SCP1, a 356 023 bp linear plasmid adapted to the ecology and developmental biology of its host, Streptomyces coelicolor A3(2)

The sequencing of the entire genetic complement of Streptomyces coelicolor A3(2) has been completed with the determination of the 365,023 bp sequence of the linear plasmid SCP1. Remarkably, the functional distribution of SCP1 genes somewhat resembles that of the chromosome: predicted gene products/functions include ECF sigma factors, antibiotic biosynthesis, a gamma-butyrolactone signalling system, members of the actinomycete-specific Wbl class of regulatory proteins and 14 secreted proteins. Some of these genes are among the 18 that contain a TTA codon, making them targets for the developmentally important tRNA encoded by the bldA gene. RNA analysis and gene fusions showed that one of the TTA-containing genes is part of a large bldA-dependent operon, the gene products of which include three proteins isolated from the spore surface by detergent washing (SapC, D and E), and several probable metabolic enzymes. SCP1 shows much evidence of recombinational interactions with other replicons and transposable elements during its history. For example, it has two sets of partitioning genes (which may explain why an integrated copy of SCP1 partially suppressed the defective partitioning of a parAB-deleted chromosome during sporulation). SCP1 carries a cluster of probable transfer determinants and genes encoding likely DNA polymerase III subunits, but it lacks an obvious candidate gene for the terminal protein associated with its ends. This may be related to atypical features of its end sequences.

Water quality management in the Kaoping River watershed, Taiwan

The Kaoping River basin is the largest and the most intensively used river basin in Taiwan. It is 171 km long and drains a catchment of more than 3,250 km2. Based on the current water quality analysis, the Kaoping River is heavily polluted. Concern about the deteriorating condition of the river led the Government of Taiwan to amend the relevant legislation and strengthen the enforcement of the discharge regulations to effectively manage the river and control the pollution. Investigation results demonstrate that both point and non-point source pollutants are now the causes of biochemical oxygen demand (BOD), nutrients, and pathogens in the river. The main water pollution sources are livestock wastewater from hog farms, municipal wastewater, industrial wastewater, non-point source (NPS) pollutants from agricultural areas, and leachate from riverbank landfills. The current daily BOD, NH3-N, and TP loadings to Kaoping River are 74,700, 39,400, and 5,100 kg, respectively. However, the calculated BOD, NH3-N, and TP carrying capacities are 27,700, 4,200, and 600 kg per day. To protect public health and improve the river water quality, a comprehensive management and construction strategy is proposed. The proposed strategy includes the following measures to meet the calculated river carrying capacity: (1) a hog ban in the entire Kaoping River basin, (2) sewer system construction to achieve 30% of connection in the basin within 10 years, (3) removal of 10 riverbank landfills, and (4) enforcement of the industrial wastewater discharge standards. After the implementation of the proposed measures, the water quality should be significantly improved and the BOD and nutrient loadings can be reduced to below the calculated carrying capacities.

Assessment of endocrine disruptors: approaches, issues, and uncertainties

This paper focuses on the quantitative risk assessment of environmental endocrine-disrupting chemicals (EDCs) to human health. An EDC can be defined as an exogenous agent that interferes with the normal endocrine signaling and communication mechanisms. The normal feedback control system of natural hormones is responsible for regulatory mechanisms that maintain homeostasis. Hormones deliver their message to target cells by interacting with receptors, initiating signal transduction, gene transcription, and mRNA translation, and ultimately leading to cellular response. Because effects of EDCs include diverse disease endpoints such as cancer, reproductive toxicity, developmental toxicity, immune system effects, acute toxicity, and neurotoxicity, risk assessment of EDCs is necessarily endpoint-specific. From the quantitative viewpoint, it is best to model the normal endocrinology and then extend the model to include impacts attributable to a particular exogenous agent. A practical approach to such a complex process is to break the spectrum of biochemical and biological events into modular components: e.g., pharmacokinetics, biochemical/molecular (including cellular signaling), and cellular response/dynamics. A flexible mathematical procedure that is capable of modeling each of these components is suggested. However, a real biologically based model is not yet feasible because of a lack of necessary biological information. A challenge to risk assessors is how to develop a hybrid risk assessment approach that can use the limited biological information available for a specific agent and avoid relying on a default approach that incorporates no biological information. The USEPA's default approach is to derive benchmark dose (BMD) or benchmark concentration (BMC) on the basis of a predetermined empirical dose-response model. BMD (or BMC) is the highest dose (or concentration and duration) of exposure that is considered unlikely to cause adverse effects in a human population, including sensitive subgroups. Data from two studies are used to stimulate discussion of issues and the needs for new quantitative approaches and data for assessing endocrine disruptors. Statistical concepts about threshold effect and the U-shaped dose-response relationship are also discussed. This report is a condensed version of the one to be published in the monograph of the NATO Advanced Research Workshop, Endocrine Disrupters and Carcinogenesis Risk Assessment" held May 8-12, 2001, in Bialystok, Poland.

Expression of DAZL protein in the human corpus luteum

The DAZL gene and its homologues are required for the development of male and female germ cells in different species. However, their role in other aspects of human reproduction is not known. We have generated a polyclonal antibody to the DAZL protein and developed a sensitive standard curve quantitative-competitive-RT-PCR assay to characterize the expression of DAZL in the human corpus luteum (CL). DAZL transcripts are expressed in the CL, but the concentrations decreased with advancing luteal phase. In accordance with the mRNA data, DAZL protein was most abundant in the early phase CL. Immunohistochemical staining showed DAZL protein in the cytoplasm of granulosa-luteal cells. The distinct expression pattern of DAZL protein in the human CL may play an important role in the regulation of luteal function.

Complete genome sequence of the model actinomycete Streptomyces coelicolor A3(2)

Streptomyces coelicolor is a representative of the group of soil-dwelling, filamentous bacteria responsible for producing most natural antibiotics used in human and veterinary medicine. Here we report the 8,667,507 base pair linear chromosome of this organism, containing the largest number of genes so far discovered in a bacterium. The 7,825 predicted genes include more than 20 clusters coding for known or predicted secondary metabolites. The genome contains an unprecedented proportion of regulatory genes, predominantly those likely to be involved in responses to external stimuli and stresses, and many duplicated gene sets that may represent 'tissue-specific' isoforms operating in different phases of colonial development, a unique situation for a bacterium. An ancient synteny was revealed between the central 'core' of the chromosome and the whole chromosome of pathogens Mycobacterium tuberculosis and Corynebacterium diphtheriae. The genome sequence will greatly increase our understanding of microbial life in the soil as well as aiding the generation of new drug candidates by genetic engineering.

Preparing a human membrane and secreted protein-enriched cDNA library using PCR primers derived from a genomic database

We describe here a strategy for preparing a human membrane and secreted protein (MSP)-enriched cDNA library based on human MSP- and non-MSP-encoding cDNA sequences in the databases. The signal peptide parts of the MSP-encoding cDNA sequences, which currently comprise about half of the estimated total number in humans, were analyzed for common patterns. These patterns form a 'minimal' set of polymerase chain reaction primer candidates of length varying from 9 to 21 nt. The products stemming from each primer candidate were determined and the results allowed us to obtain an 'optimal' mixed-length primer set. Ninety-six percent of the primers in this set were predicted to yield </=10% undesired products, and the desired MSP-cDNA products could be easily separated by gel electrophoresis. The present analysis establishes a methodology for preparing a cDNA library that enables the analysis of individual MSPs. This methodology may also help identify new MSPs. As many cell regulatory processes are mediated by secreted proteins and their membrane-bound receptors, the preparation of a MSP-enriched cDNA library should benefit research on MSPs.

Prior-knowledge-based feedforward network simulation of true boiling point curve of crude oil

Theoretical results and practical experience indicate that feedforward networks can approximate a wide class of functional relationships very well. This property is exploited in modeling chemical processes. Given finite and noisy training data, it is important to encode the prior knowledge in neural networks to improve the fit precision and the prediction ability of the model. In this paper, as to the three-layer feedforward networks and the monotonic constraint, the unconstrained method, Joerding's penalty function method, the interpolation method, and the constrained optimization method are analyzed first. Then two novel methods, the exponential weight method and the adaptive method, are proposed. These methods are applied in simulating the true boiling point curve of a crude oil with the condition of increasing monotonicity. The simulation experimental results show that the network models trained by the novel methods are good at approximating the actual process. Finally, all these methods are discussed and compared with each other.

Expression patterns and transcript concentrations of the autosomal DAZL gene in testes of azoospermic men

The DAZ (Deleted in AZoospermia) gene cluster on the Y chromosome is a strong candidate for the azoospermia factor. The DAZ gene was derived from an autosomal homologue, DAZL (DAZ-Like). This study was designed to assess the functional role of DAZL in human spermatogenesis. The expression patterns and mRNA transcript levels of DAZL in the testes of 17 azoospermic men were therefore examined by immunohistochemical staining and quantitative competitive reverse transcription-polymerase chain reaction. DAZL protein was expressed in the cytoplasm of primary spermatocytes and weakly in spermatogonia. It was detected in the testicular tissues of all subjects with germ cells present. The copy number of the DAZL transcript in normal spermatogenesis (n = 4), hypospermatogenesis or maturation arrest (n = 6), and Sertoli cell-only syndrome (n = 7) ranged from 1.22 x 10(6) to 1.63 x 10(6) per ng of RNA, 1.19 x 10(5) to 2.82 x 10(5) per ng of RNA and 2.83 x 10(4) to 1.23 x 10(5) per ng of RNA respectively. DAZL transcripts were lower in men with spermatogenic failure, and a significant difference was found between the three groups (P < 0.0001). This study suggests that DAZL may play an important role in the human spermatogenic processes of both mitosis and meiosis.

The relationship between maternal self-esteem and maternal attachment in mothers of hospitalized premature infants

The purpose of this study was to examine the relationship between maternal self-esteem and maternal attachment in mothers of hospitalized premature infants. The research instruments administered included: a demographic sheet, the Maternal Self-Report Inventory (MSRI), Rosenberg Self-Esteem Scale, and Leifer's How I Feel About My Baby Now Scale. Thirty-two mothers whose premature infants were medically stable and hospitalized in the NICU were studied. Two hypotheses on the positive relationships between maternal self-esteem and maternal attachment, and global self-esteem and maternal attachment could not be tested by correlational analyses due to the inadequate internal consistency of the How I Feel About My Baby Now Scale. A significant correlation was found between maternal self-esteem and global self-esteem. Thus, maternal role influenced general self-concept in mothers. In addition, it was found that there were no significant correlations between the MSRI and demographic variables, such as: maternal age, marital status, income, and educational level. Another result indicated that increased global self-esteem was correlated (p < .05) with maternal age, income, and educational level. The results of this study provide clinical nurses to pay attention not only to caregiving skills but also to the mother's appraisal of herself as a mother and attachment behaviors.

Capture envelopes of rectangular hoods in cross drafts

The suction fields of the rectangular hoods of various aspect ratios varying from 0.1 to 10 that are subject to the influence of cross drafts were experimentally studied in an apparatus consisting of a hood model/wind tunnel assembly. The velocity field on the symmetry plane was measured with a two-component laser Doppler anemometer. Being under the influence of cross draft, the suction field presents a characteristic capture envelope, which is described by a dividing streamline. The characteristics of the capture envelope were found to be determined by the cross-draft to hood-suction velocity ratio R and the hood-opening aspect ratio AR. The flow characteristics of the hoods with aspect ratios less than unity were dramatically different from those with aspect ratios greater than one. If areas of the hood openings had the same values, the hydraulic-diameter normalized characteristic length scales of the capture zone of the square hood were as same as those of the circular hood. When the diameter of a circular hood was equal to the width of a square hood, the physical dimensions of the capture zones created by these two hoods coincided with each other.

Hemorrhagic viral keratoconjunctivitis in Taiwan caused by adenovirus types 19 and 37: applicability of polymerase chain reaction-restriction fragment length polymorphism in detecting adenovirus genotypes

PURPOSE

Acute keratoconjunctivitis with prominent subconjunctival hemorrhage (SCH) is usually perceived by a clinician as acute hemorrhagic conjunctivitis (AHC) associated with enteroviruses; however, SCH can also be an adenoviruses infection. A rapid and sensitive laboratory diagnosis is helpful for differential diagnosis. Therefore, the sensitivity and applicability of polymerase chain reaction (PCR) and reverse transcription (RT)-PCR diagnoses were evaluated for keratoconjunctivitis associated with viral infection.

METHODS

Conjunctival swabs from patients with acute conjunctivitis were tested using a PCR-restriction fragment length polymorphism (PCR-RFLP) for adenovirus detection and RT-PCR for enterovirus detection. The results were compared with those using the culture isolation and neutralization test; also, the clinical findings of the patients were analyzed with special attention to SCH patterns.

RESULTS

Neither coxsackievirus A type 24 variant (CA24v) nor enterovirus type 70 (EV70) was detected in 113 patients with acute conjunctivitis. The positive results of adenovirus (Ad) were 39.9% by the PCR method and 37.1% by culture isolation. For the patients with adenoviral conjunctivitis, 68.1% was owing to Ad37 and 19.2% was owing to Ad19. SCH was present in 51.5% of the positive cases, and 44.7% of the Ad-positive patients had secondary illnesses.

CONCLUSIONS

SCH can be a predominant presentation of Ad19 and Ad37 keratoconjunctivitis and may herald a new stage in the evolution of adenoviruses. PCR and PCR-RFLP are rapid and reliable methods for Ad detection and typing; however, if the amplified genes and restriction enzymes are not properly selected, they may not be able to detect new genotypes of adenoviruses or the evolution of these viruses.

Characterization of the biologic activities of a recombinant human zona pellucida protein 3 expressed in human ovarian teratocarcinoma (PA-1) cells

OBJECTIVE

This study was undertaken to clone and express a recombinant human zona pellucida protein 3 and to characterize its biologic activities as a sperm ligand and an inducer of the acrosome reaction.

STUDY DESIGN

Human ovarian teratocarcinoma (PA-1) cells were transfected with an expression vector containing human zona pellucida protein 3 complementary deoxyribonucleic acid with a sequence coding for a 6-histidine tail introduced into its 3' end. Purification of the secreted glycoprotein was performed by sequential affinity (lectin and nickel--nitrilotriacetic acid) and ion-exchange chromatography.

RESULTS

Western blot analysis confirmed a molecular weight of approximately 65 kd for the purified product. A cell-free translation system revealed a correctly sized protein backbone of 47 kd. The recombinant human zona pellucida protein 3 demonstrated specific, potent, and dose-dependent competitive inhibition of sperm-zona pellucida binding in vitro under hemizona assay conditions. Recombinant human zona pellucida protein 3 also stimulated the acrosome reaction of live sperm. This effect was fast, dose dependent, and capacitation time dependent. Furthermore, advance incubation with pertussis toxin, an inactivator of heterotrimeric G proteins, blocked recombinant human zona pellucida protein 3--induced acrosomal exocytosis.

CONCLUSION

The recombinant human zona pellucida protein 3 expressed in PA-1 cells manifested the full spectrum of expected biologic activities. It therefore represents a valuable tool for examination of human fertilization and the design of new strategies in diagnosis of male factor infertility and in contraception.

The capture envelope of a flanged circular hood in cross drafts

The flow patterns of an exterior circular hood subject to the influence of various uniform cross drafts were experimentally studied in an apparatus consisting of hood-model/wind-tunnel assembly. A two-component laser Doppler anemometer was employed to measure the velocity field on the symmetry plane. The streamline patterns were obtained from the measured velocity data. The cross draft caused a characteristic envelope similar to a half Rankine body-of-revolution to form in the flow field. The boundary of the envelope is described by a dividing streamline. All streamlines within the envelope lead to the opening; those outside the envelope evolve to the downstream area. The normalized geometry of the capture envelope is theoretically justified and correlated by modifying the potential theory of point-sink-plus-rectilinear-flow. The domain and shape of the envelope enclosing the hood opening are determined primarily by the velocity ratio between the cross draft and hood suction. The correlated formula is applicable to design the hood parameters, including the sizes of opening and flange as well as the location of contaminant sources.

Two-dimensional phase unwrapping with use of statistical models for cost functions in nonlinear optimization

Interferometric radar techniques often necessitate two-dimensional (2-D) phase unwrapping, defined here as the estimation of unambiguous phase data from a 2-D array known only modulo 2pi rad. We develop a maximum a posteriori probability (MAP) estimation approach for this problem, and we derive an algorithm that approximately maximizes the conditional probability of its phase-unwrapped solution given observable quantities such as wrapped phase, image intensity, and interferogram coherence. Examining topographic and differential interferometry separately, we derive simple, working models for the joint statistics of the estimated and the observed signals. We use generalized, nonlinear cost functions to reflect these probability relationships, and we employ nonlinear network-flow techniques to approximate MAP solutions. We apply our algorithm both to a topographic interferogram exhibiting rough terrain and layover and to a differential interferogram measuring the deformation from a large earthquake. The MAP solutions are complete and are more accurate than those of other tested algorithms.

Adult Wilms' tumor associated with polycythemia--a case report

Both Wilms' tumor (nephroblastoma) in adults and polycythemia in Wilms' tumor are rare. Herein we report an extremely rare case of adult Wilms' tumor associated with polycythemia. A 41-year-old female was incidentally found to have right renal mass by abdominal sonography in a routine health examination. Laboratory examination revealed polycythemia (hemoglobin 20.2 g/dL). Although physical examination was unremarkable, CT scan revealed an homogeneous mass at the middle pole of right kidney, and chest x-ray revealed no metastatic lesions. Right radical nephrectomy was performed smoothly. Grossly, the tumor of 5 x 4.5 x 4.5 cm in size was well circumscribed, and had no vascular structure or collecting system involvement. Microscopic features were consistent with adult nephroblastoma. The post-operative course was uneventful. At follow-up, the patient was well, showed no evidence of recurrence and her hemoglobin level had returned to normal (hemoglobin 14.5 g/dl). We suggest that the relationship between polycythemia and Wilms' tumor should be carefully evaluated before surgical treatment.

Oligomerization of ETO is obligatory for corepressor interaction

Nearly 40% of cases of acute myelogenous leukemia (AML) of the M2 subtype are due to a chromosomal translocation that combines a sequence-specific DNA binding protein, AML1, with a potent transcriptional repressor, ETO. ETO interacts with nuclear receptor corepressors SMRT and N-CoR, which recruit histone deacetylase to the AML1-ETO oncoprotein. SMRT-N-CoR interaction requires each of two zinc fingers contained in C-terminal Nervy homology region 4 (NHR4) of ETO. However, here we show that polypeptides containing NHR4 are insufficient for interaction with SMRT. NHR2 is also required for SMRT interaction and repression by ETO, as well as for inhibition of hematopoietic differentiation by AML1-ETO. NHR2 mediates oligomerization of ETO as well as AML1-ETO. Fusion of NHR4 polypeptide to a heterologous dimerization domain allows strong interaction with SMRT in vitro. These data support a model in which NHR2 and NHR4 have complementary functions in repression by ETO. NHR2 functions as an oligomerization domain bringing together NHR4 polypeptides that together form the surface required for high-affinity interaction with corepressors. As nuclear receptors also interact with corepressors as dimers, oligomerization may be a common mechanism regulating corepressor interactions.

Disulfide bond effects on protein stability: designed variants of Cucurbita maxima trypsin inhibitor-V

Attempts to increase protein stability by insertion of novel disulfide bonds have not always been successful. According to the two current models, cross-links enhance stability mainly through denatured state effects. We have investigated the effects of removal and addition of disulfide cross-links, protein flexibility in the vicinity of a cross-link, and disulfide loop size on the stability of Cucurbita maxima trypsin inhibitor-V (CMTI-V; 7 kD) by differential scanning calorimetry. CMTI-V offers the advantage of a large, flexible, and solvent-exposed loop not involved in extensive intra-molecular interactions. We have uncovered a negative correlation between retention time in hydrophobic column chromatography, a measure of protein hydrophobicity, and melting temperature (T(m)), an indicator of native state stabilization, for CMTI-V and its variants. In conjunction with the complete set of thermodynamic parameters of denaturation, this has led to the following deductions: (1) In the less stable, disulfide-removed C3S/C48S (Delta Delta G(d)(50 degrees C) = -4 kcal/mole; Delta T(m) = -22 degrees C), the native state is destabilized more than the denatured state; this also applies to the less-stable CMTI-V* (Delta Delta G(d)(50 degrees C) = -3 kcal/mole; Delta T(m) = -11 degrees C), in which the disulfide-containing loop is opened by specific hydrolysis of the Lys(44)-Asp(45) peptide bond; (2) In the less stable, disulfide-inserted E38C/W54C (Delta Delta G(d)(50 degrees C) = -1 kcal/mole; Delta T(m) = +2 degrees C), the denatured state is more stabilized than the native state; and (3) In the more stable, disulfide-engineered V42C/R52C (Delta Delta G(d)(50 degrees C) = +1 kcal/mole; Delta T(m) = +17 degrees C), the native state is more stabilized than the denatured state. These results show that a cross-link stabilizes both native and denatured states, and differential stabilization of the two states causes either loss or gain in protein stability. Removal of hydrogen bonds in the same flexible region of CMTI-V resulted in less destabilization despite larger changes in the enthalpy and entropy of denaturation. The effect of a cross-link on the denatured state of CMTI-V was estimated directly by means of a four-state thermodynamic cycle consisting of native and denatured states of CMTI-V and CMTI-V*. Overall, the results show that an enthalpy-entropy compensation accompanies disulfide bond effects and protein stabilization is profoundly modulated by altered hydrophobicity of both native and denatured states, altered flexibility near the cross-link, and residual structure in the denatured state.

Enhanced loop DNA folding induced by thymine-CH3 group contact and perpendicular guanine-thymine interaction

A remarkable stabilizing effect induced by T-CH3 group and perpendicular guanine-thymine interactions in the DNA loop conformation has been demonstrated for the d(TTTG) loop structure using UV melting, high resolution NMR, distance geometry, and molecular dynamics studies. Contrary to the previously published d(TTCG) sequence that exhibits no specific inter-nucleotide interaction, we have found that d(TTTG), which differs only by one nucleotide with the d(TTCG) sequence (C7 --> T7), forms a rather stable and well-defined loop structure. Two characteristic structural features account for the stabilization of an otherwise flexible loop structure; the second loop T (T6) residue folds into the minor groove and engages in perpendicular interaction with the G8-NH2, while the third loop T (T7) residue stacks well upon the closing T5 x G8 wobble base pair and exhibits good contacts with many of the loop T5 and T6 sugar protons, which may form a hydrophobic core in the loop region. The importance of the bulky T7-CH3 was also proved by the UV melting study; while d(TTCG) hairpin exhibits a lower melting point (74.5 degrees C) than d(TTTG) hairpin (80.5 degrees C), d(TT(5-methyl)CG) hairpin resumes the same higher melting point (80 degrees C). Similarly, the fact that the melting temperature (74 degrees C) of d(TTTI) is lower than that of d(TTTG) indicates the critical role played by the G8-NH2 group. Our structural studies of the d(TTTG) loop indicate that DNA and RNA use a different strategy to establish stable tertiary folds. Comparison with several other pyrimidine-rich loop hairpins suggests that different minor-groove folding modes exist for the folding thymidine residue.

Y-chromosome microdeletion and its effect on reproductive decisions in taiwanese patients presenting with nonobstructive azoospermia

OBJECTIVES

To investigate the position, extent, and frequency of Y chromosome microdeletions in Taiwanese patients presenting with nonobstructive azoospermia, and to investigate the effect of microdeletions on reproductive decisions.

METHODS

We studied 176 consecutive men with azoospermia in our urology clinic. Polymerase chain reaction tests were performed in 94 patients with nonobstructive azoospermia, and a series of 27 sequence-tagged sites (STSs) mapped within intervals 5 and 6 of Yq11 was selected for analysis. Clinical genetics counseling was provided to couples with microdeletions, and these couples made their own choices about further treatment modalities.

RESULTS

Among 94 patients screened for microdeletion, 11 (11.7%) showed microdeletions of one or more STSs. One had a deletion confined to the azoospermia factor b (AZFb) region (encompassing the RBM gene). Two were found to have deletions of both the AZFb and AZFc regions. Eight patients had deletions in the AZFc region (encompassing the DAZ gene). Five had deletions distal to the DAZ gene family. One had multiple, noncontiguous deletions. In 8 patients with testicular histology available, a lack of genotype/phenotype correlation was noted. Of the 11 couples with deletions, 3 thought microdeletion was a serious defect and opted for an artificial insemination of donor or adoption, 5 chose intracytoplasmic sperm injection, and the other 3 decided to undergo treatment with Chinese medicinal herbs.

CONCLUSIONS

The most commonly deleted region in the Taiwanese population is AZFc. The genes implicated in Taiwanese spermatogenesis defects are the DAZ and RBM gene families. Twenty-seven percent of couples with microdeletions deferred assisted reproductive technologies because of concern about their underlying genetic defects.

Empirical Bayes approach to estimating the number of HIV-infected individuals in hidden and elusive populations

In this paper we estimate the numbers of intravenous drug users (IVDUs) and commercial sex workers (CSWs) in Thailand infected with human immunodeficiency virus (HIV) who have not developed acquired immunodeficiency syndrome (AIDS) directly from the semi-annual HIV serosurveillance data of Thailand from June 1993 to June 1995. We propose a 'generalized removal model for open populations' for estimating HIV-infected population size within a hidden, elusive, and perhaps high-risk population group, for all sampling time when capture probabilities vary with time. We apply empirical Bayes methodology to the generalized removal model for open populations by using the Gibbs sampler, a Markov chain Monte Carlo method. No assumption on the size of the hidden population in question is needed to implement this procedure. The statistical method proposed here requires very little computing and only a minimum of two sets of serosurvey data to obtain an estimate, thereby providing a simple and viable option in epidemiological studies when either powerful computing facilities or abundant sampling data are lacking.

Mechanism of adenosine-induced vasodilation in rat diaphragm microcirculation

The mechanism of adenosine-induced vasodilation in rat diaphragm microcirculation was investigated using laser Doppler flowmetry. Adenosine (10(-5), 3.2 x 10(-5), and 10(-4) M), the nonselective adenosine agonist 5'-N-ethylcarboxamido-adenosine (NECA) (10(-8)-10(-7) M), the specific A(2A) agonist 2-p-(2-carboxyethyl)phenyl-amino-5'-N-ethyl carboxamidoadenosine (CGS-21680) (10(-8)-10(-7) M), and the adenosine agonist with higher A(1)-receptor affinity, R-N(6)-phenylisopropyladenosine (R-PIA) (10(-7), 3.2 x 10(-7), and 10(-6) M) elicited a similar degree of incremental increase of microcirculatory flow in a dose-dependent manner. The ATP-dependent potassium (K(ATP)) channel blocker glibenclamide (3.2 x 10(-6) M) significantly attenuated the vasodilation effects of these agonists. Adenosine-induced vasodilation could be significantly attenuated by the nonselective adenosine antagonist 8-(p-sulfophenyl)-theophylline (3 x 10(-5) M) or the selective A(2A) antagonist 4-(2-[7-amino-2-(2-furyl)[1,2, 4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl) phenol (ZM-241385, 10(-6) M), but not by the selective A(1) antagonist 8-cyclopentyl-1, 3-dipropylxanthine (5 x 10(-8) M). Adenylate cyclase inhibitor N-(cis-2-phenyl-cyclopentyl) azacyclotridecan-2-imine-hydrochloride (MDL-12330A, 10(-5)M) effectively suppressed the vasodilator response of adenosine and forskolin. These results suggest that adenosine-induced vasodilation in rat diaphragm microcirculation is mediated through the stimulation of A(2A) receptors, which are coupled to adenylate cyclase activation and opening of the K(ATP) channel.

Vestibular neuritis: three-dimensional videonystagmography and vestibular evoked myogenic potential results

Eight patients diagnosed with vestibular neuritis received the newly developed three-dimensional videonystagmography (3D VNG) and vestibular evoked myogenic potential (VEMP) examination in order to localize the lesion site. Two (25%) of the 8 patients exhibited spontaneous nystagmus with 3 components, indicating that both the horizontal semicircular canal (HSCC) and anterior semicircular canal (ASCC) were affected. The remaining 6 patients (75%) displayed only horizontal nystagmus, meaning that only the HSCC was involved. Seven (88%) of the 8 patients had bilateral normal VEMPs, revealing sparing of the posterior semicircular canal (PSCC). In a comparative study, another seven patients with vestibular neuritis 1 year post-treatment also received the caloric test, 3D VNG and VEMP examination. Only one patient exhibited spontaneous nystagmus. An absent caloric response of the lesioned side persisted in 5 (71%) of the 7 patients. However, all patients showed normal VEMPs bilaterally. 3D VNG and VEMP examination indicates that vestibular neuritis mainly affects the superior division of the vestibular nerve, which innervates the HSCC and ASCC. Meanwhile, the function of the PSCC and saccule, innervated by the inferior vestibular nerve, is preserved.

Biologically based dose-response model for liver tumors induced by trichloroethylene

The existing extensive laboratory data on trichloroethylene (TCE) and its two metabolites, dichloroacetic (DCA) and trichloroacetic (TCA), are used to explore the relationship among these three compounds. Under the hypothesis that these compounds induce liver tumors in mice through promotion of preexisting initiated cells, it is demonstrated that DCA alone could be responsible for all the response of carcinomas in liver of B6CF(1) mice. The focus of this paper is on how a plausible biological assumption could impact on low-dose risk estimates, rather than on the risk estimate per se. The findings suggest that low-dose risk estimates to humans would be overestimated unless the different background rates between mice and humans are properly accounted for.

Dynamic expression of lunatic fringe during feather morphogenesis: a switch from medial-lateral to anterior-posterior asymmetry

Expression of Lunatic fringe mRNA was studied during feather morphogenesis and showed three stages of dynamic expression pattern. (1) Lunatic fringe was first expressed in the epithelium as a ring bordering the feather primordium when it was initially induced. (2) Shortly after, it showed a polarized pattern, first toward the lateral side of the feather primordium and then made a 90 degrees C switch toward the posterior side of the short bud. It then becomes weakly expressed in the long bud stage. (3) Finally, it is expressed in the marginal plate epithelia of feather filaments. In contrast, Radical fringe is weakly expressed in the feather bud, but is also present in the marginal plate epithelia of feather filaments.