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Biomedical subjects

A Hobbs

Publications and source records attributed to A Hobbs.

11 recordsLinked to original sources
PubMed2000

Synthesis and biological evaluation of enantiopure thionitrites: the solid-phase synthesis and nitrosation of D-glutathione as a molecular probe.

The D-isomer of the naturally-occurring tripeptide glutathione (gamma-L-Glu-L-Cys-Gly, L-GSH) has been synthesised using the Fmoc solid phase peptide synthesis strategy. The D-GSH obtained has been nitrosated to give the D-isomer of the bioactive thionitrite, S-nitroso-L-glutathione. The biological activity of both enantiomers of S-nitrosoglutathione has been studied and compared to the activity of the D- and L-isomers of N-acetyl-S-nitrosopenicillamine (SNAP) and S-nitrosocysteine (CysNO).

Animals↗
PubMed2000

Gastrointestinal motility during pregnancy: role of nitrergic component of NANC nerves.

This study evaluated whether increased release of nitric oxide (NO) from the nitrergic component of the nonadrenergic, noncholinergic (NANC) nerves may be partly responsible for the decrease in gastrointestinal motility observed during pregnancy. Segments of fundal strip, ileum, and colon were obtained from nonpregnant rats, rats in midpregnancy (days 9-11), and rats in late pregnancy (days 18-20). NANC activity was studied by assessing changes in tone after application of electric field stimulation (EFS). The role of NO was determined by observing the effects of EFS in the presence and absence of the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) and the reversibility of the effects of L-NAME by L-arginine. The magnitude of change in cGMP levels in the tissues after application of EFS was also assessed. Our studies indicate that there was increased magnitude of relaxation of isolated strips of rat gastric fundus and rat colon, after application of EFS to tissues obtained only from animals in late pregnancy. These results paralleled the changes in cGMP levels in tissues. NOS activity in the gastric fundus was significantly increased in animals in late pregnancy compared with nonpregnant controls. Our studies suggest that the delay in gastric emptying and increase in colonic transit time observed in rats during pregnancy may be caused in part by increased activity of the nitrergic component of the NANC nerves innervating these organs.

Acetylcholine↗
PubMed1999

Sequence analysis and expression of a mRNA for a larval-specific cuticular protein, LCP1, from Helicoverpa armigera.

Several cDNA clones for a larval cuticular protein from Helicoverpa armigera were isolated and sequenced. The cDNA clones contain an open reading frame encoding a 109 residue protein which is homologous to other known cuticular proteins. The predicted protein appears to have a signal peptide which would be removed to give a mature protein of 91 amino acid residues with an Mr of 10 127. The mature protein, LCP1 (Larval Cuticular Protein), would be highly acidic, as is found for other cuticular proteins from flexible insect cuticles. The mRNA appears to be expressed throughout larval development although it is more highly expressed in the integument of the late final instar.

Amino Acid Sequence↗
PubMed1999

Mapping variation in brain structure and function: implications for rehabilitation.

The recognition of structural and functional variability of the human brain promoted the development of a system to organize and analyze the rapidly growing body of knowledge acquired among diverse disciplines. The Human Brain Project (HBP) was initiated and has evolved as a means of establishing an information infrastructure through tools related to the emerging science of neuroinformatics. This article will briefly describe the implications that such an endeavor has for the field of traumatic brain injury (TBI) rehabilitation.

Brain↗
PubMed1993

Pre-steady-state charge translocation in NaK-ATPase from eel electric organ.

Time-resolved measurements of charge translocation and phosphorylation kinetics during the pre-steady state of the NaK-ATPase reaction cycle are presented. NaK-ATPase-containing microsomes prepared from the electric organ of Electrophorus electricus were adsorbed to planar lipid bilayers for investigation of charge translocation, while rapid acid quenching was used to study the concomitant enzymatic partial reactions involved in phosphoenzyme formation. To facilitate comparison of these data, conditions were standardized with respect to pH (6.2), ionic composition, and temperature (24 degrees C). The different phases of the current generated by the enzyme are analyzed under various conditions and compared with the kinetics of phosphoenzyme formation. The slowest time constant (tau 3(-1) approximately 8 s-1) is related to the influence of the capacitive coupling of the adsorbed membrane fragments on the electrical signal. The relaxation time associated with the decaying phase of the electrical signal (tau 2(-1) = 10-70 s-1) depends on ATP and caged ATP concentration. It is assigned to the ATP and caged ATP binding and exchange reaction. A kinetic model is proposed that explains the behavior of the relaxation time at different ATP and caged ATP concentrations. Control measurements with the rapid mixing technique confirm this assignment. The rising phase of the electrical signal was analyzed with a kinetic model based on a condensed Albers-Post cycle. Together with kinetic information obtained from rapid mixing studies, the analysis suggests that electroneutral ATP release, ATP and caged ATP binding, and exchange and phosphorylation are followed by a fast electrogenic E1P-->E2P transition. At 24 degrees C and pH 6.2, the rate constant for the E1P-->E2P transition in NaK-ATPase from eel electric organ is > or = 1,000 s-1.

Animals↗
PubMed1985

The effects of methyl beta-carboline-3-carboxylate on social interaction and locomotor activity when microinjected into the nucleus raphé dorsalis of the rat.

Intraperitoneal and intracerebral injections of methyl beta-carboline-3-carboxylate (beta CCM) and intracerebral injections of RO 15-1788 were given to rats. The performance of the rats in the social interaction test was measured to determine if changes in social interaction induced by beta CCM were mediated in part by the nucleus raphé dorsalis (NRD). Intraperitoneal injections of beta CCM, 2 and 4 mg kg-1, reduced social interaction. Intracerebral microinjections of beta CCM (10-0.1 ng in 0.5 microliter) into the NRD reduced social interaction. Injections outside the NRD did not have this effect. Intracerebral microinjections of RO 15-1788 (1 ng in 0.5 microliters) into the NRD had no effect when given alone, but blocked the reduction in social interaction caused by intracerebral or intraperitoneal injections of beta CCM. No effect was observed when R 15-1788 was microinjected into sites outside the NRD. Changes in social interaction may reflect changes in anxiety. The NRD may be one of the important sites for the expression of the anxiogenic actions of beta CCM.

Animals↗
PubMed1982

Relationship between natural killer cell activity and histological features of lymphocyte infiltration and partial regression of the primary tumor in melanoma patients.

A group of 194 melanoma patients with Stage I melanoma was studied in an attempt to correlate histological features of prognostic importance in malignant melanoma with the level of natural killer cell (NK) activity in blood mononuclear cells. Histological features examined were lymphocytic infiltrate of the tumor base, lymphocyte infiltration at the tumor margin, and evidence of partial regression in the tumor. NK activity against melanoma cells and non-melanoma cells was studied in the same patients before and after surgical removal of melanoma. Patients with high NK activity against melanoma and Chang cells had less lymphocyte infiltrate at the base of the tumor irrespective of its thickness than did those with low NK activity. Patients with low NK activity and thin tumors had more lymphocyte infiltration at the base of the tumor than did those with high NK activity. Similar results were obtained in certain subsets of cases with respect to lymphocytic infiltration at the tumor margins and to the presence of partial regression. Although the nature of the association between these histological features and NK activity in blood is unknown, it is suggested that previously unexplained associations between histological features and prognosis may be accounted for by their association with NK activity. If this proves to be correct, measurement of NK activity may be an important additional prognostic factor in patients with melanoma.

Cytotoxicity, Immunologic↗
PubMed1977

Two cases of trisomy 21 and one XXY case with atypical clinical features.

Three patients with mental retardation and multiple congenital abnormalities are described. Although their clinical appearance was not suggestive of Down's syndrome, chromosome studies showed a non-disjunctional trisomy 21 in two of the patients. The third case had an unsuspected XXY karyotype.

Abnormalities, Multiple↗
PubMed1974

Sydney Krantz.

Explore the source record for details and available documents.

Australia↗
PubMedDate not supplied

Availability of insulin from total parenteral nutrition solutions.

Insulin is frequently required in total parenteral nutrition (TPN) solutions to control hyperglycemia. The purpose of this study was to evaluate the recovery of human insulin from standard TPN solutions with and without lipids and from TPN solutions with specialized amino acid formulations and to compare it to the insulin recovery from normal saline. All solutions were mixed in currently utilized PVC-free bags (ethylene vinyl acetate) and drained through PVC-containing tubing. Human insulin (Humulin-R) was spiked with 125I-labeled insulin and then added in concentrations of 10, 25, and 50 units to 1-liter bags containing 39-g amino acids (10% Freamine-III; or 6.9% Freamine HBC; or 8% Hepatamine), 257-g dextrose, electrolytes (Hyperlyte-R), 1000 units of heparin, MVI-12, and MTE-5 Concentrate. Alternate sets of bags contained 125 ml of 20% Intralipid and an appropriate amount of sterile water to keep the final volume at 1 liter. Actual clinical conditions of preparation, storage, and administration were simulated in this in vitro experiment. Multiple samples were collected during the 8-hr infusion period directly in gamma counter vials. All experiments and assays were done in triplicate. Our findings indicate that human insulin availability in TPN solutions is much higher (90%-95%) than the 50% suggested in the literature. Insulin recovery was not appreciably altered by adding lipids or by using Freamine HBC. Insulin recovery from TPN solutions was significantly reduced if they contained Hepatamine (87% and 88%, p less than 0.05) as compared to Freamine (90% and 94%).(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗