A 22-pole radiofrequency ion trap setup for laboratory astrophysical studies

The formation of large interstellar molecules starting from small reactants constitutes the bottom-up approach in astrochemistry. An experimental setup wherein the ionic reactant is prepared and allowed to react with neutral reactants within a confined interaction space is most desirable for this approach. Here, we present our efforts in constructing a 22-pole radio-frequency ion trap experimental setup that could act as a reaction chamber for the neutral reactant and trapped ions. A compact piezo-based pulsed supersonic expansion discharge source was developed to achieve efficient production of anions, particularly metal-bearing ions. In addition, two other ion sources, namely, the electron impact ion source and the plasma supersonic discharge ion source, were developed to cater to the production of specific ions. The geometry of this experimental setup facilitates photo excitation of trapped ions. The trapping efficiency was studied by trapping SF5+ and SF6- for a few seconds. The control exhibited by various parameters on the efficiency of the trapping is discussed in detail. Potential studies that could be performed with this new experimental setup are also discussed.

Management of Length Unstable Femur Fractures in Children by Flexible Intramedullary Nails: A Systematic Review

PURPOSE OF THE STUDY

Surgical options for paediatric femoral fractures include fl exible intramedullary nailing (FIN), plating, and external fi xators. Length unstable fractures are usually spiral, long oblique, or comminuted and are often associated with > 2 cm of shortening. The purpose of this study was to see whether FIN is effective for managing unstable femur fractures in children.

MATERIAL AND METHODS

An electronic literature search was performed up to 25 February 2022 in Cochrane Library, PubMed, and Embase databases using a combination of MeSH search terms and keywords related to the population (e.g., "child" AND "diaphyses" AND "femur"), and intervention (e.g., "nail" OR "ESIN"). The data extracted included the study details, Demographic data, surgical details, postoperative immobilization, complications, and outcome.

RESULTS

Eight studies with a total sample size of 369 patients were reviewed. The mean operative time, blood loss, and length of stay in the hospital were 67.62±12.32 minutes, 33.82±16.82 ml, and 4.9±1.27 days, respectively. The results were excellent in 61.92% of the patients, satisfactory in 32.61%, and poor in 5.43%. 4.54% of patients had major complications requiring reoperation and 32.46% of patients had minor complications. the most common complication was nail prominence seen in 26.30% of patients. Locked Ender's nail was associated with the least reoperation, malunion, and LLD rate compared to other types of FIN.

CONCLUSIONS

FIN along with a single walking spica cast is a good choice in all forms of paediatric femoral fracture patterns allowing proper alignment and rotation. Locked Ender's nail is safe and effective for managing unstable paediatric femur fracture.

KEY WORDS

pediatric femur fracture, length unstable, fl exible intramedullary nailing, submuscular plating, Flynn criterion.

Molecular growth of PANH via intermolecular Coulombic decay

Nitrogen-bearing polycyclic aromatic hydrocarbons (PANHs) are ubiquitous in space. They are considered precursors to advanced biomolecules identified in meteorites. However, their chemical evolution into biomolecules in photodestructive astrophysical mediums remains a paradox. Here, we show that light can efficiently initiate the molecular mass growth of PANHs. Ultraviolet-photoexcited quinoline monomers, the smallest PANH, were observed to associate and intermolecular Coulombic decay between the associating monomers formed the cations of quinoline-dimer. Molecular rearrangements in the dimer cation lead to a dominant formation of cations heavier than quinoline. The enrichment of these heavier cations over all the other cations reveals the efficiency of this route for the mass growth of PANHs in space. This mechanism also leads to a highly reactive unsaturated PANH-ring via CH loss, a hitherto unknown channel in any photon-driven process. The occurrence of this efficient pathway toward complex molecules points to a rich chemistry in dense interstellar clouds.

A systematic review of complications following selective dorsal rhizotomy in cerebral palsy

PURPOSE

The literature lacks a concise overview of complications secondary to selective dorsal rhizotomy (SDR). The aim of this study was to systematically review the literature regarding post-SDR complications, and to present them concisely.

METHODS

The protocol of the review was registered on Open Science Framework. Studies on SDR in cerebral palsy were included. The studies to be included used SDR for management of spasticity in patients with cerebral palsy. The long-term complications of SDR mentioned in the articles were inventoried.

RESULTS

Thirty studies were included for qualitative review. Twenty-one types of complication were identified. Structural complications were the commonest: scoliosis (214/1,043, 20.5%), hyperlordosis (101/552, 18.2%), spondylolysis (55/574, 9.5%) and kyphosis (67/797, 8.4%). Neurological complications comprised constipation (70/485, 14.4%), hip subluxation (3/29, 10.3%), spastic syndrome (4/47, 8.5%), sensory changes (106/1290, 8.2%) and urinary incontinence (61/1013, 6%).

CONCLUSION

This review should help surgeons and parents alike to know about the potential complications of SDR. Complications may affect quality of life and should be weighed. Although the majority of these complications were managed conservatively, there would still be a physical, psychological and financial burden which should be taken into account. Screening should be continued vigorously throughout skeletal growth and at reduced frequency thereafter, for timely intervention in case of structural complications.

A Meta-Analysis on Comparison of Open vs Closed Reduction of Gartland Type 3 Supracondylar Humerus Fractures in Children

PURPOSE OF THE STUDY Although there are numerous studies on outcomes and comparison of open and closed reduction but there is no clarity on relationship between outcomes and complications with type of surgical intervention done for Type 3 Gartland supracondylar humerus fracture. The aim of this study is to compare the outcomes and complications of closed vs open reduction in Type 3 Gartland supracondylar humerus fractures. MATERIAL AND METHODS Electronic literature searches of Embase, MEDLINE and the Cochrane Library was conducted in February 2022 using the terms "supracondylar", "humerus", "fracture", "Gartland type 3" and synonymous. The data extracted included the study details, demographic data, procedure performed, final functional and cosmetic outcome according to Flynn criteria and complications of included studies. RESULTS Pooled data analysis revealed no significant difference in mean satisfactory outcome rate according to Flynn cosmetic criteria in open group (97%, 95% CI 95.5%-98.5%), as compared to closed group (97.5%, 95% CI 96.3%-98.7%), although a statistically significant difference in mean satisfactory rate according to Flynn functional criteria in open group (93.4%, 95% CI 90.8%- 96.1%) as compared to closed group (98.5%, 95% CI 97.5%-99.4%) was noted. On separate comparison of the two-arm studies, closed reduction favoured better functional outcomes (RR 0.92, 95% CI 0.86-0.99). CONCLUSIONS Closed reduction and percutaneous fixation have better functional outcome than open reduction with K-wire fixation. But there was no significant difference in cosmetic outcomes, overall complication rate and nerve injury with either open or closed reduction. The threshold of converting a closed reduction to an open reduction in supracondylar humerus fractures of children should be high. Key words: supracondylar humerus, open reduction, percutaneous pinning, Flynn criteria.

Ambient-light-induced intermolecular Coulombic decay in unbound pyridine monomers

Intermolecular Coulombic decay (ICD) is a process whereby photoexcited molecules relax by ionizing their neighbouring molecules. ICD is efficient when intermolecular interactions are active and consequently it is observed only in weakly bound systems, such as clusters and hydrogen-bonded systems. Here we report an efficient ICD between unbound molecules excited at ambient-light intensities. On the photoexcitation of gas-phase pyridine monomers, well below the ionization threshold and at low laser intensities, we detected the parent and heavier-than-parent cations. The isotropic emission of slow electrons revealed ICD as the underlying process. π-π* excitation in unbounded pyridine monomers triggered an associative interaction between them, which leads to an efficient three-centre ICD. The cation resulting from the molecular association of the three pyridine centres relaxed through fragmentation. This below-threshold ionization under ambient light has implications for the understanding of radiation damage and astrochemistry.

Results of ala carte Posteromedial Soft Tissue Release in Idiopathic Clubfoot

Introduction

The aim of this study is to assess the outcomes of ala carte posteromedial release in children over two years of age who were not responding to the Ponseti method of treatment of idiopathic clubfoot.

Material and Methods

A retrospective observational study from September 2013 to August 2015 was conducted at a tertiary level medical teaching institution. The clubfeet were classified according to the Harold and Walker classification. Radiographic parameters assessed were the talocalcaneal angle (AP, lateral), talus-first metatarsal angle (AP, lateral) and calcaneal-fifth metatarsal angle. The scar and the functional score, according to Laaveg and Ponseti, were evaluated as outcome measures at the final follow-up.

Results

Twenty-four children with a mean age of 43.7 ± 24.7 months were enrolled in the study. There was a total of 36 clubfeet: 21 (65.6%) with a poor functional outcome; 12 (37.4%) with excellent to good scar in both horizontal and vertical components. There was a statistical significance between the pre-operative and post-operative radiological parameters (p<0.05). None of the patients presented with any limitation of activities of daily living despite the poor functional outcome in many of the children. There was no significant association between the qualities of scar (horizontal, vertical) and the functional outcome with age at presentation, pre-operative Harold and Walker classification and pre-operative radiographic angles.

Conclusion

Surgical intervention in terms of ala carte posteromedial soft tissue release could not produce a good outcome over four years in CTEV. The threshold for surgery in CTEV should be high, given the poor results.

Clinical benefits of concurrent capecitabine and cisplatin versus concurrent cisplatin and 5-flurouracil in locally advanced squamous cell head and neck cancer

We aimed to assess the efficacy and safety of concurrent capecitabine and cisplatin over concurrent cisplatin and 5-flurouracil (5-FU) in locally advanced squamous cell carcinoma of the head and neck. One hundred and fifty-three patients (all of whom had stage III or IV unresectable disease with no distant metastases and who had received two cycles of taxol and cisplatin chemotherapy) were randomly assigned to receive either concurrent cisplatin (75 mg/m(2) in day 1 and 2) and 5-FU (750 mg/m(2) in day 1, 2, and 3) from the first day of radiotherapy at an interval of 3 weeks (Arm I) or cisplatin (75 mg/m(2) in day 1 and 2) and capecitabine (750 mg/m(2) in two divided doses from day 1-14) from the first day of radiotherapy at a 3-week interval (Arm II). Results showed that patients in Arm II had a significantly better rate of complete response, fewer nodes, and better overall response compared to those in Arm I. The two groups had a similar 3-year disease-free survival, progression free survival, and overall survival, i.e. they did not differ significantly. Variables indicating the quality of life of the two groups were compared. Patients in Arm II had a significantly higher quality of life compared to those in Arm I. The two groups had similar treatment-related acute and late toxicity, i.e. they did not differ significantly. These results have thoroughly substantiated the contention that concurrent chemoradiation with capecitabine and cisplatin may be regarded as an effective and well-tolerated regimen in the treatment of the patients with locally advanced head and neck cancer.

Growth and characterization of self-assembled InAs/InP quantum dot structures

InAs quantum dots (QDs) are grown on InP or lattice matched GaInAsP buffers using horizontal flow metal-organic chemical vapor deposition (MOCVD) at a pressure of 180 mbar. A range of techniques, such as photoluminescence (PL), atomic force microscopy, and plan-view transmission electron microscopy is used to characterize the QD and other semiconductor layers. The effects of different growth parameters, such as V/III ratio and growth time, and the effects of buffer layers, interlayers, and cap layers are investigated and the optimized growth conditions are discussed. In the case of the QDs grown on InP buffers, the As/P exchange reaction is found to be prominent. A very thin (0.6 nm) GaAs interlayer grown between the buffer and the QD layers consumes segregated indium and minimizes the As/P exchange reaction. As a result, the QD PL emission energy increases, the PL intensity improves, and the PL linewidth decreases. The experimental results show that by changing the thickness of a GaAs interlayer (0.3-0.6 nm), the emission wavelength/energy of the QDs grown on a lattice matched GaInAsP buffer can be tuned over a wide range covering 1550 nm. However, further increase in the thickness of the GaAs interlayer results in the agglomeration of the QDs and the deterioration of the QD optical properties. Detailed microscopy studies show that capped QDs have higher density and are smaller in size on average compared to uncapped QDs, which undergo coalescence during cooling of the sample after growth. Overall, the QDs grown for shorter time with a smaller V/III ratio (approximately 8) show improved PL intensity and narrower PL linewidth.

Immunophilins: for the love of proteins

Immunophilins are chaperones that may also exhibit peptidylprolyl isomerase (PPIase) activity. This review summarizes our knowledge of the two largest families of immunophilins, namely cyclophilin and FK506-binding protein, and a novel chimeric dual-family immunophilin, named FK506- and cyclosporin-binding protein (FCBP). The larger members of each family are modular in nature, consisting of multiple PPIase and/or protein-protein interaction domains. Despite the apparent difference in their sequence and three-dimensional structure, the three families encode similar enzymatic and biological functions. Recent studies have revealed that many immunophilins possess a chaperone function independent of PPIase activity. Knockout animal studies have confirmed multiple essential roles of immunophilins in physiology and development. An immunophilin is indeed a natural 'protein-philin' (Greek 'philin' = friend) that interacts with proteins to guide their proper folding and assembly.

Construction of a pepO gene-deficient mutant of Porphyromonas gingivalis: potential role of endopeptidase O in the invasion of host cells

Porphyromonas gingivalis has been isolated from lesions of advanced adult periodontitis, and implicated as a periodontal pathogen. We have previously cloned a novel endopeptidase, designated PepO, from P. gingivalis 381, which exhibited significant homology to human endothelin-converting enzyme (ECE)-1. In order to determine the nature and function of the PepO in the host, a pepO gene-deficient mutant strain was constructed by allelic exchange mutagenesis using the ermF-ermAM cassette. No endopeptidase activity was detected in the pepO-deficient mutant. In addition, adherent HeLa (HEp-2) cells were infected with the mutant and the two wild-type strains for assessment of bacterial invasion by an antibiotic protection assay. The invasion efficiency of the mutant strain was about a quarter of the wild type strains. These results suggest that PepO is involved in the first step, i.e. invasion/lysis of mammalian cell membrane, which affects the kinetics of rate of invasion.

Site-directed mutagenesis by double polymerase chain reaction : megaprimer method

The "megaprimer" method (1) based on polymerase chain reaction (PCR) is one of the simplest and most versatile procedures of site-specific in vitro mutagenesis available to date. The method utilizes three oligonucleotide primers and two rounds of PCR performed on a DNA template containing the cloned gene that is to be mutated. The rationale of the method is shown schematically in Fig. 1 where A and B represent the "flanking" primers that can map either within the cloned gene or outside the gene (i.e., within the vector sequence) and M represents the internal "mutant" primer containing the desired base change. The first round of PCR is performed using the mutant primer (e.g., M1 in Fig. 1) and one of the flanking primers (e.g., A). The double-stranded product (A-M1) is purified and used as one of the primers (hence the name "megaprimer") in the second round of PCR along with the other flanking primer (B). The wild type cloned gene is used as template in both PCR reactions. The final PCR product (A-M1-B) containing the mutation can be used in a variety of standard applications, such as cloning in expression vectors and sequencing, or in more specialized applications, such as production of the gene message in vitro if primer A (or the template sequence downstream of primer A) also contains a transcriptional promoter (e.g., that of SP6 or T7 phage).

Visual inspection with acetic acid and cytology in the early detection of cervical neoplasia in Kolkata, India

Visual inspection of the cervix after application of 3-5% acetic acid (VIA) is a potential alternative to cytology for screening in low-resource countries. The present study evaluated the performance of VIA, magnified visual inspection after application of acetic acid (VIAM), and cytology in the detection of high-grade cervical cancer precursor lesions in Kolkata (Calcutta) and suburbs in eastern India. Trained health workers with college education concurrently screened 5881 women aged 30-64 years with VIA, VIAM, and conventional cervical cytology. Detection of well-defined, opaque acetowhite lesions close to the squamocolumnar junction; well-defined, circumorificial acetowhite lesions; or dense acetowhitening of ulceroproliferative growth on the cervix constituted a positive VIA or VIAM. Cytology was considered positive if reported as mild dysplasia or worse lesions. All screened women (N = 5881) were evaluated by colposcopy, and biopsies were directed in those with colposcopic abnormalities (N = 1052, 17.9%). The final diagnosis was based on histology (if biopsies had been taken) or colposcopic findings, which allowed direct estimation of sensitivity, specificity, and predictive values. Moderate or severe dysplasia or carcinoma in situ (CIN 2-3 disease) was considered as true positive disease for the calculation of sensitivity, specificity, and predictive values of screening tests. 18.7%, 17.7% and 8.2% of the women tested positive for VIA, VIAM, and cytology. One hundred twenty two women had a final diagnosis of CIN 2-3 lesions. The sensitivities of VIA and VIAM to detect CIN 2-3 lesions were 55.7% and 60.7%, respectively; the specificities were 82.1% and 83.2%, respectively. The sensitivity and specificity of cytology were 29.5% and 92.3%, respectively. All the tests were associated with negative predictive values above 98%. VIA and VIAM had significantly higher sensitivity than cytology in our study; the specificity of cytology was higher than that of VIA and VIAM.

Visual inspection with acetic acid and cytology in the early detection of cervical neoplasia in Kolkata, India

Visual inspection of the cervix after application of 3–5% acetic acid (VIA) is a potential alternative to cytology for screening in low-resource countries. The present study evaluated the performance of VIA, magnified visual inspection after application of acetic acid (VIAM), and cytology in the detection of high-grade cervical cancer precursor lesions in Kolkata (Calcutta) and suburbs in eastern India. Trained health workers with college education concurrently screened 5881 women aged 30–64 years with VIA, VIAM, and conventional cervical cytology. Detection of well-defined, opaque acetowhite lesions close to the squamocolumnar junction; well-defined, circumorificial acetowhite lesions; or dense acetowhitening of ulceroproliferative growth on the cervix constituted a positive VIA or VIAM. Cytology was considered positive if reported as mild dysplasia or worse lesions. All screened women (N = 5881) were evaluated by colposcopy, and biopsies were directed in those with colposcopic abnormalities (N = 1052, 17.9%). The final diagnosis was based on histology (if biopsies had been taken) or colposcopic findings, which allowed direct estimation of sensitivity, specificity, and predictive values. Moderate or severe dysplasia or carcinoma in situ (CIN 2–3 disease) was considered as true positive disease for the calculation of sensitivity, specificity, and predictive values of screening tests. 18.7%, 17.7% and 8.2% of the women tested positive for VIA, VIAM, and cytology. One hundred twenty two women had a final diagnosis of CIN 2–3 lesions. The sensitivities of VIA and VIAM to detect CIN 2–3 lesions were 55.7% and 60.7%, respectively; the specificities were 82.1% and 83.2%, respectively. The sensitivity and specificity of cytology were 29.5% and 92.3%, respectively. All the tests were associated with negative predictive values above 98%. VIA and VIAM had significantly higher sensitivity than cytology in our study; the specificity of cytology was higher than that of VIA and VIAM.

Characterization of a novel serine/threonine protein phosphatase (PfPPJ) from the malaria parasite, Plasmodium falciparum

A novel protein phosphatase cDNA of the PPP superfamily was identified from the malaria parasite, Plasmodium falciparum (Pf), and tentatively named PfPPJ. The predicted primary structure of the phosphatase contained all the known conserved motifs of the PPP superfamily essential for catalytic activity. The enzyme was specific for dephosphorylation of phosphoserine and phosphothreonine residues with very little activity against phosphotyrosine residues. However, the sequence at its C-terminal end was unique, and was consistent with its resistance to the classical PP2A-specific inhibitors such as okadaic acid and microcystin-LR, and the PP1-specific inhibitor, mammalian heat-stable inhibitor-2 (I-2). Even the catalytic core of PfPPJ had a sequence substantially different from the other PPPs such that PfPPJ could be placed in an apparently separate phylogenetic branch. At 294 amino acids residues, PfPPJ was one of the smallest okadaic acid-resistant PPP phosphatases known. By Northern blot analysis, the expression of the PfPPJ mRNA showed the following pattern: schizont > ring > trophozoite, which closely paralleled the expression of the protein, as determined by immunofluorescence. Together, these results suggested a parasitic stage-specific transcriptional regulation of this novel and potentially unique protozoan phosphatase.

Comparison of thyroid function in pregnant and non-pregnant Asian and western Caucasian women

BACKGROUND

Gestational thyrotoxicosis may be more prevalent in Asian women.

METHODS

We have measured thyroid function, ferritin and bone specific alkaline phosphatase (BALP) as peripheral markers of thyroid function and hCG in Asian and western Caucasian women in non-pregnant and early pregnancy.

RESULTS

TSH was lower in Asian women in non-pregnancy but not during normal pregnancy and this may reflect increased sensitivity of the thyroid gland to thyroid stimulation in the Asian population. No ethnic difference was found in FT3, FT4 or hCG but ferritin was lower and BALP higher in Asian women whether pregnant or not and this may be a reflection of iron balance and vitamin D status.

CONCLUSIONS

We found during normal pregnancy that dynamic patterns of change for thyroid hormones and hCG are not different in Asian and western Caucasian women. We have developed gestation related reference intervals, which are a pre-requisite to the study of ethnic differences in gestation thyrotoxicosis in pregnancy.

An endoplasmic reticulum-specific stress-activated caspase (caspase-12) is implicated in the apoptosis of A549 epithelial cells by respiratory syncytial virus

Respiratory syncytial virus (RSV) infection induced programmed cell death or apoptosis in the cultured lung epithelial cell line, A549. The apoptotic cells underwent multiple changes, including fragmentation and degradation of genomic DNA, consistent with the activation of the DNA fragmentation factor or caspase-activated DNase (DFF or CAD). The infection led to activation of FasL; however, a transdominant mutant of FAS-downstream death domain protein, FADD, did not inhibit apoptosis. Similarly, modest activation of cytoplasmic apoptotic caspases, caspase-3 and -8, were observed; however, only a specific inhibitor of caspases-3 inhibited apoptosis, while an inhibitor of caspase-8 had little effect. No activation of caspase-9 and -10, indicators of the mitochondrial apoptotic pathway, was observed. In contrast, RSV infection strongly activated caspase-12, an endoplasmic reticulum (ER) stress response caspase. Activation of the ER stress response was further evidenced by upregulation of ER chaperones BiP and calnexin. Antisense-mediated inhibition of caspase-12 inhibited apoptosis. Inhibitors of NF-kappa B had no effect on apoptosis. Thus, RSV-induced apoptosis appears to occur through an ER stress response that activates caspase-12, and is uncoupled from NF-kappa B activation.

Lack of significant morphological differences between human X and Y spermatozoa and their precursor cells (spermatids) exposed to different prehybridization treatments

Human X and Y spermatozoa were previously compared by several nonmolecular techniques. Recent studies show that in many of the previous investigations, the methods used to identify the spermatozoa were nonspecific and thus produced contradictory findings. In the present study, the comparison of the 2 germ cell types, X and Y, were performed following fluorescence in situ hybridization (FISH), which is the most reliable genotyping technique currently available. The FISH technique was performed under 3 different treatments: permeabilization with liquid N2, fixation with Carnoy's, and chromatin decondensation with lithium di-iodosalicylate. Mature and immature germ cells (spermatozoa and spermatids) were compared. Lithium showed higher hybridization efficiency, while liquid N2 and Carnoy's fixative maintained better morphological integrity of cells with lower hybridization. The sperm exhibiting hybridization signals were not different in any of the morphometric or qualitative comparisons from those that did not exhibit signals. No significant deviation of the sex ratio from 1:1 was seen in either the mature or immature germ cell population. The spatial distribution of X and Y chromosome-specific signals in the sperm head were identical. The hybridization treatments did not have any preferential effect on the cells of specific genotype (X or Y). Neither head parameters (length, HL; width, HW; area, HA) nor tail length (TL) significantly differed between X and Y populations of spermatozoa under any of the treatments. Similarly, the haploid, X-specific round cells did not differ from Y-specific ones by their size (diameter) and shape. These results indicate that neither mature sperm nor their precursors possess significant morphological differences between X and Y genotypes.

PfPK6, a novel cyclin-dependent kinase/mitogen-activated protein kinase-related protein kinase from Plasmodium falciparum

We have isolated a novel protein kinase cDNA, PfPK6, by differential display RT-PCR (DDRT-PCR) of mRNA obtained from different asexual erythrocytic stages of Plasmodium falciparum, which shows sequence similarity to both cyclin-dependent kinase (CDK) and mitogen-activated protein kinase (MAPK) family members. The 915 bp open reading frame (ORF) is interrupted by seven introns and encodes a 305-residue polypeptide with a predicted molecular mass of 35848 Da. Several cDNA clones with some of the intron sequences were isolated, indicating alternate or defective splicing of PfPK6 transcripts because the gene seems to be a single copy located on chromosome 13. The similarity of the catalytic domain of PfPK6 to those of CDK2 and MAPK is 57.3% and 49.6%, respectively. The signature PSTAIRE (single-letter amino acid codes) CDK motif is changed to SKCILRE in PfPK6. The TXY residues that are phosphorylated in MAPKs for their activation are T(173)PT in PfPK6. Three size classes of PfPK6 transcripts of 6.5, 2.0 and 1.1 kb are up-regulated during the transition of P. falciparum from ring to trophozoite. Western blot analysis suggested the expression of a 35 kDa polypeptide in trophozoites and schizonts. Immunofluorescence studies indicated both nuclear and cytoplasmic localization of PfPK6 in trophozoite, schizont and segmenter stages. In vitro, recombinant PfPK6 phosphorylated itself and also exogenous substrates, histone and the small subunit of the malarial ribonucleotide reductase (R2). The kinase activity of PfPK6 is sensitive to CDK inhibitors such as olomoucine and roscovitine. PfPK6 showed a preference for Mn(2+) over Mg(2+) ions as a cofactor. The Lys(38)-->Arg mutant is severely defective in its interaction with ATP and bivalent cations and somewhat defective in catalytic rate for R2 phosphorylation.

Profilin is required for optimal actin-dependent transcription of respiratory syncytial virus genome RNA

Transcription of human respiratory syncytial virus (RSV) genome RNA exhibited an obligatory need for the host cytoskeletal protein actin. Optimal transcription, however, required the participation of another cellular protein that was characterized as profilin by a number of criteria. The amino acid sequence of the protein, purified on the basis of its transcription-optimizing activity in vitro, exactly matched that of profilin. RSV transcription was inhibited 60 to 80% by antiprofilin antibody or poly-L-proline, molecules that specifically bind profilin. Native profilin, purified from extracts of lung epithelial cells by affinity binding to a poly-L-proline matrix, stimulated the actin-saturated RSV transcription by 2.5- to 3-fold. Recombinant profilin, expressed in bacteria, stimulated viral transcription as effectively as the native protein and was also inhibited by poly-L-proline. Profilin alone, in the absence of actin, did not activate viral transcription. It is estimated that at optimal levels of transcription, every molecule of viral genomic RNA associates with approximately the following number of protein molecules: 30 molecules of L, 120 molecules of phosphoprotein P, and 60 molecules each of actin and profilin. Together, these results demonstrated for the first time a cardinal role for profilin, an actin-modulatory protein, in the transcription of a paramyxovirus RNA genome.

Isolation, cloning, and expression of an acid phosphatase containing phosphotyrosyl phosphatase activity from Prevotella intermedia

A novel acid phosphatase containing phosphotyrosyl phosphatase (PTPase) activity, designated PiACP, from Prevotella intermedia ATCC 25611, an anaerobe implicated in progressive periodontal disease, has been purified and characterized. PiACP, a monomer with an apparent molecular mass of 30 kDa, did not require divalent metal cations for activity and was sensitive to orthovanadate but highly resistant to okadaic acid. The enzyme exhibited substantial activity against tyrosine phosphate-containing peptides derived from the epidermal growth factor receptor. On the basis of N-terminal and internal amino acid sequences of purified PiACP, the gene coding for PiACP was isolated and sequenced. The PiACP gene consisted of 792 bp and coded for a basic protein with an M(r) of 29,164. The deduced amino acid sequence exhibited striking similarity (25 to 64%) to those of members of class A bacterial acid phosphatases, including PhoC of Morganella morganii, and involved a conserved phosphatase sequence motif that is shared among several lipid phosphatases and the mammalian glucose-6-phosphatases. The highly conservative motif HCXAGXXR in the active domain of PTPase was not found in PiACP. Mutagenesis of recombinant PiACP showed that His-170 and His-209 were essential for activity. Thus, the class A bacterial acid phosphatases including PiACP may function as atypical PTPases, the biological functions of which remain to be determined.

Casein kinase 2-mediated phosphorylation of respiratory syncytial virus phosphoprotein P is essential for the transcription elongation activity of the viral polymerase; phosphorylation by casein kinase 1 occurs mainly at Ser(215) and is without effect

The major site of in vitro phosphorylation by casein kinase 2 (CK2) was the conserved Ser(232) in the P proteins of human, bovine, and ovine strains of respiratory syncytial virus (RSV). Enzymatic removal of this phosphate group from the P protein instantly halted transcription elongation in vitro. Transcription reconstituted in the absence of P protein or in the presence of phosphate-free P protein produced abortive initiation products but no full-length transcripts. A recombinant P protein in which Ser(232) was mutated to Asp exhibited about half of the transcriptional activity of the wild-type phosphorylated protein, suggesting that the negative charge of the phosphate groups is an important contributor to P protein function. Use of a temperature-sensitive CK2 mutant yeast revealed that in yeast, phosphorylation of recombinant P by non-CK2 kinase(s) occurs mainly at Ser(215). In vitro, P protein could be phosphorylated by purified CK1 at Ser(215) but this phosphorylation did not result in transcriptionally active P protein. A triple mutant P protein in which Ser(215), Ser(232), and Ser(237) were all mutated to Ala was completely defective in phosphorylation in vitro as well as ex vivo. The xanthate compound D609 inhibited CK2 but not CK1 in vitro and had a very modest effect on P protein phosphorylation and RSV yield ex vivo. Together, these results suggest a role for CK2-mediated phosphorylation of the P protein in the promoter clearance and elongation properties of the viral RNA-dependent RNA polymerase.

Importance of the beta12-beta13 loop in protein phosphatase-1 catalytic subunit for inhibition by toxins and mammalian protein inhibitors

Type-1 protein serine/threonine phosphatases (PP1) are uniquely inhibited by the mammalian proteins, inhibitor-1 (I-1), inhibitor-2 (I-2), and nuclear inhibitor of PP1 (NIPP-1). In addition, several natural compounds inhibit both PP1 and the type-2 phosphatase, PP2A. Deletion of C-terminal sequences that included the beta12-beta13 loop attenuated the inhibition of the resulting PP1alpha catalytic core by I-1, I-2, NIPP-1, and several toxins, including tautomycin, microcystin-LR, calyculin A, and okadaic acid. Substitution of C-terminal sequences from the PP2A catalytic subunit produced a chimeric enzyme, CRHM2, that was inhibited by toxins with dose-response characteristics of PP1 and not PP2A. However, CRHM2 was insensitive to the PP1-specific inhibitors, I-1, I-2, and NIPP-1. The anticancer compound, fostriecin, differed from other phosphatase inhibitors in that it inhibited wild-type PP1alpha, the PP1alpha catalytic core, and CRHM2 with identical IC(50). Binding of wild-type and mutant phosphatases to immobilized microcystin-LR, NIPP-1, and I-2 established that the beta12-beta13 loop was essential for the association of PP1 with toxins and the protein inhibitors. These studies point to the importance of the beta12-beta13 loop structure and conformation for the control of PP1 functions by toxins and endogenous proteins.

Analysis of in vitro migration patterns of human spermatozoa by a petri dish-based horizontal column

Spermatozoa are required to travel a considerable distance in vivo to meet the oocyte at the fertilization site. However, none of the existing in vitro tests critically evaluates migration of sperm to assess their potential of reaching the oocyte. On the other hand, an in vivo model is not suitable for this type of study because of ethical and technical constraints. In the present study we utilized a horizontal column technique to analyze sperm migration. Migratory characteristics of fresh, unwashed semen sperm and sperm undergoing various treatments were examined in vitro using a Petri dish-based horizontal fluid column. The procedure involved loading a sperm sample into the column and determining sperm concentration, motility, and viability at different column segments for different migration durations (6, 12, 24, 48, and 72 h). All sperm samples produced an exponential migration pattern in all durations of migration. Propagation along the column edge, tendency to exit from the column, and hiding in the blind pouches were some of the important characteristic features exhibited by the migratory sperm. Variations in migration patterns were documented among semen donors, between fresh and frozen semen, and between washed and unwashed sperm. Prolonged postejaculation time diminished migratory potential. The recovery of sperm in the column end was independent of seminal variables with the exception of oligozoospermia. These observations suggest that the Petri dish-based horizontal column is effective for analyzing sperm migration characteristics for prolonged periods. The potential of this migration assay in predicting the in vivo potential of spermatozoa to reach the fertilization site will be worth exploring.

Characterization of protein Ser/Thr phosphatases of the malaria parasite, Plasmodium falciparum: inhibition of the parasitic calcineurin by cyclophilin-cyclosporin complex

Two major protein phosphatase (PP) activities were purified from cytosolic extracts of the erythrocytic stage of the malaria parasite, Plasmodium falciparum. Both enzymes were specific for phosphoserine and phosphothreonine residues with very little activity against phosphotyrosine residues. The biochemical properties of the enzymes suggested their strong similarity with eukaryotic PP2A and PP2B protein phosphatases. Both enzymes preferentially dephosphorylated the alpha subunit of phosphorylase kinase, and were resistant to inhibitor-1. The PP2A-like enzyme required Mn2+ for activity and was inhibited by nanomolar concentrations of okadaic acid (OA). The cDNA sequence of the PP2A-like enzyme was identified through a match of its predicted amino acid sequence with the N-terminal sequence of the catalytic subunit. The PP2B-like (calcineurin) enzyme was stimulated by calmodulin and Ca2+ or Ni2+, but was resistant to OA. Malarial calcineurin was strongly and specifically inhibited by cyclosporin A (CsA) only in the presence of wild type P. falciparum cyclophilin but not a mutant cyclophilin. The inhibition was noncompetitive, and provides a potential explanation for the cyclosporin-sensitivity of the parasite. There was no significant quantitative difference in the total protein Ser/Thr phosphatase activity among the ring, trophozoite, and schizont stages.

Differential effect of common laboratory treatments on hypoosmotic swelling responses of human spermatozoa

PURPOSE

The impact of some of the common laboratory interventions on the hypoosmotic swelling (HOS) responses of human-spermatozoa was investigated.

METHODS

The semen samples underwent different laboratory treatments prior to the standard HOS test, which involved incubation of sperm in the hypoosmotic solution. Fresh semen served as a control for all treatment groups and underwent the same HOS procedure. The HOS-reactive spermatozoa and the type of HOS reactions (swelling types) in each group were identified under a phase-contrast microscope for comparison.

RESULTS

All the seven types of HOS responses documented in fresh semen sperm also occurred in the laboratory-processed sperm. The total HOS responses of sperm that underwent cryopreservation, heat shock, and Percoll wash were significantly different from those of the corresponding control. Percoll washing of semen influenced HOS subtypes a and g; cryopreservation affected subtypes a, b, c, and d; and heat shock altered subtypes a, f, and g. In contrast, prolonged postejaculation and cold shock did not affect any of the HOS responses. None of the treatments influenced the d and e responses.

CONCLUSIONS

These results indicate that the total HOS response value and specific response subtypes are significantly affected by some of the laboratory treatments but not others.

Role of cellular actin in the gene expression and morphogenesis of human respiratory syncytial virus

Cytoskeletal protein actin and nonactin cellular proteins were essential for human respiratory syncytial virus (RSV) gene expression. In vitro, specific antibodies against actin inhibited RSV transcription, whereas antibodies against other cytoskeletal proteins had little or no effect. Affinity purified cellular actin or bacterially expressed recombinant actin activated RSV transcription. However, optimal transcription required additional cellular protein(s) that appeared to function as accessory factor(s) for actin. In the absence of actin, these proteins did not activate viral transcription. Purified viral nucleocapsids contained actin, but no cytokeratin, tubulin, or vimentin. Cytochalasin D or DNasel--agents that destabilize actin polymers--had little effect on RSV transcription. RSV infection itself seemed to alter the structure of the cellular actin filaments. Treatment of infected cells with cytochalasin D produced a more severe disruption of the filaments and drastically reduced the production of infectious virus particles but still had little effect on intracellular synthesis of viral macromolecules. Thus actin seems to serve a dual role in RSV life cycle: its monomeric form as well as polymeric form activate viral transcription, while only the microfilament form may take part in viral morphogenesis and/or budding.

Inhibitor-1 interaction domain that mediates the inhibition of protein phosphatase-1

Inhibitor-1 (I-1), a cyclic AMP-regulated phosphoprotein, inhibits protein phosphatase-1 (PP1) activity in response to hormones. The molecular mechanism for PP1 inhibition by I-1 remains unknown. Mutation of nine acidic residues lining a proposed I-1-binding channel in rabbit PP1alpha yielded one mutant (E256A) slightly impaired in its inhibition by I-1, with the IC50 increased by 3-fold, and one mutant (E275R) located in the beta12-beta13 loop that showed 4-fold enhanced inhibition by I-1. Substituting Tyr-272, a proposed binding site for the toxins okadaic acid and microcystin-LR, in the beta12-beta13 loop with Trp, Phe, Asp, Arg, or Ala impaired PP1alpha inhibition by I-1 by 8-10-fold. Chemical mutagenesis of the Saccharomyces cerevisiae PP1 gene (GLC7) yielded 20 point mutations in the PP1 coding region. Two-hybrid analyses and biochemical assays of these yeast enzymes identified four additional residues in the beta12-beta13 loop that were required for PP1 binding and inhibition by I-1. Ten-fold higher concentrations of I-1 were required to inhibit these mutants. Finally, deletion of the beta12-beta13 loop from PP1alpha maintained full enzyme activity, but attenuated inhibition by I-1 by >100-fold. These data identified the beta12-beta13 loop in the PP1 catalytic subunit as a domain that mediates binding and enzyme inhibition by I-1.