Enhancement by microencapsulation of rotavirus-specific intestinal immune responses in mice assessed by enzyme-linked immunospot assay and intestinal fragment culture

The capacity of microencapsulation to enhance the humoral immune response to rotavirus in the gut-associated lymphoid tissue (GALT) of mice was determined by using a system of microencapsulation based on the ionic linkage of aqueous anionic polymers and an aqueous amine. Inoculation of mice with microencapsulated rotavirus enhanced the frequencies of virus-specific IgA-secreting cells in the lamina propria as well as the quantities of virus-specific IgA produced in GALT. In addition, an enhanced virus-specific immune response was associated with enhanced production of presumably polyclonal, non-rotavirus-specific antibodies in GALT. The mechanism by which microencapsulation enhances the humoral immune response remains to be determined.

Retained lens fragments after phacoemulsification

PURPOSE

The authors present the clinical features of patients with retained lens fragments after phacoemulsification and their outcome after pars plana vitrectomy.

METHODS

The authors performed a retrospective chart review of 62 patients who had surgical management of posteriorly dislocated lens fragments after phacoemulsification during the 3-year period from January 1990 to December 1992.

RESULTS

Eight of the 62 patients underwent vitrectomy on the same day as the cataract surgery. Of the remaining 54 patients examined in the outpatient clinic, initial clinical features included marked intraocular inflammation (87%), elevated intraocular pressure of 30 mmHg or higher (46%), and corneal edema (46%). Retinal detachment was present before vitrectomy in one patient and occurred after vitrectomy in two others. Initial visual acuity was 20/200 or worse in 68% of patients. After vitrectomy, final visual acuity was 20/40 or better in 68% of patients. Using the percentage of patients with 20/40 or better final visual acuity, there was no statistically significant difference in surgery performed within 7 days (70%), between 1 and 4 weeks (60%), and after 4 weeks (70%). Twenty (80%) of 25 patients with initial posterior chamber intraocular lenses (PC IOLs) and 16 (62%) of 26 patients with initial anterior chamber IOLs (AC IOLs) achieved 20/40 or better visual acuity. A visual acuity outcome of 20/200 or worse occurred in all three patients with retinal detachment. Six of the eight patients who underwent vitrectomy on the same day as the cataract surgery achieved 20/30 or better visual acuity.

CONCLUSIONS

The timing of vitrectomy did not influence visual acuity outcomes. Intraocular lenses inserted at the primary operation did not adversely affect the visual outcome. However, vitrectomy on the same day as cataract surgery generally yielded favorable visual acuity outcomes and eliminated the need for a second operation at a later date. In most patients with retained lens fragments, management with vitrectomy allowed good visual acuity outcomes.

Rotavirus-specific intestinal immune response in mice assessed by enzyme-linked immunospot assay and intestinal fragment culture

Primate rotavirus strain RRV and bovine strain WC3 or reassortants made between these animal viruses and human rotaviruses have been administered to infants as candidate vaccines. We compared RRV and WC3 in a murine model of oral infection. We determined the relative capacities of these viruses to induce a virus-specific humoral immune response by intestinal lymphocytes as tested by enzyme-linked immunospot assay, intestinal fragment culture, and enzyme-linked immunosorbent assay of intestinal contents. We found that inoculation of mice with RRV induced higher frequencies of virus-specific immunoglobulin A (IgA)-secreting cells in the lamina propria, greater quantities of virus-specific IgA in intestinal fragment cultures, and greater quantities of virus-specific IgA in intestinal secretions than did inoculation with WC3 or inactivated RRV (iRRV). The induction of an IgA response in serum was predictive of an IgA response among intestinal lymphocytes after inoculation with RRV but not WC3. In addition, large quantities of IgG, IgA, and IgM not specific for rotavirus were produced in fragment cultures from mice inoculated with RRV but not in cultures from mice inoculated with WC3 or iRRV. Possible mechanisms of RRV-induced polyclonal stimulation of intestinal B cells are discussed.

Enhancement of rotavirus immunogenicity by microencapsulation

It was determined whether microencapsulation of rotavirus enhanced virus-specific immunity in mice. Combinations of several water-soluble anionic polymers and amines were tested for their capacity to form microcapsules which were stable in the presence of simulated gastric acid. Using the combinations of sodium alginate and spermine hydrochloride or sodium chondroitin sulfate and spermine hydrochloride we found that microcapsules (1) captured infectious rotavirus, (2) penetrated into the persisted in gut-associated lymphoid tissue (GALT) after oral inoculation, (3) delivered rotavirus antigen to GALT at levels greater than those detected after oral inoculation with free virus, and (4) enhanced the virus-specific humoral immune response after oral or parenteral immunization.

MRI of total anomalous pulmonary venous connections

OBJECTIVE

A prospective MR study was undertaken in 13 patients with total anomalous pulmonary venous connection (TAPVC) to determine the value of MR in its detection.

MATERIALS AND METHODS

Echocardiography was performed in all cases and cardiac angiography was performed in eight patients before MRI.

RESULTS

Magnetic resonance detected TAPVC in four cases without prior echocardiographic and angiographic diagnosis. In seven surgically proven cases, the diagnostic accuracy of preoperative MR, echocardiography, and cardiac angiography was 100 (7 of 7), 57 (4 of 7), and 25% (1 of 4), respectively. In the remaining cases including three cases for postoperative evaluation, MR findings correlated well with those of echocardiography or angiography. The combination of axial and coronal MRI visualized 96% of the individual anomalous pulmonary veins and 100% of the common pulmonary veins. Stenosis of a common pulmonary vein (three cases) or the superior vena cava (one case) was identified on MR in all cases.

CONCLUSION

Magnetic resonance is an effective modality in depicting TAPVCs.

Physical Chemistry of the H2SO4/HNO3/H2O System: Implications for Polar Stratospheric Clouds

Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO(3) hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H(2)SO(4)/H(2)O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO(3) vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO(3) and H(2)O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H(2)SO(4) solutions and on solid H(2)SO(4) hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles.

An investigation of the rheological properties of 10 vinyl-polysiloxane impression materials

PURPOSE

The time required for 10 vinyl-polysiloxane impression materials to reach a viscosity of 5000 poise (Tcv) was estimated. This viscosity was selected based on previous work that suggested that an impression material might not be workable if its viscosity exceeded this limit. The effect of variations in the time of placement of the impression materials into a simulated oral-temperature environment was also studied.

MATERIALS AND METHODS

The change in the viscosity of the impression materials was recorded with a viscometer at oral temperature. Impression materials were placed at either 20 seconds, 30 seconds, or 40 seconds from the start of mixing.

RESULTS

There were statistically significant differences in Tcv among various impression materials. Variations in placement time significantly affected the Tcv of six impression materials.

CONCLUSIONS

Knowledge of the viscosity change of an impression material is beneficial in the clinical selection of an impression material.

Characterization of a helper T cell epitope recognized by mice of a low responder major histocompatibility type

Most known helper T cell (Th) epitopes studied have naturally been immunodominant epitopes recognized by T cells from animals of high responder major histocompatibility complex (MHC) haplotype. We have previously found that most such immunodominant Th epitopes tend to be amphipathic alpha helices, that is, helices with hydrophobic residues on one side and hydrophilic residues on the other, and the corresponding peptide can usually elicit a response to the native protein. However, very few epitopes seen by MHC low responder T cells have been identified. Within the CNBr fragment of residues 1-55 of sperm whale myoglobin (SwMb), a Th epitope is known to exist that stimulates T cells from low responder H-2k mice, but it has not yet been localized to a length of 8-12 residues, the usual length of a Th epitope. To determine whether this low responder epitope would have similar properties, we located it using 10 evenly overlapping 15-residue peptides that span the region. Analysis of this region by the computer program predicted the site covered by two peptides (residues 26-40 and 31-45 which overlap by 10 residues) to be the most likely site for a Th epitope. Of the 10 peptides tested experimentally, only one peptide (residues 26-40) was able to stimulate two low responder Th clones that are specific for the 1-55 region. The peptide was able to prime T cells of low responder B10.BR mice in vivo for in vitro response to the native SwMb as well as to the peptide fragment of residues 1-55. Immunization of low responder mice with SwMb showed that, of the 10 overlapping peptides, the major site of response within the 1-55 region is to the identified peptide. Finally, an extended peptide of residues 24-42 was made to increase the amphipathic score. This extended peptide induced greater proliferation of the clones. Thus, this low responder epitope has properties similar to those of immunodominant epitopes recognized by high responders.

Actinobacillus pleuropneumoniae hlyX gene homology with the fnr gene of Escherichia coli

The hlyX gene from Actinobacillus pleuropneumoniae, which confers a hemolytic phenotype on Escherichia coli, was sequenced, and its role in regulation of gene expression was investigated. No similarity was found between the hlyX sequence and sequences of known hemolysin or cytotoxin genes. However, the hlyX sequence was very similar to that of the fnr gene of Escherichia coli which encodes the global regulatory protein, FNR. Comparison of the deduced amino acid sequence of the hlyX gene product (HlyX) with that of FNR revealed a high degree of well-aligned sequence correlation throughout the polypeptide chain. For example, 23 of 24 amino acids in the DNA-binding region of FNR are identical in the corresponding region of HlyX. Four cysteine residues in the amino-terminal region are also conserved. The promoter region of hlyX is very similar to that of fnr. It has a putative -10 sequence which closely resembles the E. coli -10 consensus sequence. This sequence is overlapped by a potential operator which is very similar to the FNR-binding-site consensus sequence. Functional homology between HlyX and FNR was also demonstrated. Plasmids carrying hlyX complemented the nutritional lesion of an fnr deletion strain of E. coli. These data suggest that HlyX may regulate, rather than mediate, hemolytic activity in E. coli, but the possibility that HlyX is both a regulator of gene expression and a hemolysin cannot be excluded.

Polyvalent human immunodeficiency virus synthetic immunogen comprised of envelope gp120 T helper cell sites and B cell neutralization epitopes

In previous studies, we have used antisera raised to envelope (env)-gene-encoded synthetic peptides to identify a region of (HIV) glycoprotein (gp) 120 env protein designated SP10 that contains a type-specific neutralizing determinant. To develop a polyvalent, synthetic peptide inoculum that can evoke both neutralizing antibodies and T cell proliferative responses to more than one HIV isolate, synthetic peptides containing type-specific neutralizing determinants of gp120 from HIV isolates HTLV-IIIB (IIIB), HTLV-IIIMN (MN) and HTLV-IIIRF (RF) were coupled to a 16 amino acid T cell epitope (T1) of HIV-IIIB gp120 and used to immunize goats. Goat antisera to each T1-SP10 peptide derived from the SP10 region of gp120 of IIIB, MN, and RF neutralized HIV isolates IIIB, MN and RF in a type-specific manner. Moreover, peripheral blood T cells from immunized goats also proliferated in a type-specific manner to peptides derived from gp120 of IIIB, MN, and RF. When combined in a trivalent inoculum, T1-SP10 peptides from HIV-1 isolates IIIB, MN, and RF evoked a high titered neutralizing antibody response to isolates IIIB, MN, and RF in goats and as well induced immune T cells to undergo blast transformation in the presence of peptides derived from gp120 of all three HIV isolates. The T1 portion of the T1-SP10 construct was shown to induce a B cell antibody response against determinants within the T1 peptide in addition to inducing T cell proliferative responses in immune goat T cells. Moreover, the SP10 portion of the T1-SP10 constructs not only induced B cell antibody production but also induced type-specific T cell proliferative responses localized to the C-terminal variable sequences of the SP10 peptides. Finally, the T1-SP10 peptide construct induced memory T cell proliferative responses to native gp120 env protein. Thus, combinations of homologous SP10 region synthetic peptides containing type-specific neutralizing determinants and T cell epitopes of HIV gp120 may be useful in man to elicit high titered neutralizing B cell responses and, as well, T cell responses to more than one HIV isolate.

Polyvalent human immunodeficiency virus synthetic immunogen comprised of envelope gp120 T helper cell sites and B cell neutralization epitopes

In previous studies, we have used antisera raised to envelope (env)-gene-encoded synthetic peptides to identify a region of (HIV) glycoprotein (gp) 120 env protein designated SP10 that contains a type-specific neutralizing determinant. To develop a polyvalent, synthetic peptide inoculum that can evoke both neutralizing antibodies and T cell proliferative responses to more than one HIV isolate, synthetic peptides containing type-specific neutralizing determinants of gp120 from HIV isolates HTLV-IIIB (IIIB), HTLV-IIIMN (MN) and HTLV-IIIRF (RF) were coupled to a 16 amino acid T cell epitope (T1) of HIV-IIIB gp120 and used to immunize goats. Goat antisera to each T1-SP10 peptide derived from the SP10 region of gp120 of IIIB, MN, and RF neutralized HIV isolates IIIB, MN and RF in a type-specific manner. Moreover, peripheral blood T cells from immunized goats also proliferated in a type-specific manner to peptides derived from gp120 of IIIB, MN, and RF. When combined in a trivalent inoculum, T1-SP10 peptides from HIV-1 isolates IIIB, MN, and RF evoked a high titered neutralizing antibody response to isolates IIIB, MN, and RF in goats and as well induced immune T cells to undergo blast transformation in the presence of peptides derived from gp120 of all three HIV isolates. The T1 portion of the T1-SP10 construct was shown to induce a B cell antibody response against determinants within the T1 peptide in addition to inducing T cell proliferative responses in immune goat T cells. Moreover, the SP10 portion of the T1-SP10 constructs not only induced B cell antibody production but also induced type-specific T cell proliferative responses localized to the C-terminal variable sequences of the SP10 peptides. Finally, the T1-SP10 peptide construct induced memory T cell proliferative responses to native gp120 env protein. Thus, combinations of homologous SP10 region synthetic peptides containing type-specific neutralizing determinants and T cell epitopes of HIV gp120 may be useful in man to elicit high titered neutralizing B cell responses and, as well, T cell responses to more than one HIV isolate.