Menarcheal age in University of Warwick young women

The influence of ischemia on purine nucleotide and their catabolite concentration in human myocardium was investigated during surgery of acquired and congenital heart defects. This was compared with the influence of ischemia on rat heart. Concentrations of adenine and guanine nucleotides and their catabolites were measured in the extracts of heart biopsies taken at the onset of ischemia and at the time of reperfusion. The content of myocardial ATP in human heart decreased from the initial value of 22.3 +/- 1.1 to 14.6 +/- 1.5 nmol/mg protein and total adenine nucleotide pool decreased from 34.2 +/- 1.8 to 27.6 +/- 1.5 nmol/mg protein during the operation. Significant increases in myocardial concentrations of purine catabolites were also observed with the most prominent rise in inosine from below 0.5 at the onset of the ischemia to 3.0 +/- 0.5 nmol/mg protein at the time of reperfusion. A positive correlation was demonstrated between the concentration of purine catabolites in the heart at the end of ischemia with the decrease of both ATP and the total nucleotide pool. An interesting metabolic specificity of the ischemic human heart appeared to be only a small accumulation of inosine monophosphate (IMP). The increase of IMP in the rat heart after ischemia was several-fold higher. Thus, cardiac surgery of congenital and acquired heart defects was associated with a significant decrease in myocardial adenylate pool and a single biopsy collected at the end of ischemia seems to be sufficient to evaluate the extent of this metabolic and possibly functional impairment of the heart.     

Classification of temporal patterns in dynamic biological networks

A general method is presented to classify temporal patterns generated by rhythmic biological networks when synaptic connections and cellular properties are known. The method is discrete in nature and relies on algebraic properties of state transitions and graph theory. Elements of the set of rhythms generated by a network are compared using a metric that quantifies the functional differences among them. The rhythms are then classified according to their location in a metric space. Examples are given, and biological implications are discussed.     

Post-translational cleavage of a histone H1-like protein in the sperm of Mytilus

Starting with total RNA from spermatogenic cells of Mytilus trossulus and using random priming, we have cloned and sequenced the c-DNAs corresponding to two variants of the sperm-specific protein PLII* (phi 2B). DNA sequencing in conjunction with mass spectrometry and protein sequence data have allowed us to establish that of the three sperm-specific proteins present in the sperm of Mytilus (PL-II*(phi 2B), PL-III (phi 1), PL-IV (phi 3)), the first and the last one are the result of post-translational cleavage of a common precursor. This common precursor is a member of the histone H1 family, and it exhibits inter- and intraspecific microheterogeneity.     

Spatial-Semantic Display Processing: The Role of Spatial Structure on Recall

The purpose of the present study was to test a model of spatial-semantic display processing by comparing the aided and unaided recall of information presented in a node-link format (knowledge map) to the aided and unaided recall of information presented in a text format. Structural icons of the knowledge map and text with the verbiage removed were used to aid retrieval in some conditions. Participants were randomly assigned to one of eight groups formed by the complete crossing of three factors: knowledge map versus text, structural icon at recall versus no structural icon at recall, and immediate versus delayed recall. Knowledge map groups outperformed text groups on essay tests and they more accurately remembered where information was located within the materials. Both knowledge map and text icon-aided recall groups had significantly better performance than the no icon, unaided recall groups (particularly on main ideas).     

The new partnership of genomics and chemistry for accelerated drug development

The Grashey shoulder position is used to demonstrate damage to the glenohumeral joint caused by osteoarthritis, sclerosis, tumors, fractures, osteophytes and cystic changes. However, it can be difficult to assess loss of articular cartilage using the Grashey shoulder position because little axial load is applied to the glenohumeral joint. This article describes a method of creating a loading force across the glenohumeral joint by adding weighted arm abduction during the Grashey position to demonstrate loss of the articular cartilage. Case studies and radiographs are presented to discuss the advantages of using the Grashey position with weighted abduction.     

Energy relaxation in GaInAs/AlInAs heterojunctions and GaAs/AlGaAs multiple quantum wells

We have studied electron energy relaxation in GaInAs/AlInAs heterojunctions and GaAs/AlGaAs multiple quantum wells using mobility measurements as a function of electric field and temperature, in the range 3K to 300K. The results in the range 3 to 20K show a power loss rate which is dependent on (T_e − T_l), suggesting that the energy relaxation occurs through acoustic phonon scattering. At electron temperatures greater than 20K, the experimental results are modelled using a standard expression for polar optical phonons. This modelling yields 30meV and 31meV for the polar optical phonon energy in GaAs and InGaAs respectively.     

Immunoglobulin A levels in southern elephant seal (Mirounga leonina) milk during the suckling period

Immunoglobulin A (IgA) levels in milk samples from southern elephant seals at King George Island, Antarctica are reported. IgA levels were determined throughout the suckling period (approximately 23 days). The IgA concentration in southern elephant seal milk was lower than in other mammals and, unlike most mammalian milk, was not high during early lactation. There was not a definite pattern in IgA levels, which fluctuated within narrow limits throughout the suckling period (mean +/- SD, 30.81 +/- 6.38 mg IgA/100 g milk). If IgG was present, its level was too low to be detected by the method used. This is the first evidence in Southern elephant seal of the possibility of transmission of passive immunity after birth involving secretion of IgA in the milk.     

The soluble alpha-mannosidases of Drosophila melanogaster

The alpha-mannosidases are implicated in both the catabolism of carbohydrates and the N-linked glycosylation pathway in insects, but little is known of the biochemistry of these glycosidases. In order to study the soluble alpha-mannosidases of Drosophila melanogaster we have used artificial fluorogenic substrates for detection of activity in situ following non-denaturing gel electrophoresis. This approach also permitted examination of the mannosidases present in different tissues and the sensitivity of the enzymes to known mannosidase inhibitors. Fluorogenic substrates were also used to determine the pH optima of partly purified mannosidases. We report that D. melanogaster contains several soluble alpha-mannosidase activities. Acidic mannosidases were detected in the gut, fat body and haemolymph of third-instar larvae. The major activity detected in larval guts was a neutral mannosidase presumed to be involved in digestion.     

Plasma membrane phospholipid fatty acid composition of cultured skin fibroblasts from schizophrenic patients: comparison with bipolar patients and normal subjects

Recent studies have found lower red cell plasma membrane contents and composition of the long chain polyunsaturated essential fatty acid derivatives, particularly arachidonic acid and docosahexaenoic acid, in a subgroup of chronic schizophrenic patients. These fatty acids are particularly enriched in the brain. Red blood cell levels of fatty acids are influenced by diet, medications, and other factors. Cell plasma membrane compositions of arachidonic and docosahexaenoic acids were therefore examined in cultured skin fibroblasts from 12 schizophrenic patients, 8 of whom were drug-naive and in a first episode of psychosis, 6 bipolar patients, and 8 normal control subjects. Docosahexaenoic acid as well as total n-3 essential fatty acid contents were significantly lower in cell lines from schizophrenic patients than in cell lines from bipolar patients and normal subjects, with no difference between the latter two groups. Arachidonic acid levels did not differ across the groups. The essential fatty acid profile observed is consistent with deficient delta-4 desaturase activity in schizophrenic patients.