Calorimetric evidence for phase transitions in spin-label lipid bilayers

Dispersions of pure, spin-label phosphatidylcholines in aqueous buffer have been investigated with the Privalov high-sensitivity differential scanning calorimeter. The lipids studied are mixed-chain ones in which C-2 of glycerol bears a spin-label derivative of stearic acid and the fatty acid group at C-1 is palmitate. A well-defined phase transition is observed at 30.3-30.7 degrees C for the phosphatidylcholine labeled near the polar end of the stearate chain (label at C-5). A sharp transition (32-34 degrees C) is also observed for the lipid spin-labeled near the terminal methyl of stearate (label at C-16), but the thermodynamic parameters for this lipid depend strongly on the history of the sample. Calorimetric evidence for hysteresis in the phase transition of the C-16-labeled lipid is presented. In contrast to the above spin-label lipids, the lipid labeled at C-12 does not show a sharp transition in the region 5-35 degrees C. In general, therefore, the thermal behavior of the spin-label phosphatidylcholines resembles that of phosphatidylcholines bearing double bonds or branched methyl groups at similar locations on acyl chains. During synthesis of mixed-chain lipids, migration of acyl chains occurs. Methyl esterification procedures which are compatible with the acid-labile spin-label group are described. Gas chromatographic analysis of methyl esters shows that chain migration during synthesis gives 15-20% of the spin-label fatty acid at the glycerol C-1 position.

Vascular endothelial cell effectors in fetal calf retina, vitreous, and serum

The vascular endothelial growth factor or factors (VGF) and the cytotoxic component(s) in fetal calf retinal extract, vitreous, and serum were investigated. A new quantitative method of measuring the cell growth stimulatory activity and cytotoxicity was used. Results obtained in this study suggest that the VGF may be present in retina, vitreous, and serum in situ. The VGF was found to be specific for fetal aortic endothelial cells. The VGF was diffusible and could be readily separated by dialysis from the nonspecific cell growth stimulatory factor(s) also present in retinal extract, vitreous, and serum. The VGF activity in the dialyzable fraction was stable at pH 3 and with heat treatment. The VGF appeared to consist of up to three components: VGFI, VGFII, and VGFIII. These components could be separated by cation-exchange chromatography, with an identical elution pattern for each component regardless of tissue origin. Serum and retinal extract contained all three components, whereas in vitreous, VGFIII was either negligible or totally lacking. The cytotoxic component(s) was found only in vitreous and serum, and its cytotoxicity appeared to be nonspecific.

Neurologic, psychiatric, and cardiovascular complications in children struck by lightning

The neurologic changes following lightning injury include coma with cerebral edema, inappropriate secretion of antidiuretic hormone (ADH), seizures, cerebellar ataxia, and painful sensory disturbances. Deteriorating neurologic status may warrant the use of intracranial pressure monitoring devices. Myocardial injury and transient hypertension are generally evident at the onset. Monitoring of the cardiac rhythm may be needed for as long as a week for late onset arrythmia. Abnormalities of memory, mood, and affect noted on recovery of consciousness may persist for months, necessitating close psychiatric and neurlologic follow-up.

Rupture of the extensor pollicis longus tendon in undisplaced Colles' type of fracture

There is a higher risk that the tendon of extensor pollicis longus will rupture in undisplaced Colles' type of fracture than in those which are displaced. This difference in incidence is due to the integrity of the extensor retinaculum in undisplaced Colles' type of fracture causing the tendon to be held tight against the fracture callus in the floor of the tunnel which may result in an attrition rupture. In the displaced Colles' fracture the extensor retinaculum is torn from the bone and thus permits the tendon to escape from contact with the fracture site.

The Orbit-Lattice Interaction for Lanthanide Ions. III. Superposition Model Analysis for Arbitrary Symmetry

Explicit formulae are obtained for the superposition model contributions to phenomenological orbit-lattice parameters for sites of arbitrary symmetry. As an example, these results are applied to derive expressions for the orbit-lattice parameters in C3h and D3h symmetry, without the assumption of uniform strain.

Rheumatic fever in children. A follow-up study with emphasis on cardiac sequelae

Eighty-nine children with rheumatic fever between 1964 and 1978 were reviewed. There were 40 males and 49 females. The first attack occurred mostly between 6 and 12 years. Arthritis was present in 62.9%; carditis, 55.1%; chorea, 19.1%. Children were followed from 20 months to 15 years (mean 61 months). Seventeen developed current attacks (19.1%). On final examination, 40 had no heart disease, 30 had mild heart disease, 6 required valve surgery, 4 had died, and 9 had moderate heart disease but not operated. Chorea was present in 20 children. Six of them also had mitral insufficiency, 3 had recurrence after episode of chorea. Prompt diagnosis and treatment of streptococcal infection and penicillin prophylaxis need to be stressed. Service carditis on initial attack and recurrence predispose to the development of severe heart disease.

Thermotropic behavior of bilayers formed from mixed-chain phosphatidylcholines

The six possible phosphatidylcholines containing two different chains derived from myristic, palmitic, and stearic acids were synthesized, and their bilayer structures were investigated by high-sensitivity differential scanning microcalorimetry. Chain migration during the syntheses caused each of the lipids to contain about 10% of the corresponding positional isomer. A phase diagram for each pair of isomers was constructed to permit estimation of the transition properties of the pure mixed-length phospholipids. The phase transitions of these lipids were found to be similar to those of saturated like-chain phosphatidylcholines. The main transition temperatures and enthalpies fall within the range of those for the like-chain lipids. In each pair of positional isomers, the isomer having the longer chain at position 2 on the glycerol backbone has the higher transition temperature and enthalpy. The transition curves of the pure mixed-chain lipids with myristic acid at position 2 and either palmitic or stearic acid at position 1 exhibited two partially separated peaks for the main transition. No satisfactory interpretation of this unexpected phenomenon has been developed.

De novo partial 2p duplication with postmortem description

An unbalanced karyotype most likely consisting of a partial duplication of the short arm of chromosome 2 (p13 leads to pter) was found in a newborn infant with intrauterine growth retardation, facial, skeletal, and cardiac abnormalities. There was no evidence of a translocation in either parent. At autopsy, striking histopathologic abnormalities were detected in the central nervous system and ovaries.

A radiological study of the movements of the two components of the Monk prosthesis (hard-top 'duo-pleet') in patients

Following replacement of the femoral head with the Monk hard-top 'duo-pleet' prosthesis, radiological studies show that movement of the replaced hip takes place between the acetabulum and the metal shell and between the high density polyethylene cup and metal ball. Movements improve with the passage of time. The two sites of movement may contribute to a greater range of hip movement, a better safeguard against loosening and possibly less medial migration of the prosthesis than solid metal prostheses like the Thompson and Austin Moore types.

Scanning calorimetric evidence for a third phase transition in phosphatidylcholine bilayers

A third phase transition, centered at about 18 degrees C, was observed by differential scanning calorimetry in a multilamellar suspension of dipalmitoyl phosphatidylcholine that had been held at 0 degrees C for several days. This transition is less cooperative than the other two transitions which are well known for this system, and it is accompanied by an enthalpy increase about three times as large as that of the so-called pretransition at 35 degrees C and about half that of the main gel to liquid crystal transition at 41 degrees C. The reversal of this transition on cooling is extremely slow.

Preliminary results of the Sheehan total knee prosthesis

A review of 50 knees in 42 patients operated upon between August, 1973 and November, 1976 is presented. Following initial good results, problems have been encountered with the passage of time. Complications due to design faults, selection, and technical pitfalls are analysed. Patients who have grossly unstable and deformed knees are not suitable for this type of prosthesis. The high density polyethylene central flange in the tibial component is not strong enough to withstand valgus or varus forces. Full correction of valgus, varus, or flexion deformities is essential if late complications are to be avoided. Associated external rotation deformities in grossly valgus knees have to be fully corrected to prevent late dislocation of the patella. Our conclusion is that at present there is a place for both the hinged and hingeless type of prosthesis in total knee replacement.

Response of rats fed diets low in glucose and glucose precursors to low levels of glucose, starch and chemically modified starch

Several levels of glucose or starches were added to a basal diet that was free of available carbohydrate and low in carbohydrate precursors and fed to male, weanling rats. Rats fed such diets were highly responsive to dietary carbohydrate in growth rate, blood glucose levels and blood ketone bodies. There were no significant differences in the activities of pancreatic amylase, liver glucokinase, glucose-6-phosphatase and fructose-1,6-diphosphatase when dietary carbohydrate varied from 1.5 to 6% of the diet. Under these feeding conditions, a minimum of 6% by weight or 5.8% of the dietary calories has to be provided by carbohydrate to allow the rat an optimum rate of growth. Such diets that are low in glucose precursors were employed as an assay system for glucose availability from chemically cross-bonded starches with various degrees of phosphate crosslinkage. The data showed that introducing low levels of phosphate crosslinkages into the starch had little effect on the glucose availability from the starch.

A clinicopathologic study of choledochal cyst

Choledochal cyst is quite common in Japan. The etiology of this lesion is not clear, and there remain problems in its treatment as well. Radiologic investigation of the distal common bile and pancreatic ducts was performed by operative cholangiography and endoscopic retrograde cholangiopancreatography. Anomalies at the junction of these ducts were found in all of the patients. Localilzed cystic dilatation of the extra-hepatic bile ducts without intrahepatic bile duct dilatation was produced experimentally by ligation of the distal choledochus in infant rats. Concerning the etiology, we agree with Babbitt's hypothesis that weakness of the choledochal wall is produced by reflux of pancreatic juice via an anomalous choledochopancreatic junction. We think that the stenosis associated with this anomaly is the critical factor. From our follow-up study of 30 cases, we find excision of the cyst to be the most important part of treatment. Choledochal cysts presenting under 6 months of age had clinical symptoms and pathology similar to biliary atresia.

Post-milking iodine teat skin disinfectants. 3. Residues

Teat dipping of lactating cows with either 1000 or 5000 mg available iodine/; (mg avI/;) solution and thoroughly washing and drying of the teats before sampling resulted in levels of 70 and 99 micrograms avI per quarter per milking respectively. Without any pre-milking udder preparation prior to sampling the levels of iodine recorded were 143 and 291 micrograms avI per quarter per milking respectively. Some systemic transfer of iodine from the teat skin to the milk was observed, but the bulk of iodine residue in milk was of direct teat skin origin.

Methylmalonic acid metabolism of germfree and conventional vitamin B-12 deprived rats fed precursors of methylmalonate

Experiments using germfree (GF), ex-germfree (XGF) and conventional (CONV) rats were conducted to study the relationship of intestinal microorganisms to vitamin B-12 (B-12) status and to methylmalonic acid (MMA) excretion of the host animal, since B-12 depleted GF rats have been found to excrete less than expected level of urinary MMA. The possibility that the GF rat lacks sufficient precursor of MMA was tested by feeding GF, XGF and CONY rats diets low or high in MMA precursors and examining urinary excretion of MMA and formiminoglutamic acid at intervals. The possibility that the GF rat may metabolize propionate and MMA differently from the CONV rat was examined by a MMA loading-recovery study and a CO2 collection study after [14C]propionate injection. Plasma and tissue B-12 levels were determined at the beginning and the end of the study. Results indicate that 1) lack of sufficient precursor of MMA is partly responsible for the failure of GF, B-12 deficient rat to excrete MMA, 2) GF and CONV rats metabolize propionate and MMA by the same pathways and 3) the presence of intestinal microorganism depletes the body B-12 store of the rat.

Extraction procedures for use prior to HPLC nucleotide analysis using microparticle chemically bonded packings

In preparing nucleotide extracts for HPLC analysis using microparticle, chemically bonded packings, tri-octyl-amine-freon solutions can be used for the extraction of the acid from the solution if the concentration of the amine is carefully controlled.

Long-term results of stapling of the knee

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Infantile coxa vara with superimposed Perthes-like change

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