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1.
PLoS One ; 19(6): e0305097, 2024.
Article in English | MEDLINE | ID: mdl-38857213

ABSTRACT

Understanding of soil phosphorus (P) transformation is crucial to minimize its edge-of-field loss associated with ecosystem disservices. A sequential chemical extraction procedure was used to assess the impact (42 years) of organic and chemical fertilizations on soil P partition and distribution under subtropical rice based cropping systems. Experimental treatments were control, N, NP, NK, NS, NZn, NPK, NSZn, NPKSZn, and N+FYM (farmyard manure). Composite soils were collected from 0-5, 20-25 and 40-45 cm depths, extracted, and analyzed for soluble P, NaHCO3-P (inorganic and organic), NaOH-P (inorganic and organic), acid soluble (H2SO4), and residual P fractions. The NPKSZn significantly increased the concentration of soil inorganic P compared to other treatments. When FYM was applied together with N fertilizer, the organic P concentration increased, which was statistically identical to NPKSZn and NPK treatments. While the labile (NaHCO3-Pi, NaOH-Po), residual, and total P concentrations were stratified at 0-5 cm depth, the concentration of NaHCO3-Po, NaOH-Pi, and acidic P fractions increased with soil depth. The soluble, NaHCO3 (Pi and Po), NaOH-Pi and NaOH-Po, acidic, and residual P fractions constituted about 0.4, 6.6, 1.7, 21.3, 37.7, and 8.3%, respectively, of the total P. A higher concentration of the labile P at the surface soil indicated that the impact of chemical fertilization stratified the available P for plant uptake or susceptible to edge-of-field loss. The NPKSZn and N+FYM both had higher NaHCO3-Po and NaOH-Po concentrations within 40-45 cm and 0-25 cm depths, suggesting that N+FYM could promote the transformation of non-labile P into labile P pool, by reducing P fixation by soil and transport them at 20-45 cm depth. It is concluded that long-term fertilization increased the concentration of P pools especially labile P by saturating the soil adsorption sites especially in surface soil.


Subject(s)
Fertilizers , Oryza , Phosphorus , Soil , Oryza/growth & development , Oryza/chemistry , Phosphorus/analysis , Soil/chemistry , Fertilizers/analysis , Agriculture/methods , Crops, Agricultural/growth & development
2.
Mymensingh Med J ; 33(2): 440-445, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38557523

ABSTRACT

The incidence of first trimester pregnancy loss is around 10.0-20.0% of registered pregnancies. Manual vacuum aspiration is a safe, effective and acceptable option of treatment for patients diagnosed with first trimester pregnancy loss. Main disadvantage of MVA is the pain caused by manipulation of the cervix, the uterine suction and the cervical dilatation. This study showed the way how the pain and discomfort might be reduced. This was a cross-sectional comparative study was conducted at the obstetrics and Gynecological Department of Sadar hospital, Manikganj, Bangladesh from January 2017 to December 2017. All the consecutive women admitted and diagnosed as incomplete abortion, missed abortion and anembryonic pregnancy (blighted ovum) were included in this study. Sampling technique was purposive sampling. The objective of this study was to compare the effectiveness of paracervical block anesthesia with non-steroidal anti inflammatory drug (NSAID) for relief of pain during the manual vacuum aspiration procedure for the treatment of first trimester pregnancy loss. Total 120 cases were included in this study. Assigned study population were divided into two groups like Group A and Group B. 60 of the study population were included in Group A who were given paracervical block anesthesia 3 minutes before the procedure. Another 60 study population was included in Group B who was given diclofenac 75mg intramuscular injection, 30 minutes before the procedure. Both intraoperative and postoperative pain level was evaluated by using visual analog scale ranged from (0-10 points) 30 minutes after the procedure. At the same time the satisfaction level of the study population were measured by 5 points lickert scale. Regarding clinical profile of the study population it showed no significant difference in case of mean age, mean gestational age and mean duration of the procedure between two groups. The mean intraoperative pain score in Group A was 4.0±1.3, in Group B it was 5.4±1.5 (p=0.001) which was significant. So it showed that paracervical block anesthesia significantly reduced the pain in relation to diclofenac 75mg intramuscular injection. Mean postoperative pain level 30 minutes after procedure in Group A was 2.2±0.4 and in Group B was 2.4±0.4 (p=0.343), where post-operative pain is lower in Group A than Group B. Though this difference is not statistically significant (p=0.343). In Group A 73.0% (n=44) and in Group B 43.0% (n=26) study population were agreed that the procedure was easy. Most common adverse effect was epigastric pain which was 1.7% (n=1) in Group A and 10.0% (n=7) in Group B. Paracervical block significantly reduces intraoperative pain during Manual Vacuum Aspiration (MVA) procedure in the treatment of first trimester pregnancy loss in comparison to intramuscular injection of diclofenac. In conclusion it might be mentioned that regarding paracervical block anesthesia, efficacy is higher and side effects are less. Moreover paracervical block anesthesia is cost effective.


Subject(s)
Anesthesia, Obstetrical , Vacuum Curettage , Pregnancy , Humans , Female , Vacuum Curettage/adverse effects , Vacuum Curettage/methods , Diclofenac/therapeutic use , Anesthesia, Obstetrical/adverse effects , Anesthesia, Obstetrical/methods , Cross-Sectional Studies , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Pregnancy Trimester, First , Pain, Postoperative/drug therapy , Pain, Postoperative/prevention & control
3.
Mymensingh Med J ; 33(2): 526-532, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38557536

ABSTRACT

Meconium-stained amniotic fluid is the passage of meconium by a fetus in utero during the antenatal period or in labour. It has for long been considered to be a bad predictor of fetal distress and meconium aspiration syndrome (MAS). The objective of this study was to find out the fetal outcome of MSAF and clear amniotic fluid. This cross- sectional comparative study was carried out in Upazilla Health Complex, Palash, Narshingdi from July 2016 to June 2017. A total of 100 pregnant women among them 50 women with MSAF and 50 women with clear liquor were studied to see the record of ANC, mode of delivery and fetal outcome by APGAR score. Study showed that among MSAF group 76.0% (n=38) had irregular ANC and 24.0% (n=12) had regular ANC whereas in clear liquor 86.0% (n=43) had regular ANC 14.0% had irregular ANC. Among MSAF (50 cases) thick meconium was in 20 cases (40.0%) and thin meconium was in 30 cases (60.0%). Regarding mode of delivery 52.0% (n=26) MSAF cases had instrumental delivery and Caesarean section compared to 24.0% (n=12) in clear liquor group. Regarding thick MSAF among 40.0% (n=20), (n=14) had low APGAR score and (n=6) had normal score at one minute and (n=9) low APGAR score and (n=11) normal score at five minutes. In clear liquor, among 100.0% (n=50), 20.0% (n=10) had low APGAR score and 80.0% (n=40) had normal score at one-minute and at five minutes 8.0% (n=4) had low APGAR score and 92.0% (n=46) had normal score. Among MSAF 26.0% (n=13) were admitted to SCBU compare to 12.0% (n=6) in clear liquor group. The mean SCBU stay was 3.1 days in MSAF whereas 1.2 days in clear liquor. Among MSAF babies 4.0% (n=2) had MAS compared to no MAS in clear liquor group. Regarding Survivalist 92.0% (n=46) were alive in MSAF whereas 100.0% all (n=50) were alive in clear liquor group.


Subject(s)
Meconium Aspiration Syndrome , Meconium , Female , Infant, Newborn , Humans , Pregnancy , Amniotic Fluid , Cesarean Section , Staining and Labeling
4.
Nat Commun ; 6: 6722, 2015 Apr 10.
Article in English | MEDLINE | ID: mdl-25857284

ABSTRACT

An imbalance between neutrophil-derived proteases and extracellular inhibitors is widely regarded as an important pathogenic mechanism for lung injury. Despite intense efforts over the last three decades, attempts to develop small-molecule inhibitors for neutrophil elastase have failed in the clinic. Here we discover an intrinsic self-cleaving property of mouse neutrophil elastase that interferes with the action of elastase inhibitors. We show that conversion of the single-chain (sc) into a two-chain (tc) neutrophil elastase by self-cleavage near its S1 pocket altered substrate activity and impaired both inhibition by endogenous α-1-antitrypsin and synthetic small molecules. Our data indicate that autoconversion of neutrophil elastase decreases the inhibitory efficacy of natural α-1-antitrypsin and small-molecule inhibitors, while retaining its pathological potential in an experimental mouse model. The so-far overlooked occurrence and properties of a naturally occurring tc-form of neutrophil elastase necessitates the redesign of small-molecule inhibitors that target the sc-form as well as the tc-form of neutrophil elastase.


Subject(s)
Leukocyte Elastase/metabolism , Lung/drug effects , Neutrophils/drug effects , Peptides/metabolism , Proteinase Inhibitory Proteins, Secretory/pharmacology , Pulmonary Emphysema/drug therapy , Amino Acid Sequence , Animals , Catalytic Domain , Cytokines/biosynthesis , Female , Gene Expression , HEK293 Cells , Humans , Leukocyte Elastase/administration & dosage , Leukocyte Elastase/antagonists & inhibitors , Leukocyte Elastase/chemistry , Lung/enzymology , Lung/pathology , Macrophages/drug effects , Macrophages/pathology , Mice , Mice, Inbred C57BL , Molecular Sequence Data , Neutrophils/enzymology , Neutrophils/pathology , Peptides/administration & dosage , Peptides/antagonists & inhibitors , Peptides/chemistry , Proteolysis , Pulmonary Emphysema/chemically induced , Pulmonary Emphysema/enzymology , Pulmonary Emphysema/pathology , Recombinant Proteins/administration & dosage , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid , Small Molecule Libraries/pharmacology , alpha 1-Antitrypsin/pharmacology
5.
Water Sci Technol ; 71(4): 529-37, 2015.
Article in English | MEDLINE | ID: mdl-25746644

ABSTRACT

The process of developing an integrated water demand model integrating end uses of water has been presented. The model estimates and forecasts average daily water demand based on the end-use pattern and trend of residential water consumption, daily rainfall and temperature, water restrictions and water conservation programmes. The end-use model uses the latest end-use data set collected from Yarra Valley Water, Australia. A computer interface has also been developed using hypertext markup language and hypertext pre-processor. The developed model can be used by water authorities and water resource planners in forecasting water demand and by household owners in determining household water consumption.


Subject(s)
Models, Theoretical , Water Resources , Water Supply , Water , Australia , Environment
6.
Mymensingh Med J ; 20(2): 192-6, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21522086

ABSTRACT

To see accuracy of ultrasound scan to detect patent processus vaginalis in padiatric patient. We investigated the presence of contralateral patent processus vaginalis (CPPV) by Ultrasound scan (US) in children with clinically diagnosed unilateral inguinal hernia. Thirty patents (17 boys and 13 Girls) with unilateral inguinal hernia underwent US examination using a 7.5 MHZ transducer. If a CPPV was visible as a hydrocele (inflow of peritoneal fluid) in to a processus vaginalis on straining, then US scanning was performed while the patient was at rest and while inducing straining by standing, coughing and or crying. A groin with hydrocele in the inguinal canal on straining was diagnosed as a CPPV and was explored bilaterally through surgery. The US findings were compared with surgical results. In 30 patients, 12 cases were diagnosed by US as patients with a CPPV, these patients underwent bilateral surgery. Eleven of 12 Cases were confirmed surgically as CPPV. From the findings of the present study it could be concluded that a PPV could be correctly detected by US in pediatric patients with the accuracy of 91.67%. US is a non invasive and accurate method for evaluating the presence of a PPV. Preoperative diagnosis of CPPV is important to remove the need for a second operation with patients presenting with unilateral inguinal hernia.


Subject(s)
Hernia, Inguinal/diagnostic imaging , Peritoneal Diseases/diagnostic imaging , Testicular Hydrocele/diagnostic imaging , Child , Child, Preschool , Female , Humans , Male , Sensitivity and Specificity , Ultrasonography
7.
Mymensingh Med J ; 17(1): 98-101, 2008 Jan.
Article in English | MEDLINE | ID: mdl-18285744

ABSTRACT

A 35 years old male living in Jamalpur district of Bangladesh working as a shopkeeper presented with dyspnea, fatigue, occasional fever and cough for two years. He did not give any history of hemoptysis or weight loss. He was smoker and non-alcoholic. He had a soft systolic murmur over pulmonary area and wide fixed splitting of the second heart sound. An Atrial septal defect (ASD) was detected by echocardiography. The patient had high circulating eosinophil count and Complement Fixation Test for filarial antibody revealed positive result. Moreover the patient's response to drug Diethylcarbamazime indicated suspected tropical pulmonary eosinophilia with Atrial Septal Defect.


Subject(s)
Heart Septal Defects, Atrial/complications , Heart Septal Defects, Atrial/surgery , Pulmonary Eosinophilia/complications , Adult , Heart Septal Defects, Atrial/diagnosis , Humans , Male , Pulmonary Eosinophilia/diagnosis , Pulmonary Eosinophilia/surgery
8.
EMBO J ; 20(16): 4408-13, 2001 Aug 15.
Article in English | MEDLINE | ID: mdl-11500368

ABSTRACT

The major facilitator superfamily (MFS) represents the largest collection of evolutionarily related members within the class of membrane 'carrier' proteins. OxlT, a representative example of the MFS, is an oxalate-transporting membrane protein in Oxalobacter formigenes. From an electron crystallographic analysis of two-dimensional crystals of OxlT, we have determined the projection structure of this membrane transporter. The projection map at 6 A resolution indicates the presence of 12 transmembrane helices in each monomer of OxlT, with one set of six helices related to the other set by an approximate internal two-fold axis. The projection map reveals the existence of a central cavity, which we propose to be part of the pathway of oxalate transport. By combining information from the projection map with related biochemical data, we present probable models for the architectural arrangement of transmembrane helices in this protein superfamily.


Subject(s)
Bacterial Proteins/chemistry , Carrier Proteins/chemistry , Membrane Proteins/chemistry , Membrane Transport Proteins , Amino Acid Sequence , Bacterial Proteins/genetics , Carrier Proteins/genetics , Membrane Proteins/genetics , Molecular Sequence Data , Oxalobacter formigenes/chemistry , Protein Structure, Secondary , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics
9.
J Bacteriol ; 183(3): 1110-2, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11208813

ABSTRACT

Staphylococcus lugdunensis and Corynebacterium amycolatum each have a Na(+)/glutamine cotransporter that displays an ordered reaction sequence at the extracellular surface, with sodium binding (K(m) of 6.5 mM) before glutamine (K(m) of 50 microM). Asparagine is low-affinity substrate (K(m) approximately 1 mM) for each system.


Subject(s)
Amino Acid Transport System X-AG , Carrier Proteins/metabolism , Corynebacterium/metabolism , Glutamates/metabolism , Sodium/metabolism , Staphylococcus/metabolism , Symporters , Biological Transport , Energy Metabolism , Glutamate Plasma Membrane Transport Proteins , Skin/microbiology , Sweat/metabolism
10.
J Biol Chem ; 276(12): 8753-60, 2001 Mar 23.
Article in English | MEDLINE | ID: mdl-11113128

ABSTRACT

OxlT, the oxalate:formate antiporter of Oxalobacter formigenes, has a lone charged residue, lysine 355 (Lys-355), at the center of transmembrane helix 11 (TM11). Because Lys-355 is the only charged residue in the hydrophobic sector, we tested the hypothesis that lysine 355 contributes to the binding site for the anionic substrate, oxalate. This idea was supported by mutational analysis, which showed that of five variants studied (Lys-355 --> Cys, Gly, Gln, Arg, or Thr), residual function was found for only the K355R derivative, in which catalytic efficiency had fallen 2,600-fold. Further insight came from a study of TM11 single-cysteine mutants, using the impermeant, thiol-specific reagents, carboxyethyl methanethiosulfonate and ethyltrimethylammonium methanethiosulfonate. Of the five reactive positions identified in TM11, four were at the cytoplasmic or periplasmic ends of TM11 (S344C and A345C, and G366C and A370C, respectively), whereas the fifth was at the center of the helix (S359C). Added study with carboxyethyl methanethiosulfonate and ethylsulfonate methylthiosulfonate showed that the attack on S359C could be blocked by the presence of the substrate, oxalate, and that protection could be predicted quantitatively by a kinetic model in which S359C is accessible only in the unliganded form of OxlT. Parallel study showed that the proteoliposomes used in such work contained OxlT of right side-out and inside-out orientations in about equal amounts. Accordingly, full inhibition of S359C by the impermeable methanethiosulfonate-linked probes must reflect an approach from both the cytosolic and periplasmic surfaces of the protein. This, coupled with the finding of substrate protection, leads us to conclude that S359C lies on the translocation pathway through OxlT. Since position 359 and 355 lie on the same helical face, we suggest that Lys-355 also lies on the translocation pathway, consistent with the idea that the essential nature of Lys-355 reflects its role in binding the anionic substrate, oxalate.


Subject(s)
Bacterial Proteins , Carrier Proteins , Membrane Proteins/metabolism , Membrane Transport Proteins , Proteobacteria/metabolism , Biological Transport , Indicators and Reagents/chemistry , Membrane Proteins/chemistry , Membrane Proteins/genetics , Mutagenesis, Site-Directed , Protein Conformation , Structure-Activity Relationship
11.
J Bacteriol ; 179(5): 1805-8, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9045844

ABSTRACT

Previously, we cloned and sequenced a DNA fragment from Vibrio parahaemolyticus and found four open reading frames (ORFs). Here, we clearly demonstrate that one of the ORFs, ORF1, is the gene (sglS) encoding a Na+/glucose symporter (SglS). We characterize the Na+/glucose symporter produced in Escherichia coli mutant (JM1100) cells which lack original glucose transport activity and galactose transport activity. We also show that phlorizin, a potent inhibitor of the SGLT1 Na+/glucose symporter of animal cells, inhibited glucose transport, but not galactose transport, via the SglS system.


Subject(s)
Glucose/metabolism , Monosaccharide Transport Proteins/chemistry , Monosaccharide Transport Proteins/metabolism , Sodium/metabolism , Vibrio parahaemolyticus/chemistry , Bacterial Proteins , Biological Transport , Escherichia coli/genetics , Escherichia coli/metabolism , Galactose/metabolism , Genes, Bacterial , Kinetics , Monosaccharide Transport Proteins/genetics , Open Reading Frames , Phlorhizin/pharmacology , Sequence Homology, Amino Acid , Sodium-Glucose Transport Proteins , Substrate Specificity , Vibrio parahaemolyticus/genetics , Vibrio parahaemolyticus/metabolism
12.
Biochim Biophys Acta ; 1281(1): 1-4, 1996 May 22.
Article in English | MEDLINE | ID: mdl-8652595

ABSTRACT

The nucleotide sequence of an approximately 6 kbp segment of chromosomal DNA of Vibrio parahaemolyticus was determined. The nucleotide sequence revealed four open reading frames (ORFs) in this region. Hydropathy profiles of the deduced amino acid sequence of the ORFs indicate that ORF1 encodes a hydrophobic polypeptide with typical characteristics of a membrane transport protein. All other ORFs encode hydrophilic polypeptides. ORF1 showed significant amino acid sequence similarity to proteins of the SGLT (Na+/glucose symporter) family, and the amino acid sequence of ORF4 showed very high similarity to several bacterial transcriptional repressor proteins (GalR-LacI family). We observed elevated glucose transport activity in cells harboring a plasmid carrying the DNA region corresponding to ORF1, and the glucose transport was greatly stimulated by Na+. Thus, we believe that ORF1 encodes a Na+/glucose symporter.


Subject(s)
Monosaccharide Transport Proteins/genetics , Vibrio parahaemolyticus/genetics , Amino Acid Sequence , Bacterial Proteins , Base Sequence , Biological Transport , DNA, Bacterial/chemistry , Escherichia coli/genetics , Gene Expression , Glucose/metabolism , Humans , Molecular Sequence Data , Monosaccharide Transport Proteins/chemistry , Open Reading Frames , Plasmids , Sequence Analysis, DNA , Sequence Homology , Sodium/pharmacology , Sodium-Glucose Transport Proteins , Transformation, Bacterial
13.
Biochim Biophys Acta ; 1279(2): 149-56, 1996 Mar 13.
Article in English | MEDLINE | ID: mdl-8603081

ABSTRACT

We have investigated galactose transport in a mutant strain of Vibrio parahaemolyticus that lacks a glucose-PTS (phosphoenolpyruvate:carbohydrate phosphotransferase system) and a trehalose-PTS. Cells of the V. parahaemolyticus actively transported D-galactose and Na+ greatly stimulated the transport. Maximum stimulation of D-galactose transport activity was observed at 10mM NaCl, and Na+ could be replaced with Li+. Addition of galactose to the cell suspension under anaerobic conditions elicited Na+ uptake. Therefore, we conclude that this organism accomplishes galactose transport by a Na+/solute symport mechanism. Judging from inhibition results, D-galactose, D-glucose and to a lesser extent alpha-D-fucose are substrates of this transport system. The Na+/galactose symport system exhibited a high affinity for D-galactose (Km: 40 microM) and showed a relatively lower affinity for D-glucose (Km: 420 microM), but the maximum velocities for galactose and glucose transport were almost same (about 52 nmol/min per mg protein). The Na+/D-galactose symport system was induced by either D-galactose or alpha-D-fucose, and repressed by D-glucose.


Subject(s)
Galactose/metabolism , Glucose/metabolism , Monosaccharide Transport Proteins/metabolism , Sodium/metabolism , Vibrio parahaemolyticus/metabolism , Biological Transport/drug effects , Ion Transport , Kinetics , Salts/pharmacology , Sodium Chloride/pharmacology , Substrate Specificity , Vibrio parahaemolyticus/growth & development
14.
J Bacteriol ; 176(23): 7378-82, 1994 Dec.
Article in English | MEDLINE | ID: mdl-7961512

ABSTRACT

Cells of a glucose-PTS (phosphoenolpyruvate:carbohydrate phosphotransferase system)-negative mutant of Vibrio parahaemolyticus transport D-glucose in the presence of Na+. Maximum stimulation of D-glucose transport was observed at 40 mM NaCl, and Na+ could be replaced partially with Li+. Addition of D-glucose to the cell suspension under anaerobic conditions elicited Na+ uptake. Thus, we conclude that glucose is transported by a Na+/glucose symport mechanism. Calculated Vmax and Km values for the Na(+)-dependent D-glucose transport were 15 nmol/min/mg of protein and 0.57 mM, respectively, when NaCl was added at 40 mM. Na+ lowered the Km value without affecting the Vmax value. D-Glucose was the best substrate for this transport system, followed by galactose, alpha-D-fucose, and methyl-alpha-glucoside, judging from the inhibition pattern of the glucose transport. D-Glucose itself partly repressed the transport system when cells were grown in its presence.


Subject(s)
Carrier Proteins/metabolism , Glucose/metabolism , Sodium/metabolism , Vibrio parahaemolyticus/metabolism , Biological Transport , Glucosides/metabolism , Lithium/metabolism , Monosaccharides/metabolism , Phosphoenolpyruvate Sugar Phosphotransferase System/genetics , Potassium/metabolism
15.
Trans R Soc Trop Med Hyg ; 87(4): 428-32, 1993.
Article in English | MEDLINE | ID: mdl-8249073

ABSTRACT

An enzyme-linked immunosorbent assay (ELISA) to detect antigens of Giardia duodenalis in faeces was evaluated as a diagnostic tool by testing faecal samples collected during a cohort study of 229 infants living in an urban slum in Dhaka, Bangladesh. Faecal samples had been collected at enrollment, on a routine monthly basis, and repeatedly during episodes of diarrhoea and infection with Giardia, and a portion of all samples was frozen in saline. A direct smear of all had been examined by microscopy and again after concentrating cysts by ether sedimentation. A total of 2121 of the 4936 samples stored during the 22 months study were tested by the ELISA. After excluding non-specific binding, the sensitivity of the assay was 94.2% and the specificity was 98%. The presence of other parasites, including flagellated protozoa, was not linked to false positive ELISA results. There was a correlation between the number of Giardia cysts present and the ELISA optical density. Assuming that the ELISA is 100% sensitive, microscopy detected 92.4% of the infections detected by the ELISA.


Subject(s)
Antigens, Protozoan/analysis , Feces/parasitology , Giardia/immunology , Giardiasis/diagnosis , Animals , Diarrhea/parasitology , Enzyme-Linked Immunosorbent Assay/methods , False Negative Reactions , False Positive Reactions , Giardia/isolation & purification , Humans , Infant , Prospective Studies
16.
Proc Natl Acad Sci U S A ; 85(12): 4340-4, 1988 Jun.
Article in English | MEDLINE | ID: mdl-16593944

ABSTRACT

Pollen hydration and self-incompatibility (SI) in Brassica have been studied by using a combination of in vivo video-microscopy and experiments with metabolic inhibitors. Experiments with cycloheximide confirm earlier observations that pollen hydration is regulated through protein synthesis. No protein or glycoprotein has positively been identified with this event; however, it is unlikely that the total pool of any particular glycoprotein is involved, but rather a newly synthesized or otherwise activated fraction. Micromanipulation of pollen on the stigmatic papillae suggests that access to this hydration regulation system is limited to members of the Brassicaceae: pollen grains of other species-even those possessing dry stigmas-fail to hydrate. It is proposed that an interaction between enzymes of the stigma surface and the superficial layer of the pollen grain coating creates continuity between the content of the papillar wall and the grain protoplast. Inhibition of protein synthesis also overcomes SI, and since the advent of regulated hydration and synthesis of the so-called S-gene glycoproteins coincide with the acquisition of the SI system, there is strong circumstantial evidence that the same molecular species is involved in both processes. Experiments with tunicamycin, which prevents glycosylation of glycoproteins, indicate that the glycosyl groups of the S-gene glycoprotein are required for the operation of the SI system but not for the regulation of hydration. Further experiments suggest that pollen is positively inhibited on incompatible papillae but that this inhibition is biostatic. Recovery from the effects of the SI system appears to involve the metabolism of an inhibitor by the pollen. SI in Brassica thus emerges as a sophisticated process under dynamic control in both the female and male partners. The evolutionary advantages of such a system are discussed.

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