Biomedical subjects

B Ye

Publications and source records attributed to B Ye.

At least 37 records · Page 2Linked to original sources

PubMed1998

unc-3, a gene required for axonal guidance in Caenorhabditis elegans, encodes a member of the O/E family of transcription factors.

The expression of specialized signal transduction components in mammalian olfactory neurons is thought to be regulated by the O/E (Olf-1/EBF) family of transcription factors. The O/E proteins are expressed in cells of the olfactory neuronal lineage throughout development and are also expressed transiently in neurons in the developing nervous system during embryogenesis. We have identified a C. elegans homologue of the mammalian O/E proteins, which displays greater than 80% similarity over 350 amino acids. Like its mammalian homologues, CeO/E is expressed in certain chemosensory neurons (ASI amphid neurons) throughout development and is also expressed transiently in developing motor neurons when these cells undergo axonal outgrowth. We demonstrate that CeO/E is the product of the unc-3 gene, mutations in which cause defects in the axonal outgrowth of motor neurons, as well as defects in dauer formation, a process requiring chemosensory inputs. These observations suggest that the O/E family of transcription factors play a central and evolutionarily conserved role in the expression of proteins essential for axonal pathfinding and/or neuronal differentiation in both sensory and motor neurons.

Aging↗

PubMed1998

[A comparative study on transabdominal versus retroperitoneal approach for abdominal aortic surgery].

OBJECTIVE: To retrospectively compare transabdominal with retroperitoneal approach to the aorta for infrarenal aortic reconstruction. METHODS: From January 1988 to December 1996, Patients undergoing surgery for abdominal aortic aneurysm (AAA) or aortoiliac occlusive disease (AIOD) were included in the retrospective comparison of transabdominal approach (TAA) with retroperitoneal approach (RPA) for aortic surgery. Forty-four patients were analyzed, with 26 (23 with AAA and 3 with AIOD) in TAA group and 18 (16 with AAA and 2 with AIOD) in RPA group. There were no significant differences between the groups in terms of age, sex, comorbid conditions, and vascular graft anastomoses. RESULTS: The incidence of intraoperative complications was similar for both groups. Postoperatively, RPA group had significantly fewer overall complications than TAA group (P < 0.01). The incidence of prolonged ileus (6 cases in TAA group, none in RPA group) and small bowel obstruction (2 cases in TAA group, none in RPA group) was higher in the TAA group (P < 0.01). Postoperatively four deaths occurred with two in each group. There was no difference in pulmonary complications (P = 0.70). In long-term follow-up (mean 32 months), no significant difference was found in incisional hernias in the two groups. CONCLUSIONS: RPA approach, with fewer postoperative complications, short stay in the hospital and intensive care unit, is a safer and simpler approach for abdominal aortic surgery.

Aged↗

PubMed1998

[Genetic analysis of deltamethrin resistance in Culex pipiens pallens].

AIM: To analyse the genetic character of deltamethrin resistant laboratory strain (resistant factor being 518) of Cx. pipiens pallens. METHODS: Genetic studies were made of deltamethrin-susceptible and-resistant strains of Cx. pipiens pallens with LC-P curve constructed from the response of fourth instar larvae to deltamethrin treatment, and the resistance mechanisms were analysed with synergetic tests in PB, DEF and TPP. RESULTS: The resistant factors of F1 generation from cross and reciprocal cross are respectively 154.8 and 159.2; the LC-P curve of F1 generation gets near to that of resistant parents, D = 0.625; there exist no obvious platform in 50% mortality of BC generation and 25% and 75% mortality of F2 generation, and there are larger differences between the determining curve and theoretical curve in both BC and F2 generations, P < 0.01; the synergetic ratios of PB, DEF and TPP are 27.13, 1.22 and 1.05. CONCLUSION: Deltamethrin resistance of Cx. pipiens pallens is controlled by two or more autosomal genes, and the main gene involved is incompletely dominant; multi-functional oxidase is mainly responsible for the resistance.

Animals↗

PubMed1998

[Sensitivity and specificity of nested polymerase chain reaction in detecting Plasmodium vivax in infected mosquitoes].

AIM: To study the sensitivity and specificity of nested polymerase chain reaction for detection of Plasmodium vivax in infected mosquitoes. METHODS: Two pairs of primers specific to small subunit ribosomal DNA of P. vivax were used to amplify the specific SSUrDNA 121 bp fragment of P. vivax for detecting P. vivax-infected mosquitoes with nested PCR. RESULTS: Nested PCR could detect as few as 3 sporozoites in one mosquito or 1 infected mosquito mixed with a group of 99 normal ones. In contrast, no such specific 121 bp DNA band was detected in P. falciparum, P. cynomolgi, P. yoelii yoelii infected samples, nor in normal mosquito. CONCLUSION: The nested PCR technique we established showed high sensitivity and specificity.

Animals↗

PubMed1997

A high-sensitivity, single-gel, polyacrylamide gel electrophoresis method for the quantitative determination of glutathione reductases.

A new method is described that allows the selective staining and quantification of gluthathione reductases (EC 1.6.4.2) in cell extracts following acrylamide gel electrophoresis. The method is based on modifications of two previous procedures; it uses DTNB [5,5'-dithiobis(2-nitrobenzoic acid)] to develop a yellow color on reaction with GSH formed from the NADPH-dependent reduction of oxidized glutathione. This is followed by specific counterstaining of glutathione reductase with dichlorophenolindophenol/nitroblue tetrazolium. The use of DTNB in the initial staining step inhibits enzymes other than glutathione reductase that could be stained with the dichlorophenolindophenol/nitroblue tetrazolium counterstain. Enzymes such as thioredoxin reductase, which can directly reduce DTNB with NADPH, may be nonselectively stained by this new procedure. Plant ferredoxin-thioredoxin reductase is not reduced by NADPH and therefore does not appear. Glutathione reductase stains much quicker with DTNB in the presence of GSSG than with thioredoxin reductase, allowing them to be distinguished, if parallel gels are run without GSSG, where the two enzymes react at the same rate. The sequential use of two staining procedures results in distinct, sharp permanent bands that can be used to quantify the activity of glutathione reductase while precluding artifacts generated by the previous methods.

2,6-Dichloroindophenol↗

PubMed1997

Potent inhibition of protein-tyrosine phosphatase by phosphotyrosine-mimic containing cyclic peptides.

In an effort to derive potent and bioavailable protein-tyrosine phosphatase inhibitors, we have previously reported hexameric peptides based on the epidermal growth factor receptor sequence EGFR988-993 (Asp-Ala-Asp-Glu-Xxx-Leu, where Xxx = Tyr), in which the tyrosyl residue has been replaced by the non-hydrolyzable phosphotyrosyl mimics phosphonomethylphenylalanine (Pmp), difluorophosphonomethylphenylalanine (F2Pmp) and O-malonyltyrosine (OMT). Inhibitory potencies (IC50 values) of these peptides against the tyrosine phosphatase PTP IB were 200, 0.2 and 10 microM, respectively. Since cellular penetration of peptides containing highly charged phosphonate residues is compromised, and good bioreversible protection strategies for the F2Pmp residue have not yet been reported, the OMT residue is of particular interest in that it affords potential new prodrug approaches. In the current study we have prepared cyclized versions of the OMT-containing EGFR988-993 peptide in order to increase its proteolytic stability and restrain conformational flexibility. Three different cyclic analogues were synthesized. Two of these were cyclized through the peptide backbone ('head to tail') using in one case a single glycine spacer (heptamer peptide) and in the second instance, two glycines (octamer peptide). In a PTPI-based assay the cyclic heptamer experienced a two-fold loss of potency (Ki = 25.2 +/- 3.9 microM) relative to the linear hexamer parent (Ki = 13 +/- 0.9 microM), while the cyclic octamer demonstrated a live-fold increase in potency (Ki = 2.60 +/- 0.11 microM). The third peptide was cyclized by means of a sulfide bridge between the side chain of a C-terminally added cysteine residue and the beta-carbon of a N-terminal acetyl residue. Although the overall size of this ring was identical to that exhibited by the preceding backbone-cyclized octamer, it displayed a three-fold enhancement in potency (Ki = 0.73 +/- 0.03 microM). The structural basis for the observed results are discussed. Conformation restrictions induced by cyclization could aid in defining geometries for peptidomimetic design. Finally, it can be speculated that cyclization of other liner PTP-inhibitory peptides, such as the F2Pmp-containing hexamer, may also increase their potency.

Biological Availability↗

PubMed1997

Protein kinase C activity and light sensitivity of single amphibian rods.

Biochemical experiments by others have indicated that protein kinase C activity is present in the rod outer segment, with potential or demonstrated targets including rhodopsin, transducin, cGMP-phosphodiesterase (PDE), guanylate cyclase, and arrestin, all of which are components of the phototransduction cascade. In particular, PKC phosphorylations of rhodopsin and the inhibitory subunit of PDE (PDE ) have been studied in some detail, and suggested to have roles in downregulating the sensitivity of rod photoreceptors to light during illumination. We have examined this question under physiological conditions by recording from a single, dissociated salamander rod with a suction pipette while exposing its outer segment to the PKC activators phorbol-12-myristate,13-acetate (PMA) or phorbol-12,13-dibutyrate (PDBu), or to the PKC-inhibitor GF109203X. No significant effect of any of these agents on rod sensitivity was detected, whether in the absence or presence of a background light, or after a low bleach. These results suggest that PKC probably does not produce any acute downregulation of rod sensitivity as a mechanism of light adaptation, at least for isolated amphibian rods.

Ambystoma↗

PubMed1997

Cellular effects of phosphotyrosine-binding domain inhibitors on insulin receptor signaling and trafficking.

Shc and insulin receptor substrate 1 (IRS-1) are cytoplasmic substrates of tyrosine kinase receptors that engage, localize, and activate downstream SH2 enzymes. Each contains a phosphotyrosine-binding (PTB) domain that is structurally unrelated to SH2 domains. We have designed high-affinity, cellular inhibitors of the Shc PTB domain by incorporating nonnatural, phosphatase-resistant amino acids into short peptides. None of the inhibitors bind the IRS-1 PTB domain, consistent with distinct specificities for domains. The best inhibitor of the Shc domain was introduced by electroporation into Rat1 fibroblasts that express human insulin receptors. Insulin-stimulated phosphorylation of Shc was inhibited, with no effect on IRS-1, and downstream effects on mitogen-activated protein kinase and DNA synthesis were both inhibited. The PTB domain inhibitor had less influence on epidermal growth factor-induced effects and essentially no impact on serum- or phorbol ester-induced effects. The inhibitor did not affect insulin internalization and its degradation. We conclude that the PTB domain of Shc is critical for its phosphorylation by the insulin receptor, that Shc is an important mediator of insulin's mitogenic effects, and that Shc is not central to insulin receptor cycling in these cells. PTB domains can be inhibited selectively in cells and represent potential targets for drug discovery.

Adaptor Proteins, Signal Transducing↗

PubMed1997

[Effects of different components of serum from radiation, burn and combined radiation-burn injury on L-type calcium channel of cultured myocardial cells].

The effects of different components of serum from radiation, burn and combined radiation-burn injury on the activity of L-type calcium channel in cultured myocardial cells were investigated in this study. The results revealed that the serum from different injury groups could all activate the L-type calcium channel of cultured myocardial cells. These changes altered the calcium level in cells, which might be an important cause of dysfunction in cardiovascular system. Among the components of postinjury serum, the effect of high molecular components (> 8-10 kD) was not significant, whereas low molecule (< 8-10kD) and lipid components were the major effective components. The low molecule of postinjury serum affected not only on the opening activity of L-type channel, but also on the state of molecular movement in the membrane. The effect of serum lipids from injury groups could be depressed by SOD, which suggests that there may be free radical reactions during the serum lipids effect on calcium channel. The effects of serum and its components from combined radiation-burn group were the most intensive, and those from radiation injury were the weakest. The nature of the toxic material in serum remains to be further investigated.

Animals↗

PubMed1996

Small molecule interactions with protein-tyrosine phosphatase PTP1B and their use in inhibitor design.

We have previously shown that a small peptide bearing the hydrolytically stable phosphotyrosyl (pTyr) mimetic, (difluorophosphonomethyl) phenylalanine (F2Pmp), is an extremely potent inhibitor of PTP1B, with an IC50 value of 100 nM [Burke, T. R., Kole, H. K., & Roller, P. P. (1994) Biochem. Biophys. Res. Commun. 204, 129-134]. We further demonstrated that removal of the peptide portion and incorporation of the difluorophosphonomethyl moiety onto a naphthalene ring system, but not a phenyl ring system, resulted in good inhibitory potency [Kole, H. K., Smyth, M. S., Russ, P. L., & Burke, T. R., Jr. (1995) Biochem, J. 311, 1025-1031]. In order to understand the structural basis for this inhibition, and to aid in the design of further analogs, we solved the X-ray structure of [1, 1-difluoro-1-(2-naphthalenyl)-methyl]phosphonic acid (6) complexed within the catalytic site of PTP1B, solved to 2.3 A resolution. In addition to showing the manner in which the phosphonate group is held within the catalytic site, the X-ray structure also revealed extensive hydrophobic interactions with the naphthalene ring system, beyond that possible with an analog bearing a single phenyl ring. It is further evident that, of the two fluorine atoms, the pro-R alpha-fluorine interacts with the enzyme to a significantly greater degree than the pro-S alpha-fluorine, forming a hydrogen bond to Phe 182. On the basis of a computer-assisted molecular modeling analysis, it was determined that addition of a hydroxyl to the naphthyl 4-position, giving [1, 1-difluoro-1-[2-(4-hydroxynaphthalenyl)] methyl]phosphonic acid (8), could potentially replace a water molecule situated in the PTP1B-6 complex, thereby allowing new hydrogen-bonding interactions with Lys 120 and Tyr 46. Compound 8 was therefore prepared and found to exhibit a doubling of affinity (Ki = 94 microM) relative to parent unsubstituted 6 (Ki = 179 microM), supporting, in principle, the development of high-affinity ligands based on molecular modeling analysis of the enzyme-bound parent.

Binding Sites↗

PubMed1996

Cell protein cross-linking by erbstatin and related compounds.

The protein-tyrosine kinase inhibitor and stable erbstatin analogue methyl 2,5-dihydroxycinnamate (4) cross-links cell proteins by a non-physiological chemical mechanism (Stanwell et al., Cancer Res 55: 4950-4956, 1995). To determine the structural requirements for this effect, erbstatin (1) and fifteen related compounds, including caffeic acid phenylethyl ester (9) were synthesized and examined for their ability to induce cross-linking of cellular protein at concentrations ranging from low micromolar up to 1000 microM. Tests were conducted in NIH3T3 fibroblasts as well as mouse keratinocytes. Potent cross-linking of cellular protein was observed for a number of analogues, including erbstatin, at concentrations as low as 10-50 microM. The inactivity of methoxy and fluoro as compared with their corresponding dihydroxylated counterparts indicated that free aromatic hydroxyls were essential for cross-linking. Additionally, compounds containing phenyl rings with 1,4-dihydroxy substituents were more potent than those having 1,2-dihydroxylated patterns. As with the prototype compound 4, cross-linking was induced at both 37 degrees and 4 degrees, suggesting a chemical rather than physiological mechanism. Consistent with the data, a mechanism of action is proposed which involves initial oxidation to reactive quinone intermediates that subsequently cross-link protein nucleophiles via multiple 1,4-Michael-type additions. Similar alkylation of protein by protein-tyrosine kinase inhibitors, such as herbimycin A, has been invoked. While the latter benzoquinoid ansamycin antibiotics contain performed quinone moieties, results of the present study suggest that other hydroxylated kinase inhibitors can potentially participate in similar phenomena. A large number of potential therapeutics, including HIV integrase inhibitors, possess polyhydroxylated nuclei. The non-specific nature of the protein cross-linking reaction demonstrated for these erbstatin analogues, and the fact that cross-linking can occur at micromolar concentrations, may limit the therapeutic usefulness of such compounds to specific applications.

Animals↗

PubMed1996

4'-O-[2-(2-fluoromalonyl)]-L-tyrosine: a phosphotyrosyl mimic for the preparation of signal transduction inhibitory peptides.

Development of phosphotyrosyl (pTyr) mimetics which are stable to protein-tyrosine phosphatases (PTPs), yet can retain biological potency when incorporated into peptides, is an active area of drug development. Since a majority of pTyr mimetics derive their "phosphofunctionality" from phosphorus-containing moieties, such as phosphonates, evolution of new inhibitors and modes of prodrug derivatization have been restricted to chemistries appropriate for phosphorus-containing moieties. A new, nonphosphorus-containing pTyr mimetic has recently been reported, L-O-(2-malonyl)tyrosine (OMT,5), which can be incorporated into peptides that exhibit good PTP and Src homology 2 (SH2) domain inhibitory potency. For phosphonate-based pTyr mimetics such as phosphonomethyl phenylalanine (Pmp,2) introduction of fluorines alpha to the phosphorus has provided higher affinity pTyr mimetics. This strategy has now been applied to OMT, and herein is reported 4'-O-[2-(2-fluoromalonyl)]-L-tyrosine (FOMT,6) a new fluorine-containing nonphosphorus pTyr mimetic. Incorporation of FOMT into appropriate peptides results in good inhibition of both PTP and SH2 domains. In an assay measuring the inhibition of PTP 1B-mediated dephosphorylation of phosphorylated insulin receptor, the peptide Ac-D-A-D-E-X-L-amide exhibited a 10-fold enhancement in inhibitory potency for X = FOMT (19) (IC(50) = 10 microM) relative to the unfluorinated peptide, X = OMT (18) (IC(50) = 10 microM. Molecular modeling indicated that this increased affinity may be attributable to new hydrogen-bonding interactions between the fluorine and the enzyme catalytic site, and not due to lowering of pKa values. In a competition binding assay using the p85 PI 3-kinase C-terminal SH2 domain GST fusion construct, the inhibitory peptide, Ac-D-X-V-P-M-L-amide, showed no enhancement of inhibitory potency for X = FOMT (22) (IC(50) = 18 microM) relative to the unfluorinated peptide, X = OMT (21) (IC(50) = 14 microM). The use of FOMT would therefore appear to have particular potential for the development of PTP inhibitors.

Amino Acid Sequence↗

PubMed1996

Comparison of dark- and light-adapted carp retinas with NADPH diaphorase staining.

The carp retina was examined by NADPH diaphorase histochemistry to determine if the staining pattern of retinal cells was changed depending on the adaptation state of the retina. When dark-adapted for 5 h, ellipsoids of inner segments of both rods and cones and some horizontal cells were heavily stained. Staining was also found in subpopulations of amacrine cells and ganglion cells. In addition, Müller cells were strongly positive for NADPH diaphorase. When light-adapted for 5 h, ellipsoids of photoreceptors and ganglion cells were less intensely stained, whereas Müller cells and horizontal cells became negative for NADPH diaphorase. Furthermore, rod ON-center bipolar cells were clearly stained. The difference of staining of amacrine cells between dark- and light-adapted retinas was not significant. The differences in diaphorase-staining pattern between dark- and light-adapted retinas suggest that Müller cells, some horizontal cells and rod ON-center bipolar cells contain inducible nitric oxide synthase, whose induction depends on the adaptation state.

Adaptation, Ocular↗

PubMed1995

L-O-(2-malonyl)tyrosine: a new phosphotyrosyl mimetic for the preparation of Src homology 2 domain inhibitory peptides.

Inhibition of Src homology 2 (SH2) domain-binding interactions affords one potential means of modulating protein-tyrosine kinase-dependent signaling. Small phosphotyrosyl (pTyr)-containing peptides are able to bind to SH2 domains and compete with larger pTyr peptides or native pTyr-containing protein ligands. Such pTyr-containing peptides are limited in their utility as SH2 domain inhibitors in vivo due to their hydrolytic lability to protein-tyrosine phosphatases (PTPs) and the poor cellular penetration of the ionized phosphate moiety. An important aspect of SH2 domain inhibitor design is the creation of pTyr mimetics which are stable to PTPs and have reasonable bioavailability. To date, most PTP-resistant pTyr mimetics which bind to SH2 domains are phosphonates such as (phosphonomethyl)phenylalanine (Pmp, 2), [(monofluorophosphono)methyl]phenylalanine (FPmp, 3) or [(difluorophosphono)methyl]-phenylalanine (F2Pmp, 4). Herein we report the incorporation of a new non-phosphorus-containing pTyr mimetic, L-O-(2-malonyl)tyrosine (L-OMT, 5), into SH2 domain inhibitory peptides using the protected analogue L-N alpha-Fmoc-O'-(O",O"-di-tert-butyl-2-malonyl)tyrosine (6) and solid-phase peptide synthesis techniques. Five OMT-containing peptides were prepared against the following SH2 domains: the PI-3 kinase C-terminal p85 SH2 domain (Ac-D-(L-OMT)-V-P-M-L-amide, 10, IC50 = 14.2 microM), the Src SH2 domain (Ac-Q-(L-OMT)-E-E-I-P-amide, 11, IC50 = 25 microM, and Ac-Q-(L-OMT)-(L-OMT)-E-I-P-amide, 14, IC50 = 23 microM), the Grb2 SH2 domain (Ac-N-(L-OMT)-V-N-I-E-amide, 12, IC50 = 120 microM), and the N-terminal SH-PTP2 SH2 domain (Ac-L-N-(L-OMT)-I-D-L-D-L-V-amide, 13, IC50 = 22.0 microM). These results show that peptides 10, 11, 13, and 14 have reasonable affinity for their respective SH2 domains, with the IC50 value for the SH-PTP2 SH2 domain-directed peptide 13 being equivalent to that previously observed for the corresponding F2Pmp-containing peptide. OMT may afford a new structural starting point for the development of novel and useful SH2 domain inhibitors.

Amino Acid Sequence↗

PubMed1995

Protein-tyrosine phosphatase inhibition by a peptide containing the phosphotyrosyl mimetic, L-O-malonyltyrosine.

Peptides containing phosphonate based non-hydrolyzable phosphotyrosyl (pTyr) mimetics previously have been shown to be competitive inhibitors of protein-tyrosine phosphatases (PTPs). These agents suffer from low cellular penetration which is partially attributable to ionization of the phosphonate group at physiological pH. We have developed the non-phosphorus containing pTyr mimetic, L-O-malonyltyrosine (L-OMT) and herein demonstrate using a PTP 1B enzyme assay that it is superior to phosphonomethyl phenylalanine (Pmp) as a pTyr mimetic when incorporated into the hexamer peptide Ac-D-A-D-E-X-L-amide (X = D,L-Pmp, IC50 = 200 microM; X = L-OMT, IC50 = 10 microM). Prodrug protection of L-OMT as its carboxylic acid diester could potentially increase cellular penetration, thereby making this a valuable reagent for cellular studies.

Amino Acid Sequence↗

PubMed1995

Selectivity control in micellar electrokinetic chromatography of small peptides using mixed fluorocarbon-hydrocarbon anionic surfactants.

Electrophoretic mobilities and capacity factors for a group of Trp-containing small peptides were determined by micellar electrokinetic chromatography (MEKC) using mixtures of a fluorocarbon anionic surfactant, lithium perfluorooctane sulfonate, and a hydrocarbon anionic surfactant, lithium dodecyl sulfate. Upon mixing these two surfactants, which have different microenvironments and interactive characteristics, greater control over migration of solutes is achieved. The changes in the composition of mixed micelles such as the mole fraction of the surfactants result in different solute-micelle binding as well as migration times of the micelles (tmc). Consequently, capacity factor, selectivity and elution window (tmc/t0) change with the composition of the mixed micellar system. Another characteristic of the mixtures of fluorocarbon-hydrocarbon surfactants is the possibility of forming two different types of micelles which offers an additional partitioning process for each solute in the MEKC system. Such a unique phenomenon offers a higher degree of selectivity control. This mixed MEKC system is quite effective for the separation of small peptides. It provides an alternative to the free-solution capillary zone electrophoresis system for the separation of charged solutes with nearly identical electrophoretic mobility.

Amino Acid Sequence↗

PubMed1995

Demonstration of in vitro cultured exoerythrocytic schizonts and hypnozoites of Plasmodium vivax (southern China isolate) by an immunoperoxidase antibody technique.

By indirect immunoperoxidase staining, different forms of exoerythrocytic (EE) stage of Plasmodium vivax (Southern China isolates) are revealed in d8 cultured material. The mature schizonts are elongated in shape measuring 42-48 microns in diameter, immature schizonts 14-28 microns and hypnozoites 4-7 microns. EE schizonts are stained dark-brown only after conjugated by monoclonal antibody (McAb) 4B2 specific against erythrocytic stages of P. vivax while hypnozoites are only stained after conjugated by McAb 2F2 against sporozoite. These results show that the antigenic components of these two forms of EE plasmodia are quite different. The ratio of EE schizont and hypnozoite found within hepatoma cells (HepG2-A16) is 1.5 to 1. Referred to the clinical manifestations of the isolate, among 5 volunteers not radically cured, two had long incubation period (283 d and 304 d, respectively) and three relapsed 235, 260 and 365 days after the primary attack. These data are unanimous with the comparatively large ratio of hypnozoites in the cultured material.

Animals↗

PubMed1995

[Effect of environmental temperature, cryopreservation and aging on Plasmodium vivax sporozoites developing into exoerythrocytic stages].

After Anopheles stephensi mosquitoes with salivary infection of Plasmodium vivax were put in environments with temperatures of 30 +/- 1 degrees C, 26 +/- 1 degrees C or 13 +/- 1 degrees C for 5 d, their glands were aseptically dissected and sporozoites were collected and inoculated into HepG2-A16 cell monolayers. Seven days post-inoculation the cultured materials were harvested and the exoerythrocytic schizonts and hypnozoites were observed under the microscope by using immunoperoxidase staining technique. The results showed that the sporozoite developing rate of 30 +/- 1 degrees C group and 13 +/- 1 degrees C group was significantly lower than that of 26 +/- 1 degrees C group (0.33%, 0.35% and 0.75% respectively). The proportion of hypnozoites in the total number of EE forms was the highest in the low temperature group (62.5%) compared with 26 +/- 1 degrees C and 30 +/- 1 degrees C group (40.1% and 42.7% respectively). Suggesting that the low environmental temperature first affected the viability of tachysporozoites or the phenotype of sporozoites and thus resulted in heightened hypnozoite rate. This is parallel to the epidemiological data that in the regions of high latitute vivax malaria with long incubation period was more frequently observed. When the sporozoites within the body of mosquito were cryopreserved at -70 degrees C or in liquid nitrogen for 24 h or 5 d respectively, the proportion of hypnozoite increased 87.4% and 82.4%, respectively. However, cryopreservation did not inactivate all of the tachysporozoites, indicating that the resistance to ultralow temperature in bradysporozoite was much greater than that in tachysporozoites. Aging of sporozoites decreased their developing rate and the exoerythrocytic (EE) schizonts were found to grow sluggishly and asynchronously, indicating that the size of EE schizont and the age of sporozoites are in negative correlation. Meantime, proportion of the hyponozoite decreased significantly.

Aging↗