Orbital cavernous hemangioma of childhood

Ocular and orbital tumors, both benign and malignant, occur relatively frequently in infants and children. Benign masses are much more common than malignant in the orbital region. However, childhood tumors show great variability and it is difficult to differentiate benign from malignant lesions. Cavernous hemangioma is the most common benign neoplasm of the orbit in adults. We report a case of orbital cavernous hemangioma in a four-year-old girl presenting as unilateral painless proptosis.

IL-6 protects enterocytes from hypoxia-induced apoptosis by induction of bcl-2 mRNA and reduction of fas mRNA

Interleukin-6 (IL-6) has been shown to rescue enterocytes from hypoxia-induced apoptosis when given orally following hemorrhagic shock. In vitro models using an intestinal epithelial cell line (IEC-6) cultured with lipopolysaccharide (LPS) under low O2 conditions, to mimic intestinal conditions, show that these cells also undergo apoptosis, which can be reduced by subsequent culture with IL-6. To examine further the mechanisms of rescue, we cultured normal rat intestinal epithelial cells (IEC-6) under both normoxic and hypoxic conditions and analyzed their responses to LPS and IL-6. We showed that IEC-6 expressed IL-6 receptor on its surface. Further, IEC-6 cells could be rescued from hypoxia-induced apoptosis by co-culture with IL-6. RNase protection assay (RPA) examination revealed that under hypoxic conditions, IEC-6 cells that were resistant to apoptosis showed reduced fas expression and increased bcl-2 expression after co-culture with LPS+IL-6.

Barrage laser photocoagulation for macula-sparing asymptomatic clinical rhegmatogenous retinal detachments

PURPOSE

To evaluate the efficacy of barrage laser photocoagulation in containing macula-sparing asymptomatic clinical retinal detachments (RD).

METHODS

Consecutive patients presenting with asymptomatic clinical RD were prospectively treated with barrage photocoagulation in 2-3 confluent rows, using frequency-doubled Nd:YAG (532 nm) laser on an indirect-ophthalmoscopic delivery system. The patients were reviewed at 0.5, 1.5, 3, and 6 months, and yearly thereafter. Best-corrected visual acuity (BCVA), and stability/progression of rhegmatous retinal detachment beyond the barrage were noted at each visit.

RESULTS

Nineteen phakic eyes of 17 patients (nine female patients), aged 12-58 years (average: 26 years), underwent barrage laser treatment. Two women had bilateral RD. Most detachments were caused by atrophic holes, and involved at least a quadrant of retina. Seven (37%) extended superiorly with breaks above the horizontal raphe. Three eyes had partial demarcation lines, and five had posterior vitreous detachment at presentation. The minimum follow-up was 6 months (mean: 21 months; range: 6-108 months). Pretreatment anatomical and functional status was maintained in 18 (95%) eyes till the final visit. One superotemporal RD progressed across the laser barrier into macula 5 months after photocoagulation, and BCVA dropped to 6/18. Scleral buckling was performed successfully, with visual recovery to 6/6.

CONCLUSIONS

Barrage photocoagulation may have a place in management of asymptomatic clinical detachments, as an effective and less morbid alternative to scleral buckling.

Structural influence of mono and polyhydric alcohols on the stabilization of collagen

In the present study, solvents effects on the structure of collagen have been examined by circular dichroism and their interfacial tension at glass/liquid and Teflon/liquid. Changes in the conformations of the protein have been analyzed after equilibration with aqueous solutions of monohydric and polyhydric alcohols like methanol, ethanol, n-propanol, propane-2-diol and glycerol. The results from viscosity and Circular dichroism (CD) spectra suggest a clear distinction in the structural changes for collagen with monohydric alcohols as against polyhydric ones. The surface tension and interfacial tension at glass (high surface energy, HFSE) and Teflon (Low surface energy, LSFE) reflect similar differences between the monohydric and polyhydric alcohols. Studies on the interfacial energy of the adsorbed protein at glass/solution interface compared to that of Teflon/solution interface show that the water structure near glass gets perturbed leading to an increase in the average free energy of the bulk water phase and a reduction in hydrophobic effect near the glass. The results suggest that the different solvents alter the hydrophobic effect on the hydrated protein to different extent and thus influence folding equilibrium of the protein without directly interacting with it. Polyhydric alcohols seem to favor the native collagen structure while monohydric alcohols enhance it.

Mucin at solution/air and solid/solution interfaces

In this paper the surface activity of protein mucin at solution/air interface has been studied. The experiments of the adsorbed protein at solution/air interface have been carried out with a range of protein concentrations at a defined pH. The adsorption of the protein to solid surfaces and the degree of hydrophobicity at solid/solution interface of mucin have been evaluated at different pH and in the presence of Hofmeister electrolyte. The results from these studies have been further substantiated by surface potential measurements of mucin covered surface on stainless steel. Quartz crystal microbalance (QCM) has been used to follow the protein adsorption kinetics from solution to solid surface. The results from these measurements show that the adsorption behavior has a remarkable dependence on the degree of maximum coverage and is almost independent of the ionic strength. Other characteristic features such as maximum adsorption values at the protein isoelectric point (IEP4.7) and low-affinity isotherms that showed surface saturation even under unfavorable electrostatic conditions have been observed. The amount of mucin adsorbed in the presence of electrolytes has been estimated using electron spectroscopy for chemical analysis (ESCA). The study clearly shows that there exists an inverse relationship between the hydrophobicity and surface tension of the protein and also on the hydrated radius of Hofmeister electrolyte used.

Congenital eversion of upper eyelids: Case report and management

Congenital eversion of the upper eyelids is a rare condition, the exact cause of which remains unknown. It is more frequently associated with Down's syndrome and black babies. If diagnosed early and treated properly, the condition can be managed without surgery. We report a case of congenital bilateral severe upper eyelid eversion in a normal infant, born by vaginal delivery. The case was conservatively managed by lubricants, antibiotics and eyelid patching.

Solid–liquid interfacial energy as a tool to estimate shifts in isoelectric points of adsorbed proteins on solid surfaces

This work reports the estimation of isoelectric points (pIs) of adsorbed amino acids and proteins on solid surfaces in the pH range between 3.5-11.0 from a measurement of solid/liquid interfacial energy. The values thus obtained are compared with the pIs determined in solution phase by other methods. Both glass and Teflon have been chosen as model solid surfaces. Close agreement between the reference pI values, obtained by the capillary isoelectric focusing and those obtained at solid/liquid interface is observed within an average difference of 0.04-0.08 pH unit when the pIs are above the pI of glass. For systems whose pIs are far away from that of glass (either in the acidic or highly alkaline range), a large shift in the isoelectric point is observed. In case of Teflon the pIs are closer to the reported values than at glass/liquid interface. This could be due to the fact that Teflon being a hydrophobic surface, its surface is dominated by dispersive forces, which may not be seriously affected by pH changes. The shift in the values at solid/liquid interface compared to that in solution have been examined using an 'image charge approach.'

Investigation of surface properties of amino acids: polarity scale for amino acids as a means to predict surface exposed residues in films of proteins

It is of great interest and importance to study how different amino acid residues contribute to and affect the properties of proteins coated as films on solid surface. This work shows that the solid/liquid interfacial energy of surface localized amino acid films and their Gibbs energies of transfer at the air/solution interface have the potential to be used as a rapid and simple method for studying the surface properties of proteins. Based on these results, a new polarity scale for amino acids has been proposed. This scale is compared with existing hydropathy scales in a benchmark test using some proteins with solved 3D structure. The proteins were characterized in terms of surface-exposed residues with a computer program, Graphical Representation and Analysis of Surface Properties (GRASP). It was also shown that each amino acid contribution is relative to the total protein surface and the other residues on the surface.

Results of probing for congenital nasolacrimal duct obstruction in children older than 13 months of age

PURPOSE

To determine the success rate of probing for congenital nasolacrimal duct obstruction in children older than 13 months of age.

METHODS

In a retrospective study of 84 children, 13 months and older who underwent probing for congenital nasolacrimal duct obstruction, the age at probing was correlated with success of probing. The children were divided into two groups, Group 1(13 - 24 months) and Group 2 (>24 months). Success was defined as complete resolution of signs and symptoms. The chi-square test was used to analyse the result.

RESULTS

The success rate was 88.1% in-group 1 and 80.1% in-group 2 (P = 0.84). There was no significant difference in the cure rate with increasing age (P = 0.6).

CONCLUSION

Probing is highly successful in the older age group and should remain the first line of treatment in older children.

Spontaneous recurrent haemarthrosis following unicompartmental knee arthroplasty and its successful treatment by coil embolisation

A case of spontaneous recurrent haemarthrosis of the knee presenting 3 months after the unicondylar knee replacement is described. Femoral arteriography demonstrated hypertrophy of the saphenous branch of descending genicular artery with a prominent vascular blush in the region of posteromedial aspect of the popliteal fossa thought to represent a hypertrophic vascular mass of synovium. Therapeutic embolisation of the saphenous branch of descending genicular artery was performed using three fibred platinum coils with satisfactory clinical results. Since the embolisation, the haemarthrosis has not recurred. To our knowledge, this therapeutic procedure used to treat recurrent haemarthrosis following unicondylar knee arthroplasty has not been previously described in the literature.

Oxidation of benzaldehyde in films by Oxo-Cr(V) salen derivatives at solid/liquid interface

The oxidation of benzaldehyde as a film on a solid surface by various substituted oxochromium(V) salen in solution has been studied by monitoring the change in contact angle of the oxidant at the film/liquid interface utilizing a Teflon cell of known hydrodynamics and controlled convection/diffusion. The kinetics of the redox reaction in bulk has been monitored by measuring the change in absorbance of the oxidant solution. The interfacial study permits analysis of adsorption of the oxidant followed by the oxidation of the substrate under pseudo-first-order conditions. A comparison of the independent surface-averaged kinetic data with those obtained in the solution phase oxidation reaction is made and a model is presented for the mechanism of the interfacial reaction. The kinetic investigation shows that the rate of oxidation is accelerated in the presence of an electron-withdrawing group and is faster at the solid/liquid interface compared to the bulk. The probable mechanism of the redox reaction is discussed.

Influence of ammonium nitrate in phase transitions of Langmuir and Langmuir-Blodgett films at air/solution and solid/solution interfaces

The effect of ammonium nitrate on the phase transitions in Langmuir films of amphiphiles-stearic acid, stearyl amine (STAM), stearyl alcohol, dihexadecylphosphate, and the quarternized ammonium salt dioctadecyldimethylammonium bromide have been studied at air/water interface and in local ordering of their Langmuir-Blodgett films (LB films). The study shows that except for the stearyl amine (STAM) all other monolayers exhibit a liquid-expanded to liquid-condensed transition with slight expansion in area in the presence of ammonium nitrate. STAM monolayers show a new phase transition, which possibly arises due to the differently ionized amino groups, and change in solvation sheath due to an ion-dipole type interaction between the amino groups and the ammonium ion in the subphase. Mixed films of the amine with the acid and alcohol did not show such intermediate phases indicating that competing H-bonds between polar groups themselves and dipolar couplings between the polar groups and ammonium nitrate play a major role in the organization of the molecules at the interface. The above effect resulting in a change in the local order is borne out by Brewster angle micrographs (BAM) of the Langmuir films of STAM at air/solution interface. Such behavior is also seen at solid/liquid interfaces where the polar component of surface energy undergoes a drastic change for the amine films transferred onto solid substrates from the air/ammonium nitrate solution interface.

Molecular dipoles at substrate/film interfaces influencing surface energy of Langmuir–Blodgett films

Langmuir and Langmuir-Blodgett (LB) films of novel rigid Schiff base amphiphiles with different polar groups on aromatic rings have been studied at air/water interfaces and on solid substrates. The local surface potentials for the different substituents on the aromatic groups of the amphiphiles are correlated to the surface energy of LB films on solid substrates. Their contributions are probed on high-surface-energy (hsfe) quartz and hydrophobically modified low-surface-energy (lsfe) quartz. Using theoretical estimates, the long-range effects of the substituents of the polar groups on the alkyl chains have been studied from charge on the carbon and hydrogen atoms of the alkyl tails. The calculations indicate that a substituted carbon atom has a charge that is directly dependent on the nature of the atoms to which it is attached rather than on the charges of any other atoms of the substituents. This work shows that the polar substituents on the head group clearly influence the distal methylene groups of the tail. Thus, any treatment, either theoretical or experimental, of these films in contact with solid substrates should include the local relative permitivities of the polar moieties, which seem to play an important role in determining macroscopic properties such as surface energy.

Evaluation of standardized versus individualized total parenteral nutrition regime for neonates less than 33 weeks gestation

OBJECTIVE

To evaluate the difference in nutrient intakes and biochemical responses in newborn infants <33 weeks gestation who received standardized versus individualized total parenteral nutrition (TPN) regimes.

METHOD

Comparison of nutrient intakes and daily biochemical responses in newborn infants <33 weeks gestation who received standardized regime versus those who received individualized TPN regimes from day 2 to day 7 of life.

RESULTS

Twenty-seven infants in the standardized TPN group and 31 infants in the individualized TPN group were compared. There were no statistically significant differences (P > 0.05) between the two groups in gestation, birthweight, Clinical Risk Index for Babies scores, daily TPN volume intake and biochemical responses. Infants in the standardized TPN group received less sodium (P < 0.01) and no potassium on day 2 as required, more protein (P < 0.02) every day, and more calcium and phosphate (P < 0.02 from day 4).

CONCLUSION

There were no significant clinical and statistical differences in biochemical responses in newborn infants <33 weeks gestation who received standardized versus individualized TPN regimes during the first week of life. The economic cost of TPN provision using standardized TPN formulation was approximately 30% lower.

Juvenile neuronal ceroid lipofuscinosis

A case of juvenile neuronal ceroid lipofuscinosis (JNCL) diagnosed on the basis of clinical features, electrophysiologic studies and skin electron microscopy is reported. JNCL was suspected on the basis of characteristic symptoms including progressive loss of vision, seizures, mental retardation and motor disabilities. Diagnosis was confirmed by neurophysiological and biopsy studies. The disease is caused by 23 different mutations in a gene recently isolated on chromosome 16 p11.2-12.1. Although universally fatal, characterisation of mutations can help in prenatal diagnosis in future pregnancies.

Thermophilic fungi: their physiology and enzymes

Thermophilic fungi are a small assemblage in mycota that have a minimum temperature of growth at or above 20 degrees C and a maximum temperature of growth extending up to 60 to 62 degrees C. As the only representatives of eukaryotic organisms that can grow at temperatures above 45 degrees C, the thermophilic fungi are valuable experimental systems for investigations of mechanisms that allow growth at moderately high temperature yet limit their growth beyond 60 to 62 degrees C. Although widespread in terrestrial habitats, they have remained underexplored compared to thermophilic species of eubacteria and archaea. However, thermophilic fungi are potential sources of enzymes with scientific and commercial interests. This review, for the first time, compiles information on the physiology and enzymes of thermophilic fungi. Thermophilic fungi can be grown in minimal media with metabolic rates and growth yields comparable to those of mesophilic fungi. Studies of their growth kinetics, respiration, mixed-substrate utilization, nutrient uptake, and protein breakdown rate have provided some basic information not only on thermophilic fungi but also on filamentous fungi in general. Some species have the ability to grow at ambient temperatures if cultures are initiated with germinated spores or mycelial inoculum or if a nutritionally rich medium is used. Thermophilic fungi have a powerful ability to degrade polysaccharide constituents of biomass. The properties of their enzymes show differences not only among species but also among strains of the same species. Their extracellular enzymes display temperature optima for activity that are close to or above the optimum temperature for the growth of organism and, in general, are more heat stable than those of the mesophilic fungi. Some extracellular enzymes from thermophilic fungi are being produced commercially, and a few others have commercial prospects. Genes of thermophilic fungi encoding lipase, protease, xylanase, and cellulase have been cloned and overexpressed in heterologous fungi, and pure crystalline proteins have been obtained for elucidation of the mechanisms of their intrinsic thermostability and catalysis. By contrast, the thermal stability of the few intracellular enzymes that have been purified is comparable to or, in some cases, lower than that of enzymes from the mesophilic fungi. Although rigorous data are lacking, it appears that eukaryotic thermophily involves several mechanisms of stabilization of enzymes or optimization of their activity, with different mechanisms operating for different enzymes.

Senescent: a new Neurospora crassa nuclear gene mutant derived from nature exhibits mitochondrial abnormalities and a "death" phenotype

Fungi are capable of potentially unlimited growth. We resolved nuclear types from multinuclear mycelium of a phenotypically normal wild isolate of the fungus Neurospora intermedia by plating its uninucleate microconidia and obtained a strain which, unlike the "parent" strain, exhibited clonal senescence in subcultures. The mutant gene, senescent, was introgressed into N. crassa and mapped four map units to the right of the his-1 locus on linkage group VR. senescent is the first nuclear gene mutant of Neurospora derived from nature that shows the death phenotype. Death of the sen mutant occurred faster at 34 degrees C than at 22 or 26 degrees C. Measurements of oxygen uptake of conidia using respiratory inhibitors and the spectrophotometric analyses of mitochondrial cytochromes showed that in sen cultures grown at 34 degrees C, cytochromes b and aa(3) were present but cytochrome c was absent. By contrast at 26 degrees C, cytochromes b and c were present but cytochrome aa(3) was diminished in the late subcultures. This suggested that the sen mutation does not affect the potential to produce functional cytochromes. The deficiency of the respiratory chain cytochromes may not be the cause of death of the sen mutant because the cytochrome c and aa(3) mutants of N. crassa are capable of sustained growth whereas sen is not. Possible explanations for the observations are discussed.

A comparison of thermal characteristics and kinetic parameters of trehalases from a thermophilic and a mesophilic fungus

Trehalases from a thermophilic fungus Thermomyces lanuginosus (M(r) 145 kDa) and a mesophilic fungus Neurospora crassa (M(r) 437 kDa) were purified to compare their thermal characteristics and kinetic constants. Both trehalases were maximally active at 50 degrees C, had an acidic pH optimum and were glycoproteins (20% and 43%, w/w, carbohydrate content for T. lanuginosus and N. crassa, respectively). At their temperature optimum, their K(m) was similar (0.57 and 0.52 mM trehalose, for T. lanuginosus and N. crassa, respectively) but the V(max) of N. crassa enzyme was nine times higher than of T. lanuginosus enzyme. The catalytic efficiency, k(cat)/K(m), for N. crassa trehalase was one order of magnitude higher (6.2 x 10(6) M(-1) s(-1)) than of T. lanuginosus trehalase (4 x 10(5) M(-1) s(-1)). At their T(opt) (50 degrees C), trehalase from both sources exhibited similar thermostability (t(1/2)6 h). The energy of activation, E(a), for T. lanuginosus trehalase was 15.12 kcal mol(-1) and for N. crassa trehalase it was 9.62 kcal mol(-1). The activation energy for thermal inactivation for the N. crassa enzyme (92 kcal mol(-1)) was two-fold higher than for the T. lanuginosus enzyme (46 kcal mol(-1)). The present study shows that the trehalase of N. crassa is not only more stable but also a better catalyst than the T. lanuginosus enzyme.

An unusual pattern of invertase activity development in the thermophilic fungus Thermomyces lanuginosus

In the thermophilic fungus Thermomyces lanuginosus, invertase displays an unusual pattern of development: the induced activity begins to diminish even before any substantial quantity of sucrose has been utilized or an appreciable amount of biomass has been produced. Despite this pattern of invertase activity, neither the growth rate nor the final mycelial yield is affected adversely. T. lanuginosus invertase is a thiol protein and the enzyme is active when specific sulfhydryl group(s) is in the reduced state. Measurements of reduced coenzyme and glutathione pools in sucrose-growth mycelia excluded oxidative stress as the primary reason for the observed decline in invertase activity. Rather, this unusual pattern of invertase is considered to be due to its localization in the hyphal tips. At the early stage of growth, the number of hyphal tips per unit mass of mycelium is maximum, whereas at later times their numbers do not increase in proportion to the biomass. As a result invertase activity shows an apparent inverse relationship with biomass. The enzyme activity disappears when the inducing carbon source is consumed and growth is completed.

Microconidia of Neurospora crassa

Neurospora crassa produces two types of vegetative spores-relatively small numbers of uninucleate microconidia and very large numbers of multinucleate macroconidia (blastoconidia and arthroconidia). The microconidia can function either as spermatia (male gametes) or as asexual reproductive structures or both. In nature they probably function exclusively in fertilization of protoperithecia. The environmental conditions favoring their formation and the pattern of their development are quite distinct from those of macroconidia. Mutants of N. crassa have been isolated in which macroconidiation is selectively blocked without affecting microconidiation, showing that these two types of conidial differentiation involve distinct developmental pathways. Unlike microconidia of some related ascomycetes, those of Neurospora are capable of germination, providing viable uninucleate haploid cells which are desired in several types of investigations. A technique of selectively removing macroconidia from culture initiated on cellophane overlying agar medium allows pure microconidia to be obtained even from the wild-type strains of Neurospora. The conditional microcyclic strain, mcm, allows either macroconidia or microconidia to be obtained at will, depending on the conditions of culture. The new methods of obtaining pure microconidia from normal laboratory strains will make it quick and easy to purify heterokaryotic transformants following introduction of DNA into multinucleate protoplasts. Moreover, these methods allow the detection of genetic variability that remains hidden within an individual fungus and the estimation of the frequency of nuclear types in laboratory-constructed heterokaryons. The discovery, function, and development of microconidia are described and their research applications are discussed in this review.

Response of higher plants to lead contaminated environment

Lead concentration is increasing rapidly in the environment due to increased use of its sources by human society. Alarming concentrations of the metal have been reported in dust of densely populated urban areas and, water and land of various areas near the industrial waste disposals. Plants absorb lead and accumulation of the metal have been reported in roots, stems, leaves, root nodules and seeds etc. which increases with the increase in the exogenous lead level. Lead affects plant growth and productivity and the magnitude of the effects depend upon the plant species. Photosynthesis has been found to be one of the most sensitive plant processes and the effect of the metal is multifacial. Nitrate reduction is inhibited drastically in roots by the metal but in the leaves a differential effect is observed in various cultivars. Lead also inhibits nodulation, N-fixation and ammonium assimilation in the root nodules. It appears that the toxic effect of the metal is primarily at physiological level and provision of certain inorganic salts can antagonize the toxic effects to some extent. Further responses of plants to the metal depend on various endogenous, environmental and nutritional factors. Some plants are able to tolerate excess of Pb+2 by involving processes like exclusion, compartmentalization or synthesizing metal detoxifying peptides-the phytochelatins.

Incidence and risk factors of retinopathy of prematurity in a tertiary care newborn unit in New Delhi

BACKGROUND

Retinopathy of prematurity (RoP) has become more common in developed countries with an improvement in survival of very premature infants. Though previously rare, it is likely to emerge as a major problem in India because of improving outcome of 'at-risk' preterm infants.

METHODS

In a prospective study we estimated the incidence of RoP among at-risk neonates in a tertiary care unit. Infants with birth-weights of < 1500 g, gestation < 35 weeks and preterm neonates who required supplemental oxygen for > 24 hours were subjected to periodic ophthalmological evaluation for detection of RoP until full retinal vascularization occurred.

RESULTS

Sixty-six eligible infants completed the full protocol during the 15-month study period. The incidence of RoP was 20% in the cohort and 27% among the very low birth-weight neonates. The incidence of threshold RoP was 7% in the cohort. The occurrence of RoP was inversely related to the gestation and birth-weight. RoP typically developed at the post-conceptional age of 32-35 weeks. Blood transfusion and clinical sepsis emerged as independent risk factors of RoP on step-wise logistic regression analysis. Cryotherapy undertaken in 5 cases (9 eyes) led to amelioration of the changes of RoP.

CONCLUSION

The incidence of RoP in our neonates was lower than that reported from other centres. Blood transfusion and clinical sepsis are risk factors for RoP in our newborn infants.

A Demonstration of the Role of het Genes in Heterokaryon Formation in Neurospora under Simulated Field Conditions

An experimental system was developed for assessing the role of het genes in heterokaryon formation in Neurospora in nature. Burned sugar cane segments planted in soil were infected using a mixture of mutant ascospores of two genotypes. Neurospora ramified in the cane and erupted as distinct pustules of conidia. When ascospores carried identical het alleles, the (macro) conidial pustules which formed were heterokaryotic. On the other hand, when ascospores carried dissimilar het alleles, the pustules were homokaryotic. These results showed that stable heterokaryons between compatible strains can form in nature. When two strains are growing together on a natural substrate, heterozygosity at het loci serves to maintain their individuality.

A novel invertase from a thermophilic fungus Thermomyces lanuginosus: its requirement of thiol and protein for activation

Unlike the invertases from the mesophilic fungi and yeasts, invertase from a thermophilic fungi, Thermomyces lanuginosus, was unusually unstable both in vivo and in vitro. The following observations suggested that the unstable nature of the enzyme activity in the cell-free extracts was due to the oxidation of the cysteine residue(s) in the enzyme molecule: (a) the addition of dithiothreitol or reduced glutathione stabilized invertase activity during storage of the extracts and also revived enzyme activity in the extracts which had become inactive with time; (b) N-ethylmaleimide, iodoacetamide, oxidized glutathione, cystine, or oxidized coenzyme A-inactivated invertase; (c) invertase activity was low when the ratio reduced/oxidized glutathione was lower and high when this ratio was higher, suggesting regulation of the enzyme by thiol/disulfide exchange reaction. In contrast to the activation of invertase by the thiol compounds and its inactivation by the disulfides in the cell-free extracts, the purified enzyme did not respond to these compounds. Following its inactivation, the purified enzyme required a helper protein in addition to dithiothreitol for maximal activation. A cellular protein was identified that promoted activation of invertase by dithiothreitol and it was called "PRIA" for the protein which helps in restoring invertase activity. The revival of enzyme activity was due to the conversion of the inactive invertase molecules into an active form. A model is presented to explain the modulation of invertase activity by the thiol compounds and the disulfides, both in the crude cell-free extracts and in the purified preparations. The requirement of free sulfhydryl group(s) for the enzyme activity and, furthermore, the reciprocal effects of the thiols and the disulfides on invertase activity have not been reported for invertase from any other source. The finding of a novel invertase which shows a distinct mode of regulation demonstrates the diversity in an enzyme that has figured prominently in the development of biochemistry.

Microcycle conidiation and its genetic basis in Neurospora crassa

Some wild isolates of Neurospora show microcycle conidiation in liquid culture under continuous agitation. Macroconidia from agar-grown mycelial cultures germinated in liquid and the germlings spontaneously produced conidia with no intervening mycelial phase. Three types of microcycle conidiation were seen among progeny of N. crassa Vickramam A x N. crassa a wild-type: (1) multinucleate blastoconidia produced by apical budding and septation, (2) multinucleate arthroconidia produced by holothallic septation and disarticulation of cells, and (3) uninucleate microconidia produced directly from conidiogenous cells of the germlings. Two genes were identified which control specific patterns of microcycle conidiogenesis. A single gene mcb in linkage group VR near al-3 (3.2% recombination) controls blastoconidiation. This gene is epistatic to gene mcm located in linkage group IIL, very near ro-7 (1.4%). mcm controls both microconidiation and arthroconidiation depending on temperature. Strains of genotype mcm produce microconidia almost exclusively at 18-22 degrees C, but arthroconidia with few or no microconidia at 30 degrees C. Because they result in rapid and synchronized conidiation in liquid culture, the two genes should be useful for studies of developmental gene regulation. mcm makes it possible to obtain large quantities of pure microconidia rapidly for experimentation.

Developmental electrophysiologic effects of propafenone and 5-hydroxypropafenone on the canine cardiac Purkinje fiber

Standard microelectrode techniques were used to investigate the in vitro developmental electrophysiologic effects of propafenone and 5-hydroxypropafenone on the adult and neonatal canine Purkinje fiber. The tonic and frequency-dependent depressant effects of these compounds on Vmax and amplitude were similar in both age groups. However, the ability of these compounds to shorten repolarization parameters was more pronounced in the adult. The extent of reduction of abnormal automaticity produced by propafenone was greater in the neonate compared to the adult, and 5-hydroxypropafenone significantly reduced automaticity only in the neonate. The sensitivity of neonatal abnormal automaticity to the effects of these compounds may prove to be important if the use of these agents is to be expanded into the realm of therapy for pediatric automatic rhythms.

Potentiation of immune response against malaria in immunocompromised mice through glucan as an immunoadjuvant

Untreated mice were fully immunocompetent but their treatment with various immunosuppressors rendered them immunocompromised with respect to one or the other or both limbs of immunity. Both, humoral immune response or cell mediated immune response suppressed mice were only partially protected against the challenge with Plasmodium berghei following their immunization. Hydrocortisone treated mice, in which both types of immune responses were suppressed, were not protected against the challenge with P. berghei following their immunization. In contrast, untreated immunized mice, were fully protected against the challenge with P. berghei. The results suggest that glucan potentiated both limbs of immunity and both were involved in the host defence against malaria.

Immunoprotection by beta-1,3 glucan antigen combination in Plasmodium berghei infection in mice

In an attempt to protect mice against experimental infection with P. berghei, mice were immunized against soluble extract of P. berghei in combination with beta-1,3 glucan or FCA and also independently. Mice immunized against P. berghei antigen-glucan developed well defined cell mediated and humoral immune responses, while mice injected with antigen FCA or antigen alone developed only an antibody response. Antigen-glucan immunization afforded a high degree of immune protection to the host against the challenge with live parasites.

Simultaneous utilization of glucose and sucrose by thermophilic fungi

The utilization of mixtures of glucose and sucrose at nonlimiting concentrations was studied in batch cultures of two common thermophilic fungi, Thermomyces lanuginosus and Penicilium duponti. The sucrose-utilizing enzymes (sucrose permease and invertase) in both fungi were inducible. Both sugars were used concurrently, regardless of their relative proportion in the mixture. At the optimal growth temperature (50 degrees C), T. lanuginosus utilized sucrose earlier than it did glucose, but at a suboptimal growth temperature (30 degrees C) the two sugars were utilized at nearly comparable rates. The coutilization of the two sugars was most likely possible because (i) invertase was insensitive to catabolite repression by glucose, (ii) the activity and affinity of the glucose transport system were lowered when sucrose was included in the growth medium, and (iii) the activity of the glucose uptake system was also subject to repression by high concentrations of glucose itself. The concurrent utilization of the available carbon sources by thermophilic fungi might be an adaptive strategy for opportunistic growth in nature under conditions of low nutrient availability and thermal fluctuations in the environment.

Sporotrichum thermophile Growth, Cellulose Degradation, and Cellulase Activity

The activity of components of the extracellular cellulase system of the thermophilic fungus Sporotrichum thermophile showed appreciable differences between strains; β-glucosidase (EC 3.2.1.21) was the most variable component. Although its endoglucanase (EC 3.2.1.4) and exoglucanase (EC 3.2.1.91) activities were markedly lower, S. thermophile degraded cellulose faster than Trichoderma reesei . The production of β-glucosidase lagged behind that of endoglucanase and exoglucanase. The latter activities were produced during active growth. When growth was inhibited by cycloheximide treatment, the hydrolysis of cellulose was lower than in the control in spite of the presence of both endoglucanase and exoglucanase activities in the culture medium. Degradation of cellulose was a growth-associated process, with cellulase preparations hydrolyzing cellulose only to a limited extent. The growth rate and cell density of S. thermophile were similar in media containing cellulose or glucose. A distinctive feature of fungal development in media incorporating cellulose or lactose (inducers of cellulase activity) was the rapid differentiation of reproductive units and autolysis of hyphal cells to liberate propagules which were capable of renewing growth immediately.

Thrombosis of Björk-Shiley valve prostheses. Evaluation by cineradiography

Cineradiography is the most accurate and rapid method in evaluation of the function of Björk-Shiley prosthetic valves manufactured after late 1975 and which incorporate a tantalum foil hoop into the disc. This helps in demonstration of the disc and in the calculation of the opening angle of the disc. In the present series 8 cases with valve dysfunction have been correctly diagnosed by conventional cineradiography, 7 in the mitral and one in the aortic position. In all 8 cases and also in the group of 300 postoperative cases having no symptoms, the opening angle has been measured by the method described by Venkataraman et coll. in 1980. It is recommended that in accordance with the suggestions of these authors, the opening angle should be established for each patient in the immediate postoperative period in order to provide a basis for possible future examinations.

Trehalose Toxicity in Cuscuta reflexa: Cell Wall Synthesis Is Inhibited upon Trehalose Feeding

alpha,alpha-Trehalose induced a rapid blackening of the terminal 2.5-centimeter region of excised Cuscuta reflexa Roxb. vine. The incorporation of radioactivity from [(14)C]glucose into alkali-insoluble fraction of shoot tip was markedly inhibited by 12 hours of trehalose feeding to an excised vine. This inhibition was confined to the apical segment of the vine in which cell elongation occurred. The rate of blackening of shoot tip explants was hastened by the addition of gibberellic acid A(3), which promoted elongation growth of isolated Cuscuta shoot tips. The symptom of trehalose toxicity was duplicated by 2-deoxyglucose, which has been shown to be a potent inhibitor of cell wall synthesis in yeast. The observations suggest that trehalose interferes with the synthesis of cell wall polysaccharides, the chief component of which was presumed to be cellulose.

Trehalose Toxicity in Cuscuta reflexa: SUCROSE CONTENT DECREASES IN SHOOT TIPS UPON TREHALOSE FEEDING

Trehalose, an alpha,alpha-diglucoside, induced a rapid blackening and death of shoot tips of Cuscuta reflexa (dodder) cultured in vitro. The onset of toxic symptom was delayed if any of the several sugars which support the in vitro growth of Cuscuta was supplied with trehalose. The rate of trehalose uptake or its accumulation in the tissue was not affected by sugar cofeeding. The levels of total and reducing sugars declined appreciably in the trehalose-fed shoot tip explants compared to control tissue cultured in absence of a carbon source. This was not due to an increased rate of respiration of the trehalose-treated tissue. In shoot tips cultured in presence of both trehalose and sucrose, the decline in total and reducing sugars was curtailed. There was a marked fall in the level of sucrose; and invertase activity was higher in trehalose-fed shoot tips. The incorporation of label from [(14)C]glucose into sucrose in the shoot tip explant was reduced as early as 12 h of trehalose feeding. The results suggest that increased utilization of sucrose as well as an inhibition of its synthesis contribute to the drastic fall in the sucrose content upon trehalose feeding.

Trehalose Toxicity in Cuscuta reflexa: CORRELATION WITH LOW TREHALASE ACTIVITY

A toxic effect of alpha,alpha-trehalose in an angiospermic plant, Cuscuta reflexa (dodder), is described. This disaccharide and its analogs, 2-aminotrehalose and 4-aminotrehalose, induced a rapid blackening of the terminal region of the vine which is involved in elongation growth. From the results of in vitro growth of several angiospermic plants and determination of trehalase activity in them, it is concluded that the toxic effect of trehalose in Cuscuta is because of the very low trehalase activity in the vine. As a result, trehalose accumulates in the vine and interferes with some process closely associated with growth. The growth potential of Lemna (a duckweed) in a medium containing trehalose as the carbon source was irreversibly lost upon addition of trehalosamine, an inhibitor of trehalase activity. It is concluded that, if allowed to accumulate within the tissue, trehalose may be potentially toxic or inhibitory to higher plants in general. The presence of trehalase activity in plants, where its substrate has not been found to occur, is envisaged to relieve the plant from the toxic effects of trehalose which it may encounter in soil or during association with fungi or insects.

Interaction of Gibberellic Acid and Indole-3-acetic Acid in the Growth of Excised Cuscuta Shoot Tips in Vitro

Gibberellic acid (GA(3)) induced a marked elongation of 2.5-centimeter shoot tips of Cuscuta chinensis Lamk. cultured in vitro. In terms of the absolute amount of elongation, this growth may be the largest reported for an isolated plant system. The response to hormone was dependent on an exogenous carbohydrate supply. The hormone-stimulated growth was due to both cell division and cell elongation. The growth response progressively decreased if GA(3) was given at increasingly later times after culturing, but the decreased growth response could be restored by the application of indole-3-acetic acid (IAA) to the apex. Explants deprived of GA(3) gradually lost their ability to transport IAA basipetally, but this ability was also restored by auxin application. The observations are explained on the basis that: (a) the growth of Cuscuta shoot tip in vitro requires, at least, both an auxin and a gibberellin; and (b) in the absence of gibberellin the cultured shoot tip explants lose the ability to produce and/or transport auxin.

Effect of temperature on respiration of a mesophilic and a thermophilic fungus

The respiratory rates of mycelia of the mesophilic fungus, Aspergillus niger, and the thermophilic fungus, Thermomyces lanuginosus, were comparable at their respective temperature optima for growth. The respiratory rate of A. niger was independent of changes in temperature between 15 and 40 C. The respiratory rate of T. lanuginosus increased with increase in temperature between 25 and 55 C.