Partial characterization of a cell-directed inhibitor of leukotaxis in human serum

A leukotactic defect is described in a man with a low cerebrospinal fluid leukocyte count in the presence of an acute listeria meningitis. On the basis of subsequent studies with his serum and normal human serum, a leukotactic inhibitor has been identified. This inhibitor, termed the cell-directed inhibitor (CDI), is relatively heat stable and nondialyzable. By ultracentrifugal analysis in sucrose density gradient, the inhibitor has been resolved into two activities with estimated sedimentation coefficients of 7 and 10 S. It interacts directly with neutrophils and monocytes to render them chemotactically defective. CDI also impairs the phagocytic function of neutrophils. Evidence is presented that an antagonist to the inhibitor is present in normal serum. CDI and its antagonist are probably normally occurring regulators of leukotaxis. In the patient studied, an elevated CDI serum level may be related to the development of the listeria infection and failure of cutaneous response to skin test antigens.     

Acute renal failure secondary to acute pyelonephritis

A six year-old girl presented with acute oliguric renal failure, secondary to acute, non-obstructive pyelonephritis. Evidence for pyelonephritis as the cause of renal failure included: the evolution of typical changes on serial intravenous pyelograms, an acute interstitial inflammatory exudate on percutaneous renal biopsy, and gram-positive cocci on gram stain of the biopsy tissue. Although a specific causative organism was not conclusively identified, enterococcus was isolated from the initial catheterized urine specimen. The patient recovered from the acute illness but was left with impaired renal function, hypertension, and cortical scarring. Acute, non-obstructive pyelonephritis can produce acute renal failure in children and must be considered in the differential diagnosis of this syndrome.     

Forced Convection Heat Transfer to Power-Law Non-Newtonian Fluids Inside Triangular Ducts

A hybrid analytical-numerical approach based on the Generalized Integral Transform Technique is employed to simulate the laminar forced convection (hydrodynamically fully developed and thermally developing laminar flow) of power-law non-Newtonian fluids inside ducts with arbitrary shaped cross-sections. The analysis is illustrated through consideration of both right angularly and isosceles triangular ducts subjected to constant wall temperature as thermal boundary condition. Reference results for quantities of practical interest such as dimensionless average temperature and Nusselt numbers within the thermal entry region were produced for different values of power-law index and apex angles. Finally, critical comparisons are performed with results available in the literature for direct numerical and approximate approaches.     

Recent advances in the pharmacology of the vestibulo-ocular reflex system

Recent advances in the pharmacology of the vestibulo-ocular reflex have had a major impact on our understanding of the vestibular system, the sensory system primarily concerned with the stabilization of gaze and posture during head movement. Increasing evidence suggests that afferent transmission from the receptor hair cells in the vestibular labyrinth to the vestibular nerve probably involves glutamate acting on a number of excitatory amino acid receptor subtypes. Furthermore, hair-cell sensitivity appears to be regulated by cholinergic, GABA-mediated and, possibly, peptide-mediated efferent feedback from the CNS. Likewise, it seems clear that an excitatory amino acid, probably glutamate, is the major transmitter used by the vestibular nerve in its synapses with neurones of the brainstem vestibular nucleus. In this review, Paul Smith and Cynthia Darlington discuss the large number of receptor subtypes that have been identified in the vestibular nucleus, including receptors for several peptides that may have a role in co-transmission.     

Complementary replication R- and G-band patterns induced by cell blocking at the R-band/G-band transition, a possible regulatory checkpoint within the S phase of the cell cycle

The characteristic band patterns of replication banding (dynamic banding) were analyzed. High-resolution (550-1,250 bands per haploid genome) G- and R-band patterns were obtained after 5-bromo-2'-deoxyuridine (BrdU) incorporation during early or late S phase. Thymidine-BrdU permutation culture methods, which arrest DNA synthesis at the R-band/G-band transition, allow complementary BrdU substitution. The RBI (R bands by BrdU using immunological staining) and GBI (G bands by BrdU using immunological staining) band patterns were complementary for all chromosomes. There was no overlapping, and every part of each chromosome was positively stained by one of the two banding procedures. Comparative analysis of RBG (R bands by BrdU using Giemsa staining) and RBI band patterns, as well as GBG (G bands by BrdU using Giemsa staining) and GBI band patterns, showed good congruency, displaying a very good band-for-band match. The congruency and complementarity found for these band patterns show that high concentrations of both thymidine and BrdU blocked S-phase progression near the R-band to G-band replication transition within the S phase. They also prove that BrdU incorporation is complementary and, therefore, demonstrate the existence of the R/G transition: a possible regulatory checkpoint within the S phase of the cell cycle.     

Choroidal melanoma in an African-American albino

PURPOSE: To report the rare occurrence of choroidal melanoma in an African-American albino. METHODS: A 68-year-old African-American man with oculocutaneous albinism developed an amelanotic choroidal mass in his left eye. A transvitreal fine-needle aspiration biopsy was performed to confirm the diagnosis, and the patient was treated with iodine 125 plaque radiotherapy. RESULTS: The cytology of the needle biopsy showed spindle cells with nuclear atypia and prominent nucleoli. The cells showed positive immunoreactivity for HMB-45, supporting the diagnosis of choroidal melanoma. CONCLUSION: To our knowledge, this is the first reported case of a choroidal melanoma occurring in an African-American albino.     

Isolation and characterization of glycogen synthase in Dictyostelium discoideum

We have partially purified the protein and isolated the glcS gene for glycogen synthase in Dictyostelium. glcS mRNA is present throughout development and is the product of a single gene coding for 775 amino acids, with a predicted molecular mass of 87 kD. The sequence is highly similar to glycogen synthase from human muscle, yeast, and rat liver, diverging significantly only at the amino and carboxy termini. Phosphorylation and UDPG binding sites are conserved, with K(m) values for UDPG being comparable to those determined for other organisms, but in vitro phosphorylation failing to convert between the G6P-dependent (D) and -independent (I) forms. Enzyme activity is relatively constant throughout the life cycle: the I form of the enzyme isolates with the soluble fraction in amoebae, switches to the D form, becomes pellet-associated during early development, and finally reverts during late development to the I form, which again localizes to the soluble fraction. Deletion analysis of the promoter reveals a GC-rich element which, when deleted, abolishes expression of glcS.