Requirements for kissing-loop-mediated dimerization of human immunodeficiency virus RNA

Sequences from the 5' end of type 1 human immunodeficiency virus RNA dimerize spontaneously in vitro in a reaction thought to mimic the initial step of genomic dimerization in vivo. Dimer initiation has been proposed to occur through a "kissing-loop" interaction involving a specific RNA stem-loop element designated SL1: the RNA strands first interact by base pairing through a six-base GC-rich palindrome in the loop of SL1, whose stems then isomerize to form a longer interstrand duplex. We now report a mutational analysis aimed at defining the features of SL1 RNA sequence and secondary structure required for in vitro dimer formation. Our results confirm that mutations which destroy complementarity in the SL1 loop abolish homodimer formation, but that certain complementary loop mutants can heterodimerize. However, complementarity was not sufficient to ensure dimerization, even between GC-rich loops, implying that specific loop sequences may be needed to maintain a conformation that is competent for initial dimer contact; the central GC pair of the loop palindrome appeared critical in this regard, as did two or three A residues which normally flank the palindrome. Neither the four-base bulge normally found in the SL1 stem nor the specific sequence of the stem itself was essential for the interaction; however, the stem structure was required, because interstrand complementarity alone did not support dimer formation. Electron microscopic analysis indicated that the RNA dimers formed in vitro morphologically resembled those isolated previously from retroviral particles. These results fully support the kissing-loop model and may provide a framework for systematically manipulating genomic dimerization in type 1 human immunodeficiency virus virions.

Purification and characterization of proteasomes from Trypanosoma brucei

Proteasomes are multisubunit proteases that exist universally among eukaryotes. They have multiple proteolytic activities, and are believed to have important roles in regulating cell cycle, selective intracellular proteolysis, and antigen presentation. To determine the possible role that proteasomes may play in controlling the life cycle of African trypanosomes, we have isolated proteasomes from the bloodstream and the insect (procyclic) forms of Trypanosoma brucei by DEAE-cellulose chromatography and glycerol gradient fractionation in the presence of ATP. No 26 S proteasome homologs was identified in T. brucei under these experimental conditions. The proteasomes isolated from these two forms of T. brucei are very similar to the rat blood cell 20 S proteasome in their general appearance under the electron microscope. The profile of trypanosome proteasome subunits in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) has eight visible protein bands with molecular weights ranging from 23 to 34 kDa, and cross-reacted very poorly with the anti-human 20 S proteasome antibodies on immunoblots. Two-dimensional gel electrophoresis of the parasite proteasomes shows a similar number of major subunits with pI's ranging from 4.5 to 7. Using a variety of fluorogenic peptides as substrates, the trypanosome proteasomes exhibited unusually high trypsin-like, but somewhat lower chymotrypsin-like activities, as compared to the rat 20 S proteasome. These proteolytic activities were, however, insensitive to phenylmethylsulfonyl fluoride (PMSF), tosyl-phenylalanine chloromethylketone (TPCK), tosyl-lysine chloromethylketone (TLCK) and trans-epoxy succinyl-L-leucylamido-(4 guanidino) butane (E-64), but the trypsin-like activity of trypanosome proteasomes was inhibited by leupeptin, an aldehyde known to inhibit the trypsin-like activity of mammalian proteasomes, thus ruling out possible contamination by other serine or cysteine proteases. Some quantitative differences in the substrate specificities between the proteasomes from bloodstream and procyclic forms were indicated, which may play a role in determining the differential protein turnovers at two different stages of development of T. brucei.

Inducible nitric oxide synthase gene expression in the brain during systemic inflammation

Inducible nitric oxide synthase (iNOS) is a transcriptionally regulated enzyme that synthesizes nitric oxide from L-arginine that has a key role in the pathophysiology of systemic inflammation and sepsis. Transgenic animals with a null mutation for the iNOS gene are resistant to hypotension and death caused by Escherichia coli lipopolysaccharide (LPS). The regulation of peripheral iNOS has been well studied in sepsis, but little is known about iNOS regulation in the brain during systemic inflammation or sepsis. We know that at baseline there is no detectable iNOS gene expression in the brain, but a detailed neuroanatomical study reveals that early in the course of systemic inflammation there is a profound induction of iNOS messenger RNA in vascular, glial and neuronal structures of the rat brain, accompanied by the production of nitric oxide (NO) metabolites in brain parenchyma and cerebrospinal fluid (CSF). We propose that the spillover of nitrite into the CSF has the potential to be a diagnostic marker for systemic inflammation and sepsis. Pharmacological interventions aimed at regulating iNOS function in the brain might represent a new treatment strategy in sepsis. Brain iNOS may be relevant to the pathophysiology, diagnosis and treatment of systemic inflammation and sepsis.

A purified Drosophila septin complex forms filaments and exhibits GTPase activity

Septin proteins are necessary for cytokinesis in budding yeast and Drosophila and are thought to be the subunits of the yeast neck filaments. To test whether septins actually form filaments, an immunoaffinity approach was used to isolate a septin complex from Drosophila embryos. The purified complex is comprised of the three previously identified septin polypeptides Pnut, Sep2, and Sep1. Hydrodynamic and sequence data suggest that the complex is composed of a heterotrimer of homodimers. The complex copurifies with one molecule of bound guanine nucleotide per septin polypeptide. It binds and hydrolyzes exogenously added GTP. These observations together with conserved sequence motifs identify the septins as members of the GTPase superfamily. We discuss a model of filament structure and speculate as to how the filaments are organized within cells.

Rat LCR1: cloning and cellular distribution of a putative chemokine receptor in brain

We report here the isolation and localization of RLCR1, a rat G-protein-coupled receptor, which is the homologue (94% amino acid identity) of the bovine receptor (LCR1) isolated from a locus coeruleus cDNA library. The deduced amino acid sequence of the RLCR1 encodes a protein of 347 amino acids and yields a hydropathicity profile characteristic of receptors with seven putative transmembrane regions. The structure of the receptor protein encoded by RLCR1 is most similar to that of the Burkitt's lymphoma receptor 2 (43% identical) and C-C chemokine receptor type 1 (38%). The mRNA corresponding to the cDNA was detected in various rat tissues including spleen, liver, heart, and brain. In situ hybridization analysis shows that RLCR1 is distributed both in neurons and glia in the adult rat brain. Levels of RLCR1 mRNA are highest in the ependymal layer as previously reported. In addition, we found that RLCR1 is also expressed at lower levels in cerebral cortex, hippocampus, cerebellum, and brainstem. The finding that LCR1 is expressed in the adult indicates that this receptor influences neuronal function at times after maturation of the brain.

The hypothalamic-pituitary-adrenal axis in anorexia nervosa

Studies examining the function of the hypothalamic-pituitary-adrenal (HPA) axis in anorexia nervosa are reviewed. A principal finding is that of hypercortisolism, associated with increased central corticotropin-releasing hormone levels and normal circulating levels of adrenocorticotropic hormone. Similarities between neuroendocrine findings in anorexia nervosa and in affective disorder are reviewed. The contribution of circadian rhythm disturbances and malnutrition to observed HPA axis abnormalities in anorexia nervosa is also considered. Directions for future research are discussed.

Naturin: a potent bio-immunomodifier in experimental studies and clinical trials

A number of traditional Chinese medicinal herbs have become extremely interesting in the search for potential BRMs in the international medical community, especially in the United States and Japan. Naturin, a new Chinese medical herb produced by XingYa Pharmaceutical Co., Ltd., has enhanced immune response, inhibited tumor metastases and retroviral infection in animal models as well as in clinical studies. The results demonstrated that the inhibition of Natural Killer (NK) and Lymphokine-activated Killer (LAK) cell activity and lymphocyte proliferation was compromised by tumor metastases and retrovirus infection (Murine AIDS), even immunosuppression induced by surgical amputation can be restored by Naturin. It is also shown that Naturin can protect the mice from lethal total body irradiation. These studies indicated that Naturin possesses immunomodulatory effects in vivo for a broad range of stresses. The results of the clinical studies on Naturin have demonstrated: (a) significantly improved symptoms of patients, including MDS, acute and chronic leukemia, aplastic anemia, lung cancer, and association with the increased number and percentage of CD4 (Helper T-cell) which have been reduced in some patients, (b) Lymphocyte proliferation and NK cell activity which were suppressed in cancer patients can be significantly restored by Naturin treatment, (c) the addition of Naturin treatment to patients receiving radiotherapy and chemotherapy augments immune response and reduces radiation and chemotherapy injury, and (d) no cytotoxic side effects were found in patients given Naturin treatment for up to eight months.

Blood cyst of the tricuspid valve

Blood-filled cysts of the heart valves are commonly reported at postmortem examination of infants but are rarely seen in older children and adults. These cysts appear to be benign lesions and should be removed only if they cause problems. We present the case of a patient with a tricuspid valve blood cyst that was surgically removed and then discuss the differential diagnosis and management of these cysts. When a cardiac mass has features suggestive of a blood cyst, radical resection should not be performed unless histologic confirmation of tumor is obtained.

Matrix alters the proliferative response of enterocytes to growth factors

BACKGROUND

Enterocyte growth and differentiation along the crypt-villus axis is a highly controlled process. Crypt cells divide to produce enterocytes that migrate along the villus axis prior to terminal differentiation. Growth factors and basement membrane may be involved in the regulation of this process.

METHODS

IEC-6 proliferation was measured in cells grown on laminin or collagen I by measuring the conversion of Owen's reagent to formazan. Cells were grown with no growth factor, one growth factor (ie, epidermal growth factor, insulin-like growth factor-I, or transforming growth factor-alpha), or a combination of factors.

RESULTS

Enterocyte proliferation was increased in all groups given mitogenic growth factors with additive increases in those given combinations. Enterocytes grown on laminin showed a significantly decreased proliferative response to mitogenic growth factors in all experimental groups. Matrix did not alter seeding efficiency or cell viability.

CONCLUSION

Basement membrane may play a role in the regulation of cell proliferation along the crypt-villus axis.

Corticotropin releasing hormone in the pathophysiology of melancholic and atypical depression and in the mechanism of action of antidepressant drugs

Hypercortisolism in depression seems to preferentially reflect activation of hypothalamic CRH secretion. Although it has been postulated that this hypercortisolism is an epiphenomenon of the pain and stress of major depression, our data showing preferential participation of AVP in the hypercortisolism of chronic inflammatory disease suggest specificity for the pathophysiology of hypercortisolism in depression. Our findings that imipramine causes a down-regulation of the HPA axis in experimental animals and healthy controls support an intrinsic role for CRH in the pathophysiology of melancholia and in the mechanism of action of psychotropic agents. Our data suggest that hypercortisolism is not the only form of HPA dysregulation in major depression. In a series of studies, commencing in patients with Cushing's disease, and extending to hyperimmune fatigue states such as chronic fatigue syndrome and examples of atypical depression such as seasonal affective disorder, we have advanced data suggesting hypofunction of hypothalamic CRH neurons. These data raise the question that the hyperphagia, hypersomnia, and fatigue associated with syndromes of atypical depression could reflect a central deficiency of a potent arousal-producing anorexogenic neuropeptide. In the light of data presented elsewhere in this symposium regarding the role of a hypofunctioning hypothalamic CRH neuron in susceptibility to inflammatory disease, these data also raise the question of a common pathophysiological mechanism in syndromes associated both with inflammatory manifestations and atypical depressive symptoms. This concept of hypofunctioning of hypothalamic CRH neurons in these disorders also raises the question of novel forms of neuropharmacological intervention in both inflammatory diseases and atypical depressive syndromes.

Nucleation of microtubule assembly by a gamma-tubulin-containing ring complex

The highly conserved protein gamma-tubulin is required for microtubule nucleation in vivo. When viewed in the electron microscope, a highly purified gamma-tubulin complex from Xenopus consisting of at least seven different proteins is seen to have an open ring structure. This complex acts as an active microtubule-nucleating unit which can cap the minus ends of microtubules in vitro.

Regulation of clathrin assembly and trimerization defined using recombinant triskelion hubs

Clathrin polymerization into a polyhedral vesicle coat drives receptor sorting at cellular membranes during endocytosis and organelle biogenesis. To study clathrin self-assembly, we expressed the C-terminal third of the clathrin heavy chain in bacteria. The recombinant fragment trimerized, bound clathrin light chains, and morphologically resembled the hub domain of the triskelion-shaped clathrin molecule. Self-assembly of recombinant hubs demonstrated a regulatory role for clathrin light chains and for the distal portions of triskelion legs in clathrin coat formation. Deletion mutagenesis of the hub localized a domain mediating light chain binding and clathrin self-assembly and mapped a transferable trimerization domain. These studies define molecular interactions controlling clathrin self-assembly and establish a recombinant system for future analysis.

The gene encoding for the novel transacting factor proopiomelanocortin corticotropin-releasing hormone responsive element binding protein 1 (PCRH-REB-1) is constitutively expressed in rat pituitary and in discrete brain regions containing CRH or CRH receptors: pathophysiological implications

The nucleotide sequence CTGTGCGCGCAG is a core corticotropin-releasing hormone (CRH) responsive element in the proopiomelanocortin (POMC) promoter that gives 5-7 fold stimulation of POMC transcription by CRH. This region binds a novel transacting factor, proopiomelanocortin corticotropin-releasing hormone responsive element binding protein 1 (PCRH-REB-1), recently cloned from CRH-stimulated pituitary cells. We conducted in situ hybridization histochemistry experiments, using a species-specific, antisense, 35S-labeled PCRH-REB-1 riboprobe, to determine the pattern of PCRH-REB-1 gene expression in the brain, and showed that PCRH-REB-1 mRNA is localized not only in pituitary, but it is also found in discrete brain regions such as septal nuclei, hypothalamus, cortex, hippocampus, amygdala, and cerebellum. Those regions contain CRH or CRH receptors, and respond to CRH. We hypothesize that PCRH-REB-1 may be a marker of cellular responsiveness to CRH in the brain and pituitary, and might therefore be useful in the evaluation of CRH function and in the identification of clinically effective CRH agonists and antagonists.

Focal cerebral ischemia induces CRH mRNA in rat cerebral cortex and amygdala

Corticotropin-releasing hormone (CRH) antagonism has neuroprotective effects in models of ischemia. We examined CRH mRNA by in situ hybridization in a well-established rat model of focal cerebral ischemia caused by permanent middle cerebral artery occlusion (MCAo). In ischemic cortex CRH mRNA levels were elevated 2.6-fold 60 min after MCAo, compared with sham operated animals. CRH mRNA was also induced in the amygdala, 60 min following ischemia, in a pattern which was qualitatively different from that of sham operated animals. This rapid and profound increase in CRH mRNA levels during focal cerebral ischemia is likely to be associated with neurotoxicity, as CRH antagonism has been reported to cause a significant reduction in neuronal loss during ischemia.

Echocardiographic evaluation of partial anomalous pulmonary venous drainage

OBJECTIVES

This study was undertaken to determine the accuracy of routine echocardiography in the detection of partial anomalous pulmonary venous drainage.

BACKGROUND

Although there are occasional case reports of the echocardiographic appearance of partial anomalous pulmonary venous drainage, no large series have addressed the accuracy of this technique in a large cohort of patients.

METHODS

Between January 1983 and December 1993, 50 patients with partial anomalous pulmonary venous drainage (with or without an associated atrial septal defect as the only other significant intracardiac defect) were identified from the data base at the Hospital For Sick Children, Toronto. Routine echocardiographic reports were reviewed, and the results were compared with surgical or catheterization findings. Risk factors related to diagnostic errors were sought using a Fisher exact test, chi-square analysis, t test and Kruskal-Wallis analysis of variance.

RESULTS

Confirmation of the diagnosis was available in 45 patients whose data were subsequently used for risk factor analysis. The median age at echocardiography was 4.1 years (range 1 month to 18 years). Right-sided drainage was present in 43 patients (86%), with left-sided drainage in 7 (14%). Thirteen patients had an intact atrial septum, 7 a patent foramen ovale and 30 a secundum atrial septal defect. Right ventricular dilation was observed in 46 patients. Two had normal dimensions (two not assessed). The diagnosis was missed by echocardiography in 15 (33%) of the 45 patients with a confirmed diagnosis. Year of study and use of color flow mapping were the only significant variables related to detection rate (7% missed diagnosis with vs. 62% without the use of color flow, p < 0.0005). The median year of missed diagnosis was 1985 versus 1990 (p < 0.002). Transesophageal echocardiography accurately defined the site of drainage in all three patients in whom it was utilized.

CONCLUSIONS

Two-dimensional echocardiography in conjunction with color flow mapping is a valuable tool for the diagnosis of partial anomalous pulmonary venous drainage.

A molecular mechanism for stress-induced alterations in susceptibility to disease

Corticotropin-releasing hormone (CRH) is a 41-amino acid peptide which mediates behavioural and physiological responses to stress. A major target of CRH is the proopiomelanocortin (POMC) gene. Three transcription factors have been identified that affect transcription of the POMC gene by binding to two different sites within the CRH-responsive element of that promoter. We searched Genbank and found that nucleotide sequences in the POMC promoter which bind POMC-transcription factors are also contained in the genome of HIV-1 and cytomegalovirus, in c-fes and human MAT-1 breast cancer oncogenes, and in proinflammatory molecules, such as the interleukin-1 beta converting enzyme. We hypothesise a mechanism of hormone action by which a peptide hormone, such as CRH, might affect disease susceptibility by eliciting the production of transcription factors which may bind to unexpected intracellular targets, such as viruses, oncogenes, or the genes encoding for inflammatory mediators. Infection, inflammation, and possibly neoplastic transformation would thus be facilitated. This hypothesis can be tested. If confirmed, CRH antagonists may prove useful in the treatment of disorders whose pathophysiology involves molecules that respond to CRH-regulated POMC transcription factors.

Behavioural interventions in the control of human immunodeficiency virus and other sexually transmitted diseases--a review

In the absence of an effective cure or vaccine, acquired immune deficiency syndrome (AIDS) preventive measures have focused on education and information to prevent and reduce high risk behaviours associated with AIDS/human immunodeficiency virus (HIV) transmission. Strategies to change behaviour can be divided into 4 stages: information dissemination, motivation and persuasion, self-efficacy and skills development, and community support to sustain behavioural change. This paper discusses the application of behaviour change and social learning theories to control the spread of AIDS/HIV and other sexually transmitted diseases. A review of the effectiveness of behavioural interventions among high risk groups such as homosexuals, intravenous drug users, commercial sex workers and adolescents is also outlined. A deeper understanding of and an increased attention to social network, organisational, cultural and environmental factors influencing behaviour is needed for the implementation of behavioural interventions. Behavioural strategies that focus on the individual must be supplemented with efforts to create economic, political and social environments that support the behavioural change.

Localization of interleukin-1 beta converting enzyme mRNA in rat brain vasculature: evidence that the genes encoding the interleukin-1 system are constitutively expressed in brain blood vessels. Pathophysiological implications

Interleukin (IL)-1 beta-converting enzyme (ICE) cleaves the biologically inactive precursor form of IL-1 beta into mature, bioactive IL-1 beta. Because of the potent effects of IL-1 in blood vessels, we conducted an in situ hybridization study to determine whether ICE mRNA is constitutively expressed in adult rat brain vasculature. Using in situ hybridization histochemistry, we were able to demonstrate that mRNA in blood vessels scattered throughout the brain. In a second set experiments, we found that the genes encoding not only ICE, but also IL-1 alpha, IL-1 beta, IL-1 receptor antagonist (IL-1ra), and the IL-1 type I receptor are expressed in brain vasculature. To our knowledge this is the first report documenting the expression of the genes encoding all of the functional elements of the IL-1 system in the same tissue. Our findings have three pathophysiological implications. First, they indicate a possible site where peripheral IL-1 may act in the brain. The vascular IL-1 system stimulates the production of nitric oxide and prostanoids, which could act as mediators of the effects of peripheral IL-1 in the central nervous system. Additionally, vascular IL-1 is known to activate adhesion molecules; our data that the genes encoding the IL-1 system are expressed in brain vasculature further support the concept that IL-1 is implicated in the pathophysiology of atherosclerosis and stroke. Finally, in the context of previous studies documenting that IL-1ra inhibits the effects of IL-1 on endothelial cells, our findings of endogenous IL-1ra mRNA in brain vasculature indicate that IL-1ra might be an endogenous vascular protective agent.

Isolation, characterization and expression of the gene that encodes D-arabinitol dehydrogenase in Candida tropicalis

The gene (ARD) that encodes NAD-dependent D-arabinitol dehydrogenase (ArDH) in the pathogenic fungus Candida tropicalis (Ct) was cloned by transforming Escherichia coli (Ec) BW31M (araCc) with a plasmid library of Ct genomic DNA and selecting for D-arabinitol-utilizing (D-arab+) clones. Plasmid DNA from a D-arab+ clone retransformed fresh Ec BW31M cells to D-arab+; these cells produced both ArDH catalytic activity and a 31-kDa protein recognized by antibodies to native Ct ArDH. The plasmid contained an 846-bp open reading frame (ORF) that encoded a deduced protein of 282 amino acids (aa) (30,748 Da). Four partial aa sequences from Ct ArDH were present in the deduced aa sequence, thus verifying that Ct ARD had been cloned. Ct ArDH was 95% identical to ArDH from Candida albicans (Ca), 85% identical to a xylitol dehydrogenase (XDH) from Pichia stipitis (Ps) and 20-25% identical to many other short-chain dehydrogenases. Ct ArDH, Ca ArDH and Ps XDH were typical short-chain dehydrogenases except that they lacked an N-terminal Gly that is conserved in other members of this family. Thus, these enzymes may represent a subclass of closely-related fungal pentitol dehydrogenases. Large amounts of recombinant ArDH (re-ArDH) were produced in Ec and purified by dye ligand affinity chromatography. The physical and catalytic properties of re-ArDH were similar to those of native Ct ArDH, and re-ArDH and native ArDH performed similarly in an automated enzymatic assay for D-arabinitol in human serum.

Beliefs and attitudes as determinants of cervical cancer screening: a community-based study in Singapore

BACKGROUND

The investigation of cervical cancer screening acceptance in relation to health beliefs and attitudes presents a challenge in a multiethnic population such as Singapore's, where the uptake is currently suboptimal in high-risk groups. This study attempts to identify cognitive barriers to screening activity in order to suggest possible directions for cervical cancer prevention efforts.

METHODS

A cross-sectional survey consisting of a household interview of 640 randomly selected women ages 21-65 years was performed. The screening history and future intention to have a Pap smear were elicited, and attitudes toward cancer and the Pap smear as expressed in 14 statements were measured on a five-point scale.

RESULTS

Of the respondents, 73.1% were aware of the Pap smear, and about half (49.7%) had obtained the information from a doctor or nurse. Overall, the belief in personal susceptibility to cancer was low (58.9%) and a substantial proportion (48.7%) of women were of the attitude that cancer could not be prevented. The effect on a future intention to have a smear varied between women who had had and women who had not had a smear. Among the former, perceived barriers such as discomfort and embarrassment had a significant influence, while a belief in personal susceptibility was an important determinant for the latter group.

CONCLUSIONS

The means of increasing the acceptance of the Pap smear, both for the first time and subsequently, are culture-specific and must address the appropriate health beliefs and attitudes. In Singapore, such efforts should include not only influencing awareness and perceptions through public education but also reducing barriers by creating an appropriate environment for the delivery of this important health service.

Localization of corticotropin-releasing hormone (CRH) receptor mRNA in adult rat brain by in situ hybridization histochemistry

Even though functional CRH receptors have been identified in several brain regions by ligand binding, the identity of brain areas expressing the CRH receptor gene has not been described. The recent cloning of the rat CRH receptor gene has permitted us to conduct an in situ hybridization histochemistry study to localize CRH receptor mRNA in brain, using an antisense 35S-labeled riboprobe and autoradiography. In virus- and pathogen-free, unstressed, adult male Sprague-Dawley rats we observed CRH receptor gene expression in several brain regions, most of which had been previously shown to bind radiolabeled CRH. Those regions include the pituitary, olfactory bulb, hippocampal formation, cerebral and cerebellar cortexes, hypothalamus, median eminence, amygdala, olfactory tubercle, choroid plexus, thalamus, and inferior colliculus. Further studies are needed to determine the cell types expressing both CRH receptor mRNA and the CRH receptor peptide in nervous system as well as in peripheral tissues.

Understanding asthma: patient survey

Eight hundred and two adult patients attending five randomly selected polyclinics in Singapore were interviewed to assess their understanding of asthma. Knowledge of asthma mechanism and its medications was poor with a mean score of 1.4 (median: 1) out of a total score of 6. About a third knew that asthma is due to narrowing of airways and a quarter knew the action of bronchodilators. Only 4.4% (27) knew that steroids decrease airway swelling or inflammation. The best knowledge score was associated with subjects who had the highest education, who had a family history and who had been exposed to pamphlets and books. Incorrect use of prophylaxis was also evident with only one-third (37%) using steroid inhalers regularly as prescribed. Only half (54.5%) of those with no schooling used the correct inhaler technique. Doctors were a source of information for only 49.9% (400) of the patients and it was those with the highest education who were most likely to get information from the doctors. Pamphlets were a source of information for less than one-fifth (16.2%) of the subjects. Greater emphasis should be given to patient education by doctors to help patients understand asthma and its treatment. Important target groups are the older, lesser educated and the moderate or severe patients on steroid inhalers.

A transcribing RNA polymerase molecule survives DNA replication without aborting its growing RNA chain

We have demonstrated elsewhere that a precisely placed, stalled Escherichia coli RNA polymerase ternary transcription complex (polymerase-RNA-DNA) stays on the DNA template after passage of a DNA replication fork. Moreover, the bypassed complex remains competent to resume elongation of its bound RNA chain. But the simplicity of our experimental system left several important questions unresolved: in particular, might the observation be relevant only to the particular ternary complex that we studied, and can the finding be generalized to a transcribing instead of a stalled RNA polymerase? To address these issues, we have created three additional ternary transcription complexes and examined their fates after passage of a replication fork. In addition, we have examined the fate of moving RNA polymerase molecules during DNA replication. The results suggest that our previous finding applies to all transcription intermediates of the E. coli RNA polymerase.

Lifestyle and behavioural risk factors associated with asthma morbidity in adults

We studied the association between morbidity and personal lifestyle/behavioural factors that predispose to exposure to known environmental precipitants of asthma, in a group of asthmatics (n = 787) in primary-care clinics. Clinical severity of asthma was determined by questions regarding the frequency of daytime or nocturnal attacks, the number of visits to primary care or hospital emergency departments for treatment of acute attacks, and the number of hospitalizations, as well as the amount of sick leave in the past year. Questions concerning risk factors included ethnicity, clinical atopic status (current rhinitis/eczema), smoking, occupation, keeping of pets, rugs and carpets, use of brooms, burning of mosquito coils or incense, and outdoor air pollution, as well as the patient's knowledge of asthma care. The most significant independent predictors of asthma morbidity, identified from multivariate logistic regression analyses, were current keeping of either pets or rugs/carpets (OR 1.49; 95% CI 1.12-1.99), and current high-risk occupations (OR 0.59, 95% CI 0.40-0.89). A multiplicity of interacting factors and behavioural responses appear to influence the effects of allergens and other environmental precipitants on asthma morbidity in patients.