Practice preferences of ophthalmic anaesthesia for cataract surgery in Singapore

INTRODUCTION

This study aims to describe the preferences of ophthalmic anaesthesia for cataract extraction among ophthalmologists in Singapore.

METHODS

A nationwide questionnaire survey of all cataract surgeons in institutional and private practice in Singapore was conducted in August 2004.

RESULTS

The response rate was 61.1 percent (88 out of 144 eligible ophthalmologists surveyed). Phacoemulsification was the preferred surgical technique for 92 percent of the respondents while extra-capsular cataract extraction was preferred by eight percent. For all surgeons performing phacoemulsification, the anaesthesia technique of choice was peribulbar anaesthesia for 43 percent, topical anaesthesia for 42 percent, retrobulbar anaesthesia for 13 percent, and sub-tenons and general anaesthesia for one percent each of the respondents. For all the surgeons performing extra-capsular cataract extraction, the preferred anaesthetic technique was peribulbar anaesthesia for 69 percent, retrobulbar anaesthesia for 30 percent and sub-tenons anaesthesia for one percent of the respondents. The surgeons' main reasons for choosing a specific anaesthesia modality for their surgery were patient comfort and surgeon's choice. The majority of surgeons used mild sedation and monitored anaesthesia care for their cataract surgeries.

CONCLUSION

Peribulbar anaesthesia is currently the preferred anaesthesia technique for both phacoemulsification and extra-capsular cataract extraction in Singapore. Topical anaesthesia closely follows peribulbar anaesthesia as a preferred choice for phacoemulsification.

The lipoprotein lipase S447X polymorphism and plasma lipids

We studied 4,058 subjects from a representative sample of the Singapore population 1) to determine the association between the S447X polymorphism at the LPL locus and serum lipid concentration in Chinese, Malays, and Asian Indians living in Singapore and 2) to explore any interactions with apolipoprotein E (APOE) genotype, exercise, obesity, cigarette smoking, and alcohol intake. Information on obesity, lifestyle factors (including smoking, alcohol consumption, and exercise frequency), glucose tolerance, and fasting lipids was obtained. Male and female carriers of the X447 allele had lower serum triglyceride concentrations and higher HDL cholesterol (HDL-C) concentrations. The association between the X447 allele and serum HDL-C concentration was modulated by APOE genotype in males and cigarette smoking and alcohol intake in females. The effect of the X447 allele was greatest in men who carried the E4 allele and women who smoked or consumed alcohol. The X447 allele at the LPL locus is common and associated with a less atherogenic lipid profile in Asian populations. Interactions with APOE genotype, cigarette smoking, and alcohol intake reinforce the importance of examining genetic associations, such as this one, in the context of the population of interest.

APOE polymorphism and lipid profile in three ethnic groups in the Singapore population

BACKGROUND

Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians.

METHODS

This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus.

RESULTS

Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays.

CONCLUSION

Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.

Evaluation of different promoters driving the GFP reporter gene and selected target tissues for particle bombardment of Dendrobium Sonia 17

Three different morphological callus types, identified as type A, B and C, and tips of in vitro inflorescences were used as target tissues for genetic transformation. Five different DNA plasmids carrying a synthetic green fluorescent protein (gfp) gene driven by different promoters, CaMV 35S, HBT, and Ubi1 were tested for the genetic transformation of Dendrobium Sonia 17. 35S-sgfp-TYG-nos (p35S) with the CaMV 35S promoter showed the highest GFP transient expression rate, while the HBT and Ubi1 promoters showed a relatively lower expression rate in all of the target tissues tested. The highest number of GFP-expressing cells was observed on day 2 post-bombardment, and the number declined gradually over the course of the next 2 weeks. Type A and B callus were found to be the best potential target tissues for genetic transformation.

Effect of soil moisture on seed germination, plant growth and root rot severity of navy bean in Fusarium solani infested soil

The development of root rot and its severity were affected by numerous factors which through their interaction could distort results. In this study, a single factor, soil moisture was considered. Using Fusarium solani infested root rot soil we investigated the effect of three available soil moisture (ASM) levels (i.e. 100%, 70% and 25%) on seed rot, germination, plant growth and root rot severity of navy bean in the greenhouse. Percent germination differed strikingly averaging of 58.5, 89.5 and 87.0% respectively to ASM levels. Apparently, high soil moisture promoted seed rot and impeded seed germination. Root rot incidence and severity were examined two months later. Percent plant with root rot averaged 89.5, 89.0 and 69.8% while root rot severity was 3.01, 2.3 and 1.1 (on a 0-9 scale), respectively to ASM levels. Plant growth was moderate, good and poor with respect to ASM levels. It was apparent that the final plant growth was a sum of seed rot, root rot incidence, disease severity and soil moisture adequacy. However, seed rot appeared to be the largest contributing factor to final plant yield.

Runoff and drainage losses of atrazine, metribuzin, and metolachlor in three water management systems

Rainfall can transport herbicides from agricultural land to surface waters, where they become an environmental concern. Tile drainage can benefit crop production by removing excess soil water but tile drainage may also aggravate herbicide and nutrient movement into surface waters. Water management of tile drains after planting may reduce tile drainage and thereby reduce herbicide losses to surface water. To test this hypothesis we calculated the loss of three herbicides from a field with three water management systems: free drainage (D), controlled drainage (CD), and controlled drainage with subsurface irrigation (CDS). The effect of water management systems on the dissipation of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one), and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] in soil was also monitored. Less herbicide was lost by surface runoff from the D and CD treatments than from CDS. The CDS treatment increased surface runoff, which transported more herbicide than that from D or CD treatments. In one year, the time for metribuzin residue to dissipate to half its initial value was shorter for CDS (33 d) than for D (43 d) and CD (46 d). The half-life of atrazine and metolachlor were not affected by water management. Controlled drainage with subsurface irrigation may increase herbicide loss through increased surface runoff when excessive rain is received soon after herbicide application. However, increasing soil water content in CDS may decrease herbicide persistence, resulting in less residual herbicide available for aqueous transport.

Two case reports on incessant left ventricular tachycardia: curative therapy with radiofrequency ablation

INTRODUCTION

Incessant ventricular tachycardia is a rare arrhythmia which can be life threatening. Treatment with anti-arrhythmic agents may occasionally fail.

CLINICAL PICTURE

We report 2 cases of incessant ventricular tachycardia. The first case was a young man with idiopathic left ventricular tachycardia who was in incessant ventricular tachycardia despite treatment with multiple anti-arrhythmic drugs and developed dilated cardiomyopathy. The second case was an asymptomatic girl with the incidental finding of an incessant ventricular tachycardia which originated from the left ventricular outflow tract.

TREATMENT AND OUTCOME

Both patients underwent electrophysiologic study and radiofrequency ablation with complete termination of the tachycardia.

CONCLUSION

Radiofrequency catheter ablation in experienced centres should be the first-line therapy for incessant ventricular tachycardia.

Effect of long-term conventional tillage and no-tillage systems on soil and water quality at the field scale

No-tillage (NT) is becoming increasingly attractive to farmers because it clearly reduces soil erosion and production costs relative to conventional tillage (CT). However, the impacts of no-tillage on the quantity and quality of tile drainage water are less well known. Accordingly, two adjacent field scale on-farm CT and NT sites were established to compare the impacts of the two tillage systems on tile drainage and NO3-N loss in tile drainage water. The effect of the two tillage systems on soil structure, hydraulic conductivity, and earthworm population were also investigated. The total NO3-N loss in tile drainage water over the 5-yr period (1995-1999) was 82.3 kg N ha(-1) for the long-term NT site and 63.7 kg N ha(-1) for the long-term CT site. The long-term NT site had 48% more tile drainage (6,975 kL ha(-1)) than the long-term CT site (4,716 kL ha(-1)). The average flow weighted mean (FWM) NO3-N concentration in tile drainage water over the 5-yr period was 11.8 mg N L(-1) for the NT site and 13.5 mg N L(-1) for the CT site. For both tillage systems, approximately 80% of tile drainage and NO3-N loss in tile drainage water occurred during the November to April non-growing season. Long-term NT improved wet aggregate stability, increased near-surface hydraulic conductivity and increased both the number and mass of earthworms relative to long-term CT. The greater tile drainage and NO3-N loss under NT were attributed to an increase in continuous soil macropores, as implied by greater hydraulic conductivity and greater numbers of earthworms.

Water table management reduces tile nitrate loss in continuous corn and in a soybean-corn rotation

Water table management systems can be designed to alleviate soil water excesses and deficits, as well as reduce nitrate leaching losses in tile discharge. With this in mind, a standard tile drainage (DR) system was compared over 8 years (1991 to 1999) to a controlled tile drainage/subirrigation (CDS) system on a low-slope (0.05 to 0.1%) Brookston clay loam soil (Typic Argiaquoll) in southwestern Ontario, Canada. In the CDS system, tile discharge was controlled to prevent excessive drainage, and water was pumped back up the tile lines (subirrigation) to replenish the crop root zone during water deficit periods. In the first phase of the study (1991 to 1994), continuous corn (Zea mays, L.) was grown with annual nitrogen (N) fertilizer inputs as per local soil test recommendations. In the second phase (1995 to 1999), a soybean (Glycine max L., Merr.)-corn rotation was used with N fertilizer added only during the two corn years. In Phase 1 when continuous corn was grown, CDS reduced total tile discharge by 26% and total nitrate loss in tile discharge by 55%, compared to DR. In addition, the 4-year flow weighted mean (FWM) nitrate concentration in tile discharge exceeded the Canadian drinking water guideline (10 mg N l(-1)) under DR (11.4 mg N l(-1)), but not under CDS (7.0 mg N l(-1)). In Phase 2 during the soybean-corn rotation, CDS reduced total tile discharge by 38% and total nitrate loss in tile discharge by 66%, relative to DR. The 4-year FWM nitrate concentration during Phase 2 in tile discharge was below the drinking water guideline for both DR (7.3 mg N l(-1)) and CDS (4.0 mg N l(-1)). During both phases of the experiment, the CDS treatment caused only minor increases in nitrate loss in surface runoff relative to DR. Hence CDS decreased FWM nitrate concentrations, total drainage water loss, and total nitrate loss in tile discharge relative to DR. In addition, soybean-corn rotation reduced FWM nitrate concentrations and total nitrate loss in tile discharge relative to continuous corn. CDS and crop rotations with reduced N fertilizer inputs can thus improve the quality of tile discharge water substantially.

Tillage, intercrop, and controlled drainage-subirrigation influence atrazine, metribuzin, and metolachlor loss

Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] have been found with increasing occurrence in rivers and streams. Their continued use will require changes in agricultural practices. We compared water quality from four crop-tillage treatments: (i) conventional moldboard plow (MB), (ii) MB with ryegrass (Lolium multiflorum Lam.) intercrop (IC), (iii) soil saver (SS), and (iv) SS + IC; and two drainage control treatments, drained (D) and controlled drainage-subirrigation (CDS). Atrazine (1.1 kg a.i. ha-1), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one] (0.5 kg a.i. ha-1), and metolachlor (1.68 kg a.i. ha-1) were applied preemergence in a band over seeded corn (Zea mays L.) rows. Herbicide concentration and losses were monitored from 1992 to spring 1995. Annual herbicide losses ranged from < 0.3 to 2.7% of application. Crop-tillage treatment influenced herbicide loss in 1992 but not in 1993 or 1994, whereas CDS affected partitioning of losses in most years. In 1992, SS + IC reduced herbicide loss in tile drains and surface runoff by 46 to 49% compared with MB. The intercrop reduced surface runoff, which reduced herbicide transport. Controlled drainage-subirrigation increased herbicide loss in surface runoff but decreased loss through tile drainage so that total herbicide loss did not differ between drainage treatments. Desethyl atrazine [6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine] comprised 7 to 39% of the total triazine loss.

Initial experience with an autocapture pacemaker system

INTRODUCTION

Autocapture management aims to extend pacemaker longevity without compromising on patient safety by automatically monitoring the pacing threshold and adjusting the pacemaker output for consistent capture. This paper describes our initial experience with the Pacesetter Regency pacemaker with autocapture management.

MATERIALS AND METHODS

Nineteen patients were implanted with single chamber pacemakers with autocapture management. Autocapture was programmed "ON" the day after implantation if Evoked Response (ER) amplitude was at least 2.8 mV. The patients were followed up at 2 weeks, 2 months and 6 months. At each visit, pacing threshold and lead impedance were measured. Autocapture was turned "ON" during follow-up if it had not been done previously.

RESULTS

In 16 out of 19 patients, autocapture could be turned "ON" the day after implantation. One patient had an ER signal that was less than 2.8 mV and 2 patients were in fast atrial fibrillation of more than 120 beats per minute which precluded ER signal testing. These patients could not have autocapture programmed "ON".

CONCLUSION

The benefits of autocapture management can only be realised if an ER signal of at least 2.8 mV is obtained. This requires intraoperative testing of the ER signal. Since there is no commercially available pacing system analyser presently that can measure this, modification of the standard implantation procedure with some prolongation of procedure time is needed.

Toward the differentiation of trust in supervisor and trust in organization

Trust in supervisor and trust in organization are argued to be distinct but related constructs, each with its own set of antecedents and outcomes. Empirical field results supported the proposition. Although trust in supervisor and trust in organization were positively and significantly correlated, trust in supervisor was more strongly associated with proximal variables (ability, benevolence, and integrity of supervisor), whereas trust in organization was more strongly correlated with global variables (perceived organizational support and justice). This conclusion held despite the inclusion of proximal variables in the regression on trust in organization and the inclusion of global variables in the regression on trust in supervisor. In addition to the differential antecedents of trust in supervisor and trust in organization, the outcomes for both variables were different. Trust in supervisor was related to increased innovative behavior and satisfaction with supervisor, and trust in organization was related to higher organizational commitment and lower intention to leave. Therefore, the authors provide clear preliminary data on the distinctiveness of trust in supervisor and trust in organization. One implication of this set of results is that organizations should adopt a more holistic approach in building trust, which can be achieved by focusing on the various constituents of the organization and the various levels (e.g., the supervisor level and the organizational level).

Reassessing the organization of the UL42-UL43 region of the human cytomegalovirus strain AD169 genome

A polymorphism in the UL42-UL43 region of the human cytomegalovirus genome has been characterized by nucleotide sequence analysis, revealing a 929-bp insertion following nt 54,612 relative to the published strain AD169-UK genome sequence (M.S. Chee et al., 1990, Curr. Top. Microbiol Immunol. 154, 125-170). Although AD169-UK exhibited polymorphism in this genomic region, other CMV strains (Towne, Toledo, and AD169-ATCC) carried only the newly characterized longer form. The additional sequence altered the assignment of UL42 and UL43 open reading frames. UL42 decreased in size from 157 to 125 codons, retaining 76 of the previously reported carboxyl terminal codons, and UL43 increased in size from 187 to 423 codons, retaining 185 of the previously reported amino terminal codons. This additional sequence makes UL43 a more conserved betaherpesvirus US22 family member. Only AD169-UK exhibited restriction fragment length polymorphism in this region, suggesting that a deletion occurred during the propagation of this strain in cell culture. The additional sequence should be considered a bona fide part of the cytomegalovirus genome and the AD169 genome size should be corrected to 230,283 bp.

Molecular taxonomy and GC/MS of metabolites of Scytalidium hyalinum and Nattrassia mangiferae (Hendersonula toruloidea)

ARDRA of ribosomal genes confirmed that the hyphomycete Scytalidium hyalinum is identical to the coelomycete Nattrassia mangiferae (Hendersonula toruloidea, with arthroconidial synanamorph Scytalidium dimidiatum). S. hyalinum may be just a melanin-less cultural mutant of S. dimidiatum. This explains why the two species are regularly found in the same patient population as agents of human dermatomycosis. Two strains from plant sources were found to be identical to the human strains in ITS-RFLP patterns. RFLP of SSU and LSU was hampered by the frequent occurrence of introns. Profiles of secondary metabolites were studied using TLC, GC and GC/MS. Production of metabolites varies considerably with the strain, but two naphthoquinone compounds were nearly always present. Selected-ion monitoring (SIM) of these compounds enabled the specific recognition of the taxon.

[Fungi and yeasts isolated in mycological studies in skin and nail infections in The Netherlands, 1992-1993]

OBJECTIVE

To describe fungi and yeasts isolated from skin and nail infections in the Netherlands.

DESIGN

Retrospective.

SETTING

Centraalbureau voor Schimmelcultures (CBS), Baarn, the Netherlands.

METHOD

Results of mycological investigation of skin and nail samples in the period 1992-1993 were analysed. After a clinical diagnosis of mycosis, performed by dermatologists and general practitioners, material was sent to the CBS for mycological research.

RESULTS

The clinical diagnosis of onychomycosis was rather accurate, especially if made performed by dermatologists. Mycoses of the skin were sometimes confused with other skin diseases. When microscopical observation showed a positive result, 93% of the cultures were positive as well. The main agent of onychomycosis was Trichophyton rubrum; T. mentagrophytes was more frequently isolated from tinea manuum/pedis and T. tonsurans from tinea corporis/cruris. Epidermophyton floccosum was only isolated from skin lesions and Microsporum canis, T. soudanense and T. verrucosum only from tinea corporis/cruris. The most important yeasts isolated were Trichosporon mucoides, Candida guilliermondii, C. parapsilosis, C. famata and Malassezia furfur. Other fungi isolated were either pigmented (melanin, carotene), thermophilic or belonged to the order of the Onygenales.

CONCLUSION

Mycological research to confirm the clinical diagnosis of a skin mycosis is advisable. Species isolated differed in their predilection for different parts of the human body. Yeasts were mainly isolated as double infections. Apart from the dermatophytes there is a special group of fungi which can cause mycoses.

Structural and functional properties of human and mouse apolipoprotein A-I

Mouse and human plasma apolipoprotein A-I (apo A-Im and apo A-Ih, respectively) were investigated to compare their molecular properties in solution, their incorporation into palmitoyloleoylphosphatidylcholine-apo A-I (POPC-apo A-I) discoidal complexes; their structural stability in discoidal complexes and high-density lipoproteins (HDL), and their effect on structural rearrangement of discoidal complexes upon interaction with low-density lipoproteins (LDL). Unlike apo A-Ih, only minimal concentration-dependent self-association was observed for apo A-Im. While both apo A-Im and apo A-Ih formed discoidal complexes of distinct composition and size that reflected reassembly molar ratios of POPC/apo A-I, apo A-Im demonstrated specific deficiencies in formation of larger-sized complexes. Denaturation of both apo A-Im- or apo A-Ih-containing complexes and HDL with guanidine hydrochloride (GuHCl) indicated significantly reduced stabilization of apo A-Im by lipid in these particles. Interaction of apo A-Im- or apo A-Ih-containing discoidal complexes with human plasma LDL revealed a more extensive conversion of apo A-Im-complexes to smaller species. Mean hydrophobicities and mean hydrophobic moments of amphipathic helical segments in apo A-Im and apo A-Ih were compared; differences potentially contributing to differential lipid-binding properties between apo A-Im and apo A-Ih were identified. Our results demonstrate differences between apo A-Im and apo A-Ih that may contribute to the major changes in plasma HDL distribution and function observed in apo A-Ih transgenic mice.

Diagnostic problems with imported cases of mycetoma in The Netherlands

Eight cases of imported mycetomata in The Netherlands are reviewed. Seven of these were cultured; only one isolate, Actinomadura madurae, belonged to a species commonly known as an agent of mycetoma. The remaining strains either belonged to very rare species, such as Phialophora cyanescens, or could not be identified at all. The list of possible agents of mycetoma apparently needs to be expanded. In addition, the concept of endemic occurrence of aetiological agents of eumycetoma needs revision. Divergent saprophytes may be involved which are able to survive in human tissue.

The spectrum of opportunistic filamentous fungi present in the CBS culture collection

The mould collection of the Centraalbureau voor Schimmelcultures, Baarn, The Netherlands, was screened for isolates originating from warm-blooded animals. The range of species indicates that distribution of clinically relevant, pathogenic or opportunistic strains over the fungal kingdom is non-random. Some opportunistic fungi possess adaptations to life under hostile environmental conditions, enabling them to survive inside the human body. Presence of melanin or carotene seems to be an important virulence factor. Opportunistic fungi which sporulate in submersion are able to disseminate or cause severe local mycoses when the aspecific immune system of the host is impaired. Mycoses caused by a few dimorphic fungi, mostly in their natural ecological niche living in association with vertebrates, are promoted by specific immune deficiencies.

[Shifts in the species spectrum of mycoses in The Netherlands from 1970-1990]

A review is presented of yeast and mould infections occurring in humans in the Netherlands. The occurrence of the dermatophytes Trichophyton rubrum and T. mentagrophytes tends to increase, while Microsporum canis and particularly Epidermophyton floccosum have become less common. The yeast Candida glabrata is particularly often involved in infections of the urinary tract. Candida krusei, C. parapsilosis and C. tropicalis have become less significant. Remarkable differences are found between the spectra of Aspergillus species causing infections in lungs and in ears; an entirely different pathogenesis is to be presumed. The number of systemic mycoses in the Netherlands is underestimated. The possibility of hundreds of cases each year cannot be excluded.

[Little known mycoses caused by dematiaceous opportunists]

The mycoses caused by melanized hyphomycetes are reviewed. Agents of superficial, (sub)cutaneous, paranasal, and systemic mycoses are listed, putting the emphasis on species isolated in Germany. Adaptations to survive in extreme environments may be considered as virulence factors of these fungi. Survival inside human tissue is more or less successful depending on the immune status of the host. Several neurotropic fungi are possibly real pathogens in that they are capable of invading immunocompetent individuals.

Root growth and water uptake by wheat during drying of undisturbed and repacked soil in drainage lysimeters

The dynamics of root development and water uptake in undisturbed and repacked clay soil were studied during increasing soil water deficit pre- and post-anthesis to find how root distribution, soil type and plant development affect plant available water (PAW). Volumetric water fraction was measured with a neutron probe, while root distribution was measured non-destructively using a series of horizontal perspex observation tubes. Soil modification affected the downward root growth which changed little over time for undisturbed (U) soil (6.7-13.6 mm/d) compared with the repacked (R) soil (7.5-42.9 mm). In the well-watered treatments root distribution was mostly above the 0.55 m depth in U soil, while there was a reasonably uniform vertical distribution in R soil. The rate of root growth during post-anthesis drying was 61% of that during pre-anthesis drying. The specific root water uptake rate (vol./unit root length/time) was linearly related to the relative root growth rate, indicating the importance of root growth in supplying water during soil drying. Estimated PAW values reflected effects of soil hydraulic properties, root distribution and a propensity to grow new roots during soil drying. Differences in grain yield between treatments were thought to result from the effects of different root distributions and the propensity to grow roots during soil drying.

A comparative study of the enzymatic and toxic properties of venoms of the Asian lance-headed pit viper (Genus Trimeresurus)

1. The lethalities, anticoagulant effects, hermorrhagic, thrombin-like enzyme, hyaluronidase, protease, arginine ester hydrolase, 5'-nucleotidase, L-amino acid oxidase, alkaline phosphomonoesterase, phosphodiesterase and phospholipase A activities of twenty-three samples of venoms from twelve species of Asian lance-headed pit vipers (genus Trimeresurus) were examined. 2. The results indicate that notwithstanding individual variations in venom properties, the differences in biological properties of the Trimeresurus venoms can be used for the differentiation of venoms from different species of Trimeresurus. 3. The results also suggest that differences in the biological properties of snake venoms are useful parameters in the classification of snake species. 4. Our results indicate that venoms from the species T. okinavensis exhibited biological properties markedly different from other Trimeresurus venoms examined. This observation supports the recently proposed reclassification of T. okinavensis as a member of the genus Ovophis, rather than the genus Trimeresurus.

The enzymatic activities and lethal toxins of Trimeresurus wagleri (speckled pit viper) venom

Trimeresurus wagleri (speckled pit viper) venom exhibited the usual set of enzyme activities occurring in pit viper venoms but the content of alkaline phosphomonoesterase was unusually high, whereas the proportions of protease and arginine ester hydrolase were very low. The venom also exhibited weak thrombin-like activity but did not exhibit hemorrhagic or anticoagulant activity. Analysis of the Sephadex G-200 gel filtration fractions of the venom indicated that the lethal fraction was a low mol.wt protein, and that fractions exhibiting phosphodiesterase, phosphomonoesterase, arginine ester hydrolase, thrombin-like enzyme, L-amino acid oxidase and phospholipase A activities were not lethal. Two lethal toxins, designated as wagleri toxins 1 and 2, were isolated from the venom using Sephadex G-50 gel filtration chromatography followed by SP-Sephadex C-25 ion exchange chromatography. The mol.wts of the two toxins were 8900 by gel filtration. The LD50 (i.v.) values in mice for wagleri toxins 1 and 2 are 0.17 microgram/g and 0.19 microgram/g, respectively.

Fractionation of Sumatran pit viper (Trimeresurus sumatranus sumatranus) venom by DEAE-Sephacel ion exchange chromatography and some biological properties of the fractions

Sumatran pit viper (Trimeresurus sumatranus sumatranus) venom was fractionated by DEAE-Sephacel ion exchange chromatography into seven fractions. Fractions 4, 5 and 6 were lethal to mice and exhibited strong hemorrhagic activity, as well as some enzymatic activities. Fraction 6 also exhibited potent anticoagulant and thrombin-like activities. Analysis of the biological and enzymatic properties of the three lethal fractions suggests that the major lethal component of fractions 4 and 5 may be the hemorrhagic principle, and that the lethality of fraction 6 may be due to the hemorrhagic principle and/or the anticoagulant principle.

The lethal and biochemical properties of Bungarus candidus (Malayan krait) venom and venom fractions

Bungarus candidus venom exhibited high hyaluronidase, acetylcholinesterase and phospholipase A activities; low proteinase, 5'-nucleotidase, alkaline phosphomonoesterase and phosphodiesterase activities and moderately high L-amino acid oxidase activity. SP-Sephadex C-50 ion exchange chromatographic fractionation of the venom and Sephadex G-50 chromatography of the major lethal venom fractions indicate that the venom contains at least two highly lethal, basic phospholipases A with LD50 (i.v.) values of 0.02 micrograms/g (F6A) and 0.18 micrograms/g (F4A), respectively; as well as two polypeptide toxins with LD50 (i.v.) values of 0.17 micrograms/g and 0.83 micrograms/g, respectively. The major lethal toxin is the basic lethal phospholipase A, F6A, which accounts for approximately 13% of the venom protein and has a mol. wt of 21,000.

Acidimetric assay for phospholipase A using egg yolk suspension as substrate

A convenient acidimetric assay for phospholipase A using egg yolk suspension as substrate has been developed. The substrate mixture consists of 1 part egg yolk, 1 part 8.1 mM sodium deoxycholate, and 1 part 18 mM calcium chloride. Phospholipase A activity is measured by following the initial rate of pH change, which is linear between pH 8.0 and 7.75 and is proportional to enzyme concentration over a wide range. The assay is highly reproducible, with a coefficient of variation of 3%, and as sensitive as most established assays for phospholipase A. The assay uses inexpensive and easily available substrate and is simple to perform. It is particularly useful for monitoring phospholipase A activity in chromatography fractions.

Atypical transmural thoracic lipoma: CT diagnosis

Two cases of transmural thoracic lipomas demonstrate a pattern of rib involvement that has not been previously reported. The lipomas presented with an otherwise characteristic appearance on plain radiography and CT.

Partial purification of acetylcholinesterase from the venom of the shore pit viper (Trimeresurus purpureomaculatus)

Trimeresurus purpureomaculatus venom acetylcholinesterase has been partially purified by Sephadex G-200 gel filtration chromatography and DEAE Sephacel ion exchange chromatography. The enzyme has a mol. wt of 58,600. It was strongly inhibited by physostigmine salicylate and edrophonium chloride and exhibited substrate inhibition at high substrate concentration. The content of acetylcholinesterase in Trimeresurus purpureomaculatus venom was estimated to be much less than 0.3%.

A comparative study of cobra (Naja) venom enzymes

1. The L-amino acid oxidase, hyaluronidase, alkaline phosphomonoesterase, protease, phosphodiesterase, acetylcholinesterase, phospholipase A and 5'-nucleotidase activities of 47 samples of venoms from all the six species of cobra (Naja), including five subspecies of Naja naja, were examined. 2. The results demonstrated interspecific differences in the venom contents of phospholipase A, acetylcholinesterase, hyaluronidase and phosphodiesterase. These differences in venom enzyme contents can be used for the differentiation of species of the genus Naja. 3. Thus, our results revealed a correlation between the enzyme composition of venom and the taxonomic status of the snake at the species level for the genus Naja.

Enzymatic activities of Malayan cobra (Naja naja sputatrix) venoms

The enzymatic activities of four samples of Malayan cobra venom were investigated. There was significant variation in the contents of L-amino acid oxidase, alkaline phosphomonoesterase, acetylcholinesterase, phospholipase A, 5'-nucleotidase and hyaluronidase. The phosphodiesterase content was, however, constant. Storage of the lyophilized venom powder at 25 degrees C for 1 month did not affect the enzymatic activities. The venom enzymatic activities were generally also stable at 4 degrees C in 0.85% saline solution. After incubation at 37 degrees C for 39 days in 0.85% saline solution, the venom still retained considerable amounts of enzymatic activities. SP-Sephadex C-25 ion-exchange chromatography of the venom showed that the phospholipase A, L-amino acid oxidase, 5'-nucleotidase, phosphodiesterase and alkaline phosphomonoesterase exist in multiple forms.

Enzymatic activities of Calloselasma rhodostoma (Malayan pit viper) venom

The enzyme contents of four venom samples of Calloselasma rhodostoma were analyzed. The venoms contained phosphodiesterase, alkaline phosphomonoesterase, 5'-nucleotidase, protease, phospholipase A, L-amino acid oxidase, hyaluronidase, arginine ester hydrolase, arginine amidase, fibrinogenase and coagulant enzyme activities. There is significant variation in the contents of coagulant enzyme, arginine ester hydrolase, hyaluronidase, protease, phosphodiesterase, alkaline phosphomonoesterase and L-amino acid oxidase. DEAE-Sephacel ion exchange chromatography of the venom resolved it into eight major protein fractions. The eight fractions were heterogeneous and exhibited more than one type of enzymatic activity. The 5'-nucleotidase, alkaline phosphomonoesterase, protease, coagulant enzyme, arginine ester hydrolase, arginine amidase and fibrinogenase exist in multiple forms.

Pneumothorax and subcutaneous emphysema complicating endotracheal intubation

We report subcutaneous emphysema and pneumothorax as immediate complications of endotracheal intubation in a patient with diffuse interstitial lung disease. We postulate increased intra-alveolar pressure during intubation leading to rupture of a subpleural bleb or cyst as a possible mechanism causing these complications.

Effect of assisted ventilation on respiratory drive of normal anesthetized dogs

We measured the diaphragm electromyogram (EMGd) and airway occlusion pressure (P100) of anesthetized dogs at the ends of 30-min of alternating spontaneous breathing and assisted mechanical ventilation (inspiratory positive pressure triggered by a minimal inspiratory effort; IPPB). Peak airway pressures (Paw) of 5, 10, 15, and 20 cm H2O were applied in random order during IPPB. The initial rate of rise of EMGd (4 experiments) and P100 (9 experiments) decreased during IPPB, both in proportion to the Paw. At Paw of 20 cm H2O, PaCO2, EMGd and P100 decreased on the average 5.2 Torr, 58% and 56%, respectively. When PaCO2 was kept the same during IPPB as during spontaneous breathing (8 experiments), IPPB reduced EMGd and P100 15% and 24% respectively, both statistically significant. During progressive cooling of both cervical vagi, the effect of IPPB (Paw=20 cm H2O) on EMGd and P100 decreased progressively, near maximal at 6--4 degrees C and after vagotomy. However, the decrease in PaCO2 during IPPB was not affected. These data suggest that increasing tidal volume during IPPB depresses respiratory drive (EMGd and P100), partially from decreased PaCO2 and partially from stimulating pulmonary stretch receptors. The drop in PaCO2 during IPPB does not appear to be vagally mediated.

Supernormal maximal mid-expirartory flow rates in diffuse interstitial lung disease

We studied the frequency of changes in maximal mid-expiratory flow rate (MMF) in 32 nonsmokers and 22 smokers with diffuse interstitial lung disease (DILD) and in 36 health nonsmoking control subjects. Supernormal MMF to total lung capacity (TLC) and MMF to forced vital capacity (FVC) ratios (greater than 120% of predicted) were significantly more common in nonsmokers with DILD than in healthy nonsmokers, but the prevalence of supernormal forced expired volume in 1 s (FEV1) to FVC ratios was similar. In non-smokers with DILD, a supernormal MF/TLC ratio was associated with a significantly greater static lung recoil pressure (Pst) and a tendency toward a higher maximal expiratory flow to Pst ratio than in normals, suggesting that the increased MMF is due to the combined effects of increased driving pressure for flow and reduced resistance in peripheral airways.