Effect of particle lipid content on the structure of insect lipophorins

Four distinct subspecies of the major insect lipoprotein, lipophorin, that range in overall lipid content from 20 to 51% of the particle mass, were isolated from the hemolymph or oocytes of the tobacco hornworm, Manduca sexta. Examination of these subspecies by electron microscopy revealed distinctive morphologies. Adult high density lipophorin (HDLp-A) was found to be an approximately spherical particle with a diameter of 15 +/- 1 nm, while HDLp-Wanderer 1 (W1), was more rectangular in shape and had a distinct cleft extending into the particle at one end. In the case of HDLp-Wanderer 2 (W2) the cleft was deeper and wider than that in HDLp-W1. In egg very high density lipophorin (VHDLp-E) the cleft was increased in size to the extent that the particle had an overall crescent-like conformation. Circular dichroism spectroscopy of the three lipophorin subspecies that contain only apolipophorin I and II revealed that only minor differences in the global protein secondary structure occur as the particle lipid content is decreased. The VHDLp-E apolipoproteins are an exception in that, while having the same alpha-helix content as HDLp-W1 and HDLp-W2, they contain less beta-structure and correspondingly more random coil. Limited digestion of the apolipoprotein components of the lipophorin subspecies with trypsin revealed that as the lipid content of the particles decreases the susceptibility of the apolipoprotein to proteolytic degradation increases. Likewise, tryptophan fluorescence quenching experiments demonstrated that the relative exposure of lipophorin apolipoprotein tryptophan residues also increases as the particle lipid content decreases.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of ampicillin/sulbactam and amoxicillin/clavulanic acid for detection of borderline oxacillin-resistant Staphylococcus aureus

Borderline oxacillin-resistant Staphylococcus aureus (BORSA) may be misidentified as intrinsically methicillin-resistant Staphylococcus aureus (MRSA) in the clinical laboratory. Under disk diffusion testing conditions designed to maximize detection of MRSA (incubation at 32 degrees C, pre-induction with methicillin, or plating on 4% NaCl-supplemented agar), BORSA strains also tend to appear resistant to semisynthetic penicillins. Under these conditions, ampicillin/sulbactam appears to be more accurate than amoxicillin/clavulanic acid for differentiating BORSA from MRSA.

Modified hemoglobin solution as possible perfusate relevant to organ transplantation

A modified hemoglobin solution (<pyridoxylated hemoglobin>-<polyoxyethylene> conjugate solution, PHP solution) has very interesting characteristics such as oxygen-carrying property without corpuscular components. Experimental use of the PHP solution has shown promising possibilities as a perfusate relevant to organ transplantations. 1) Elongation of warm ischemic time in canine kidneys: Dogs survived even with the unilateral kidneys which had been exposed up to 4.5 hour warm ischemia and, thereafter, perfused with the PHP solution. 2) Elongation of perfusion preservation period of canine livers: Dogs survived with the transplanted livers which had been perfused for 48 hours with the PHP solution. 3) Successful perfusion of rat small intestine: Lewis rat intestines perfused and preserved for 12 hours with the PHP solution showed a higher survival rate compared with those with Collins or UW solution. 4) Removal of antibodies: By exchange transfusion with a total of 30-60 ml of the PHP solution, a Lewis rat hematocrit lowered to 5% while IgG went down to nil from 8970 mg/dl, IgA to 28 mg/dl from 118 mg/dl and IgM to 190 mg/dl from 897 mg/dl. This technique is expected to be applicable for removal of the naturally existing antibodies in xenotransplantation.

Clonal unresponsiveness results from an interaction between staphylococcal enterotoxin B and T cells expressing unexpected Vβ elements

The ability of staphylococcal toxins to stimulate large numbers of T cells has led to their designation as a superantigen. Previous studies have indicated that activation of T cells bearing particular V beta elements may be responsible for the toxic effects of these bacterial products. However, the widespread expression of functionally similar proteins by unrelated bacterial species suggests the possibility that these products may represent a successful microbial strategy for subversion of the host antibacterial response. We have examined the effects of the staphylococcal enterotoxin B (SEB) on T cell clones that express different V beta elements. We note that SEB stimulates clones bearing previously defined V beta elements to proliferate and to produce cytokines. In addition, we demonstrate that an interaction between SEB and the TCR of clones that express additional V beta elements, including V beta 2 and V beta 6, results in a sterile form of immunological activation. This activation phenotype is characterized by proliferation without detectable cytokine production and is followed by profound immunological unresponsiveness in vitro and in vivo. We propose that reduced levels of antibacterial responses resulting from this form of T cell unresponsiveness may account for the highly conserved expression of superantigens by diverse bacterial species.

Evaluation of a pyridoxylated hemoglobin polyoxyethylene conjugate solution as a perfusate for small intestine preservation

A new type of artificial blood, pyridoxylated hemoglobin-polyoxyethylene conjugate (PHP) solution, (developed by PHP research group of the department of health and welfare of Japan, and produced by Ajinomoto Co., Inc. Tokyo) as an oxygen-carrying component, has been recently devised using hemoglobin obtained from hemolyzed human erythrocytes. Recently, the studies using this solution as a preservation solution were performed in some instances. To examine the mechanism of improved viability using this solution as a preservation solution, we developed a model of orthotopic small intestine transplantation (OIT) in the rat. As a baseline study, we compared parameters of viability of the grafts preserved in Collins and UW solution to those preserved in PHP solution including a survival rate, a serum level total protein and albumin, and a change in body weight after transplantation. In our study, the simple hypothermia storage together with intestinal perfusion preservation with PHP solution was performed. Animals were divided into 6, 12, and 24 hr preservation groups. All of the rats survived after 6 hr preservation following transplantation. However, in 12 hr storage, five of six rats in PHP solution preservation survived and recovery in body weight after grafting was better than those with Collins and UW solution. We conclude that the PHP solution is, therefore, considered to possibly be a more suitable perfusate for small intestine preservation than Collins and UW solution.

Conventional antigen and superantigen may be coupled to distinct and cooperative T-cell activation pathways

CD4+ T cells are equipped to detect two major classes of ligands. Infectious microbial agents, including bacteria and retroviruses, carry a class of proteins termed superantigens that are recognized by the T-cell receptor in association with class II products of the major histocompatibility complex. Proteins expressed by other cells and organisms are processed by macrophages into peptides that are presented to CD4+ T cells by class II molecules. We have examined CD4+ T-cell clones that proliferate vigorously in response both to conventional peptide antigens and to bacterial or retroviral superantigens. The response to peptide antigen is characterized by a rapid and sustained increase in the levels of intracellular free Ca2+ and a vigorous cytokine response. In contrast, the proliferative response of these clones to bacterial or retroviral superantigen is not accompanied by detectable increases in intracellular Ca2+ or by significant cytokine production. Further analysis of T-cell activation indicates that interaction of a single T-cell receptor with the two types of ligand may be coupled to functionally distinct signaling pathways that interact in a synergistic fashion to achieve T-cell activation.

Displacement of apolipophorin III from the surface of low density lipophorin by human apolipoprotein A-I

A hybrid low density lipophorin particle (LDLp) was prepared by incubation with human apolipoprotein (apo) A-I in vitro. ApoA-I associated with LDLp in a concentration dependent, saturable manner which was accompanied by dissociation of apolipophorin III (apoLp-III). The apoA-I hybrid LDLp had the same lipid composition, density and morphology as native LDLp indicating that displacement of apoLp-III by apoA-I did not affect its structural properties. The molar ratio of apoLp-I:apoLp-II:apoLp-III was maximally reduced from 1:1:16 to 1:1:2 in native versus hybrid LDLp with the latter particle binding 7 molecules of apoA-I. The inability of apoA-I to displace the remaining 2 apoLp-III supports the concept that these apoLp-III molecules are not equivalent to the other fourteen. Native and hybrid LDLp particles were both metabolized to high density lipophorin in vivo. The displacement reaction represents a novel method for the production of apolipoprotein hybrids of LDLp and the results indicate that apoA-I has an inherently higher affinity for lipid surfaces than apoLp-III.

Treatment of small cell lung cancer

During a 28-year period, 110 patients with small cell lung cancer were treated at our hospital. Fifty-nine patients received surgery, and 58 patients (including 7 cases after exploratory thoracotomy) received chemotherapy and/or radiotherapy. The 5-year survival rate of the surgically treated group was 17%, while none in the non-surgical group survived for more than 5 years.

Role of lipid transfer particle in transformation of lipophorin in insect oocytes

Oocyte development in Manduca sexta involves the deposition of large amounts of lipoprotein-derived lipid. One source of this lipid is hemolymph high-density lipophorin-adult (HDLp-A) which, upon entry into the oocyte, is transformed into a lipid and apolipophorin III deficient product particle, egg very-high- density lipophorin (VHDLp-E; density = 1.24 g/ml; Kawooya et al. (1988) J. Biol. Chem. 263, 8740-8747). An in vitro model of this transformation has been established using human low-density lipoprotein (LDL) as acceptor of HDLp-A associated lipid in a reaction catalyzed by isolated M. sexta hemolymph lipid transfer particle (LTP). Facilitated vectorial net transfer of lipid from HDLp-A to LDL resulted in formation of a very-high-density lipophorin (VHDLp) product with a density and apolipoprotein content similar to that of VHDLp-E. Lipid was found to comprise 25% of the VHDLp particle mass, whereas over 50% of HDLp-A mass is lipid. Based on these observations it was hypothesized that a lipid transfer factor may be present in M. sexta oocytes and function in the transformation of HDLp-A to VHDLp-E in vivo. Transfer activity was present in the buffer soluble fraction of oocyte homogenates and purification of the active material revealed a catalyst with electrophoretic and immunological properties identical to hemolymph LTP. Incubation of 125I-HDLp-A with an M. sexta oocyte homogenate resulted in transformation of the radiolabeled lipoprotein to a density corresponding to that of VHDLp-E. When the incubation media was preincubated with anti-LTP IgG this conversion was inhibited to a large extent. Inhibition was relieved, however, by addition of exogenous LTP. The results provide the first demonstration of M. sexta LTP in a tissue other than hemolymph and support the concept that LTP-catalyzed lipid transfer plays an integral role in the conversion of HDLp-A to VHDLp-E in vivo.

Increased nasal resistance induced by the pressure-flow technique and its effect on pressure and airflow during speech

Although the validity of the pressure-flow technique has been verified in a number of laboratories, some questions still remain. The purpose of this study was to determine whether the procedures involved in estimating orifice size affect the pressure and airflow variables being measured. Twenty subjects with demonstrated velopharyngeal inadequacy on pressure-flow testing (VPO greater than or equal to 0.10 cm2) were assessed under two contrasting conditions. Subjects were asked to produce (p) in the word "hamper" with a) one nostril occluded by a cork as in pressure-flow testing and b) both nostrils patent. The results indicate that the increased nasal resistance resulting from occlusion of one nostril does not appreciably affect pressure and airflow associated with plosive consonant production in patients with velopharyngeal inadequacy.

[Comparison of Spatholobus suberectus Dum, Euonymus alatus (Thunb.) Sieb. and Eupolyphaga sinensis Walker on regulation of plasma lipid]

The Spatholobus suberectus (SS) of hexue type, the Euonymus alatus (EA) of huoxue type and the Eupolyphaga sinensis (ES) of poxue type were selected and their influence on plasma lipid in the experimental hyperlipidemia quails was observed. The ES could raise plasma HDL-C/TC ratio and increase LCAT activity. The SS could raise plasma HDL2-C/HDL3-C ratio. The effect of EA on plasma HDL-C/TC, HDL2-C/HDL3-C and LCAT levels was between SS and ES. All the three huoxue huayu Chinese drugs could lower plasma HDL3-C level and slow down the progress of atherosclerosis to a certain degree. The above-mentioned results show that certain orders exist between the action range of huoxue huayu drugs and their effect on regulating plasma lipid.

Impact of Phase I Pew National Dental education Program on U.S. schools of dental medicine

This paper presents the results of four telephone surveys conducted by the Leonard Davis Institute of Health Economics (LDI), University of Pennsylvania, as part of its evaluation of the Pew National Dental Education Program (PNDEP), a five year, +4F8.7 million program established by The Pew Charitable Trusts to help dental schools respond to the changing health care environment. The four annual surveys were conducted between 1985 and 1988. The interviews were conducted with the deans from nearly all dental schools operating in the United States at the time of study or the principal investigators of the schools funded under Phase I and Phase II PNDEP grants. Their purpose was to determine the level of each school's involvement in PNDEP and in specific strategic planning activities, as well as to evaluate the impact of the Pew Program on both the individual schools and dental education nationwide. All systematic differences between schools funded (FD) PNDEP and those not funded (NFD) were examined. Overall, schools gained a better understanding of their environment. Schools also reported increased participation in and commitment to planning among their different constituencies (e.g., faculty, administration, students, alumni). By the end of Phase I, more PNDEP Phase I funded schools reported being involved in implementing strategic plans. Funded schools also were more likely to report PNDEP increased their understanding of strategic planning, improved communication, and helped encourage the emergence of new leaders.

Microsurgical fertilization and teratozoospermia

Semen parameters were correlated with the outcome of partial zona dissection (PZD) in 42 couples with male factor infertility. Although fertilization rates were reduced, 12% of the embryos implanted following replacement. Spermatozoa from teratozoospermic sperm populations were able to fuse with oocytes following zona penetration through the artificial gaps. PZD followed by insemination with less than 5% normal spermatozoa led to 20 embryos which, upon replacement, did not implant. Motility and sperm count were not clearly correlated with the outcome of PZD and are therefore less useful indicators for patient selection. Teratozoospermic patients who previously failed to fertilize were compared to a group of similar patients who had not attempted IVF before. Although fertilization was significantly improved in first-time patients, 41% of the patients whose spermatozoa were initially unable to fertilize had at least one embryo when PZD was performed. Several pregnancies were established in this group. Subzonal sperm insertion (SZI) and PZD were compared in 19 patients using sibling oocytes. A significant fraction of spermatozoa from infertile men were able to fuse with the oolemma when directly inserted into the perivitelline area. Using a sucrose solution to shrink the ooplasm, only 1% of the oocytes were damaged during SZI. Monospermic fertilization rates following PZD and SZI were 15 and 16%, respectively. Both micromanipulation methods were successful in most patients. However, in two small groups of patients, only one technique resulted in fertilization.