Evaluating the relationship between ciprofloxacin prescription and non-susceptibility in Salmonella Typhi in Blantyre, Malawi: an observational study

BACKGROUND

Ciprofloxacin is the first-line drug for treating typhoid fever in many countries in Africa with a high disease burden, but the emergence of non-susceptibility poses a challenge to public health programmes. Through enhanced surveillance as part of vaccine evaluation, we investigated the occurrence and potential determinants of ciprofloxacin non-susceptibility in Blantyre, Malawi.

METHODS

We conducted systematic surveillance of typhoid fever cases and antibiotic prescription in two health centres in Blantyre, Malawi, between Oct 1, 2016, and Oct 31, 2019, as part of the STRATAA and TyVAC studies. In addition, blood cultures were taken from eligible patients presenting at Queen Elizabeth Central Hospital, Blantyre, as part of routine diagnosis. Inclusion criteria were measured or reported fever, or clinical suspicion of sepsis. Microbiologically, we identified Salmonella enterica serotype Typhi (S Typhi) isolates with a ciprofloxacin non-susceptible phenotype from blood cultures, and used whole-genome sequencing to identify drug-resistance mutations and phylogenetic relationships. We constructed generalised linear regression models to investigate associations between the number of ciprofloxacin prescriptions given per month to study participants and the proportion of S Typhi isolates with quinolone resistance-determining region (QRDR) mutations in the following month.

FINDINGS

From 46 989 blood cultures from Queen Elizabeth Central Hospital, 502 S Typhi isolates were obtained, 30 (6%) of which had either decreased ciprofloxacin susceptibility, or ciprofloxacin resistance. From 11 295 blood cultures from STRATAA and TyVAC studies, 241 microbiologically confirmed cases of typhoid fever were identified, and 198 isolates from 195 participants sequenced (mean age 12·8 years [SD 10·2], 53% female, 47% male). Between Oct 1, 2016, and Aug 31, 2019, of 177 typhoid fever cases confirmed by whole-genome sequencing, four (2%) were caused by S Typhi with QRDR mutations, compared with six (33%) of 18 cases between Sept 1 and Oct 31, 2019. This increase was associated with a preceding spike in ciprofloxacin prescriptions. Every additional prescription of ciprofloxacin given to study participants in the preceding month was associated with a 4·2% increase (95% CI 1·8-7·0) in the relative risk of isolating S Typhi with a QRDR mutation (p=0·0008). Phylogenetic analysis showed that S Typhi isolates with QRDR mutations from September and October, 2019, belonged to two distinct subclades encoding two different QRDR mutations, and were closely related (4-10 single-nucleotide polymorphisms) to susceptible S Typhi endemic to Blantyre.

INTERPRETATION

We postulate a causal relationship between increased ciprofloxacin prescriptions and an increase in fluoroquinolone non-susceptibility in S Typhi. Decreasing ciprofloxacin use by improving typhoid diagnostics, and reducing typhoid fever cases through the use of an efficacious vaccine, could help to limit the emergence of resistance.

FUNDING

Wellcome Trust, Bill & Melinda Gates Foundation, and National Institute for Health and Care Research (UK).

Efficacy of typhoid conjugate vaccine: final analysis of a 4-year, phase 3, randomised controlled trial in Malawian children

BACKGROUND

Randomised controlled trials of typhoid conjugate vaccines among children in Africa and Asia have shown high short-term efficacy. Data on the durability of protection beyond 2 years are sparse. We present the final analysis of a randomised controlled trial in Malawi, encompassing more than 4 years of follow-up, with the aim of investigating vaccine efficacy over time and by age group.

METHODS

In this phase 3, double-blind, randomised controlled efficacy trial in Blantyre, Malawi, healthy children aged 9 months to 12 years were randomly assigned (1:1) by an unmasked statistician to receive a single dose of Vi polysaccharide conjugated to tetanus toxoid vaccine (Vi-TT) or meningococcal capsular group A conjugate (MenA) vaccine. Children had to have no previous history of typhoid vaccination and reside in the study areas for inclusion and were recruited from government schools and health centres. Participants, their parents or guardians, and the study team were masked to vaccine allocation. Nurses administering vaccines were unmasked. We did surveillance for febrile illness from vaccination until follow-up completion. The primary outcome was first occurrence of blood culture-confirmed typhoid fever. Eligible children who were randomly assigned and vaccinated were included in the intention-to-treat analyses. This trial is registered at ClinicalTrials.gov, NCT03299426.

FINDINGS

Between Feb 21, 2018, and Sept 27, 2018, 28 130 children were vaccinated; 14 069 were assigned to receive Vi-TT and 14 061 to receive MenA. After a median follow-up of 4·3 years (IQR 4·2-4·5), 24 (39·7 cases per 100 000 person-years) children in the Vi-TT group and 110 (182·7 cases per 100 000 person-years) children in the MenA group were diagnosed with a first episode of blood culture-confirmed typhoid fever. In the intention-to-treat population, efficacy of Vi-TT was 78·3% (95% CI 66·3-86·1), and 163 (129-222) children needed to be vaccinated to prevent one case. Efficacies by age group were 70·6% (6·4-93·0) for children aged 9 months to 2 years; 79·6% (45·8-93·9) for children aged 2-4 years; and 79·3% (63·5-89·0) for children aged 5-12 years.

INTERPRETATION

A single dose of Vi-TT is durably efficacious for at least 4 years among children aged 9 months to 12 years and shows efficacy in all age groups, including children younger than 2 years. These results support current WHO recommendations in typhoid-endemic areas for mass campaigns among children aged 9 months to 15 years, followed by routine introduction in the first 2 years of life.

FUNDING

Bill & Melinda Gates Foundation.

Typhoid conjugate vaccine effectiveness in Malawi: evaluation of a test-negative design using randomised, controlled clinical trial data

BACKGROUND

Typhoid conjugate vaccines are being introduced in low-income and middle-income countries to prevent typhoid illness in children. Vaccine effectiveness studies assess vaccine performance after introduction. The test-negative design is a commonly used method to estimate vaccine effectiveness that has not been applied to typhoid vaccines because of concerns over blood culture insensitivity. The overall aim of the study was to evaluate the appropriateness of using a test-negative design to assess typhoid Vi polysaccharide-tetanus toxoid conjugate vaccine (Vi-TT) effectiveness using a gold standard randomised controlled trial database.

METHODS

Using blood culture data from a randomised controlled trial of Vi-TT in Malawi, we simulated a test-negative design to derive vaccine effectiveness estimates using three different approaches and compared these to randomised trial efficacy results. In the randomised trial, 27 882 children aged 9 months to 12 years were randomly assigned (1:1) to receive a single dose of Vi-TT or meningococcal capsular group A conjugate vaccine between Feb 21 and Sept 27, 2018, and were followed up for blood culture-confirmed typhoid fever until Sept 30, 2021.

FINDINGS

For all three test-negative design approaches, vaccine effectiveness estimates (test-negative design A, 80·3% [95% CI 66·2 to 88·5] vs test-negative design B, 80·5% [66·5 to 88·6] vs test-negative design C, 80·4% [66·9 to 88·4]) were almost identical to the randomised trial results (80·4% [95% CI 66·4 to 88·5]). Receipt of Vi-TT did not affect the risk of non-typhoid fever (vaccine efficacy against non-typhoid fever -0·4% [95% CI -4·9 to 3·9] vs -1% [-5·6 to 3·3] vs -2·5% [-6·4 to 1·3] for test-negative design A, test-negative design B, and test-negative design C, respectively).

INTERPRETATION

This study validates the test-negative design core assumption for typhoid vaccine effectiveness estimation and shows the accuracy and precision of the estimates compared with the randomised controlled trial. These results show that the test-negative design is suitable for assessing typhoid conjugate vaccine effectiveness in post-introduction studies using blood culture surveillance.

FUNDING

Bill & Melinda Gates Foundation.

Safety and immunogenicity of a typhoid conjugate vaccine among children aged 9 months to 12 years in Malawi: a nested substudy of a double-blind, randomised controlled trial

BACKGROUND

Typhoid fever is a substantial public health problem in Africa, yet there are few clinical trials of typhoid conjugate vaccine (TCV). We assessed immunogenicity and safety of Typbar TCV in Malawi.

METHODS

This substudy was nested within a phase 3, double-blind, parallel design, randomised controlled trial of TCV in children from Ndirande Health Centre in Ndirande township, Blantyre, Malawi. To be eligible, participants had to be aged between 9 months and 12 years with no known immunosuppression or chronic health conditions, including HIV or severe malnutrition; eligible participants were enrolled into three strata of approximately 200 children (9-11 months, 1-5 years, and 6-12 years), randomly assigned (1:1) to receive TCV or control (meningococcal serogroup A conjugate vaccine [MCV-A]) intramuscularly. Serum was collected before vaccination and at 28 days and 730-1035 days after vaccination to measure anti-Vi antibodies by ELISA. Because of COVID-19, day 730 visits were extended up to 1035 days. This nested substudy evaluated reactogenicity, safety, and immunogenicity by age stratum. Safety outcomes, analysed in the intention-to-treat population, included solicited adverse events within 7 days of vaccination (assessed on 3 separate days) and unsolicited adverse events within 28 days of vaccination. This trial is registered with ClinicalTrials.gov, NCT03299426.

FINDINGS

Between Feb 22 and Sept 6, 2018, 664 participants were screened, and 631 participants were enrolled and randomly assigned (320 to the TCV group and 311 to the MCV-A group). 305 participants in the TCV group and 297 participants in the MCV-A group were vaccinated. Among TCV recipients, anti-Vi IgG geometric mean titres increased more than 500 times from 4·2 ELISA units (EU)/mL (95% CI 4·0-4·4) at baseline to 2383·7 EU/mL (2087·2-2722·3) at day 28, then decreased to 48·0 EU/mL (39·9-57·8) at day 730-1035, remaining more than 11 times higher than baseline. Among MCV-A recipients, anti-Vi IgG titres remained unchanged: 4·3 EU/mL (4·0-4·5) at baseline, 4·4 EU/mL (4·0-4·7) on day 28, and 4·6 EU/mL (4·2-5·0) on day 730-1035. TCV and MCV-A recipients had similar solicited local (eight [3%] of 304, 95% CI 1·3-5·1 and three [1%] of 293, 0·4-3·0) and systemic (27 [9%] of 304, 6·2-12·6 and 27 [9%] of 293, 6·4-13·1) reactogenicity. Related unsolicited adverse events occurred similarly in TCV and MCV-A recipients in eight (3%) of 304 (1·3-5·1) and eight (3%) of 293 (1·4-5·3).

INTERPRETATION

This study provides evidence of TCV safety, tolerability, and immunogenicity up to 730-1035 days in Malawian children aged 9 months to 12 years.

FUNDING

Bill & Melinda Gates Foundation.

A clinical and molecular epidemiological survey of hepatitis C in Blantyre, Malawi, suggests a historic mechanism of transmission

Hepatitis C virus (HCV) is a leading cause of liver disease worldwide. There are no previous representative community HCV prevalence studies from Southern Africa, and limited genotypic data. Epidemiological data are required to inform an effective public health response. We conducted a household census-based random sampling serological survey, and a prospective hospital-based study of patients with cirrhosis and hepatocellular carcinoma (HCC) in Blantyre, Malawi. We tested participants with an HCV antigen/antibody ELISA (Monolisa, Bio-Rad), confirmed with PCR (GeneXpert, Cepheid) and used line immunoassay (Inno-LIA, Fujiribio) for RNA-negative participants. We did target-enrichment whole-genome HCV sequencing (NextSeq, Illumina). Among 96,386 censused individuals, we randomly selected 1661 people aged ≥16 years. Population-standardized HCV RNA prevalence was 0.2% (95% CI 0.1-0.5). Among 236 patients with cirrhosis and HCC, HCV RNA prevalence was 1.9% and 5.0%, respectively. Mapping showed that HCV RNA+ patients were from peri-urban areas surrounding Blantyre. Community and hospital HCV RNA+ participants were older than comparator HCV RNA-negative populations (median 53 vs 30 years for community, p = 0.01 and 68 vs 40 years for cirrhosis/HCC, p < 0.001). Endemic HCV genotypes (n = 10) were 4v (50%), 4r (30%) and 4w (10%). In this first census-based community serological study in Southern Africa, HCV was uncommon in the general population, was centred on peri-urban regions and was attributable for <5% of liver disease. HCV infection was observed only among older people, suggesting a historic mechanism of transmission. Genotype 4r, which has been associated with treatment failure with ledipasvir and daclatasvir, is endemic.

Differential localization and limited cytotoxic potential of duodenal CD8+ T cells

The duodenum is a major site of HIV persistence during suppressive antiretroviral therapy despite harboring abundant tissue-resident memory (Trm) CD8⁺ T cells. The role of duodenal Trm CD8⁺ T cells in viral control is still not well defined. We examined the spatial localization, phenotype, and function of CD8⁺ T cells in the human duodenal tissue from people living with HIV (PLHIV) and healthy controls. We found that Trm (CD69⁺CD103^hi) cells were the predominant CD8⁺ T cell population in the duodenum. Immunofluorescence imaging of the duodenal tissue revealed that CD103⁺CD8⁺ T cells were localized in the intraepithelial region, while CD103^–CD8⁺ T cells and CD4⁺ T cells were mostly localized in the lamina propria (LP). Furthermore, HIV-specific CD8⁺ T cells were enriched in the CD69⁺CD103^–/lo population. However, the duodenal HIV-specific CD8⁺ Trm cells rarely expressed canonical molecules for potent cytolytic function (perforin and granzyme B) but were more polyfunctional than those from peripheral blood. Taken together, our results show that duodenal CD8⁺ Trm cells possess limited perforin-mediated cytolytic potential and are spatially separated from HIV-susceptible LP CD4⁺ T cells. This could contribute to HIV persistence in the duodenum and provides critical information for the design of cure therapies.

Safety and Efficacy of a Typhoid Conjugate Vaccine in Malawian Children

BACKGROUND

Typhoid fever caused by multidrug-resistant H58 Salmonella Typhi is an increasing public health threat in sub-Saharan Africa.

METHODS

We conducted a phase 3, double-blind trial in Blantyre, Malawi, to assess the efficacy of Vi polysaccharide typhoid conjugate vaccine (Vi-TCV). We randomly assigned children who were between 9 months and 12 years of age, in a 1:1 ratio, to receive a single dose of Vi-TCV or meningococcal capsular group A conjugate (MenA) vaccine. The primary outcome was typhoid fever confirmed by blood culture. We report vaccine efficacy and safety outcomes after 18 to 24 months of follow-up.

RESULTS

The intention-to-treat analysis included 28,130 children, of whom 14,069 were assigned to receive Vi-TCV and 14,061 were assigned to receive the MenA vaccine. Blood culture-confirmed typhoid fever occurred in 12 children in the Vi-TCV group (46.9 cases per 100,000 person-years) and in 62 children in the MenA group (243.2 cases per 100,000 person-years). Overall, the efficacy of Vi-TCV was 80.7% (95% confidence interval [CI], 64.2 to 89.6) in the intention-to-treat analysis and 83.7% (95% CI, 68.1 to 91.6) in the per-protocol analysis. In total, 130 serious adverse events occurred in the first 6 months after vaccination (52 in the Vi-TCV group and 78 in the MenA group), including 6 deaths (all in the MenA group). No serious adverse events were considered by the investigators to be related to vaccination.

CONCLUSIONS

Among Malawian children 9 months to 12 years of age, administration of Vi-TCV resulted in a lower incidence of blood culture-confirmed typhoid fever than the MenA vaccine. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT03299426.).

Early Insights From Clinical Trials of Typhoid Conjugate Vaccine

Clinical trials of typhoid conjugate vaccine (TCV) are ongoing in 4 countries. Early data confirm safety, tolerability, and immunogenicity of typhoid conjugate vaccine, and early efficacy results are promising. These data support World Health Organization recommendations and planned country introductions. Forthcoming trial data will continue to inform programmatic use of typhoid conjugate vaccine.

Pediatric Laser Therapy in Pigmented Conditions

Advances in laser therapy have led to novel therapeutic approaches to common pediatric skin conditions. As a non-invasive alternative to surgical options, laser therapy is efficacious in treating a broad range of conditions, from vascular and pigmented lesions to tattoo and hair removal. This paper reviews the basic mechanics of laser therapy, its role in common pigmented pediatric dermatoses, and special considerations for this unique age group.

Temporal variability of glucocorticoid receptor activity is functionally important for the therapeutic action of fluoxetine in the hippocampus

Previous studies have shown inconsistent results regarding the actions of antidepressants on glucocorticoid receptor (GR) signalling. To resolve these inconsistencies, we used a lentiviral-based reporter system to directly monitor rat hippocampal GR activity during stress adaptation. Temporal GR activation was induced significantly by acute stress, as demonstrated by an increase in the intra-individual variability of the acute stress group compared with the variability of the non-stress group. However, the increased intra-individual variability was dampened by exposure to chronic stress, which was partly restored by fluoxetine treatment without affecting glucocorticoid secretion. Immobility in the forced-swim test was negatively correlated with the intra-individual variability, but was not correlated with the quantitative GR activity during fluoxetine therapy; this highlights the temporal variability in the neurobiological links between GR signalling and the therapeutic action of fluoxetine. Furthermore, we demonstrated sequential phosphorylation between GR (S224) and (S232) following fluoxetine treatment, showing a molecular basis for hormone-independent nuclear translocation and transcriptional enhancement. Collectively, these results suggest a neurobiological mechanism by which fluoxetine treatment confers resilience to the chronic stress-mediated attenuation of hypothalamic-pituitary-adrenal axis activity.

Mechanisms of potentiation of Angiotensin II-induced contractile response of isolated rat aorta by hydrogen peroxide and tert-butyryl hydroperoxide

Objective:

To study the mechanism involved in hydrogen peroxide (H₂O₂) or tert-butyl hydroperoxide (t-BHP)-induced potentiation of the Ang II-mediated contraction of isolated rat thoracic aorta.

Materials and Methods:

Thoracic aorta was isolated from the Sprauge dawley rats (300–320 gm), cut spirally and response to Ang II (5 × 10⁻⁸M) was taken in the absence and presence of H₂O₂ (10⁻⁶M) and t-BHP (10⁻⁵M). To explore the probable mechanism of H₂O₂ and t-BHP-induced potentiation of Ang II-mediated contractile response, different blockers such as losartan (AT₁ receptor blocker; 1 μM), catalase (H₂O₂ scavenger; 500 U/ml), lercanidipine (L-type calcium channel blocker; 1 μM), geinistein (tyrosine kinase inhibitor; 100 μM), and indomethacin (cyclo-oxygenase inhibitor; 10 μM) were used.

Results:

In spiral preparation of rat thoracic aorta, H₂O₂ (10⁻⁶M) and t-BHP (10⁻⁵M) did not produce the contraction as such. However, when they are added simultaneously with Ang II (5 × 10⁻⁸ M), they potentiated the contractile response of the Ang II. Catalase (500 U/ml) partially antagonized the Ang-II-induced contraction, as well as antagonized the potentiation induced by H₂O₂. Losartan (1 μM) and lercanidipine (1 μM) antagonized the Ang II-induced contractile response without affecting H₂O₂ (10⁻⁶M)-mediated potentiation. Geinistein (100 μM) antagonized H₂O₂ (10⁻⁶M)-mediated potentiation, but it slightly decreased the Ang II response. Losartan (1 μM) and lercanidipine (1 μM) and Geinistein (100 μM) antagonized the Ang II-induced contractile response but not t-BHP-mediated potentiation. Indomethacin antagonized t-BHP-mediated potentiation without affecting much of Ang II response.

Conclusion:

From the above-mentioned results, we can reasonably conclude that H₂O₂ and t-BHP potentiated the contraction induced by the Ang II. H₂O₂-induced potentiation of Ang II response may be mediated through tyrosine kinase activation and t-BHP through the activation of cyclo-oxygenase enzyme.

Drug loaded erythrocytes: as novel drug delivery system

Novel drug delivery systems are one of the widely used delivery systems. In the present scenario, amongst them, "Drug Loaded Erythrocytes" is one of the growing and potential systems for delivery of drugs and enzymes. Erythrocytes are biocompatible, biodegradable, possess long circulation half-life and can be loaded with variety of biologically active substances. Carrier erythrocytes are prepared by collecting blood sample from the organism of interest and separating erythrocytes from plasma. By using various physical and chemical methods the cells are broken and the drug is entrapped into the erythrocytes, finally they are resealed and the resultant carriers are then called "resealed erythrocytes". Surface modification with glutaraldehyde, antibodies, carbohydrates like sialic acid and biotinylation of loaded erythrocytes (biotinylated erythrocytes) is possible to improve their target specificity and to increase their circulation half-life. Upon reinjection the drug loaded erythrocytes serve as slow circulation depots, targets the drug to the reticuloendothelial system (RES), prevents degradation of loaded drug from inactivation by endogenous chemicals, attain steady state concentration of drug and decrease the side-effects of loaded drug. Nowadays, Nanoerythrosomes based drug delivery systems have excellent potential for clinical application.

Stress-induced changes in primate prefrontal profiles of gene expression

Stressful experiences that consistently increase cortisol levels appear to alter the expression of hundreds of genes in prefrontal limbic brain regions. Here, we investigate this hypothesis in monkeys exposed to intermittent social stress-induced episodes of hypercortisolism or a no-stress control condition. Prefrontal profiles of gene expression compiled from Affymetrix microarray data for monkeys randomized to the no-stress condition were consistent with microarray results published for healthy humans. In monkeys exposed to intermittent social stress, more genes than expected by chance appeared to be differentially expressed in ventromedial prefrontal cortex compared to monkeys not exposed to adult social stress. Most of these stress responsive candidate genes were modestly downregulated, including ubiquitin conjugation enzymes and ligases involved in synaptic plasticity, cell cycle progression and nuclear receptor signaling. Social stress did not affect gene expression beyond that expected by chance in dorsolateral prefrontal cortex or prefrontal white matter. Thirty four of 48 comparisons chosen for verification by quantitative real-time polymerase chain reaction (qPCR) were consistent with the microarray-predicted result. Furthermore, qPCR and microarray data were highly correlated. These results provide new insights on the regulation of gene expression in a prefrontal corticolimbic region involved in the pathophysiology of stress and major depression. Comparisons between these data from monkeys and those for ventromedial prefrontal cortex in humans with a history of major depression may help to distinguish the molecular signature of stress from other confounding factors in human postmortem brain research.

Glucocorticoid and mineralocorticoid receptor mRNA expression in squirrel monkey brain

Corticosteroids have been implicated in hippocampal atrophy in patients with severe psychiatric disorders, but little is known about receptor expression for corticosteroids in human or nonhuman primate brain. Both the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) were surveyed in this study of squirrel monkey brain using in situ hybridization histochemistry. Regions of high GR mRNA levels included CA1 and CA2 of hippocampus, dentate gyrus, paraventricular hypothalamus, lateral geniculate, lateral>medial amygdala, and cerebellum. Western analysis confirmed that GR immunoreactivity in squirrel monkey brain tissue most likely reflects the alpha isoform. Regions of high MR mRNA levels included all hippocampal pyramidal cell fields, dentate gyrus granule cell layer, lateral septum, medial>lateral amygdala, and to a lesser extent, cerebellum. Low levels of MR were also expressed in caudate and putamen. Receptor expression for corticosteroids in deep brain structures and the hippocampal formation was similar to that previously reported in rodents, but GR and MR mRNA were expressed at higher levels in squirrel monkey cerebral cortex. GR expression was evident in all cortical layers, particularly the pyramidal cell-rich layers II/III and V. MR expression was restricted to the more superficial cortical layers, and was only moderately represented in layer V. Laminar patterns were apparent in all regions of cortex for GR expression in squirrel monkeys, but low MR mRNA levels were found in dorsomedial prefrontal cortex (PFC). Different subregional distributions and distinctive laminar patterns suggest specialized functions or coordinated interactions between GR and MR mediated functions in primate PFC.

Impaired transactivation of the glucocorticoid receptor cloned from the Guyanese squirrel monkey

Squirrel monkeys are among a diverse group of New World primates that demonstrate unusually high levels of circulating corticosteroids and glucocorticoid receptor (GR) insensitivity. Recent evidence suggests that overexpression of an immunophilin impairs dexamethasone binding to GR in the Bolivian squirrel monkey (Saimiri boliviensis). Here we describe the cloning, expression, and functional characterization of GR from the closely related Guyanese squirrel monkey (S. sciureus). The cloned Guyanese squirrel monkey GR (gsmGR) cDNA closely resembles human GR (hGR) cDNA, and yields a high affinity dexamethasone binding receptor when expressed in COS-1 cells. Transactivation analysis of hGR and gsmGR expressed in CV-1 cells and cultured squirrel monkey kidney (SMK) cells indicates that: (1) SMK cells elaborate a functional high activity GR from human GR cDNA; (2) gsmGR is an order of magnitude less efficient than hGR at transactivation in CV-1 and SMK cells; and (3) maximal transactivation by gsmGR is attenuated in both cell lines. Glucocorticoid resistance in S. sciureus is at least partly attributable to a naturally occurring mutation in the GR gene that results in impaired GR transactivation.

Tetracycline up-regulates COX-2 expression and prostaglandin E2 production independent of its effect on nitric oxide

Tetracyclines (doxycycline and minocycline) augmented (one- to twofold) the PGE2 production in human osteoarthritis-affected cartilage (in the presence or absence of cytokines and endotoxin) in ex vivo conditions. Similarly, bovine chondrocytes stimulated with LPS showed (one- to fivefold) an increase in PGE2 accumulation in the presence of doxycycline. This effect was observed at drug concentrations that did not affect nitric oxide (NO) production. In murine macrophages (RAW 264.7) stimulated with LPS, tetracyclines inhibited NO release and increased PGE2 production. Tetracycline(s) and L-N-monomethylarginine (L-NMMA) (NO synthase inhibitor) showed an additive effect on inhibition of NO and PGE2 accumulation, thereby uncoupling the effects of tetracyclines on NO and PGE2 production. The enhancement of PGE2 production in RAW 264.7 cells by tetracyclines was accompanied by the accumulation of both cyclooxygenase (COX)-2 mRNA and cytosolic COX-2 protein. In contrast to tetracyclines, L-NMMA at low concentrations (< or = 100 microM) inhibited the spontaneous release of No in osteoarthritis-affected explants and LPS-stimulated macrophages but had no significant effect on the PGE2 production. At higher concentrations, L-NMMA (500 microM) inhibited NO release but augmented PGE2 production. This study indicates a novel mechanism of action of tetracyclines to augment the expression of COX-2 and PGE2 production, an effect that is independent of endogenous concentration of NO.

A novel mechanism of action of tetracyclines: effects on nitric oxide synthases

Tetracyclines have recently been shown to have "chondroprotective" effects in inflammatory arthritides in animal models. Since nitric oxide (NO) is spontaneously released from human cartilage affected by osteoarthritis (OA) or rheumatoid arthritis in quantities sufficient to cause cartilage damage, we evaluated the effect of tetracyclines on the expression and function of human OA-affected nitric oxide synthase (OA-NOS) and rodent inducible NOS (iNOS). Among the tetracycline group of compounds, doxycycline > minocycline blocked and reversed both spontaneous and interleukin 1 beta-induced OA-NOS activity in ex vivo conditions. Similarly, minocycline > or = doxycycline inhibited both lipopolysaccharide- and interferon-gamma-stimulated iNOS in RAW 264.7 cells in vitro, as assessed by nitrite accumulation. Although both these enzyme isoforms could be inhibited by doxycycline and minocycline, their susceptibility to each of these drugs was distinct. Unlike acetylating agents or competitive inhibitors of L-arginine that directly inhibit the specific activity of NOS, doxycycline or minocycline has no significant effect on the specific activity of iNOS in cell-free extracts. The mechanism of action of these drugs on murine iNOS expression was found to be, at least in part, at the level of RNA expression and translation of the enzyme, which would account for the decreased iNOS protein and activity of the enzyme. Tetracyclines had no significant effect on the levels of mRNA for beta-actin and glyceraldehyde-3-phosphate dehydrogenase nor on levels of protein of beta-actin and cyclooxygenase 2 expression. These studies indicate that a novel mechanism of action of tetracyclines is to inhibit the expression of NOS. Since the overproduction of NO has been implicated in the pathogenesis of arthritis, as well as other inflammatory diseases, these observations suggest that tetracyclines should be evaluated as potential therapeutic modulators of NO for various pathological conditions.

5'-Heterogeneity of the mineralocorticoid receptor messenger ribonucleic acid: differential expression and regulation of splice variants within the rat hippocampus

The mineralocorticoid receptor (MR) cDNA we previously isolated from the rat hippocampus differs from the clone isolated from the kidney at the 5'-untranslated (5'UT) region. The kidney clone (alpha MR mRNA) and the hippocampal clone (beta MR mRNA) possess unique 5'UT sequences of 220 and 300 nucleotides, respectively, but share an invariant peptide-coding domain and appear to encode an identical MR protein. The two mRNA variants may represent tissue-specific forms of the MR or may be coexpressed in the rat hippocampus along with other 5'UT variants. Here, we report that three mRNA subtypes were found in the hippocampus; their relative abundance was as follows: alpha = beta >> gamma. The three mRNA variants were differentially distributed within the hippocampal subfields, with the alpha form being highly enriched in CA2, dentate, the fasciculum cinereum, and the indusium griseum, whereas beta and gamma forms were evenly distributed through CA1-4. Adrenalectomy selectively increased alpha MR mRNA content, but the changes were restricted to CA1, CA2, and CA3 regions. We conclude that multiple MR mRNAs are differentially expressed in the rat hippocampus. The expression of alpha MR mRNA is specifically increased during adrenalectomy, suggesting that the increase in total MR mRNA content documented previously arises from a substantial increase in a single MR variant that elevates the total MR mRNA content, with the apparent elevation reflecting the average of regulated and unregulated transcripts. It is suggested from our data that a complex mechanism involving transcription and translation regulates MR expression in the rat hippocampus.

A bacterially expressed mineralocorticoid receptor is associated in vitro with the 90-kilodalton heat shock protein and shows typical hormone- and DNA-binding characteristics

A recombinant system was developed for generation of steroid-receptor complexes in vitro. The DNA- and steroid-binding domains of the rat mineralocorticoid receptor were expressed in Escherichia coli as a fusion protein with glutathione S-transferase. The identity of the expressed recombinant protein was confirmed by Western blot analysis. Protein preparations purified by affinity chromatography, avoiding the use of detergents or high ionic strength buffers, exhibited negligible steroid binding. However, after incubation of these preparations with rabbit reticulocyte lysate, known to promote the association of isolated steroid receptors with heat shock proteins, the [3H]aldosterone-binding activity gradually increased. This temperature-dependent effect reached a maximum after 1 h at 30 degrees C and was favored by ATP supplementation (Bmax = 22 +/- 3 pmol/mg of protein). The apparent Kd value for aldosterone (0.6 +/- 0.2 nM) and the steroid-binding specificity of the recombinant protein were in accordance with those reported for the native mineralocorticoid receptor. The sedimentation and DNA-cellulose-binding characteristics of the radioactive complexes were also in agreement with those reported for the native heteromeric receptor. Complexes sedimented at 8.9 +/- 0.2 or 4.2 +/- 0.2 S in sucrose gradients containing 20 mM sodium molybdate or 0.4 M KCl, respectively. Monoclonal antibody 8D3 against the 90-kDa heat shock protein (hsp90) was able to bind to the 8.9S complexes, increasing its sedimentation coefficient. Treatment of the complexes with 100 mM sodium thiocyanate, known to activate the native receptor to a DNA-binding state, caused a 79% increase in DNA-cellulose binding over the control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-occupational pneumoconiosis at high altitude villages in central Ladakh

An epidemiological survey was carried out to investigate the occurrence of non-occupational pneumoconiosis in Ladakh, where there are no mines or industries. The clinicoradiological investigations of 449 randomly selected subjects from three villages showed typical cases of pneumoconiosis associated with progressive massive fibrosis and egg shell calcification of hilar glands. The prevalence of pneumoconiosis in these three villages was 2.0%, 20.1% and 45.3% and it corresponded with the severity of dust storms and the use of chimneys in the kitchens. The dust concentrations in the kitchens with no provision for a chimney were very high. The free silica content of the storms was between 60 and 70%. Exposure to free silica from dust storms and soot from domestic fuels are suggested as causes of these cases of pneumoconiosis.

Cloning and analysis of the rat gamma-glutamyltransferase gene

We have isolated and characterized a complete structural gene encoding the enzyme gamma-glutamyltransferase ((5-glutamyl)-peptide:amino acid 5-glutamyltransferase; EC 2.3.2.2). The gene contains 8 exons and spans approximately 12 kilobases. Ras-transformed rat liver epithelial cells and rat kidney express RNAs which differ in length by approximately 0.3 kilobase pair. Comparison of the genomic sequence with kidney gamma GT cDNA sequence indicates that the first exon is noncoding, and nuclease protection and primer extension data have identified a potential kidney transcription start site (defined as +1) for this exon. The site is not associated with a TATA box, but there are two CCAAT boxes (-136 and -599) and two sites (-101 and -746) containing the consensus sequences to which the transcription factor SP1 is known to bind. There is also a sequence at -453 (TGTGGTTG) that is highly homologous to the core sequence (TGTGG(T)3-5G) of SV40 and polyoma viral enhancers.

Direct evidence that the glucocorticoid receptor binds to hsp90 at or near the termination of receptor translation in vitro

We have translated the rat glucocorticoid receptor in both reticulocyte lysate and in wheat germ extract. Receptor synthesized in the reticulocyte lysate is immunoadsorbed by the 8D3 monoclonal antibody directed against the 90-kDa heat shock protein (hsp90) and it has a normal ability to bind glucocorticoid in a high affinity manner. Although the wheat germ extract synthesizes the full length receptor, the receptor is not immunoadsorbed by 8D3 and we cannot demonstrate high affinity steroid binding. Receptor synthesized by the reticulocyte lysate can be immunoadsorbed by antibody directed against hsp90 as soon as the translation product is full length, suggesting that the receptor becomes associated with hsp90 late during translation or immediately at the termination of translation. When newly synthesized receptor is bound with steroid and incubated at 25 degrees C, it is converted to a form that binds to DNA. This study provides direct evidence that association of hsp90 with the glucocorticoid receptor is a very early event and that the newly formed heteromeric receptor-hsp90 complex is fully competent to undergo transformation.

Localization and regulation of glucocorticoid and mineralocorticoid receptor messenger RNAs in the hippocampal formation of the rat

Messenger RNAs coding for glucocorticoid (GR) and mineralocorticoid (MR) receptor proteins were localized to discrete subfields of the hippocampal formation by in situ hybridization histochemistry, using cRNA probes of approximately equivalent specific activity. Both GR and MR mRNAs were present in all subfields examined; GR mRNA was of greatest abundance in CA1, while MR mRNA was most densely labeled in CA3. In all subfields examined, MR mRNA was considerably more abundant than GR mRNA. Removal of circulating glucocorticoids by adrenalectomy precipitated an up-regulation of GR mRNA in subfields CA1-2 and the dentate gyrus, which was reversed by dexamethasone replacement. High doses of dexamethasone significantly down-regulated GR mRNA in CA3. In contrast, adrenalectomy produced significant up-regulation of MR mRNA only in subfield CA1-2. The data indicate that steroid receptor mRNAs are differentially distributed in hippocampus, and that sensitivity to steroids occurs within defined structural domains of the hippocampal formation.

Molecular cloning of a mineralocorticoid (type I) receptor complementary DNA from rat hippocampus

Rat brain expresses two types of corticosteroid-binding proteins. The type I receptor binds corticosterone with high affinity and is structurally related to the kidney mineralocorticoid receptor (MR), while the type II or classical glucocorticoid receptor binds corticosterone with lower affinity and displays an in vivo preference for dexamethasone. Here we describe the isolation and characterization of a cDNA coding for the MR, from a rat hippocampus cDNA library, by low stringency hybridization to radiolabeled human glucocorticoid receptor cDNA. The nucleotide and deduced amino acid sequence for rat hippocampal MR displays extensive homology to a MR cDNA isolated from human kidney, suggesting that they are orthologous genes. Southern analysis suggests that there is only one gene for the MR, and in vitro expression of the receptor generates a high affinity corticosterone-binding protein. These data provide evidence to support the contention that a single gene gives rise to the MR in renal tissues and type I receptors in the brain.

Characterization of pro-opiomelanocortin cDNA from the Old World monkey, Macaca nemestrina

An observation from high-pressure liquid chromatography (HPLC) suggesting that monkey beta-endorphin (BE) was chemically different from human or rat BE was investigated by determining the cDNA sequence for the monkey pro-opiomelanocortin (POMC) precursor. A full-length cDNA for POMC was isolated from a Macaca nemestrina whole pituitary cDNA library. The longest open reading frame predicts a 264-residue polypeptide exhibiting the basic structure of POMC that is closely homologous to the human counterpart. The monkey BE sequence apparently diverged from the human sequence after the latter had made the His-27 to Tyr-27 change but prior to the Gln-31 to Glu-31 transition, leaving it more hydrophobic than rat or human BE, consistent with its chromatography on reverse-phase HPLC. Comparison of the monkey POMC precursor with those of other species highlights conserved domains, presumably reflecting regions of physiological activity that await elucidation.

Characterization of the dexamethasone-induced inhibitor of plasminogen activator in HTC hepatoma cells

Incubation of HTC rat hepatoma cells with the synthetic glucocorticoid dexamethasone rapidly inhibits plasminogen activator (PA) activity secondary to the induction of a specific acid-stable inhibitor of plasminogen activation (Cwikel, B. J., Barouski-Miller, P.A., Coleman, P.L., and Gelehrter, T.D. (1984) J. Biol. Chem. 259, 6847-6851). We have further characterized this inhibitor with respect to its interaction with both urokinase and tissue plasminogen activator, and its protease specificity. The HTC PA inhibitor rapidly inhibits urokinase and tissue plasminogen activator with an apparent second-order rate constant of 3-5 x 10(7) M-1 X s-1. The inhibitor forms stable covalent complexes with both urokinase and tissue plasminogen activator, with which plasmin, trypsin, and factor Xa apparently do not compete. Complex formation is saturable and requires the active site of the PA. The mass of the inhibitor-PA complex is 50,000 daltons greater than that of PA alone, consistent with an Mr for the PA inhibitor of 50,000 as demonstrated directly by reverse fibrin autography. The HTC PA inhibitor does not inhibit thrombin and differs in its kinetic and biochemical properties from protease nexin.

A note on estimation of food spoilage yeasts by measurement of adenosine triphosphate (ATP) after growth at various temperatures

The growth at 4 degrees, 10 degrees and 15 degrees C of six psychrotrophic yeasts isolated from foods was compared using total viable counts and ATP measurement. A linear relationship (r greater than or equal to 0.97) was obtained between log10 (number of viable yeasts) and log10 (ATP content) of cultures grown at these temperatures. This relationship was not temperature-dependent. The results are discussed and their significance for the rapid estimation of yeasts in foods is considered.

Investigation of the mechanism of decreased sensitivity of the rat seminal vesicle to norepinephrine by lithium

Li+ is reported to reduce sensitivity of alpha-adrenergic receptors to NE. The present investigation was designed to investigate the mechanism of this decreased sensitivity on the rat isolated seminal vesicle. In innervated preparations, 1.35 X 10(-3) M Li+ (i) shifted the concentration-response curves of NE, methoxamine, ACh and BaCl2 to the right and reduced their maximum responses; (ii) antagonized the leftward shift and the enhancement of maximum responses to NE by cocaine (2.9 X 10(-4) M), and (iii) reduced only the maximum responses to KCl. In denervated preparations, 1.35 X 10 (-3) M Li+ shifted the concentration response curve of NE to the left without any change in the maximum responses. The antagonistic effects of Li+ on maximal responses to NE, ACh and KCl observed in innervated preparations were significantly increased in Ca++-free medium. Li+ (1.35 X 10(-3) M) increased NE uptake by the seminal vesicle significantly. It is concluded that decreased sensitivity of the seminal vesicle to NE by Li+ could be due to an increase in the uptake of NE and to a nonspecific postsynaptic spasmolytic action.