Bifocal Stabilisation of Acute Acromioclavicular Joint Dislocation using Suture Anchor and Temporary K-Wires: A Retrospective Analysis

Introduction

The acromioclavicular joint (ACJ) is a major link connecting the upper limb to the torso. The acromioclavicular and coracoclavicular (CC) ligaments help in stabilising the joint. We feel it is prudent to address both these ligament injuries, to achieve optimum result. This study was undertaken to analyse the results of a simple frugal surgical technique we used to deal with this injury considering stabilisation for both these ligaments.

Materials and methods

In this retrospective study, skeletally mature patients with Type III, IV or V ACJ dislocations who underwent open reduction and stabilisation of the joint with temporary K-wires, repair of the capsule and augmentation of CC ligaments with suture anchors were included. Clinico-radiological and functional outcome was evaluated. Functional assessment of the upper limb was analysed using the Disabilities of Arm, Shoulder, and Hand Score (DASH), Constant shoulder score (CSS) and Oxford shoulder score (OSS).

Results

Clinical and radiological evaluation of the 32 patients who had completed two years from the index surgery, was done. Out of the 37 patients included initially, five were lost in follow-up. Majority of the subjects included were males and type V was the most common injury. Mean pre-operative CC distance on the affected side was 13.92±4.94mm. In the immediate post-operative radiograph, it was 7.63±2.08mm and in the final follow- up was 9.36±2.75mm. Measurements were taken by two independent investigators and inter, and intra-observer reliability were analysed by Interclass correlation coefficient. Excellent functional outcome was noted despite the 1.81±1.50mm average loss of correction. At final follow-up, mean DASH score was 4.67±4.18, Oxford shoulder score was 44.06±2.44 and Constant shoulder score was 86.37±5.81. The severity of the injury had no significant effect on the functional outcome post our method of stabilisation and rehabilitation.

Conclusion

Bifocal fixation restores the multidirectional stability of the disrupted ACJ. Adequate radiological reduction, good functional outcome and simplicity of execution make this technique an undemanding one for use in regular practice.

Utility of serum Galactomannan in diagnosing COVID-19 patients with suspected IPA: an observational study in resource limited settings

OBJECTIVE

To study the utility of Galactomannan (GM) antigen as a screening marker for diagnosing invasive pulmonary aspergillosis (IPA) in coronavirus disease 2019 (COVID-19) patients.

PATIENTS AND METHODS

The serum samples from patients with severe COVID-19 diseases admitted to the Critical Care Unit were collected on the 5th day of admission for GM screening. The samples were analysed by enzyme linked immune sorbent assay (ELISA) and GM index of more than 1 was considered as positive. All GM positive patients were serially followed until discharge or death.

RESULTS

The GM was raised in serum of 12 out of 38 patients, indicating an incidence of possible COVID-19 associated IPA (CAPA) in 31.57% of patients. The median age of these CAPA patients was 56.5 years, males were significantly more affected than females. The inflammatory marker serum ferritin was raised in all 12 patients (median value of 713.74 ng/ml), while IL-6 was raised in 9 patients (median value of 54.13 ng/ml). None of these patients received antifungals. Their median length of hospital stay was 20 days (IQR: 12, 34 days). All these patients succumbed to the illness.

CONCLUSIONS

The serum GM appears to be sensitive diagnostic tool to identify early IPA in COVID-19 patients and pre-emptive antifungal therapy could play a role in salvaging these patients.

Cardiovascular adverse events are associated with usage of immune checkpoint inhibitors in real-world clinical data across the United States

Background

Immune checkpoint inhibitors (ICIs) can cause life-threatening cardiovascular adverse events (CVAEs) that may not be attributed to therapy. The outcomes of clinical trials may underestimate treatment-related adverse events due to restrictive eligibility, limited sample size, and failure to anticipate selected toxicities. We evaluated the incidence and clinical determinants of CVAEs in real-world population on ICI therapy.

Patients and methods

Among 2 687 301 patients diagnosed with cancer from 2011 to 2018, 16 574 received ICIs for any cancer. Patients in the ICI and non-ICI cohorts were matched in a 1 : 1 ratio according to age, sex, National Cancer Institute comorbidity score, and primary cancer. The non-ICI cohort was stratified into patients who received chemotherapy (N = 2875) or targeted agents (N = 4611). All CVAEs, non-cardiac immune-related adverse events occurring after treatment initiation, baseline comorbidities, and treatment details were identified and analyzed using diagnosis and billing codes.

Results

Median age was 61 and 65 years in the ICI and non-ICI cohorts, respectively (P < 0.001). ICI patients were predominantly male (P < 0.001). Lung cancer (43.1%), melanoma (30.4%), and renal cell carcinoma (9.9%) were the most common cancer types. CVAE diagnoses in our dataset by incidence proportion (ICI cohort) were stroke (4.6%), heart failure (3.5%), atrial fibrillation (2.1%), conduction disorders (1.5%), myocardial infarction (0.9%), myocarditis (0.05%), vasculitis (0.05%), and pericarditis (0.2%). Anti-cytotoxic T-lymphocyte-associated protein 4 increased the risk of heart failure [versus anti-programmed cell death protein 1; hazard ratio (HR), 1.9; 95% confidence interval (CI) 1.27-2.84] and stroke (HR, 1.7; 95% CI 1.3-2.22). Pneumonitis was associated with heart failure (HR, 2.61; 95% CI 1.23-5.52) and encephalitis with conduction disorders (HR, 4.35; 95% CI 1.6-11.87) in patients on ICIs. Advanced age, primary cancer, nephritis, and anti-cytotoxic T-lymphocyte-associated protein 4 therapy were commonly associated with CVAEs in the adjusted Cox proportional hazards model.

Conclusions

Our findings underscore the importance of risk stratification and cardiovascular monitoring for patients on ICI therapy.

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Patient claims data across the United States were used to study cardiovascular adverse events (CVAEs) after ICI treatment.

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Patients on ICI treatment for advanced cancer have a higher incidence of CVAEs than previously reported.

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Median time to CVAE onset was significantly shorter with ICIs (~3 months) than with non-ICI systemic therapy (~8 months).

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Anti-CTLA-4 monotherapy or combination had a higher risk of heart failure and stroke than anti-PD-1 therapy (1.5-2 folds).

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Age, male sex, cancer type, nephritis, pneumonitis, and anti-CTLA-4 therapy were associated with a higher risk of CVAEs.

Continental crust formation on early Earth controlled by intrusive magmatism

The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature and more intense juvenile magmatism than in the present-day Earth, two crust-mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism and the "Plutonic squishy lid" tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus. Both tectonics regimes are capable of producing primordial tonalite-trondhjemite-granodiorite (TTG) continental crust but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data (low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.

Nasopharyngeal non-intestinal-type adenocarcinoma: a case report and updated review of the literature

BACKGROUND

Non-intestinal-type adenocarcinoma is a malignancy traditionally found in the sinonasal cavity. To our knowledge, this case is the first reported of this rare condition originating in the nasopharynx.

CASE PRESENTATION

A 67-year-old woman with nasopharyngeal non-intestinal-type adenocarcinoma, with an accompanying parapharyngeal mass received primary radiation treatment for both lesions. Her tumour subsequently persisted, with a concomitant conversion in pathology from a low- to a high-grade malignancy.

RESULTS

Non-intestinal-type and intestinal-type adenocarcinomas of the nasopharynx are extremely rare tumours and do not appear in the World Health Organization classification system. We review the pathophysiologic features of these malignancies and propose modifications to the current classification system.

CONCLUSIONS

Non-intestinal-type adenocarcinoma should be included in the differential diagnosis of nasopharyngeal masses. In our experience, this tumour in this location showed a partial response to primary radiation but later converted from a low- to a high-grade adenocarcinoma.

Enhanced Permeation of an Antiemetic Drug from Buccoadhesive Tablets by Using Bile Salts as Permeation Enhancers: Formulation Characterization, In Vitro, and Ex Vivo Studies

Buccal bioadhesive bilayer tablets of prochlorperazine maleate were designed and formulated by using buccoadhesive polymers such as hydroxypropylmethyl cellulose, Carbopol 934P, and sodium alginate. Physicochemical characteristics like the uniformity of weight, hardness, thickness, surface pH, drug content, swelling index, microenvironment pH, in vitro drug release, and in vivo buccoadhesion time of the prepared tablets were found to be dependent on the type and composition of the buccoadhesive materials used. The effect of bile salts on the permeation was studied through porcine buccal mucosa and it was found that out of three bile salts incorporated (sodium glycholate, sodium taurocholate, and sodium deoxycholate), sodium glycholate enhanced the permeation rate of prochlorperazine maleate by an enhancement factor of 1.37.

Carvedilol-?-cyclodextrin Systems: Preparation, Characterization and in vitro Evaluation

The purpose of this study was to improve the solubility and dissolution rate of carvedilol by forming a complex with ?-cyclodextrin. Phase solubility diagrams revealed increase in solubility of the drug upon cyclodextrin addition, showing AN type curve. Complexation of carvedilol was carried out with ?-cyclodextrin by physical mixing, kneading and co-precipitation method. The prepared complexes and physical mixture were characterized by Fourier transform infra red spectroscopy, differential scanning calorimetry, powder X-ray diffractometry and inclusion efficiency. It was also observed that the complexes exhibit higher dissolution rates than the pure drug and physical mixture. Among all carvedilol-cyclodextrin complexes, inclusion complex (1:5) prepared by co-precipitation method showed better release. Dhaka Univ. J. Pharm. Sci. 12(1): 51-58, 2013 (June) DOI: http://dx.doi.org/10.3329/dujps.v12i1.16300

Conjunctival impression cytology in computer users

Introduction:It is known that the computer users develop the features of dry eye. Objective: To study the cytological changes in the conjunctiva using conjunctival impression cytology in computer users and a control group. Materials and methods: Fifteen eyes of computer users who had used computers for more than one year and ten eyes of an age-and-sex matched control group (those who had not used computers) were studied by conjunctival impression cytology. Results: Conjunctival impression cytology (CIC) results in the control group were of stage 0 and stage I while the computer user group showed CIC results between stages II to stage IV. Among the computer users, the majority ( > 90 %) showed stage III and stage IV changes. Conclusion: We found that those who used computers daily for long hours developed more CIC changes than those who worked at the computer for a shorter daily duration. Nepal J Ophthalmol 2013; 5(9):33-37 DOI: http://dx.doi.org/10.3126/nepjoph.v5i1.7819

Comparison of astigmatism following manual small incision cataract surgery: superior versus temporal approach

INTRODUCTION

Now-a-days, all techniques of cataract extraction are meant for giving the best uncorrected visual acuity and early post-operative rehabilitation.

PURPOSE

To compare astigmatism induced by the superior and temporal section in manual small incision cataract surgery (SICS) in the Indian population.

MATERIALS AND METHODS

One hundred and ten eyes were taken. Eyes having a steeper vertical keratometry reading were assigned to the superior SICS group whereas eyes with a steeper horizontal keratometry reading were assigned to the temporal SICS group. Eyes with no astigmatism were randomly assigned to either of the two groups. Both the groups had 54 eyes each. Eyes in Group 1 underwent manual SICS with a superior tunnel and eyes in Group 2 underwent manual SICS with a temporal tunnel. The patients were examined on postoperative Day1, 1 week, 45 days, and 3 months. Uncorrected and best-corrected visual acuity was recorded, slit-lamp examination, auto-refracto-meter and keratometry examinations were done.

STATISTICS

All calculations were performed using surgically-induced astigmatism (SIA) Calculator version 1.0, a free software program.

RESULTS

In Group 2, only 35 eyes out of 54 completed the follow-up of 90 days. The mean SIA in Group1 was found to be 1.45 +/- 0.7387 and in Group 2 it was 0.75+/- 0.4067. The z score applied was found to be 5.7143. This value was more than the standard value, i.e.2.58. The p value accordingly was less than 0.001, which is highly significant. The SIA induced by the superior incision was 48.28 % more than by the temporal incision.

CONCLUSION

SICS with the temporal approach provides a better stabilization of the refraction with a significantly less SIA than superior approach.

Cavernous lymphangioma of eyelid - a rare case report

BACKGROUND

Lymphangioma is a lymphatic malformation, a benign proliferation of lymph vessels.

CASE

We hereby present a case of eyelid lymphangioma of cavernous type in a twelve year old male patient. This is a very uncommon site for this type of lymphangioma.

Terrien's marginal degeneration: an unusual presentation in an indian female

An interesting case of bilateral corneal ectasia resulting from its marginal degeneration in a young female is reported. Terriens marginal degeneration is a rare disorder of unknown etiology. It is usually bilateral, although often asymmetric, and is seen mainly in young men. It generally starts superiorly as marginal opacification and stromal thinning. This case was unique in that, unlike routine presentation seen in this type of disorder, the gutter was located more anteriorly in the cornea and was not associated with any vascularization.

Identification of multicopy suppressors of the pcnB plasmid copy number defect in Escherichia coli

Plasmids containing a ColE1 origin of replication are widely used for cloning purposes in Escherichia coli. Among the host factors that affect the copy number of ColE1 plasmids is the E. coli protein poly(A) polymerase I (PAP I), which regulates the intracellular level of RNA I, a ColE1-encoded negative regulator of plasmid replication. In strains that lack PAP I, RNA I levels are elevated, resulting in reduced levels of ColE1 plasmids in the cell. PAP I is encoded by the gene pcnB. We devised a genetic approach, based on the identification of multicopy suppressor clones, to identify trans-acting factors that can help offset the ColE1 plasmid copy number defect in a pcnB (-) genetic background. Using this strategy, we identified suppressors that mapped to two regions of the E. coli chromosome. The suppressor activity of one of the chromosomal regions was localized to the rssB gene, a response regulator gene known to be involved in the turnover of the stationary-phase sigma factor, RpoS. The second suppressor maps to min 55.4 of the E. coli chromosome, and the factor responsible for the suppressor activity appears to be a novel RNA or protein.

Structural model for the cooperative assembly of HIV-1 Rev multimers on the RRE as deduced from analysis of assembly-defective mutants

The functional efficacy of the HIV-1 Rev protein is highly dependent on its ability to assemble onto its HIV-1 RNA target (the RRE) as a multimeric complex. To elucidate the mechanism of multimeric assembly, we have devised two rapid and broadly applicable strategies for examining cooperative interactions between proteins bound to RNA, one based on cooperative translational repression of a two-site reporter and the other on gel shift analysis with crude E. coli extracts. Using these strategies, we have identified two distinct surfaces of Rev (head and tail) that are critical for different steps in multimeric assembly. Our data indicate that Rev assembles cooperatively on the RRE via a series of symmetrical tail-to-tail and head-to-head protein-protein interactions. The insights into molecular architecture suggested by these findings have enabled us to derive a structural model for Rev and its multimerization on the RRE.

Leuconychia totalis

A case of leukonychia totalis in a 20-year old. healthy man which manifested at the age of 2 years after an episode of acute illness is being reported.

An evolutionarily conserved RNA stem-loop functions as a sensor that directs feedback regulation of RNase E gene expression

RNase E is a key regulatory enzyme that controls the principal pathway for mRNA degradation in Escherichia coli. The cellular concentration of this endonuclease is governed by a feedback mechanism in which RNase E tightly regulates its own synthesis. Autoregulation is mediated in cis by the 361-nucleotide 5' untranslated region (UTR) of rne (RNase E) mRNA. Here we report the determination of the secondary structure of the rne 5' UTR by phylogenetic comparison and chemical alkylation, together with dissection studies to identify the 5' UTR element that mediates autoregulation. Our findings reveal that the structure and function of the rne 5' UTRs are evolutionarily well conserved despite extensive sequence divergence. Within the rne 5' UTRs are multiple RNA secondary structure elements, two of which function in cis to mediate feedback regulation of rne gene expression. The more potent of these two elements is a stem-loop structure containing an internal loop whose sequence is the most highly conserved of any region of the rne 5' UTR. Our data show that this stem-loop functions as a sensor of cellular RNase E activity that directs autoregulation by modulating the degradation rate of rne mRNA in response to changes in RNase E activity.

RNA recognition by the joint action of two nucleolin RNA-binding domains: genetic analysis and structural modeling

The interaction of nucleolin with a short stem-loop structure (NRE) requires two contiguous RNA-binding domains (RBD 1+2). The structural basis for RNA recognition by these RBDs was studied using a genetic system in Escherichia coli. Within each of the two domains, we identified several mutations that severely impair interaction with the RNA target. Mutations that alter RNA-binding specificity were also isolated, suggesting the identity of specific contacts between RBD 1+2 amino acids and nucleotides within the NRE stem-loop. Our data indicate that both RBDs participate in a joint interaction with the NRE and that each domain uses a different surface to contact the RNA. The constraints provided by these genetic data and previous mutational studies have enabled us to propose a three-dimensional model of nucleolin RBD 1+2 bound to the NRE stem-loop.

Models for pairing of IS10 encoded antisense RNAs in vivo

Antisense regulation of IS10 transposase synthesis is mediated by a small RNA molecule, RNA-OUT which is complementary to the 5' region of the IS10 transposase mRNA, RNA-IN. Pairing between the two species in vivo prevents initiation of RNA-IN translation by steric occlusion of the ribosome binding site. The goal of this work is to develop a mathematical basis for antisense repression in vivo. Thus, by modeling antisense pairing as a biomolecular reaction in vivo, I have developed equations which relate the degree of translation inhibition to a relative pairing rate constant, k, and the in vivo RNA-OUT concentration. Using the methodology developed here, an analysis of mutations in the first three 5' bases of RNA-IN reveals a semi-logarithmic relationship between k and delta G, the estimated change in the free energy of pairing. Such correlations are not observed for mutations at other positions, implicating only the first three 5' bases of RNA-IN in the formation of a pairing nucleus with RNA-OUT. Finally, an analysis of mutations that affect antisense action at a post-nucleation step has been undertaken here and a specific model for how these mutations may affect antisense pairing is discussed.

A structural model for the HIV-1 Rev-RRE complex deduced from altered-specificity rev variants isolated by a rapid genetic strategy

A broadly applicable genetic strategy was developed for investigating RNA-protein interactions and applied to the HIV-1 Rev protein. By rapidly screening thousands of Rev-RNA interactions in Escherichia coli, we isolated Rev suppressor mutations that alleviated the deleterious effect of mutations in RRE stem-loop IIB, the high affinity RNA-binding site for Rev. All of these suppressor mutations map to a single arginine-deficient face of a Rev alpha-helix, and some alter the binding specificity of the protein, providing genetic evidence for direct contacts between specific Rev amino acids and RNA nucleotides in the RNA complex of Rev. The spatial constraints suggested by these data have enabled us to model the structure of this complex.

Atypical manifestations of tinea faciei

A study of 58 paitents of tinea faciei was conducted. Twenty five (43.1%) patients had history of photosensitivity. Twenty eight (48.2%) patients were applying topical steroids, 2 (3.4%) patients were on 10 mg of prednisolone daily. Associated tinea of other sites were observed in 14 (24.13%). 23 (39.6%) patients had typical circinate, arcuate, annular plaques with raised margin showing vesiculo-pustules. Atypical manifestations were in the form of arcuate plaques on the pinna in 4 patients, erythematous plaques full of vesiculo-pustules without central clearing in 3. Thirty two (55.17%) patients had plaques with broad edges and indistinct central clearing. In 2 patients lesions resembled discoid lupus erythematosus. Skin scrapings for fungus was positive in 36 (62.06%) cases. All patients responded to systemic griseofulvin 10mg/kg with 1% clotrimazole topicaly in 4-8 weeks.

Unusual clinical and histopathological presentation of facial tuberculosis

Atypical facial lupus vulgaris is described in two cases. The first case resembled sarcoidosis clinically and histologically but responded well to ATT. The second case whose clinical diagnosis of lupus vulgaris was confirmed therapeutically had an atypical histology.

Preparation and characterization of niosomes containing rifampicin for lung targeting

Niosomes (non-ionic, surfactant-based vesicles) containing rifampicin of 8-15 microns in diameter were prepared using Span-85 and cholesterol in various molar fractions. The process variables that could affect the physical characteristics of niosomes and in vitro release of the drug from the niosomes were studied and optimized. In vivo distribution studies of the prepared niosomes found that 65% of the drug could be localized in the lungs by controlling the niosome size.

IS10 antisense control in vivo is affected by mutations throughout the region of complementarity between the interacting RNAs

Translation of the IS10 transposase mRNA (RNA-IN) is inhibited by antisense pairing with a small IS10 encoded transcript called RNA-OUT. To further characterize IS10 antisense control, an extensive set of mutations in the region of complementarity between RNA-OUT, and its target RNA-IN have been isolated. These mutations have been characterized for their effects on antisense inhibition of transposase gene translation in vivo. Mutations that confer the strongest defects on translational inhibition are found in the region corresponding to the 5' end of RNA-IN. However, mutations throughout the complementary region affect antisense control regardless of whether mutations are present in RNA-IN alone or as complementary mutations in both RNAs. An analysis of the data presented here suggests that in vivo pairing rates for the wild-type antisense species are very close to being optimal. Some of the motifs found in antisense molecules that may be associated with efficient pairing rates are discussed.

Drug-induced pseudolymphoma syndrome

Five cases of pseudolymphoma syndrome (PS) in children aged six to twelve years were observed after anticonvulsant drugs. In two cases PS was observed after ten days and in three after fifteen days of therapy with the offending drug. Three cases of PS were due to carbamazepine and had morbilliform rash and two cases due to phenobarbitone had erythroderma. All had fever, generalised lymphadenopathy and 4/5 had hepatosplenomegaly. Therapy with 15 mg prednisolone daily and withdrawal of the offending durg led to cure in 4/5 cases and one died due to congestive cardiac failure.

Autoregulation of RNase E synthesis in Escherichia coli

RNase E plays a central role in controlling mRNA degradation in E. coli. We have investigated the mechanism of RNase E autoregulation. Our data indicate that RNase E autoregulates its synthesis by controlling the decay rate of its own transcript (rne mRNA), which is unusually sensitive to the level of cellular RNase E activity. Feedback regulation is mediated in cis by the rne 5' untranslated region (5' UTR), which can confer this property onto heterologous mRNAs to which it is fused. The marked sensitivity of rne mRNA to regulation by RNase E is also due in part to the susceptibility of nascent rne transcripts to RNase E-mediated degradation.

Recurrent herpes zoster in a child with SLE

A 12-year-old girl had systemic lupus erythematosus (SLE) and type IV lupus nephritis since three-and-a-half years. She was treated with prednisolone and cyclophosphamide. She had first attack of herpes zoster (HZ) involving eighth and ninth thoracic segments on right side at the age of nine years. Second attack occurred on the same segments on same side at the age of twelve years. The second attack of herpes zoster was treated with oral acyclovir 400 mg five times a day for seven days plus analgesics and multi-vitamins. Most probably this is the first case of recurrent herpes zoster (RHZ) in a child in Indian literature.

RNase E autoregulates its synthesis by controlling the degradation rate of its own mRNA in Escherichia coli: unusual sensitivity of the rne transcript to RNase E activity

RNase E is a key regulatory enzyme that appears to control the principal pathway for mRNA degradation in Escherichia coli. Here, we show that RNase E represses its own synthesis by reducing the cellular concentration of the rne (RNase E) gene transcript. Autoregulation is achieved by modulating the longevity of this 3.6-kb mRNA, whose half-life ranges from < 40 sec to > 8 min depending on the level of RNase E activity in the cell. Feedback regulation is mediated in cis by the 5'-terminal 0.44-kb segment of rne mRNA, which is sufficient to confer this property onto a heterologous transcript to which it is fused. Like the intact protein, an amino-terminal fragment of RNase E lacking 563 amino acid residues can act in trans to repress rne gene expression. Paradoxically, raising the rne gene copy number 21-fold in E. coli causes an unexpected reduction in the concentration of the full-length rne transcript, yet results in a small increase in RNase E protein production. These surprising phenomena are explained in terms of a model in which the degradation of this long and highly labile mRNA commences before elongation of the nascent transcript has been completed. In such circumstances, gene expression can be unusually sensitive to changes in mRNA stability.

New improved lacZ gene fusion vectors

New plasmid vectors suitable for creating fusions with the lacZ gene have been developed. These vectors represent an improvement over currently available vectors and possess the following features: (1) an undetectable background beta-galactosidase (beta Gal) activity in the absence of fusion, (2) an extended multiple cloning site (MCS), and (3) the ability to conveniently subclone in any one of three translational frames. Medium- and high-copy-number versions of these vectors have been developed.

Preferential cis action of IS10 transposase depends upon its mode of synthesis

A number of bacterial DNA-binding proteins, including IS element transposases, act preferentially in cis. We show below that the degree of preferential cis action by IS10 transposase depends upon its mode of synthesis at steps subsequent to transcription initiation. Cis preference is increased several fold by mutations that decrease translation initiation, by the presence of IS10-specific antisense RNA and by plasmids that increase the level of cellular RNases. Conversely, cis preference is decreased by mutations that increase translation initiation; in some cases, cis preference is nearly abolished. Mutations that alter the rate of transcription initiation have no effect. In light of other observations, we suggest that cis preference is strongly dependent upon the rate at which transcripts are released from their templates and/or the half-life of the transposase message. These observations provide further evidence that inefficient translation plays multiple roles in the biology of IS10.

IS10 mRNA stability and steady state levels in Escherichia coli: indirect effects of translation and role of rne function

Translation of the IS10 transposase gene is known to be very infrequent. We have identified mutations whose genetic properties suggest that they act directly to increase or decrease the intrinsic level of translation initiation. Also, we have analysed in detail the effects of these mutations on IS10 mRNA using one particular IS10 derivative. In this case, increases or decreases in translation are accompanied by increases or decreases in both the steady state level and the half-life of transposase mRNA; effects on steady state levels are much more dramatic than effects on message half-life. At wild-type levels of translation initiation, the rate-limiting step in physical decay of full length IS10 message for a particular IS10 derivative is shown to be rne-dependent endonucleolytic cleavage; 3' exonucleases appear to play a secondary role, degrading primary cleavage products. Analysis of interplay between translation mutations and rne function, together with the above observations, suggests that translation stabilizes messages in a general way against rne-dependent endonucleolytic cleavage, and that significant protection may be conferred by one or a few ribosomes. However, dramatic effects of translation on steady state message levels are still observed in an rne mutant and involve the 3' end of the transcript; we propose that these additional effects reflect translation-mediated stimulation of transcript release.

Bioadhesive polymer-grafted starch microspheres bearing isosorbide dinitrate for buccal administration

A polymer-grafted mucoadhesive system bearing isosorbide dinitrate was prepared for buccal administration. Polymer grafting of starch microspheres modified drug release and surface characteristics of microspheres. Bioadhesion and factors affecting bioadhesion were studied. Process variables that could affect microsphere size, and as a result the release of the drug, were also studied. It was observed that compression of grafted starch microspheres modified drug release and extended drug action via slow release following buccal application. Prepared system(s) were characterized for drug release and in vivo performance and compared with conventional oral treatment. The systems were noted to be promising.

Polymeric pseudolatices bearing pilocarpine for controlled ocular delivery

The pseudolatex-based ocular formulations of pilocarpine were prepared using different combinations of Eudragit RS 100 and polyvinyl pyrrolidone for prolonged and controlled release of the drug. The designed system was essentially based on polymeric pseudolatex dispersion. The process variables that effect the latex particle size, drug loading and release profiles of drug were studied. Preparations were evaluated for their in vitro performance with regard to release profile and diffusion co-efficient. The designed system exhibited linear relationship between cumulative drug release (Q) and square root of time (t0.5). The products selected on the basis of in vitro characterization were studied for in vivo performance evaluation. It was observed that the preparations exhibited in vivo prolonged therapeutic efficacy. Thus polymer based pseudolatices hold promise for controlled pilocarpine ocular delivery.