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Biomedical subjects

S Morris

Publications and source records attributed to S Morris.

At least 235 records · Page 13Linked to original sources
PubMed1983

Chicken lens delta-crystallin gene expression and methylation in several non-lens tissues.

RNA sequences coding for the most abundant chicken lens proteins, delta-crystallin, were detected at very low levels in day old post hatch chick lung, heart, kidney and liver, and in 6 day embryo headless bodies. The pattern of cytosine methylation within the CCGG sequences of the delta-crystallin genes was also examined and shown to vary in several non-lens tissues, from several stages of development. Embryonic neural retina, which expresses a higher level of delta-crystallin RNA than the above tissues, is no less methylated in the sites studied than the tissues which have no association with the eye, and is actually more heavily methylated than the kidney. Thus no obvious correlation was found between undermethylation and gene expression.

Animals↗
PubMed1983

Human cytomegalovirus-specific cytotoxic T lymphocytes: requirements for in vitro generation and specificity.

The nature of any virus-specific T cells involved in controlling human cytomegalovirus (HCMV) infection in normal subjects harboring latent virus is unknown. As an approach to this problem, peripheral blood mononuclear cells (PBM) from normal seropositive subjects were cocultured with HCMV and responding T cells expanded in interleukin 2 (IL2)-dependent culture, determining in particular whether HCMV-specific cytotoxic T cells (Tc) were generated. Coculture of PBM with free HCMV resulted in the generation of short-term T cell lines of predominantly helper phenotype (Leu 3a+), expressing no cytotoxicity. However, when PBM were cocultured on HCMV-infected fibroblasts (autologous to the donor in these experiments) predominantly Leu 2a+ lines were generated, which lysed HCMV-infected cells. The cytotoxicity of these short-term IL 2-dependent lines was HCMV-specific and human HLA-restricted; HCMV-infected target cells expressing only early viral antigens were lysed. It is concluded that HCMV-specific Tc precursors are present in peripheral blood of latently infected individuals without preceding overt infection and that effector Tc may be capable of lysing infected cells prior to viral replication.

Antigens, Viral↗
PubMed1983

The pattern of expression of chick delta-crystallin genes in lens differentiation and in trans-differentiating cultured tissues.

During development of the vertebrate lens, the lens epithelium undergoes a final stage of differentiation into lens fibre cells. Lens fibre cells can also be produced by trans-differentiation from certain extralenticular structures, all of which are of different developmental origin from lens, including embryonic neural retina and retinal pigmented epithelium. Delta-crystallin is the major lens protein in the chick and appears first in development; it is the major product in trans-differentiated retina of younger embryos. In both normal differentiation and trans-differentiation an increase of delta-crystallin coding RNA is detectable in the nucleus of cells prior to their terminal differentiation into lens fibres. The increase in transcription of delta-crystallin genes accompanying final differentiation of lens fibres, appears to take place slightly in advance of an increase in the capacity to process and transport this mRNA to the cytoplasm.

Animals↗
PubMed1982

Cytoplasmic RNA sequences complementary to cloned chick delta-crystallin cDNA show size heterogeneity.

Double-stranded complementary DNA (cDNA) sequences were prepared from day-old chick lens total polysomal RNA and inserted into the unique PstI restriction site of the plasmid pBR322. Colonies containing sequences complementary to abundant lens poly(A)-containing RNA sequences were identified by using lens 32P-labelled cDNA. Some of these clones have been characterized as containing delta-crystallin mRNA coding sequences by genomic DNA blot hybridization and RNA blot hybridizations. Hybridization of labelled DNA from such clones to RNA blots detected four size classes of delta-crystallin RNA sequences, although Southern blots indicated that there are probably only two delta-crystallin genes.

Animals↗
PubMed1982

Development of sexual dimorphism in the suprachiasmatic nucleus of the rat.

Synapses develop at similar rates in the suprachiasmatic nucleus of rats of both sexes, but values are higher in male than in female animals from birth to maturity. Male-type development cannot be mimicked by neonatal androgenization but results suggest that female-type development can be induced by neonatal castration of males. The results suggested that both prenatal and postnatal androgens are essential to normal male development.

Animals↗
PubMed1980

Clinical experience with sodium valproate in children.

Good control was achieved with sodium valproate (Epilim) in 44 (71%) of a sample of 62 children with severe recurrent epileptic seizures. The medication was most effective in the control of petit mal; good results, however, were also achieved in some patients with previously poorly controlled grand mal epilepsy and psychomotor and myoclonic seizures. Twenty children required no other anti-convulsant and 28 required only one other. Side-effects were infrequent and mild. Only the high cost of sodium valproate in South Africa precludes its more general use in childhood epilepsy.

Adolescent↗
PubMed1980

Complement deficiency and nephritis. A report of a family.

A family is described in which three children had homozygous deficiency of C3 and in which both parents and two other children were heterozygous for the C3 null gene. One child with heterozygous C3 deficiency was found to have membranoproliferative glomerulonephritis; proteinuria and/or microscopical haematuria was present in all three homozygous C3-deficient children. All children with homozygous or heterozygous C3 deficiency were, to a varying degree, susceptible to infection. The only child of the family with normal complement had no increased risk of infection and no renal disease. This family study provides further support for the proposal that C3 deficiency predisposes to nephritis.

Adolescent↗
PubMed1980

Origin of glycerylphosphorylcholine, inositol, N-acetylaminosugar, and prostaglandins in human seminal plasma and their effects on sperm metabolism.

The origin of glycerylphosphorylcholine (GPC), N-acetylaminosugar, inositol, and prostaglandins in human seminal plasma was investigated by correlating the concentration of these components in split ejaculates with known marker constituents. Fructose and acid phosphatase were selected as markers of the secretory activity of the seminal vesicles and prostate gland, respectively, and spermatozoa indicated epididymal origin. The concentration of fructose was lowest in the first fraction of the semen and increased to a maximum in the final portion. Prostaglandins E and F and N-acetylaminosugar values closely followed this pattern, indicating that these components originate in the seminal vesicles. The concentration of spermatozoa was high in the first two fractions, decreasing to a minimum in the final fraction. The distribution of GPC was similar to that of the spermatozoa, indicating that the epididymis secretes this compound. Inositol levels were similar in all fractions, indicating that it is probably present in epididymal, vesicular, and prostatic fluid. Human spermatozoa were unable to utilize N-acetylglucosamine or inositol. High concentrations of some prostaglandins (100 micrograms/ml of PGF1 alpha, 15S 15 met. F2 alpha, PGA1, and PGA2) depressed the endogenous oxygen uptake of human spermatozoa.

Acetylglucosamine↗
PubMed1978

Kinetic studies on the activation of human factor X. The role of metal ions on the reaction catalyzed by the venom coagulant protein of Viper russelli.

The effect of Ca2+, Mg2+, and Mn2+ on the initial rate of activation of human Factor X by the venom coagulant protein of Vipera russelli has been investigated. Neither Mg2+ nor Mn2+ alone support the reaction. Ca2+ is an essential activator and exhibits cooperative kinetics. Both Mg2+ and Mn2+ enhance the reaction cooperatively when Ca2+ is present at suboptimal concentrations. Similarly, Ca2+ quenches the intrinsic fluorescence of human Factor X in a cooperative manner. While neither Mg2+ nor Mn2+ by themselves affect the fluorescence of human Factor X, they decrease the cooperativity of the Ca2+ binding to the protein as judged by Hill plots of the Ca2+ -induced fluoresence quenching. EPR measurements indicate that there are three high affinity Mn2+ binding sites on human Factor X which can also bind Ca2+. Positive cooperativity was not observed for Mn2+ binding. These data indicate that Ca2+ can cause a conformational change of the Factor X molecule which allows the activation reaction to proceed. We propose that Mn2+ does not support the activation of human Factor X because it cannot induce a necessary conformational change in the absence of Ca2+.

Calcium↗