Louisiana's criteria of eligibility for occupational therapy services in the public school system.

Since the enactment of the Education for All Handicapped Children Act of 1975 (Public Law 94-142), occupational therapists in the public schools have been responsible for determining the occupational therapy needs of special education students. In Louisiana, therapists and special educators, in cooperation with the Louisiana Department of Education, have developed the criteria of eligibility for occupational therapy. These criteria do not alter the descriptive standards established in Public Law 94-142; instead, they provide an objective method for the selection of students in need of occupational therapy. The criteria, which have been revised and refined since 1981, were adopted recently by the Louisiana Board of Elementary and Secondary Education. This paper presents these criteria and examples of their implementation.

Extrachromosomal DNA transformation of Caenorhabditis elegans.

DNA was introduced into the germ line of the nematode Caenorhabditis elegans by microinjection. Approximately 10% of the injected worms gave rise to transformed progeny. Upon injection, supercoiled molecules formed a high-molecular-weight array predominantly composed of tandem repeats of the injected sequence. Injected linear molecules formed both tandem and inverted repeats as if they had ligated to each other. No worm DNA sequences were required in the injected plasmid for the formation of these high-molecular-weight arrays. Surprisingly, these high-molecular-weight arrays were extrachromosomal and heritable. On average 50% of the progeny of a transformed hermaphrodite still carried the exogenous sequences. In situ hybridization experiments demonstrated that approximately half of the transformed animals carried foreign DNA in all of their cells; the remainder were mosaic animals in which some cells contained the exogenous sequences while others carried no detectable foreign DNA. The presence of mosaic and nonmosaic nematodes in transformed populations may permit detailed analysis of the expression and function of C. elegans genes.

Validation of infrared spectroscopy for assessment of vinyl polymers of bile-pigment gallstones.

The i.r. spectra of bilirubin isomers that differ in number and position of vinyl groups were examined to verify the assignment of the 988 cm-1 peak of bilirubin (991 cm-1 peak in calcium bilirubinate) to its pendant vinyl groups. There were only small changes in this peak with changes in position of vinyl groups (exo-2- and -18-vinyl versus endo-3- and -17-vinyl), but progressive loss of peaks in this region was observed when vinyl groups were reduced to ethyl groups (dihydrobilirubin and mesobilirubin). Methylvinylmaleimide, a monopyrrole derived from the outer (A and D) rings of bilirubin, has a pendant vinyl group and exhibits a prominent peak at 986 cm-1, but haematinic acid methyl ester derived from the inner (B and C) rings has no vinyl group and shows no peak near 988 cm-1. These observations verify the assignment of the 988 cm-1 peak of bilirubin to its pendant vinyl groups. This supports our previous proposal that a decrease in the peak at 985-995 cm-1 in the i.r. spectra of pigment gallstones, as compared with unconjugated bilirubin or calcium bilirubinate, indicates a consumption of vinyl groups in the process of formation of the polymer in the pigment stones.

Polymer networks in pigment and cholesterol gallstones assessed by equilibrium swelling and infrared spectroscopy.

Sixty-five gallstones were assessed for content of network polymer by equilibrium swelling and infrared spectroscopy. All types of pigment gallstones exhibited swelling in aqueous buffers, indicating network polymer content, but swelling was greatest in black pigment gallstones. Gallstones composed principally of cholesterol did not swell. Swelling increased with increasing pH values from 6 to 10.5, suggesting that titratable carboxyl side chains of the pigment were intact. Swelling increased in the presence of 10 mM ethylenediaminetetraacetic acid, indicating that calcium ions provided secondary crosslinks in the network. In all types of pigment gallstones, the equilibrium swelling ratio at the maximum (pH = 10.5) was correlated inversely with the proportion of intact vinyl groups in the pigment assessed by infrared spectroscopy. This suggests that pigment vinyl groups are consumed in forming the covalent crosslinks of the polymer network. A weaker direct correlation between equilibrium swelling ratio and the percentage of unmeasured residue in the gallstones suggested that this residue may also have contributed to the swelling. The high content of cross-linked network polymer in black pigment gallstones renders their therapeutic dissolution improbable by physicochemical means.

Interactions between segmented polyurethane surfaces and the plasma protein fibrinogen.

Surfaces of a segmented polyurethane were varied by casting on poly(ethylene terephthalate) (PET) and glass substrates, and were characterized through infrared-attenuated total-reflection spectroscopy (ATR). Surfaces cast on glass substrates showed a higher content of polyether segments, whereas those cast on PET contained a higher relative concentration of aromatic segments. Adsorption, and possible conformational changes of fibrinogen, were found to be more substantial on polymer surfaces having a higher content of polyether segments. It is concluded that the relatively good blood compatibility of segmented polyurethanes is partly due to the presence of peptide-like bonds on aromatic segments.

Poly(glycolic acid) sutures in canine vascular anastomoses.

Poly(glycolic acid) (Dexon; Davis and Geck Company) canine vascular anastomoses between aorta and synthetic grafts and between severed femoral vessels were compared with comparable anastomoses made with Teflon-coated Dacron (Tevdek; The Deknatel Company) with respect to clinical performance, morphologic characteristics, and tensile strength. While the Dexon anastomoses performed well and were morphologically superior to Tevdek, their tensile strength was significantly lower. Implications of these findings for vascular wound healing are discussed.

In vitro testing of surface thrombogenicity using the thrombelastograph.

Synthetic surfaces can be assessed for their ability to promote or inhibit whole blood coagulation with improved accuracy using a new protocol developed for the Thrombelastograph instrument. Results obtained from the analysis of the hydrodynamic state of blood clotting in Thrombelastograph chambers have enabled a quantitative interpretation of the output of this instrument to be made. The thrombogenic properties of a segmented polyurethane and a polydimethyl siloxane are compared with a preparation of reconstituted elastin. It is seen that a four-fold delay in clotting time is exhibited by reconstituted elastin when it is compared with other biomedical synthetic materials tested.

Epitaxial crystallization of poly (γ-benzyl L-glutamate) on alkali halide single crystals.

Single crystals of poly(γ-benzyl L-glutamate) were formed by epitaxial crystallization from solution in mesitylene on NaCl, KI, and KCl (001) cleavage faces. From electron microscopy and diffraction studies, the structure of these overgrowths was determined to be that of lamellae containing chain-folded α-helical macromolecules. The usual type of crystal perfection, that of ordered helix axes and disordered side groups, was exhibited by this synthetic polypeptide. Unique orientation regimes were observed with each substrate.