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Biomedical subjects

J H Davis

Publications and source records attributed to J H Davis.

At least 145 records · Page 8Linked to original sources
PubMed1980

The investigation of electrical deaths: a report of 220 fatalities.

We present the results of our investigation of 220 electrocutions. The ratio of high voltage to low voltage electrocution is found to be nearly 1:1. Further, in low voltage electrocution deaths electrical burns were absent in over 40% of the cases. Our approach to the investigation of possible electrocution, including equipment analysis, is discussed.

Accidents↗
PubMed1979

Study of the cytoplasmic and outer membranes of Escherichia coli by deuterium magnetic resonance.

The cytoplasmic and outer membranes of Escherichia coli were studied between 0 and 40 degrees C by deuterium magnetic resonance quadrupolar echo spectroscopy. The L51 strain of E. coli was used to incorporate perdeuterated palmitic acid into the membrane phospholipids. The cytoplasmic and outer membranes were separated using standard techniques. The spectrum of each membrane preparation was dominated at high temperatures (greater than or equal to 37 degrees C) by the characteristic liquid-crystalline plateau previously observed for perdeuterated palmitate chains in model phospholipid membranes. At low temperatures, the shape and width of the spectrum were characteristic of the gel phase. The relative intensities of the liquid-crystalline and gel features varied systematically with temperature. A quantitative analysis of the acyl chain orientational order was carried out by using the method of moments. The orientational order at each temperature was greater in the outer membrane sample than in that of the cytoplasmic membrane, indicating that the liquid-crystalline-gel transition region in the outer membrane is shifted to higher temperatures than that of the cytoplasmic membrane by about 7 degrees C. It is clear from the results that most of the phospholipid molecules participate in the phase transition.

Cell Membrane↗
PubMed1979

Bilayer rigidity of the erythrocyte membrane2H-NMR of a perdeuterated palmitic acid probe.

Perdeuterated palmitic acid was intercalated into the human erythrocyte membrane and its motion studied by dueterium nuclear magnetic resonance (2H-NMR). From analysis of temperature dependent changes in the 2H-NMR spectra and from an analysis of derived moments we conclude that the acyl chains of the erythrocyte lipids do not exhibit a detectable phase transition.

Deuterium↗
PubMed1979

Pancreatic duct arteriovenous fistula and the metastatic fat necrosis syndrome.

This report summarizes the course of a patient with asymptomatic chronic pancreatitis associated with hemorrhage into the pancreatic duct and metastatic fat necrosis. Retrograde cannulation of the pancreatic duct and superior mesenteric arteriography established the presence of a pseudocyst with a pancreatic duct-arteriovenous (DAV) fistula as the cause of the syndrome. Ligation of feeder vessels with external drainage of the cyst as the initial surgical procedure stopped the bleeding but failed to prevent recurrence of the pancreatic duct-venous fistula. A pancreaticoduodenectomy with resection of the cyst and fistula was required to arrest destruction of distant tissues. Although serum and urine amylase concentrations were markedly elevated, serum lipase levels were normal throughout the patient's course. Elevation of serum lipase does not seem to be a necessary condition for the development of the metastatic fat necrosis syndrome.

Adult↗
PubMed1979

Deuterium magnetic resonance study of the gel and liquid crystalline phases of dipalmitoyl phosphatidylcholine.

Deuterium magnetic resonance is applied to the study of the liquid crystalline and gel phases, and of the phase transition, of a multilamellar dispersion of chain perdeuterated (d62)-dipalmitoyl phosphatidylcholine/H2O. Analysis of the deuterium spectra in terms of the moments of the spectra allows one to make quantitative statements concerning the distribution of quadrupolar splittings even in complicated situations, e.g., when using perdeuterated sampled or when there are mixed phases. This analysis indicates that d62-dipalmitoyl phosphatidylcholine in excess H2O undergoes a sharp phase transition (with a width of less than 1 degree C) at approximately 37 degrees C and that there appears to be hysteresis in the phase transition of approximately 1 degree C. In the lamellar liquid crystalline phase above 37 degrees C the spectra show a number of well-resolved features whose quadrupolar splittings can be followed as the temperature is varied. The gel phase near 20 degrees C possesses a very broad, almost featureless spectrum that does not seem to support a model of the gel phase wherein the hydrocarbon chains are fully extended in the all-trans conformation. At temperatures near 0 degrees C the spectra clearly indicate that a large fraction of the lipid molecules cease the rotation about their long axes, giving a spectrum more characteristic of a rigid or solid sample. These results give a picture of the gel phase as a phase characterized by considerable hydrocarbon chain disorder near 20 degrees C and becoming a more solid-like phase near 0 degrees C. The spin-lattice relaxation time, T1, has been measured at 20 degrees C in the gel phase, and at 37 and 45 degrees C in the liquid crystalline phase. The values of T1 obtained for each of the resolvable peaks in the spectrum at 37 degrees C are compared to the values (for each peak) of T2e, the decay time of the quadrupolar echo, obtained at the same temperature. These results are discussed in terms of a simple two-motion model.

Crystallization↗
PubMed1977

Measles immunization. Successes and failures.

As a result of a large outbreak of measles, measles hemagglutination inhibition (HI) titers were measured in 465 immunized children. Titers of less than 1:4 were found in 14.6% of children immunized at 12 months of age as compared to 5.2% of those immunized at 13 months of age or later. Measles antibody titers were higher in the mothers of seronegative children who had been immunized at 11 or 12 months of age than in the mothers of seroposotive children. Measles HI titers of 1:4 or more were present in 94% of children immunized at 13 months of age or later between 1962 and 1964. The findings suggest that vaccine failure and not waning antibody accounts for the majority of titers of less than 1:4 in immunized children. Reimmunization programs should be considered for those who were immunized before 13 months of age.

Adolescent↗