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Biomedical subjects

F John

Publications and source records attributed to F John.

At least 19 recordsLinked to original sources
PubMed1998

Betaine-homocysteine methyltransferase is a developmentally regulated enzyme crystallin in rhesus monkey lens.

We describe herein the characterization of a major 45-kDa protein from the soluble betaH-crystallin fraction of rhesus monkey (Macaca mulatta) lens. Based on partial peptide sequence, immunoreactivity, and enzymatic activity, this protein has been identified as betaine-homocysteine S-methyltransferase (BHMT: EC 2.1.1.5), an enzyme that catalyzes the methylation of homocysteine using either betaine or thetins as methyl donors. This protein was found to be expressed abundantly in the nuclear region of the monkey lens, reaching approximately 10% of the total nuclear protein, but was barely detectable in the epithelium and cortex regions of the lens. Because the nucleus represents the early embryonic and fetal stages of lens development, we infer that BHMT expression in the lens of the eye is developmentally regulated. By virtue of its high abundance, BHMT can be considered an enzyme crystallin (psi-crystallin). This is the first enzyme crystallin to be found in primate lenses.

Adolescent↗
PubMed1988

Existence for large times of finite amplitude elastic waves arising from small disturbances.

This paper deals with strict solutions u(i)(t, x(1), x(2), x(3)) of a system of quasi-linear equations [Formula: see text] with u' = ([unk](x(i) )u(k)), and i, k, r, s ranging over 1, 2, 3. For given initial conditions u(i) = epsilonf(i)(x(1), x(2), x(3)), [unk](t)u(i) = epsilong(x(1), x(2), x(3)) for t = 0 the life-span T(epsilon) is the supremum of all t > 0 to which the u(i) can be extended as strict solutions for all x. It is shown that lim inf(epsilon-->0) epsilon log T(epsilon) > 0 for C(ikrs), f(i), g(i) [unk] C(0) (infinity), and C(ikrs) = C(rsik), C(ikrs)(0) = 0.

Journal Article↗
PubMed1987

[Modification of fracture healing by ultrasonics in an animal model. 2. Radiologic and histologic results].

Both tibiae were osteotomised and medullary nailing in 40 rabbits. In each case the right fracture was treated with ultrasound of 0.1 W/cm2 for 2 minutes every second day altogether 4 times. The left extremity was used as control. The estimation of the mineralization took place semiquantitatively after weekly radiologic checks, this one of the callus maturation histologically in the decalcified bone. By ultrasound treatment an enlarged callus formation and an accelerated callus maturation was shown in contrast to the untreated extremity. An accelerated three-phasic fracture healing was provable by ultrasound influence. The advantage of the mineralization amounted to 2 weeks in the 4th postoperative week. The ultrasound influence of the fracture healing shows, therefore, as remedy of choice in comparison with other stimulation methods.

Animals↗
PubMed1984

[Modification of bone fracture healing by ultrasound in an animal experiment model].

Both tibiae were osteotomised after medullary nailing in 40 rabbits. In each case the right fracture was treated with ultrasound of 0.1 W/cm2 for 2 minutes 4 times every second day after on week. The left extremity is used as control. An accelerated and increased callus formation and callus maturation were found by ultrasonic therapy. This was possible to be shown on a higher level of the alkaline phosphatase, a higher temperature, and an accelerated calcium and phosphate incorporation in the callus in comparison with the untreated side. The mineralisation by means of ultrasound showed a characteristical three phase behaviour. The mechanism of action is probably the piezo-electric effect of the local tension induction by ultrasound with resultant activation of the metabolism. The advantage of the mineralisation amounted to 2 weeks in contrast to the untreated extremity in the 4th week after the fracture. These findings confirm numerous positive clinical results.

Alkaline Phosphatase↗
PubMed1982

Lower bounds for the life-span of solutions of nonlinear wave equations in three dimensions.

The paper deals with strict solutions u(x,t) = u(x(1),x(2),x(3),t) of an equation [Formula: see text] where Du is the set of four first derivatives of u. For given initial values u(x,0) = epsilonF(x), u(t)(x,0) = epsilonG(x), the life span T(epsilon) is defined as the supremum of all t to which the local solution can be extended for all x. Blowup in finite time corresponds to T(epsilon) < infinity. Examples show that this can occur for arbitrarily small epsilon. On the other hand, T(epsilon) must at least be very large for small epsilon. By assuming that a(ik),F,G [unk] C(infinity), that a(ik)(0) = 0, and that F,G have compact support, it is shown that [Formula: see text] for every N. This result had been established previously only for N < 4.

Journal Article↗
PubMed1981

[Elimination of pain by percutaneous thermorhizolysis in patients with inoperable bronchial carcinoma (author's transl)].

The percutaneous thermorhizolysis is a relatively simple technique for interrupting root function in the paravertebral space. Pain-conducting fibers can be selectively inactivated by a thermal probe heated to controlled temperatures. In a series of 25 cases with terminal cancer pain syndrome a good to very good relief of pain was obtained in 18 cases. In 4 cases the pain relief was partial. Only in 3 cases the treatment was completely ineffective. The procedure can be applied to patients who are debilitated due to carcinoma or old age and can be repeated if necessary.

Adult↗
PubMed1980

Nonexistence of global solutions of squareu = F(u) and of squarev = F'(v)v in three space dimensions.

The symbol square denotes the operator partial differential(2)/ partial differential(2) - Delta in three space dimensions, and F denotes a function with F(0) = F'(0) = 0, inf F'' > 0. It is shown that u(x,t) identical with 0, if squareu = F(u(tt)) for xin R(3), t >/= 0, provided u,u(t),u(tt) for t = 0 have compact support. Similarly v(x,t) identical with 0 if squarev = F'(v(t))v(tt) for x in R(3), t >/=0, provided v,v(t) for t = 0 have compact support and satisfy integral[v(t) - F(v(t))]dx >/= 0. This shows that the global existence theorem proved by S. L. Klainerman [(1980) Commun. Pure Appl. Math. 33, in press] in more than five space dimensions is not valid for three dimensions. The theorems also imply instability at rest of certain hyperelastic materials.

Journal Article↗
PubMed1979

Epidemic hepatitis B caused by commercial human immunoglobulin.

An epidemic of acute hepatitis B followed the administration of human immunoglobulin to members of the staff of a mission hospital in India and their families. Jaundice developed in 123 (38%) of 325 persons inoculated. Hepatitis-B surface antigen was detected in three of the batches of immunoglobulin which were available for testing.

Counterimmunoelectrophoresis↗
PubMed1979

Distribution and metabolic fate of adenosine nucleotides in the membrane of storage vesicles from bovine adrenal medulla.

The reactions of adenosine 14C-and gamma 32P-labelled ATP with isolated membranes from catecholamine storage vesicles of the bovine adrenal medulla were studied. In presence of Mg2+ about twice as much of 32P-radioactivity combined with the membrane as 14C-adenosine compounds at 31 degrees C and also at 0 degrees C, while in the absence of Mg2+ the amounts of 14C and 32P incorporated were similar for both substances. Autoradiography of the SDS-polyacrylamide gel after electrophoresis of the 32P-ATP-treated membrane protein showed two distinct zones corresponding to protein bands. Sonication released twice as much 32P-ATP as 14C-ATP from the space within the membrane particles indicating that at least half of the ATP present in space did not contain its original terminal phosphate group. About 40--45% of the 32P-radioactivity was incorporated in the membrane lipids, whereas only small amounts of 14C-radioactivity were extracted with lipids. About 1/3 of the incorporated 14C-radioactivity was not extractable with acids. The same amount remained in the 32P-ATP treated preparation acid-stably bound after extraction of the lipids and hus must be firmly bound ATP. When the reaction of the membrane preparation with labelled ATP was performed at 0 degrees C the fractions of the acid-stably bound 32P- and 14C-radioactivity increased. About 1 nmole/mg of protein (10--15%) of the bound 32P-radioactivity was exchangeable against unlabelled ATP, while only a very small fraction (less than 0.5 nmol/mg protein) of the 14C-radioactivity was exchanged against unlabelled ATP. Preincubation of the membrane particles with ATP-Mg2+ at 0 degrees C induced 30% inhibition of the ATPase activity and abolition of the net uptake of catecholamines. Different Km values obtained from initial velocity studies of ATPase activity and the overall-incorporation of 32P-radioactivity indicated that a direct correlation between these processes did not exist. Different strong inhibitory effects exerted by ADP on the ATPase activity and net uptake of catecholamine at the one hand and the overall 32P-and 14C-incorporation at the other hand supported that view. It is concluded that small fractions of the observed 32P-and 14C-incorporation can be involved in the ATP hydrolyzing reaction.

Adenine Nucleotides↗
PubMed1979

Blow-up of solutions of nonlinear wave equations in three space dimensions.

Solutions u(x, t) of the inequality squareu >/= A|u|(p) for x epsilon R(3), t >/= 0 are considered, where square is the d'Alembertian, and A,p are constants with A > 0, 1 < p < 1 + radical2. It is shown that the support of u is compact and contained in the cone 0 </= t </= t(0) -|x - x(0)|, if the "initial data" u(x, 0), u(t)(x, 0) have their support in the ball|x - x(0)| </= t(0). In particular, "global" solutions of squareu = A|u|(p) with initial data of compact support vanish identically. On the other hand, for A > 0, p > 1 + radical2, global solutions of squareu = A|u|(p) exist, if the initial data are of compact support and "sufficiently" small.

Journal Article↗
PubMed1977

Restrictions on the coefficients of hyperbolic systems of partial differential equations.

THE PAPER DEALS WITH HYPERBOLIC HOMOGENEOUS SYSTEMS [FORMULA: see text] of partial differential equations with constant coefficients for an N-vector u(t,x(1),...,x(n)). Here, P is a matrix form of order N and degree m. In the scalar case (N = 1), every hyperbolic P is limit of strictly hyperbolic ones. This does not hold for systems as is shown here for the special case N = n = 3, m = 2. Assuming P(1,0,...,0) to be the unit matrix, we represent P by a point in R(81). The hyperbolic P form a closed set H in R(81), the strictly hyperbolic ones an open subset H(s) of H. An example is given for a P in H which is not in the closure of H(s). Moreover, it is shown that near that P the set H coincides with an algebraic manifold of codimension 4.

Journal Article↗
PubMed1977

Immune complex glomerulonephritis associated with Klebsiella pneumoniae infection.

The kidneys of three patients who died of pneumonia due to Klebsiella pneumoniae were studied at autopsy by light and immunofluoerescent microscopy. One had no clinical evidence of renal disease; two had only microscopic hematuria and mild proteinuria. Light microscopy revealed focal proliferative glomerulonephritis in all three cases. Also in all three, immunofluorescent microscopy revealed a granular deposition of capsular polysaccharide antigens of Klebsiella pneumoniae in association with immunoglobulins and complement components in the mesangium and along the glomerular basement membrane. Furthermore, the glomerular bound immunoglobulins were eluted and demonstrated to contain antibodies specific to a capsular polysaccharide antigen of Klebsiella pneumoniae isolated from each patient. These findings may illustrate that the capsular polysaccharides of Klebsiella pneumoniae are antigenic, and that the immune complex deposition in the kidney during infection with this agent can be associated with renal morphological changes. Whether or not clinical evidence of nephritis occurs may depend on the characteristics of the infection and the host factors.

Aged↗
PubMed1976

Delayed singularity formation for solutions of nonlinear partial differential equations in higher dimensions.

Strict solutions u of genuinely nonlinear homogeneous hyperbolic equations in two independent variables with initial data f(x) of compact support become singular after a time interval of order parallelf parallel(-1). In higher dimensions solutions initially of compact support are likely to have life expectancies of orders parallelf parallel(-2+epsilon) at least. This is proved for the special case of solutions u(x(1),..., x(n), t) of a second order equation u(tt) = Sigma(i,j)a(ij)u(xixj), where n >/= 3 and where the coefficients a(ij) are C(infinity)-functions in the first derivatives of u, forming a symmetric positive definite matrix.

Journal Article↗
PubMed1976

[Pendular and rotatory vestibular habituation].

The present investigations demonstrate in animals (rabbits) the existence of a habituation to the vestibular pendular stimulation comparable to the rotatory habituation by constant angular acceleration. There is no mutual transfer, however, between the two habituations. This confirms that the two modes of stimulation are not equivalent. All the tests have been made by ENG recording in total darkness.

Animals↗