PubMed Health⌕ Search

Biomedical subjects

K A Rich

Publications and source records attributed to K A Rich.

7 recordsLinked to original sources
PubMed1990

Cell-adhesive motif in region II of malarial circumsporozoite protein.

The segment of the malarial circumsporozoite (CS) protein designated Region II is highly conserved among different malarial species. A similar sequence is also present in several other proteins, including thrombospondin, properdin, and a blood-stage antigen of Plasmodium falciparum. By means of peptides synthesized from sequences of the Plasmodium vivax CS protein in the vicinity of Region II, it was found that two overlapping 18- to 20-amino acid peptides promoted the adhesion of a variety of human hematopoietic cell lines. The amino acid sequence valine-threonine-cysteineglycine (VTCG), contained within this common motif, was shown to be the critical sequence for the observed cell-adhesive properties.

Amino Acid Sequence↗
PubMed1990

Identification of a T-cell epitope on the circumsporozoite protein of Plasmodium vivax.

A series of overlapping peptides, representing sequences in the vicinity of region II on the Plasmodium vivax circumsporozoite protein, was synthesized. One of the peptides (PV-23), a 20-mer containing the 6 C-terminal amino acids of region II, was found to evoke an in vitro T-cell proliferative response in spleen cells from C3Hf (H-2km2) mice immunized with the peptide. These results demonstrate that PV-23 contains a T-cell epitope. To our knowledge, this is the first report of a T-cell epitope on the circumsporozoite protein of P. vivax.

Amino Acid Sequence↗
PubMed1979

Evidence for Leydig cell dysfunction in rats with seminiferous tubule damage.

To study the effects of seminiferous tubule damage on Leydig cell function and morphology, rats were treated by fetal irradiation (to induce Sertoli cell-only syndrome, SCO), 3 months administration of hydroxyurea (HU), or chronic feeding of a vitamin A-deficient diet (VAD). Leydig cell function was assessed by the measurement of serum LH and testosterone and the response of serum testosterone to hCG stimulation, while morphology was studied by electron microscopy after perfusion fixation. Serum LH was significantly elevated in each experimental group, while basal serum testosterone was significantly lower only in SCO rats. In all treatment groups, the serum testosterone response to hCG was significantly decreased when measureed as the area under the response curve. Despite a decreased response to hCG, the Leydig cells were larger than normal and showed striking increases in quantities of smooth endoplasmic reticulum, mitochondria and Golgi complex. Leydig cell dysfunction has been demonstrated in animals with varying degrees of seminiferous tubule damage, but paradoxically the cytological features of the Leydig cells were indicative of hypertrophy.

Animals↗
PubMedDate not supplied

Carrageenin-induced arthritis. III. Proteolytic enzymes present in rabbit knee joints after a single intraarticular injection of carrageenin.

A single intraarticular injection of carrageenin into the rabbit knee joint initiates an inflammatory reaction in the synovial tissues. the exudate from the joint was able to degrade proteoglycan at pH 5.2 and pH 7.2. Further characterization of proteolytic enzymes in the inflamed synovial tissues showed the presence of cathepsin D, a neutral protease, and cathepsin B1. Maximum activities of two lysosomal enzymes, acid phosphatase and cathepsin D, were observed within 7 days of injection. Most of this activity was found to be associated with cells in the synovial fluid.

Acid Phosphatase↗