Knowledge, Attitude and Practice of Undergraduate Medical Students of Bangladesh Regarding COVID-19 and its Vaccination

Medical students are one of the socially active, reliable, and persuading population of information, prevention and control, and incentive of vaccination to stop the current pandemic situation. Consequently, knowing the status of medical students' knowledge, about symptoms, and transmission of disease, prevention of COVID-19 and their attitudes towards a vaccine is important. This multi-center cross-sectional descriptive study was one of the first ones in Bangladesh among the undergraduate medical students who completed pathology, microbiology, and pharmacology. The study was conducted from March to April 2021, using a convenience sampling method in twelve government and non-government medical colleges. Among 1132 who completed the questionnaire, and 15 students from different centers were excluded from the pre-testing and face validation. The age of the 1117 respondents were 22 to 23 years, of which the majority of the respondents were female 749 (67.0%), and 368 (33.0%) were male. Almost all participants had correct knowledge (84.1%) about the symptoms of COVID-19. But 59.2% had wrong knowledge about transmission of disease by an afebrile person. Above 60.0 % of the participants have worn a facial mask when contacting people, refrained from shaking hands, washed hands, avoided people with signs and symptoms suggestive of COVID-19, and avoided crowded places as a practice of prevention. 37.6% of medical students showed positive attitudes about the participation of management of a COVID-19 patient. Most of the participants' decided to have a vaccine depending on its availability. But 31.5% had trust in natural immunity rather than vaccination. Most undergraduate Medical college students understood the basic information, possessed a positive attitude, and presented good practice towards the COVID-19 and vaccination. They play a crucial role in motivation and acceptance of vaccines among the general citizen to fight back against the pandemic in the country with limited resources.

Physical, Psychological and Social Impact of COVID-19 Pandemic on Healthcare Workers at a COVID Designated Bangladeshi Public Hospital

The world has been devastated facing the outbreak of a novel infectious disease known as Corona virus disease (COVID-19). This has been declared as a pandemic by the World Health Organization. The frontline health care workers, who are directly involved in the diagnosis, treatment and care of patients with COVID-19, are taking significant personal risks on their own health and those of their family members. Objectives of the study include establishing the physical, psychological and social impact experience by the healthcare workers serving in public hospitals of Bangladesh. This prospective cross-sectional observational study was carried out at Kuwait Bangladesh Friendship Government Hospital, the first Covid-19 designated hospital of Bangladesh between the 1st June and the 31st August, 2020. A total of 294 doctors, nurses, ward boys and ailed healthcare workers were included in this study via purposive sampling. The study found statistically significant (p value 0.024) difference of medical co-morbidities between Covid-19 positive and Covid-19 negative groups of health care professionals. Significant association was found between duration of work and presence during aerosol generating procedure with COVID infectivity of the study subjects. 72.8% respondents experienced public fear of contracting the virus from them and 69.0% noticed negative attitude of the society towards them. Eighty five percent (85.0%) did not get any community support during this pandemic crisis. The health care professionals engaged in COVID-19 treatment have been taking significant personal risk on their life in terms of physical, psychological and social perspective. Providing safeguard to the health care workers are integral components of public health measures for addressing the COVID-19 pandemic. Special interventions to promote their physical wellbeing and arrangement of adequate psychological training need to be immediately implemented to cope up this critical situation.

Bioactivity evaluation and HPLC UV-VIS based quantification of antioxidant secondary metabolites from extract and fractions of Bistorta amplexicaulis rhizome

Bistorta amplexicaulis is a popular medicinal plant and reported as rich source of antioxidant compounds. The present study was designed for antioxidant and anticancer potential of polarity based fractions of B. amplexicaulis and its correlation to the secondary metabolites quantified by HPLC-UV/VIS.Crude extract was prepared by maceration method and polarity based fractions were prepared by solvent-solvent extraction. Antioxidant and anticancer potential was investigated by using various physiological and non-physiological assays while secondary metabolites rutin, naringin and quercetin present in extract and fractions were quantified by using HPLC- UV/VIS. All extracts showed Antioxidant potential but highest activity was obtained with ethyl acetate fraction (DPPH IC50 5.76±0.03 µg/ml, ABTS IC50 0.74±0.1 µg/ml, Total Antioxidant Assay 72.55±0.098 Ascorbic acid equivalents, Super oxide radical scavenging assay IC506.86±0.1909 µg/ml, Hydroxyl radical scavenging assay IC50 0.96±0.1690 µg/ml). The cytotoxicity of fractions against HepG2 cell lines showed lowest ell viability in n-hexane fraction (11%). The results revealed that ethyl acetate fraction of B. amplexicaulis can be a potential source of novel antioxidant compounds while n hexane fraction could provide anticancer compounds. A new method of simultaneous quantification of three flavonoids by using UV/VIS detector is reported in this study.

Bioactivity evaluation and HPLC UV-VIS based quantification of antioxidant secondary metabolites from extract and fractions of Bistorta amplexicaulis rhizome

Bistorta amplexicaulis is a popular medicinal plant and reported as rich source of antioxidant compounds. The present study was designed for antioxidant and anticancer potential of polarity based fractions of B. amplexicaulis and its correlation to the secondary metabolites quantified by HPLC-UV/VIS.Crude extract was prepared by maceration method and polarity based fractions were prepared by solvent-solvent extraction. Antioxidant and anticancer potential was investigated by using various physiological and non-physiological assays while secondary metabolites rutin, naringin and quercetin present in extract and fractions were quantified by using HPLC- UV/VIS. All extracts showed Antioxidant potential but highest activity was obtained with ethyl acetate fraction (DPPH IC50 5.76±0.03 µg/ml, ABTS IC50 0.74±0.1 µg/ml, Total Antioxidant Assay 72.55±0.098 Ascorbic acid equivalents, Super oxide radical scavenging assay IC506.86±0.1909 µg/ml, Hydroxyl radical scavenging assay IC50 0.96±0.1690 µg/ml). The cytotoxicity of fractions against HepG2 cell lines showed lowest ell viability in n-hexane fraction (11%). The results revealed that ethyl acetate fraction of B. amplexicaulis can be a potential source of novel antioxidant compounds while n hexane fraction could provide anticancer compounds. A new method of simultaneous quantification of three flavonoids by using UV/VIS detector is reported in this study.

Effectiveness of fascial closure technique following percutaneous endovascular aneurysm repair

INTRODUCTION

Percutaneous access and closure is commonly performed for patients undergoing endovascular aneurysm repair (EVAR). It has proven to be a safe and successful method of closure associated with fewer complications when compared with the traditional open technique. Fascial closure is an alternative technique that can be used for closure reducing the risks associated with the open technique. The aim of this study was to assess the safety and durability of fascial closure for failed percutaneous closure device following EVAR.

MATERIALS AND METHODS

Over a 12-month period, 49 patients who had undergone EVAR were identified via our EVAR register. Retrospective analysis of the clinical records was undertaken. We identified all the patients who had fascial closure of the groins following a failed percutaneous closure device. Patients had a computed tomography angiogram one month postoperatively, with duplex imaging and clinic follow-up three months later.

RESULTS

Fascial closure was performed in 14 groins. It failed in three groins and these patients had traditional open repair. Fascial closure was successful in 11 groins (7 patients). Of these seven patients, one was female (6%). The mean age was 80 years (range 68-92 years). Two patients died and one was lost to follow-up. One pseudoaneurysms were seen on computed tomography angiogram, which was managed conservatively and had resolved on follow-up imaging.

CONCLUSIONS

Fascial closure is a very good alternative to open repair after failure of the closure device.

Prolonged Mechanical Circumferential Stretch Induces Metabolic Changes in Rat Inferior Vena Cava

OBJECTIVE/BACKGROUND

Circumferential stretch on the vein wall has been suggested as a potential etiological factor in the development of varicose veins. However, the influence of vein wall stretch on vein metabolism has not yet been explored. The aim of this study was to investigate the effect of short and prolonged mechanical stretch on vein wall metabolism.

METHODS

Circular segments of inferior vena cava from male Sprague-Dawley rats were exposed to normal 0.5-g (nonstretched) or high 2-g (stretched) tension for short (4 h) or prolonged (18 h) duration (five vein segments per group). Contraction response to phenylephrine (10^-5 M) and KCl (96 mM) was elicited to observe the effect of circumferential stretch on vein function. The polar and organic metabolites in vein tissue were extracted using a bilayer extraction method. Aqueous and organic extracts were analyzed using nuclear magnetic resonance spectroscopy and ultra performance liquid chromatography coupled to mass spectrometry, respectively. Data acquired from both analytical platforms were analyzed using mathematical modeling.

RESULTS

Increased concentrations of valine (p = .02) and choline (p = .03) metabolites and triglyceride moieties (p = .03) were observed in veins stretched for 18 h compared with the nonstretched/18 h group.

DISCUSSION

Increased concentrations of branched chain amino acid valine and cell membrane constituent choline indicate increased muscle breakdown and increased metabolism of membrane phospholipids under stretch in an ex-vivo model. Increased intensities of triglyceride moieties in stretched vein segments for 18 h suggest that high pressure may induce an inflammatory response.

CONCLUSION

This study has shown that prolonged mechanical circumferential stretch (18 h) alters the metabolic profile of rat inferior vena cava.

Fatal human eosinophilic meningo-encephalitis caused by CNS co-infection with Halicephalobus gingivalis and West Nile virus

The saprophytic nematode Halicephalobus is a rare cause of fatal human meningo-encephalitis, and West Nile virus is neurotropic flavivirus implicated in a variety of clinical neurologic syndromes. Here we report a case of rapidly progressive CNS encephalopathy and death. Serologic, immuno-histochemical, histopathologic and nucleic acid studies demonstrate the presence of active Halicephalobus and West Nile virus in the CNS tissue. This is the first reported case of co-infection with these neurotropic pathogens.

PAH exposure and oxidative stress indicators of human cohorts exposed to traffic pollution in Lahore city (Pakistan)

Pollution from road traffic is not only a major source of exposure to polycyclic aromatic hydrocarbons (PAHs) but also a growing problem in the city of Lahore (Pakistan). In this study, we evaluated exposure to traffic-related PAHs, among subjects including traffic police officers (TPs), rickshaw drivers (RKs) shopkeepers working near main roads (SKs) and a control group (CN) for comparative analyses. We monitored the 1-hydroxypyrene (1-OHP) as biomarkers of exposure to PAHs and its probable association with catalase (CAT), glutathione (GSH) glutathione peroxidase (GSHPx) activity as biomarkers of oxidative stress in selected cohorts from the city Lahore. Results showed that median 1-OHP concentration was significantly higher in TPs than CN (med 1.21 vs. 0.51 μmol mol-C(-1) respectively, P=0.046), followed by RKs (0.68 μmol mol-C(-1), P=0.19 vs. CN). Furthermore, GSH, GSHPx, and CAT activities were also higher in exposed subjects than CN, which indicated that they experienced oxidative stress. Similar, but less severe observations were recorded in SKs. Observation of self-reported health status showed that, on the basis of daily time spent in the middle of heavy traffic, TPs and RKs most frequently suffered from adverse head and respiratory symptoms. The study shows that increasing traffic pollution can be associated with important health risk factor not only for the workers in transport industry but also for the public. Finally, the issue of traffic pollution in Lahore city needs to be addressed on priority.

Vasoconstrictor and vasodilator responses to tryptamine of rat-isolated perfused mesentery: comparison with tyramine and β-phenylethylamine

BACKGROUND AND PURPOSE

Tryptamine increases blood pressure by vasoconstriction, but little is known about its actions on the mesentery, in particular the resistance arteries. Tryptamine interacts with trace amine-associated receptors (TAARs) and because of its structural similarity to 5-HT, it may also interact with 5-HT receptors. Our hypothesis is therefore that the rat mesenteric arterial bed will exhibit vasopressor and vasodepressor responses to tryptamine via both 5-HT and TAARs.

EXPERIMENTAL APPROACH

Tryptamine-evoked responses were assayed from pressure changes of the rat-isolated mesenteric vasculature perfused at constant flow rate in the absence and presence of adrenoceptor and 5-HT receptor antagonists.

KEY RESULTS

Tryptamine caused dose-dependent vasoconstriction of the mesenteric arterial bed as increases in perfusion pressure. These were unaffected by the α₁-adrenoceptor antagonist, prazosin, but were attenuated by the non-selective α-adrenoceptor antagonist, phentolamine. The 5-HT_2A receptor antagonists, ketanserin and ritanserin, abolished the tryptamine-induced pressure increases to reveal vasodilator responses in mesenteric beds preconstricted with phenylephrine. These tryptamine-induced vasodilator responses were unaffected by the 5-HT₇ receptor antagonist, SB269970, but were eliminated by the NOS inhibitor, N_ω-nitro-L-arginine methyl ester (L-NAME). Tyramine and β-phenylethylamine also caused vasodilatation in pre-constricted vasculature, which was also abolished by L-NAME.

CONCLUSIONS AND IMPLICATIONS

Tryptamine causes vasoconstriction of the mesenteric vasculature via 5-HT_2A receptors, which when inhibited exposed vasorelaxant effects in pre-constricted tissues. The vasodilatation was independent of 5-HT_2A and 5-HT₇ receptors but like that for tyramine and β-phenylethylamine was due to NO release. Potency orders suggest TAAR involvement in the vasodilatation by these trace amines.

Complications of Radiofrequency Ablation of Varicose Veins

Radiofrequency ablation (RFA) has become a valued weapon in the phlebologist's armoury. It offers ease of use and reproducibility with good outcomes. However, as with all interventions, complications arise. In this review we examine the complications inherent with RFA and their relative risk, with their avoidance measures if available. Overall, we find that RFA offers a very safe procedure with rare severe complications.

Gallstone ileus: a difficult emergency diagnosis!

Gallstone ileus (GSI) is a rare cause of mechanical small bowel obstruction. It occurs when a fistula between the gallbladder and the small bowel facilitates the migration of gallstone(s) into the small bowel. The commonest site of impaction is in the terminal ileum. We report the case of a 71-year-old female presenting with GSI diagnosed on CT scan. She was surgically explored and gallstones extracted by a simple enterotomy leading to full recovery of the patient.

Glucose oxidase immobilization on a novel cellulose acetate–polymethylmethacrylate membrane

Glucose oxidase (GOD) was immobilized on cellulose acetate-polymethylmethacrylate (CA-PMMA) membrane. The immobilized GOD showed better performance as compared to the free enzyme in terms of thermal stability retaining 46% of the original activity at 70 degrees C where the original activity corresponded to that obtained at 20 degrees C. FT-IR and SEM were employed to study the membrane morphology and structure after treatment at 70 degrees C. The pH profile of the immobilized and the free enzyme was found to be similar. A 2.4-fold increase in Km value was observed after immobilization whereas Vmax value was lower for the immobilized GOD. Immobilized glucose oxidase showed improved operational stability by maintaining 33% of the initial activity after 35 cycles of repeated use and was found to retain 94% of activity after 1 month storage period. Improved resistance against urea denaturation was achieved and the immobilized glucose oxidase retained 50% of the activity without urea in the presence of 5M urea whereas free enzyme retained only 8% activity.

Electrochemical approach of anticancer drugs--DNA interaction

The interaction of drugs with DNA is among the most important aspects of biological studies in drug discovery and pharmaceutical development processes. In recent years there has been a growing interest in the electrochemical investigation of interaction between anticancer drugs and DNA. Observing the pre and post electrochemical signals of DNA or drug interaction provides good evidence for the interaction mechanism to be elucidated. Also this interaction could be used for the quantification of these drugs and for the determination of new drugs targeting DNA. Electrochemical approach can provide new insight into rational drug design and would lead to further understanding of the interaction mechanism between anticancer drugs and DNA.

Intestinal Protozoa in Wild Boars (Sus scrofa) in Western Iran

A total of 12 gastrointestinal tracts of wild boars (Sus scrofa) from western Iran (Luristan) were examined for protozoan infection between September 2000 and November 2001. Of 12 boars examined, 67% harbored one or more species of the following protozoa: Balantidium coli (25%), Tritrichomonas suis (25%), Blastocystis sp. (25%), Entamoeba polecki (17%), Entamoeba suis (8%), Iodamoeba butschlii (17%), and Chilomastix mesnili (8%). Four of these protozoan species also are reported in humans, and persons living in rural areas where wild boars are abundant should take precaution to avoid infection.

Coccidiosis in the European badger, Meles meles in Wytham Woods: infection and consequences for growth and survival

In total 1502 faecal samples were collected from a population of European badgers (Meles meles) between 1992 and 1995 at Wytham Woods, Oxfordshire, UK. Two coccidia species, Eimeria melis and Isospora melis, were identified. Cubs showed a marked seasonal pattern of infection with E. melis, with infection occurring at significantly higher intensity and prevalence than in adults. There was preliminary evidence to suggest that infantile coccidiosis in badgers may be associated with impaired growth and increased mortality.

Developmental changes in reactivity of small femoral arteries in the fetal and postnatal baboon

OBJECTIVE

We evaluated in vitro responsiveness of small arteries (internal diameter, 300 microm) from the femoral vascular bed of normal fetal (0.75-1.0 gestation) and neonatal (43-46 days) baboons to investigate whether the transition from fetal to neonatal life was associated with functional alterations in vasoconstrictor and vasodilator responses.

STUDY DESIGN

The maximum response and sensitivity to potassium and to the constrictor agonists norepinephrine and U46619 (a thromboxane mimetic) were studied by in vitro myography. Vasodilator responses to the endothelium-dependent dilators acetylcholine and bradykinin were also investigated.

RESULTS

The maximum response to norepinephrine and U46619 and to potassium increased with gestational age, whereas the sensitivity to these vasoconstrictors was similar in all groups studied. In contrast, acetylcholine- and bradykinin-induced relaxation (median effective concentration and maximum response) did not change with age.

CONCLUSION

Receptor-mediated responses to a catecholamine, a prostanoid, and 2 endotheliumdependent vasodilators are similar in the fetal and neonatal baboon. The increase in maximal constriction with development, which is probably associated with growth or maturation of vascular smooth muscle, is likely to be a functionally important aspect in the development of cardiovascular function.

Non-linear changes of electrocortical activity after antenatal betamethasone treatment in fetal sheep

We determined the effects of betamethasone on the fetal sheep electrocorticogram (ECoG) using linear (power spectral) and non-linear analysis. For non-linear analysis we used an algorithm based on the Wolf algorithm for the estimation of the leading Lyapunov exponent which calculates a prediction error based on the course of the time series in the phase space. A high prediction error stands for low predictibility or low regularity and vice versa. After 48 h of baseline recordings, vehicle (n = 6) or betamethasone (n = 7) at 10 microg h(-1) was infused over 48 h to the sheep fetus at 128 days gestational age (0.87 of gestation). ECoG spectral analysis revealed no difference in power spectrum between vehicle- and betamethasone-treated fetuses. The prediction error of the ECoG during REM sleep was higher than during non-REM or quiet sleep in both groups (P < 0.0001) revealing lower causality of brain activity during REM sleep. During REM sleep, prediction error significantly decreased 18-24 h after onset of betamethasone treatment (P < 0.05) and returned to baseline values within the following 24 h of continued betamethasone treatment. No ECoG changes were found during quiet sleep. Non-linear ECoG changes during metabolically active REM sleep accompanied the previously described decrease in cerebral blood flow. These results suggest that betamethasone in doses used in perinatal medicine acutely alters complex neuronal activity.

Effects of betamethasone administration to the fetal sheep in late gestation on fetal cerebral blood flow

Glucocorticoid administration to women at risk of preterm delivery to accelerate fetal lung maturation has become standard practice. Antenatal glucocorticoids decrease the incidence of intraventricular haemorrhage as well as accelerating fetal lung maturation. Little is known regarding side effects on fetal cerebral function. Cortisol and synthetic glucocorticoids such as betamethasone increase fetal blood pressure and femoral vascular resistance in sheep. We determined the effects of antenatal glucocorticoid administration on cerebral blood flow (CBF) in fetal sheep. Vehicle (n = 8) or betamethasone (n = 8) was infused over 48 h via the jugular vein of chronically instrumented fetal sheep at 128 days gestation (term 146 days). The betamethasone infusion rate was that previously shown to produce fetal plasma betamethasone concentrations similar to human umbilical vein concentrations during antenatal glucocorticoid therapy. Regional CBF was measured in 10 brain regions, using coloured microspheres, before and 24 and 48 h after onset of treatment, and during hypercapnic challenges performed before and 48 h after onset of betamethasone exposure. Betamethasone exposure decreased CBF in all brain regions measured except the hippocampus after 24 h of infusion (P < 0.05). The CBF decrease was most pronounced in the thalamus and hindbrain (45-50% decrease) and least pronounced in the cortical regions (35-40% decrease). It was mediated by an increase in cerebral vascular resistance (CVR, P < 0.05) and led to a decrease in oxygen delivery to subcortical and hindbrain structures of 30-40%, to 8.6 +/- 1.1 ml x (100 g)(-1) x min(-1), and 40-45 %, to 11.0 +/- 1.6 ml x 100 g(-1) x min(-1), respectively (P < 0.05). After 48 h of betamethasone treatment, the reduction in CBF was diminished to about 25-30 %, but was still significant in comparison to vehicle-treated fetuses in all brain regions except three of the five measured cortical regions (P < 0.05). CVR and oxygen delivery were unchanged in comparison to values at 24 h of treatment. The CBF increase in response to hypercapnia was diminished (P < 0.05). These observations demonstrate for the first time that glucocorticoids exert major vasoconstrictor effects on fetal CBF. This mechanism may protect the fetus against intraventricular haemorrhage both at rest and when the fetus is challenged. Betamethasone exposure decreased the hypercapnia-induced increase in CBF (P < 0.05) due to decreased cerebral vasodilatation (P < 0.05).

Coccidiosis in the European badger (Meles meles) from England, an epidemiological study

In total 445 faecal samples were collected from 259 European badgers (Meles meles) in Wytham Woods, Oxfordshire, UK (462080). Microscopical examination revealed infection with 2 species of coccidia Eimeria melis and Isospora melis. From the initial examination of each animal, point prevalence rates of 0.44 and 0.35 were calculated for Eimeria and Isospora respectively. The intensity of infection was significantly greater for Eimeria than Isopora and the distribution of intensities was highly skewed for both species, with a few individuals shedding the majority of oocysts. Incidence and recovery rates for both coccidia species were calculated from longitudinal data collected at 3-monthly intervals from a subset of the adult badger population, and the predicted prevalence rates based on these were similar to the point prevalence rates. This suggests little, if any, parasite-induced mortality in the adult population. In contrast, there was a marked and significant reduction in the point prevalence and intensity of infection with Eimeria from cub to adult badger suggesting a degree of acquired immunity to Eimeria melis on initial exposure and/or that there is significant Eimeria-associated mortality in the cub population. No such relationship was found for Isospora infection. In those adult badgers with co-infections there was a direct relationship between the intensity of Eimeria and Isospora. The taxonomic status of these parasites suggests a heteroxenous life-cycle for I. melis, and direct transmission of E. melis. However, the greater than expected prevalence of co-infection is consistent with a common source of infection, such as communal latrines.

A comparative study of vascular responsiveness of myometrial and omental small resistance arteries in late-gestation sheep

OBJECTIVE

We determined whether local regulation by vasoactive agents differs in the myometrial and omental vascular beds in the pregnant sheep. Specifically, we hypothesized that there would be blunting of in vitro responses to constrictor agonists, enhancement of sensitivity to dilator agonists, or both in myometrial compared with omental resistance arteries.

STUDY DESIGN

We compared in vitro responsiveness of small resistance intramyometrial and omental arteries from near-term pregnant ewes to the vasoconstrictor agents norepinephrine, U46619 (a thromboxane sympathomimetic), and potassium and the vasodilator agents acetylcholine and bradykinin.

RESULTS

The vascular sensitivity and the maximum response of intramyometrial small arteries to U46619 was attenuated compared with that of omental arteries. There were no significant differences between the intramyometrial and omental arteries in response to norepinephrine, potassium, acetylcholine, or bradykinin.

CONCLUSIONS

These results support regional heterogeneity of regulation of function in different maternal vascular beds during pregnancy. The relative insensitivity of the myometrial arteries to the thromboxane mimetic indicates the existence of decreased constrictor function that may facilitate preservation of uterine blood flow in vivo.

Betamethasone-mediated vascular dysfunction and changes in hematological profile in the ovine fetus

Glucocorticoid administration to fetal sheep induces a sustained systemic blood pressure rise and an associated increase in femoral vascular resistance. We utilized a small vessel myograph to compare isometric vascular responses of small femoral arterial branches from fetal sheep infused intravenously with either betamethasone or vehicle in vivo from 128 days gestation. Changes in hematological parameters were also determined. Betamethasone was infused for 48 h to produce fetal plasma betamethasone concentrations similar to those observed in human fetuses after maternal treatment with betamethasone to accelerate fetal lung maturation. When compared with vessels removed from vehicle-infused fetuses, vessels obtained from betamethasone-treated fetuses exhibited 1) enhanced sensitivity to depolarizing potassium solutions; 2) no differences in response to the thromboxane mimetic U-46619 or norepinephrine; and 3) differential responses to vasodilators, enhanced sensitivity to ACh, but decreased response to bradykinin and forskolin. In addition, erythrocyte and leukocyte counts were increased in betamethasone-infused fetuses. These observations indicate that multiple mechanisms operate to increase fetal vascular resistance during antenatal betamethasone exposure.

Enhanced acetylcholine induced relaxation in small mesenteric arteries from pregnant rats: an important role for endothelium-derived hyperpolarizing factor (EDHF)

1. Small mesenteric arteries from pregnant rats demonstrated greater sensitivity (pEC50 : P<0.001) and maximum relaxation (P<0.01) to acetylcholine (ACh) than those of control non-pregnant animals. 2. Maximum relaxation, but not sensitivity, to ACh remained greater (P<0.01) in pregnant animals when evaluated in 25 mM KCl, which prevents relaxation dependent upon hyperpolarization. ACh induced relaxation in the presence of 25 mM KCl was completely inhibited in pregnant and non-pregnant groups by N(omega)-nitro L-arginine methyl ester (L-NAME, 100 microM), indomethacin (INDO, 10 microM) and oxadiazole quinoxalin (ODQ, 1 microM), suggesting pregnancy associated enhancement of dilator prostanoid and/or nitric oxide (NO) synthesis. 3. ACh induced relaxation in 5 mM KCI was only partially inhibited by a combination of N(omega)-nitro L-arginine methyl ester (L-NAME, 100 microM), indomethacin (INDO, 10 microM) and oxadiazole quinoxalin (ODQ, 1 microM). The residual relaxation, which was greater in arteries from pregnant rats (maximum relaxation: P<0.01), was prevented by 25 mM KCl, indicating pregnancy associated enhanced synthesis/ reduced degradation of a hyperpolarizing factor. Residual relaxation to ACh in 5 mM KCl was inhibited by the cytochrome P450 inhibitor, proadifen (1 microM) in the pregnant group (P<0.001). 4. Relaxation to spermine NONOate was similar in pregnant and non-pregnant groups and totally inhibited by ODQ (in the presence of L-NAME). 5. This study suggests that, in addition to enhanced endothelium dependent NO/dilator prostanoid synthesis, a hyperpolarizing factor may contribute to the vascular adaptation to pregnancy.

Fowlpox virus encodes nonessential homologs of cellular alpha-SNAP, PC-1, and an orphan human homolog of a secreted nematode protein

The genome of fowlpox virus (FWPV), type species of the Avipoxviridae, is considerably rearranged compared with that of vaccinia virus (the prototypic poxvirus and type species of the Orthopoxviridae) and is 30% larger. It is likely that the genome of FWPV contains genes in addition to those found in vaccinia virus, probably involved with its replication and survival in the chicken. A 7,470-bp segment of the FWPV genome has five open reading frames (ORFs), two of which encode ankyrin repeat proteins, many examples of which have been found in poxviruses. The remaining ORFs encode homologs of cellular genes not reported in any other virus. ORF-2 encodes a homolog of the yeast Sec17p and mammalian SNAP proteins, crucial to vesicular transport in the exocytic pathway. ORF-3 encodes a homolog of an orphan human protein, R31240_2, encoded on 19p13.2. ORF-3 is also homologous to three proteins (YLS2, YMV6, and C07B5.5) from the free-living nematode Caenorhabditis elegans and to a 43-kDa antigen from the parasitic nematode Trichinella spiralis. ORF-5 encodes a homolog of the mammalian plasma cell antigen PC-1, a type II glycoprotein with exophosphodiesterase activity. The ORFs are present in the virulent precursor, HP1, of the sequenced attenuated virus (FP9) and are conserved in other strains of FWPV. They were shown, by deletion mutagenesis, to be nonessential to virus replication in tissue culture. RNA encoding the viral homolog of PC-1 is expressed strongly early and late in infection, but RNAs encoding the homologs of SNAP and R31240_2 are expressed weakly and late.

Loss of cell surface microvilli on rat basophilic leukaemia cells precedes secretion and can be mimicked using the calmodulin antagonist trifluoperazine

OBJECTIVE

We studied changes in cell surface morphology following treatment with secretagogue or trifluoperazine in a mast cell model.

MATERIALS AND METHODS

Rat basophilic leukaemia (RBL) cells were treated with antigen and or the calmodulin antagonist, 0-50 microM trifluoperazine (TFP). The release of a secretory granule enzyme, beta-hexosaminidase, into the external medium was used as a measure of secretion. Quantitation of cell surface microvilli was determined by using a computer with input from a digitising tablet from scanning electron micrographs. Cytoskeletal proteins present in microvilli were analysed by confocal immunofluorescence.

RESULTS

When RBL cells are stimulated to secrete with an antigen, the cell surface is transformed from a microvillous morphology to a ruffled one. The cell surface rearrangement preceded beta-hexosaminidase secretion: the majority of microvilli disappeared rapidly after stimulation (t1/2 of 39 s) whereas secretion can only be measured after a lag of 47 s. The calmodulin antagonist, TFP did not inhibit antigen-induced secretion or loss of microvilli, however TFP alone caused a similar loss of microvilli but was unable to stimulate or potentiate secretion. The microvilli mostly disappeared within 30 s, and a half-maximal effect occurred at approximately 8 microM TFP. Using immunofluorescence, calmodulin was localized to punctate structures on the dorsal cell surface which presumably correspond to the microvilli, and which also stained for F-actin and myosin I.

CONCLUSIONS

Loss of cell surface microvilli on RBL cells precedes secretion and could reflect a cytoskeletal rearrangement which facilitates fusion of secretory granules with the membrane. It can be mimicked using trifluoperazine and we suggest it may involve calmodulin-binding components of the microvillus cytoskeleton such as myosin I.

The variation with gestational age of the rheological properties of the blood of the new-born

A study has been made of the variation of blood viscosity and related factors with the gestational age of neonates from 24 weeks to normal term. Viscosity increases significantly over this period by 36% at high shear rate (128.5 s-1) and 250% at low shear (0.277 s-1). The high shear rate changes can be explained largely by the effects of variations in haematocrit and plasma viscosity. At low shear rate the same factors are involved together with changes in the plasma protein composition, in particular the age-related increase in the concentration of the proteins known to induce rouleaux formation. The variation in the degree of sialination of fibrinogen with gestational age may also play a part.