Value of intraoperative monitoring of the trigeminal nerve in detection of a superiorly displaced facial nerve during surgery for large vestibular schwannomas.

The aim of this study was to investigate the role of trigeminal and facial nerve monitoring in the early identification of a superiorly (anterior and superior (AS)) displaced facial nerve. This prospective study included 24 patients operated for removal of large vestibular schwannomas (VS). The latencies of the electromyographic (EMG) events recorded from the trigeminal and facial nerve innervated muscles after mapping the superior surface of the tumor were analyzed. The mean latency of the recorded compound muscle action potential (CMAP) from the masseter muscle was 3.6 ± 0.5 ms and of the peripherally transmitted responses by volume conduction from the frontalis, o. oculi, nasalis, o. oris, and mentalis muscles was 4.6 ± 0.9, 4.1 ± 0.7, 3.9 ± 0.4, 4.3 ± 0.8, and 4.5 ± 0.6 ms, respectively, after trigeminal nerve stimulation in 24 (100%) patients (pattern I response). In 6 (25%) patients, the mean latency of CMAP on the masseter was 3.3 ± 0.3 ms, and the latencies of the CMAP from the frontalis, o. oculi, nasalis, o. oris, and mentalis muscles were 6.5 ± 1.3, 5.0 ± 1.5, 7.5 ± 1.3, 7.4 ± 0.6, and 7.0 ± 1.5 ms, respectively, longer than those of the peripherally transmitted responses (p = 0.002, p = 0.001, p < 0.001, and p = 0.015, respectively) indicating simultaneous stimulation of both nerves (pattern II response). All patients with this response were later confirmed to have an AS-displaced facial nerve. Recognizing the response resulting from simultaneous stimulation of both the facial and trigeminal nerves is important to help early identification of an AS-displaced facial nerve before it is visible in the surgical field and to avoid misleading information by confusing this pattern for a pure trigeminal nerve response.

Hepatitis C virus infection and risk factors in health-care workers at Ain Shams University Hospitals, Cairo, Egypt.

The objectives of this study were to document the background prevalence and incidence of HCV infection among HCWs in Ain Shams University Hospitals in Cairo and analyse the risk factors for HCV infection. A cross-sectional survey was conducted in 2008 among 1770 HCWs. Anti-HCV prevalence was age-standardized using the Cairo population. A prospective cohort was followed for a period of 18 months to estimate HCV incidence. The crude anti-HCV prevalence was 8.0% and the age-standardized seroprevalence was 8.1%. Risk factors independently associated with HCV seropositivity were: age, manual worker, history of blood transfusions and history of parenteral anti-schistosomiasis treatment. The estimated incidence of HCV infection was 7.3 per 1000 person-years. HCWs in this setting had a similar high HCV seroprevalence as the general population of greater Cairo.

Surgery for traumatic facial nerve paralysis: does intraoperative monitoring have a role?

The use of intraoperative facial nerve (FN) monitoring during surgical decompression of the FN is underscored because surgery is indicated when the FN shows more than 90 % axonal degeneration. The present study proposes including intraoperative monitoring to facilitate decision taking and provide prognostication with more accuracy. This prospective study was conducted on ten patients presenting with complete FN paralysis due to temporal bone fracture. They were referred after variable time intervals for FN exploration and decompression. Intraoperative supramaximal electric stimulation (2-3 mA) of the FN was attempted in all patients both proximal and distal to the site of injury. Postoperative FN function was assessed using House-Brackmann (HB) scale. All patients had follow-up period ranging from 7 to 42 months. Three different patterns of neurophysiological responses were characterized. Responses were recorded proximal and distal to the lesion in five patients (pattern 1); only distal to the lesion in two patients (pattern 2); and neither proximal nor distal to the lesion in three patients (pattern 3). Sporadic, mechanically elicited EMG activity was recorded in eight out of ten patients. Patients with pattern 1 had favorable prognosis with postoperative function ranging between grade I and III. Pattern 3 patients showing no mechanically elicited activity had poor prognosis. Intraoperative monitoring affects decision taking during surgery for traumatic FN paralysis and provides prognostication with sufficient accuracy. The detection of mechanically elicited EMG activity is an additional sign predicting favorable outcome. However, absence of responses did not alter surgeon decision when the nerve was found evidently intact.

Carbon based sensors for air quality monitoring networks; middle east perspective.

IoT-based Sensors networks play a pivotal role in improving air quality monitoring in the Middle East. They provide real-time data, enabling precise tracking of pollution trends, informed decision-making, and increased public awareness. Air quality and dust pollution in the Middle East region may leads to various health issues, particularly among vulnerable populations. IoT-based Sensors networks help mitigate health risks by offering timely and accurate air quality data. Air pollution affects not only human health but also the region's ecosystems and contributes to climate change. The economic implications of deteriorated air quality include healthcare costs and decreased productivity, underscore the need for effective monitoring and mitigation. IoT-based data can guide policymakers to align with Sustainable Development Goals (SDGs) related to health, clean water, and climate action. The conventional monitor based standard air quality instruments provide limited spatial coverage so there is strong need to continue research integrated with low-cost sensor technologies to make air quality monitoring more accessible, even in resource-constrained regions. IoT-based Sensors networks monitoring helps in understanding these environmental impacts. Among these IoT-based Sensors networks, sensors are of vital importance. With the evolution of sensors technologies, different types of sensors materials are available. Among this carbon based sensors are widely used for air quality monitoring. Carbon nanomaterial-based sensors (CNS) and carbon nanotubes (CNTs) as adsorbents exhibit unique capabilities in the measurement of air pollutants. These sensors are used to detect gaseous pollutants that includes oxides of nitrogen and Sulphur, and ozone, and volatile organic compounds (VOCs). This study provides comprehensive review of integration of carbon nanomaterials based sensors in IoT based network for better air quality monitoring and exploring the potential of machine learning and artificial intelligence for advanced data analysis, pollution source identification, integration of satellite and ground-based networks and future forecasting to design effective mitigation strategies. By prioritizing these recommendations, the Middle East and other regions, can further leverage IoT-based systems to improve air quality monitoring, safeguard public health, protect the environment, and contribute to sustainable development in the region.

Circulating miR-206, miR-181b, and miR-21 as promising biomarkers in hypothyroidism and their relationship to related hyperlipidemia and hepatic steatosis.

Background: Thyroid hormones (THs) signaling has profound effects on many physiological processes. The regulation of THs signaling in various tissues involves the action of microRNAs (miRNAs) on thyroid deiodinases and receptors. THs regulate the expression of certain miRNAs and their target messenger RNAs (mRNAs) in various tissues and cells. The modulation of miRNA levels by THs affects their functions in processes such as liver lipid metabolism, skin physiology, and muscle and heart performance. Aim: This research aimed to investigate miR-181b, miR-206, and miR-21 in the serum of patients with subclinical and overt hypothyroidism to determine their possible role in the diagnosis of the disease and their relationship to clinical disorders related to hypothyroidism. Methods: This study included ninety participants, divided evenly into three groups as follows: patients with overt hypothyroidism diagnosed clinically, radiologically, and by investigation, subclinical hypothyroid patients, and healthy volunteers. The patients had a thorough medical history and underwent a clinical examination. Laboratory tests included plasma cholesterol, LDL, HDL, TGs, liver and renal function tests, CBC, fasting insulin, HOMA-IR, HbA1c, TSH, and free T4. The serum levels of miR-21, miR-206, and miR-181b were measured using qRT-PCR. Results: miR-206 and miR-181b levels were higher in the subclinical group, followed by the hypothyroid and control groups. For miR-21, there was a significantly lower mean value in both the hypothyroid and subclinical groups than in the control group, with no difference between the two groups. Both miR-206 and miR-181b showed a significant negative association with albumin and free T4 levels and a significant direct association with GGT, ALT, AST, creatinine, uric acid, TGs, TC, LDL, TSH, thyroid volume, and CAP score. The same correlation pattern was observed for miR-181b, except that it was not significantly correlated with the TGs. For miR-21 levels, there was a significant positive correlation with albumin, free T4 level, and kPa score and a negative correlation with GGT, ALT, AST, creatinine, uric acid, HOMA-IR, HbA1c, TC, LDL, TSH, and CAP score. Cases with F1 kPa score and S2 CAP scores had significantly higher averages for miR-206 and miR-181b, with a p-value of 0.05. Moreover, miR-21 levels were significantly lower in the S2 CAP score group. Conclusion: These miRNAs (miR-206, miR-181b, and miR-21) may be used as diagnostic biomarkers for hypothyroidism. They may be used as therapeutic targets to control dyslipidemia and hepatic steatosis during hypothyroid disease.

Towards realistic estimates of HCV incidence in Egypt.

Accurate incidence estimates are essential for quantifying hepatitis C virus (HCV) epidemic dynamics and monitoring the effectiveness of public health programmes, as well as for predicting future burden of disease and planning patient care. In Egypt, the country with the largest HCV epidemic worldwide, two modelling studies have estimated age-specific incidence rates that, applied to the age pyramid, would correspond to more than 500 000 Egyptians getting infected annually. This is in contrast to figures of the Egyptian Ministry of Health and Population that estimates new infections to be approximately 100 000 per year. We performed new analyses of nationwide data to examine the modelling assumptions that led to these estimates. Thus, we found that the key assumption of these models of a stationary epidemic is invalid. We propose an alternate approach to estimating incidence based on analysing cohort data; we find that the number of annual new infections is <150 000.

Prevalence of hepatitis B and C virus infections and their related risk factors in Libya: a national seroepidemiological survey.

A high prevalence of hepatitis B (HBV) and C virus (HCV) infections has been reported among specific patient groups in Libya; a survey was thus designed to determine the extent of the problem at the national level. A multi-stage sampling design covering all administrative areas of Libya was applied, covering > 65,000 individuals of all age groups. All subjects gave a blood sample and completed a questionnaire on demographic and risk behaviour data. The prevalence of HBV surface antigen (HBsAg) and anti-HCV were 2.2% and 1.3% respectively. The prevalence of anti-HCV increased with age, rising gradually after age 30 years, in contrast to a stable prevalence of HBsAg in all age groups 10+ years. Age-adjusted risk factors for HCV infection were previous hospitalization, surgical operations, previous blood transfusions and intravenous drug use; for HBV infection only family exposure or contact with HBV case were identified.

Larvicidal potential, toxicological assessment, and molecular docking studies of four Egyptian bacterial strains against Culex pipiens L. (Diptera: Culicidae).

Mosquito control in Egypt depends on applying chemical synthetic pesticides that impact negatively on human health and the environment as well as the development of antibiotic and chemical resistance. This study aims to control the 3rd and 4th instars of Culex pipiens larvae using four bacterial strains. According to Phenotypic and molecular identification, the four isolates were identified as Bacillus subtilis MICUL D2023, Serratia marcescens MICUL A2023, Streptomyces albus LARVICID, and Pseudomonas fluorescens MICUL B2023. All strains were deposited in GenBank under accession numbers OQ764791, OQ729954, OQ726575, and OQ891356, respectively. Larvicidal activity of all microbial strain metabolites against a field strain of C. pipiens explored low LC50 results and reached its lowest values on the 3rd day with values of 6.40%, 38.4%, and 46.33% for P. fluorescens, S. albus, and S. marcescens, respectively. In addition, metabolites of P. fluorescence were more toxic than those of S. albus, followed by S. marcescens. B. subtilis shows no larvicidal effect on both field and lab mosquito strains. Microscopic alterations of 3rd and 4th instars showed toxic effects on different body parts (thorax, midgut, and anal gills), including losing external hairs, abdominal breakage, and larvae shrinkage, as well as different histological malformations in the digestive tract, midgut, and cortex. GC-MS analysis detected 51, 30, and 32 different active compounds from S. albus, S. marcescens, and P. fluorescens, respectively. GC detected 1, 2-BENZEA2:A52NEDICARBOXYLIC ACID, 2-Cyclohexene-1-carboxylic-acid-5-2-butenyl-methyl ester, and 3 octadecahydro2R3S4Z9Z-11R-12S from S. albus, S. marcesens, and P. fluorescens, respectively. Total protein, Total carbohydrate, and Acetylcholine esterase activity indicated significantly low levels on the 3rd day. All strain metabolites were safe against HSF cell lines. The docking results confirmed the role of the produced metabolites as larvicidal agents and Acetylcholine esterase inhibition. Such a problem need more studies on applying more and more natural pesticides.

HCV burden of infection in Egypt: results from a nationwide survey.

Egypt is the country with the largest hepatitis C virus (HCV) epidemic in the world. In 2008, a Demographic Health Survey (DHS) was carried out in Egypt, providing for the first time a unique opportunity for HCV antibody testing on a nationwide representative sample of individuals. Consenting individuals answered a questionnaire on socio-demographic characteristics and iatrogenic exposures, before providing a blood sample for HCV antibody testing by enzyme-linked immunosorbent assay. Factors independently associated with HCV infection were examined through multivariate logistic regression models. Of 12 780 eligible subjects aged 15-59 years, 11 126 (87.1%) agreed to participate and provided a blood sample. HCV antibody prevalence nationwide was 14.7% (95% CI 13.9-15.5%) in this age group. HCV antibody prevalence gradually increased with age, reaching, in the 50-59 years age group, 46.3% and 30.8% in males and females, respectively. It was higher in males compared to females (17.4% versus 12.2%, respectively, P < 0.001), and in rural compared to urban areas (18.3% versus 10.3%, respectively, P < 0.001). In multivariate analysis, age, male sex, poverty, past history of intravenous anti-schistosomiasis treatment, blood transfusion, and living outside of the Frontier Governorates were all significantly associated with an increased risk of HCV infection. In addition, in urban areas, lack of education and being circumcised for females were associated with an increased risk of HCV infection. This study confirmed on a nationwide representative sample the very high HCV antibody prevalence in Egypt. It stresses the urgent need for strengthening prevention efforts, and bringing down the costs of antiviral drugs for countries like Egypt, where the people in the most precarious situations are also those most likely to be infected by the virus.

Reproducibility of liver stiffness measurements in hepatitis C virus (HCV)-infected patients in Egypt.

Elastometry has demonstrated good accuracy, but little is known about its reproducibility. The aim of this study was to assess the intra- and inter-operator reproducibility of liver stiffness measurement among hepatitis C virus (HCV)-infected patients in Egypt. The study was conducted among HCV-infected patients referred for treatment evaluation in two hepatitis treatment centres of Cairo. Two operators took liver stiffness measurement two times per patient the same day. Intra- and inter-reproducibility were estimated by different methods: Bland and Altman graphics, variation coefficient, intraclass correlation coefficient and Kappa coefficient; 7.1 kPa was used as the threshold of significant (≥F2) fibrosis whenever needed. Fifty-eight patients were included in the study, and 216 measurements were taken. Failure rate was 7% and associated with overweight. For a value of 7.1 kPa, the inter-operator 95% limits of agreement were estimated at ±2.88 kPa. Intra- and inter-operator coefficients of variation ranged between 11% and 15%, intraclass correlation coefficients [95% confidence interval] between 0.94 [0.86-0.97] and 0.97 [0.95-0.99], and Kappa coefficients between 0.65 [0.44-0.88] and 0.92 [0.81-1.00]. The reliability of liver stiffness measurement is questionable when considering the decision to initiate antiviral therapy because of the percentage of discordance between measurements is notable, especially in the intermediate fibrosis stages.

HCV iatrogenic and intrafamilial transmission in Greater Cairo, Egypt.

OBJECTIVES: To document hepatitis C virus (HCV) intrafamilial transmission and assess its relative importance in comparison to other current modes of transmission in the country with the largest HCV epidemic in the world. HCV intrafamilial transmission was defined as HCV transmission among relatives living in the same household. DESIGN: Case-control study. Cases were adult patients with acute hepatitis C diagnosed in two 'fever hospitals' of Cairo. Controls were adult patients with acute hepatitis A diagnosed in the same two hospitals, and family members of cases. All consenting household members of cases provided blood for HCV serological and RNA testing. Homology of viral sequences (NS5b region) within households was used to ascertain HCV intrafamilial transmission. Exposures at risk for HCV during the 1-6 months previous to onset of symptoms were assessed in all cases and controls. RESULTS: From April 2002 to June 2007, 100 cases with acute hepatitis C, and 678 controls (416 household members and 262 patients with acute hepatitis A) were recruited in the study. Factors independently associated with HCV infection and their attributable fractions (AFs) were the following: having had a catheter (OR=5.0, 95% CI=1.4 to 17.8; AF=6.7%), an intravenous perfusion (OR=5.8, 95% CI=2.5 to 13.3; AF=20.1%), stitches (OR=2.0, 95% CI=1.3 to 6.6; AF=10.7%), gum treatment (OR=3.7, 95% CI=1.1 to 11.9; AF=3.8%) and being illiterate (OR=2.4, 95% CI=1.4 to 4.4). Of the 100 cases, 18 had viraemic HCV-infected household members. Three long-married (>15 years) couples were infected with virtually identical sequences and none of the three index patients reported any exposure at risk, suggesting HCV intra-familial transmission. CONCLUSION: While three new HCV infections out of 100 could be linked to intra-familial transmission, parenteral iatrogenic transmission (dental care included) was accountable for 34.6% of these new infections. Thus, the relative contribution of intrafamilial transmission to HCV spread seems to be limited.

Dissection of familial correlations in hepatitis C virus (HCV) seroprevalence suggests intrafamilial viral transmission and genetic predisposition to infection.

OBJECTIVE: Unsafe injections and transfusions used during treatments are considered to be responsible for many cases of transmission of hepatitis C virus (HCV) in developing countries, but cannot account for a substantial proportion of present infections. The aim of the present work was to investigate familial clustering of HCV infection in a population living in a highly endemic area. DESIGN, SETTING AND PARTICIPANTS: A large seroepidemiological survey was conducted on 3994 subjects (age range, 2-88 years) from 475 familial clusters in an Egyptian rural area. Epidemiological methods appropriate for the analysis of correlated data were used to estimate risk factors and familial dependences for HCV infection. A phylogenetic analysis was conducted to investigate HCV strain similarities within and among families. MAIN OUTCOME MEASURES: HCV familial correlations adjusted for known risk factors, similarities between viral strains. RESULTS: Overall HCV seroprevalence was 12.3%, increasing with age. After adjustment for relevant risk factors, highly significant intrafamilial resemblances in HCV seroprevalence were obtained between father-offspring (odds ratio (OR) = 3.4 (95% confidence interval (CI), 1.8 to 6.2)), mother-offspring (OR = 3.8 (95% CI, 2.5 to 5.8)), and sibling-sibling (OR = 9.3 (95% CI, 4.9 to 17.6)), while a weaker dependence between spouses (OR = 2.2 (95% CI, 1.3 to 3.7)) was observed. Phylogenetic analysis showed greater HCV strain similarity between family members than between unrelated subjects, indicating that correlations can be explained, in part, by familial sources of virus transmission. In addition, refined dissection of correlations between first-degree relatives supported the role of host genes predisposing to HCV infection. CONCLUSIONS: Current HCV infection in endemic countries has a strong familial component explained, at least partly, by specific modes of intrafamilial viral transmission and by genetic predisposition to infection.

Complementary and alternative medicine for lowering blood lipid levels: A systematic review of systematic reviews.

BACKGROUND: The aim of this article is to summarize and critically evaluate the evidence from systematic reviews (SRs) of complementary and alternative medicine (CAM) for lowering blood lipid levels (BLL). METHODS: Eight electronic databases were searched until March 2016. Additionally, all the retrieved references were inspected manually for further relevant papers. Systematic reviews were considered eligible, if they included patients of any age and/or gender with elevated blood lipid levels using any type of CAM. We used the Oxman and AMSTAR criteria to critically appraise the methodological quality of the included SRs. RESULTS: Twenty-seven SRs were included in the analyses. The majority of the SRs were of high methodological quality (mean Oxman score=4.81, SD=4.88; and the mean AMSTAR score=7.22, SD=3.38). The majority of SRs (56%) arrived at equivocal conclusions (of these 8 were of high quality); 7 SRs (37%) arrived at positive conclusions (of these 6 were of high quality), and 2 (7%) arrived at negative conclusions (both were of high quality). There was conflicting evidence regarding the effectiveness of garlic; and promising evidence for yoga. CONCLUSIONS: To conclude, the evidence from SRs evaluating the effectiveness of CAM in lowering BLL is predominantly equivocal and confusing. Several limitations exist, such as variety of doses and preparations, confounding effects of diets and lifestyle factors, or heterogeneity of the primary trials among others.

Antagonist-occupied human progesterone B-receptors activate transcription without binding to progesterone response elements and are dominantly inhibited by A-receptors.

When antagonist-occupied steroid receptors have agonist-like effects, the clinical consequences are grave. We present evidence that human progesterone B-receptors (hPRB) when occupied by progesterone antagonists, inappropriately activate transcription by an unusual mechanism that does not require the canonical progesterone response element (PRE). In HeLa cells cotransfected with a PRE-tk-chloramphenicol acetyltransferase reporter and a hPRB expression vector, strong transcription is seen not only when receptors are activated by the agonist R5020, but also in the presence of the three antiprogestins, RU486, ZK112993, and ZK98299. Human PRB occupied by ZK98299 do not bind to a PRE, suggesting that the transcriptional stimulation is independent of DNA binding. Indeed, a tk-chloramphenicol acetyltransferase promoter-reporter lacking the PRE loses transcriptional activation by the agonist, but retains transactivation by the three antagonists. The PRE-independent antagonist-induced transcription requires that hPRB have an intact DNA-binding domain, but hPR target gene specificity is not required, because a hPRB mutant that binds an estrogen response element still activates transcription. It appears that antagonist-occupied hPR activate transcription without binding to a PRE, perhaps by interacting with tethering proteins instead. Even a gene that is not a normal progesterone target could be aberrantly activated. Human cells contain equimolar amounts of hPRB and the N-terminally truncated natural isotype, hPRA. Unlike hPRB, hPRA are not transcriptionally activated by progesterone antagonists. We, therefore, tested the effects of antagonists when the two receptor isotypes are coexpressed and found that A-receptors can annul the inappropriate transcription by B-receptors. Thus, when both receptor forms are present, the hPRA phenotype is dominant. Moreover, pure hPRB/hPRA heterodimers, produced by fos/jun leucine zipper domain-hPR chimeras, also have the inactive transcriptional phenotype of hPRA. Our studies suggest not only that the two hPR isotypes are functionally quite different, but also that some of the agonist-like transcriptional effects of antagonist-occupied B-receptors proceed through novel mechanisms.

Structure and upstream region characterization of the human gene encoding rod photoreceptor cGMP phosphodiesterase alpha-subunit.

Rod photoreceptor cGMP phosphodiesterase (PDE6) is a three-subunit (a, b, g2) enzyme that functions to reduce intracellular cytoplasmic cGMP levels, an integral feature of the phototransduction cascade of vision. To allow assessment of the potential for defects in the gene encoding the alpha-subunit (PDE6A) to cause visual dysfunction, and to begin to dissect the basis for photoreceptor-specific expression of this gene, we have characterized the structural gene and upstream region. The human PDE6A gene consists of 22 exons spanning about 60 kb with the intron/exon junctions highly conserved in comparison to the mouse and human PDE6B genes. Using ribonuclease protection and primer extension assays, a predominant transcription start point (tsp) was identified 120 bp upstream of the initiator ATG. To begin functional analysis of the PDE6A promoter, approx 4 kb of sequence were determined upstream of the tsp. Comparison of this upstream sequence with an approximately 500 bp sequence upstream of the mouse Pde6a gene revealed five distinct segments of identity all within 100 bp upstream of the human PDE6A tsp. A TATA box adjacent to a photoreceptor-specific RET1-like binding site, an SP1 site, and two novel putative cis-element sequences were found. A consensus initiator element sequence is present at the tsp. Additionally, within a 2.5-kb segment beginning 900 bp upstream of the tsp two Alu, a MIR, an L1, and two MER repetitive elements were found. Electrophoretic mobility shift assays generate a retina-specific bandshift using a 322-bp fragment containing the putative promoter region or a multimer of the RET1-like site. DNA footprinting assays revealed footprints over the primary transcription startpoint and the RET1-like and TATA box regions. These results indicate that a 220-bp segment of the PDE6A gene upstream region is important for tissue-specific expression.

13th meeting of the Scientific Group on Methodologies for the Safety Evaluation of Chemicals (SGOMSEC): alternative testing methodologies and conceptual issues.

Substantial world-wide resources are being committed to develop improved toxicological testing methods that will contribute to better protection of human health and the environment. The development of new methods is intrinsically driven by new knowledge emanating from fundamental research in toxicology, carcinogenesis, molecular biology, biochemistry, computer sciences, and a host of other disciplines. Critical evaluations and strong scientific consensus are essential to facilitate adoption of alternative methods for use in the safety assessment of drugs, chemicals, and other environmental factors. Recommendations to hasten the development of new alternative methods included increasing emphasis on the development of mechanism-based methods, increasing fundamental toxicological research, increasing training on the use of alternative methods, integrating accepted alternative methods into toxicity assessment, internationally harmonizating chemical toxicity classification schemes, and increasing international cooperation to develop, validate, and gain acceptance of alternative methods.

Effect of long-term ovariectomy and estrogen replacement on the expression of estrogen receptor gene in female rats.

OBJECTIVE: Estrogen exerts a wide variety of actions involving many target tissues. We studied the effects of long-term ovariectomy (OVX) and OVX with 17beta-estradiol treatment (OVXE2) on the level of estrogen receptor (ER) gene expression in target tissues of female rats. DESIGN: Three groups of Sprague-Dawley female rats were utilized in this study: sham operated (SO), OVX and OVXE2. METHODS: SO and OVX were performed 2 weeks before starting the 17beta-estradiol treatment. All groups were maintained on liquid diet for 12 weeks from the time of estradiol treatment. Total RNA was prepared from the tissues of the rats and relative quantitative reverse transcription PCR was utilized to compare the ER alpha-subtype (ERalpha) mRNA level in the three groups for each target tissue. RESULTS: Following long-term OVX, the levels of ERalpha expression showed a significant increase in the uterus, kidney and cerebral cortex and no significant change in the liver, cerebellum, brainstem, heart and thoracic and abdominal aorta compared with their SO levels. On the other hand, a 12-week treatment of OVX rats with 17beta-estradiol restored the previously upregulated ERalpha mRNA to near SO levels except for the liver where the 17beta-estradiol treatment resulted in a significant increase in the ERalpha mRNA level compared with that in SO rats. CONCLUSIONS: We conclude that the regulation of ERs by its ligand is tissue specific.

The leucine zippers of c-fos and c-jun for progesterone receptor dimerization: A-dominance in the A/B heterodimer.

Human progesterone receptors (hPR) exist as two isoforms: 120 kDa B-receptors (hPRB) and N-terminally truncated 94 kDa A-receptors (hPRA). When transfected separately, each isoform exhibits different transcriptional properties that are ligand- and promoter-specific. In human target tissues, both receptor isoforms are present, so that a mixture of three dimeric species, A/A, A/B, and B/B, bind to DNA at progesterone response elements (PRE), and regulate transcription. To study the transcriptional phenotype of pure A/B heterodimers uncontaminated by A/A or B/B homodimers, we exploited the property of the leucine zipper (zip) domains of fos and jun, to form pure heterodimers. Chimeric constructs were made linking the zip of either c-fos or c-jun to the C-terminus of hPRB or hPRA (hPR-zip) to produce A-fos, B-fos, A-jun or B-jun. To determine whether the A- or B-isoform is functionally dominant in the A/B heterodimer, cells expressing hPR-zip chimeras were treated with the progestin antagonist RU486, which produces opposite transcriptional effects with the two isoforms. Gel mobility shift and immune co-precipitation assays show that in the presence of RU486 only pure heterodimers form between A-fos/B-jun or A-jun/B-fos, and bind DNA at PREs. Thus, in these pairs, interactions between the extrinsic fos/jun zipper domains override interactions between the intrinsic hPR dimerization domains. We find that under these conditions, antagonist-occupied B-zip homodimers stimulate transcription, while antagonist-occupied A-zip homodimers are inhibitory, and that pure A/B zip heterodimers have the inhibitory transcriptional phenotype of the A-zip homodimers. We conclude that, in pure heterodimers, A-receptors are dominant negative inhibitors of B-receptors. Additionally, the pure PR-zip heterodimers, unlike wild-type receptors, bind a PRE in the absence of hormone but do not activate transcription. Thus, PR dimerization and PRE binding are necessary but, without hormone, not sufficient to activate transcription.

Laser light-scattering study of the toxic effects of methylmercury on sperm motility.

An in vitro study was designed using the laser light-scattering technique to obtain further information on the dose-effect relationship of methylmercury on sperm motility. The technique provided a quantitative evaluation of sperm swimming speed. Semen samples were collected from normal male Macaca fascicularis monkeys by anal electroejaculation. Methylmercury was added to aliquots of sperm suspensions in BWW medium in doses of 10, 5, 2, and 1 ppm. After 3 hours, the relative speed was 35%, 59%, 69%, and 92% of the corresponding controls at doses of 10, 5, 2, and 1 ppm, respectively. The percentage of motile spermatozoa decreased significantly at 10 ppm. By microscopic observation abnormal motility was detected at 5 and 10 ppm, especially after 20 to 40 minutes. Head movement increased from side to side, and many spermatozoa developed coiled tails. The technique proved useful for defining the dose-effect relationship of methylmercury and sperm swimming speed.