Droplets, dust and guinea pigs: an historical review of tuberculosis transmission research, 1878-1940.

The transmission of tuberculosis (TB) occurs mainly via inhalation of airborne droplet nuclei; however, the precise details of this process remain uncertain. We reviewed the literature from 1870 to 1940, when Mycobacterium tuberculosis was discovered and the concept of transmission emerged as a hallmark of the infectious disease. By 1940, laboratory experiments, animal studies and clinical observation had demonstrated that cough was central to TB transmission, and that guinea pigs close to patients with cough could be infected, mainly by patients coughing small droplets likely containing only 1-2 bacilli. A minority of pulmonary TB patients, usually during the early stages of the disease, with thin watery sputum, more successfully coughed small infectious droplets than patients with heavily smear-positive tenacious sputum who were often too ill and too weak to cough vigorously. There was ongoing debate regarding the possible importance of desiccated sputum particles found in surface dust. Investigation of TB transmission has a history of more than 130 years.

Perspectives for personalized therapy for patients with multidrug-resistant tuberculosis.

According to the World Health Organization (WHO), tuberculosis is the leading cause of death attributed to a single microbial pathogen worldwide. In addition to the large number of patients affected by tuberculosis, the emergence of Mycobacterium tuberculosis drug-resistance is complicating tuberculosis control in many high-burden countries. During the past 5 years, the global number of patients identified with multidrug-resistant tuberculosis (MDR-TB), defined as bacillary resistance at least against rifampicin and isoniazid, the two most active drugs in a treatment regimen, has increased by more than 20% annually. Today we experience a historical peak in the number of patients affected by MDR-TB. The management of MDR-TB is characterized by delayed diagnosis, uncertainty of the extent of bacillary drug-resistance, imprecise standardized drug regimens and dosages, very long duration of therapy and high frequency of adverse events which all translate into a poor prognosis for many of the affected patients. Major scientific and technological advances in recent years provide new perspectives through treatment regimens tailor-made to individual needs. Where available, such personalized treatment has major implications on the treatment outcomes of patients with MDR-TB. The challenge now is to bring these adances to those patients that need them most.

HIV testing uptake among the household contacts of multidrug-resistant tuberculosis index cases in eight countries.

SETTING: The household contacts (HHCs) of multidrug-resistant tuberculosis (MDR-TB) index cases are at high risk of tuberculous infection and disease progression, particularly if infected with the human immunodeficiency virus (HIV). HIV testing is important for risk assessment and clinical management. METHODS: This was a cross-sectional, multi-country study of adult MDR-TB index cases and HHCs. All adult and child HHCs were offered HIV testing if never tested or if HIV-negative >1 year previously when last tested. We measured HIV testing uptake and used logistic regression to evaluate predictors. RESULTS: A total of 1007 HHCs of 284 index cases were enrolled in eight countries. HIV status was known at enrolment for 226 (22%) HHCs; 39 (4%) were HIV-positive. HIV testing was offered to 769 (98%) of the 781 remaining HHCs; 544 (71%) agreed to testing. Of 535 who were actually tested, 26 (5%) were HIV-infected. HIV testing uptake varied by site (median 86%, range 0-100%; P < 0.0001), and was lower in children aged <18 years than in adults (59% vs. 78%; adjusted for site P < 0.0001). CONCLUSIONS: HIV testing of HHCs of MDR-TB index cases is feasible and high-yield, with 5% testing positive. Reasons for low test uptake among children and at specific sites-including sites with high HIV prevalence-require further study to ensure all persons at risk for HIV are aware of their status.

Direct comparison of liquid-based and smear-based cytology with and without rapid on-site evaluation for fine needle aspirates of thoracic tumors.

BACKGROUND: Liquid-based cytology (LBC) and rapid on-site evaluation (ROSE) are proposed to improve the quality of fine needle aspirates (FNA) and their diagnostic yield compared with conventional smear cytology (CSC). This prospective study directly compared outcomes of sonar-guided FNA of thoracic tumors supported by LBC, CSC, or CSC with ROSE. METHODS: Three aspirates each for both LBC and CSC with separate 22G spinal needles in a randomized, alternating sequence during 64 transthoracic FNA of thoracic tumors were collected. Smears were prepared by cytology staff on site but evaluated with ROSE only when all six samples had been collected. If no diagnostic material was found on the first three CSC additional needle passes guided by ROSE were performed. RESULTS: Final diagnoses were non-small cell lung cancer in 50 (78.1%), small cell lung cancer in 11 (17.2%), mesothelioma in 1 (1.6%), and inflammation in 2 cases (3.1%), respectively. LBC and CSC were diagnostic in 42 (65.6%) and 49 (76.6%) cases, respectively (P = 0.039), with both methods diagnostic in 41 cases (64.1%). Fifteen cases (23.4%) remained undiagnosed following three passes for CSC but 9 (14.1%) of these were diagnosed using FNA and ROSE with a total yield of 58 cases (90.6%; P < 0.001). CONCLUSION: The diagnostic yield of transthoracic FNA submitted for LBC is significantly lower than with CSC when slides are prepared professionally. ROSE significantly increases the yield of transthoracic FNA.

The diagnostic accuracy of integrated positron emission tomography/computed tomography in the evaluation of pulmonary mass lesions in a tuberculosis-endemic area.

BACKGROUND: Integrated positron emission tomography/computed tomography (PET-CT) is a well-validated modality for assessing pulmonary mass lesions and specifically for estimating risk of malignancy. Tuberculosis (TB) is known to cause false-positive PET-CT findings. OBJECTIVE: To investigate the utility of PET-CT in the evaluation of pulmonary mass lesions and nodules in a high TB prevalence setting. METHODS: All patients referred for the evaluation of a solitary pulmonary nodule or mass and who underwent PET-CT scanning over a 3-year period were included. The PET-CT findings, including maximum standardised uptake value (SUVmax), were compared with the gold standard (tissue or microbiological diagnosis). The sensitivity, specificity, positive and negative predictive values and diagnostic accuracy for malignant disease were calculated according to the SUVmax cut-off of 2.5 and a proposed cut-off obtained from a receiver operating characteristic (ROC) curve. RESULTS: Forty-nine patients (mean (standard deviation) age 60.1 (10.2) years; 29 males) were included, of whom 30 had malignancy. Using an SUVmax cut-off of 2.5, PET-CT had a sensitivity, specificity, positive and negative predictive value and diagnostic accuracy for malignancy of 93.3%, 36.8%, 70.0%, 77.8% and 71.4%, respectively. After a ROC curve analysis, a suggested SUVmax cut-off of 5.0 improved the specificity to 78.9% and the diagnostic accuracy to 86.7%, with a small reduction in sensitivity to 90.0%. CONCLUSIONS: The diagnostic accuracy of PET-CT in the evaluation of pulmonary mass lesions using the conventional SUVmax cut-off of 2.5 was reduced in a TB-endemic area. An SUVmax cut-off of 5.0 has a higher specificity and diagnostic accuracy for malignancy, with a comparable sensitivity.

Transthoracic ultrasonography in respiratory medicine.

Transthoracic ultrasonography (US) has become an essential modality for the evaluation of a wide range of thoracic pathologies by respiratory, emergency and critical care physicians. It can be performed with entry-level equipment and by personnel with minimal training. Its advantages include low cost, lack of radiation and immediate application at the point of care. The main indications for transthoracic US are the qualitative and quantitative assessment of pleural effusions, pleural thickening, diaphragmatic pathology, and chest wall and pleural tumours. US may also be used to visualise pulmonary pathologies that abutt the pleura, including consolidation and the interstitial syndrome. Transthoracic US is at least as sensitive as chest radiographs in the detection of pneumothoraces, and is useful in diagnosing skeletal abnormalities like rib fractures. It is the ideal tool to guide transthoracic procedures, including thoracocentesis and pleural biopsy. Moreover, US-assisted procedures can be performed by a single clinician with no sedation and minimal monitoring. US-assisted fine needle aspiration and/or cutting needle biopsy of extrathoracic lymph nodes, lesions arising from the chest wall, pleura, peripheral lung and mediastinum are safe and have a high yield in the of hands of clinicians. US can potentially also guide aspiration and biopsy of diffuse pulmonary infiltrates, consolidations and lung abscesses. Transthoracic US may also be used for the detection of pulmonary embolism.

Toxic epidermal necrolysis and Stevens-Johnson syndrome in South Africa: a 3-year prospective study.

BACKGROUND: Toxic Epidermal Necrolysis (TEN) and Stevens-Johnson syndrome (SJS) remain feared medication-related reactions. HIV infection and tuberculosis predispose to drug eruptions, yet there is a paucity of data on TEN/SJS in populations with high prevalences of both diseases. AIM: The aim of this prospective observational study was to describe the features and outcomes of patients admitted with TEN/SJS at a large academic hospital in South Africa. We aimed to identify poor prognostic indicators and to validate the use of the TEN-specific severity-of-illness score (SCORTEN) in this population. METHODS: All patients admitted with TEN/SJS over a 3-year period were enrolled. Disease severity was graded according to percentage skin involved and SCORTEN. Co-morbid diagnoses, clinical features, investigations, complications and outcomes were noted. RESULTS: 75 patients (39.9 ± 10.6 years, 16 males, 59 HIV positive) were classified as TEN (n = 42), TEN/SJS overlap (n = 11) and SJS (n = 22). Twenty-four percent died, most from refractory septic shock. Non-survivors had a higher mean SCORTEN on Days 1 and 3 (1.89 vs. 1.04, P = 0.006 and 2.27 vs. 0.90, P < 0.001). A SCORTEN ≥2 on Days 1 and 3 predicted non-survival (OR = 2.94, P = 0.047; OR = 7.45, P < 0.001). Other predictors of non-survival included HIV infection (OR = 6.01, P = 0.058), HIV-tuberculosis co-infection (OR = 8.5, P < 0.001), ≥40% skin involvement (OR = 20.27, P < 0.001), anaemia (OR = 4.68, P = 0.005), hypoalbuminemia (OR = 8.5, P = 0.001) and severe sepsis (OR = 71.09, P < 0.001). CONCLUSION: Most patients with TEN/SJS were HIV positive and female. We validated the use of SCORTEN and identified several prognostic indicators, most significant being HIV-tuberculosis co-infection, ≥40% skin involvement and severe sepsis.

High mortality from respiratory failure secondary to swine-origin influenza A (H1N1) in South Africa.

BACKGROUND: The novel influenza A (H1N1) pandemic affected South Africa late during the 2009 Southern hemisphere winter and placed an extra burden on a health care system already dealing with a high prevalence of chronic lung diseases and human immunodeficiency virus (HIV) infection. AIM: The aim of this study was to describe the epidemiological characteristics, clinical features, management and outcomes of patients with confirmed influenza A (H1N1) infection complicated by respiratory failure. METHODS: We included all adult patients with confirmed influenza A (H1N1) infection that were referred to the medical intensive care unit of a large academic hospital in Cape Town for ventilatory support in this prospective observational study. RESULTS: A total of 19 patients (39.5 +/- 14.8 years) needed ventilatory support over a 6-week period. Of these, 15 were female and 16 had identifiable risk factors for severe disease, including pregnancy (n = 6), type 2 diabetes mellitus (n = 6), obesity (n = 4), HIV infection (n = 3), immunosuppressive therapy (n = 3) and active pulmonary tuberculosis (n = 2). The most frequent complications were acute renal failure (n = 13), acute respiratory distress syndrome (n = 12) and ventilator associated pneumonia (n = 10). Thirteen patients died (mortality: 68.4%). Fatal cases were significantly associated with an APACHE II score >or=20 (P = 0.034), but not with a P(a)O(2)/F(I)O(2) <200 (P = 0.085) and a chest radiograph score >or=12 (P = 0.134). CONCLUSION: The majority of patients with respiratory failure secondary to influenza A (H1N1) infection were young females and had an underlying risk factor for severe disease. The condition had a high mortality, particularly amongst patients with an APACHE II score >or=20.

Messenger RNA of steroid 21-hydroxylase (CYP21) is expressed in the human hippocampus.

21-hydroxylase converts progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol, the substrates which are required for the production of the main adrenal steroids, corticosterone, aldosterone, and cortisol. As 21-hydroxylase activity has been detected in rodent and fetal human brain, we studied whether and to what extent 21-hydroxylase mRNA is expressed in hippocampal tissue specimens from patients undergoing epilepsy surgery (n=42). 21-hydroxylase mRNA was detected in the hippocampus with an expression 10 000 times lower than in adrenal gland tissue. There was no significant difference in expression levels between women (9.5+/-2.7 arbitrary units (aU); mean+/-SEM) and men (8.0+/-2.2 aU); however, mRNA concentrations in the hippocampus of children (n=4, 1.8+/-0.5 aU) were considerably lower than in adults (n=38, 8.6+/-1.7 aU). The expression of 21-hydroxylase mRNA in the hippocampus suggests that this human brain area has the enzymatic capability to convert progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol.

Neuroactive steroids and seizure susceptibility.

There is increasing clinical and experimental evidence that hormones, in particular sex steroid hormones, influence neuronal excitability and other brain functions. The term 'neuroactive steroids' has been coined for steroids that interact with neurotransmitter receptors. One of the best characterized actions of neuroactive steroids is the allosteric modulation of GABA(A)-receptor function via binding to a putative steroid-binding site. Since neuroactive steroids may interact with a variety of other membrane receptors, excitatory as well as inhibitory, they may have an impact on the excitability of specific brain regions. Neuronal excitability is enhanced by estrogen, whereas progesterone and its metabolites exert anticonvulsant effects. Testosterone and corticosteroids have less consistent effects on seizure susceptibility. Apart from these particular properties, neuroactive steroids may regulate gene expression via progesterone receptors. Based on their molecular properties, these compounds appear to have a promising therapeutical profile for the treatment of different neuropsychiatric diseases including epilepsy. This review focuses on the effects of neuroactive steroids on neuronal excitability and their putative impact on the physiology of epileptic disorders.

Characterization of the 5alpha-reductase-3alpha-hydroxysteroid dehydrogenase complex in the human brain.

Although androgen metabolism in the human brain was discovered almost 30 yr ago, conclusive studies on the enzymes involved are still lacking. We therefore investigated 5alpha-reductase and colocalized 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD) activity in cerebral neocortex (CX) and subcortical white matter (SC) specimens neurosurgically removed from 44 patients suffering from epilepsy. We could demonstrate the presence of the 5alpha-reductase-3alpha-HSD complex in the biopsies of all patients under investigation. Inhibition experiments with specific inhibitors for 5alpha-reductase type 1 and type 2 revealed strong evidence for the exclusive activity of the type 1 isoform. We detected a significantly higher 5alpha-reductase activity in CX than in SC (P< 0.0001), but no sex-specific differences were observed. Furthermore, we found that, in contrast to liver, only 3alpha-HSD type 2 messenger RNA is expressed in the brain and that its expression is significantly higher in SC than in CX without sex-specific differences. The present study is the first to systematically characterize the 5alpha-reductase-3alpha-HSD complex in the human brain. The lack of sex-specific differences and also the colocalization of both enzymes at all life stages suggest a more general purpose of the complex, e.g. the synthesis of neuroactive steroids or the catabolism of neurotoxic steroids, rather than control of reproductive functions.

Expression of the 17beta-hydroxysteroid dehydrogenase type 5 mRNA in the human brain.

An enzyme-mediated metabolism of androgens and estrogens including 17beta-HSD activity in the brain of vertebrates was discovered approximately 30 years ago. Mainly 5alpha-reductase and aromatase have been studied in detail. Recently we could demonstrate reductive and oxidative 17beta-HSD activity as well as considerable mRNA expression of the 17beta-HSD types 3 and 4 in the human brain. In the present study, we report on 17beta-HSD type 5 mRNA expression in brain tissue of women and men. Data analysis did not reveal sex specific differences, but we determined a significantly higher mRNA concentration in the subcortical white matter (SC) than in the cerebral cortex (CX). Investigation of reductive 17beta-HSD in vitro activity with 2 microM androstenedione as the substrate revealed no sex specific differences. Testosterone formation was significantly higher in SC than in CX. Moreover, enzyme activity was significantly higher in brain tissue of adults compared to that of children.

Corticosteroid receptor mRNA expression in the brains of patients with epilepsy.

The effects of corticosteroids in the brain are mediated through the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR). We used a sensitive competitive RT-PCR assay to quantify the amounts of GR and MR mRNA in human brain tissue specimens from patients with focal epilepsies. GR and MR mRNAs were expressed at approximately the same levels in the temporal lobe, frontal lobe, and hippocampus as compared to tissues with high glucocorticoid/mineralocorticoid receptor expression (liver/kidney). GR and MR mRNA concentrations in the temporal lobe increased markedly during childhood and reached adult levels at puberty. GR and MR mRNA expression was significantly higher in the temporal lobe and frontal lobe cortex of women than in those of men. In women, MR and GR mRNA concentrations were markedly lower in hippocampal tissue than in frontal and temporal lobe cortex tissue. In conclusion, our data demonstrate sex- and site-dependent expression of corticosteroid receptor mRNA in the human brain.

Androgen receptor mRNA expression in the human hippocampus.

The androgen receptor (AR) plays a central role in mediating androgen action. Since the hippocampus is a target of steroid modulation, we studied the expression of AR mRNAs in hippocampal tissue specimens from patients undergoing epilepsy surgery (n=42). AR mRNA expression was in the same order of magnitude than in prostate tissue, known for its high expression of AR. AR mRNA concentrations showed no significant difference in AR mRNA expression between men (49.3+/-8.0 arbitrary units (aU); mean+/-SEM) and women (54.3+/-11.2 aU) and no sex-specific hippocampal lateralization pattern was observed. No relationship could be detected between duration of epilepsy, individual seizure frequency, age of the patients and the expression levels of AR. The high expression of AR in the hippocampus suggests that this human brain area is an important target for androgen action.

Serum androgens return to normal after temporal lobe epilepsy surgery in men.

BACKGROUND: Epileptic discharges from the temporal lobe may influence the release of hormones from the hypothalamic-pituitary axis. If epilepsy surgery influences the underlying epileptic disorder one might expect serum hormone concentrations to return to normal following surgery. PATIENTS: Twenty-two men with epilepsy aged 25 to 48 years (mean, 34.9 years) were investigated before surgery and at 3, 6, and 12 months after surgery. Medication (all patients received carbamazepine) was maintained following surgery. METHODS: Hormone measurements included luteinizing hormone, follicle stimulating hormone, estradiol, testosterone, free testosterone, androstenedione, prolactin, dehydroepiandrosterone sulfate, cortisol, growth hormone, and sex hormone-binding globulin. These hormone levels were compared with those of 105 healthy men (mean age, 33.9 years). RESULTS: Fourteen of the 22 patients (63.6%) achieved total seizure control following epilepsy surgery. The 14 patients with successful seizure control entered further analysis. Before surgery these patients' free testosterone and androstenedione concentrations were significantly lower compared with healthy men. In seven of the 14 patients a significant increase of hormone serum concentrations could be demonstrated for testosterone, free testosterone, and androstenedione. Laterality of epileptic focus, enzyme-inducing medication, stress, and the decreasing number of patients during the follow-up did not correlate with the finding of a normalization of serum androgens. PATIENTS without complete seizure control did not show an increase in serum androgen concentrations. CONCLUSION: Successful temporal lobe epilepsy surgery may lead to a normalization of serum androgen concentrations in men with epilepsy.

Differential mRNA expression of the two mineralocorticoid receptor splice variants within the human brain: structure analysis of their different DNA binding domains.

In human brain tissue, cortisol action, at basal concentrations, is mediated by the mineralocorticoid receptor (MR). An in-frame insertion of 12 bp in the MR-DNA-binding domain due to alternative splice site usage between exons 3 and 4 results in an MR mRNA splice variant (MR+4) encoding a receptor protein with four additional amino acids compared to the wild-type MR protein. To elucidate the questions of sex, age, and/or tissue dependent differences of the relative amount of the two mRNA subtypes, we examined 131 fresh human brain tissue samples from temporal and frontal lobe or hippocampus. One hundred and twenty samples were obtained from patients with epilepsy and 11 samples from patients with brain tumours. A small but significant difference of the MR+4 mRNA splice variant proportions in cortex (9.5 +/- 0.8%) and subcortical white matter (6.6 +/- 0.7%) of the temporal lobe could be detected, indicating differential MR splice variant expression within these brain areas. Moreover, the splice variant ratios in samples of the temporal lobe cortex collected from patients with epilepsy differed from samples of patients with brain tumours. These data point to an altered expression of the MR splice variants in epilepsy, and strengthen the supposition of a tissue specific alternative splicing of the MR mRNA. The frequent occurrence of the MR+4 transcript raises the question of its functional significance. For this reason, an MR+4 DNA-binding-domain structure model was generated by computer-based homology modelling based on the known glucocorticoid receptor structure. The data obtained revealed no distorting effect of the inserted four amino acids on the adjacent secondary structures, thereby suggesting that both zinc fingers retain their function. The resulting structure of the MR+4 model leads to the supposition that the receptor retains its function. Moreover, databank analysis with respect to this kind of steroid receptor variation and our own sequence data of the closely related progesterone receptor sustained the hypothesis that only corticosteroid receptors were affected by this alternative splicing event.

Expression of mRNAs encoding for 17beta-hydroxisteroid dehydrogenase isozymes 1, 2, 3 and 4 in epileptic human hippocampus.

Sex steroid hormones exert important influences on neuroendocrine and behavioural brain function. As neuroactive steroids they are able to modify neuronal excitability. Unbalanced synthesis may thus be implicated in pathophysiological conditions, such as epilepsy, migraine, depression and anxiety. In sex steroid metabolism, 17beta-hydroxisteroid dehydrogenases (17beta-HSDs) play a crucial role in catalyzing the final steps of androgen and estrogen biosynthesis. The hippocampus appears to be a major target area of neurosteroidal action. The expression of 17beta-HSD isozymes has not yet been studied in human hippocampus. Therefore, we investigated the expression of 17beta-HSD 1, 2, 3 and 4 mRNAs in hippocampal tissue specimens obtained at neurosurgery from 42 patients with pharmacoresistant temporal lobe epilepsy. A competitive RT-PCR assay was used to quantify the mRNA transcript level. 17beta-HSD 1 mRNA concentrations were 10000 fold lower in the hippocampus compared to placental tissue, whereas 17beta-HSD 3 mRNA concentrations were 50 fold lower than in testis and 17beta-HSD 4 concentrations were in the same order of magnitude as in liver. 17beta-HSD 2 mRNA was not expressed. 17beta-HSD 1, 3 and 4 mRNA concentrations in the hippocampus showed no significant differences between men and women and there were no significant differences in expression levels of these enzymes between patients with Ammon's horn sclerosis (AHS) and those with histopathologically normal hippocampus associated with extrahippocampal lesions. No significant correlation could be detected between duration of epilepsy, individual seizure frequency and expression levels of 17beta-HSDs. In conclusion, the present study is the first to demonstrate mRNA expression of 17beta-HSD 1, 3 and 4 in the epileptic human hippocampus. Together with data on 5alpha-reductase 1, 3alpha-hydroxisteroid oxidoreductase 2 and cytochrome P450scc, previously shown to be expressed in the human hippocampus also, our data provide further evidence for the existence of sex steroid formation and metabolism in this specific brain area.

Expression of mineralocorticoid and glucocorticoid receptor mRNA in the human hippocampus.

The genomic effects of corticosteroids in the brain are mediated through two receptors with a high affinity for cortisol: the glucocorticoid and mineralocorticoid receptor (GR/MR). We used competitive reverse transcription-polymerase chain reaction to quantify the amount of MR and GR mRNA in hippocampal tissue obtained from patients with temporal lobe epilepsy. MR and GR mRNA were expressed at approximately the same levels as in tissues known for high glucocorticoid/mineralocorticoid sensitivity, i.e. liver or kidney. MR mRNA concentrations were significantly higher in the hippocampus of women (0.24+/-0.04 aU, arbitrary units; mean+/-SEM) than in men (0.14+/-0.01 aU, P<0.006) or children (0.09+/-0.02, P<0. 007). No such differences were observed for GR mRNA expression.