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J Rapp

Publications and source records attributed to J Rapp.

At least 37 records · Page 2Linked to original sources
PubMed1997

Protein-lipid interaction on the surface of a rigid gas-permeable contact lens in vitro.

PURPOSE: To investigate the mechanism of protein-lipid interactions responsible for biofilm formation on the surface of rigid gas-permeable contact lenses in vitro. METHODS: Two types of new, never-worn rigid gas-permeable contact lenses (siloxanyl alkyl acrylate and fluorosiloxanyl alkyl acrylate) were individually incubated in a protein only, lipid only, or combination protein-lipid artificial tear solution for 24 h at 37 degrees C with constant stirring. Deposited lipids were removed with a methanol based extraction procedure, separated using high performance thin layer chromatography and quantitatively analyzed densitometrically. Deposited proteins were extracted with 4M urea, separated using gel electrophoresis and quantitatively analyzed densitometrically. RESULTS: Lipid deposition on rigid gas-permeable contact lenses is dependent on lens matrix hydrophobicity while protein deposition is minimal and not material-dependent. The presence of lipid in the artificial tear solution enhances protein deposition on both types of rigid gas-permeable materials examined. The presence of protein in the artificial tear solution decreases lipid deposition on a siloxanyl alkyl acrylate lens. CONCLUSIONS: The hydrophobic nature of rigid gas-permeable contact lenses causes them to be more prone to lipid than to protein deposition. When both types of molecule are present in an artificial tear solution, the hydrophobic sites of the lipid molecules are attracted to the lens matrix while the more hydrophilic sites are repelled by the matrix and, thereby, exposed to the aqueous surroundings. Thus, lipid binding to rigid gas-permeable contact lenses reduces the hydrophobicity of the lens surface allowing protein to bind. The bound deposited hydrophilic protein then alters subsequent binding of both protein and lipid.

Contact Lenses↗
PubMed1997

Protein-lipid interaction on the surface of a hydrophilic contact lens in vitro.

PURPOSE: To investigate the mechanism of protein-lipid interactions responsible for biofilm formation on the surface of hydrophilic contact lenses in vitro. METHODS: New, never-worn hydrophilic contact lenses were individually incubated in a protein-only, lipid-only, or combination protein-lipid artificial tear solution for 24 hours at 37 degrees C with constant stirring. Deposited lipids were removed with a methanol based extraction procedure, separated using high-performance, thin layer chromatography and quantitatively analyzed densitometrically. Deposited proteins were extracted with 4M urea, separated using gel electrophoresis and quantitatively analyzed densitometrically. RESULTS: The presence of protein in the artificial tear solution has a profound effect on the nature of lipid deposition for each group of hydrophilic lens, whereas the presence of lipid has a significant effect on the nature of protein deposition for only a group IV lens. In addition, the presence of lipid deposits on a group IV lens decreases the adsorption of lysozyme, while the presence of protein deposits reduces the amount of total lipid adhering to a group II lens. CONCLUSIONS: Protein adsorption on a group IV lens renders the lens surface less hydrophilic and, thereby, more susceptible to lipid deposition, which in turn increases surface hydrophobicity and inhibits additional protein deposition. For a group II lens, positively charged protein competes with and replaces some of the polar lipids attached to the lens. Thus, the interaction of protein and lipid on a lens surface most prone to a particular contaminant apparently makes it less likely for that contaminant to bind.

Adsorption↗
PubMed1994

Lipid deposits on hydrophilic and rigid gas permeable contact lenses.

Never-worn hydrophilic contact lenses (from each of the four FDA-classified groups) and rigid gas permeable (RGP) lenses were individually incubated for 24 hours at 37 degrees C with constant stirring in a mixture of 992 microL of 0.9% saline and 8 microL of a 1:1 chloroform:methanol solution of lipids (20 mg each of cholesterol, free fatty acid, triglyceride, fatty acid methyl ester, and cholesteryl ester, representative of lipids commonly found in the tear film). The lipid material deposited onto each lens was then extracted and its components separated using high performance thin layer chromatography. The chromatograms were analyzed by densitometry. Results indicate significant lipid deposition onto all lens types, with the siloxanyl alkyl acrylate RGP-type lenses accumulating two to three times as much total lipid as any of the other lenses. This suggests that hydrophobic RGP lenses, which also have lipophilic character, are most prone to develop lipid deposits. Among the hydrophilic lenses, nonionic polymer matrices and higher water content tended to increase lipid deposition.

Chromatography, Thin Layer↗
PubMed1994

Monanema martini in its murid hosts: microfiladermia related to infective larvae and adult filariae.

The microfiladermia of Monanema martini was studied in two natural murid hosts, Lemniscomys striatus and Arvicanthis niloticus, with 137 and 39 rodents respectively inoculated once, twice or several times. Microfilarial densities (mf/mm2) were measured at the ear pinna every three months. Almost all the rodents developed a microfiladermia. When L. striatus rodents were inoculated once with 30, 80, or 400 infective larvae, microfiladermia increased (peaks of 108, 148, 174 mf/mm2 respectively, at six to nine months p.i.); this fits with the fact that, in this filaria-host pair, the number of adult filariae is proportional to the number of inoculated larvae, and remains at a constant level for more than eight months. Nevertheless microfiladermia was limited, especially during the peak, showing the complexity of its regulatory mechanisms. Several low doses over one year, resulting in 145 L3, increased the microfiladermia at the same level than one dose of 400 larvae; the recovery rate of the larvae was reduced but the total number of filariae recovered was increased. A. niloticus, from which the filarial strain originates, showed a much lower microfiladermia than L. striatus (7 mf/mm2 with 80 larvae, at six months p.i.). This was due to a smaller recovery rate of the infective larvae in this host and, overall, to a reduced fertility of the female worms and a shorter lifetime of adult filariae. However, repeated inoculations increased the microfiladermia (32 mf/mm2), due to the constant presence of small numbers of young filariae producing microfilariae. It is to be noted that the two biological systems presented by M. martini in L. striatus and A. niloticus correspond to the two types of ocular pathology described in a recent opthalmological study, chorioretinal atrophy and keratitis respectively.

Animals↗
PubMed1993

Protein-free culture of Vero cells: a substrate for replication of human pathogenic viruses.

A protein-free chemically defined medium designated PFEK-1 was developed for culture of VERO cells on polyvinyl formal (PVF) culture surface without serum or other macromolecular supplements. VERO cells proliferated in PFEK-1 medium on PVF surface to a similar extent as cells in serum-supplemented medium without previous adaptation from serum-containing conditions. The protein-free culture infected with coxsackievirus B4, herpes simplex virus types 1 and 2, measles virus and poliovirus types 1, 2 and 3 developed viral titers comparable to those found in conventionally grown cells. The results demonstrated that VERO cells in protein-free culture provide a sensitive substrate for the production of human pathogenic viruses which are not contaminated by serum or other protein factors usually added to a culture medium.

Animals↗
PubMed1993

The efficacy of hydrophilic contact lens cleaning systems in removing protein deposits.

New, never-worn, individual hydrophilic contact lenses were incubated in an artificial tear solution (containing lysozyme, albumin, lactoferrin, and glycoprotein) for 24 hours at 37 degrees C with constant stirring. These lenses were then cleaned following the manufacturer's instructions with one of six commercial cleaning systems: AOSEPT, CONSEPT, Oxysept, ReNu, Opti-Free and thermal disinfection in conjunction with the Allergan Enzymatic Contact Lens Cleaner. The protein remaining on each lens after cleaning was removed and then quantified by the Bio-Rad Protein Assay. High resolution gel electrophoresis was used to assess the individual protein profile patterns. We found that only one-third to one-half of the protein deposited on a lens is removed by the above cleaning systems. Of the proteins in the artificial tear solution only lysozyme is removed by cleaning, while lactoferrin, albumin, and glycoprotein tend to remain on the lens. Since many of the complications experienced by contact lens wearers are thought to be related to protein deposits on their lenses, our results suggest the need for more effective contact lens cleaning solutions.

Albumins↗
PubMed1990

Chlamydia trachomatis infection of human fallopian tube organ cultures.

The pathogenic events that precede Chlamydia trachomatis salpingitis in the human fallopian tube have not been fully described. We used a model of human fallopian tubes in organ culture (HFTOC) infected with strain E/UW-5/CX of C. trachomatis to study these events. The model supported sustained C. trachomatis infection as demonstrated by recovery of viable C. trachomatis from medium and tissue over 5-7 d. However, the level of infectivity was low. Maximal infection occurred at 72 h after initial inoculation. In contrast to gonococcal infection of the HFTOC, C. trachomatis did not damage overall ciliary function of HFTOC. However, a local direct cytotoxic effect characterized by loss of microvilli and disruption of cell junctions was noted when multiple chlamydial elementary bodies attached to mucosal cells. Beginning at 24 h, and continuing throughout the course of C. trachomatis infection of HFTOC, ruptured epithelial cells releasing elementary bodies were noted. Chlamydial inclusions were seen in the mucosa by 72 h in approximately 6% of both ciliated and nonciliated epithelial cells. Mucosal inclusions contained all forms of the C. trachomatis developmental cycle. These data suggest that factors present in the human fallopian tube may limit susceptibility to chlamydial infection but support the use of the HFTOC model in the study of the pathogenesis of C. trachomatis salpingitis.

Chlamydia Infections↗
PubMed1989

Anaphylactoid reactions to vascular graft material presenting with vasodilation and subsequent disseminated intravascular coagulation.

This report describes five patients who had immediate adverse reactions following placement of a vascular graft. All had unusually persistent decreases in systemic vascular resistance, and four of these patients had bleeding as an early manifestation of this reaction. In two of three patients in whom the graft was replaced, uneventful recovery followed. Both patients in whom the graft was not replaced died. Blood samples from two of the patients demonstrated activation of complement and of the kinin system, whereas control patients did not demonstrate increased levels of activation products from these cascade systems. Recognition of this syndrome is important to patient survival, which appears to depend on rapid replacement of the graft.

Aged↗
PubMed1988

Adrenal renin: a possible local hormonal regulator of aldosterone production.

The complete renin-angiotensin system is present in the adrenal cortex: prorenin, renin, angiotensinogen, angiotensin I and II, and converting enzyme. Most of the renin found is probably synthesized there since the renin concentration increases after nephrectomy, and the mRNA for renin is present. The renin-angiotensin system has the highest activity in the zona glomerulosa cells, the site of aldosterone formation. A low-sodium diet or a high-potassium diet, or nephrectomy markedly increases the adrenal renin concentration in the zona glomerulosa cells without any effect on the fasciculata-medullary cells. There is a close correlation between adrenal renin and aldosterone production. The adrenal renin angiotensin system may be a local regulator of aldosterone production.

Adrenal Glands↗
PubMed1986

[Regulation of V1-vasopressinergic receptors in the rat].

Using tritiated vasopressin, specific binding sites for vasopressin were identified on splenic membranes of Sprague-Dawley rats. One class of high affinity receptors was characterized with an equilibrium dissociation constant of 1.91 +/- 0.16 nM and a maximal binding capacity of 110 +/- 11 fmol/mg of protein. Several experimental evidences suggest that these receptors belong to the V1-vascular type: The affinity of 8 vasopressin agonists for the receptor is correlated to their vasopressor activity in vivo whereas no such relationship exists when their antidiuretic activity is considered. The affinity of 5 vasopressin antagonists for the receptor is correlated to their antivasopressor activity in vivo whereas no such relationship exists when their antidiuretic activity is considered. Vasopressin does not stimulate cyclic AMP production of splenic membranes. The regulation of these receptors was studied in sodium-sensitive (S) and sodium-resistant animals (R) of Dahl receiving a special diet (0.1 or 8% NaCl) for two weeks. In both strains of animals, the number of receptors is smaller in R animals than in S animals, whatever the diet ingested. Splenic membranes of rat bear easily accessible V1-vasopressinergic receptors. These receptors are modulated by sodium intake and the difference in receptor number between S and R rats could explain the increased vascular reactivity of S animals to vasopressin.

Animals↗