ABSTRACT
Despite its role in treating the most dominant non-communicable diseases worldwide, the global workforce of oral and maxillofacial (OM) surgeons is not well-characterized. To address the current deficit in understanding of the global OM surgeon workforce and to elevate oral and maxillofacial surgery (OMS) in the global health discourse, we join other surgical specialties in evaluating global surgical capacity with a descriptive analysis of the distribution of OM surgeons worldwide. A mixed-methods study was implemented using a combination of literature review, in-country contacts, internet searches, and survey data. The survey was distributed globally from January to June 2022. Data regarding OM surgeon workforce estimates were obtained for 104 of 195 United Nations-recognized countries (53.3%). Among countries with available estimates, the median global workforce density was 0.518 OM surgeons per 100,000 population. Twenty-eight countries (26.9%) were reported to have two or fewer OM surgeons. The median OM surgeon workforce density for low-income countries was 0.015 surgeons per 100,000 population, compared to 1.087 surgeons per 100,000 population in high-income countries. low and middle-income countries countries have the least workforce density as well as the least data coverage. More work is needed to better understand the capacity of the global OM surgeon workforce and access to OMS care.
ABSTRACT
The emerging field of global oral and maxillofacial surgery (OMS) aims to improve worldwide access to safe, timely, and affordable OMS care. However, there exists a dearth of literature thoroughly detailing the scope of academic global OMS collaborations between high-income countries (HICs) and low- and/or lower middle-income countries (LICs/LMICs). This scoping review was performed to characterize the landscape of global academic OMS collaborations between HICs and LICs/LMICs. A five-stage methodological framework was used. Academic global OMS collaborations from 1996 to 2020 were identified via an electronic database and grey literature review. A total 1318 articles were identified on December 17, 2020. Following the application of inclusion and exclusion criteria, 71 articles describing 81 unique global OMS academic collaborations were included in the final analysis. The most common HIC was the United States (44.4%); the majority of LIC/LMICs were within Africa (45.8%). Of the total interventions, 89.6% improved LIC/LMIC capacity development, and surgical (43.8%) interventions were the most common. By serving as a central report on current and past academic collaborations in global OMS, this review helps identify areas in need of surgical capacity building, lays the foundation for future research efforts on the topic, and serves as a resource for individuals aiming to become involved in global OMS.
Subject(s)
Surgery, Oral , Developing Countries , Humans , United StatesABSTRACT
Colorectal cancer (CRC) is the third most common cancer globally. CRC risk is increased by obesity, and by its lifestyle determinants notably physical inactivity and poor nutrition. Obesity results in increased inflammation and oxidative stress which cause genomic damage and contribute to mitochondrial dysregulation and CRC risk. The mitochondrial dysfunction associated with obesity includes abnormal mitochondrial size, morphology and reduced autophagy, mitochondrial biogenesis and expression of key mitochondrial regulators. Although there is strong evidence that increased adiposity increases CRC risk, evidence for the effects of intentional weight loss on CRC risk is much more limited. In model systems, energy depletion leads to enhanced mitochondrial integrity, capacity, function and biogenesis but the effects of obesity and weight loss on mitochondria in the human colon are not known. We are using weight loss following bariatric surgery to investigate the effects of altered adiposity on mitochondrial structure and function in human colonocytes. In summary, there is strong and consistent evidence in model systems and more limited evidence in human subjects that over-feeding and/or obesity result in mitochondrial dysfunction and that weight loss might mitigate or reverse some of these effects.
Subject(s)
Colorectal Neoplasms , Mitochondria , Obesity , Weight Loss , Bariatric Surgery , Humans , Mitochondria/chemistry , Mitochondria/metabolism , Mitochondria/physiology , Risk FactorsABSTRACT
Mycobacterium avium subspecies paratuberculosis (MAP), as an obligate intracellular bacterium, causes paratuberculosis (Johne's disease) in ruminants. Plus, MAP has consistently been isolated from Crohn's disease (CD) lesions in humans; a notion implying possible direct causative effect for MAP in CD development. Infections caused by MAP are refractory to treatment and in many cases the treatment does not easily resolve the infection. Studying the molecular mechanisms of host-pathogen interaction is helpful in identifying possible drug targets. In this line, it has already been shown that in macrophages infected with various bacteria, including mycobacteria, micro RNA 21 (miR-21) is upregulated, a change that results in diminished macrophages clearance ability and favours pathogens survival within the cells. However, the molecular mechanism(s) by which the intracellular bacteria induce miR-21 expression is not known. In order to verify possible effects from epigenetic changes induced by intracellular bacteria, we studied the cytosine methylation changes at the transcription start regions of miR-21 in THP-1 macrophages infected with MAP. For this purpose, genomic DNA was extracted from infected cells and the methylation status at the region of interest was evaluated by bisulfite conversion method. Our work showed that MAP directs de-methylation of the cystosines at CpG di-nucleotides in this region, while non-CpG cytosines of this region did not show significant changes. Interestingly, the CpG cytosines that were differentially methylated in the infected macrophages occur at the binding sites of the transcription factors already known to regulate miR-21 expression.
ABSTRACT
BACKGROUND AND PURPOSE: Candidaalbicans is the most common cause of candidal infections. Various studies have shown drug resistance among C. albicans isolates; thus, it is necessary to discover replacement treatments for Candida infections. In this study, we aimed to compare the effects of different essential oils against azoles-resistant and azoles-susceptible isolates. MATERIALS AND METHODS: Twenty fluconazole-resistant and 20 susceptible C. albicans isolates obtained from oral, vaginal, and cutaneous tissues of patients with candidiasis were evaluated. The efficacy and minimum inhibitory concentrations (MICs) of Zataria multiflora, Geranium herbarum,Lavendula officinalis,Cuminum, cyminum,Allium heamanthoides, and Artemisia sieberi essential oils against C. albicans were determined on the basis of a reference method for broth microdilution susceptibility testing of yeasts as suggested by Clinical and Laboratory Standards Institute (CLSI, M27-S4). After inoculation, incubation, and subculturation, the MICs were determined through comparison with the control. RESULTS: The obtained MICs for Zataria multiflora, Geranium herbarum, Artemisia sieberi, Allium heamanthoides, Cumminum cyminum, and Lavendula officinalis were 0.1-0.25 µl/ml (mean: 0.155 µl/ml), 0.625-1.66 µl/ml (mean: 0.93 µl/ml) 0.833-2.0 µl/ml (mean: 1.21 µl/ml), 0.1-0.25 µl/ml (mean: 0.155 µl/ml), 2-4 µl/ml (mean: 3.1 µl/ml), and 1.5-3.0 µl/ml (mean: 2.4 µl/ml), respectively. The results showed that Zataria multiflora and Allium heamanthoides essential oils were more efficient than other essential oils against Candida species. There were no significant differences between various Candida strains in terms of susceptibility to the essential oils. In addition, there were no significant differences in the MICs of these essential oils against the azoles-resistant and azoles-susceptible isolates. CONCLUSION: In this study, the anti-Candida effects of six essential oils against both azoles-resistant and azoles-susceptible isolates were similar. Given the documented resistance of different Candida species to synthetic and chemical antifungals, these essential oils are effective replacement treatments for cutaneous and mucosal Candida infections, especially in resistant or recurrent cases.
ABSTRACT
BACKGROUND: The severe burden imposed by frailty and disability in old age is a major challenge for healthcare systems in low- and middle-income countries alike. The current study aimed to provide estimates of the prevalence of frailty and disability in older adult populations and to examine their relationship with socioeconomic factors in six countries. METHODS: Focusing on adults aged 50+ years, a frailty index was constructed as the proportion of deficits in 40 variables, and disability was assessed using the World Health Organization Disability Assessment Schedule (WHODAS 2.0), as part of the Study on global AGEing and adult health (SAGE) Wave 1 in China, Ghana, India, Mexico, Russia and South Africa. RESULTS: This study included a total of 34,123 respondents. China had the lowest percentages of older adults with frailty (13.1%) and with disability (69.6%), whereas India had the highest percentages (55.5% and 93.3%, respectively). Both frailty and disability increased with age for all countries, and were more frequent in women, although the sex gap varied across countries. Lower levels of both frailty and disability were observed at higher levels of education and wealth. Both education and income were protective factors for frailty and disability in China, India and Russia, whereas only income was protective in Mexico, and only education in South Africa. CONCLUSIONS: Age-related frailty and disability are increasing concerns for older adult populations in low- and middle-income countries. The results indicate that lower levels of frailty and disability can be achieved for older people, and the study highlights the need for targeted preventive approaches and support programs.
Subject(s)
Chronic Disease/epidemiology , Disabled Persons/statistics & numerical data , Aged , Aged, 80 and over , Developing Countries , Disability Evaluation , Female , Global Health , Health Services for the Aged , Humans , Male , Middle Aged , Prevalence , Risk Factors , Socioeconomic Factors , World Health OrganizationABSTRACT
Non-communicable diseases are now the number one cause of disabilities and loss of life expectancy. Among them, chronic respiratory conditions constitute a major class. The burden of chronic respiratory diseases is generally increasing across the globe, and asthma and chronic obstructive pulmonary disease (COPD) are among the main causes of mortality and morbidity. However, the direct and indirect costs of these conditions vary across jurisdictions. This article reports on recent estimates of the costs of asthma and COPD, with a focus on comparing disease burden across different regions. Overall, there is tremendous variation in per capita annual costs of asthma and COPD. However, the methodology of the cost-of-illness studies is also vastly different, making it difficult to associate differences in reported costs to differences in the true burden of asthma and COPD. Suggestions are provided towards improving the validity and comparability of future studies.
Subject(s)
Asthma/economics , Pulmonary Disease, Chronic Obstructive/economics , Global Health , Health Expenditures , HumansABSTRACT
Whispering gallery modes (WGMs) within microsphere cavities enable highly sensitive label-free detection of changes in the surrounding refractive index. This detection modality is of particular interest for biosensing applications. However, the majority of biosensing work utilizing WGMs to date has been conducted with resonators made from either silica or polystyrene, while other materials remain largely uninvestigated. By considering characteristics such as the quality factor and sensitivity of the resonator, the optimal WGM sensor design can be identified for various applications. This work explores the choice of resonator refractive index and size to provide design guidelines for undertaking refractive index biosensing using WGMs.
ABSTRACT
BACKGROUND: To determine the impact of silent coronary artery disease (CAD), in different levels of glucose regulation at baseline, i.e., those with normal fasting glucose/normal glucose tolerance (NFG/NGT), pre-diabetic and newly diagnosed diabetes mellitus (NDM), on cardiovascular disease (CVD) and total mortality in Iranian populations. METHODS: The study population included 1809 individuals, aged ≥50years, free of CVD at baseline with a median follow-up of 12.1years. To explore the risk of CVD and mortality associated with the presence of silent CAD (as defined by Minnesota coding criteria for baseline electrocardiogram (ECG) in the absence of a history of CVD) in each of the glucose regulation categories, multivariate adjusted hazard ratios (HRs) were calculated for the presence of silent CAD, compared to the corresponding non-silent CAD counterpart, as reference. RESULTS: During follow-up 382 CVD (321 coronary heart disease) and 208 deaths (91 CVD mortality) occurred. Among the female population, the presence of silent CAD, independent of traditional risk factors, significantly increased the risk of CVD for population with NFG/NGT [2.40 (1.33-4.35)] and pre-diabetes [HR: 2.04 (1.14-3.63)]; however, in the male population the risk was significant for CVD [3.04 (1.53-6.05)] and mortality events [2.60 (1.22-5.56)] in the NDM population and marginally significant for mortality events in NFG/NGT. CONCLUSION: Different strategies should be considered for silent CAD in males and females with different levels of glucose regulation. It might be justified that screening ECG for prevention of CVD events should be considered mainly among non-diabetic women and men with NDM.
Subject(s)
Blood Glucose/metabolism , Coronary Artery Disease/epidemiology , Forecasting , Prediabetic State/epidemiology , Risk Assessment , Coronary Artery Disease/blood , Coronary Artery Disease/complications , Female , Follow-Up Studies , Glucose Tolerance Test , Humans , Iran/epidemiology , Male , Middle Aged , Prediabetic State/blood , Prediabetic State/complications , Prospective Studies , Risk Factors , Survival Rate/trendsABSTRACT
AIM: Currently in the UK the standard surgical practice for the management of perforated sigmoid diverticulitis is a Hartmann's procedure. There have been a number of recent publications on the use of laparoscopic peritoneal lavage for perforated sigmoid diverticulitis, as an alternative to the emergency Hartmann's procedure, with its associated morbidity and mortality. We aim to review the current literature on this topic. METHOD: A search was made on the electronic database MEDLINE from PubMed, EMBASE and the Cochrane library. The keywords 'diverticulitis', 'perforated' and 'laparoscopy' were searched for in the titles and abstracts without language restrictions. Further studies were identified from searches on Google Scholar, as well as manual searches through reference lists of the relevant studies found. All included studies were quality assessed. RESULTS: Twelve relevant studies were included. A total of 301 patients were reported, with a mean age of 57 years. All were non-randomized studies. The majority of patients were of Hinchey classification III. All were treated with intravenous antibiotics followed by laparoscopic lavage and insertion of intra-abdominal/pelvic drains. The mean conversion rate was 4.9% and mean length of hospital stay was 9.3 days. The mean complication rate was 18.9% and the overall mortality rate was 0.25%. Subsequent elective resections with primary anastamosis were performed in 51% of patients and the majority were completed laparoscopically. CONCLUSION: Laparoscopic peritoneal lavage for perforated sigmoid diverticulitis appears to be a potentially effective and more conservative alternative to a Hartmann's procedure. Randomized control trials are needed to better evaluate its role.
Subject(s)
Diverticulitis, Colonic/therapy , Intestinal Perforation/therapy , Peritoneal Lavage , Sigmoid Diseases/therapy , Anti-Bacterial Agents/therapeutic use , Diverticulitis, Colonic/complications , Humans , Intestinal Perforation/etiology , Laparoscopy , Sigmoid Diseases/complicationsABSTRACT
Accumulating evidence suggests that pregnancy does not protect women from mental illness. The aim of this study was to assess the prevalence, sociodemographic correlates, and the risks factors for perinatal depression and anxiety. Five hundred ninety women between 28th and the 32nd gestational weeks were recruited and submitted to a sociodemographic, obstetric, and psychological interview. The Edinburgh Postnatal Depression Scale (EPDS) and the state-trait anxiety inventory (STAI-Y) were also administered in antenatal period and 3 months postnatally. The Structured Clinical Interview for DSM-IV (SCID-I) was used to diagnose mood and anxiety disorders. Three months after delivery, EPDS was administered by telephone interview. Women with an EPDS score ≥10 were 129 in antenatal period (21.9%) and 78 in postnatal period (13.2%). During pregnancy 121 women (20.5%) were positive for STAI-Y state and 149 women (25.3%) for STAI-Y trait. The most important risk factors for antenatal depression are: foreign nationality, conflictual relationship with family and partner, and lifetime psychiatric disorders. The principal risk factors for postnatal depression are: psychiatric disorders during pregnancy and artificial reproductive techniques. Psychiatric disorders, during and preceding pregnancy, are the strongest risk factors for antenatal state and trait anxiety. Antenatal depressive and anxiety symptoms appear to be as common as postnatal symptoms. These results provide clinical direction suggesting that early identification and treatment of perinatal affective disorders is particularly relevant to avoid more serious consequences for mothers and child.
Subject(s)
Anxiety Disorders/epidemiology , Depressive Disorder/epidemiology , Pregnancy Complications/epidemiology , Pregnancy Complications/psychology , Adult , Comorbidity , Female , Humans , Interviews as Topic , Italy/epidemiology , Perinatal Care , Pregnancy , Prevalence , Psychiatric Status Rating Scales , Risk Factors , Young AdultABSTRACT
The aim of this study was to investigate the dose-related effects of fenitrothion (FNT) on the liver and kidney. The study was conducted on 8-week-old male Wistar rats that were divided into four groups (three experimental groups and one control group) and were treated orally with different doses (25, 50, 100 mg/kg) of FNT for 28 consecutive days. After treatment, the rats were anesthetized with ether and liver and kidney samples were taken for histological studies. The results showed that the histopathological changes in the liver were mainly represented by parenchymatous degeneration of hepatocytes with mild necrosis, leukocytic infiltration in the portal area, severe congestion, and hemorrhage. These changes were dose dependent. Marked tubular dilation, hydropic degeneration in tubular epithelium, moderate congestion, and hemorrhage in the cortical and medulla part of the kidney were recorded. Histopathologic examination of the liver and kidney indicated a significant injury only in rats receiving 100 mg/kg FNT.
Subject(s)
Fenitrothion/toxicity , Insecticides/toxicity , Kidney/pathology , Liver/pathology , Administration, Oral , Analysis of Variance , Animals , Dose-Response Relationship, Drug , Leukemic Infiltration/chemically induced , Male , Necrosis/chemically induced , Rats , Rats, WistarABSTRACT
The absorption and fluorescence sensing properties of liquid-immersed exposed-core microstructured optical fibers are explored for the regime where these structures act as supported nanowires with direct access to the sensing environment. For absorption-based sensing we demonstrate that the amount of power propagating in the sensing region of the exposed-core fiber can compete with that of traditional MOFs. For fluorescence-based sensing, we see that in addition to the enhanced fluorescence capture efficiency already predicted for small-core, high refractive index contrast fibers, an improvement of up to 29% can be gained by using liquid-immersed exposed-core fibers. Additionally, calculation of the losses associated with interfaces between filled and unfilled sections predict significant benefit in using high refractive index substrate glasses for liquid-immersed exposed-core fiber sensing. This work demonstrates that, for fiber dimensions of interest, the exposed-core fiber is an attractive new sensor technology.
Subject(s)
Fiber Optic Technology/instrumentation , Models, Theoretical , Transducers , Computer Simulation , Equipment Design , Equipment Failure Analysis , Light , Miniaturization , Optical Fibers , Scattering, Radiation , SolutionsABSTRACT
About 2-4% of adults suffer from obstructive sleep apnea (OSA), which is the most common sleep-related breathing disorder (SRBD). Repetitive obstructions of the upper airway mean that it is associated with hypertension and an elevated cardio- and cerebrovascular morbidity, which can be lowered by means of effective therapy. These patients cannot be treated correctly unless they are identified early in the course of the condition. Therefore, this study evaluated the use of the microMESAM screening device (known up to December 2005 as the "ApneaLink") in 61 patients in whom SRBD was suspected. The device proved reliable and practical in application.
Subject(s)
Diagnosis, Computer-Assisted/instrumentation , Mass Screening/instrumentation , Monitoring, Physiologic/instrumentation , Rheology/instrumentation , Sleep Apnea Syndromes/diagnosis , Spirometry/instrumentation , Diagnosis, Computer-Assisted/methods , Equipment Design , Equipment Failure Analysis , Female , Humans , Male , Mass Screening/methods , Middle Aged , Monitoring, Physiologic/methods , Polysomnography/instrumentation , Polysomnography/methods , Reproducibility of Results , Rheology/methods , Sensitivity and Specificity , Spirometry/methodsABSTRACT
The nitrate reductase of the hyperthermophilic archaeon Pyrobaculum aerophilum was purified 137-fold from the cytoplasmic membrane. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the enzyme complex consists of three subunits with apparent molecular weights of 130,000, 52,000, and 32,000. The enzyme contained molybdenum (0.8-mol/mol complex), iron (15.4-mol/mol complex) and cytochrome b (0.49-mol/mol complex) as cofactors. The P. aerophilum nitrate reductase distinguishes itself from nitrate reductases of mesophilic bacteria and archaea by its very high specific activity using reduced benzyl viologen as the electron donor (V(max) with nitrate, 1,162 s(-1) (326 U/mg); V(max) with chlorate, 1,348 s(-1) (378 U/mg) [assayed at 75 degrees C]). The K(m) values for nitrate and chlorate were 58 and 140 microM, respectively. Azide was a competitive inhibitor and cyanide was a noncompetitive inhibitor of the nitrate reductase activity. The temperature optimum for activity was > 95 degrees C. When incubated at 100 degrees C, the purified nitrate reductase had a half-life of 1.5 h. This study constitutes the first description of a nitrate reductase from a hyperthermophilic archaeon.
Subject(s)
Nitrate Reductases/metabolism , Thermoproteaceae/enzymology , Enzyme Stability , Hydrogen-Ion Concentration , Kinetics , Molecular Weight , Molybdoferredoxin , Nitrate Reductase , Nitrate Reductases/chemistry , Nitrate Reductases/isolation & purification , Protein Subunits , TemperatureABSTRACT
Prolonged infusions of 17beta-estradiol reduce fetal pulmonary vascular resistance (PVR), but the effects of endogenous estrogens in the fetal pulmonary circulation are unknown. To test the hypothesis that endogenous estrogen promotes pulmonary vasodilation at birth, we studied the hemodynamic effects of prolonged estrogen-receptor blockade during late gestation and at birth in fetal lambs. We treated chronically prepared fetal lambs with ICI-182,780 (ICI, a specific estrogen-receptor blocker, n = 5) or 1% DMSO (CTRL, n = 5) for 7 days and then measured pulmonary hemodynamic responses to ventilation with low- and high-fraction inspired oxygen (FI(O(2))). Treatment with ICI did not change basal fetal PVR or arterial blood gas tensions. However, treatment with ICI abolished the vasodilator response to ventilation with low FI(O(2)) [change in PVR -30 +/- 6% (CTRL) vs. +10 +/- 13%, (ICI), P < 0.05] without reducing the vasodilator response to ventilation with high FI(O(2)) [change in PVR, -73 +/- 3% (CTRL) vs. -77 +/- 4%, (ICI); P = not significant]. ICI treatment reduced prostacyclin synthase (PGIS) expression by 33% (P < 0.05) without altering expression of endothelial nitric oxide synthase or cyclooxygenase-1 and -2. In situ hybridization and immunohistochemistry revealed that PGIS is predominantly expressed in the airway epithelium of late gestation fetal lambs. We conclude that prolonged estrogen-receptor blockade inhibits the pulmonary vasodilator response at birth and that this effect may be mediated by downregulation of PGIS. We speculate that estrogen exposure during late gestation prepares the pulmonary circulation for postnatal adaptation.
Subject(s)
Estradiol/administration & dosage , Estrogen Antagonists/administration & dosage , Prenatal Exposure Delayed Effects , Pulmonary Circulation/drug effects , Receptors, Estrogen/antagonists & inhibitors , Animals , Animals, Newborn , Blotting, Western , Cyclooxygenase 1 , Cyclooxygenase 2 , Cytochrome P-450 Enzyme System/metabolism , Drug Administration Schedule , Estradiol/analogs & derivatives , Female , Fetus/blood supply , Fetus/drug effects , Fetus/physiology , Fulvestrant , Hemodynamics/drug effects , Infusions, Intra-Arterial/methods , Intramolecular Oxidoreductases/metabolism , Isoenzymes/metabolism , Lung/drug effects , Lung/embryology , Lung/enzymology , Nitric Oxide/metabolism , Nitric Oxide/pharmacology , Nitric Oxide Synthase/metabolism , Nitric Oxide Synthase Type III , Organ Specificity , Pregnancy , Prostaglandin-Endoperoxide Synthases/metabolism , Pulmonary Artery/embryology , Pulmonary Artery/physiology , Pulmonary Circulation/physiology , Pulmonary Ventilation/drug effects , Sheep , Vasodilation/drug effects , Vasodilation/physiologyABSTRACT
Pyrobaculum aerophilum, a hyperthermophilic archaeon, can respire either with low amounts of oxygen or anaerobically with nitrate as the electron acceptor. Under anaerobic growth conditions, nitrate is reduced via the denitrification pathway to molecular nitrogen. This study demonstrates that P. aerophilum requires the metal oxyanion WO42- for its anaerobic growth on yeast extract, peptone, and nitrate as carbon and energy sources. The addition of 1 &mgr;M MoO42- did not replace WO42- for the growth of P. aerophilum. However, cell growth was completely inhibited by the addition of 100 &mgr;M MoO42- to the culture medium. At lower tungstate concentrations (0.3 &mgr;M and less), nitrite was accumulated in the culture medium. The accumulation of nitrite was abolished at higher WO42- concentrations (<0.7 &mgr;M). High-temperature enzyme assays for the nitrate, nitrite, and nitric oxide reductases were performed. The majority of all three denitrification pathway enzyme activities was localized to the cytoplasmic membrane, suggesting their involvement in the energy metabolism of the cell. While nitrite and nitric oxide specific activities were relatively constant at different tungstate concentrations, the activity of nitrate reductase was decreased fourfold at WO42- levels of 0.7 &mgr;M or higher. The high specific activity of the nitrate reductase enzyme observed at low WO42- levels (0.3 &mgr;M or less) coincided with the accumulation of nitrite in the culture medium. This study documents the first example of the effect of tungstate on the denitrification process of an extremely thermophilic archaeon. We demonstrate here that nitrate reductase synthesis in P. aerophilum occurs in the presence of high concentrations of tungstate.
ABSTRACT
The physiological mechanisms that regulate epithelial gene expression during enterocyte migration and differentiation are still poorly understood. The present study has used a combination of quantitative in situ hybridisation, immunohistochemistry and enzyme cytochemistry to examine epithelial cell differentiation in rabbit small intestine. We have measured and compared the levels of mRNA and enzyme activity of the enterocyte brush border markers alkaline phosphatase, amino-peptidase N and lactase in normal villus epithelia and in epithelial cells exposed directly to the Peyer's patch immune environment. All three genes appeared to be expressed in parallel, but in each epithelial population examined, the pattern of gene expression was different. The level of these mRNAs was markedly reduced in Peyer's patch-associated epithelia, this being most pronounced in the follicle-associated epithelium, compared with normal villi. The activities of alkaline phosphatase and aminopeptidase N approximated the expression of their genes, whereas additional post-transcriptional events were shown to clearly contribute to the level of lactase activity in these tissues. These findings demonstrate that the reduced brush border hydrolase activity in Peyer's patch tissue that has been observed previously, is due to a down-regulation of epithelial gene expression in this location. These observations have been used to discuss epithelial differentiation in Peyer's patch tissue and the possible role of local immune factors in regulating such events.
Subject(s)
Gene Expression Regulation , Intestinal Mucosa/physiology , Intestine, Small/physiology , Peyer's Patches/physiology , Alkaline Phosphatase/genetics , Animals , Blotting, Northern , CD13 Antigens/genetics , Histocytochemistry , Immunohistochemistry , In Situ Hybridization , Lactase-Phlorizin Hydrolase/genetics , RNA, Messenger/metabolism , RabbitsABSTRACT
The effect of shell calcification and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on calbindin-D28K (previously known as vitamin D-dependent calcium-binding protein) and calbindin mRNA was investigated in the intestine and eggshell gland (ESG) of juvenile female chicks, laying hens and non-laying female birds with active gonads. Increasing amounts of 1,25-(OH)2D3 were fed to laying hens and juvenile birds treated with oestradiol to develop the ESG. The intestinal concentration of calbindin was increased 30-fold by 1,25-(OH)2D3 in chicks treated with oestradiol and fed a vitamin D-deficient diet. In these same animals, 1,25-(OH)2D3 had no effect on the formation of calbindin mRNA or calbindin in the ESG even though fully viable 1,25-(OH)2D3 receptors are present in this tissue. In laying birds fed adequate amounts of vitamin D3, intestinal, but not ESG, calbindin was increased by the addition of 1,25-(OH)2D3 to the diet. At the onset of egg production the concentrations of calbindin and calbindin mRNA were increased in the intestine and ESG. This increase occurred within the period of calcification of the first egg, through a process unaffected by vitamin D. Calcification of the first egg increased the concentration of calbindin in the ESG by eight- to tenfold, although the concentration of calbindin mRNA was increased by only two- to threefold. These results suggest that the induction of calbindin synthesis by 1,25-(OH)2D3 or by the egg calcification process is associated with an increase in the concentration of calbindin mRNA in the ESG and intestine.(ABSTRACT TRUNCATED AT 250 WORDS)