii-specific primers pAZ 102-H(5'-GTGTACGTTGCAAAGTACTC-3') and pAZ 102-E(5'-GATGGCTGTTTCCAAGCCCA-3') was performed on oropharyngeal washes obtained at autopsy from 22 AIDS children with histologically confirmed P. carinii pneumonia (PCP), and 48 control AIDS children who died from other infections. Fifteen of 22 (68%) PCP samples and none of 48 (0%) control samples had detectable P. carinii DNA (sensitivity 68%; specificity 100%; positive predictive value 100%; negative predictive value 87%). This method requires further validation in clinical practice.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Identification of Pneumocystis carinii DNA by polymerase chain reaction in necropsy lung samples from children dying of respiratory tract illnesses.

Polymerase chain reaction for Pneumocystis carinii DNA was performed on necropsy lung samples from children by means of P carinii -specific primers.P carinii DNA was identified in 22 of 22 (100%) samples with histologically proven P carinii pneumonia and 13 of 75 (17%) with non-P carinii pneumonia respiratory illness (sensitivity, 100%; specificity, 83%). The low specificity precludes the use of polymerase chain reaction as an alternative to histopathologic diagnosis.

Autopsy↗
PubMed2002

The pathology of HIV infection.

The acquired immunodeficiency syndrome (AIDS) is the result of a human immunodeficiency virus (HIV) infection damaging the cell-mediated immune system. A wide range of opportunistic infections (OI) and tumours develop; additionally, HIV directly damages some organs. The patterns of opportunistic diseases (OD) are different in different parts of the world, depending on the local prevalence of latent and acquired infections and on the survival of HIV-infected patients. OD patterns change as people migrate. Recently introduced highly active anti-retroviral chemotherapy prevents many of the common OIs, but also introduces a new range of toxic pathological damage. Longer survival permits development of new HIV-related diseases. The pathology of HIV/AIDS is not static but changing.

AIDS-Related Opportunistic Infections↗