Rice anther tapetum: a vital reproductive cell layer for sporopollenin biosynthesis and pollen exine patterning

The tapetum is the innermost layer of the four layers of the rice anther that provides protection and essential nutrients to pollen grain development and delivers precursors for pollen exine formation. The tapetum has a key role in the normal development of pollen grains and tapetal programmed cell death (PCD) that is linked with sporopollenin biosynthesis and transport. Recently, many genes have been identified that are involved in tapetum formation in rice and Arabidopsis. Genetic mutation in PCD-associated genes could affect normal tapetal PCD, which finally leads to aborted pollen grains and male sterility in rice. In this review, we discuss the most recent research on rice tapetum development, including genomic, transcriptomic and proteomic studies. Furthermore, tapetal PCD, sporopollenin biosynthesis, ROS activity for tapetum function and its role in male reproductive development are discussed in detail. This will improve our understanding of the role of the tapetum in male fertility using rice as a model system, and provide information that can be applied in rice hybridization and that of other major crops.

A qualitative insight into the perceptions and COVID-19 vaccine hesitancy among Pakistani pharmacists

A qualitative exploration of pharmacists’ perceptions regarding COVID-19 conspiracies and their willingness to get vaccinated. A semi-structured questionnaire guide was developed using ground theory to conduct in-depth interviews. A total of 36 participants gave consent for an audio-recorded interview. Results have shown that most of the respondents believed that SARS-CoV-2 is a natural virus, not man-made, that causes a disease just like other viruses and it is absurd to believe that the vaccine is being used by foreign powers for the implantation of microchips just to control humans. A general opinion thatwhich reflected from the in-depth interview is that the pharmaceutical companies may be hiding some important information on COVID-19 to promote the sale of their product. Some doubts on the reliability and trustworthiness on the COVID-19 vaccine safety and efficacy data were noticed among the respondents. Factors leading to COVID-19 vaccine hesitancy were adverse reaction, cost of COVID-19 vaccine, and limited data on safety and efficacy profile of COVID-19 vaccine. COVID-19 vaccine hesitancy among health professionals is a major hindrance to our current fight against COVID-19 pandemic. Findings of this study are alarming, and the stakeholders must consider this ongoing vaccination campaign as an opportunity to formulate a mechanism to ensure high vaccination rate among general public and healthcare providers in Pakistan.

KEY POINTS

What was already known?

According to World Health Organization (WHO), vaccine hesitancy is one of the ten major threats to global healthcare system and it is a major barrier to achieve herd immunity around the globe.

Pakistan has begun vaccinating its people in a systematic phase-wise manner under which the healthcare workers and elderly people are prioritized for vaccination.

Previous experience tells us that vaccine hesitancy is a major problem in Pakistan and it is better to understand perceptions of pharmacists about COVID-19 vaccine who are the primary source of information for most of general population.

What this study adds:

This study is first of its kind to explore vaccine hesitancy among Pakistani pharmacists and the results of this study show that majority of the participants were willing to get COVID-19 vaccine and few of them have even got themselves vaccinated at the start of vaccination campaign.

Many among the willing participants considered cost of vaccine, adverse reactions, limited data, safety, and efficacy as major hindrance to their decision to get vaccine.

Few participants were found highly vaccine-hesitant because of their staunch belief in the prevalent myths and rumors about COVID-19 vaccine.

55 Donor age has the least influence on recovery, quality, and in vitro developmental competence of ovum pickup–based Holstein Friesian oocytes under subtropical conditions

The use of oocytes obtained from younger donors for invitro fertilization followed by embryo transfer represents an opportunity to accelerate genetic gain by reducing generation interval. The present study was designed to evaluate the effect of age of donor on the follicular population, recovery, quality and invitro developmental competence of ovum pickup based Holstein Friesian oocytes under subtropical conditions. A total of eight (n=8) Holstein Friesian (with proper oestrus cyclicity) were selected for the study and divided into 2 groups based on animal age: (1) heifers (n=4), 1.5 to 2 years of age, and (2) adults (n=4), 5 to 6 years of age. The study was conducted near Lahore (31°33′ N, 74°19′ E), Punjab, Pakistan, from November 2019 to February 2020. The animals were wave synchronized using the physiological method of wave synchronization. After 4 days of second dominant follicle puncture, the first ovum pickup was carried out and a total of nine (n=9) OPU sessions were held for each group. The COCs from the follicles were aspirated using a transvaginal ultrasound–guided needle. Following searching and grading, COCs of grade A, B and C were processed for IVM in 100-µL droplets of BO-IVM under mineral oil at 37°C, 5% CO2, and 95% humidity for 24h. The frozen semen of a high-pedigree bull was thawed at 37°C and observed for post-thaw sperm motility. The semen samples of the same bull having motility >50% were processed using the sperm swim-up method throughout the study. The IVF was carried out by placing the COCs and required amount of sperm in 100-µL droplets of BO-IVF at similar conditions for a maximum of 18h. The presumptive zygotes were denuded by gentle pipetting and cultured for a period of 7 days after placing in 100-µL drops of BO-IVC at 37°C, 5% CO2, 5% O2, and maximum humidity. The presumptive zygotes were observed for cleavage rate and blastocyst rate on Days 2 and 7 following COCs-sperm co-incubation. Data on the follicular population, oocytes recovered, and viable oocytes were analysed by the PROC GLIMMIX of SAS (SAS Institute Inc.), and proportional data were analysed by the Chi-squared method using SAS 9.1. COCs of grade AB (35.2 vs. 25.4%) were higher (P>0.05) in the adult group than in the heifer group, respectively. Similarly, COCs with grade CD (57.5 vs. 71.9%) were lower (P<0.05) in the adult group compared with the heifer group, respectively. However, the total follicles (6.55±0.42 vs. 6.39±0.39), number of COCs recovered (3.33±0.32 vs. 3.17±0.41), viable oocytes (3.08±0.29 vs. 3.08±0.39), cleavage rate (60.3 vs. 68.7%), and blastocyst rate (38.7 vs. 48.8%) did not differ (P>0.05) between the groups. To conclude, donor age up to third lactation, under subtropical conditions, does not affect invitro embryo production in Holstein Friesian undergoing repeated OPU.

54 Effect of clinical endometritis on the follicle growth dynamics, oocyte recovery, oocyte quality, and invitro developmental competence of oocytes using ovum pickup in Sahiwal cattle

Sahiwal cattle is the premium quality milk breed of cattle in Pakistan. Uterine infections often lead to culling of valuable animals from a herd, resulting in genetic drain. The genetic potential of problematic females could be reaped by invitro embryo production. The objective of the present study was to evaluate the effect of clinical endometritis on follicle growth dynamics, recovery, quality, and invitro developmental competence of oocytes using ovum pickup (OPU) in Sahiwal cattle. The animals, 5–7 years of age, third or fourth parity, and 160 to 170 days in milk (DIM), were inspected for any discharge at the vulva or inside the vagina. Then, B-mode ultrasonography was performed to measure the diameter of cervix and to examine the uterus for the presence of pus. The animals (n=12) were divided into 2 groups: (1) healthy (n=6), and (2) clinical endometritis (n=6), based on the presence or absence of pus at the vulva or in the vagina. The first OPU was performed after 7 days of dominant follicle puncture and subsequently repeated OPUs (54 and 50), after every 7 days over 9 OPU sessions, were performed in the healthy group and clinical endometritis group, respectively. Follicles were aspirated using transvaginal ultrasound–guided needle. Viable COCs were considered for further processing only and were placed in the 100-µL droplets of BO-IVM medium and incubated at 37°C, 5% CO2, and 95% humidity for 24h. Nuclear maturation was estimated by staining the oocytes with Hoechst 33342. Frozen semen from the same Sahiwal bull was thawed and processed for IVF throughout the study. Sperm were prepared using swim-up protocol. Sperm and COCs were co-incubated in 100-µL droplets of BO-IVF for 18h. Finally, presumptive zygotes were cultured in 100-µL drops of BO-IVC medium at 37°C, 5% CO2, 5% O2, and 95% humidity for a period of 7 days. Cleavage rate and blastocyst rate were recorded on Day 2 and 7 following IVF, respectively. The data were analysed using the GLIMMIX procedure of SAS (SAS Institute Inc.). The results revealed that the number of medium-sized follicle (1.32±0.11 vs. 0.56±0.11) and total follicles (9.14±0.70 vs. 6.58±0.72) were higher (P<0.05) in the healthy group than in the clinical endometritis group, respectively. Similarly, the number of oocytes recovered (5.05±0.39 vs. 2.78±0.41), viable oocytes (2.87±0.25 vs. 1.46±0.26), COCs with grade AB, having minimum of 2 cumulus cell layers and homogeneous cytoplasm, (33 vs. 20%) and nuclear maturation (68 vs. 55%) were also higher (P<0.05) in the healthy group than in the clinical endometritis group, respectively. However, cleavage rate (55 vs. 46%) and blastocyst rate (29 vs. 26%) did not differ (P>0.05) between the groups. In conclusion, clinical endometritis has a negative effect on follicle growth dynamics, oocyte recovery, oocyte quality, and nuclear maturation; however, the developmental competence of COCs is not compromised by it.

Electron number density conservation model combined with a self-absorption correction methodology for analysis of nanostructure plasma using laser-induced breakdown spectroscopy

We studied laser ablation and plasma property evolution for a nickel (Ni) doped tin (Sn) oxide nanostructures target using laser-induced breakdown spectroscopy (LIBS). The transition metal Ni doped tin oxide nanostructures were synthesized by co-precipitation and hydrothermal methodologies. The size of prepared nanoparticles was verified by X-ray diffraction and transmission electron microscopy techniques. A frequency-doubled pulsed Nd:YAG laser with a wavelength of 532 nm was used to produce ablated plasma nanostructures. Ablation of doped and undoped nanostructures revealed salient-enhanced spectral emissions compared with their bulky counterparts. The emission lines of the constituent elements of doped material were used to find plasma parameters. The plasma temperature was estimated from a Boltzmann plot, and the electron number density was determined from the Saha-Boltzmann equation. The self-absorption effect has been observed in tiny plasma of nanostructures. The affected profiles of spectral lines of Ni and Sn nanoparticles due to self-absorption in LIBS spectra were corrected by the internal reference self-absorption correction (IRSAC) methodology. After correction of emitted line intensities by IRSAC, the electron number density (END) conservation approach was applied for quantitative analysis of doped nanostructures. In the END conservation approach, quantitative analysis of samples was carried out using electron number densities. Quantitative results derived from the END conservation approach at high and low concentrations exhibited good correlation when these were compared and validated with results from a conventional calibration free approach and the standard recognized energy dispersive X-ray technique.

Factors affecting outcome after the use of the Ponseti method for the management of idiopathic clubfoot, a retrospective study in an orthopaedic referral institute

TIn the last few decades Ponseti method has replaced soft tissue releases as the gold standard in the management of idiopathic clubfoot. However, the recurrence of the deformity is common without post tenotomy bracing. The purpose of this study was to retrospectively see various attributes of the patients associated with poor outcome after use of Ponseti method in idiopathic clubfoot management. Seventy nine consecutive patients with one hundred and twenty three idiopathic clubfeet treated with Ponseti method by single orthopaedic surgeon were followed for a period of two years and recurrence of the deformity was studied in relation to age of patient at presentation (< 3 months or more), sex of the patient, severity of the deformity ( moderate to severe verses (Vs.) very severe), compliance to post tenotomy bracing (compliant Vs. non compliant), educational level of parents (high school or less) and access of parents to internet (Yes or No) and odds ratio for recurrence and level of significance determined for each using Fisher's exact t-test. Non compliance in seventeen patients (17.7%) with post tenotomy bracing was the most important factor related to the recurrence, with an odds ratio of 6.22 (P =0.0059). Educational level (less than high school) of parents (36.7%) was the second most important factor with odds ratio of 5.5 (P=0.0073). Fifteen patients with severe Demiglio scoring feet had an odds ratio of 5.3 (P= 0.0097) for the recurrence of the deformity. Inaccess of the parents to the internet had an odds ratio of 6.33 (P =0.011) for the recurrence of the deformity. Age and sex of the patients was not found to have a significant effect on the recurrence of the deformity. In conclusion, the risk factors associated with recurrence of the idiopathic clubfoot deformity except severity of the deformity are modifiable and extra minutes can be spent with risk group parents during follow up visits to prevent a recurrence by making them understand natural history of the corrected foot without post tenotomy bracing, encouraging them for regular follow up visits, arranging interactive sessions with other patients who are regular in their follow up and compliant with bracing, and encouraging the literate parents to update their information about clubfoot from internet.

Hand amputations: epidemiology, management and resurfacing options for soft tissue coverage

OBJECTIVE

Agricultural hand injuries occur mainly among young adults, many affecting the dominant hand, thereby impeding patients' ability to work or cope with social obligations. This study was carried out with the aim of collecting data on the epidemiology and management of agricultural hand injuries in Indian subjects.

METHOD

The study was conducted in the Department of Plastic and Reconstructive Surgery, JN Medical College, AMU, Aligarh, India, from October 2009 to December 2013. Patients with agricultural hand injuries were included. Data collected included socio-demographic details, mode and type of injury, type of reconstruction, complications, length of hospital stay and assessment of post-reconstruction status. These data were tabulated and analysed.

RESULTS

The typical patient was young (mean 33.2 years), of lower socio-economic status and with a total disregard for safety regulations. There is clustering of cases during the wheat harvest season (April-June). Wheat thresher injuries were the most common cause of partial hand amputation (51%), especially during this season. This was followed by fodder cutting (kutti/chara) machine injury, especially in females and children (36%). A simple classification for these injuries has been described and Grade II injury was the commonest. Reverse radial forearm flap was the most suitable regional flap for coverage, whereas thoraco-umbilical flap was the most commonly used distant flap. Patients who had the single-stage procedure had a significantly shorter stay.

CONCLUSION

Agricultural hand injuries are not totally avoidable and their incidence can be reduced by proper education, but the low economic and literacy status of the patients is a big hurdle. The forearm offers many flaps for reconstruction of hand, which can be used in defects on dorsal or palmar aspect of hand and results in early discharge from the hospital and early rehabilitation. In patients with associated injury to the forearm, abdominal flaps can be used for cover.

Application of Heavy Metal Rich Tannery Sludge on Sustainable Growth, Yield and Metal Accumulation by Clarysage (Salvia sclarea L.)

A field experiment was conducted to evaluate the effective utilization of tannery sludge for cultivation of clarysage (Salvia sclarea) at CIMAP research farm, Lucknow, India during the year 2012-2013. Six doses (0, 20, 40, 60, 80, 100 tha(-1)) of processed tannery sludge were tested in randomised block design with four replications. Results revealed that maximum shoot, root, dry matter and oil yield were obtained with application of 80 tha(-1)of tannery sludge and these were 94, 113 and 61% higher respectively, over control. Accumulation of heavy metals (Cr, Ni, Fe, Pb) were relatively high in shoot portion of the plant than root. Among heavy metals, magnitude of chromium accumulation was higher than nickel, iron and lead in shoot as well as in root. Linalool, linalyl acetate and sclareol content in oil increased by 13,8 and 27% respectively over control, with tannery sludge application at 80 tha(-1). Heavy metals such as chromium, cadmium and lead content reduced in postharvest soil when compared to initial status. Results indicated that clarysage (Salvia sclarea) can be grown in soil amended with 80 tha(-1)sludge and this can be a suitable accumulator of heavy metals for phytoremediation of metal polluted soils.

Genotypic variability for root/shoot parameters under water stress in some advanced lines of cotton (Gossypium hirsutum L.)

Research pertaining to genetic variability parameters, heritability, and genotypic, phenotypic, simple, and environmental correlations for various seedling traits in five elite advanced cotton (Gossypium hirsutum L.) lines (FH-113, FH-114, FH-941, FH-942, and FH-2015) and one check (CIM-496) was carried out during October and November 2010 under greenhouse conditions at the Cotton Research Institute (Faisalabad, Pakistan). Material was raised in plastic tubes with a randomized complete block design replicated three times. Three drought shocks were applied by withholding water from the tube-sown plants for 8-, 10-, and 12-day intervals. After 60 days of sowing, data on root/shoot traits like root length (cm), shoot length (cm), root weight (g), shoot fresh weight (g), lateral root number, root dry weight (g) shoot dry weight (g), and total plant weight (g) were recorded. Considerable genotypic variations existed between genotypes for all seedling characters. Higher broad-sense heritability estimates were found for all traits studied. Maximum broad-sense heritability coupled with high genetic advance in root length (0.99, 17.34), lateral root number (0.91, 2.89), and shoot length (0.90, 4.35) suggested a potential for genetic improvement through breeding and selection. The correlation coefficients among root length, shoot length, root dry weight, fresh shoot weight, and total plant weight were positively and significantly correlated; thus, they can be selected simultaneously as drought tolerance selection indexes owing to the absence of undesired relationships. Genotypes FH-942 and FH-113 had the lowest excised leaf water loss during the first 4 h and also for the next 4 h. Therefore, these two advanced lines (FH-942 and FH-113) with high initial water content and lower excised leaf water loss had better adaptation to water stress.

Alar base resection - Medial flap technique

The primary goal of alar base resection is the narrowing of nasal base while preserving or recreating normal contour. The standard wedge resection, as proposed by Weir, does narrow the base but too open at the expense of normal appearing nostrils. 25 patients were taken up for corrective septo-rhinoplasty of which 5 patients needed alar base resection. The medial flap technique as proposed by Jack Sheen was adopted and normal appearing nasal base achieved in all cases.

Determinants influencing prevalence of louse infestations on layers of district Faisalabad (Pakistan)

1. This paper describes the influence of some epidemiological determinants on the prevalence of louse infestation on layers in Faisalabad (Pakistan). 2. Seventy layer farms were screened to determine the prevalence of louse infestation and its determinants including age of the bird, availability of space per bird and frequency of litter change. Prevalence of Lipeurus caponis was highest (53.2%), followed by Menacanthus stramineus (22.16%), Goniodes dissimilis (12.37%) and Goniodes gallinae (12.37%). 3. Older birds (36 to 74 weeks of age) were found with a significantly higher prevalence of louse infestation than younger birds. 4. Month-wise prevalence of louse infestation was higher during the summer months (from April to August) and at older age. 5. Birds kept at floor area allowances ranging from 0.43 to 0.55 m(2) were highly infested with lice as compared to those provided with a space of 0.61 m(2) or higher per bird. 6. Litter change frequency after every 8 weeks resulted in a reduced chance of louse infestation as compared to less frequent litter changing practice. 7. It was concluded from the study that the louse infestation is a menace for the poultry production industry in Pakistan and age, space per bird and litter change frequency are the influencing determinants. 8. Further research on the chemotherapeutic trials and resistance in poultry should be continued for an effective lice control program.

Peritoneal dialysis for adults with acute renal failure: an underutilized modality

In order to evaluate the effects of peritoneal dialysis as a modality of renal replacement therapy for adults with acute renal failure (ARF) of varied etiologies, we studied 43 ARF patients who underwent peritoneal dialysis at our hospital from April 2004 to November 2005. The age of the patients ranged from 18 to 75 years with a mean of 35 years. There was no significant difference in the incidence of ARF between males and females. Acute tubular necrosis secondary to acute gastroenteritis was the cause of ARF in 32 (80%) patients; four (10%) patients expired secondary to ARF. There was an average fall of around 60% in the S. creatinine at the end of PD. We did not notice any significant complications related to the procedure. We conclude that peritoneal dialysis is still a good option for the treatment of patients with ATN.

The structure of zwitterionic phosphocholine surfactant monolayers

The structure of a zwitterionic phosphocholine (PC) surfactant monolayer adsorbed on the surface of water has been determined using neutron reflectivity in combination with H/D isotopic substitution. The most significant results of this study are the level of hydration of the PC headgroup and the lack of dehydration with increasing temperature and salt addition. The fraction of the alkyl chain (f(c)) immersed in water for all three chain isomers studied was found to be around 0.15, suggesting that the PC headgroup geometries influenced not only the headgroup hydration but also the degree of immersion of the alkyl chain in water. At the critical micelle concentration (CMC), the number of water molecules associated with the PC headgroup in C(m)PC (m = 12, 14, 16) was on order of 15. This value was significantly greater than that obtained for nonionic and ionic surfactants with similar limiting area per molecule at the CMC (A(cmc)). However, the fraction of the chain immersed in water for the ionic and nonionic surfactants was much greater. This suggests that the unique surface biocompatibility of PC surfactants arises from their strong affinity for water, and the relatively low fraction of mixing with the alkyl chain arises from the higher structural order within the PC monolayer. As surface coverage decreased, the number of water molecules associated with each PC headgroup increased, but f(c) remained constant for all the surfactants. This observation was consistent with the small variation in the thickness of the headgroup region, and the entire layer changed little with surfactant concentration. This is attributed to the role of PC headgroup geometries to maintain the conformational order within the layer as packing density varies. Further structural analysis based on a kinematic approach showed that, as the chain length was increased from C12 to C14 to C16 at the CMC, the angle of tilt for the alkyl chain increased from 40 degrees to 48 degrees to 53 degrees , respectively, whereas the thickness of the whole layer and that of the PC head region was largely constant. The almost vertical projection of the PC headgroup from these single alkyl chain surfactants is in sharp contrast to its strongly tilted conformation, as reported for dichain phospholipids such as dipalmitoyl glycerol phosphocholine (DPPC).

Neutron reflection from the liquid-liquid interface: adsorption of hexadecylphosphorylcholine to the hexadecane-aqueous solution interface

Adsorption of water-soluble, zwitterionic n-hexadecylphosphorylcholine (C(16)PC) amphiphiles has been examined at the hexadecane-aqueous solution interface using neutron reflectivity (NR) and interfacial tension measurements. The results of both methods indicate that the limiting area per surfactant molecule at the interface at the critical micelle concentration (cmc) is 40 +/- 5 Angstroms(2). In the NR measurements, two isotopic contrasts have been employed to determine the adsorption isotherm and to explore the structure of the interfacial region. Single-layer model fitting to both isotopic contrasts was only possible for the single sub-cmc concentration studied, where a film thickness of 60 +/- 5 Angstroms was obtained; consistent single-layer model fits to both contrasts for concentrations greater than the cmc were not possible, leading to the requirement of a two-layer model with an overall film thickness close to 60 +/- 2 Angstroms. This film thickness is appreciably greater than the fully extended C(16)PC molecular length and cannot be explained purely in terms of thermal broadening. A further result is that the reflectivity data indicate that, as the C(16)PC concentration increases, the amount of water on the hexadecane side of the interfacial region increases, in contrast to intuitive expectation. These findings are interpreted by conjecturing a structural model in which a trilayer of C(16)PC molecules is formed at the interface with the water concentrated in the region occupied by the headgroups.

Adsorption of single chain Zwitterionic phosphocholine surfactants: Effects of length of alkyl chain and head group linker

The adsorption of a range of single chain zwitterionic phosphocholine surfactants (C(n)P(m)C) at the air/liquid interface has been studied by a combination of surface tension and neutron reflectivity. The critical micellar concentration (CMC) for C(n)PC (or C(n)P(2)C), where n varied from 12, 14 to 16, was found to be 0.91, 0.14, and 1.2 x 10(-2) mM respectively, and followed the same trend as observed for other zwitterionic and non-ionic surfactants. The area per molecule at the CMC, A(cmc), for C(n)PC was found to remain constant between 50 and 53 A(2), indicating that the increase in the alkyl chain length had little effect on A(cmc) at the interface. The neutron reflection measurement also showed an almost constant layer thickness (tau) of 20+/-2 A from all the alkyl chain deuterated PC surfactants (dC(n)hPC) in null reflecting water (NRW), suggesting that the alkyl chains of the surfactant responded to changes in either chain length or solution concentration by varying their angle of tilt. In contrast, increasing the length of head group linker between P and N atoms in C(12)P(m)C, where m=2, 4, to 6, resulted in a much slower decrease of CMC from 0.91, 0.7, to 0.5 mM, consistent with a different contribution to the free energy of micellization. A(cmc) for C(12)P(m)C did not vary when m was increased from 2 to 4, and this observation together with the thickness of the head group region indicated an almost perpendicular projection of the head group in C(12)P(2)C and C(12)P(4)C. A further increase in m to 6 resulted in an A(cmc) of 70 A(2). This increase in A(cmc) however did not result in any change in either the total layer thickness or the fraction of the head group region submerged in the aqueous subphase, suggesting that the head group in C(12)P(6)C was bent away from the surface normal direction. Both increase in temperature from 25 to 40 degrees C and the addition of 0.1 M NaCl had little effect on the area per molecule or the thickness of C(12)P(m)C surfactant layer, showing that the C(12)P(m)C series behaved like C(n)P(2)C series. The main conclusion from this study is that for all the C(n)P(m)C surfactants studied, change in m or n has little effect on the total thickness, the thickness of the alkyl chain or that of the head group region.

Surface adsorption of zwitterionic surfactants: n-alkyl phosphocholines characterised by surface tensiometry and neutron reflection

The surface adsorption of n-dodecyl phosphocholine (C12PC) has been characterised by a combined measurement of surface tension and neutron reflectivity. The critical micellar concentration (CMC) was found to be 0.91 mM at 25 degrees C in pure water. At the CMC, the limiting area per molecule (A(cmc)) was found to be 52+/-3 A2 and the surface tension (gamma(cmc)) to be ca. 40.0+/-0.5 mN/m. The parallel study of chain isomer n-hexadecyl phosphocholine (C16PC) showed a decrease of the CMC to 0.012 mM and a drop of gamma(cmc) to 38.1+/-0.5 mN/m. However, A(cmc) for C16PC was found to be 54+/-3 A2, showing that increase in alkyl chain length by four methylene groups has little effect on A(cmc). The almost constant A(cmc) suggested that the limiting area per molecule was determined by the bulky PC head group. It was further found that the surface tension and related key physical parameters did not vary much with temperature, salt addition, solution pH or any combination of these, thus showing that surface adsorption and solution aggregation from PC surfactants is largely similar to the zwitterionic betaine surfactants and is distinctly different from ionic and non-ionic surfactants. The thickness of the adsorbed monolayers measured from both dC12hPC and dC16hPC was found to be 20-22 A at the CMC from neutron reflectivity. Neither A(cmc) nor layer thickness varied with alkyl chain length, indicating that as the alkyl chain length became longer it was further tilted away from the surface normal direction and the layer packing density increased. It was also observed that the thickness of the layer varied little with surfactant concentration, indicating that the average conformational orientation of the alkyl chain remained unchanged against varying surface coverage.

Cockayne syndrome

We report four cases of Cockayne Syndrome in a family of seven children. Apart from the usual clinical and laboratory features, sparse eye lashes and high arched palate in two patients, conjunctival and corneal edema in one, and proximal muscle weakness in one patient were noticed as additional findings.

Nonendoscopic removal of percutaneous endoscopic gastrostomy tubes: morbidity and mortality in children

BACKGROUND

Percutaneous endoscopic gastrostomy (PEG) tubes are often removed by cutting the tubing at skin level and allowing the internal components to pass through the gastrointestinal tract. This technique is commonly used in adults, but little information is available concerning its safety in younger patients.

METHODS

To assess the safety of this approach in children, the clinical courses of all patients who had undergone PEG tube removal in our pediatric gastroenterology unit over a 3-year period were reviewed.

RESULTS

Five of 11 patients in whom the internal components were allowed to pass developed significant complications. Three required subsequent endoscopic removal of the internal component due to persistent vomiting, one died from complications of esophageal perforation caused by the retained internal component, and one developed a gastrocutaneous fistula containing the retained bumper 2 years after PEG tube removal. Significant complications occurred more often in the younger and smaller patients.

CONCLUSIONS

Small children are at greater risk than adults for developing serious complications associated with unremoved PEG tube internal components. If passage of the internal components cannot be confirmed after 2 weeks, chest and abdominal radiographs should be obtained.

Seroprevalence of antibodies to Toxoplasma gondii, with particular reference to obstetric history of patients in Rawalpindi-Islamabad, Pakistan

Six hundred and forty blood samples were obtained from Rawalpindi-Islamabad to determine the frequency of Toxoplasma gondii antibodies using indirect immunofluorescent antibody (IFA) test. Two hundred and forty samples were from suspected cases of Toxoplasmosis. Forty (17%) cases were positive for IgG antibody. Seven (3%) of these cases showed antibody titre greater than 1:320. Of 65 children tested, 8 (12.30%) were positive. Four (6%) children had a rising titre from 1:160 to 1:1025. Prevalence of Toxoplasma antibodies was correlated to mode of living, maternal obstetric history, their animal contact and age of the children.