Prognosis and conditional survival among women with newly diagnosed ovarian cancer.

OBJECTIVE: An important question in determining long-term prognosis for women with ovarian cancer is whether risk of death changes the longer a woman lives. Large real-world datasets permit assessment of conditional survival (CS) given both prior overall survival (OS) and real-world progression-free survival (rwPFS). METHODS: Using a longitudinal dataset from US oncology centers, this study included 6778 women with ovarian cancer. We calculated CS rates as the Kaplan-Meier probability of surviving an additional 1 or 5 years, given no mortality (OS) or disease progression (rwPFS) event in the previous 0.5-5 years since first-line chemotherapy initiation, adjusted for factors associated with OS based on multivariable Cox regression. RESULTS: Median study follow-up was 9 years (range, 1-44) from first-line initiation to data cutoff (17-Feb-2021). Median OS was 58.0 months (95% CI, 54.9-60.8); median rwPFS was 18.4 months (17.4-19.4). The adjusted 1-year CS rate (ie, rate of 1 year additional survival) did not vary based on time alive, whereas the adjusted 5-year CS rate increased from 48.5% (47.0%-50.1%) for women who had already survived 6 months to 66.4% (63.3%-69.6%) for those already surviving 5 years (thus surviving 10 years total). The adjusted 1-year CS rate increased from 90.4% (89.5%-91.4%) with no rwPFS event at 6 months to 97.6% (96.4%-98.8%) with no rwPFS event at 5 years; adjusted 5-year CS rate increased from 53.7% (52.0%-55.5%) to 85.0% (81.2%-88.9%), respectively. CONCLUSIONS: This analysis extends the concept of CS by also conditioning on time progression-free. Patients with longer rwPFS experience longer survival than patients with shorter rwPFS.

Management of acute appendicitis during the COVID-19 pandemic: a retrospective cohort study.

BACKGROUND: The Coronavirus Disease 2019 (COVID-19) pandemic profoundly impacted delivery of health care. South Western Sydney Local Health District (SWSLHD) experienced some of the highest cases, admissions and deaths during the Delta and Omicron waves in New South Wales. This study aims to determine the impact of the pandemic on emergency surgery services for adults presenting with acute appendicitis. METHODS: A retrospective review of patient records was performed of adults presenting with acute appendicitis between 1st March 2021 and 31st March 2022, which was compared to a pre-COVID control period of the same dates in 2019-2020. Patients managed operatively or conservatively were included. RESULTS: 1556 patients were included in the operative arm; 723 and 833 respectively in the study and control groups, which were comparable at baseline. 1.66% were COVID positive. During the pandemic, patients were significantly more likely to be investigated with computered tomography (CT) scan (p ≤ 0.001), present with complicated appendicitis (p = 0.03), and require caecectomy (p = 0.005). They had higher American Society of Anaesthesiology (ASA) scores (p = 0.001) and significantly lower negative appendectomy rates (p = 0.001). Fifty-two patients were included in the conservative arm; 29 and 23 respectively in the pandemic and control groups. Patients were comparable at baseline. There were two COVID positive patients. During the pandemic, there was a significant reduction in complications (p = 0.033), readmissions (0.044) and interval appendicectomy (p = 0.0044). CONCLUSION: We identified higher rates of complicated appendicitis, caecectomies and greater reliance on CT imaging preoperatively during the pandemic in SWSLHD.

Reducing mortality in mucormycosis of the head and neck in diabetic patients: A CARE case series.

INTRODUCTION: Rhinocerebral mucormycosis is extremely fatal, with mortality rates ranging from 85-93% despite the best treatment in immunocompromised patients. We emphasize the importance of early diagnosis, repeated debridement, and aggressive antifungal treatment to reduce mortality. CASE SUMMARY: We report six cases (five male and one female), with a mean age of 51 years who were diagnosed to have mucormycosis from 2017 to 2019. All patients were diabetic. Intracranial involvement and orbital involvement were found in four cases. Facial nerve palsy was seen in two cases, one without any apparent otological involvement. Aggressive serial debridement and amphotericin B was started. Posaconazole was added subsequently to the treatment in two cases. One patient succumbed to the disease five months after discharge. The other five patients are on regular follow-up for a mean duration of 14 months at the end of which two had residual disease which was under control. DISCUSSION: Repeated surgical debridement with an early aggressive and combination antifungal therapy can result in good outcomes even in advanced mucormycosis. Concurrent management of the underlying pathology, monitoring of liver and kidney functions, and therapeutic drug monitoring are useful to ensure smooth and effective treatment.

Real-World Healthcare Resource Utilization in Patients with Classical Hodgkin Lymphoma Treated with Pembrolizumab and Nivolumab in the USA.

BACKGROUND: Patients with classical Hodgkin lymphoma (cHL) relapsed or refractory (R/R) disease who relapse after or are ineligible for autologous stem cell transplantation have a poor prognosis. Recently, the anti-PD1 monoclonal antibodies nivolumab and pembrolizumab were approved by the US Food and Drug Administration (FDA; May 2016 and March 2017, respectively) as treatment options for R/R cHL patients. OBJECTIVE: In the absence of comparative clinical trials between these agents, this observational study was conducted to evaluate the healthcare resource utilization (HRU) of patients with cHL initiated on pembrolizumab compared to nivolumab in the USA. PATIENTS AND METHOD: Healthcare insurance claims from Symphony Health's IDV® (Integrated Dataverse) (July 2014-June 2018) were used in this retrospective study. The study population included adult patients with cHL initiated on pembrolizumab or nivolumab (index date). Inverse probability of treatment weighting was used to adjust for differences in patient characteristics between cohorts. All-cause and cHL-related hospitalizations and outpatient visits were measured during the observation (post-index) period and reported per patient-year (PPY). Rates of HRU were compared between cohorts using rate ratios (RRs). RESULTS: A total of 92 and 218 patients initiated on pembrolizumab and nivolumab, respectively, were included in the study population. After weighting, the mean age was similar at 55 years in both cohorts, while the proportion of females was lower in the pembrolizumab cohort (35.3%) compared to the nivolumab cohort (44.1%). Mean Quan-Charlson Comorbidity Index score was well balanced after weighting in the pembrolizumab and nivolumab cohorts (4.2 and 4.3, respectively). During the observation period, patients in the pembrolizumab cohort had significantly lower rates of all-cause hospitalizations (RR [95% CI] 0.33 [0.09-0.80]) and cHL-related hospitalizations (RR [95% CI] 0.14 [0.02-0.37]) than those in the nivolumab cohort. Rates of all-cause and cHL-related outpatient visits were not statistically different between patients in the pembrolizumab and nivolumab cohorts. CONCLUSIONS: In this real-world study, adult cHL patients initiated on pembrolizumab had significantly lower rates of all-cause and cHL-related hospitalizations compared to patients initiated on nivolumab.

Correlation of cochlear nerve cross-sectional area and auditory performance after cochlear implantation in prelingual children with bilateral profound hearing loss.

OBJECTIVE: To assess whether cochlear nerve (CN) cross-sectional area as measured with parasagittal magnetic resonance imaging (MRI) in prelingual pediatric deaf patients correlates with auditory performance after cochlear implantation. STUDY DESIGN: Prospective Cohort study. METHODS: Thirty-two prelingual children with bilateral profound sensorineural hearing loss (SNHL) who received unilateral cochlear implant were included in this study. Diameters of CN at Internal auditory canal (IAC) fundus and mid-point of IAC were retrospectively measured on parasagittal images of FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence MRI by two independent observers. Cross-sectional areas [π (Height/2) (Width/2)] were then correlated with post-operative CAPS (Categories of Auditory Performance) and IT-MAIS (Infant-Toddler Meaningful Auditory Integration Scale) scores regularly assessed at 3 monthly intervals post device activation. RESULTS: The cochlear nerve was identified in all the 32 patients. Mean cross-sectional areas (CSA) of cochlear nerve were 0.71 ± 0.16 mm2 at IAC fundus and 0.73 ± 0.18 mm2 at mid-point of IAC. The correlation value between CSA at mid-point of IAC and CAPS score at 6 months was 0.271 (p-value- 0.140) and correlation value between CSA at mid-point of IAC and IT-MAIS score at 6 months was 0.282 (p-value- 0.124) which were statistically not significant. CONCLUSION: There was no significant correlation between the cross-sectional areas of the cochlear nerve on MRI and postoperative auditory scores as measured by CAPS and IT-MAIS scores at six months from the device activation. Hence, we conclude that above an adequate diameter, which can affect the minimum required neurons, the changes in the diameter do not have significant bearing on auditory outcomes after cochlear implantation.

Post-rhinoplasty outcomes in an Indian population assessed using the FACE-Q appraisal scales: a prospective observational study.

OBJECTIVES: The primary goal of rhinoplasty is patient satisfaction and improved quality of life. The present study was conducted to assess patient satisfaction with face and nose appearance, and quality of life after rhinoplasty. METHODS: Patients presenting for rhinoplasty completed the FACE-Q survey. This is a new instrument that measures patient-reported outcomes in those undergoing aesthetic procedures. The FACE-Q scales include satisfaction with facial appearance overall, satisfaction with the nose, psychological well-being, psychosocial distress and social function. RESULTS: Sixty-five patients completed the FACE-Q at pre-operative and at post-operative follow-up visits. Post-operative scores increased significantly in terms of: satisfaction with facial appearance (p < 0.0001, t = 15.639, degrees of freedom = 64); social function (p < 0.0001, t = 12.208, degrees of freedom = 64); psychosocial distress (p < 0.0001, t = 13.864, degrees of freedom = 64); psychological function (p < 0.0001, t = 12.681, degrees of freedom = 64); and satisfaction with nose (p < 0.0001, t = 16.421, degrees of freedom = 64). Most patients reported more than 79 per cent satisfaction with the post-operative outcome. CONCLUSION: The FACE-Q is an adequate instrument for determining successful aesthetic surgery based on patient satisfaction.

Aging phenotype(s) in kidneys of diabetic mice are p66ShcA dependent.

The p66ShcA protein controls cellular responses to oxidative stress, senescence, and apoptosis. Here, we test the hypothesis that aging phenotype(s) commonly associated with the broad category of chronic kidney disease are accelerated in diabetic kidneys and linked to the p66ShcA locus. At the organ level, tissue stem cells antagonize senescent phenotypes by replacing old dysfunctional cells. Using established methods, we isolated a highly purified population of stem cell antigen-1-positive mesenchymal stem cells (Sca-1+ MSCs) from kidneys of wild-type (WT) and p66 knockout (p66 KO) mice. Cells were plated in culture medium containing normal glucose (NG) or high glucose (HG). Reactive oxygen species (ROS) metabolism was substantially increased in WT MSCs in HG medium in association with increased cell death by apoptosis and acquisition of the senescent phenotype. DNA microarray analysis detected striking differences in the expression profiles of WT and p66 KO-MSCs in HG medium. Unexpectedly, the analysis for p66 KO-MSCs revealed upregulation of Wnt genes implicated in self-renewal and differentiation. To test the in vivo consequences of constitutive p66 expression in diabetic kidneys, we crossed the Akita diabetic mouse with the p66KO mouse. Homozygous mutation at the p66 locus delays or prevents aging phenotype(s) in the kidney that may be precursors to diabetic nephropathy.

Novel role for IL-22 in protection during chronic Mycobacterium tuberculosis HN878 infection.

Approximately 2 billion people are infected with Mycobacterium tuberculosis (Mtb), resulting in 1.4 million deaths every year. Among Mtb-infected individuals, clinical isolates belonging to the W-Beijing lineage are increasingly prevalent, associated with drug resistance, and cause severe disease immunopathology in animal models. Therefore, it is exceedingly important to identify the immune mechanisms that mediate protection against rapidly emerging Mtb strains, such as W-Beijing lineage. IL-22 is a member of the IL-10 family of cytokines with both protective and pathological functions at mucosal surfaces. Thus far, collective data show that IL-22 deficient mice are not more susceptible to aerosolized infection with less virulent Mtb strains. Thus, in this study we addressed the functional role for the IL-22 pathway in immunity to emerging Mtb isolates, using W-Beijing lineage member, Mtb HN878 as a prototype. We show that Mtb HN878 stimulates IL-22 production in TLR2 dependent manner and IL-22 mediates protective immunity during chronic stages of Mtb HN878 infection in mice. Interestingly, IL-22-dependent pathways in both epithelial cells and macrophages mediate protective mechanisms for Mtb HN878 control. Thus, our results project a new protective role for IL-22 in emerging Mtb infections.

The Learning Curve of Pure Retroperitoneoscopic Donor Nephrectomy.

BACKGROUND: Retroperitoneoscopic donor nephrectomy (RDN) is a well-established modality for the procurement of kidneys for renal transplantation. However the learning curve of pure RDN is not yet defined. Defining the learning curve will help in proper mentorship of the new donor surgeons besides providing safety to the donors. OBJECTIVE: To define the learning curve of pure RDN. METHODS: We analyzed the prospectively collected data of 102 voluntary kidney donors who underwent RDN by a single surgeon between August 2012 and April 2015 at our center. The donors were classified into group A (1-34), group B (35-68), and group C (69-102) according to the chronological order of their surgery. Left RDN was performed in 28 (82%), 25 (74%), and 28 (82%) donors of group A, B, and C, respectively. Right RDN was performed in 6 (18%), 9 (26%), and 6 (18%) donors of group A, B, and C, respectively. The clinical data were analyzed for each group. RESULTS: Statistically significant difference was observed for the mean operative time (p<0.01) and warm ischemia time (p<0.04). The operative time remained around 200 minutes after the initial 35 cases. CONCLUSION: The learning curve of pure RDN was 35 cases, although the mastery requires more number of cases to be performed.

The non-human primate model of tuberculosis.

Non-human primates (NHPs) are used to model human disease owing to their remarkably similar genomes, physiology, and immune systems. Recently, there has been an increased interest in modeling tuberculosis (TB) in NHPs. Macaques are susceptible to infection with different strains of Mycobacterium tuberculosis (Mtb), producing the full spectrum of disease conditions, including latent infection, chronic progressive infection, and acute TB, depending on the route and dose of infection. Clearly, NHPs are an excellent model of human TB. While the initial aim of the NHP model was to allow preclinical testing of candidate vaccines and drugs, it is now also being used to study pathogenesis and immune correlates of protection. Recent advances in this field are discussed in this review. Key questions such as the effect of hypoxia on the biology of Mtb and the basis of reactivation of latent TB can now be investigated through the use of this model.

Thoracic epidural for post-thoracotomy pain: a comparison of three concentrations of sufentanil in bupivacaine

ABSTRACT. Background:The aim of this prospective, double blind, randomised trial was to compare the analgesic and adverse effectsof three concentrations of the thoracic epidural sufentanil with bupivacaine in patients undergoing thoracotomy.Methods:We studied 60 (randomised) patients who were to receive a 10 ml bolus dose of sufentanil, 1µg/ml, 2 µg/ml and3 µg/ml, in bupivacaine 0.125%, via thoracic epidural. Postoperatively, pain at rest, on coughing and with ambulation wasassessed using a visual analogue scale (VAS) and observer verbal ranking score (OVRS) at 2, 6, 12 and 24 hours. Adverseeffects were simultaneously assessed.Results:There was no significant difference in the baseline characteristics between the three groups. The number of patientswith episodes of unsatisfactory pain, i.e. a VAS scores ≥ 40 and OVRS ≥ 2, at each of the four assessments postoperatively,was significantly higher with sufentanil 1 g/ml than with sufentanil 2 µg/ml or µ3 g/ml (p < 0.05). In the 3 µg/ml sufentanilgroup, four patients (20%) had a sedation score ≥ 3 compared with one (5%) and no (0%) patients in the 2 µg/ml and1 µg/ml sufentanil groups, respectively (p < 0.05). In addition, 30% patients experienced pruritus in the 3 µg/ml sufentanilgroup compared with 10% and 5%, respectively, in the 2 µg/ml and 1 µg/ml sufentanil groups. In the sufentanil 3 µg/ml,2 µg/ml and 1 µg/ml groups, 30%, 20% and 5% patients, respectively, had emetics symptoms (p < 0.05).Conclusions:We conclude that a thoracic epidural bolus of 10 ml sufentanil 2 µg/ml with bupivacaine 0.125% provides theoptimal balance between pain relief and side-effects following thoracotomy

Stem cell-associated genes are extremely poor prognostic factors for soft-tissue sarcoma patients.

Cancer stem cells can play an important role in tumorigenesis and tumor progression. However, it is still difficult to detect and isolate cancer stem cells. An alternative approach is to analyse stem cell-associated gene expression. We investigated the coexpression of three stem cell-associated genes, Hiwi, hTERT and survivin, by quantitative real-time-PCR in 104 primary soft-tissue sarcomas (STS). Multivariate Cox's proportional hazards regression analyses allowed correlating gene expression with overall survival for STS patients. Coexpression of all three stem cell-associated genes resulted in a significantly increased risk of tumor-related death. Importantly, tumors of patients with the poorest prognosis were of all four tumor stages, suggesting that their risk is based upon coexpression of stem cell-associated genes rather than on tumor stage.

Expression of the stem cell self-renewal gene Hiwi and risk of tumour-related death in patients with soft-tissue sarcoma.

Self-renewal is considered as a common property of stem cells. Dysregulation of stem cell self-renewal is likely a requirement for the development of cancer. Hiwi, the human Piwi gene, encodes a protein responsible for stem cell self-renewal. In this study, we investigated the expression of Hiwi at the RNA level by real-time quantitative PCR in 65 primary soft-tissue sarcomas (STS) and ascertained its impact on prognosis for STS patients. In a multivariate Cox's proportional hazards regression model, we found that an increased expression of Hiwi mRNA is a significant negative prognostic factor for patients with STS (P=0.017; relative risk 4.6, 95% confidence interval (CI) 1.3-16.1) compared to medium expression of Hiwi transcript. However, a low expression of Hiwi transcript is correlated with a 2.4-fold (CI 0.7-8.0) increased risk, but this effect was not significant (P=0.17). Altogether, high-level expression of Hiwi mRNA identifies STS patients at high risk of tumour-related death. This is the first report showing a correlation between expression of a gene involved in stem cell self-renewal and prognosis of cancer patients.

Aneuploid neurons are functionally active and integrated into brain circuitry.

The existence of aneuploid cells within the mammalian brain has suggested the influence of genetic mosaicism on normal neural circuitry. However, aneuploid cells might instead be glia, nonneural, or dying cells, which are irrelevant to direct neuronal signaling. Combining retrograde labeling with FISH for chromosome-specific loci, distantly labeled aneuploid neurons were observed in expected anatomical projection areas. Coincident labeling for immediate early gene expression indicated that these aneuploid neurons were functionally active. These results demonstrate that functioning neurons with aneuploid genomes form genetically mosaic neural circuitries as part of the normal organization of the mammalian brain.

Chromosomal variation in neurons of the developing and adult mammalian nervous system.

A basic assumption about the normal nervous system is that its neurons possess identical genomes. Here we present direct evidence for genomic variability, manifested as chromosomal aneuploidy, among developing and mature neurons. Analysis of mouse embryonic cerebral cortical neuroblasts in situ detected lagging chromosomes during mitosis, suggesting the normal generation of aneuploidy in these somatic cells. Spectral karyotype analysis identified approximately 33% of neuroblasts as aneuploid. Most cells lacked one chromosome, whereas others showed hyperploidy, monosomy, and/or trisomy. The prevalence of aneuploidy was reduced by culturing cortical explants in medium containing fibroblast growth factor 2. Interphase fluorescence in situ hybridization on embryonic cortical cells supported the rate of aneuploidy observed by spectral karyotyping and detected aneuploidy in adult neurons. Our results demonstrate that genomes of developing and adult neurons can be different at the level of whole chromosomes.

Requirement for the lpA1 lysophosphatidic acid receptor gene in normal suckling behavior.

Although extracellular application of lysophosphatidic acid (LPA) has been extensively documented to produce a variety of cellular responses through a family of specific G protein-coupled receptors, the in vivo organismal role of LPA signaling remains largely unknown. The first identified LPA receptor gene, lp(A1)/vzg-1/edg-2, was previously shown to have remarkably enriched embryonic expression in the cerebral cortex and dorsal olfactory bulb and postnatal expression in myelinating glia including Schwann cells. Here, we show that targeted deletion of lp(A1) results in approximately 50% neonatal lethality, impaired suckling in neonatal pups, and loss of LPA responsivity in embryonic cerebral cortical neuroblasts with survivors showing reduced size, craniofacial dysmorphism, and increased apoptosis in sciatic nerve Schwann cells. The suckling defect was responsible for the death among lp(A1)((-/-)) neonates and the stunted growth of survivors. Impaired suckling behavior was attributable to defective olfaction, which is likely related to developmental abnormalities in olfactory bulb and/or cerebral cortex. Our results provide evidence that endogenous lysophospholipid signaling requires an lp receptor gene and indicate that LPA signaling through the LP(A1) receptor is required for normal development of an inborn, neonatal behavior.

Neurobiology of receptor-mediated lysophospholipid signaling. From the first lysophospholipid receptor to roles in nervous system function and development.

Identification of the first lysophospholipid receptor, LPA1/Vzg-1, cloned by way of neurobiological analyses on the embryonic cerebral cortex, has led to the realization and demonstration that there exist multiple, homologous LP receptors, including those encoded by a number of orphan receptor genes known as "Edg," all of which are members of the G-protein-coupled receptor (GPCR) superfamily. These receptors interact with apparent high affinity for lysophosphatidic acid (LPA) or sphingosine-1-phosphate (S1P or SPP), and are referred to based upon their functional identity as lysophospholipid receptors: LPA and LPB receptors, respectively, with the expectation that additional subgroups will be identified (i.e., LPC, etc.). Here an update is provided on insights gained from analyses of these receptor genes as they relate to the nervous system, particularly the cerebral cortex, and myelinating cells (oligodendrocytes and Schwann cells).

Expression systems for study of mycobacterial gene regulation and development of recombinant BCG vaccines.

Successful genetic engineering of mycobacteria is crucial for developing new approaches to combat tuberculosis as well as for dissecting out the molecular basis of pathogenesis of Mycobacterium tuberculosis. We have constructed a Mycobacterium-Escherichia coli shuttle expression vector pSD5. It carries a modular expression cassette which provides sites for cloning of promoters, a ribosome binding site (RBS) with an appropriately placed initiation codon and multiple cloning sites for cloning the genes of interest. We also constructed pDK20, an integration proficient derivative of pSD5, by incorporating mycobacteriophage L5 integration signals in lieu of the origin of DNA replication for mycobacteria. This vector permits stable expression of genes in M.bovis BCG, M.smegmatis, and M.tuberculosis under the transcriptional control of a mycobacterial promoter. These vectors enable the expression of a gene to be regulated by several hundred fold depending upon the strength of mycobacterial promoter. We propose that expression of protective antigens using an appropriate promoter derivative of pDK20 should help in development of recombinant BCG vaccines that can induce an optimal immune response from the host. We have further employed the integration proficient expression system for comparing the efficiency and specificity of transcriptional recognition in M.bovis BCG, M.tuberculosis, and M.smegmatis. We show that fast growing M.smegmatis and slow growing M.tuberculosis and M.bovis BCG recognize mycobacterial promoters with comparable efficiency inspite of differences in their growth rates.

Construction of shuttle vectors for genetic manipulation and molecular analysis of mycobacteria.

Two novel shuttle vectors for mycobacteria are described which have been derived from the expression system pSD5 developed in our laboratory. Plasmid pSD5B is a promoter-selection vector containing a promoterless lacZ gene and allows the identification of mycobacterial promoters by the blue colour of the colonies on solid media containing XGal. Moreover, the chronological order of appearance of blue colonies and intensity of colour provide a qualitative index of transcriptional strengths of the cloned promoters. Plasmid pSD5C has been designed to construct mycobacterial genomic libraries and express the cloned DNA inserts as fusion proteins with maltose binding protein in mycobacteria. Libraries in pSD5C provide feasibility for their screening with either DNA probes or specific antisera for identifying the genes of interest and for isolation of specific genetic loci by complementation of Escherichia coli and mycobacterial mutants. These vectors combine the ease of working in E. coli with the advantage of directly propagating them in mycobacteria without further manipulations. Finally, we demonstrate that these vectors function efficiently both in fast growing Mycobacterium smegmatis and slow growing mycobacteria including Mycobacterium tuberculosis and Mycobacterium bovis BCG.

A study of mycobacterial transcriptional apparatus: identification of novel features in promoter elements.

Our earlier studies on transcriptional signals of mycobacteria had revealed that (i) strong promoters occur less frequently in the slowly growing pathogen Mycobacterium tuberculosis H37Rv than in the fast-growing saprophyte M. smegmatis and (ii) mycobacterial promoters function poorly in Escherichia coli. We now present evidence that RNA polymerases of M. smegmatis, M. tuberculosis, and M. bovis BCG recognize promoter elements with comparable efficiencies. Analysis of these randomly isolated mycobacterial promoters by DNA sequencing, primer extension, and deletion experiments revealed that their -10 regions are highly similar to those of E. coli promoters, in contrast to their -35 regions, which can tolerate a greater variety of sequences, owing presumably to the presence of multiple sigma factors with different or overlapping specificities for -35 regions, as reported earlier for the Streptomyces promoters. A comparison of the -10 and -35 binding domains of MysA, HrdB, and RpoD (the principal sigma factors of M. smegmatis, Streptomyces aureofaciens, and E. coli, respectively) showed that all three sigma factors have nearly identical -10 binding domains. However, the -35 binding domains of the principal mycobacterial and streptomycete sigma factors, although nearly identical to each other, are vastly different from the corresponding region of the sigma factor of E. coli. Thus, the transcriptional signals of mycobacteria have features in common with Streptomyces promoters but differ from those of E. coli because of major differences in the -35 regions of the promoters and the corresponding binding domain in the sigma factor.