Electrocatalytic reduction of hydrogen peroxide at a stationary pyrolytic graphite electrode surface in the presence of cytochrome c peroxidase: a description based on a microelectrode array model for adsorbed enzyme molecules

Electrochemical reduction of H2O2 at pyrolytic graphite disc electrodes of radius 2.5 mm occurs at readily accessible potentials (600 mV versus the standard hydrogen electrode) in the presence of yeast cytochrome c peroxidase. Introduction of the enzyme into the electrolyte solution initiates large changes in the ellipsometric angles measured for the electrode-solution interface, consistent with time-dependent enzyme adsorption. This process may be correlated with changes in electrochemical activity. Over the same time course, linear-sweep voltammograms are characterized by a transition from a sigmoidal to a peak-type waveform. It is proposed that the time-dependent behaviour may be rationalized by use of a microscopic model for substrate mass transport, in which the two-electron reduction of peroxide occurs at electrocatalytic sites consisting of adsorbed enzyme molecules. A voltammetric theory based on treating the adsorbed redox enzymes as an expanding array of microelectrodes is in excellent agreement with experiment.     

Muon-spin-relaxation studies on the heavy-fermion system with non-Fermi-liquid behavior CeCu5.9Au0.1

A patient with a history of pelvic radiation therapy for seminoma presented with a prostatic tumor, which appeared predominantly of high signal intensity on T2-weighted magnetic resonance images; low-signal-intensity tissue also extended to the pelvic sidewall. At surgical pathology, the tumor was determined to be radiation-induced sarcoma of the prostate, and the extraprostatic tissue was postradiation fibrosis.     

Synthesis and antiplatelet effects of omega-aminoalkoxylxanthones

A series of omega-aminoalkoxylxanthones were synthesized and tested in-vitro for their ability to inhibit aggregation of rabbit washed platelets and human platelet-rich plasma (PRP) induced by various inducers. Nine of these compounds showed more potent antiplatelet effects than natural norathyriol tetraacetate on collagen-induced aggregation. The various omega-aminoalkoxyl side chains of the synthesized compounds modified the antiplatelet effects. All the compounds tested in human PRP showed significant inhibition of secondary aggregation induced by adrenaline, suggesting that the antiplatelet effects of these compounds is mainly due to an inhibitory effect on thromboxane formation. These compounds at high concentration also cause vasorelaxing action in rat thoracic aorta.     

Cephalic tetanus: demonstration of a dual lesion

A clinical and electrophysiological study of 15 cases of cephalic tetanus is reported. This condition is a form of local tetanus which commonly follows an injury to the face or head. It is characterised by muscle paralysis which is maximal close to the site of injury, while spasm is evident at mroe distant sites. As muscle paralysis improves with time it is succeeded by spasm. It is argued that paralysis is due to high local concentrations of toxin in the brainstem while lesser concentrations cause spasm by abolishing inhibition. Electrophysiological studies indicate that paralysis is of lower motor neurone type with denervation potentials, hyperirritability, loss of motor units, and marginally increased distal latencies being the features recorded.     

CD4+ T lymphocytes contribute to protective immunity induced in sheep and goats by Haemonchus contortus gut antigens

"Freezing" is a sudden, unforeseen state of immobility occurring independently of L-Dopa dosage timing and often presents in connection with walking, speech and hand movements. The immobility results from deficits in initiating or simultaneously and sequentially executing movements, in correcting inappropriate movements or planning movements. However, since the progression of motor activity is strongly dependent upon external stimuli, the patient can overcome the freezing phenomena with the aid of certain stimuli or subjective strategies. No consistent relationships have been found with respect to age, length of illness, L-dopa dosis or L-dopa treatment. Neurotransmitter models to explain the freezing phenomena are: a noradrenalin deficiency in locus coeruleus or alternately a dopamine deficiency in substantia nigra, pars compacta, which can possibly be coupled with a GABA deficiency in substantia nigra, pars reticulata. In addition to optimal drug therapy, patients require physiotherapeutical and ergotherapeutical assistance to develop subjectively effective strategies in counteracting freezing during everyday activities.     

Hyperhomocysteinemia increases intimal hyperplasia in a rat carotid endarterectomy model

PURPOSE: This preliminary study investigated the ability to elevate the serum homocysteine (H[e]) levels and investigated the increases in postoperative neointimal hyperplasia (IH) in an environment with hyperhomocysteinemia and the resultant restenosis in a rat carotid endarterectomy (CEA) model. METHOD: The 9 rats for the control group were fed rat chow, and the 8 rats for the H(e) group were fed H(e)-supplemented rat chow for 2 weeks before and after CEA. The animals underwent anesthesia, and a left common CEA was performed. After 14 days, the serum H(e) levels were measured and the left carotid artery was harvested and elastin stained. Morphometric measurements were used to calculate the area of stenosis of the lumen. The mean and the standard deviation of the mean were determined. The 2 groups were compared with the Mann-Whitney test and a linear regression model. Three additional rats per group were studied, with carotid artery sectioning with double immunohistochemical staining for 5-bromodeoxyuridine (BrdU) and alpha-smooth muscle (alpha-SM) actin. RESULTS: The serum H(e) level in the H(e) group was 36.32 micromol/L +/- 15.28, and in the control group the level was 5.53 micromol/L +/- 2.06 (P =.0007). IH presented as percent lumen stenosis was 21.89% +/- 4.82% in the H(e) group and 4.82% +/- 1.64% in the control group (P =.0007). The linear regression model of the serum H(e) levels and the percent stenosis showed a linear relationship (r2 =.72). The alpha-SM actin staining revealed that nearly all of the cells in the IH area were of smooth muscle or myofibroblast origin and that 10.1% +/- 2.6% of the cells were stained for BrdU in the control group versus 23% +/- 7.1% in the H(e) group. Also, 9.3% +/- 2.6% of the cells in the IH area were stained for BrdU and for alpha-SM actin versus 19.1% +/- 5. 6% stained for both BrdU and alpha-SM actin in the H(e) group. CONCLUSION: This is the first study to examine IH after CEA and hyperhomocysteinemia in rats. The study shows that the elevation of serum H(e) levels can be obtained by feeding rats modified diets with added H(e). The consistent elevation of serum H(e) levels was associated with more than 4 times the amount of IH after a CEA in a rat model.     

The influence of traditional religion on fertility regulation among the Kassena-Nankana of northern Ghana

This article presents findings from a study of the influence of traditional religion on reproductive preferences of Kassena-Nankana lineage heads in northern Ghana. Seven reproductive preference questions were administered to nine lineage heads who are primary practitioners of the cult of soothsaying. With the assistance of soothsayers, interviews were repeated in conjunction with the invocation of religious rites in order to determine the views of ancestral spirits on the seven questions. Pairs of lineage head and ancestral interviews are compared to determine the role of traditional religion in shaping male reproductive preferences. Interview pairs reflect a shared preference for sons, large compounds, and a growing lineage. Findings nonetheless show that some ancestral spirits want small families, some even wanting fewer children than corresponding lineage heads. Spiritual consultations are nondogmatic and open to external ideas and influences, suggesting that family planning introduction will not encounter systematic religious opposition among the Kassena-Nankana.