Conjugative transposition: Tn916 integrase contains two independent DNA binding domains that recognize different DNA sequences

Transposition of the conjugative transposon Tn916 requires the activity of a protein, called Int, which is related to members of the integrase family of site-specific recombinases. This family includes phage lambda integrase as well as the Cre, FLP and XerC/XerD recombinases. Different proteins, consisting of fragments of Tn916 Int protein fused to the C-terminal end of maltose binding protein (MBP) were purified from Escherichia coli. DNase I protection experiments showed that MBP-INT proteins containing the C-terminal end of Int bound to the ends of the transposon and adjacent plasmid DNA. MBP-INT proteins containing the N-terminal end of Int bound to sequences within the transposon close to each end. Competition binding experiments showed that the sites recognized by the C- and N-terminal regions of Int did not compete with each other for binding to MBP-INT. We suggest that Tn916 and related conjugative transposons are unique among members of the integrase family of site-specific recombination systems because the presence of two DNA binding domains in the Int protein might allow Int to bridge recombining sites, and this bridging seems to be the sole mechanism ensuring that only correctly aligned molecules undergo recombination.

Transcription function of each base pair in the control region of the adenovirus VARNA1 gene

Eighty-seven mutants with single-base substitution in the control region (from -44 to +70) of the adenovirus VARNA1 gene were generated, including nearly every base pair, to examine the role of DNA sequences within this control region for regulating transcription. The effect of these mutations on transcription of the gene was determined in vitro using cytoplasmic S100 extracts from human KB cells. Mutations at -37T, -35A, -29T, -28A, -25C, -18A, -17A, -16A, -13A, -9C, -8C, and -1C in the 5'-flanking region reduced transcription of the gene. Thus two positive regulatory elements, from -44 to -25 and from -18 to +2, interspersed with a putative negative regulatory element were defined. Furthermore, a distinct A-rich purine stretch in the -18 to +2 element was identified. Point mutations in the pyrimidine-rich sequence immediately upstream of the A block promoter element reduced transcription of the gene. Mutations in the GTGG direct repeats of the A block promoter element drastically decreased transcription. Furthermore, mutations that altered the AT-rich sequence immediately downstream of the A block element to become less AT-rich decreased transcription. Mutations of the base pairs at +43C, +45T, and +51A in the inter-block element moderately reduced transcription efficiency of the gene. Mutations at the central four base pairs, GTTC, of the B block palindrome severely affected transcription. These unique sequence motifs and their exact base pairs were proven to be important for regulating transcription of the VARNA1 gene.

[Free medial leg flap with fasciocutaneous branch of tibial nutrient artery]

According to the results of anatomical study in 20 fresh cadaver legs and transparent specimens of 10 medial leg flaps, it is found that the tibial nutrient artery arises from the posterior tibial artery and runs obliquely downwards close to the surface of the popliteal muscle, and at the level of 61.62 +/- 15 mm below the tibial tuberosity it sends out the fasciocutaneous branch, which becomes one of the main nutritional vessels of the medial area of the leg. Vascularized transplantation of the medial leg free flap which is supplied by the fasciocutaneous branch of the above named artery has been undertaken with satisfactory results clinically.

Tyrosinase-based ruthenium dispersed carbon paste biosensor for phenols

Highly sensitive biosensors for phenolic compounds, based on the incorporation of the enzyme tyrosinase within metal-dispersed carbon paste matrices are described. In particular, ruthenium-doped carbon pastes display excellent electrocatalytic activity for the reduction of the enzymatically generated quinone species. Hence, convenient quantitation of micromolar concentrations is feasible at 0.0 V (vs. Ag/AgCl reference), with a greatly enhanced response compared to conventional carbon-paste tyrosinase biosensors. The influence of various experimental variables is explored. Fast, sensitive and reproducible flow injection detection of phenolic compounds is illustrated. Analogous improvements are reported for tyrosinase-rich plant tissue electrodes.

Substance P and substance P receptor histochemistry in human neurodegenerative diseases

Substance P immunoreactivity is localized in discrete subsets of neurons in the human cerebral cortex and basal ganglia. In the normal human cerebral cortex, a subset of aspiny local circuit neurons in deep cortical layers and the cortical subplate contain preprotachykinin mRNA and substance P immunoreactive. These neurons, which contain NADPH diaphorase (NO synthase) activity, are strikingly depleted in Alzheimer's disease--in contrast to other local circuit neurons--suggesting that they may be an early target of the degenerative process. In the human basal ganglia, substance P immunoreactivity and mRNA are localized in a subset of spiny striatal neurons that project to the internal segment of the globus pallidus. These neurons are enriched in D1 dopamine receptors and dynorphin, and are calbindin and DARP 32 immunoreactive. A separate subset of aspiny striatal local circuit neurons also contain substance P immunoreactivity. Fiber and terminal staining is prominent in the matrix compartment of the ventromedial striatum and persists dorsally as a rim outlining patches that contain lesser amounts of immunoreactivity. Intense fiber and terminal staining is found in the pars reticulata of the substantia nigra. In Huntington's disease, substance P is depleted in the striatum in parallel with the dorsoventral gradient of neuronal loss. Terminal staining is progressively depleted in the pallidum and substantia nigra in tandem with striatal atrophy. Substance P receptor immunoreactivity, defined with two polyclonal antisera raised against synthetic peptides derived from the substance P receptor sequence, intensely labels a subset of large neurons in the nucleus basalis and striatum identical to neurons labeled with choline acetyltransferase and nerve growth factor receptor antibodies (although striatal cholinergic neurons do not contain nerve growth factor receptor immunoreactivity in the human). These cholinergic neurons resist degeneration in Huntington's disease but are sensitive to degeneration in Alzheimer's disease. Less intensely labeled neurons include pyramidal neurons in the hippocampal CA2 field, nonpyramidal neurons in CA1-4, pyramidal and nonpyramidal neurons in deep neocortical layers and in the cortical subplate. Substance P receptor immunoreactivity is not well defined in the human globus pallidus or substantia nigra.

Foetal endocrine maturation

In domestic ruminants such as the sheep, birth is effected through sequential maturation of the foetal hypothalamic-pituitary-adrenal (HPA) axis, leading to the increased output of cortisol. Factors regulating foetal pituitary adrenocorticotrophin (ACTH) secretion have been delineated, and these include corticotrophin releasing hormone (CRH), arginine vasopressin, prostaglandin (PG) E2 and endogenous opioids. The pre-partum increase in foetal plasma ACTH is associated with a rise in pro-opiomelanocortin (POMC) mRNA in the foetal pars distalis, and with an altered pattern of POMC post-translational processing. Foetal adrenal activation results from an increase in ACTH receptors and enhanced coupling through the Gs protein to adenylate cyclase, and increased expression of key steroidogenic enzymes including P450c17. Cortisol modulates the mechanism by which ACTH activates foetal adrenal function, through specific glucocorticoid receptors (GR) in the foetal adrenal cortex. Although the numbers of GR change with gestation, the relative abundance of GR mRNA does not, pointing to post-translational regulatory mechanisms. Cortisol also stimulates an increase in the concentration of its own high affinity binding protein (corticosteroid binding globulin; CBG) in the foetal circulation, apparently by increasing CBG gene expression in the foetal liver, and by altering the extent of foetal CBG glycosylation in a manner that would be expected to decrease the metabolic clearance of this glycoprotein. Clear evidence for placental CRH and ACTH production is lacking in sheep, but PGE2, produced in increasing amounts by the placenta during late pregnancy, may augment the drive to HPA maturation. Aspects of the maturational pathway of cortisol biosynthesis have been described in other species, including the horse, and some comparison is made with the more detailed information currently available from species such as the sheep.

A fundus photographic method with narrow spectral band luminance

We perfected the narrow spectral band fundus photographic system using interference filters at the wavelengths of 417, 478, 500, 530, 547, 570, 589, 607, 628 and 648 nm. Tests about the light penetration of filters and exposure of various brand films were made on this system. Studies of the contrast of fundal tissues and structures under the different narrow spectral band light were made on 43 Chinese fellow eyes. The results indicates that the interference filters of 570 nm have the highest light penetration. Kodak and Gongyuan films (make in China) are the optimal ones. Narrow spectral band fundus photography can eliminate the chromatic aberration and therefore improve the documentation of fundal details, enhance the contrast of pictures as compared with routine white light fundus photography.

Insulin-like growth factor-II (IGF-II) messenger ribonucleic acid is expressed in steroidogenic cells of the developing ovine adrenal gland: evidence of an autocrine/paracrine role for IGF-II

Insulin-like growth factors (IGFs) are potent mitogenic and differentiation-promoting factors that regulate the growth and development of many fetal tissues. Their role in the development of the adrenal gland and activation of its function is not known. The latter is crucial in providing the stimulus for the maturation of various fetal organs and determines the onset of parturition in sheep. To examine the hypothesis that IGFs are important autocrine/paracrine regulators of fetal adrenal development in vivo, we localized IGF-I and IGF-II mRNAs and peptides in the adrenal glands of developing sheep fetuses and correlated the cellular distribution with localization of 3 beta-hydroxysteroid dehydrogenase, tyrosine hydroxylase, and phenylethanolamine-N-methyltransferase enzymes by immunohistochemistry. Adrenal glands from 60- to 75-day-old (n = 4), 100- to 110-day-old (n = 4), 120- to 130-day-old (n = 4), and 145- to 147-day-old (term; n = 4) fetal sheep and 1- to 4-day-old newborn lambs (n = 4) were dissected and either snap-frozen or fixed. Total RNAs were subjected to Northern analysis using ovine IGF-I and IGF-II cDNA probes. Seven IGF-II transcripts of 1.2-6.0 kilobases (kb) were identified in the adrenal glands of fetuses at all gestational ages, and in the newborn. By densitometry, the abundance of IGF-II mRNA was highest in the fetal adrenal gland at 60 days, decreased slightly between 60 and 100 days, remained relatively constant until term, and decreased significantly after birth. At all gestational ages, IGF-II mRNA was detectable in significantly greater abundance than IGF-I mRNA. IGF-I and IGF-II mRNAs were localized by in situ hybridization using 35S-labeled anti-sense cRNA probes, and the peptides by immunohistochemistry using specific antisera. Low levels of IGF-I mRNA were detected in the zona fasciculata, but not in the zona glomerulosa. There was strong hybridization of the IGF-II cRNA to the zona glomerulosa and fasciculata and to the capsule. The hybridization signal was greater in the zona fasciculata than in the zona glomerulosa. IGF-II mRNA was also detected in groups of cells within the medulla. Localization of IGF-II mRNA by in situ hybridization correlated well with the distribution of IGF-II immunoreactivity and with 3 beta-hydroxysteroid dehydrogenase-positive cells in the cortex and in groups of cells within the medulla.(ABSTRACT TRUNCATED AT 400 WORDS)

Voltage-sensitive elevation of cytosolic [Ca2+] in guinea-pig cardiac myocytes elicited by calcitonin gene-related peptide

We have studied the effect of the 37-amino acid cardioactive peptide, calcitonin gene-related peptide (CGRP) on cytosolic [Ca2+] in guinea-pig ventricular myocytes following depolarization. Cytosolic [Ca2+] was measured in single myocytes using fura-2. The application of 20 mM K+ led to a transient rise of cytosolic [Ca2+] followed by an exponential decline. The subsequent application of 2 nM CGRP resulted in a marked increase in cytosolic [Ca2+]. In contrast, no such response was obtained without prior depolarization. The results suggest a basis for the cardiotropic effects of CGRP through an influence on cytosolic [Ca2+].

Toward a more culturally sensitive DSM-IV. Psychoreligious and psychospiritual problems

In theory, research, and practice, mental health professionals have tended to ignore or pathologize the religious and spiritual dimensions of life. This represents a type of cultural insensitivity toward individuals who have religious and spiritual experiences in both Western and non-Western cultures. After documenting the "religiosity gap" between clinicians and patients, the authors review the role of theory, inadequate training, and biological primacy in fostering psychiatry's insensitivity. A new Z Code (formerly V Code) diagnostic category is proposed for DSM-IV: psychoreligious or psychospiritual problem. Examples of psychoreligious problems include loss or questioning of a firmly held faith, and conversion to a new faith. Examples of psychospiritual problems include near-death experiences and mystical experiences. Both types of problems are defined, and differential diagnostic issues are discussed. This new diagnostic category would: a) improve diagnostic assessments when religious and spiritual issues are involved; b) reduce iatrogenic harm from misdiagnosis of psychoreligious and psychospiritual problems; c) improve treatment of such problems by stimulating clinical research; and d) encourage clinical training centers to address the religious and spiritual dimensions of human existence.

Relationship between spectral measures of heart rate variability and ventricular ectopic activity in patients with idiopathic ventricular tachycardia

This study examines the relationship of hourly spectral measures of heart rate variability (HRV) to the occurrence of ventricular ectopic (VE) activity in 20 patients with idiopathic ventricular tachycardia and frequent VE's. Spectral measures of HRV were obtained from 24-hour Holter recordings from the patients in a drug free state and included the total energies in the spectrum, the low frequency components (L) (0.04-0.15 Hz) representing predominantly sympathetic tone with some contribution from the parasympathetic and high frequency components (H) (0.15-0.4 Hz) representing mainly parasympathetic tone. A high H component (parasympathetic) was defined as area > 12 msec and high L components (sympathetic) as area > 30 msec. On an hourly analysis of spectral components in relation to VE activity, VE's occurred significantly more frequently during periods of low H and low L (F = 20.5, DF = 3, P < 0.0001). The number of VE's did not differ statistically in the other combinations of H and L components (low H, low L = 612.8 (50.1); high H, low L = 180.1 (36.8); low H, high L = 338.4 (58.9); high H, high L = 204.9 (17.7) VE's/hr (SEM). The results suggest that VE's are more frequent during periods of low H and low L and are diminished when either H or L are increased in patients with idiopathic ventricular tachycardia. The results would be consistent with the hypothesis that the parasympathetic nervous system has an electrophysiologically stabilizing effect on the myocardium.

[Effects of propafenone, quinidine, and their combination on ventricular fibrillation threshold in dogs]

The effects of propafenone (Pro), a new Ic anti-arrhythmic agent (AAA), quinidine (Qui), and their combination on ventricular fibrillation threshold (VFT) and other electrophysiological properties were evaluated in 20 dogs. VFT was determined by a train of pulses, 4 ms in duration, delivered at 10 ms intervals. The results showed that in normal anesthetized, open-chest dogs: (1) Pro decreased VFT by 21.4%; (2) Qui increased VFT by 75.5%; (3) the Pro-induced decreased VFT was abolished by simultaneous administration of Qui; and (4) the above effects of the two drugs used separately or in combination on VFT were not related to their effects on ventricular effective refractory period and atrioventricular conduction time.

Prenatal diagnosis of placenta previa/accreta with color Doppler ultrasound

A case of placenta previa/accreta was diagnosed at 23 weeks' gestation using color Doppler ultrasound. Imaging showed an unusually intense blood flow within the placental sonolucent spaces and the hypervascularization patterns within the placental and the non-placental tissues. Highly pulsatile venous flow patterns were detected within the placental blood lakes and the subplacental venous complex. A strong association between the lacunar flow pattern and the abnormally adherent placentation was confirmed by the color Doppler sonographic findings.

Imaging Surface Atomic Structure by Means of Auger Electrons

Measurements of the complete angular distribution of Auger electrons emitted from well-defined platinum[111] single-crystal surfaces have led to the discovery that the distributions are composed of "silhouettes" of surface atoms "back lit" by emission from atoms deeper in the solid. Theoretical simulations of Auger electron angular distributions based upon atomic point emitters and spherical atomic scatterers of uniform cross section are in close agreement with these experimental results, but opposite to previous theoretical predictions. In view of the definitive results obtained and the straightforward agreement between theory and experiment, angular distribution Auger microscopy (ADAM) is useful for direct imaging of interfacial structure and investigation of electron-solid interactions in the physical and biological sciences and engineering. Applicability of ADAM is illustrated by images obtained for monolayers of silver and iodine on platinum[111].