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Biomedical subjects

P Klein

Publications and source records attributed to P Klein.

At least 181 records · Page 10Linked to original sources
PubMed1987

Potential acuity meter for predicting postoperative visual acuity in penetrating keratoplasty. A new method using a hard contact lens.

An irregular corneal surface degrades the optical transmission and limits the effectiveness of the potential acuity meter (PAM) in predicting post-keratoplasty visual acuity. The authors investigated the efficacy of using a temporarily placed hard contact lens to neutralize surface irregularities in conjunction with the PAM in predicting post-keratoplasty visual acuity. A prospective evaluation was performed on 40 keratoplasty patients with a mean follow-up of 10.4 months. Of 27 patients with corneas clear enough to permit them to read letters on the PAM chart, 17 (63%) had very accurately predicted visual acuities by this new method, compared to only eight patients (30%) with the PAM alone. Three patients had predicted visions better than final vision, but this was due to a concurrent cataract in two cases and chronic cystoid macular edema (CME) in the third case. This study indicates that temporarily placing a hard contact lens for use with the PAM can increase its accuracy in predicting final visual acuity after penetrating keratoplasty.

Adult↗
PubMed1987

Avoiding early failure of tibial prosthetic bypass grafts.

In a series of 97 tibial reconstructions using PTFE bypass grafts the value of perioperative anticoagulation was studied. Acetylsalicylic acid as well as low-dose heparin treatment resulted in a high graft failure rate during the first postoperative days (42%). Patency could be restored in half of the cases by simple thrombectomy. When heparin was given at a dose of 1000 I.U. per hour for two days the graft failure rate was 14%. Only one out of eight thrombosed grafts could be re-opened by thrombectomy. Long-term patency, however, was similar in both groups. We conclude that perioperative heparin treatment is a suitable method to avoid unnecessary thrombectomies of long prosthetic bypass grafts.

Blood Vessel Prosthesis↗
PubMed1987

Structural relatedness of lysis proteins from colicinogenic plasmids and icosahedral coliphages.

The host-lysis-inducing functions of phi X174 protein E and MS2 protein L were recently shown to reside on the N-terminal and C-terminal halves of the two respective lysis proteins. In the present study it is shown that the small lysis proteins encoded in various colicinogenic plasmids share local sequence similarities and certain structural characteristics with the essential peptides of their coliphage-coded counterparts. Despite their dissimilar sizes and origins, it is suggested that the colicinogenic lysis proteins are functionally analogous and evolutionarily related to those of icosahedral single-stranded DNA and RNA phages.

Amino Acid Sequence↗
PubMed1987

Non-infectious corneal vascularization.

A 26-year-old white female presented with a complaint of tearing and light sensitivity of several weeks duration. Examination revealed a translucent foreign body embedded in the temporal aspect of the right cornea. The fragment embedded in the cornea produced localized corneal inflammation and vascularization. The foreign body was removed and the eye was pressure patched overnight. One day after removal of the foreign body, the eye was white and quiet and the patient was comfortable. This case report represents a unique in vivo observation into the pathogenesis of non-infectious corneal vascularization.

Adult↗
PubMed1986

Prediction of protein structural class by discriminant analysis.

Protein structural class--alpha, beta, mixed (alpha/beta or alpha + beta), irregular--can be predicted from the amino acid sequence by discriminant analysis. Discrimination is based on distributions, in the classes, of vectors of attributes characterizing the sequences. In this paper, two sets of attributes and two methods of estimating their distributions are compared using more than 100 proteins from the Protein Data Bank. The best results were obtained when canonical variates of the frequencies of occurrence of 20 amino acids and non-parametric estimates of their distributions were used. Three variates are sufficient to allocate proteins to one of four classes with 83% reliability (estimated by cross-validation) and four variates allowed allocation to one of five classes with 78% reliability.

Amino Acid Sequence↗
PubMed1986

[Procedures in fulminant courses of necrotizing enterocolitis].

14/42 neonates suffering from N.E.C. developed the clinical stage III (intestinal necrosis, septicemia) and/or IV (intestinal perforation, peritonitis) within 24-48 h ("fulminant" course). 2/14 deteriorated dramatically and died before operation. In 12/14 cases, the general condition could be improved and immediate laparotomy was performed (2/12 died). Management and factors affecting prognosis are discussed. Following surgery, there was no significant difference in survival rates between "fulminant" and protracted course N.E.C.

Combined Modality Therapy↗
PubMed1986

Ocular manifestations of Fabry's disease.

A 52-year-old black female teacher's aide presented for an eye examination with a complaint of progressively worsening vision, stinging and burning of the eyes, and occasional foreign body sensation. Examination revealed a dry eye syndrome and corneal dystrophy consistent with Fabry's disease, a cardiovascular disease with significant systemic as well as ocular findings. The patient was treated for the acute corneal symptoms and closely followed for progression of the dystrophic corneal changes.

Acute Disease↗
PubMed1985

The detection and classification of membrane-spanning proteins.

Discriminant analysis can be used to precisely classify membrane proteins as integral or peripheral and to estimate the odds that the classification is correct. Specifically, using 102 membrane proteins from the National Biomedical Research Foundation (NBRF) database we find that discrimination between integral and peripheral membrane proteins can be achieved with 99% reliability. Hydrophobic segments of integral membrane proteins can also be distinguished from interior segments of globular soluble proteins with better than 95% reliability. We also propose a procedure for determining boundaries of membrane-spanning segments and apply it to several integral membrane proteins. For the limited data available (such as on transplantation antigens), the residues at the boundaries of a membrane-spanning segment are predictable to within the error inherent in the concept of boundary. As a specific indication of resolution, seven membrane-spanning segments of bacteriorhodopsin are resolved with no information other than sequence, and the predicted boundary residues agree with the experimental data on proteolytic cleavage sites. Several definitive but yet to be tested predictions are also made, and the relation to other predictive methods is briefly discussed. A computer program in FORTRAN for prediction of membrane-spanning segments is available from the authors.

Animals↗
PubMed1985

Identification and cyclic AMP-induced modification of the cyclic AMP receptor in Dictyostelium discoideum.

We have recently identified a cell surface cAMP-binding protein by specific photoaffinity labeling of intact Dictyostelium discoideum cells with 8-N3-[32P] cAMP. The major photolabeled protein appears as a doublet (Mr = 40,000-43,000) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiography. In this study, the doublet is shown to have the characteristics of the cAMP receptor responsible for chemotaxis and cAMP signaling. Both specific photoaffinity labeling of the doublet and binding of 8-N3-[32P]cAMP are saturable (KD = 0.3 microM), the levels of both peak at 5 h, and both are inhibited by cAMP and several cAMP analogs in the same order of potency and with K1 values similar to those measured for inhibition of [3H]cAMP binding. When cAMP-binding activity was partially purified (40-fold) and then photoaffinity labeled, the same bands (Mr = 40,000-43,000) were observed. The relative intensities of the upper and lower bands of the doublet alternated at the same frequency as the spontaneous oscillations in cAMP synthesis. When oscillations were suppressed, the lower band of the doublet predominated. Following addition of cAMP, the relative intensity gradually shifted to the upper band. When cAMP was removed, there was a gradual restoration of the lower band form. We propose that the lower band form of the receptor activates chemotaxis and cAMP signaling and that the upper band form does not. This reversible receptor modification may then be the mechanism of adaptation, the process by which the physiological responses cease to be stimulated by persistent cAMP. Several developmentally regulated genes in D. discoideum have been reported to be induced or suppressed by pulses of cAMP (adaptive regulation) and others by continuous cAMP (nonadaptive regulation). These observations may be explained by the receptor modification reported here if the two forms of the receptor, which bind cAMP with the same affinity, independently influence gene expression.

Affinity Labels↗
PubMed1985

[Bologna's treatment method for stress urinary incontinence. An interesting technic in large cystoceles].

The authors report a series of 25 operations using the Bologna technic in which 20 cases were examined with bladder function tests before and after surgery. This technic has curative results for vesical hernia or cystocele and urinary incontinence. In all but one case the abdominal pressure transmission defect to the upper urethra was corrected without deterioration of maximal urethral pressure.

Aged↗
PubMed1984

Specific photoaffinity labeling of the cAMP surface receptor in Dictyostelium discoideum.

The recent observation that ammonium sulfate stabilizes cell-surface [3H]cyclic AMP binding in Dictyostelium discoideum (Van Haastert, P., and Kien, E. (1983) J. Biol. Chem. 258, 9636-9642) led us to attempt to identify the surface cAMP receptor by photoaffinity labeling with 8-azido-[32P]cAMP using this stabilization technique. 8-azido-[32P]cAMP specifically labeled a polypeptide which migrates as a closely spaced doublet (Mr = 40,000 to 43,000) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Greater than 60% of the labeled polypeptide was found associated with membranes. This protein was distinguished from the cytosolic regulatory subunit of the cAMP-dependent protein kinase (Mr = 41,000) by differences in developmental regulation, specificity, and subcellular localization. No kinase regulatory subunit was detected in membranes by western blot analysis. Our preliminary observations show that labeling of this doublet correlates closely with cAMP-binding activity, suggesting that it is the surface receptor which mediates chemotaxis and cAMP signaling.

Azides↗
PubMed1984

Prediction of protein function from sequence properties. Discriminant analysis of a data base.

The protein superfamilies in the National Biomedical Research Foundation sequence data base cluster into six groups that can be distinguished on the basis of four variables characterizing amino acid composition and local sequence properties. The variables are average hydrophobicity, net charge, sequence length and periodic variation in hydrophobic residues along the chain. The clusters they distinguish are: globins; chromosomal proteins; contractile system proteins and respiratory proteins other than cytochromes; enzyme inhibitors and toxins; enzymes except hydrolases; and all other proteins. The overall probability of correctly allocating a given protein to one of these functional groups is 0.76, with the allocation reliability being highest for globins (0.97) and for chromosomal proteins (0.93).

Amino Acid Sequence↗