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PubMedDate not supplied

Computer optimization of enteral hyperalimentation.

A computer program has been developed to allow the generation of written orders for the logical progression of enteral hyperalimentation by the technique of continuous nasogastric infusion. Data required for entry include name, age, sex, height, usual and current weights, degree of stress, and if indicated, restrictions of nitrogen, fluids, sodium and potassium. A specific formulation may be requested, or the computer will pick a single nutrient solution or combination of two solutions that will best meet the requested constraints. Output includes entered data with English and Metric interconversion, surface area, and estimates of basal energy expenditure, protein wastage, protein and caloric requirements. If requested, daily orders are written to include a reasonable progression of infusion rates and concentrations of the solutions(s). Daily values are printed for the total amounts to be infused of fluid, calories, protein, sodium, potassium, and mOsm. The programs have been demonstrated to run in either on-line or batch mode. The system is easily accessible by physician, dietician, nurse, or other interested professionals.

Adult↗
PubMed1978

[Study of structural changes in muscle fiber contractile proteins using polarization ultraviolet fluorescent microscopy. IV. Several features of the conformational changes in F-actin during muscle fiber relaxation].

Using the polarized ultraviolet fluorescent microscopy in the presence of a fluorescence quencher (acrylamide, NO3-) it has been shown that actin tryptophanyls are oriented with their short axes perpendicular to the long axis of the thin filament. Fluorophores in hardly accessible sites of the macromolecule have a more pronounced anisotrophy of orientation in comparison with those in the protein sites easily available by a fluorescence quencher. During the muscle fiber relaxation, conformational changes of F-actin take place which embrace seemingly the sites of subunits, close to the surface of macromolecule, and make difficult the penetration of univalent ions and neutral molecules deep into the protein macromolecule. Some connection between conformational changes of the surface areas of F-actin subunits and the actin incapability of combining with HMM in the presence of ATP is assumed.

Acrylamides↗
PubMed1978

Salmonella pollution of surface waters.

Surface waters in 14 selected sites were examined for the presence of salmonella using modified Moore's swabs. The sites included an upland impounding reservoir, 3 rivers and 10 streams within Lancashire and Cheshire, selected because of their accessibility to farm livestock. Salmonellas were isolated from 22 out of the 57 swabs examined representing 10 sites. The probable source of pollution was shown to be sewage or farm effluent and an examination of sites over a wider area may be expected to produce similar results. The significance of these findings is discussed in relation to the epidemiology of salmonella infections and the possible disinfection of effluent discharges.

England↗
PubMed1979

A pharmacological approach to the structure of sodium channels in myelinated axons.

Figure 6 summarizes the present state of our knowledge on the sodium channel in myelinated nerve fibers. Two sites have been discussed in detail: a metal cation binding site accessible by tetrodotoxin and saxitoxin from the outside surface only; and a second site accessible from the inside surface with which local anesthetics combine. Hydrogen ions gain access to this region of the sodium channel (and hence determine the relative local concentration of protonated drug) more readily from the extracellular fluid than from the axoplasm (Schwarz et al 1977). In addition, a variety of other sites have been mentioned, binding of drugs to which alters selectively the kinetics of opening and closing of the h and m gates. In myelinated nerve fibers these channels are packed tightly on the nodal membrane. The highest estimate for the sodium channel density in the mammalian node is 10,000 micron2. A re-evaluation of the effective nodal area, however, might reduce this value to 3000-5000/micron 2. This would still leave the nodal membrane rather crowded with sodium channels. Furthermore, the channel density would still be greater than the density of particles, sometimes believed to be sodium channels seen in freeze fracture studies (Rosenbluth 1976). One possibility for resolving this problem is that the units detected by X-ray inactivation (Levinson & Ellory 1973), and those seen in freeze-fracture studies (Rosenbluth 1976) represent not single sodium channels but groups of three. Catterall & Morrow (1978) in a comparison of the binding of saxitoxin and Leiurus sculpturatus scorpion toxin venom have concluded that there are three saxitoxin binding sites for each scorpion toxin binding site. On this basis, three saxitoxin molecules might act to block independently each of the three openings of the channels; while the the conformational change produced by the scorpion venom molecule would affect the inactivation process of all three channels.

Aconitine↗
PubMed1978

Sealing quality of a temporary filling material.

Endodontic access cavities were prepared in forty extracted human teeth. The access cavities were obturated with Cavit and tested for leakage with methylene blue. The data suggested that at least a 3.5 mm. thickness of Cavit should be used in order to prevent leakage. Examination under the scanning electron microscope showed areas in which the constituents of Cavit were improperly mixed, which may lead to increased penetration.

Dental Cavity Preparation↗
PubMed1977

Adaptation of marrow sinus wall to fluctuation in the rate of cell delivery: studies in rabbits after blood-letting.

The extent of marrow sinus wall coverage by perisinal adventitial cells was measured before and after removing 25% of the calculated blood volume in rabbits. A marked reduction in the area covered by adventitial cells was recorded coinciding with the early reticulocyte response to phlebotomy. In control animals, only scattered microfilaments were occasionally observed in the cytoplasmic process of adventitial cells. After phlebotomy, these filaments were more frequently observed and appeared as band-like structures, raising the possibility of an active role for perisinal adventitial cells in response to fluctuations in the magnitude of cell traffic. Perisinal adventitial cells may, therefore, translate the body's demand for cell delivery by regulating the rate of transmural cell migration from the marrow. Such an adaptive mechanism may depend on the incompleteness of the adventitial layer of the sinus wall and the absence of endothelial-adventitial cell junctions, permitting separation of the two layers of the wall, so that the reticulocyte can gain access to more endothelial surface and the pores.

Adaptation, Physiological↗
PubMed1977

Rapid accumulation of cholesterol in serum, liver and aorta of Japanese quail.

Five-week-old, male, Japanese quail (Coturnix coturnix japonica) were given ad lib. access to either a glucose-soybean meal diet with 10% fat and 1% cholesterol (inducer) diet, or a corn-soybean meal (control) diet for 10 weeks. At the beginning of the experiment, and at two week intervals thereafter, quail from each treatment were killed, and the cholesterol concentrations of serum, aorta, and liver, as well as the extent of lipid accumulation in the intima of the aortas were determined. The cholesterol concentration of the serum, aorta, and liver of the control birds remained constant throughout the experiment, while the cholesterol concentration of these organs from birds fed the inducer diet were markedly elevated. At the conclusion of the experiment, the cholesterol concentrations of the serum and liver of birds fed the inducer diet were 6.7 and 14.4 times greater, respectively, than those from the control-fed birds. Approximately 45% of the aortas from the birds fed the inducer diet exhibited moderate to severe (greater than 25% of surface area covered) lipid accumulations at 10 weeks. The rate of cholesterol accumulation appeared to be more rapid than has been reported previously for this species.

Animals↗
PubMed1975

Studies of glutamate dehydrogenase: analysis of functional areas and functional groups.

1. It is shown by limited tryptic digestion of beef liver glutamate dehydrogenase under native conditions that the amino terminus of the polypeptide chain is located at the surface of the molecule. End-group analysis after trypsin treatment yields aspartic acid as the new N-terminal amino acid while the C-terminal threonine remains unchanged. 2. NADH, especially in the presence of 2-oxoglutarate, protects the enzyme against tryptic degradation. In the absence of the coenzyme, glutamate dehydrogenase is rapidly inactivated. 3. The regulatory effects of ADP and GTP are only slightly altered by trypsin. A small shift of the pH dependence of the activation by ADP is observed. 4. The quaternary structure of the unimer of the enzyme is not affected by limited tryptic digestion indicating that the N-terminal part of the polypeptide chain is not located in the contact domains between the polypeptide chains. The association of the hexamer to large associated particles is reduced but not abolished. 5. It is shown by treatment of the enzyme with iodo[2(-14)C]acetic acid as well as with Ellman's reagent that the six - SH groups of the polypeptide chain are buried and not accessible to these reagents in phosphate buffer. In Tris buffer they become exposed and react in the order 89, 55, 197, 115, 270, 319. This together with the result that in Tris buffer the rat of inactivation caused by trypsin is higher than in phosphate buffer indicates that Tris buffer changes drastically the properties of the enzyme. 6. Cross-linking of the enzyme molecule with bifunctional reagents and subsequent dodecylsulfate-polyacrylamide electrophoresis shows that the six identical polypeptide chains are arranged in two groups of three. 7. The implications of these results for the tertiary and quaternary structure of beef liver glutamate dehydrogenase are discussed.

Animals↗
PubMed1975

Evaluation of craniofacial surgery in the treatment of facial deformities.

Surgical access to the cranial, orbital, and facial areas, as developed by Tessier, has produced not only definitive repair of previously uncorrectable congenital deformities such as orbital hypertelorism and facial stenosis (e.g., Crouzon's, Apert's syndromes) but also has improved markedly the treatment of traumatic and neoplastic defects. The surgical approach allows complete dissection of facial soft tisses including the orbits from the underlying bones followed by corrective osteotomies and fixation. Mobilization of the frontal lobes through a frontal bone flap exposure may be required. The ramifications of this latest intrusion by surgeons into a previously inviolate anatomic area have involved neurosurgeons, ophthalmologists, anesthesiologists, and dental and psycho-social disciplines. The disciplines of genetics and embryology are being influenced by this new field of surgery, much as the study of immunology was influenced by transplantation surgery two decades ago. This report analyzes a 10 year experience with over 100 patients with emphasis on patient selection by disease, age, intellectual status, morbidity, complications, and the psycho-social reactions of patient and family. Procedures initially planned to correct dental and aesthetic defects are proving beneficial for other functions including hearing, taste and smell, articulation and tongue movement, respiratory function, vision, and possibly bone growth. The development of self image, a normal process always in operation, is also strikingly altered. These operations may last as long as 14 to 16 hours. We have had no deaths or postoperative blindness. One postoperative cerebrospinal fluid leak was successfully repaired. Three partial losses of bone grafts and four instances of late cellulitis have occurred. Prevention of infection seems related to avoidance of dead spaces and primary closure of all mucosal, dural, conjunctival and skin surfaces.

Adolescent↗
PubMed1979

Regeneration and myelination in autonomic ganglia transplanted to intact brain surfaces.

Fragments of superior cervical ganglia (SCG) from donor rats between newborn and three months of age were transplanted either into the fourth ventricle, onto the dorsal surface of the medulla or in contact with the area postrema of recipient rats aged 6--14 days (allografts) and 3--4 weeks (autografts). Except for the meninges, the entire brain surface and parenchyma was undisturbed. The regenerative capacity of the transplanted ganglia and its interaction with the brain surfaces was followed for post-operative periods between 1 h and six months. Both ependymal and glial cells reacted to the transplant even though there was no mechanical damage to the brain. Ependymal cells developed luminal fronds that projected into the ventricle and the subpial glia displayed a very subtle gliosis in the form of thin multi-laminated processes. Schwann cells from the transplant tended to cover the free surfaces of the brain. The transplants, often incorporated into the stroma of the choroid plexus, received an extensive vascular supply of both fenestrated and non-fenestrated vessels. In contrast to SCG in tissue culture, the perinatal explants quickly degenerated while all those from older donors, at least 3--4 weeks of age, regenerated briskly in the ambient cerebrospinal fluid. Thriving SCG neurons, which diminished in number over time, sprouted numerous neurites as early as one week; growth cones and synaptic contacts between cell processes were still evident at six months. The trasplanted mature SCG fragment underwent a redevelopment after an initial period of degeneration. It seems likely that the survival of the allografted ganglion cells depends on their acquisition of a target site in their new environment. By four to six months many axons became enclosed by myelin produced by SCG Schwann cells that normally do not form myelin in situ. Other Schwann cells appeared reactive in that they had a great increase in cytoplasmic filaments and formed gap junctions, two characteristics of C.N.S. astrocytes. It is possible that the proximity to the C.N.S. changes the character of certain Schwann cells or, alternatively, resulted in the migration of glial cells out of the brain. If the glial cells have migrated into the transplant, they may support alien neural tissue. This system in which the transplantation site is easily accessible with a minimum of trauma could lend itself to the study of some underlying mechanisms of the growth and regulation of both central and autonomic neurons and their supporting cells.

Animals↗